Thermonuclear fusion
Ray Drouillard
fusion? Specifically, if I cause ordinary hydrogen (1H) to fuse into
ordinary helium (4He), what are the intermediary steps, what will be
produced (neutrons, beta, gamma?), and how much energy will I get?
When I look at a periodic table, I see that hydrogen has an atomic weight of
1.0079. Is that the average atomic weight of the mixture of hydrogen that
you are likely to find on earth, or is that the actual atomic mass of 1H?
I am asking this because I did some calculations to find out how much energy
it would take to accelerate some alpha and beta particles to 0.5C, and found
it to be very large.
Specifically, to get a kilogram of matter up to half lightspeed, you would
have to convert 1/8 of a kilo of matter to energy and use that with 100%
efficiency to accelerate the kilo of matter.
The results would be a really nice rocket, however. Isp = 15.29 million
seconds :)
Of course, that isn't counting the mass that you are converting to energy.
But, alas, fusion simply doesn't have the "oomph" to do it. OTOH, my story
doesn't really depend on that much performance. If it did (considering how
much time I have spent so far), I would have to handwave some form of zero
point energy or something like that.
Ray Drouillard
mark edward hardwidge
> Where can I find information about the energy yield of various types of
> fusion?
I'm certain there are better resources, but I'm also sure you
could learn a little from this short little document the professor
wrote for the class I TA:
http://www.staff.uiuc.edu/~m-ragheb/NucE302/proton.htm
> When I look at a periodic table, I see that hydrogen has an atomic weight of
> 1.0079. Is that the average atomic weight of the mixture of hydrogen that
> you are likely to find on earth, or is that the actual atomic mass of 1H?
The conventional periodic table lists values for naturally
occuring substances on Earth, not isotropicly pure substances.
If you want to find data on specific isotopes, one good site
is this one at Brookhaven:
http://necs01.dne.bnl.gov/CoN/index.html
--
Mark E. Hardwidge
hard...@uiuc.edu
MA Lloyd
"Ray Drouillard" <droui...@home.com> wrote in message
news:DM0p5.9814$QW4.1...@news1.rdc1.mi.home.com...
> Where can I find information about the energy yield of various types of
> fusion?
There's a FAQ for sci.physics.fusion called the Conventional Fusion FAQ
that lists some of the more commonly discussed types.
> Specifically, if I cause ordinary hydrogen (1H) to fuse into
> ordinary helium (4He), what are the intermediary steps, what will be
> produced (neutrons, beta, gamma?), and how much energy will I get?
There are unfortunately several different cycles for this one, depending
on the catalytic elements present. To the extent they actually go
catalytically they all produce the same net products (two positrons,
two neutrinos and the same amount of energy) but the ratios will
doubtless vary.
> When I look at a periodic table, I see that hydrogen has an atomic weight
of
> 1.0079. Is that the average atomic weight of the mixture of hydrogen that
> you are likely to find on earth, or is that the actual atomic mass of 1H?
The former, periodic table weights are always the average weight for the
terrestrial isotope distribution, since that's what you have in a chemical
reaction. You want a table of isotopes, I'd suggest getting a copy of the
CRC handbook
> But, alas, fusion simply doesn't have the "oomph" to do it.
That's quite correct. Fusion converts less than 1% of the mass involved
to energy, for a maximum exhaust velocity in the neighborhood of .15c
(4.3 million seconds Isp) for converting all the way to iron nuclei, the
energy minimum)
> OTOH, my story
> doesn't really depend on that much performance. If it did (considering
how
> much time I have spent so far), I would have to handwave some form of zero
> point energy or something like that.
Or total conversion. Or antimatter with magic weightless storage
technology.
Or you could always increase the ship's mass ratio. You can in principle
get up to near the speed of light with chemical fuels, provided your mass
ratio is something like 10^25000, with fusion fuels it's down in the range
of a few hundreds to a thousand, which might even be physically possible.
Erik Max Francis
> Where can I find information about the energy yield of various types
> of
> fusion?
I've made a few posts to rec.arts.sf.science detailing the figures, but
I think they've scrolled out of Deja's one year sliding window.
> Specifically, if I cause ordinary hydrogen (1H) to fuse into
> ordinary helium (4He), what are the intermediary steps, what will be
> produced (neutrons, beta, gamma?), and how much energy will I get?
There are two main chains of reactions which stars use to convert H into
He: the proton-proton (p-p) chain and the carbon-nitrogen-oxygen (CNO)
cycle. The reactions are fairly involved and involve subchains and
alternate paths, so they're not really easy to express in ASCII (I'll
try if you like).
Ultimately, though, the sun turns four protons (1H1) into one helium
(4He2) nucleus, which means that ultimately two of those protons must
undergo reverse beta decay (p -> nu + beta^+ + nu), so what you end up
with is
4 1H1 -> 4He2 + 2 beta^+ + 2 nu + (energy).
This (catalyzed) reaction is actually the most energetic fusion reaction
possible (with about 10 times that by any other process!) for total
yield of 6.27 x 10^14 J/kg, or about 0.7% of total conversion. The
neutrinos carry away 2-30% of the total energy, which depends on the
reaction in which they are emitted.
The cross sections of the different reactions are widely varying, and so
there are bottlenecks and stopping blocks in the chains. This is
actually a fairly complicated subject; a good stellar evolution book
will cover it in detail. I'd recommend _Stellar structure and
evolution_ (Kippenhahn and Weigert) or _Principles of stellar evolution
and nucleosynthesis_ (Clayton).
> When I look at a periodic table, I see that hydrogen has an atomic
> weight of
> 1.0079. Is that the average atomic weight of the mixture of hydrogen
> that
> you are likely to find on earth, or is that the actual atomic mass of
> 1H?
The former; the number in periodic tables represents the atomic mass of
that element, adjusted for isotope abundance on Earth. What you want is
an actual table of atomic masses for the different isotopes, which any
reasonably good physics textbook (even undergraduate) should have in the
back, provided it says anything about nuclear reactions. To get you
started, here are enough to get you started:
ISOTOPE ATOMIC MASS
n 1.008 665 u
1H1, p 1.007 825 u
2H1, D 2.014 102 u
3H1, T 3.016 049 u
3He2 3.016 029 u
4He2 4.002 603 u
> I am asking this because I did some calculations to find out how much
> energy
> it would take to accelerate some alpha and beta particles to 0.5C, and
> found
> it to be very large.
>
> Specifically, to get a kilogram of matter up to half lightspeed, you
> would
> have to convert 1/8 of a kilo of matter to energy and use that with
> 100%
> efficiency to accelerate the kilo of matter.
The massic kinetic energy would be about 1 x 10^16 J/kg, so that sounds
about right (more like 1/9 kg, perhaps).
> But, alas, fusion simply doesn't have the "oomph" to do it.
Fusion doesn't do too bad. At 6.3 x 10^14 J/kg you'd expect an ideal
exhaust speed of 3.5 x 10^7 m/s = 0.12 c, which isn't too bad.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
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A new, virtual planet, every day.
Lino P. Stavole
to (almost) absolute zero. B stands for Bose. E for Einstein and C for
condensation
.000 000 0001k
at this very cold state, matter will actually occupy the same space as
another object of matter in a kind of matter soup.
This results from pushing the electrons down to a very low energy level.
Hence condensation. And having subatomic particles of two separate atoms
come close together. I found a wonderful web page after I did a search. But,
that was a while ago and I misplaced the link. This, in theory, would allow
you to transport HUGE amounts of fuel. Much more than 40%. In fact, you also
may get residual energy (I believe in UV radiation) when the electrons warm
and go to there n energy level.
Ray Drouillard
> fusion? Specifically, if I cause ordinary hydrogen (1H) to fuse into
> ordinary helium (4He), what are the intermediary steps, what will be
> produced (neutrons, beta, gamma?), and how much energy will I get?
Thanks Mark, MA, and Erik.
I managed to redesign my fusion drive without ruining the story. The ship
doesn't have the performance of the original, but it is plenty for the story
line. In fact, the fuel tanks are still full of water, and the fuel still
only takes up 40% of the total ship weight.
The main difference is that most trips will involve some coasting. The ship
can run about 2.5 days at one gee, which is plenty for a quick trip to Mars.
Of course, you can fly it to Pluto if you're really patient.
Greater performance can be achieved by storing pure hydrogen fuel in a
liquid, gelled, or slush form (I found a white paper on gelled hydrogen by
typing "liquid hydrogen" into google.com).
Ray Drouillard
Malcolm McMahon
<crea...@famvid.com> wrote:
>B.e.c is the fifth state of matter that is a result of matter being cooled
>to (almost) absolute zero. B stands for Bose. E for Einstein and C for
>condensation
>.000 000 0001k
>at this very cold state, matter will actually occupy the same space as
>another object of matter in a kind of matter soup.
It only works with certain kinds of matter, though. You must have an
integral total spin (typically zero).
amci...@my-deja.com
"Ray Drouillard" <droui...@home.com> wrote:
>
It appears that you're interested in interstellar flight rather than
just fusion. Try reading "The Starflight Handbook" by Mallove and
Matloff.
Sent via Deja.com http://www.deja.com/
Before you buy.
Lino P. Stavole
with all matter?
Erik Max Francis
Because for it to work the collection of particles has to be able to act
as a boson (a particle with integral spin). That's where the name
Bose-Einstein condensate comes from; bosons are so-named because they
are particles which obey Bose-Einstein statistics.
--
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Lino P. Stavole
Erik Max Francis
> so is is true to say b.e.c. is a fifth state of matter?
It's been stated by the popular media. You could call it a new state of
matter, but I don't know how many actual physicists would follow suit.
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Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
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Christopher M. Jones
"Lino P. Stavole" <crea...@famvid.com> wrote:
> so is is true to say b.e.c. is a fifth state of matter?
I suppose you could, but it wouldn't be that useful.
There's all sorts of different "states" of matter that aren't
called "the nth state of matter", but are nevertheless not
really any other state of matter. For example, degenerate
matter, strange matter, "neutronium", super fluidic helium-3,
etc.
Erik Max Francis
> I suppose you could, but it wouldn't be that useful.
>
> There's all sorts of different "states" of matter that aren't
> called "the nth state of matter", but are nevertheless not
> really any other state of matter. For example, degenerate
> matter, strange matter, "neutronium", super fluidic helium-3,
> etc.
Note that for the sake of nitpickery, neutronium is actually a subset of
degenerate matter; it just happened to be neutron-degenerate insted of
electron-degenerate (white dwarf material).
Indeed, your point comes crystal clear, though -- one can certainly name
a bunch of different "states" of matter, but giving them some kind of
official status doesn't make a whole lot of sense, given that there is
overlap and the conditions involve broad ranges of temperature and
pressure.
Other candidate "states of matter" might be superconductors, or liquid
metallic hydrogen, gases/liquids past the critical temperature and
pressure so that there is no longer a distinction, etc.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
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/ \ Music washes away from the soul the dust of everyday life.
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Christopher M. Jones
"Erik Max Francis" <m...@alcyone.com> wrote:
> Note that for the sake of nitpickery, neutronium is actually a subset of
> degenerate matter; it just happened to be neutron-degenerate insted of
> electron-degenerate (white dwarf material).
True, although neutronium does have many properties that
white dwarf material does not have.
> Indeed, your point comes crystal clear, though -- one can certainly name
> a bunch of different "states" of matter, but giving them some kind of
> official status doesn't make a whole lot of sense, given that there is
> overlap and the conditions involve broad ranges of temperature and
> pressure.
>
> Other candidate "states of matter" might be superconductors, or liquid
> metallic hydrogen, gases/liquids past the critical temperature and
> pressure so that there is no longer a distinction, etc.
Quite true. There is another more important reason that you have
hit on here though. The idea of "the 3(+) states of matter", or
solids, liquids, gases, etc. is really only a guideline. Once you
become familiar with the true complexity of matter, you realize
that while the concepts of solids, liquids, and gases are useful,
they are only idealized concepts. In reality, it is very difficult
to find materials that do not in some way violate the precise
definitions of solid, liquid, or gas (or whatever), although gases
tend to more closely "follow the rules". And of course, along the
boundaries, you get a lot of strange things that don't fit into
your 3 little boxes so easily. Things such as very high viscosity
liquids, super-critical gases / liquids (as max mentioned),
nanoparticle emulsions, even very large proteins. Even something
as simple as a mixture of corn starch and water can gray the
line between "states of matter".
It is wise not to take these _guidelines_ of states of matter
too seriously. And, in that light, it would also be wise to
not overly complicate them with additional "oddities of nature".
Erik Max Francis
> True, although neutronium does have many properties that
> white dwarf material does not have.
Sure. It is not the same as electron-degenerate matter, but it _is_
degenerate matter. That was my only point (and I admitted it was
nitpicking -- but helped to emphasize that there are no clear
demarcations).
> It is wise not to take these _guidelines_ of states of matter
> too seriously. And, in that light, it would also be wise to
> not overly complicate them with additional "oddities of nature".
Absolutely. Now, listing a group of oddities of nature, on the other
hand, is perfectly reasonable, and quite interesting, as we've done
here. My long-running favorite is still superfluids.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ No man quite believes in any other man.
\__/ H.L. Mencken
Christopher M. Jones
> hand, is perfectly reasonable, and quite interesting, as we've done
> here. My long-running favorite is still superfluids.
Oooo, that sounds fun.
I'm a bit partial to particle physics oddities myself, things
like glue-balls, quark-gluon plasmas, strange matter, stuff
like that. Although, I also like neutron star matter because
it has so many odd properties (such as (possibly) superfluidity,
superconductivity, and so much more).
Though there's always something to be said for good old
fashioned anti-matter. We've been using it for so long that
in many ways its "oddity" has worn off, but it is still quite
interesting (IMO). I'd like to see someone build an
anti-matter fusion reactor. I'm certain that would be quite
an undertaking (to put it mildly!), but if you could actually
create anti-helium, or anti-carbon, that would just be
absolutely astounding. Now, if you could actually then
proceed to perform "anti-chemistry" (for example, creating
anti-methane, or anti-formaldehyde, or anti-glycine!) that
would just be so amazingly fantabulously jaw-dropping that
your name would probably be remembered for a very very long
time.
Brian Davis
> B.e.c is the fifth state of matter...
Echoing others on parallel subthreads, I'd say it's not. And I know
some of my physics prof's in graduate school hated the term.
> This, in theory, would allow you to transport HUGE amounts of fuel.
> Much more than 40%.
Actually, no. The "40%" that Ray quoted was a perctange of the weight
(read: mass). A Bose-Einstein condensate has the same mass in any state,
so it doesn't change your mass ratio one bit. What it *might* change is
the amount of space you stored the fuel in, but first you've got to find
a useful fuel which can form a b.e.c. in the first place.
--
Brian Davis
Lino P. Stavole
are rich scientist somewhere. If not you deserve to be.
Erik Max Francis
> Hmmm... if an electron going backwards in time is a positron, then
> flipping
> something over in the fourth dimension should create an
> anti-something,
> right?
That would reverse parity. I don't think that parity-reversed electrons
are any different than normal electrons, but I seem to recall that there
are a few particles that have different properties. I seem to recall
something about left-handed vs. right-handed neutrinos, for instance.
I'm not into hardcore particle physics, so I'm sure someone else can
supply some more detail.
--
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/ \ A physicist is an atom's way of knowing about atoms.
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Maths reference / http://www.alcyone.com/max/reference/maths/
A mathematics reference.
Erik Max Francis
> Oooo, that sounds fun.
HONK HONK
> I'm a bit partial to particle physics oddities myself, things
> like glue-balls, quark-gluon plasmas, strange matter, stuff
> like that. Although, I also like neutron star matter because
> it has so many odd properties (such as (possibly) superfluidity,
> superconductivity, and so much more).
Absolutely. It's all good.
> Though there's always something to be said for good old
> fashioned anti-matter. ... Now, if you could actually then
> proceed to perform "anti-chemistry" (for example, creating
> anti-methane, or anti-formaldehyde, or anti-glycine!) that
> would just be so amazingly fantabulously jaw-dropping that
> your name would probably be remembered for a very very long
> time.
I think an actual antihydrogen atom (including a positron) was created
at some point not terribly long ago, which was received with some
fanfare.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
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Ray Drouillard
> in many ways its "oddity" has worn off, but it is still quite
> interesting (IMO). I'd like to see someone build an
> anti-matter fusion reactor. I'm certain that would be quite
> an undertaking (to put it mildly!), but if you could actually
> create anti-helium, or anti-carbon, that would just be
> proceed to perform "anti-chemistry" (for example, creating
> anti-methane, or anti-formaldehyde, or anti-glycine!) that
> would just be so amazingly fantabulously jaw-dropping that
> your name would probably be remembered for a very very long
> time.
Hmmm... if an electron going backwards in time is a positron, then flipping
something over in the fourth dimension should create an anti-something,
right?
Sounds techno-babble enough to confuse the average dabbler :)
Ray Drouillard
Aaron Bergman
<m...@alcyone.com> wrote:
> That would reverse parity. I don't think that parity-reversed electrons
> are any different than normal electrons, but I seem to recall that there
> are a few particles that have different properties. I seem to recall
> something about left-handed vs. right-handed neutrinos, for instance.
The weak force is explicitly parity violating. Electrons come in two
varieties, left handed and right handed, but only the left handed ones
couple to the weak force. The standard model only includes left handed
neutrinos, no right handed ones. This might change, though, as one way
to give the neutrino a (Dirac) mass is to have right handed neutrinos
also. These would probably be sterile neutrinos, however, meaning that
like their electron counterparts, they wouldn't couple to the weak force.
Aaron
--
Aaron Bergman
<http://www.princeton.edu/~abergman/>
Christopher M. Jones
"Erik Max Francis" <m...@alcyone.com> wrote:
> I think an actual antihydrogen atom (including a positron) was created
> at some point not terribly long ago, which was received with some
> fanfare.
Oh yes, several actually, by two different teams / methods if I
remember correctly. They've had little luck in actually getting
them cold enough etc. so they can look at them long enough to
measure some of their properties (an anti-hydrogen emission
spectrum measurement is almost a sure bet for a Nobel, even
more so if it's _not_ the same as "normal" hydrogen).
Erik Max Francis
> The weak force is explicitly parity violating. Electrons come in two
> varieties, left handed and right handed, but only the left handed ones
> couple to the weak force.
Really? I told you I wasn't really up on particle physics.
> The standard model only includes left handed
> neutrinos, no right handed ones.
That's what it was. I remembered something about neutrinos and
chiralty, that was probably it.
> This might change, though, as one way
> to give the neutrino a (Dirac) mass is to have right handed neutrinos
> also. These would probably be sterile neutrinos, however, meaning that
> like their electron counterparts, they wouldn't couple to the weak
> force.
Hmm. What would they couple to, then? (Don't neutrinos interact only
weakly?)
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
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Aaron Bergman
<m...@alcyone.com> wrote:
> Hmm. What would they couple to, then? (Don't neutrinos interact only
> weakly?)
Gravity. That's why they're called sterile.
Christopher M. Jones
"Aaron Bergman" <aber...@princeton.edu> wrote:
> In article <39AB8A2...@alcyone.com>, Erik Max Francis
> <m...@alcyone.com> wrote:
> > Hmm. What would they couple to, then? (Don't neutrinos interact only
> > weakly?)
>
> Gravity. That's why they're called sterile.
Hmmm, and I assume also the "Higgs field".
Aaron Bergman
Jones" <christ...@uswest.net> wrote:
> "Aaron Bergman" <aber...@princeton.edu> wrote:
> > In article <39AB8A2...@alcyone.com>, Erik Max Francis
> > <m...@alcyone.com> wrote:
>
> > > Hmm. What would they couple to, then? (Don't neutrinos interact only
> > > weakly?)
> >
> > Gravity. That's why they're called sterile.
>
> Hmmm, and I assume also the "Higgs field".
If you want to give them a Dirac mass, then they need to be coupled to
the Higgs field. I don't it's necessary if you want to give them a
Majorana mass. Of course, there's not much point to including them, I
think, if you're only going to give them a Majorana mass. It's been a
while since I looked at all this stuff, though.
Erik Max Francis
> Gravity. That's why they're called sterile.
Sounds like you might have a little problem with Occam's razor there --
if they interact only gravitationally, how could you detect them (and be
sure you're not detecting something else)?
--
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Aaron Bergman
<m...@alcyone.com> wrote:
> Aaron Bergman wrote:
>
> > Gravity. That's why they're called sterile.
>
> Sounds like you might have a little problem with Occam's razor there --
> if they interact only gravitationally, how could you detect them (and be
> sure you're not detecting something else)?
Well, you might be able to infer their existence theoretically.
Christopher M. Jones
>
> > Gravity. That's why they're called sterile.
>
> Sounds like you might have a little problem with Occam's razor there --
> if they interact only gravitationally, how could you detect them (and be
> sure you're not detecting something else)?
I assume you wouldn't be able to detect them per se, though
you could infer their presence in experiments (similar to
the way neutrinos were discovered, though probably on a
stronger theoretical footing). You wouldn't really be able
to detect them otherwise, since they won't interract with
anything (other than gravitationally) and they wouldn't
decay into anything else (no weak interraction), quite
intriguing actually.
MA Lloyd
news:39AA82C5...@pdnt.com...
> "Lino P. Stavole" wrote:
> Actually, no. The "40%" that Ray quoted was a perctange of the weight
> (read: mass). A Bose-Einstein condensate has the same mass in any state,
> so it doesn't change your mass ratio one bit. What it *might* change is
> the amount of space you stored the fuel in,
I think it goes up. I haven't followed any of this work much, but I have
the impression that it involves confinement of modest numbers of
atoms in a macroscopic volume, so the densities are substantially less
than typical gases, let alone condensed phases.