TFTR produces >3MW controlled fusion power
Steve Fairfax
at the Princeton Plasma Physics Laboratory (PPPL) performed experiments
with deuterium-tritium mixtures that approached the "ideal" ratio of
50/50 D-T. Preliminary results indicate fusion power production in excess
of 3 MW, a new world record. The experiments will continue. Several news
reports of the experiments have been published, and more are expected.
I congratulate the TFTR team on this accomplishment and look forward to more
exciting results in the future.
P.S. I had hoped that a PPPL person would post the results, as they would be
in a much better position to answer questions on the details of the
experiments. Mr. Heeter, where are you?
Robert F. Heeter
From: Steve Fairfax, Fai...@CMOD.PFC.MIT.EDU
Date: Fri, 10 Dec 1993 18:09:30 GMT
In article <Fairfax.2...@CMOD.PFC.MIT.EDU> Steve Fairfax,
I have been having trouble with network connectivity; I posted a
reply to this message several hours ago and haven't seen it show
up on any of the three domains I have access to. So I will
try again.
At any rate, I can add that new shots this afternoon have (almost)
redoubled that power record! They announced 5.5 megawatts over
the PA system at the lab this afternoon.
This is really a wonderful time, everyone is pretty excited here.
Even us lowly first-year graduate students with no particular
connection to TFTR (save that we work at the lab, and like fusion)
are glowing a little. (Psychologically, not radioactively!)
This event should make it into the mainstrem national media over
the next few days, and hopefully others more qualified than I
will join the discussion here and add some commentary.
For the skeptics out there, I will add that the 5.5 MW of power
generated must be compared to the 25-30 MW of power poured into
the plasma, so the efficiency is still short of breakeven.
But it's a lot closer than it was before, and it's good to know
that the plasma hasn't chosen to do anything exceptionally
pathological (as it seems to enjoy doing). I believe the TFTR
people expect to break 10 MW sometime during the DT phase,
which will continue until (roughly) next September or so...
While I can't profess to be an expert on TFTR, I'd be happy to
try answering any questions people may have...
**********************************************
Robert F. Heeter
Graduate Student, Princeton Plasma Physics Lab (PPPL)
Disclaimers certainly apply.
rfhe...@phoenix.princeton.edu
Allen Robinson
: Last night, at approximately 11 PM, the Tokamak Fusion Test Reactor (TFTR)
I first heard of this event on NPR's morning edition this a.m.
I tried to watch CNN throughout the day for further info. Then
finally caught a brief segment on one of the network evening
newscasts. It seems everyone was giving a different time for the
duration of the event. If I remember correctly, NPR said something
like "about 7 seconds." CNN, I believe, was saying 5 seconds, and
I think I heard them say on the evening news only about a second.
What is correct?
Robert F. Heeter
From: Rob Jellinghaus, ro...@netcom.com
Date: Sat, 11 Dec 1993 02:01:36 GMT
In article <robjCHu...@netcom.com> Rob Jellinghaus, ro...@netcom.com
writes:
>For those of us who are unfamiliar with the context of the
>experiments, how significant is 3MW of heat production? How much
>energy was required to create the fusion reaction, and what are the
>implications of this success for large-scale fusion power?
>
>I also have seen none of the news reports, so please excuse my
>ignorance.
>
I hope other have answered this already, but if not, here's my
contribution.
In 1971, you really didn't generate any fusion power. In 1981,
you could get maybe 100-1000 watts. Now we have 5.5 megawatts
(In a run on Friday they boosted the power output from 3 to 5.5 MW).
This was done using roughly 30 megawatts of input power, so while
we're getting closer to a large-scale, economic fusion reactor,
we still have some distance to go.
The critical parameter for fusion, which is basically the
product (particle density * temperature * confinement time), has
increased by a factor of about 10,000 in the past 20 years. We
need (roughly) another factor of 10 improvement in order to start
building power stations. (Source - PPPL data; I'd be happy to
explain this further.)
The previous best result was 1.7 megawatts generated in JET (Joint
European Torus) in Britain in 1991. So 5.5 megawatts is another
big (though not particularly unexpected) advance. The real
significance of the results is that the plasma actually behaved
roughly as expected. Plasma tend to do unexpected things, and
you never really know what will happen until you do the experiment.
Successful generation of megawatt-size quantities of power is
an important milestone in the fusion research effort.
Hope this helps!
Bob Heeter
rfhe...@phoenix.princeton.edu
Graduate Student, Princeton Plasma Physics Lab
(The usual disclaimers apply.)
Rob Jellinghaus
experiments, how significant is 3MW of heat production? How much
energy was required to create the fusion reaction, and what are the
implications of this success for large-scale fusion power?
I also have seen none of the news reports, so please excuse my
ignorance.
--
Rob Jellinghaus ro...@netcom.com uunet!netcom!robj
Fritsch_Wolfgang
>The previous best result was 1.7 megawatts generated in JET (Joint
>European Torus) in Britain in 1991. So 5.5 megawatts is another
>big (though not particularly unexpected) advance. The real
>significance of the results is that the plasma actually behaved
>roughly as expected. Plasma tend to do unexpected things, and
>you never really know what will happen until you do the experiment.
>Successful generation of megawatt-size quantities of power is
>an important milestone in the fusion research effort.
I wonder what has been the key factor in getting the energy output.
Is it more than using the 'right' mixture of deuterium and tritium?
So is it more than the technological advance of handling tritium
savely in such device?
Wolfgang Fritsch
p...@psun2.hmi.de
Paul M. Koloc
>Subject: TFTR produces >3MW controlled fusion power
>From: Steve Fairfax, Fai...@CMOD.PFC.MIT.EDU
>Date: Fri, 10 Dec 1993 18:09:30 GMT
>In article <Fairfax.2...@CMOD.PFC.MIT.EDU> Steve Fairfax,
>Fai...@CMOD.PFC.MIT.EDU writes:
>At any rate, I can add that new shots this afternoon have (almost)
>redoubled that power record! They announced 5.5 megawatts over
>the PA system at the lab this afternoon.
>This is really a wonderful time, everyone is pretty excited here.
>Even us lowly first-year graduate students with no particular
>connection to TFTR (save that we work at the lab, and like fusion)
>are glowing a little. (Psychologically, not radioactively!)
I bet you can't say that about the limitors and wall.
>For the skeptics out there, I will add that the 5.5 MW of power
>generated must be compared to the 25-30 MW of power poured into
>the plasma, so the efficiency is still short of breakeven.
Ahhh! That's "Scientific Breakeven" and not Commercial where
about 2000 or more times current levels will be needed. Don't
you feel the opposite, that now that the TFTR has shot it's
wad -- so to speak--- you are hopelessly orders of magnitude
from commercial deliverence performances.
>But it's a lot closer than it was before, and it's good to know
>that the plasma hasn't chosen to do anything exceptionally
>pathological (as it seems to enjoy doing).
Gee, you used a radioactive highly diffusive gas, tritium,
for the first time in ideal amounts. And, hey, even a tad more
thermalization helps improve conductivity which is beneficial.
So what's the surprize????
>I believe the TFTR
>people expect to break 10 MW sometime during the DT phase,
>which will continue until (roughly) next September or so...
Ouch... That's a lot of hot neutrons and diffusioning tritium.
>While I can't profess to be an expert on TFTR, I'd be happy to
>try answering any questions people may have...
Surely, tell us about the rumors that a couple of other labs
are discussing alternate concepts at least on the QT, again?
Anything, buzzing of a similar ilk at pppl???
>**********************************************
>Robert F. Heeter
>Graduate Student, Princeton Plasma Physics Lab (PPPL)
>Disclaimers certainly apply.
>rfhe...@phoenix.princeton.edu
Sorry, hang in there and obtain your degree. Help is on the way.
+------------------------------------------------------------------------+
| Paul M. Koloc,Bx 222, Prometheus II, Ltd., College Park, MD 20740-0222 |
| mimsy!promethe!pmk; pmk%prome...@mimsy.umd.edu FAX (301) 434-6737 |
| VOICE (301) 445-1075 ***** Commercial FUSION in the Nineties ***** |
+------------------------------------------------------------------------+
Michael Condict
writes:
Why does everyone keep talking about the amount of energy output,
instead of the ratio of input energy to output energy. I see no
reason to get excited about the fact that you can input 30(?)MW and
get back 5.5, unless the ration 5.5/30 is a new record. (Is it?)
Otherwise, all people have to do to get in the news is keep building
bigger versions of reactors that are no closer to break-even than
previous ones -- they're just bigger, so the absolute output is higher.
Paul Koloc, please give us your assessment of this news.
--
Michael Condict con...@osf.org
OSF Research Inst. (617) 621-7349
1 Cambridge Center
Cambridge, MA 02142
julie england
great postings about what happened at PPPL last week, though he's
covered just about all of it! I got this information through email
from someone I know who works at PPPL (but not on TFTR). I don't
know any more than this.
Julie
>This is the first time that a major amount of tritium was used in TFTR.
>Trace tritium (a few percent) had been used earlier just to test the
>systems. (Two years ago there was a short tritium experiment on JET
>in England.) On Thursday evening, one beam source (out of about 10
>or 12) injected tritium into a deuterium fed plasma and a large
>increase in the neutron rate was observed. The calculated fusion power
>release was about 1 MW. On the next shot, 4 beam sources injected tritium
>and the neutron rate was larger. It was about a 3 MW fusion power release.
>That was all for that evening. The next day, the series was continued for
>about 5 more shots with more beam sources injecting into somewhat better
>plasmas due to careful wall conditioning. The fusion power release for
>the best shot was given at 5.6 MW average, but my friends tell me that
>the signal instantaneously reached 6 MW. The milestone for the experiment
>was 3 - 5 MW, so they made it.
--
*-------------------------------------**-------------------------------------*
| Julie England, Database Coordinator || Workshop in Political Theory and |
| eng...@silver.ucs.indiana.edu || Policy Analysis, Indiana University |
*-------------------------------------**-------------------------------------*
te...@asl.dl.nec.com
In article <Fairfax.2...@CMOD.PFC.MIT.EDU>
Fai...@CMOD.PFC.MIT.EDU (Steve Fairfax) writes:
Congratulations -- the results sound pretty good.
Can anyone (Mr. Heeter?) give a rundown on whether this experiment was
within the same range of results predicted based on pure D-D work? Were
there really any surprises in the energy production levels or containment
times, compared to D-D in the same system?
Cheers,
Terry
James A. Crotinger
> Gee, you used a radioactive highly diffusive gas, tritium,
> for the first time in ideal amounts. And, hey, even a tad more
> thermalization helps improve conductivity which is beneficial.
> So what's the surprize????
That the hot alpha particles didn't cause the plasma to do something
unexpected? Given that plasmas are largely goverened by Murphy's Law,
this is a breakthrough. 8-)
Jim
--
-------------------------------------------------/\--------------------------
James A. Crotinger Lawrence Livermore N'Lab // \ The above views are mine
j...@moonshine.llnl.gov P.O. Box 808; L-630 \\ //---\ and are not neces-
(510) 422-0259 Livermore CA 94550 \\/Amiga\ sarily those of LLNL.
John W. Cobb
>p...@prometheus.UUCP (Paul M. Koloc) writes:
>
James A. Crotinger <j...@moonshine.llnl.gov> wrote:
> That the hot alpha particles didn't cause the plasma to do something
>unexpected? Given that plasmas are largely goverened by Murphy's Law,
>this is a breakthrough. 8-)
>
> Jim
Jim has identified the crucial aspect of these experiments, for those
of you who have been posting asking "What's it all about"
It is not new that if you use a 50/50 D-T mix in a machine of the size
of TFTR you would get a lot of neutrons and a Q value of 0.1 with one order
of magnitude error bars. In fact these ideas were so well known that there
was almost no reason to do the experiment from a scientific point of view.
The almost is added because there is one issue that is very important
and cannot be resolved reliably just from theory and numerical simulation.
The hot alpha particle by products have an energy of about 4 MeV. They
will form a very hot component to the plasma. Ideally it will heat the
plasma by means of Coulomb collision and/or turbulent deceleration. However,
there is also the possibility that these hot alpha particles may excite
and unstable mode of oscillation that will degrade confinement. These are
sometimes called TAE modes or GAE modes, etc. The acronyms stand for
"Toroidal Alfven Eigenmodes" or "Global Alfven Eigenmodes". There are other
variants as well such as Ellipticity induced AE's, etc. My (limited)
understanding is that there is the possibility that the motion of hot alpha
particle is just fast enough to resonate with a very special set of Alfven
Waves in the plasma. This alpha motion is called "banana orbits".<see exp
below>
Usually exciting Alfven modes is not so bad because they are damped by
Landau damping and and by exciting other modes in a cascade. However, the
tokamak has toroidal symmetry, so it is periodic structure in the toroidal
angle. Therefore all of the potentials and fields look periodic, and
just like in condensed matter theory, discrete modes of oscillations
(electron orbitals) get lumped together into bands. For some frequencies
there is a continuous spectrum of modes and for others there are "gaps" or
frequencies were no modes propagate. Well it turns out that there are a
few single modes in the gap. That is a single, or just a few resonances.
This is the problem. The alpha particles may be able to excite these
modes. think of the modes like the guitar strings and the alpha particles
like the guitar pick. IF you keep strumming harder and harder, you will
break a string. Since it is a single resonance, you cannot mode convert
to other frequencies and reduce the energy to heat by phase mixing.
So this is the real interesting part for fusion physicists is will the
D-T experiments see these modes and will they prove to be an obstacle,
or will we be able to live with them (or maybe they don't even exist)
There has been a great deal of good theory and simulation about these modes
so it is not a shot in the dark. It is just that it is not an easy question
to settle. The fact that the initial reports showed neutron fluxes in the
right "ball park" is an indication that these modes may be absent, or if
they are present they are benign.
This is very noteworthy. The history of fusion energy development is that
at every turn there is another "monster guarding the door". Whether it is
MHD instabilities, drift or other micro-instabilities, or turbulent transport.
As each monster has been killed (or caged) and the door it was guarding
opened, another monster has reared its head. Well there is not room for
many more monsters to exist between where we are now and ignition. Of
course there are very significant engineering problems yet to be tackled,
but that's another issue. :>
While I'm spitting out gee-whiz numbers, let me just give one statement that
indicates how fast fusion has progressed. People often look to the
semi-conductor and computer industry as an industry that has made fast
(read breakneck) advances in their figures of merit (device size, speed,
total number of gates, etc). The figure is something like a doubling every
2 years. Well the search for fusion has progressed even faster. The rate of
maximum fusion triple product has been improving at an even faster rate,
eventhough funding support, in real dollars has been reduced 50%.
One of the last monsters is the possible problems with TAE's,GAE's, etc.
The fact that TFTR is not seeing them now is significant. Of course one
has to plug in the numbers. 5MW of neutron power implies about 1.25 MW
of alpha-heating. Thus only about 5% of the heating power in these shots
is provided by alphas. Whereas, at breakeven it will be about 25% and
at ignition it will be 100%. So even if there are no GAE's or TAE's now,
there is still room for them to be excited and destabilize the plasma.
Keep your fingers crossed while the D-T runs continue at Princeton over
the next year.
* What's a banana?
It describes the orbit of a charged particle in a particular set magnetic
field configurations. The tokamak has such a configuration. The lowest
order motion of a charged particle in a strong magnetic field is to move
in a helix centered on the magnetic field line. The particle circles the line
and can move along it. However, there is another effect. The particle's
motion will conserve a quantity called its "magnetic moment" which is the
ratio of the particles kinetic energy in motion perpendicular to the magnetic
field to the strength of the magnetic field. The magnetic moment is an
"adiabatic invariant" so although not strictly conserved, it is conserved to
a high degree. Now in a tokamak, the main field comes from the primary current
(or toroidal field coil) that runs through the center of the "doughnut". The
natural cylindrical geometry implies that the magnetic field is stronger
on the inner side of the torus than on the outer side. Note: inner side <>
inside. The inner side is the part of the doughnut that touches the
"doughnut hole" while the outer side is what hits the coffee first when you
dunk you doughnuts. These are sometimes called the "inboard" and "outboard"
sides.
In a tokamak, the magnetic fields are primarily toroidal in nature, but
they have a poloidal component as well. So if we follow a given magnetic
line it will in general go around the torus toroidally, but it will also
spiral toroidally. It looks a little like a "cruller" doughnut in this
respect. Now the particles follow these field lines. The general motion
is that they move along parallel (or anti-parallel) to the fields. However,
the particles must conserve their magnetic moment. So some particles cannot
make it to the inboard side of the torus. Instead they reach a point where
their entire energy is contained in perpendicular "gyrating" motion. At this
point their parallel velocity is reduced to zero and reverses. This is
called "mirroring" or a "mirror bounce". So now instead of following the
field line exactly, there are some particles that follow the line for a bit,
and then bounce and go back in the other direction.
There is one final correction. In fact all of the analysis is really
done as a perturbation expansion of the particle orbit using small
parameters. One of the parameters is the "gyro-radius" of the particles.
The gyro-radius is the radius of gyration of the particle around the
magnetic field line. It is sometimes called the Larmor radius or Lamour radius.
So in 0 gyro-radius approximations, the particles follow the lines
exactly (infinitely small gyration=no gyration) and if and when they bounce,
they just turn around on the same field line.
However, if one keeps the first order corrections in the orbits, you see the
gyrations. You will also see that the "guiding center" of that gyration, or
the instantaneous center of the circle of the particle's motion behaves
differently before and after the bound. When you look at the poloidal
projection of the orbit, it looks like a banana. It is this banana motion
of the alpha particles that can excite these TAE modes. Because the alphas
are so energetic, they have large banana widths and can therefore lead to
large excitations since many alphas have a bounce frequency that
resonates with the TAE mode. I would draw a picture, but I'm no good
at ascii graphics. You might look at Hazeltine and Meiss <Plasma Confinement>
(#86 in the Addison Wesley Frontiers in Physics series) on p. 141 for a
picture. or p. 194 of F. Chen's book <Intro. to Plasma Physics and Controlled
Fusion>.
-john .w cobb
John W. Cobb
In article <2ekjmp...@emx.cc.utexas.edu>,
John W. Cobb <john...@emx.cc.utexas.edu> wrote:
>In a tokamak, the magnetic fields are primarily toroidal in nature, but
>they have a poloidal component as well. So if we follow a given magnetic
>line it will in general go around the torus toroidally, but it will also
>spiral toroidally. It looks a little like a "cruller" doughnut in this
^^^^^^^^^^
poloidally ---- silly me
>respect. Now the particles follow these field lines. The general motion
>is
>-john .w cobb
>
>
Qian Qian
>>Why does everyone keep talking about the amount of energy output,
>>instead of the ratio of input energy to output energy. I see no
>>reason to get excited about the fact that you can input 30(?)MW and
>>get back 5.5, unless the ration 5.5/30 is a new record. (Is it?)
>
>>Otherwise, all people have to do to get in the news is keep building
>>bigger versions of reactors that are no closer to break-even than
>>previous ones -- they're just bigger, so the absolute output is higher.
>
>>Paul Koloc, please give us your assessment of this news.
>
>would think they got positive output!!! I thing that the real "Tokamak"
>reactor got up to 60% output > 30 years ago!!! I think a small reactor
>should be more unpredictable than a large reactor. So whats the big
>deal???? I smell a rat.
Yes,5.5out/30in is new record which was never been possibly
achieved without tritium. However, the significance of this event
is that TFTR's D-T results proved that
the fusion product(alpha particles) with high energy
didn't ruin the performance of the reactor itself(confinement
time) up to this stage, which was a big concern among fusion
scientists. Of course, it is still too early to say that tokamak
will have same confinement time when the output energy is
close to or even larger than the input as required by a
commercial reactor. further experiments on TFTR with D-T next
year with 10MW/30MW will give some clues.
Qian
--
-------------------------------------------------------------------------------
Real physics is originated from simplest systems! | PPL, P.O.Box 451
---Qian Qian | Princeton, NJ 08540
-------------------------------------------------------------------------------
Paul M. Koloc
>p...@prometheus.UUCP (Paul M. Koloc) writes:
>> So what's the surprize????
> That the hot alpha particles didn't cause the plasma to do something
>unexpected? Given that plasmas are largely goverened by Murphy's Law,
>this is a breakthrough. 8-)
If PPPL has reached the bottom of the barrel, I suppose it is. But what
happens come September 1994. That's when LLNL reaches into it's bag of
neato tricks to save the day??
>--
> Jim
>-------------------------------------------------/\--------------------------
>James A. Crotinger Lawrence Livermore N'Lab // \ The above views are mine
>j...@moonshine.llnl.gov P.O. Box 808; L-630 \\ //---\ and are not neces-
>(510) 422-0259 Livermore CA 94550 \\/Amiga\ sarily those of LLNL.
SEPTEMBER 1994
That big sucking sound
as TFTR vacuum is bled
for the last time
Paul M. Koloc
>In article <jac.755822495@gandalf>,
>>p...@prometheus.UUCP (Paul M. Koloc) writes:
>>> <(perhaps accurate) diatribe against tokamak fusion concepts>
The gentle man avoids the really killer (lethal) problems which relate
to lack of pressure transmission to the plasma resulting in pitifully
poor density, temperature, and confinement time. We are missing the mark
by orders of magnitude. Another huge lethal problem for tokamaks
and other wall solid vacuum wall confined systems is the plasma impurity
problem.
This one will guarantee that tokamaks can't SUSTAIN commercial
conditions EVEN IF they could by some magic obtain them initially.
>Jim ($ A. Crotinger) has identified the crucial aspect ..
> .. .. SEE POSTER "What's it all about"
>It is not new that if you use a 50/50 D-T mix in a machine of the size
>of TFTR you would get a lot of neutrons and a Q value of 0.1 with one order
>of magnitude error bars. .. .
Give me a break after how many decades of tokamak diagnostic research???
>The almost is added because there is one issue that is very important
>and cannot be resolved reliably just from theory and numerical simulation.
>The hot alpha particle by products have an energy of about 4 MeV. They
>will form a very hot component to the plasma. Ideally it will heat the
>plasma by means of Coulomb collision and/or turbulent deceleration. However,
>there is also the possibility that these hot alpha particles may excite
>and unstable mode of oscillation that will degrade confinement. These are
>sometimes called TAE modes or GAE modes, etc. The acronyms stand for
>"Toroidal Alfven Eigenmodes" or "Global Alfven Eigenmodes".
That's about as likely as the moon falling into lake Michigan at dawn
tomorrow.
The tokamak can be operated in the H or perhaps the Super H mode, One
of the things that happens is that fusion generally takes place in the
hotter portions of the plasma which are along or just peripheral to the
minor axis. Since Tokamaks are tokamaks and not Spheromaks the toroidal
field is not generated by plasma currents, consequently it tends to be
fixed. However, the toroidal plasma current tends toward tracking the
resultant mag field which is a mixture of toroidal field and itown
generated poloidal field. This field has helicity so the purely toroidally
driven plasma current (initially), starts to stretch its flow along
the helical mag flux lines. The poloidal current increases (and the
lessened toroidal component) diminishes the magnetic helicity and the
very much stronger rigid toroidal field snaps the plasma current back
to be more toriodal in nature. Thus there is an increase in toroidal
field and the whole process cycles. Since the tor-component of current
looks a bit like a "saw tooth", because of the jerking back and forth
in vector space, the phenomenon is named "saw tooth" action or some
such nomenclature.
Anyway the really important result of this is that it blows away the
99% of the theorized hot alpha induced and other disruptive effects.
This is done because the current jerking actually jerks plasma and
sloshes it in a vortex much like the clothes in a washing machine
are sloshed back and forth but more importantly are swirled in a
waltzing toroidal vortex about the spindle. For the wash every thing
gets blasted with soap and water, not just bubbles and air, and for
the plasma the hotter more ohmically heated minor axis is diffused
(actually mixed) with the adjacent plasma and over a substantial
cross-section. That reduces the thermal gradients (especially the
thermal electron gradient) and chops into bananas and other fruits
theorist may harass themselves with.
In the end, the theorist and more importantly, the bureaucrats
that rely on them will not have the nerve to go all the way with this
next machine and they will fail (like the Mirror machine). Of course,
they will endeavor to build a grand tokamak somewhere (perhaps the
south pole to take advantage of the remoteness, coolness, the natural,
vertical mag field and cheap Internationally flavored real estate.
HOWEVER they will never operate it. And this time they will not have
to use moth balls to store it!!!
> .. . There are other
>variants as well such as Ellipticity induced AE's, etc. My (limited)
>understanding is that there is the possibility that the motion of hot alpha
>particle is just fast enough to resonate with a very special set of Alfven
>Waves in the plasma. This alpha motion is called "banana orbits".<see exp
>below>
>Usually exciting Alfven modes is not so bad because they are damped by
>Landau damping and and by exciting other modes in a cascade. However, the
>tokamak has toroidal symmetry, so it is periodic structure in the toroidal
>angle. Therefore all of the potentials and fields look periodic, and
>just like in condensed matter theory, discrete modes of oscillations
>(electron orbitals) get lumped together into bands. For some frequencies
>there is a continuous spectrum of modes and for others there are "gaps" or
>frequencies were no modes propagate. Well it turns out that there are a
>few single modes in the gap. That is a single, or just a few resonances.
>This is the problem. The alpha particles may be able to excite these
>modes. think of the modes like the guitar strings and the alpha particles
>like the guitar pick. IF you keep strumming harder and harder, you will
>break a string. Since it is a single resonance, you cannot mode convert
>to other frequencies and reduce the energy to heat by phase mixing.
Sure and the the discrete number mag field coils can't be
eliminated since a "an open window" for fusion energy takeoff
is necessary. Of course, this is only because of the hidden
handicapped exceptionally unimaginative endeavor clause in all
of their DoE employment contracts. I. E. not one single National
Lab has ever been able to drop a loser concept and embrace a
more clever one, of itsown volition. In fact the National Labs
of the United States obtain thier fusion ideas mostly from
Russians.
>So this is the real interesting part for fusion physicists is will the
>D-T experiments see these modes and will they prove to be an obstacle,
>or will we be able to live with them (or maybe they don't even exist)
>There has been a great deal of good theory and simulation about these modes
>so it is not a shot in the dark. It is just that it is not an easy question
>to settle. The fact that the initial reports showed neutron fluxes in the
>right "ball park" is an indication that these modes may be absent, or if
>they are present they are benign.
If you believe this, then you don't believe this project was
set up to do this burn in 1983, and the DoE and PPPL conspired to
drag it out until congress basically forced the DT burn to be done.
The reason for the delay is: Who wants to kill off the goose (by
induced radioactivity) that lays the golden eggs.
>This is very noteworthy. The history of fusion energy development is that
>at every turn there is another "monster guarding the door". Whether it is
>MHD instabilities, drift or other micro-instabilities, or turbulent transport.
>As each monster has been killed (or caged) and the door it was guarding
>opened, another monster has reared its head. Well there is not room for
>many more monsters to exist between where we are now and ignition. Of
>course there are very significant engineering problems yet to be tackled,
>but that's another issue. :>
And all of these monsters were but the fantasy imagination of the
childishly developed science of plasma physics.
>While I'm spitting out gee-whiz numbers, let me just give one statement that
>indicates how fast fusion has progressed. People often look to the
>semi-conductor and computer industry as an industry that has made fast
>(read breakneck) advances in their figures of merit (device size, speed,
>total number of gates, etc). The figure is something like a doubling every
>2 years. Well the search for fusion has progressed even faster. The rate of
>maximum fusion triple product has been improving at an even faster rate,
>eventhough funding support, in real dollars has been reduced 50%.
Who fed you this one?? ??? ??
Oh Big Pain.... this is a whopper. You don't suppose the
absolute lack of all but miniscule progress in numbers had to
do with the fact that the tokamak is such a lemon it must come
in much more costly research devices in order to make the most
miniscule progress. And as soon as DT is burned in its 50-50
ratio very many times renders a tokamak machine essentially
useless. So it becomes toast. Of course if we shoot corks out
of straw cannons they will have more punch then a few sheets of
paper.
That's the analogy here. Using DT is like putting in a cork. The
problems is after a few shots the cannon's straw gives way, while
the tokamak becomes unapproachable for any serious research work.
So the GREAT PROGRESS in numbers is the result from the pitiful
fact that JET initially jumped the gun with partial tritium
mixtures and that PPPL was forced (finally) to use the ideal but
radioactive mixture for a burning tokamak, It's the dirtiest fuel
around and it's a must for the straw cannon ( tokamak).
So If the DoE wants to get serious than they should build their
house from mature plasma physics and engineering and not use straw,
Only a sustained PLASMA pressures in excess of 100 kilo bars can
do the trick. Sorry ICF the pressures must be SUSTAINED. Well
-- a SLOWWW compression on an internal magnetic ICF hybrid could
be viable.
>One of the last monsters is the possible problems with TAE's,GAE's, etc.
>The fact that TFTR is not seeing them now is significant. Of course one
>has to plug in the numbers. 5MW of neutron power implies about 1.25 MW
>of alpha-heating. Thus only about 5% of the heating power in these shots
>is provided by alphas. Whereas, at breakeven it will be about 25% and
>at ignition it will be 100%. So even if there are no GAE's or TAE's now,
>there is still room for them to be excited and destabilize the plasma.
>Keep your fingers crossed while the D-T runs continue at Princeton over
>the next year.
The monster(s) is(are) a fantasy... wishful thinking of a crowd
of chicken little's ?? making points to establish their
irreplaceable talent. With the really fundamental problems with
the engineering, This is sort of like worrying about teats on a bull.
They DO have them, Trust me I was a farm boy from Iowa, I'ts just
that they don't produce much milk, even with the miracle
milk_production_increase additives.
>* What's a banana?
It's a place to obtain a hair cut in College park.
In plasma physics, it's a curable disease. Simply apply
magnetoplasma shear to your fusion configuration (transmute it).
Spheromaks and PLASMAK(tm) are immunized against such blight (even
though it's probably not lethal) in practice in a burning, sawing,
tokamak). .
>It describes the orbit of a charged particle in a particular set magnetic
>field configurations. The tokamak has such a configuration. The lowest
>order motion of a charged particle in a strong magnetic field is to move
>in a helix centered on the magnetic field line. The particle circles the line
>and can move along it. However, there is another effect. The particle's
>motion will conserve a quantity called its "magnetic moment" which is the
>ratio of the particles kinetic energy in motion perpendicular to the magnetic
>field to the strength of the magnetic field. The magnetic moment is an
>"adiabatic invariant" so although not strictly conserved, it is conserved to
>a high degree. Now in a tokamak, the main field comes from the primary current
>(or toroidal field coil) that runs through the center of the "doughnut". The
>natural cylindrical geometry implies that the magnetic field is stronger
>on the inner side of the torus than on the outer side. Note: inner side <>
>inside. The inner side is the part of the doughnut that touches the
>"doughnut hole" while the outer side is what hits the coffee first when you
>dunk you doughnuts. These are sometimes called the "inboard" and "outboard"
>sides.
Yep, a holdover from the Stellarator days --- a big want of helicity.
>In a tokamak, the magnetic fields are primarily toroidal in nature, but
>they have a poloidal component as well. So if we follow a given magnetic
>line it will in general go around the torus toroidally, but it will also
>spiral toroidally. It looks a little like a "cruller" doughnut in this
>respect. Now the particles follow these field lines. The general motion
>is that they move along parallel (or anti-parallel) to the fields. However,
>the particles must conserve their magnetic moment. So some particles cannot
>make it to the inboard side of the torus. Instead they reach a point where
>their entire energy is contained in perpendicular "gyrating" motion. At this
>point their parallel velocity is reduced to zero and reverses. This is
>called "mirroring" or a "mirror bounce". So now instead of following the
>field line exactly, there are some particles that follow the line for a bit,
>and then bounce and go back in the other direction.
Well there you go, forcing a solution. Try "force free" currents
-- PLASMAK(tm) magnetoplasmoids (PMKs) . And,make them omnigenous
while you are at it. That's an automatic feature of isobarically
confined PMKs.
>There is one final correction. In fact all of the analysis is really
>done as a perturbation expansion of the particle orbit using small
>parameters. One of the parameters is the "gyro-radius" of the particles.
>The gyro-radius is the radius of gyration of the particle around the
>magnetic field line. It is sometimes called the Larmor radius or Lamour radius.
>So in 0 gyro-radius approximations, the particles follow the lines
>exactly (infinitely small gyration=no gyration) and if and when they bounce,
>they just turn around on the same field line.
>However, if one keeps the first order corrections in the orbits, you see the
>gyrations. You will also see that the "guiding center" of that gyration, or
>the instantaneous center of the circle of the particle's motion behaves
>differently before and after the bound. When you look at the poloidal
>projection of the orbit, it looks like a banana. It is this banana motion
>of the alpha particles that can excite these TAE modes. Because the alphas
>are so energetic, they have large banana widths and can therefore lead to
>large excitations since many alphas have a bounce frequency that
>resonates with the TAE mode. I would draw a picture, but I'm no good
>at ascii graphics. You might look at Hazeltine and Meiss <Plasma Confinement>
>(#86 in the Addison Wesley Frontiers in Physics series) on p. 141 for a
>picture. or p. 194 of F. Chen's book <Intro. to Plasma Physics and Controlled
>Fusion>.
Basically, the history of plasma physics can be judged by a
series of instability hysteria and other phases which can be
extracted by simply counting the kind and number of plasma
physics papers presented at the annual APS Plasma Physics Sessions.
Now, depending what "plasma epoch" one obtained a doctorate, we can
find a basis for communicating with that person. Sounds like an
interesting education or psych of science study.
You would be surprised at the effort that went into the nurture,
feeding and breeding of instabilities. This was followed by the
stuffing of The Current Hit Parade into the cranium of innocents.
(Krall and Trivelpiece) Sorry Nick. :-(
For the more northerly types, to see a banana "tip", you might
look up to the north some moonless winter night and see if you
can detect an aurora. Solar particles trapped in the earth's
field are in a sort of banana trap; and if they are too numberous
their pressure expandes or splits the trapping flux surfaces. As
the splitting continues further, they then can strike into,
igniting beautiful ionized sheets within the arctic exosphere.
>-john .w cobb
Good luck with your personal funding levels, John...
I'll be listening
for that final
PPPL tokamak
sucking sound.
John W. Cobb
Paul M. Koloc <p...@promethe.UUCP> wrote:
>In article <2ekjmp...@emx.cc.utexas.edu> john...@emx.cc.utexas.edu (John W. Cobb) writes:
>>>p...@prometheus.UUCP (Paul M. Koloc) writes:
>>>> <(perhaps accurate) diatribe against tokamak fusion concepts>
>
>to lack of pressure transmission to the plasma resulting in pitifully
>poor density, temperature, and confinement time. We are missing the mark
>by orders of magnitude. Another huge lethal problem for tokamaks
>and other wall solid vacuum wall confined systems is the plasma impurity
>problem.
>
concept, but all I ever seem to get are a few paragraphs scattered
about in a long post about how bad DOE is. Is there a journal article
or a technical report that I can look at that describes the
nuts and bolts of this concept and how it differs from an explosively
compressed sphereomak
...
>> there is one issue that is very important
>>and cannot be resolved reliably just from theory and numerical simulation.
>>The hot alpha particle by products have an energy of about 4 MeV. They
>>will form a very hot component to the plasma. Ideally it will heat the
>>plasma by means of Coulomb collision and/or turbulent deceleration. However,
>>there is also the possibility that these hot alpha particles may excite
>>and unstable mode of oscillation that will degrade confinement. These are
>>sometimes called TAE modes or GAE modes, etc. The acronyms stand for
>>"Toroidal Alfven Eigenmodes" or "Global Alfven Eigenmodes".
>
>That's about as likely as the moon falling into lake Michigan at dawn
>tomorrow.
willing to bet your little finger on it? :>
>
>The tokamak can be operated in the H or perhaps the Super H mode, One
>of the things that happens is that fusion generally takes place in the
>hotter portions of the plasma which are along or just peripheral to the
>minor axis. Since Tokamaks are tokamaks and not Spheromaks the toroidal
^^^^^^^^^^
don't you mean the magnetic axis?
>field is not generated by plasma currents, consequently it tends to be
>fixed. However, the toroidal plasma current tends toward tracking the
>resultant mag field which is a mixture of toroidal field and itown
>generated poloidal field. This field has helicity so the purely toroidally
>driven plasma current (initially), starts to stretch its flow along
>the helical mag flux lines. The poloidal current increases (and the
>lessened toroidal component) diminishes the magnetic helicity and the
>very much stronger rigid toroidal field snaps the plasma current back
>to be more toriodal in nature. Thus there is an increase in toroidal
>field and the whole process cycles. Since the tor-component of current
>looks a bit like a "saw tooth", because of the jerking back and forth
>in vector space, the phenomenon is named "saw tooth" action or some
>such nomenclature.
>
There's an old joke. Q: Why do tokamaks have to worry so much about
disruptions but RFP's don't? A: because RFP's are always in disruption.
The same seemed to be true of FRC's when I was talking with
experimentalists, and my inuition says that your concept will also.
This is good and bad news. The good nes is that you may get around
some instabilities. The bad news is that the transport will probably
suck. Just think about it a minute. If you have a bucket of water, is
the thermal conductivity from the center to the top increased or
decreased is you start creating "sloshing" modes to eliminate Benard
convection? of course it is increased.
>Anyway the really important result of this is that it blows away the
>99% of the theorized hot alpha induced and other disruptive effects.
>This is done because the current jerking actually jerks plasma and
>sloshes it in a vortex much like the clothes in a washing machine
>are sloshed back and forth but more importantly are swirled in a
>waltzing toroidal vortex about the spindle. For the wash every thing
>gets blasted with soap and water, not just bubbles and air, and for
>the plasma the hotter more ohmically heated minor axis is diffused
>(actually mixed) with the adjacent plasma and over a substantial
>cross-section. That reduces the thermal gradients (especially the
>thermal electron gradient) and chops into bananas and other fruits
>theorist may harass themselves with.
>
surprise, surprise, you cannot use theory based on a tokamak
ordering to analyze a device that does not obey tokamak scaling
assumptions. However, my (uninformed -- see note above) gut says
you are being just as over optimistic and overselling just as
much as the fusioneers of the 1960's/70's did with the tokamak.
Your argument appears to be that since your device is different
from a tokamak, there are some (perhaps good) reasons to expect it
to be free of some of the most troublesome problems for tokamaks.
This may be correct. However, your device may also be susceptible to
instabilities that the tokamak is immune to. For example, sphereomaks
had to deal with the tilt instability which was not a problem
for tokamaks. Just because you don't have to bear their cross, doesn't
mean you don't have your own cross to bear.
>> is very noteworthy. The history of fusion energy development is that
>>at every turn there is another "monster guarding the door". Whether it is
>>MHD instabilities, drift or other micro-instabilities, or turbulent transport.
>>As each monster has been killed (or caged) and the door it was guarding
>>opened, another monster has reared its head. Well there is not room for
>>many more monsters to exist between where we are now and ignition. Of
>>course there are very significant engineering problems yet to be tackled,
>>but that's another issue. :>
>
>And all of these monsters were but the fantasy imagination of the
>childishly developed science of plasma physics.
>
balderdash. There have been real and very large problems that have
been overcome with a great deal of perseverance and ingenuity. To
label solved difficult problems as fantasy and trivial in retrospect
is an incorrect view of history. The conception, design, and engineering
of high power neutral beam technology to deal with decreased ohmic heating
efficiency at high temperatures is a case in point. However, as you
say, if there a more promising concept was used, it may not be necessary
to face these difficult problems.
Let me just add, that it seems that Paul wants to characterize
me as an advocate of Tokamak fusion. That is not correct. I have
spent my time working on alternative (i.e. non-tokamak) concepts for
magnetic fusion. I personally believe that the tokamak will never be an
economically viable commercial reactor. However, I do believe that it is the
best hope for achieving ignition in an experiment in the near future. The
cost of ITER is justified if for no other reason than as a high
flux source of energetic neutrons to use for materials characterization
studies. The materials phase of ITER will go further toward helping
commercial fusion than anything else I see on the horizon right now.
This is true even if the final reactor is not a tokamak, or even if
it is a low neutron machine. Of course if you believe Paul, he will
give you a device that will ignite in less than 10 years with 0
neutrons. I'm from Missouri.
I am not all "gaa-gaa" over the tokamak and TFTR. I just think
that sometimes you have to give the devil its due. Last week,
TFTR produce more fusion neutron power than ever before, apparently
without unexpected troubles (which many DID expect), and there is
a program of shots over the next year to further explore and
improve these results. These are significant results. We can go back to
grinding our personal axes later. Otherwise we are no better than
the political consultants who try to manage the PR spin at every turn.
BTW,did Ed Rollins say how much he paid out in order to get the
anomalous transport gremlins not to show up for these shots? :>
-john .w cobb
Paul M. Koloc
>In article <CI2GL...@prometheus.uucp>,
>Paul M. Koloc <p...@promethe.UUCP> wrote:
>please explain. I have repeatedly asked for details of this plasmak
>concept, but all I ever seem to get are a few paragraphs scattered
>about in a long post about how bad DOE is. Is there a journal article
>or a technical report that I can look at that describes the
>nuts and bolts of this concept and how it differs from an explosively
>compressed sphereomak
The PLASMAK(tm) magnetoplasmoid (PMK) differs from a common or ideal
Spheromak in essentially two ways: It has a conduction shell of
plasma supported by an isobaric fluid (gas blanket) (and is therefore
magnetically omnigenous), and which can be compressed from one or
two atm to 10 (d-He3) to 20 katm in the case of a p-B11 burn.
SECONDLY,
the PMK is hyper*conducting due to energetic electrons.
* HYPERCONDUCTIVITY === 5 - 7 orders better than copper conductivity.
That should give you enough information to calculate their energy and
internal structure. say for a 10 cm radious ball with a boundary pressure
of 1 atm (5 kggauss) external interfacing surface of the internal vacuum
poloidal field. Remember Spheromaks have toroidal fields internal within
the central or plasma ring and this gives the beastie an aspect ratio
about 2. (apha = R/r)
Otherwise, read:
R. Roth, "Ball Lightning as a Route to Fusion Energy" Proceedings of the
IEEE, THE 13TH SYMPOSIUM ON FUSION ENGINEERING, Knoxville
(Oct. 2-6, 1989), Cat. No. 89 CH 2820-9 Vol 2, pages 1407-1411
Koloc, P. M. "PLASMAK(tm) Star Power for Energy Intensive Space
Applications" FUSION TECHNOLOGY Vol. 15, Mar 89, pp 1136-1141
>willing to bet your little finger on it? :> Who is this guy
Cobbone??? Hey if you family you tell me up front ..
>>The tokamak can be operated in the H or perhaps the Super H mode, One
>>of the things that happens is that fusion generally takes place in the
>>hotter portions of the plasma which are along or just peripheral to the
>>minor axis. Since Tokamaks are tokamaks and not Spheromaks the toroidal
^^^^^^^^^^
> don't you mean the magnetic axis?
No, I mean the minor plasma toroidal axis along which the most dense
resistive currents flow.
>>field is not generated by plasma currents, consequently it tends to be
>>fixed. However, the toroidal plasma current tends toward tracking the
>>resultant mag field which is a mixture of toroidal field and itown
>>generated poloidal field. This field has helicity so the purely toroidally
>>driven plasma current (initially), starts to stretch its flow along
>>the helical mag flux lines. The poloidal current increases (and the
>>lessened toroidal component) diminishes the magnetic helicity and the
>>very much stronger rigid toroidal field snaps the plasma current back
>>to be more toriodal in nature. Thus there is an increase in toroidal
>>field and the whole process cycles. Since the tor-component of current
>>looks a bit like a "saw tooth", because of the jerking back and forth
>>in vector space, the phenomenon is named "saw tooth" action or some
>>such nomenclature.
>There's an old joke. Q: Why do tokamaks have to worry so much about
>disruptions but RFP's don't? A: because RFP's are always in disruption.
>The same seemed to be true of FRC's when I was talking with
>experimentalists, and my inuition says that your concept will also.
>This is good and bad news. The good nes is that you may get around
>some instabilities. The bad news is that the transport will probably
>suck. Just think about it a minute. If you have a bucket of water, is
>the thermal conductivity from the center to the top increased or
>decreased is you start creating "sloshing" modes to eliminate Benard
>convection? of course it is increased.
I wasn't talking about wave sloshing where the undulations are
constrained by walls less than a 10 wave lengths, I was referring to
a torsonal rotatational slosh with a hell of a hickup.
>>Anyway the really important result of this is that it blows away the
>>99% of the theorized hot alpha induced and other disruptive effects.
>>This is done because the current jerking actually jerks plasma and
>>sloshes it in a vortex much like the clothes in a washing machine
>>are sloshed back and forth but more importantly are swirled in a
>>waltzing toroidal vortex about the spindle. For the wash every thing
>>gets blasted with soap and water, not just bubbles and air, and for
>>the plasma the hotter more ohmically heated minor axis is diffused
>>(actually mixed) with the adjacent plasma and over a substantial
>>cross-section. That reduces the thermal gradients (especially the
>>thermal electron gradient) and chops into bananas and other fruits
>>theorist may harass themselves with.
>surprise, surprise, you cannot use theory based on a tokamak
>ordering to analyze a device that does not obey tokamak scaling
>assumptions. However, my (uninformed -- see note above) gut says
>you are being just as over optimistic and overselling just as
>much as the fusioneers of the 1960's/70's did with the tokamak.
I don't think so. I don't constrain my plasma, It is ideally MHD
stable and it is essentially none resistive, once it is fully formed.
See two classic papers :
M. Bussac, H. Furth, et al., "Low-Aspect Ratio Limit of the Toroidal
Reactor: The Spheromak," IAEA CN-37, Innsbruck, 1978.
**Next paper corrects "Loosely Fitting Critereon" of previous Furth
and Bussac.
M. Rosenbluth and M. Bussac, " MHD Stability of Spheromak," Nuclear
Fusion 19, 489, 1979.
Omnigenous adiabatic heating easily raises both temperature and
density (as well as strengthens the fields to megagauss levels).
That is it compresses self similarly. The tokamak is a relative
dinosaur. If it ever could work, it would be confined to the planet
surface, no one will visit the thing since the radiation levels will
be there for a long time so it's museum appeal will be rather dismal. ,
If it can't fly I'm not interested. I would like to zip around in
space and get to Mars in 2 weeks with a load and land on the surface
not this pussy footing stuff the aneutronic power deprived NASA
employees are forced to come up with.
For example, burning p-B11 a PMK could generate 20 to 50 megawatts
of power PER CUBIC CENTIMETER, and it is the only device whose wall
could withstand such power levels, let along produce burns in
p-B11. What was the power level at PPPL 6 megwatts per cubic
METER???? OR WAS THAT FROM THE WHOLE MACHINE.
>Your argument appears to be that since your device is different
>from a tokamak, there are some (perhaps good) reasons to expect it
>to be free of some of the most troublesome problems for tokamaks.
>This may be correct. However, your device may also be susceptible to
>instabilities that the tokamak is immune to. For example, sphereomaks
>had to deal with the tilt instability which was not a problem
>for tokamaks. Just because you don't have to bear their cross, doesn't
>mean you don't have your own cross to bear.
Only spheromaks that stupidly use external mag coils instead of
a highly conducting shells to trap the poloidal flux. Of course,
Princeton PPL's S-1 (Spheromak) stands out as sporting that
feature you cite and it became a physics "issue" so the DoE give
these bandits another 5 million to solve it. Ahhh the Jardin fig
8 coils.. minimal fix I would say.. . and petty expensive.
So do I here sour grapes..??? So you have been blowing your life
being suckered by promises of vacuum fusion with solid state walls
surrounding this hotter than the suns core plasma??? Hey you have
been following plasma experiments worrying about in good vacuums ..
right??? Feel for the saps that will follow and have to work in
radiated chambers that just don't get the vacuum they need to
produce a non-disrupting plasma --- Doesn't the thought of that
tell you there must be a better way... The hottest plasma in the
universe surrounding by cryogenic coold coils .... Give us a break
DoE.
>>childishly developed science of plasma physics.
>balderdash. There have been real and very large problems that have
>been overcome with a great deal of perseverance and ingenuity. To
>label solved difficult problems as fantasy and trivial in retrospect
>is an incorrect view of history. The conception, design, and engineering
>of high power neutral beam technology to deal with decreased ohmic heating
>efficiency at high temperatures is a case in point. However, as you
>say, if there a more promising concept was used, it may not be necessary
>to face these difficult problems.
Oh really, well what if I told you that absolutely no neutral beam heating
is necessary or RF heating or laser heating or plasmoid injection or
... ... Certainly heating is needed, but the problem with tokamaks
is they just don't have the capability to do strong compression heating.
Anyway, a tokamak has a pressure limit...da da ...like a horse tank if
you keep filling and filling it with power (water) sooner or latter it
will fill up and your energy will start leaking out as fast as you pump
it in..
That's because pressure or force per unit area is equivalent to energy
per unit volume. Your toroidal mag field can sit there at 1 kilobar and
less than 1% of that pressure (far less >>) is in the plasma nkT.
So, if the max pressure you can hold is 8 atmospheres then all of
the beam this and that heating you do won't be capable of improving the
situation. It's like pumping heat into a kettle of water.. after it
starts boiling .. magically it doesn't go up in temperature much well
essentially not at all. So friend what toky fellows need is to
get a real pressure cooker. One that when you do apply external
pressure you will end up with more internal plasma nkt pressure then
you have applied externally, rather than less than 1%...
Gee, that's a hell of a way to use a highly leveraged lever and fulcrum
.... BACKWARDS.
But as they say only at PPPL ...
So, Please preserve a tokamak by NOT putting tritium in it so that
the future may have a place to go to see the utter stupidity of
physicists trying to impose there engineering ability on a project.
And have a scene of a Cave Dweller prying a boulder away from the
entrance to his cave --- correctly using a lever and fulcrum ..
Then the same scene with a DoE employee .. Ann DAvies..?? attempting
the same with stone rolled onto her drive way, .. but this time she
is holding the "short end of the sticK" ... so to speak.
This is just so the kiddies get the picture of what went wrong here.
Yep when you want to do a job, make certain an engineer is running
things. Of course, an engineering physicist* would be best ....
This comment may be considered self serving.
>Let me just add, that it seems that Paul wants to characterize
>me as an advocate of Tokamak fusion. That is not correct. I have
>spent my time working on alternative (i.e. non-tokamak) concepts for
>magnetic fusion. I personally believe that the tokamak will never be an
>economically viable commercial reactor. However, I do believe that it is the
>best hope for achieving ignition in an experiment in the near future. The
>cost of ITER is justified if for no other reason than as a high
>flux source of energetic neutrons to use for materials characterization
>studies. The materials phase of ITER will go further toward helping
>commercial fusion than anything else I see on the horizon right now.
>This is true even if the final reactor is not a tokamak, or even if
>it is a low neutron machine. Of course if you believe Paul, he will
>give you a device that will ignite in less than 10 years with 0
>neutrons. I'm from Missouri.
Well ... O is a mighty tiny number but howabout negligible or let's
for comparison less than one per cent of the radiation generated by
the radon released by an equivalent energy producing amount of coal??
Fair enough.. First we must be funded to do a commercial burn and
then in 4 years, or five max we will do the burn. The p Boron will take
more time by 10 years is about right from the initial outlay of the the
D-He3 burn support.
Certianly We will burn D-He3 in 1/10th the time with 1/100th the
money and it will be an aneutronic COMMERCIAL break-even burn.. The
only lethal detail here is .....that 1/100th the funds. Further,
the product device will be high density power, compact and useful
for space power and propulsion. This has been a commercial for .. .
>I am not all "gaa-gaa" over the tokamak and TFTR. I just think
>that sometimes you have to give the devil its due. Last week,
>TFTR produce more fusion neutron power than ever before, apparently
>without unexpected troubles (which many DID expect), and there is
>a program of shots over the next year to further explore and
>improve these results. These are significant results. We can go back to
>grinding our personal axes later. Otherwise we are no better than
>the political consultants who try to manage the PR spin at every turn.
>BTW,did Ed Rollins say how much he paid out in order to get the
>anomalous transport gremlins not to show up for these shots? :>
Whoa! first of all it it did not achieve anything near the original
goals that were set for it. Not even close. Read Davisson's Poster
It iss good you are positioning yourself for a softer landing.
>-john .w cobb
An Engineering Physicist
is to big sci projects
What a quarterback is
to a football game.
One has to be able
to see the whole field at once
and to find a path that
misses the difficult problems
Doe seems to be
running this
fusion game
from VIP Lounge
John W. Cobb
Paul M. Koloc <p...@promethe.UUCP> wrote:
>>In article <CI2GL...@prometheus.uucp>,
>>Paul M. Koloc <p...@promethe.UUCP> wrote:
>
>>please explain. I have repeatedly asked for details of this plasmak
>>concept, but all I ever seem to get are a few paragraphs scattered
>>about in a long post about how bad DOE is. Is there a journal article
>>or a technical report that I can look at that describes the
>>nuts and bolts of this concept and how it differs from an explosively
>>compressed sphereomak
>
>Spheromak in essentially two ways: It has a conduction shell of
>plasma supported by an isobaric fluid (gas blanket) (and is therefore
>magnetically omnigenous), and which can be compressed from one or
>two atm to 10 (d-He3) to 20 katm in the case of a p-B11 burn.
>
> SECONDLY,
>the PMK is hyper*conducting due to energetic electrons.
>
> * HYPERCONDUCTIVITY === 5 - 7 orders better than copper conductivity.
>
>That should give you enough information to calculate their energy and
>internal structure. say for a 10 cm radious ball with a boundary pressure
>of 1 atm (5 kggauss) external interfacing surface of the internal vacuum
>poloidal field. Remember Spheromaks have toroidal fields internal within
>the central or plasma ring and this gives the beastie an aspect ratio
>about 2. (apha = R/r)
>
Paul. This sounds very interesting. I now have some bedtime reading
for a while. Thanks,
Actually, it sounds startlingly similar to an idea I worked on for a
a short while a few years ago. Basically, the idea was that you could
set up a similar solition structure like a Sphereomak. It would have a
non-zero wall pressure like your plasmak idea seems to (but not thousands
of atmospheres).
The first thought is that the pressure allows a good mechanism for
confinement (provided you don't mind having a liquid first wall).
But there is a really neat trick. Usually one has to live with the
need for external coils becuase "as everyone knows" a plasma cannot
be contained by use solely of its own magnetic field. This is the
virial theorum argument that Shafranov uses to prove it in his Rev.
Pl. Phys. article. However, in that argument, there is an assumption
that you can integrate over a control volume that is large enough so
that it contains all pressure gradiants.
Sooo, the free lunch idea is that maybe you can create equilibria
that have very very low external magnetic fields and therefore only
a need for very small extenral coils. This is the soliton reactor, or
"magnetic fusion without magnetics" idea.
It is written up briefly in the Institute for Fusion Studies Report
number 474 "Toroidal Plasma Reactor with a Low External Magnetic Field"
by Beklemishev, Gordin, Kharutdinov, Petviashvili, and Tajima.
Maybe you can use some of these ideas in the PLasmak. ---- hmmm.
Paul M. Koloc
>In article <CI4Hs...@prometheus.uucp>,
>Paul M. Koloc <p...@promethe.UUCP> wrote:
>>In article <2enbls...@emx.cc.utexas.edu> john...@emx.cc.utexas.edu (John W. Cobb) writes:
>>>In article <CI2GL...@prometheus.uucp>,
>>>Paul M. Koloc <p...@promethe.UUCP> wrote:
>>The PLASMAK(tm) magnetoplasmoid (PMK) differs from a common or ideal
>>Spheromak in essentially two ways: It has a conduction shell of
>>plasma supported by an isobaric fluid (gas blanket) (and is therefore
>>magnetically omnigenous), and which can be compressed from one or
>>two atm to 10 (d-He3) to 20 katm in the case of a p-B11 burn.
>>
>> SECONDLY,
>>the PMK is hyper*conducting due to energetic electrons.
>>
>> * HYPERCONDUCTIVITY === 5 - 7 orders better than copper conductivity.
>>
>>That should give you enough information to calculate their energy and
>>internal structure. say for a 10 cm radious ball with a boundary pressure
>>of 1 atm (5 kggauss) external interfacing surface of the internal vacuum
>>poloidal field. Remember Spheromaks have toroidal fields internal within
>>the central or plasma ring and this gives the beastie an aspect ratio
>>
>>Otherwise, read: ...
>
>Paul. This sounds very interesting. I now have some bedtime reading
>for a while. Thanks,
>
>Actually, it sounds startlingly similar to an idea I worked on for a
>a short while a few years ago. Basically, the idea was that you could
>non-zero wall pressure like your plasmak idea seems to (but not thousands
>of atmospheres).
>The first thought is that the pressure allows a good mechanism for
>confinement (provided you don't mind having a liquid first wall).
Actually, liquid DENSITY, but it IS IN THE PLASMA STATE at the PMK
Mantle always and throughout the blanket after burn.
>But there is a really neat trick. Usually one has to live with the
>need for external coils because "as everyone knows" a plasma cannot
>be contained by use solely of its own magnetic field.
Technically, this is not true, as stated. What is true is that
"external PRESSURE" is needed regardless of form.
That is magnetoplasma, plasmomagnetic, pneumatic, piston, etc. etc.
Problem is that program managers have a serious want of imagination.
So the DoE PMs think magnetic fields are only to be created by
currents within solid rigid coils and not from anything else!!.
They would still be doing the currentless Stellarators if the
Russians didn't at least convert one coil current to a plasma
current (became the tokamak).
Technologically mag fields are a sort of pressurized (vector) fluid.
> .. . This is the
>virial theorum argument that Shafranov uses to prove it in his Rev.
>Pl. Phys. article. However, in that argument, there is an assumption
>that you can integrate over a control volume that is large enough so
>that it contains all pressure gradiants.
But that is because it assumes another thing that there are
essentially NO or are ignorable pressure boundaries. For example
a toroidal field generated by poloidal currents on nested toroidal
surfaces would have tensile strength only along the flux lines in
each current surface. But in the orthogonal direction there is no
tensile strength so the current surface is free to expand limitlessly.
That is, a donut surface stuffed only with toroidal magnetic pressure
has an expansion growth in the minor radial direction. So the donut
tends to be short and fatter and fatter. Since the field lines wrap
the longway around inside the toroid but around its major axis,
The toroid's major circumference is impeded from growth, while its
minor radius is free to grow to its limit which depends on its
magnetic field's orientation. Certainly the shape would become
more and more like a racing bicycle tire. The relative aspect ratio
alpha is:
alpha = Major Radius/minor radius
If the plasmoid had a poloidal field then a toroidal tube of
current only generates flux outside the current tube and that
flux encircles the torus around its minor radius. With only
this field present a plasmoid ring bearing current toroidally
will tend to expand along the major radius so shape is altered
toward a larger diameter wheel with a much narrower rim, thus
a more racing bicycle tire look.
The most interesting case is that of the Spheromak class of
plasmoids. This is because a current carrying nested toroidal
tube now carries a resultant heliform current meaning it has
both poloidal and toroidal currents. That gives rise to two
orthogonal mag vectors fields which can't add since one is
on the outside (poloidal) and the other is only in the inside of
each hyperconducting current tublet. Consequently, the fields
can't mix!!! No valid Dot product here!!!
So what's up???
Well this. The virial theorem is an oxymoron, that is it is not
a theorem, and it's not very virile. That is it is really an
engineering rule of thumb which is a special case of the
divergence theorem applied where there are no " SOURCES or SINKS"
"S&S" (pressure bearing surfaces) within the region.
To apply the Virial Theorem correctly, the region of integration
over the surface containing the volume of interest must have an
absence or want of S & S. Further the outer perimeter must be
knownable, constant and accessible and the only source of
pressure. The first two cases (poloidal, only or toroidal field
only) qualify since no pressure bearing surfaces (no two
dimensional tensioned surfaces) exist. For example STP air
surrounds BL plasmoids, and has an energy density of ~ 1joule/cc.
Vertical magnetic fields are also constant (beyond the
separatrix).
Now the trouble comes with the Spheromak like configuration which
does have enhanced Beta stars or higher internal pressures, etc.
etc. all signs that the usual glib answer from VT doesn't apply.
First of all let's look. The Spheromak/PLASMAK(tm) Magnetoplasmoids
clearly contain within them a Kernel plasma which has a pressure
bearing surface. For simplicity assume that all the currents flow
on a single toroidal surface in the Kernel plasma. In this, as above
there is an internal toroidal field with the flux lines bearing
pressure against the poloidal component of current in the current
surface and there is an external poloidal flux which bears pressure
against the toroidal component of current in the Kernel toroid shell.
So we have a pressure bearing surface with strands of imbedded
orthogonal tensile strength. We have a magnetoplasma surface
tension toroidal bubble. Now the toroidal field links the poloidal
field and vice versa.
So we are stuck, because the pressures, though equalibrated over the
current surface at each point and axis-symetric to the major axis
are still not uniform over the surface. The innermost innerface
of equatorial circumference (around the inside of the hole of
toroid) has poloidal outside torus) and toroidal (inside torus)
interfacing each other with a common pressure bearing current
sheet between them. The electrons have essentially no force so the
pressure equilibration is down by volume adjustments of the flux
on either side.
However, there is another equatorial circumference. This is the one
which is outer most to the current toroid. The pressures equilibrate
here too. However, the pressure is much less on this one than the
inner must one (about 25% for an aspect ratio 2 Spheromak/PMK),
But elsewhere we aren't so sure what the pressure or energy density
values are so we are toast as far as fixing up and still trying
to use the virial theorem. We simply must fall back and use
the full Divergence theorem; here do the volume integration over
each contribution. .
That means we can NOT and do NOT use the virial theorem and we do
go directly to the divergence theorem. Models may be now more
sophisticated and require this procedure more often, but with today's
desktop computing power in 10% of the computing households there
exists plenty of computational power to solve this problem to
a reasonable accuracy. So at last, the occasional inappropriately
utilized virial theorem can finally take a break.
>Sooo, the free lunch idea is that maybe you can create equilibria
>that have very very low external magnetic fields and therefore only
>a need for very small external coils. This is the soliton reactor, or
>"magnetic fusion without magnetics" idea.
Remember we need density, Temperature and the hold time for fusion
temperatures and densities to exist. . T* n is pressure. (nkT) if
we add Boltzsman's contribution. So this fluffy approach isn't
going to work very well; certainly won't work in the long run.
Actually, current flowing in any conducting surface will generate
a field, or if I open a soda can, clean it out, dunk it in liquid
N2 and drop an osmium magnet into the hole in the top of the super
cooled can, I can momentarily trap flux in the can. That current
in the walls is called an image current, but it is real and opposite
in circulation to the "virtual currents generating" the mag fields
in the osmium magnet.
The mag field of the magnet acts like a vector or flow field
of gas moving out through space, around and back again on the
back end. It can be thought of as generating pressure on any
conducting surface, whether it be a source or a sink (better a
magnetic field neutralization current. Anyway the point is this
"gas" like character will generate a "pressure" on the walls of
the chilled aluminum can when the magnet is dropped in.
If the Al walls were a perfect conductor than the field would be
trapped in there for a long time and would float as far from the
walls as it could get and that's the middle. The same is true
of the PMK's Kernel, since it "floats and lodges in the middle"
and bounces around restoratively if the Mantle is bounced off
things and changes direction suddenly. Magnetic insulation
makes it cushy and with the drag of the Mantle -- very stable.
In order for Shafranov to do the problem he assumed a lazy (more
bicycle tire like) toroidal topology. This was so the pressure
differences between the inner and outer surfaces would be
ignorable. And that was so he didn't have to use a computer.
Too bad, because there is not much difference between a weak
torus in air and a smoke ring.
Still this configuration is unique, since with both toroidal
and poloidal components, only the slightest bath of isobaric
gas pressure was sufficient to bring the system to stability.
Of couse as he pointed out, the neutral particle diffusion into
the torus would generate catastrophic disruptions quickly. That's
why it is important to keep the atmosphere off the Kernel plasma.
He gave up too quickly on this core idea as a BL concept, and
never added the concept of the Mantle. That will teach him not
to take a bit of astronomy or geology.
Then with very very high magnetic poloidal pressure a very dense
atmosphere can be hung on the external poloidal flux surface, as
is the case in magnetic stars. No! I don't think the gentle
sea breeze pressures are going to turn this trick.
>It is written up briefly in the Institute for Fusion Studies Report
>number 474 "Toroidal Plasma Reactor with a Low External Magnetic Field"
>by Beklemishev, Gordin, Kharutdinov, Petviashvili, and Tajima.
>Maybe you can use some of these ideas in the PLasmak. ---- hmmm.
Well I thought through this stuff a few yaron back. But thanks
for the suggestion
Keep slogging.
Matt Kennel
: Why does everyone keep talking about the amount of energy output,
: instead of the ratio of input energy to output energy. I see no
: reason to get excited about the fact that you can input 30(?)MW and
: get back 5.5, unless the ration 5.5/30 is a new record. (Is it?)
Yes.
: Otherwise, all people have to do to get in the news is keep building
: bigger versions of reactors that are no closer to break-even than
: previous ones -- they're just bigger, so the absolute output is higher.
Tokamak losses scale vaguely as the surface area, but power scales
as the volume.
: --
: Michael Condict con...@osf.org
: OSF Research Inst. (617) 621-7349
: 1 Cambridge Center
: Cambridge, MA 02142
--
-Matt Kennel m...@inls1.ucsd.edu
-Institute for Nonlinear Science, University of California, San Diego
-*** AD: Archive for nonlinear dynamics papers & programs: FTP to
-*** lyapunov.ucsd.edu, username "anonymous".
Thad Wilson
>instead of the ratio of input energy to output energy. I see no
>reason to get excited about the fact that you can input 30(?)MW and
>get back 5.5, unless the ration 5.5/30 is a new record. (Is it?)
>Otherwise, all people have to do to get in the news is keep building
>bigger versions of reactors that are no closer to break-even than
>previous ones -- they're just bigger, so the absolute output is higher.
>Paul Koloc, please give us your assessment of this news.
Will someone respond to this!!! The way the press played this thing you
