[Paul Werbos]

At his moment, the US Secretary of Energy is making an important announcement on fusion energy. 

I thank Ajay for alerting me to this announcement.Below, I append my initial quick response.

BRIEFLY:

This **IS** extremely important to space, and even to US-India relations.

In a conference at Ohio Aerospace Institute, organized by John Mankins (for our joint activity JIETSSP, led by me at NSF), Richard Fork and I presented a new laser design for fusion in space,

based on a long collaborative discussion of the issues.

Fork is also active in space power transmission 

https://ntrs.nasa.gov/api/citations/20060024813/downloads/20060024813.pdf. He even invited me to the birthday party of his old teacher, Willis Lamb, of the Lamb shift, who knew things few physicists have caught up with even now. 

(As I type, Livermore is telling us how machine learning was a crucial piece of this. They used algorithms I developed, which explains why they invited me to India and asked me to write up what I told them. New paper attached, major connection in India.)

BUT: the D-T targets and earth system they are announcing... yes, it's better than tokomaks. But the real problem is the huge emission of neutrons, huge cost of lasers on earth, and national security issues beyond what you may imagine. Even earth-based NIF is a loser, bottom line. The lazy way, keeping it simple stupid, is a loser. 

BUT IN DEPTH, THIS IS A HUGE STEP FORWARD, IF WE ARE SMART ENOUGH TO ADD SPACE, ADD D-D

On my hard drive, I have many many detailed papers from Perkins of LLNL reporting on their work on use of D-D pellets instead of D-T. Get rid of even 20-30% of the neutrons, and do it in space, and the biggest problems disappear instantly. When neutrons fly in  space, they turn into  protons in like 10-15 minutes. Furthermore, even the Fork-Werbos design for a space laser would result in power beamed to earth, at  a cost much lower than the SPS Alpha number. I described some of the basics in many of my later published papers.

You can find the basics even now in slides I gave to ISDC conferences,

You might ask: IF I am coauthor of the lowest cost credible SSP option, why didn't I work harder to get the word out?

First, mea culpa. This is one of a VERY long list of my sins of omission and of mediocre communication skills. It takes a village, and one old guy on his own is not a village. 

Second, this will be many times cheaper than SPS Alpha after the new space laser is proven out, but that has yet to be done, and BOTH are too expensive for real markets UNTIL AND UNLESS WE PUT REAL ENERGY INTO ACCESS TO SPACE MUCH CHEAPER THAN THE SNAIL (SpaceX as it still crawls along even now). Some of us know how; thanks to those on this list who do. My hard drive has very deep documentation on how, from the days when I at NSF was one of the three US funders of research to understand and replicate advanced hypersonics technology developed in Russia.  I gave that priority over my own more advanced idea, because it's good enough to make SPS Alpha market-worthy and we need it urgently.

HOWEVER -- MORE AND BETTER RD&D ON D-D laser fusion in space would be a good national investment now for many reasons, buying us more of the evidence we need to justify the better space transportation. 

FOR THOSE WHO WANT A QUICK SUMMARY OF THE FULL, HARD REAL STORY:

In my very first talks to old ISDCs, supporting SSP, I emphasized national security more than energy supply and climate as a justification. (That was before the new science came in on climate extincion, as posted on Gary's website build-a-world.org.) 

For three years, I was the interagency coordinator of the main US government research to understand and combat nuclear proliferation and terrorism

https://www.nsf.gov/pubs/2013/nsf13554/nsf13554.htm. In truth, that interagency effort was created by a woman Kathie Olsen whom I knew well, who never knew how deeply I once loved her -- but I stopped trying to know her better after I met my present wife, who knew this nuclear stuff more than anyone else I cite here or bcc. The previous coordinates served for only one year, but they wanted me to stay even longer because I go very deep into it. HOWEVER, I never write any more about the most serious stuff because -- guess what -- nuclear extinction is on my short list of worst fears, things that really threaten to kill all humans as soon as this century. After extensive review, I WAS able to give away about 5% of what I learned

for use in a NATO conference and book, also posted at: werbos.com/NATO_terrorism.pdf.

And so... the  neutrons are a problem. But so is every form of fission on earth. And so are the kinds of humans who try to put pressure on us to prove the case by spelling out exactly how to kill every human on earth. I regret how much I gave away on arxiv before I learned better. 

I have hoped that a reliable, more permanent but open archive could take all the relevant material on my hard drive, and help create the necessary pointers and access. 

We have reached a time when we have to take small risks to reduce larger risks. But I don't think the very scariest is even there. 

After I created the NSF/NASA JIETSSP effort, I contacted Perkins of Livermore to explore a new joint initiative on the DD-space SSP option, focused on finding a better laser design.

One day, on an airplane, I spoke to the RIT guy coming back from Perkins, to get into more details. To my surprise, he said that China was actually far ahead of the US in the relevant kind of laser. One of my activities at NSf ("QMHP") also got into that, and I once funded Suckewer of Princeton to fund his space laser concept for debris cleaning, in collaboration with 

Peter Garretsn. We had many ideas. But the politics never worked out. The RIT guy also told me: "The real problem NOW is with the target design. That is also more of a national security issue." In fact, except for the nuclear forces, it was a classic QMHP modeling challenge. (QMHP often used tools from Schwinger, one of my old teachers.) 

I am not at all surprised it took them longer than expected, as they needed to improve their models. But now, the breakthrough is real.

Re India -- a big subject. Peter Garretson made a big impression on Abdul Kalam, a deeply revered President of India, who came to ISDC and spoke with several of us.

On Mon, Dec 12, 2022 at 7:37 PM a.p.kothari astrox.com <a.p.k...@astrox.com> wrote:

https://www.cnn.com/2022/12/12/politics/nuclear-fusion-energy-us-scientists-climate/index.html

To be announced tomorrow by DoE.

'Yes, it is important. My ex-wife sent me details. My reply:  [Comment: ex-wife does not know nuclear stuff.]

==========================

This story is real, good news, news we expected earlier but it is big nonetheless. I can even guess why it took them a bit longer than expected.

.....

I actually worked some with Perkins, the key guy at Livermore for the most important NIF work, making it work on deuterium pellets,

which, used in space, offer the safest and cheapest option in sight for mass electricity. Why space? Well, on earth, the neutrons are a disaster,

and terrorism is what I ran the main interagency R&D program on.  

(https://www.nsf.gov/pubs/2013/nsf13554/nsf13554.htm. I ran it for three years; previous coordinators were asked to rotate after a year. They tried to get me to stay on even longer, but ...) 

But politics are blocking affordable US access to space for ANYTHING now... Musk versus SLS is a race between a snail and a clam.

=====================

Best regards, Paul

 

-------------------------------------------------------
Dr. Ajay P. Kothari
President
Astrox Corporation
 AIAA Associate Fellow

Ph: 301-935-5868
Web:  www.astrox.com
Email: a.p.k...@astrox.com
-------------------------------------------------------

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Subject: SDSC Meeting Today!!!

This is just a friendly reminder for SDSC meeting will be held Monday
9:00 PM EST please confirm your attendance. Thank you all!!!


Description: The Space Development Steering Committee Weekly

please see Meeting link below:

https://www.uberconference.com/room/howlbloom, code 06384 then hit the
pound and announce yourself to the assembled multitudes.

[Jerome Glenn]

How long was sustained fusion maintained?

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[a.p.kothari astrox.com]

5 seconds.

 

-------------------------------------------------------

Dr. Ajay P. Kothari

President

Astrox Corporation

 AIAA Associate Fellow

 

Ph: 301-935-5868

Web:  www.astrox.com

Email: a.p.k...@astrox.com

-------------------------------------------------------

 

To view this discussion on the web visit https://groups.google.com/d/msgid/power-satellite-economics/085e01d90f1e%24bf787b80%243e697280%24%40igc.org.

[Keith Henson]

On Tue, Dec 13, 2022 at 9:02 AM Paul Werbos <paul....@gmail.com> wrote:

snip

> BUT IN DEPTH, THIS IS A HUGE STEP FORWARD, IF WE ARE SMART ENOUGH TO ADD SPACE, ADD D-D

I am totally lost here. Please understand that I am a big fan of
fusion and there are places where it makes more sense than anything
else.

But for energy on earth, I just can't see the economics of putting
fusion power plants in space. First, you lose half the energy in
transmission, second, the energy concentration is a relatively small
part of the mass of a power satellite, the radiators, even my light
ones, are more massive.

Perhaps I just don't understand at some block diagram level.

snip

> Furthermore, even the Fork-Werbos design for a space laser would result in power beamed to earth, at a cost much lower than the SPS Alpha number. I described some of the basics in many of my later published papers.

At present, I am looking into a 10-12 GW propulsion laser. I have
been scaling the design from the even larger DE STAR laser of Philip
Lubin (UCSB). My cost estimates, based on the capital involved, are
around 10 times the cost of power from a power satellite.

If there is a way to make laser power cheaper than the 3 cents per kWh
(or even 10 cents per kWh) it would change the economics of space
transportation beyond recognition.

> You can find the basics even now in slides I gave to ISDC conferences,

Can the ideas be expressed in a short paragraph? Given that the
economics of power satellites are driven by kg/kW and $/kg to orbit,
what is the kg/kW for DD fusion in space?

Keith

[Keith Henson]

On Tue, Dec 13, 2022 at 10:15 AM a.p.kothari astrox.com
<a.p.k...@astrox.com> wrote:
>
> 5 seconds.

That may be the case, but it just sounds very wrong to me.

Keith

> To view this discussion on the web visit https://groups.google.com/d/msgid/power-satellite-economics/MW4PR04MB7362EFC16836C438183A41B1C5E39%40MW4PR04MB7362.namprd04.prod.outlook.com.

[Tim Cash]

I am sorry, I am just too cynical, far too cynical to believe that the Fusion Geniuses will pull this secret new sauce out of their back pocket at the last minute to save Planet Earth!

I need proof, direct proof, in front of me, no smoke, no mirrors, nada, just beyond break even power output.  Just like Power Beaming 1975, power a bank of LCD or LED with the power from fusion.

If this is true, do we discard all of our current efforts with Space Solar Power, or just put it in our back pocket?

I have been forced to believe in the viability of quantum engineering, even though it still does not smell right to me.

They certainly have spent enough money to make it work, that much is for sure.

To view this discussion on the web visit https://groups.google.com/d/msgid/power-satellite-economics/CAPiwVB7uhoJRszPUxqXLij8%3DMjTDEENfVxp8yOb57T%3Du32jO8A%40mail.gmail.com.

--

Tim Cash

cash...@gmail.com

[a.p.kothari astrox.com]

Wait. The event occurred in 100 trillionth of a sec.

 

 

-------------------------------------------------------

Dr. Ajay P. Kothari

President

Astrox Corporation

 AIAA Associate Fellow

 

Ph: 301-935-5868

Web:  www.astrox.com

Email: a.p.k...@astrox.com

-------------------------------------------------------

 

From: power-satell...@googlegroups.com On Behalf Of Jerome Glenn

Sent: Tuesday, December 13, 2022 1:15 PM

To view this discussion on the web visit https://groups.google.com/d/msgid/power-satellite-economics/085e01d90f1e%24bf787b80%243e697280%24%40igc.org.

[Keith Henson]

"The experiment Dec. 5, at the Lawrence Livermore National Laboratory
in California, took a few billionths of second. "

Best wishes,

Keith

> To view this discussion on the web visit https://groups.google.com/d/msgid/power-satellite-economics/MW4PR04MB73629CF444886C38034BE6CAC5E39%40MW4PR04MB7362.namprd04.prod.outlook.com.

[a.p.kothari astrox.com]

Thanks Paul for your thoughts. I will read your attached paper soon. I watched the whole presser.

https://www.youtube.com/watch?v=Eke5PawU7rE&ab_channel=U.S.DepartmentofEnergy
2.05 MW in, 3.1 MW out (of course the wall-plug energy still at 300 MW which will get smaller with time and efficiency of laser production. Not the intent today). This is inertial confinement. Some others are pursuing Tokamaks. All good.

The Q I have is this. Was there a chain reaction here or just fusion of the D-T atoms contained in the pellet? Any opinions?
D-T fusion releases ~17.6 MeV per atom (11 times smaller than fission per atom but 3-4 larger per unit mass).
We don’t know how many were in the pellet, or the mass thereof. Does anyone?

[Roger Arnold]

Thanks, Ajay, for posting that link to the news conference.

In answer to your question, yes, of course there was a chain reaction -- albeit with rather short chains. This was inertial confinement fusion, compressing a tiny BB of deuterium and tritium to a sufficient density and temperature to ignite with fusion energy. The individual fusion events that occurred in the first picoseconds of the laser-induced explosion transferred enough energy to other nuclei within the hot compressed BB to trigger additional fusion events. The gain wasn't very large. The explosion, according to the announcement, released 3.1 MJ (megajoules, a measure of energy, not MW, a measure of power), of which 2.05 MJ was supplied by the triggering laser pulse. So, a gain of 1.05 MJ from the micro fireball itself. (I could be wrong about that; it may be that the 3.1 MJ from the explosion was all from induced fusion events, and didn't include the 2.05 MJ from the laser pulse. In fact, as I think about it, that's probably the case. 1.05 MJ of induced fusion events wouldn't qualify as true scientific break-even.)

They'll need to improve the yield by around a factor of 1000 or more before they can claim engineering breakeven. Those pulsed laser banks consume a hell of a lot more energy than what ultimately gets deposited onto the fusion target.

To view this discussion on the web visit https://groups.google.com/d/msgid/power-satellite-economics/MW4PR04MB7362FA502B09E5F765B769FCC5E39%40MW4PR04MB7362.namprd04.prod.outlook.com.

[Paul Werbos]

On Tue, Dec 13, 2022 at 2:12 PM a.p.kothari astrox.com <a.p.k...@astrox.com> wrote:

Thanks Paul for your thoughts. I will read your attached paper soon. I watched the whole presser.

  I did pretty much the same, even as I was typing. 

https://www.youtube.com/watch?v=Eke5PawU7rE&ab_channel=U.S.DepartmentofEnergy
2.05 MW in, 3.1 MW out (of course the wall-plug energy still at 300 MW which will get smaller with time and efficiency of laser production. Not the intent today). This is inertial confinement. Some others are pursuing Tokamaks. All good.

Tokomaks are further. I am not so hopeful about them, given what neutrons and cost do to THEM.

The Q I have is this. Was there a chain reaction here or just fusion of the D-T atoms contained in the pellet? Any opinions?

Those papers from LLNL on my portable drive give some indication. To START the fusion, small bits of fission were involved. But since it works now, and didn't then , some parameters must have changed, maybe even a fator of two. Or more. I haven't seen the new papers.

But even an order of magnitude would not change the basic trade offs, or the assessment I just sent you all.

 

D-T fusion releases ~17.6 MeV per atom (11 times smaller than fission per atom but 3-4 larger per unit mass).
We don’t know how many were in the pellet, or the mass thereof. Does anyone?

Your 3-4 factor is important. The inputs we got from LLNL, USING deuterium fuel, predicted something like 0.2 cents per kwh, for the fuel cost, assuming pellets delivered to power stations in space at the same cost SPS Alpha assumed to get to 10 cents per kwh. Transmission cost to earth then becomes more important, but not enough to invalidate the basic conclusion.

[Paul Werbos]

On Tue, Dec 13, 2022 at 1:17 PM Keith Henson <hkeith...@gmail.com> wrote:

On Tue, Dec 13, 2022 at 9:02 AM Paul Werbos <paul....@gmail.com> wrote:

snip

> BUT IN DEPTH, THIS IS A HUGE STEP FORWARD, IF WE ARE SMART ENOUGH TO ADD SPACE, ADD D-D

I am totally lost here.  Please understand that I am a big fan of
fusion and there are places where it makes more sense than anything
else.

But for energy on earth, I just can't see the economics of putting
fusion power plants in space.  First, you lose half the energy in
transmission,

If cost per kwh is doubled by transmission, that is a small effect compared to building lasers many orders of magnitude more expensive. Simple real estate costs and rules around Livermore are a big part of THOSE costs! 

Not to mention the cost of mega capacitor banks, not needed for the space version. 

 

second, the energy concentration is a relatively small
part of the mass of a power satellite, the radiators, even my light
ones, are more massive.

Heat flow was a major part of what Fork and I figured out how to fix, with our joint design.

ANY big laser in space does face thermodynamic issues, for sure, but Fork was an expert on such things,

and I even know a bit about condensed matter entropy functions myself. 

**IF** there had been a joint NSF/LNLL research initiative, we certainly would have probed deeper, not because there were no fixes but because the choice of what might be most economic and how to manage the spiral development decision trees should be better understood, sooner or later. But is the best the enemy of the good right now, for this? I don't know. 

[a.p.kothari astrox.com]

Sorry about writing MW. I meant energy unit i.e. MJ.

As per the other part, 3.1 MJ total out can also be just from each individual fusion. Not necessary that chain reaction occurred.

Basically:

17.6 MeV * 6.022 exp23 (Avogadro # per gmole) * (D-T) mass in gmole * 1.6022 exp(-13) (J/MeV)

={170 exp10 * (D-T) in gmole} in Joules

If this number was 3.1 MJ, then the fusioned D-T itself was 1.8 exp(-6) gmole?

Very small. Micrograms.

I think this is a proof of fusion (Which I do believe is HUGE). Not of sustained chain reaction. That would probably would last a lot longer than a few billionth of seconds. It would have to.

IMO.

 

-------------------------------------------------------

Dr. Ajay P. Kothari

President

Astrox Corporation

 AIAA Associate Fellow

 

Ph: 301-935-5868

Web:  www.astrox.com

Email: a.p.k...@astrox.com

-------------------------------------------------------

 

[Keith Henson]

On Tue, Dec 13, 2022 at 2:23 PM Paul Werbos <paul....@gmail.com> wrote:
>
> On Tue, Dec 13, 2022 at 1:17 PM Keith Henson <hkeith...@gmail.com> wrote:
>>
>> On Tue, Dec 13, 2022 at 9:02 AM Paul Werbos <paul....@gmail.com> wrote:
>>
>> snip
>>
>> > BUT IN DEPTH, THIS IS A HUGE STEP FORWARD, IF WE ARE SMART ENOUGH TO ADD SPACE, ADD D-D
>>
>> I am totally lost here. Please understand that I am a big fan of
>> fusion and there are places where it makes more sense than anything
>> else.
>>
>> But for energy on earth, I just can't see the economics of putting
>> fusion power plants in space. First, you lose half the energy in
>> transmission,
>
> If cost per kwh is doubled by transmission, that is a small effect compared to building lasers many orders of magnitude more expensive. Simple real estate costs and rules around Livermore are a big part of THOSE costs!
> Not to mention the cost of mega capacitor banks, not needed for the space version.

I am still lost. Inertial fusion takes a huge burst of laser energy,
in the case of the LL facility, the energy goes from capacitors to
flash lamps to laser glass. What is storing the energy in space? I
am aware of lasers that are reported to be pumped with sunlight, but
this does not give a pulse.

>>
>> second, the energy concentration is a relatively small
>> part of the mass of a power satellite, the radiators, even my light
>> ones, are more massive.
>
> Heat flow was a major part of what Fork and I figured out how to fix, with our joint design.
> ANY big laser in space does face thermodynamic issues, for sure, but Fork was an expert on such things,
> and I even know a bit about condensed matter entropy functions myself.

I am somewhat knowledgeable on this topic myself, having invented a
zero-g, low-temperature (20 deg C) steam-filled radiator that masses
just over a kg/kW and scales to GW. Your explanation still makes no
sense to me. As far as I know, nobody can beat the Stefan–Boltzmann
constant, which means huge and heavy radiators to get rid of several
GW of waste heat.

Keith

[Paul Werbos]

On Tue, Dec 13, 2022 at 7:11 PM Keith Henson <hkeith...@gmail.com> wrote:

I am still lost.  Inertial fusion takes a huge burst of laser energy,
in the case of the LL facility, the energy goes from capacitors to
flash lamps to laser glass.  What is storing the energy in space?  I
am aware of lasers that are reported to be pumped with sunlight, but
this does not give a pulse.

The design included large semiconductor material type disks,

a typical optical condensed matter structure. Our correspondence and details are on the portable hard drive files, very extensive., and in the Fork/Werbos paper for the OAI conference. 

The thermodynamics are based on the generalized Boltzmann probability density operator given in Chaikin's book on Condensed Matter Physics, which the high energy folks seem to miss in scary ways (like when evaluating quantum Information D&T).

The waste energy, which does not contribute to the big optical pulse being generated here to  hit the D-D target,

simply gets radiated away to space. This IS an optical system, after all, using optical materials with known properties. 

[Jerome Glenn]

Thanks.

Now exposing my ignorance: Thought some team got controlled fusion for a couple of seconds, several years ago, no? ok, so no proof of net plus energy, but...

Jerry

-----Original Message-----
From: Keith Henson <hkeith...@gmail.com>
Sent: Tuesday, December 13, 2022 1:39 PM
To: a.p.kothari astrox.com <a.p.k...@astrox.com>

[Keith Lofstrom]

On Tue, Dec 13, 2022 at 07:12:51PM +0000, a.p.kothari astrox.com wrote:

> The Q I have is this. Was there a chain reaction here or just fusion of the D-T atoms contained in the pellet? Any opinions?

No chain reaction - a small fraction of events might
have caused other events, but I imagine almost 100% of
the fusion events leaked energy away from the implosion,
not enhancing it. Perhaps scaling radii by a large
number (W.A.G. 100x) might result in gain greater than
one, but that is a million times scaling of input energy.
The New York Times news article described a laser facility
as big as a football stadium (perhaps they meant "field");
a million football field laser is a wee bit spendy.

Mostly, I write to point out that DD fusion is more than
three orders of magnitude more difficult than DT - the
peak reaction rate "cross section" is 30 times smaller for
DD compared to DT ( 1.5e-29m² for DD vs 4e-28m²for DT).
The necessary input energy at those peaks is 20 times
higher ( 2000 KeV for DD versus 100 Kev for DT ). Since
these energies are the tails of a Maxwellian thermal
distribution, they are exponentially harder to achieve.

graph here:
https://www.researchgate.net/figure/Fusion-reaction-cross-sections-for-D-D-of-D-T-reactions_fig1_228365527

I was enamored of fusion half a century ago, and still
have a shelf of technical/research books about it. My
take-away was that nature requires an object the size
of a star to make fusion, and the energy output in the
hottest densest part of that gynormous object is less
than cooling bathwater, per cubic meter of starstuff.

Devices like the Livermore laser won't help us power
the world, but they will teach us how to make more
efficient fission/fusion weapons, destroying our world.
D-T fusion; the tritium is sourced from fission reactors.

(note: an H bomb is a two-focus elliptical mirror,
reflecting energy from a fission detonation at one focus
to deuterium/tritium at the other focus. Difficult to
instrument, measure, and optimize - the Livermore laser
provides valuable empirical data about the first stages
of implosive detonation. Our friend Jordin Kare worked
at Lawrence Livermore, but not in the bomb groups; he
said their motto was "if we don't do our jobs right,
millions of people will ... live").

On the other hand, our Sun blasts out 3.84e26 watts of
light, and our tiny little planet intercepts less than
half a part per billion of the Sun's light output. For
comparison, a single period at the end of a sentence in
my Cokesbury edition Christian Bible is 5 parts per
billion of the total surface of nearly 2000 pages.

In the far future, intelligence will write a vastly more
interesting story than one tenth of a period on the "pages"
of the solar system. The power plant is already running,
and will continue doing so for more than 5 billion years,
while the "fraction of a period" that we live on now will
"soon" be toasted as the Sun heats and expands, unless we
move the Earth further out (yet another email).

If we take a fresh look at the technological landscape
54 years after Peter Glaser's idea, we can refocus our
efforts productively, achieving 100x the profits in
10% of the time with 1% of the effort.

Refocus leads to an information-based "insurmountable
opportunity", a rant that I've written but omitted
from this TL-DR attention-span-stretching email.

Otherwise, if you always do what you've always done,
you always get what you've always got.

Keith L.

--
Keith Lofstrom kei...@keithl.com

[John K. Strickland, Jr.]

Reactions to this announcement seem to range from despair to almost giddy excitement.
The Ignition facility was not built to learn how to produce fusion energy but it did allow some interesting fusion experiments.

The big story is that there are now multiple independent companies trying many different ways to produce fusion energy.
Most are NOT working with the government.
If the government has a goal of a "commercial" fusion system in 10 years, what project lines are they funding to achieve that goal?

The "Breakeven" issue as covered by the media is not very realistic as the total amount of power put into the huge laser to make 1 shot per day is far more than the tiny amount of energy emitted from the target. What we need to look at is the total amount of power used by a plant per unit time vs the amount put out.

The various companies seem to be steadily raising either the temperature, or the pressure or the duration of their plasma or more than one variable.
If this trend continues, it would indicate a possible true fusion breakthrough in a few years.

NOTE that fusion is HIGHLY DESIRABLE for easy access to solar system resources, and to allow both terraforming and interstellar travel via fusion powered "slowboats".

John S

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From: power-satell...@googlegroups.com [mailto:power-satell...@googlegroups.com] On Behalf Of Keith Lofstrom
Sent: Tuesday, December 13, 2022 7:29 PM
To: a.p.kothari astrox.com <a.p.k...@astrox.com>

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[Roger Arnold]

I think your calculations are spot on. 

As to the "chain reaction" part, I guess I was interpolating (aka guessing) as to what I thought you might have taken the term to mean. "Chain reaction" normally applies to fission, when the neutrons released by one fission event directly trigger another one. There's no precisely analogous thing in fusion. Fusion events result from two nuclei colliding with sufficient energy and sufficiently "head on" to cause them to fuse. That's a statistical function of the temperature and pressure within the fireball of the imploded target. At a certain point, the fusion events will be adding energy to the fireball faster than expansion and radiation can drain it. The rising temperature increases the rate at which additional fusion events occur. That's ignition. For a brief moment, the high temperature and pressure within the fireball are sustained by fusion events within the fireball, rather than the external radiation that triggered the implosion. That could be called a chain reaction, and it's what happened in the test that was announced this morning. But there's never a direct link between one fusion event and the next, beyond briefly intensifying the conditions that enable fusion events to occur.

- Roger Arnold

[Paul Werbos]

On Tue, Dec 13, 2022 at 8:34 PM Keith Lofstrom <kei...@kl-ic.com> wrote:

On Tue, Dec 13, 2022 at 07:12:51PM +0000, a.p.kothari astrox.com wrote:

Mostly, I write to point out that DD fusion is more than
three orders of magnitude more difficult than DT - the

This  certainly is well known. Back when people really wanted to sell He3 as a justification for space (It isn't),

I studied reports from the Aneutronic Fusion society, led by Glenn Seaborg, who simply tabulated 

the requirements for D-D, D-T and ... He3... 

BUT Perkins of LLNL certainly knew and accounted for these basics!

That is why design of the fuel pellet targets is such a central issue to all these technologies,

requiring modeling of what happens when light hits any proposed design. The algorithms used in modeling,

the actual physics, and the search of the design space are all essential aspects of being able to make something which works, and then making it work better and better until it is useful.

It is great news they have overcome the first level of challenges, which in some ways were the hardest.

 

[Paul Werbos]

The pellet designs and models make it tricky to characterize what goes on in the pellet, when the light hits it.

It is a MIX of things, for sure. The Perkins D-D pellet designs in the papers in my portable hard drive..

are years old now, but make it clear they were crafting a SEQUENCE of events. The D-D pellets were not pure D-D; there is a kind of catalysis effect, which probably has changed now that they have better models. 

On Wed, Dec 14, 2022 at 2:19 PM James T. Early <james....@protonmail.com> wrote:

There are no chain reactions involved.  A fusion collision between D and T ions produces an alpha ion and a neutron with most of the energy released in the neutron.  The density-radius product of the compressed target  should be large enough that there is one or two collisions between the alpha particles and the ions of D or T.  This will provide enough heating to keep the plasma hot enough to continue the fusion events.   The  neutrons will escape to hit and heat a liquid lithium hydride and steel containment wall surrounding the target area,  A water/lithium hydride heat exchanger produces the hot steam for a conventional electric power generator.

The Livermore program also used to have a 'Mercury" laser program to develop a 10 hertz laser with a 10% electricity to laser conversion efficiency to be used for a plant design.

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[Keith Henson]

On Tue, Dec 13, 2022 at 4:43 PM Paul Werbos <paul....@gmail.com> wrote

>
> On Tue, Dec 13, 2022 at 7:11 PM Keith Henson <hkeith...@gmail.com> wrote:
>>
>> I am still lost. Inertial fusion takes a huge burst of laser energy,
>> in the case of the LL facility, the energy goes from capacitors to
>> flash lamps to laser glass. What is storing the energy in space? I
>> am aware of lasers that are reported to be pumped with sunlight, but
>> this does not give a pulse.
>
> The design included large semiconductor material type disks,
> a typical optical condensed matter structure.

Laser diodes are extremely common, there is one in every Blue-ray or
CD player, but they are tiny. I am still utterly lost as to how this
generates a pulse with no capacitors to store energy.

> Our correspondence and details are on the portable hard drive files, very extensive., and in the Fork/Werbos paper for the OAI conference.

I don't suppose any of this has a URL? I might not understand even a
paper on this topic, but what has been discussed here has left me
completely confused.

> The thermodynamics are based on the generalized Boltzmann probability density operator given in Chaikin's book on Condensed Matter Physics, which the high energy folks seem to miss in scary ways (like when evaluating quantum Information D&T).
>
> The waste energy, which does not contribute to the big optical pulse being generated here to hit the D-D target,
> simply gets radiated away to space. This IS an optical system, after all, using optical materials with known properties.

Unless they are small and low power, the solid-state lasers I know
about require cooling or they get so hot they quit working.

Thermal problems have been the bane of my engineering career.

Keith

[Bruce Pittman]

The most complete study I have seen on laser propulsion is from Charlie Orth from LLNL back in 2000, called VISTA

 

https://www.osti.gov/servlets/purl/15013250

 

They planned on burning DT and throwing away all the neutrons and it weighed 6000 tons.

 

Hopefully, the new technology would make the VISTA concept more attractive.  But just the burn chamber on the NIF weighs 135 tons.

 

But I think Commonwealth Fusion, Helion and TAE have a much better fusion story for space power and propulsion and they have all raised over $1 billion in private funding.  Helion says they can reach breakeven in 2024 and can burn an aneutronic fuel, D-He3 and say they have “demonstrated” plasma to electric energy conversion at 95% efficiency.

 

Bruce

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[John K. Strickland, Jr.]

Note that the Boron-Hydrogen fusion being worked on by TAE is TRULY aneutronic, while the H3e-D fusion is only mostly aneutronic.

One form of Boron Hydrogen fusion propellant can be created by making DiBoron Hydride (B2 H6) , a dense cryogenic liquid easier to store with vastly less volume that Hydrogen or Helium.

 

What would be very useful is the mass breakdown for various propulsion designs for different vehicles, paying close attention to the fuel to dry mass ratio.

For practical interstellar propulsion, you need a similar mass ratio to chemical rockets, since the velocities you need to reach are over 1000 times higher than chemical rocket velocity changes, even though the specific impulse from a working fusion engine should also be over 1000 times higher. This means the dry mass should be less than 2 percent of the wet mass or even less.

Low acceleration rates would allow this with the very low stress on the vehicle’s structure.

 

Fusion powered vehicle will be able to decelerate and come to a STOP in the target star system.

 

John S

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[a.p.kothari astrox.com]

Thanks.

Now… what you have described is how Hydrogen bomb (fusion bomb) works. Was this just a micro fusion bomb then?

 

What we need is Controlled fusion akin to controlled fission with rods and moderators. Some kind of self-feeding mechanism also needs to exist in a controlled manner for the fission reactor to provide continuous energy 365/24/7. Only the initial “spark” is necessary, so to speak. After that the neutron release between 2-3 continues the game, and the control comes from neutron absorption cross-section and insertion of rods in the moderator (water for the PWRs and graphite for TMSR).  

My question is how do they plan to go from this mini-bomb event to a continuous controlled manner, of course WITHOUT the LASERS OPERATING ALL THE TIME? That would be a loser and a non-starter. We cannot have such immense lasers and capacitance to provide a pulse (I think I heard that the total energy required to be stored was equal to what US uses in the same time).

 

The additional pressure and temp increase HAS to continuously come from previous explosions AND HAS TO BE CONTROLLED. It has to be a chain. One can argue whether it is a reaction or fusion event. While the energy release per fusion is 17.6 MeV and U233 fission is 200 MeV (factor of 11 smaller for D-T), the release per unit mass is 3-4 times larger which is a plus.  

 

Don’t get me wrong. What the Shiva/NOVA laser has done is very useful and very impressive. I am just trying to figure out the next step which is ABSOLUTELY NEEDED if we want to apply it for zero CO2 energy for all as it was trumpeted yesterday.

I just want to see a path to that.

 

-Ajay

[Keith Henson]

On Tue, Dec 13, 2022 at 5:34 PM Keith Lofstrom <kei...@kl-ic.com> wrote:

snip

> Mostly, I write to point out that DD fusion is more than
> three orders of magnitude more difficult than DT - the
> peak reaction rate "cross section" is 30 times smaller for
> DD compared to DT ( 1.5e-29m² for DD vs 4e-28m²for DT).
> The necessary input energy at those peaks is 20 times
> higher ( 2000 KeV for DD versus 100 Kev for DT ). Since
> these energies are the tails of a Maxwellian thermal
> distribution, they are exponentially harder to achieve.

I could look it up, but since you seem to have your finger on the
numbers, how hard is the reaction that uses He3?

Keith

[Paul Werbos]

Those are correct calculations if you assume it is designed like a classic fission reactor. It is not.

The fuel pellets are designed to cause a SERIES of steps. Taet makes full sense to you only if

we say what the steps are, raising level of key variables, but not TIHS morning...

[Paul Werbos]

Hi, Keith!

You may have noticed that for many years (POSSIBLY still) the NIF group at LLNL knew this field much better than others, though it has been very strict at times about security.

**IF** my copious folders ever get copied to a stable, open server, it will include many papers from LLNL, especially Perkins, whose work I have cited again and again. It is not a black secret!!! HYes, D-D is harder than D-T, but proper targets have been developed.