What makes the H-bomb so efficient?
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Richard Hester
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Re: What makes the H-bomb so efficient?
Who says it's efficient? A fusion bomb requires a fission bomb to trigger it, and it most likely only fuses a fraction of its fuel before it blows itself to bits. High yield, yes , but efficient? Not necessarily so. It does what it is deigned to do, namely vaporizing a city. When you look at the amount of fuel in one of those bombs and compare the explosion fusion yield against the yield if it were used in a power plant with 40% efficiency, it would most probably be a different story. How far does a 600kT explosion go towardfs fueling a city if you were to stretch out the delivery? An interesting exercise.
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Richard Hester
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Re: What makes the H-bomb so efficient?
In short, the H bomb has the transient high temperature and pressure generated by the X-rays from the fission explosion going for it, and nothing else. The closest one comes to this without a big explosion is the Z-pinch experiment ant Sandia, and this is many orders of magnitude away. The NIF may get there on a small scale if they can ever get the laser to work. This (the H-bomb) is the classic example of the "bigger hammer" taken to absurd extremes.
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Goldenspark
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Re: What makes the H-bomb so efficient?
Did a quick calculation;
New York City, in about 2000, needed about 10GW for peak demand.
1 MT equates to 4.2 x 10^15 J.
This would be enough energy to supply the city for 117 hours (4.86 days) at the peak demand.
And all that from about 50g of mass "expended" (E=MC^2).
New York City, in about 2000, needed about 10GW for peak demand.
1 MT equates to 4.2 x 10^15 J.
This would be enough energy to supply the city for 117 hours (4.86 days) at the peak demand.
And all that from about 50g of mass "expended" (E=MC^2).
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Richard Hull
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Re: What makes the H-bomb so efficient?
The H-bomb question would fall into the category of "Why don't we have nitroglycerin power cars or TNT power electric generators"? There are many small stores in nature of massive amounts of energy. Most are go-no-go reactions that can't be controlled or slowed down. They rely on their very brissant nature to do what they do.
Ya' just can't slow down an H bomb or use any part of its cycle in slow motion mode or it will not work.
Like Richard Hester said. What's efficient about an H bomb? Certainly not its mass-energy conversion ratio which is pitiable. Certainly not the fission part of the bomb either. The seed energy is in the 400 megawatt class to make the hydrogen burn during its several stages (supplied by the fission). That energy has to be applied fast and used fast for the same thing that keeps use from doing slow fusion keeps us from doing it here too. The bastards want to expand to fill the entire universe. The fission and its resultants are speedy enough to get the hydrogen stuff to burn, (fusion) before it is too expanded to do so. speed and brissance are the only reason the thing works at all.
The difference is fission can be easily controlled and scaled back. Fusion cannot, by any method thus far shown, be made to suffer ignition or produce useful energy, though there are many dreams.....Witness the dream of the ITR. or the joke of NIF.
Fission is tough to do due to materials issues, but easy to control. Fusion is easy to do but impossible to make into a usable power source. It is the way nature built things so that the univese would last a long, long time.
We outsmarted nature with fission as it was merely a matter of material concentration over and above that found in nature. Child's play, indeed. Besides, where does nature do fission other than the odd geologically ancient U rock deposit as in Africa? Nature really just doesn't do fission for power. She does it by caprice.
We have not a clue on fusion. The fuel is gulped down in small measure in every cup of coffee, every soft drink we consume and composes a small percentage of over 75 % of our body mass. Fusion fuel is never an issue. Nature has it scattered all about for the burning. Nature does fusion regularly and grossly inefficiently over the enitire universe using only gravity to drive the massive stellar mills of inefficient fusion. Fusion power is nature's engine, not man's. Nature has careful safegaurds in place to prevent small fusion fires being lit and running out of control. Nature has placed us in a position where we are attempting to light matches while submerged in gasoline, relying on an occassional air bubble to get something started. We are far too awash in fusion fuel to light it off except in self limiting flashes.
Richard Hull
Ya' just can't slow down an H bomb or use any part of its cycle in slow motion mode or it will not work.
Like Richard Hester said. What's efficient about an H bomb? Certainly not its mass-energy conversion ratio which is pitiable. Certainly not the fission part of the bomb either. The seed energy is in the 400 megawatt class to make the hydrogen burn during its several stages (supplied by the fission). That energy has to be applied fast and used fast for the same thing that keeps use from doing slow fusion keeps us from doing it here too. The bastards want to expand to fill the entire universe. The fission and its resultants are speedy enough to get the hydrogen stuff to burn, (fusion) before it is too expanded to do so. speed and brissance are the only reason the thing works at all.
The difference is fission can be easily controlled and scaled back. Fusion cannot, by any method thus far shown, be made to suffer ignition or produce useful energy, though there are many dreams.....Witness the dream of the ITR. or the joke of NIF.
Fission is tough to do due to materials issues, but easy to control. Fusion is easy to do but impossible to make into a usable power source. It is the way nature built things so that the univese would last a long, long time.
We outsmarted nature with fission as it was merely a matter of material concentration over and above that found in nature. Child's play, indeed. Besides, where does nature do fission other than the odd geologically ancient U rock deposit as in Africa? Nature really just doesn't do fission for power. She does it by caprice.
We have not a clue on fusion. The fuel is gulped down in small measure in every cup of coffee, every soft drink we consume and composes a small percentage of over 75 % of our body mass. Fusion fuel is never an issue. Nature has it scattered all about for the burning. Nature does fusion regularly and grossly inefficiently over the enitire universe using only gravity to drive the massive stellar mills of inefficient fusion. Fusion power is nature's engine, not man's. Nature has careful safegaurds in place to prevent small fusion fires being lit and running out of control. Nature has placed us in a position where we are attempting to light matches while submerged in gasoline, relying on an occassional air bubble to get something started. We are far too awash in fusion fuel to light it off except in self limiting flashes.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Re: What makes the H-bomb so efficient?
You are correct that H-bombs, especially modern ones, are quite efficient in regards to input/output energies. They work well that way because of the excessively high temperatures (~30 KeV) and pressures (deep in the gigabar range). Since the fusion reaction rate of any fuel at its critical temp is always faster the denser the fuel mass is (I believe that relationship is inverse cubed), the extreme core-of-the-earth type pressure is really important for the H-bomb to work. Early concepts for the H-bomb did not have a compression element in their design, and always proved infeasible on paper because of it irrespective of the temperature theorized.
Unfortunately, for those pressures at those temperatures, the only option for confinement is fast, high energy shock implosion of something already at a pretty high density (a solid or liquid) to begin with. Of course maintaining such an environment isn't really feasible for more than microseconds at best. The only way to do that seems to be to blow up the device in the reaction with ionizing radiation, see NIF (if it works at all), z-pinch, W-88, etc. Any electrostatic or magnetic system designed to continously confine such a plasma at that density and survive, even a gram of it, would be as big as the Superdome at least.
Unfortunately, for those pressures at those temperatures, the only option for confinement is fast, high energy shock implosion of something already at a pretty high density (a solid or liquid) to begin with. Of course maintaining such an environment isn't really feasible for more than microseconds at best. The only way to do that seems to be to blow up the device in the reaction with ionizing radiation, see NIF (if it works at all), z-pinch, W-88, etc. Any electrostatic or magnetic system designed to continously confine such a plasma at that density and survive, even a gram of it, would be as big as the Superdome at least.
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Donald McKinley
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Re: What makes the H-bomb so efficient?
Mike,
If published information on the H-Bomb yields is reliable (it may not be), it is definitely more energetic on a TOTAL MASS BASIS than the fission reactions. However it is not as much more energetic as you might think. It's somewhat less than 4 times as potent.
The 9 Megaton Mk-53/B-53 bomb, which apparantely is the oldest weapon in service (operational since 1962), and also the largest, weighs 4000 kg and has a ratio of 2.25 kt/kg. I believe it is fusion primarily.
This is 4.5 lbs of tnt per mg.
The 100 kt W-76 bomb is a fission only bomb which weighs 165kg has a yield/weight ratio of .061kt/kg.
This is 1.21 lbs tnt per mg.
As you can see, regarding the original question on this thread, on an equal mass basis this fuel is significantly more potent. Its true that each reaction has much less energy, but there are scads more of them. Since many of the reactions involve tritium, an energy density of 4.5 lbs per mg is probably way more potent than pure deuterium would be in a fusor.
There is also a giant fudge factor in the numbers above because the energy content is computed on the entire weight of the bombs including all the inert weight
I did a search for the bomb stats & found them at http://nuclearweaponarchive.org/Nwfaq/N ... #Nfaq4.5.3
Don M.
If published information on the H-Bomb yields is reliable (it may not be), it is definitely more energetic on a TOTAL MASS BASIS than the fission reactions. However it is not as much more energetic as you might think. It's somewhat less than 4 times as potent.
The 9 Megaton Mk-53/B-53 bomb, which apparantely is the oldest weapon in service (operational since 1962), and also the largest, weighs 4000 kg and has a ratio of 2.25 kt/kg. I believe it is fusion primarily.
This is 4.5 lbs of tnt per mg.
The 100 kt W-76 bomb is a fission only bomb which weighs 165kg has a yield/weight ratio of .061kt/kg.
This is 1.21 lbs tnt per mg.
As you can see, regarding the original question on this thread, on an equal mass basis this fuel is significantly more potent. Its true that each reaction has much less energy, but there are scads more of them. Since many of the reactions involve tritium, an energy density of 4.5 lbs per mg is probably way more potent than pure deuterium would be in a fusor.
There is also a giant fudge factor in the numbers above because the energy content is computed on the entire weight of the bombs including all the inert weight
I did a search for the bomb stats & found them at http://nuclearweaponarchive.org/Nwfaq/N ... #Nfaq4.5.3
Don M.
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Alex Aitken
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Re: What makes the H-bomb so efficient?
Its interesting that high temperatures are mentioned, as its my understanding this is a problem, rather than an advantage in the early stages of fuel compression.
My understanding is that if you take a high temperature plasma allready fusing and squash it, the fusion rate will rapidly increase until it balences the force you apply. Not unlike the way fusion in the sun constantly balences force due to gravity. When that force is then removed fusion rate drops rapidly and you've just fizzled, if equal force requires equal energy then you can only double the energy production in the bomb as a rough number (based on a bad estimate). If you can squash the fusile material while cold though you can achieve much higher densities as you arn't fighting fusion. Then when the plutonium 'sparkplug' also being compressed finally detonates (as a secondary fast fission bomb in its own right, aside from the primary that is doing compression) fusion starts with this much higher density and the temperature spikes much more rapidly and uses far more of the fuel. Its almost a perfect analog of the plutonium predetonation problem in pure fission weapons.
With regard to TNT or nitroglycerine powered cars the reason is actually different. With a H Bomb there is no question that it achieves more energy than available by other means as well as short term power. With nitroglycerine/TNT this is simply not true. The tradeoff for making a molecule that releases its energy in such a small amount of time (less than a microsecond, most of the time in a half a millisecond ish detonation is just wating to be hit by the det wave) is that the total energy released is less per unit mass than most fuels. A kilogram of TNT or Niroglycerine when detonated actually release Much less energy than a kilogram of gasoline. The two key reasons for this are that detonating explosives have to carry the oxidiser as well as the fuel in the mass (cf difference between a rocket and a jet engine), and that intramolecular redox reactions of chemicals stable enough to be handled produce less energy than intermolecular redox reactions (cf the difference between single molecule explosives like TNT and versions with aluminium or silicon powder and oxidisers or even just straight low order propellents).
My understanding is that if you take a high temperature plasma allready fusing and squash it, the fusion rate will rapidly increase until it balences the force you apply. Not unlike the way fusion in the sun constantly balences force due to gravity. When that force is then removed fusion rate drops rapidly and you've just fizzled, if equal force requires equal energy then you can only double the energy production in the bomb as a rough number (based on a bad estimate). If you can squash the fusile material while cold though you can achieve much higher densities as you arn't fighting fusion. Then when the plutonium 'sparkplug' also being compressed finally detonates (as a secondary fast fission bomb in its own right, aside from the primary that is doing compression) fusion starts with this much higher density and the temperature spikes much more rapidly and uses far more of the fuel. Its almost a perfect analog of the plutonium predetonation problem in pure fission weapons.
With regard to TNT or nitroglycerine powered cars the reason is actually different. With a H Bomb there is no question that it achieves more energy than available by other means as well as short term power. With nitroglycerine/TNT this is simply not true. The tradeoff for making a molecule that releases its energy in such a small amount of time (less than a microsecond, most of the time in a half a millisecond ish detonation is just wating to be hit by the det wave) is that the total energy released is less per unit mass than most fuels. A kilogram of TNT or Niroglycerine when detonated actually release Much less energy than a kilogram of gasoline. The two key reasons for this are that detonating explosives have to carry the oxidiser as well as the fuel in the mass (cf difference between a rocket and a jet engine), and that intramolecular redox reactions of chemicals stable enough to be handled produce less energy than intermolecular redox reactions (cf the difference between single molecule explosives like TNT and versions with aluminium or silicon powder and oxidisers or even just straight low order propellents).
Re: What makes the H-bomb so efficient? A: (with no math)
Sorry it took this long but I am trying to make this a simple as
possible.
When you look at overall fusion efficiency there are 4 aspects:
1: Energy per reaction.
2: Average energy input per fuel molecule.
3: Percentage of fuel undergoing reaction.
4: What percentage of output energy is useful.
Now H-Bombs maximize #1 by using D-T reactions AND using the
neutrons as a fission “catalyst”. (These are both vary “dirty” methods
in that they produce a lot of high-energy neutrons, but hey it’s a
bomb.)
Now #2 uses a cool trick in that they use a bomb to get into the
30+kev range but as these things take place at such a high pressure
the mean free path is vary low thus they get to use the “free” energy
from the early fusion reactions to increase the plasma temperature for
the later reactions. Also they get to compress things to extreme
levels before hitting the insane temperature levels which would rapidly
produce too much pressure to allow for compression.
Now #3 is a function of both containment time and plasma
temperature AND plasma density. Containment time sucks for an H-
Bomb but plasma temperature gets into the Mev range and pressure
goes though the roof which causes the density to quickly drop as
containment fails but the mean free path is so low that you get a lot of
reactions even as the thing is detonating. Basically if you have a 6cm
ball at 30kev that becomes a 12cm ball at 300kev the larger ball is still
going to undergo some fusion. You also get a little fusion as the high-
energy fusion materials encounter atmospheric hydrogen.
Finally H-Bomb’s don’t waste any of the input energy so even a 60%
efficient H-Bomb is still useful. Basically a 1MT bomb that becomes
a 1.6MT bomb is much better where a power plant needs to be
~300% power input to break even. It’s my understanding that early
H-Bomb’s got little of there energy from fusion but focused on fission
+ some fusion + fusion catalyzed fission = bigger bomb.
Continuing the basic idea. If you wanted to build an insanely big H-
Bomb you could surround a super cooled high (extreme density) ball
with normal H-Bomb’s to drive up the density and hit 30+ Kev igniting
a huge ball for a (relatively) long period of time. Even if the central
ball only produced 50% of the energy of the containment H-Bomb’s
your new (mega) H-Bomb is now as powerful as say 6 H-Bomb’s
while being slightly larger than 4 normal H-Bombs. You would have
serious issues trying to time the 4+ H-Bomb’s to get this to work but
it’s still doable. (I don’t know why you would need a bomb that size
but it gives you an idea of the basic premise behind H-bombs.)
PS: Or on a more basic level when building an H-bomb you get to
work with insane energy levels and don’t have to worry about
containment losses so it’s easy to set thing on fire.
possible.
When you look at overall fusion efficiency there are 4 aspects:
1: Energy per reaction.
2: Average energy input per fuel molecule.
3: Percentage of fuel undergoing reaction.
4: What percentage of output energy is useful.
Now H-Bombs maximize #1 by using D-T reactions AND using the
neutrons as a fission “catalyst”. (These are both vary “dirty” methods
in that they produce a lot of high-energy neutrons, but hey it’s a
bomb.)
Now #2 uses a cool trick in that they use a bomb to get into the
30+kev range but as these things take place at such a high pressure
the mean free path is vary low thus they get to use the “free” energy
from the early fusion reactions to increase the plasma temperature for
the later reactions. Also they get to compress things to extreme
levels before hitting the insane temperature levels which would rapidly
produce too much pressure to allow for compression.
Now #3 is a function of both containment time and plasma
temperature AND plasma density. Containment time sucks for an H-
Bomb but plasma temperature gets into the Mev range and pressure
goes though the roof which causes the density to quickly drop as
containment fails but the mean free path is so low that you get a lot of
reactions even as the thing is detonating. Basically if you have a 6cm
ball at 30kev that becomes a 12cm ball at 300kev the larger ball is still
going to undergo some fusion. You also get a little fusion as the high-
energy fusion materials encounter atmospheric hydrogen.
Finally H-Bomb’s don’t waste any of the input energy so even a 60%
efficient H-Bomb is still useful. Basically a 1MT bomb that becomes
a 1.6MT bomb is much better where a power plant needs to be
~300% power input to break even. It’s my understanding that early
H-Bomb’s got little of there energy from fusion but focused on fission
+ some fusion + fusion catalyzed fission = bigger bomb.
Continuing the basic idea. If you wanted to build an insanely big H-
Bomb you could surround a super cooled high (extreme density) ball
with normal H-Bomb’s to drive up the density and hit 30+ Kev igniting
a huge ball for a (relatively) long period of time. Even if the central
ball only produced 50% of the energy of the containment H-Bomb’s
your new (mega) H-Bomb is now as powerful as say 6 H-Bomb’s
while being slightly larger than 4 normal H-Bombs. You would have
serious issues trying to time the 4+ H-Bomb’s to get this to work but
it’s still doable. (I don’t know why you would need a bomb that size
but it gives you an idea of the basic premise behind H-bombs.)
PS: Or on a more basic level when building an H-bomb you get to
work with insane energy levels and don’t have to worry about
containment losses so it’s easy to set thing on fire.
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Donald McKinley
- Posts: 185
- Joined: Tue Nov 01, 2005 10:53 pm
- Real name: Donald McKinley
Re: What makes the H-bomb so efficient? A: (with no math)
JKirby,
greetings
Could you amplify a little teeny tiny bit on the 30--300Kev issues, as well as the 3rd to last paragraph regarding the
"power plant needs to be ~300% power input to break even".
I know its been sort of covered, but I'm still on the uptick here. Don't quite have the whole process under control.
I'm interested, if possible, on any known sweet spots in the process where voltages to pressures () may be ideal. So far I've gleaned perhaps wrongly that there is a large factor of "more is better".
I'm slowly working my way through the "Fundamental Plasma Limitations etc." Phd Thesis of Tod Rider recommended by Brian M. It'll be awhile.
Thanks
Don
greetings
Could you amplify a little teeny tiny bit on the 30--300Kev issues, as well as the 3rd to last paragraph regarding the
"power plant needs to be ~300% power input to break even".
I know its been sort of covered, but I'm still on the uptick here. Don't quite have the whole process under control.
I'm interested, if possible, on any known sweet spots in the process where voltages to pressures () may be ideal. So far I've gleaned perhaps wrongly that there is a large factor of "more is better".
I'm slowly working my way through the "Fundamental Plasma Limitations etc." Phd Thesis of Tod Rider recommended by Brian M. It'll be awhile.
Thanks
Don
Re: What makes the H-bomb so efficient? A: (with some math)
However, this is an outline of what’s going on so I am not going to be
overly technical but you can’t really compare things without a little
math.
"power plant needs to be ~300% power input to break even".
Let’s start with http://www.sciencemag.org/cgi/content/summary/278/
5335/29a where “JET produced 50% of the energy supplied to the
reactor--close to twice the previous record.” Ok well energy can’t be
created or destroyed so what are they talking about? Well for a few
seconds JET can liberate some atomic energy as heat, but it takes a
constant supply of electrical energy to do so. So if you started with
100kw/s of electricity you get 150kw/s of heat which better than a
space heater. However, if you want to turn that heat back to
electricity you lose about 60% of the energy. So that 150kw of heat is
only 60kw/s of electricity which is less than we started with. If you
want to get twice as much electricity out as you put in you need a
power plant that adds 4kw of heat per 1kw of electricity you add.
(4kw+1kw)(Energy) 40%(efficiency) = 2kw of electricity.
As to the 300% isue: (2kw + 1kw) * .4 = 1.2kw out per 1kw in which
is probably not really useful, it could start to be useful at that level, but
I pick 300% output (from fusion) to input as a true breakeven. After
that more becomes more useful but that’s about where the threshold
starts.
However, let’s take a 1MT A-Bomb that produces 1MT worth of heat
energy. Now if you take all that heat(not really possible) and use it to
drive a 50% efficient reactor you get 1.5MT of heat but as your talking
about a bomb you get to use all that heat to blow things up. (Not all of
that energy starts out as heat you get things like x-ray’s ect but it all
quickly becomes heat). Now in the real world you might only get 5%
of the A-Bomb’s heat to drive fusion but the fusion is going to be way
more than 50% efficient.
Now onto the 30>300KV issues:
If they took the basic jet design and rebuilt the same device they
would be stuck with the same performance. However, they are
scaling up the same basic design. ITER is not really going to be much
hotter or have much higher dencity than JET but it’s going to be a lot
larger. http://www.jet.efda.org/pages/content/tokamak-
description.html Vs. http://www.iter.org/plasma.htm (from http://
www.iter.org/index.htm)
Now in fusion each of the ion’s is going about 1000+ miles per
second (3,600,000mph) but the ITER plasma is only ~6m wide which
mean they need to use a strong magnetic field to contain the plasma.
Which is all well and good but it has limits after fusion you get a
neutron with 14,100kev of energy that ignores the magnetic field and
a 3,500kev Helium nucleus, which is going way to fast to be stopped
by that field. Now as the size or density goes up you increase the
chances of those particles hitting some deuterium or tritium which
would increase the overall plasma temperature but you have the
same problem, the magnetic filed is not strong enough to contain a
higher temperature particle so you hit a limit as to how hot things can
get.
But let’s take another approach instead of having a huge ring of low
density plasma let’s have a small ball 1cm wide with 1,000 times that
much plasma. First off the chances of helium or neutron hitting some
deuterium or tritium are now much higher. So after things start to fuse
the plasma temperature is going to rise. 60kev in gives ~17,600 + 60
kev out, but now the 1cm wide ball is going to start blowing up at a
good chunk of the speed of light so things need to happen fast.
Luckily as the temperature rise the probability of fusion goes up
dramatically and the density is way higher than ITER so in that tiny
fraction of a second before things are blown up you get an insane
amount of fusion.
More temperature, and or more volume, and or more density yield
more fusion. There is no sweet spot it’s just a question of how large,
how hot, and how well contained plasma you can create. In a bomb
you basically give up on containment time and try to maximize the
temperature, density, and volume.
PS: Density is more valuable than volume if you can pack the same
number of ions into a smaller space you get much more fusion.
overly technical but you can’t really compare things without a little
math.
"power plant needs to be ~300% power input to break even".
Let’s start with http://www.sciencemag.org/cgi/content/summary/278/
5335/29a where “JET produced 50% of the energy supplied to the
reactor--close to twice the previous record.” Ok well energy can’t be
created or destroyed so what are they talking about? Well for a few
seconds JET can liberate some atomic energy as heat, but it takes a
constant supply of electrical energy to do so. So if you started with
100kw/s of electricity you get 150kw/s of heat which better than a
space heater. However, if you want to turn that heat back to
electricity you lose about 60% of the energy. So that 150kw of heat is
only 60kw/s of electricity which is less than we started with. If you
want to get twice as much electricity out as you put in you need a
power plant that adds 4kw of heat per 1kw of electricity you add.
(4kw+1kw)(Energy) 40%(efficiency) = 2kw of electricity.
As to the 300% isue: (2kw + 1kw) * .4 = 1.2kw out per 1kw in which
is probably not really useful, it could start to be useful at that level, but
I pick 300% output (from fusion) to input as a true breakeven. After
that more becomes more useful but that’s about where the threshold
starts.
However, let’s take a 1MT A-Bomb that produces 1MT worth of heat
energy. Now if you take all that heat(not really possible) and use it to
drive a 50% efficient reactor you get 1.5MT of heat but as your talking
about a bomb you get to use all that heat to blow things up. (Not all of
that energy starts out as heat you get things like x-ray’s ect but it all
quickly becomes heat). Now in the real world you might only get 5%
of the A-Bomb’s heat to drive fusion but the fusion is going to be way
more than 50% efficient.
Now onto the 30>300KV issues:
If they took the basic jet design and rebuilt the same device they
would be stuck with the same performance. However, they are
scaling up the same basic design. ITER is not really going to be much
hotter or have much higher dencity than JET but it’s going to be a lot
larger. http://www.jet.efda.org/pages/content/tokamak-
description.html Vs. http://www.iter.org/plasma.htm (from http://
www.iter.org/index.htm)
Now in fusion each of the ion’s is going about 1000+ miles per
second (3,600,000mph) but the ITER plasma is only ~6m wide which
mean they need to use a strong magnetic field to contain the plasma.
Which is all well and good but it has limits after fusion you get a
neutron with 14,100kev of energy that ignores the magnetic field and
a 3,500kev Helium nucleus, which is going way to fast to be stopped
by that field. Now as the size or density goes up you increase the
chances of those particles hitting some deuterium or tritium which
would increase the overall plasma temperature but you have the
same problem, the magnetic filed is not strong enough to contain a
higher temperature particle so you hit a limit as to how hot things can
get.
But let’s take another approach instead of having a huge ring of low
density plasma let’s have a small ball 1cm wide with 1,000 times that
much plasma. First off the chances of helium or neutron hitting some
deuterium or tritium are now much higher. So after things start to fuse
the plasma temperature is going to rise. 60kev in gives ~17,600 + 60
kev out, but now the 1cm wide ball is going to start blowing up at a
good chunk of the speed of light so things need to happen fast.
Luckily as the temperature rise the probability of fusion goes up
dramatically and the density is way higher than ITER so in that tiny
fraction of a second before things are blown up you get an insane
amount of fusion.
More temperature, and or more volume, and or more density yield
more fusion. There is no sweet spot it’s just a question of how large,
how hot, and how well contained plasma you can create. In a bomb
you basically give up on containment time and try to maximize the
temperature, density, and volume.
PS: Density is more valuable than volume if you can pack the same
number of ions into a smaller space you get much more fusion.
Re: What makes the H-bomb so efficient? A: (with some math)
Hi folks:
Without going into too much detail which I've done in other posts.
Simply remember a H-Bomb only fuses 2% or maybe at best 10% of the fuel load the rest turns into fallout. The longest time of thermonuclear burn is measured in microseconds.
Using an H-Bomb as a heat source would be like using 20 billion dollars in crisp 100 dollar bills as fuel for a wood furnace.
If it worked would you be at this forum? I don't think so!
Happy Fusoring!
Larry Leins
Fusor Tech
Without going into too much detail which I've done in other posts.
Simply remember a H-Bomb only fuses 2% or maybe at best 10% of the fuel load the rest turns into fallout. The longest time of thermonuclear burn is measured in microseconds.
Using an H-Bomb as a heat source would be like using 20 billion dollars in crisp 100 dollar bills as fuel for a wood furnace.
If it worked would you be at this forum? I don't think so!
Happy Fusoring!
Larry Leins
Fusor Tech
Re: What makes the H-bomb so efficient? A: (with some math)
Steam type power plants operate typically in the 30-45% thermal efficiency range. Using 33% efficiency as the "easy math" figure, then the plant consumes 3 times as much fuel energy as the electrical energy it produces.
Therefore if the assumed fusion-thermal process operated successfully at the temperatures of a typical supercritical boiler approximately with 1050 F (566 C) superheat (which may be too hot for a high voltage process) , then it would take 3 KWhr of heat energy to produce 1 KWhr of electricity, and etc.
Thus you need a fusion output of some 300% of the desired electrical output.
If you were getting some of the energy directly from charged particle deceleration, the efficiency for that portion of the process could approach 100% without violating any thermodynamic principles.
Dave Cooper
Therefore if the assumed fusion-thermal process operated successfully at the temperatures of a typical supercritical boiler approximately with 1050 F (566 C) superheat (which may be too hot for a high voltage process) , then it would take 3 KWhr of heat energy to produce 1 KWhr of electricity, and etc.
Thus you need a fusion output of some 300% of the desired electrical output.
If you were getting some of the energy directly from charged particle deceleration, the efficiency for that portion of the process could approach 100% without violating any thermodynamic principles.
Dave Cooper
-
Richard Hull
- Moderator
- Posts: 15034
- Joined: Fri Jun 15, 2001 9:44 am
- Real name: Richard Hull
Re: What makes the H-bomb so efficient? A: (with some math)
This all goes back to satisfying the bean counters and the engineers in the REAL WORLD power biz.
Everyone who really believes that JET or any fusion reactor has produced 50kw more energy out that was put in please raise your hand!!
Fusion doesn't stand a chance by any measure of the current planning on ITER or JET or whatever! So, the upshot is now that with steam, 300% out of a fusion system IS BREAKEVEN!
Thus, you might say that until you hit about 1000% the fusion power system would not interest a real "going concern" in the power biz to swing through its current infrastructure to create new.
It is important to remember the current "longest run" times (fractions of a minute) of the finest fusion efforts, all at under unity and compare that with say, some of the many late 1960's fission reactors that have never stopped producing multi-megawatts, 24-7-365 for the last 40 odd years. We aren't even at the distant vision point with fusion yet, by any methodology.
ITER is just the next carefully planned and executed mistep in a long running fusion boon-doggle.
Richard Hull
Everyone who really believes that JET or any fusion reactor has produced 50kw more energy out that was put in please raise your hand!!
Fusion doesn't stand a chance by any measure of the current planning on ITER or JET or whatever! So, the upshot is now that with steam, 300% out of a fusion system IS BREAKEVEN!
Thus, you might say that until you hit about 1000% the fusion power system would not interest a real "going concern" in the power biz to swing through its current infrastructure to create new.
It is important to remember the current "longest run" times (fractions of a minute) of the finest fusion efforts, all at under unity and compare that with say, some of the many late 1960's fission reactors that have never stopped producing multi-megawatts, 24-7-365 for the last 40 odd years. We aren't even at the distant vision point with fusion yet, by any methodology.
ITER is just the next carefully planned and executed mistep in a long running fusion boon-doggle.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Re: What makes the H-bomb so efficient? A: (with some math)
I think we have had this discussion a few times. But, to clarify I never
said that JET produced 50kw more energy out than was put in. I was
trying to use simple numbers to explain what efficiency meant for
electricity generation. We can pick an arbitrary “breakeven” and
useful numbers but adoption is going to be the real test of success. If
we want real numbers: at it’s best Jet gave us:
22 MJ of fusion energy in one pulse
16 MW of peak fusion power
A 65% ratio of fusion power produced to total input power.
http://www.jet.efda.org/pages/history-of-jet.html
As it’s only producing 16 MW of power over short periods of time
there is zero electricity recovery going on. However, the fusion
power ratio means that for an input of ~25MW of electricity you get
~16MW of heat from fusion AND ~25MW of heat directly from
electricity AND some heat from fission (all those neutrons activate
stuff some of which decays).
At this point we need to go to theory. (Which Mr. Hull seems to hate.
Where / are you an engineer?)
Anyway, from a TD perspective fusion operates at an extreme
temperature and can give you insane efficiency levels, but working
with proven systems we can reasonably assume 40% efficiency.
Now assuming the fission heat counters the heat that is lost and not
directly used in our power plant we have (16 + 25) MW * .4 = the
potential to generate ~16.4 MW of electricity. Which just happens to
be the same efficiency as the ratio of fusion power produced to input
power, but that’s simply an odd outcome based on the 65% fusion
power level and would not show up under any other efficiency level.
Solving (X+1)* .4 = 1 for X gives us 1.5 so “breakeven” is 150% if the
input power is also converted to heat, which is true. Solving X *.4 = 1
for X gives us 2.5 or 250%, so if we ignore the heat generated by
electricity (which is stupid IMO). Now in the real world power plants
could as high as 45% AND you can use low-grade heat for other
processes. (I like the idea of heating northern city’s via underground
pipes to get rid of winter snow and ice and eliminate heating costs,
but that gets into insane power requirements. 1GW would keep
~1km^2 clear but you would probably create a huge updraft...)
Anyway, cheep heat for local chemical plants or homes seems like
the best use of such energy.
Moving back to the real world there are significant power
requirements to process tritium and other losses associated with
basic plant upkeep, which alter the picture somewhat.
Anyway, moving back into theory. Jet and other Tokamak designs
are limited in efficiency based on their size. The math is complex but
if you double the size of the facility you more than double efficiency.
There are several breakeven points but a large enough Tokamak
needs no input energy to sustain fusion temperatures other than the
minimal losses associated with cooling the coils.
In 15-20 years we can look at ITER and see things work out, but the
basic math says that the larger you build the system the easer they
are. At this point the largest problem is probably getting a sufficient
supply of tritium, but a lithium blanket seems like a reasonable
solution to that problem. Jet produces 22 MJ of energy from less
than .05 grams of tritium so assuming a reasonable operating
efficiency most of the other problems are probably solvable.
PS: JET operated for up to 60 seconds at a time an ITER should
operate for over 1000 seconds (16min 40 sec) at a time. Once again
scaling the system produces vast improvements in operating
conditions.
said that JET produced 50kw more energy out than was put in. I was
trying to use simple numbers to explain what efficiency meant for
electricity generation. We can pick an arbitrary “breakeven” and
useful numbers but adoption is going to be the real test of success. If
we want real numbers: at it’s best Jet gave us:
22 MJ of fusion energy in one pulse
16 MW of peak fusion power
A 65% ratio of fusion power produced to total input power.
http://www.jet.efda.org/pages/history-of-jet.html
As it’s only producing 16 MW of power over short periods of time
there is zero electricity recovery going on. However, the fusion
power ratio means that for an input of ~25MW of electricity you get
~16MW of heat from fusion AND ~25MW of heat directly from
electricity AND some heat from fission (all those neutrons activate
stuff some of which decays).
At this point we need to go to theory. (Which Mr. Hull seems to hate.
Where / are you an engineer?)
Anyway, from a TD perspective fusion operates at an extreme
temperature and can give you insane efficiency levels, but working
with proven systems we can reasonably assume 40% efficiency.
Now assuming the fission heat counters the heat that is lost and not
directly used in our power plant we have (16 + 25) MW * .4 = the
potential to generate ~16.4 MW of electricity. Which just happens to
be the same efficiency as the ratio of fusion power produced to input
power, but that’s simply an odd outcome based on the 65% fusion
power level and would not show up under any other efficiency level.
Solving (X+1)* .4 = 1 for X gives us 1.5 so “breakeven” is 150% if the
input power is also converted to heat, which is true. Solving X *.4 = 1
for X gives us 2.5 or 250%, so if we ignore the heat generated by
electricity (which is stupid IMO). Now in the real world power plants
could as high as 45% AND you can use low-grade heat for other
processes. (I like the idea of heating northern city’s via underground
pipes to get rid of winter snow and ice and eliminate heating costs,
but that gets into insane power requirements. 1GW would keep
~1km^2 clear but you would probably create a huge updraft...)
Anyway, cheep heat for local chemical plants or homes seems like
the best use of such energy.
Moving back to the real world there are significant power
requirements to process tritium and other losses associated with
basic plant upkeep, which alter the picture somewhat.
Anyway, moving back into theory. Jet and other Tokamak designs
are limited in efficiency based on their size. The math is complex but
if you double the size of the facility you more than double efficiency.
There are several breakeven points but a large enough Tokamak
needs no input energy to sustain fusion temperatures other than the
minimal losses associated with cooling the coils.
In 15-20 years we can look at ITER and see things work out, but the
basic math says that the larger you build the system the easer they
are. At this point the largest problem is probably getting a sufficient
supply of tritium, but a lithium blanket seems like a reasonable
solution to that problem. Jet produces 22 MJ of energy from less
than .05 grams of tritium so assuming a reasonable operating
efficiency most of the other problems are probably solvable.
PS: JET operated for up to 60 seconds at a time an ITER should
operate for over 1000 seconds (16min 40 sec) at a time. Once again
scaling the system produces vast improvements in operating
conditions.
Re: What makes the H-bomb so efficient? A: (with some math)
We need to keep our heads above water, doing these "theory" excursions in Thermodynamics.
First - very high temperatures, do NOT produce "insane" efficiencies... they only allow Carnot efficiencies to approach 100%. And "all" it takes to get to a theoretical 99% efficiency figure is a high temperature for absorbing the energy of about 100 times the low temperature heat rejection temperature.
If you are working with a heat rejection apparatus (aka heat exchanger) ...at say 127 C or 400K, then the high temperature part of the system is a measly 40,000 K... about 3.5 eV. Piece of cake. eh?
Except for the fact that all known materials are in plasma form at these temperatures and thus the apparatus for extracting this energy has to be able to work with plasmas.
That said, we are not any closer than before to having anything we yet know how to build work at these temperatures or at this efficiency.
Also, I am sensing that there tends to be either a bit of indifference or inadvertency in the mixing of energy and power in discussing Fusion device outputs. With pulse type devices, this is a very common problem. Failing to properly integrate the input energy over the device's entire cycle, leds often to outragious and physically impossible claims of efficiencies... i.e.: > 100%.
I think all on this net are more or less aware of these pitfalls, so there's no need to preach on this subject.
Where there is a need to remain alert, is when we are adding up thermal energy..."heat".... without regard to temperature. Here you can get a real headache... because it is entirely possible to move more low grade heat than you put into something... because along the way in the process, mechanical work, electrical energy, mass, etc.... was converted into low grade heat. The heat pump is the obvious example... moving more heat than the equivalent elecrical or fuel energy that was in put.
The amount of work that a low temperature device can do.. approaches zero, as the high temperature of the device approaches the temperature at which heat is to be rejected.
The amount of heat that such a device can pass, while doing almost zero work... increases without limit, as the high temperature approaches the low temperature limit.
So... where all we need is heat, we should use devices that pass through.. heat. Where we need work, we have to worry about how "hot" (temperature) the heat is, and hence the Carnot efficiency.
But we need to always remember the Carnot efficiency is the theoretical limiting efficiency... the bogey... not the achievable day in -day out practical operating efficiency... We do well usually to approach 75% of Carnot efficiency with most devices.
Hope this is useful..
Dave Cooper
First - very high temperatures, do NOT produce "insane" efficiencies... they only allow Carnot efficiencies to approach 100%. And "all" it takes to get to a theoretical 99% efficiency figure is a high temperature for absorbing the energy of about 100 times the low temperature heat rejection temperature.
If you are working with a heat rejection apparatus (aka heat exchanger) ...at say 127 C or 400K, then the high temperature part of the system is a measly 40,000 K... about 3.5 eV. Piece of cake. eh?
Except for the fact that all known materials are in plasma form at these temperatures and thus the apparatus for extracting this energy has to be able to work with plasmas.
That said, we are not any closer than before to having anything we yet know how to build work at these temperatures or at this efficiency.
Also, I am sensing that there tends to be either a bit of indifference or inadvertency in the mixing of energy and power in discussing Fusion device outputs. With pulse type devices, this is a very common problem. Failing to properly integrate the input energy over the device's entire cycle, leds often to outragious and physically impossible claims of efficiencies... i.e.: > 100%.
I think all on this net are more or less aware of these pitfalls, so there's no need to preach on this subject.
Where there is a need to remain alert, is when we are adding up thermal energy..."heat".... without regard to temperature. Here you can get a real headache... because it is entirely possible to move more low grade heat than you put into something... because along the way in the process, mechanical work, electrical energy, mass, etc.... was converted into low grade heat. The heat pump is the obvious example... moving more heat than the equivalent elecrical or fuel energy that was in put.
The amount of work that a low temperature device can do.. approaches zero, as the high temperature of the device approaches the temperature at which heat is to be rejected.
The amount of heat that such a device can pass, while doing almost zero work... increases without limit, as the high temperature approaches the low temperature limit.
So... where all we need is heat, we should use devices that pass through.. heat. Where we need work, we have to worry about how "hot" (temperature) the heat is, and hence the Carnot efficiency.
But we need to always remember the Carnot efficiency is the theoretical limiting efficiency... the bogey... not the achievable day in -day out practical operating efficiency... We do well usually to approach 75% of Carnot efficiency with most devices.
Hope this is useful..
Dave Cooper
Re: What makes the H-bomb so efficient? A: (with some math)
Sorry, by "insane" I meant 50+%, which is outside what any other
thermal to electricity system has done. 1300k to 300k could be ~75%
efficient and is inside normal temperature ranges, but when we are
talking about 42,000,000 Kelvin > 300k your not really limited by the
Carnot Cycle's limit of 99.999%. I was pointing out that there are
other systems that you can use that are not what people think of as
"thermal" systems. AKA Solar cells are limited by the Carnot Cycle
just like steam systems, but Solar cells don't touch the "hot" side of
that system.
Anyway, JET operated in bursts that lasted up to 60 seconds and
ITER should hit 1000+ seconds so the there is less need to focus on
"burst" power vs. power over time.
Check out http://www.jet.efda.org/documents/wesson/wesson.html
for a good look at JET’s past. It looks at the history of JET vs it’s
best operating conditions so there is a lot of graphs at the lower
operating conditions. Most of the time was spent on R&D in a non
fusion burn so that they could avoid activating the materials. On page
167 you see where they look at the energy used to increase the
plasma temperature vs. maintain the plasma temperature in which
case the Q turns out to be .9 vs. .6 when you integrate to get net
power input vs. net heat output. But they stick with the “real” value of
.6 for the reasons you stated. Anyway, this is so much better than the
1950’s starting value of Q=10 ^ - 12 that I think there is real hope that
they are on to something.
As to net power efficiency I think that we are going to be limited by
the use of beryllium systems but it can take fairly high heat loads so
40% thermal efficiency is not out of the question. ITER is so much
larger than JET that they are almost at ignition vs. breakeven.
PS: At 75% heat > electricity efficiency JET could operate as a power
plant. But, I used 40% efficiency because there are well-tested
systems that operate at that level instead of trying to think of what a
good theoretical limit would be.
thermal to electricity system has done. 1300k to 300k could be ~75%
efficient and is inside normal temperature ranges, but when we are
talking about 42,000,000 Kelvin > 300k your not really limited by the
Carnot Cycle's limit of 99.999%. I was pointing out that there are
other systems that you can use that are not what people think of as
"thermal" systems. AKA Solar cells are limited by the Carnot Cycle
just like steam systems, but Solar cells don't touch the "hot" side of
that system.
Anyway, JET operated in bursts that lasted up to 60 seconds and
ITER should hit 1000+ seconds so the there is less need to focus on
"burst" power vs. power over time.
Check out http://www.jet.efda.org/documents/wesson/wesson.html
for a good look at JET’s past. It looks at the history of JET vs it’s
best operating conditions so there is a lot of graphs at the lower
operating conditions. Most of the time was spent on R&D in a non
fusion burn so that they could avoid activating the materials. On page
167 you see where they look at the energy used to increase the
plasma temperature vs. maintain the plasma temperature in which
case the Q turns out to be .9 vs. .6 when you integrate to get net
power input vs. net heat output. But they stick with the “real” value of
.6 for the reasons you stated. Anyway, this is so much better than the
1950’s starting value of Q=10 ^ - 12 that I think there is real hope that
they are on to something.
As to net power efficiency I think that we are going to be limited by
the use of beryllium systems but it can take fairly high heat loads so
40% thermal efficiency is not out of the question. ITER is so much
larger than JET that they are almost at ignition vs. breakeven.
PS: At 75% heat > electricity efficiency JET could operate as a power
plant. But, I used 40% efficiency because there are well-tested
systems that operate at that level instead of trying to think of what a
good theoretical limit would be.
-
Richard Hull
- Moderator
- Posts: 15034
- Joined: Fri Jun 15, 2001 9:44 am
- Real name: Richard Hull
Re: What makes the H-bomb so efficient? A: (with some math)
Since it has been real soon now for 50 plus years, we can all wait, I am sure, for this new iteration to show us the wonderful fusion future we have awaited.
Much as Dave noted engineers don't work off theory alone they work off of practicalities and realities coupled with the limits of material science and a load of ever present bean counters, bosses, overseers, etc. This is the first real layer in getting things from burst mode pulsed operations showing some distant promise to public usability. All this wonderment can be stopped at any layer beyond engineering for any number of reasons that relate to political, economic or other issues not having a thing to do with the glorious theory, the realizable science, the empirical proof of concept, the engineering, material science or even the intial bean counting. Many hurdles exist; way past the glory of JET or the ITER, regardless of operational reports.
Fission is a mature, well understood technology which has proved itself as a useful power source over many years and yet it lay dormant, not due to theory, science, engineering, bean counting or any of the other physical concerns associated with reason or logic. Fusion has much more of an uphill battle having never converted the first joule of fusion to a watt of juice.
Still, we are asked to empty our pockets and hold our breath, yet once again.
Richard Hull
Much as Dave noted engineers don't work off theory alone they work off of practicalities and realities coupled with the limits of material science and a load of ever present bean counters, bosses, overseers, etc. This is the first real layer in getting things from burst mode pulsed operations showing some distant promise to public usability. All this wonderment can be stopped at any layer beyond engineering for any number of reasons that relate to political, economic or other issues not having a thing to do with the glorious theory, the realizable science, the empirical proof of concept, the engineering, material science or even the intial bean counting. Many hurdles exist; way past the glory of JET or the ITER, regardless of operational reports.
Fission is a mature, well understood technology which has proved itself as a useful power source over many years and yet it lay dormant, not due to theory, science, engineering, bean counting or any of the other physical concerns associated with reason or logic. Fusion has much more of an uphill battle having never converted the first joule of fusion to a watt of juice.
Still, we are asked to empty our pockets and hold our breath, yet once again.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Re: What makes the H-bomb so efficient? A: (with some math)
I agree that politics will play a large role in the future of fusion but the
current view that fusion is a clean power source should help things
along. There are several independent programs that are activity
inspecting fusion and a vary positive outlook.
ITER should have a Q >= 10 which is well within the “useful” energy
range ~4x electricity out to electricity in. There will be issues with
contamination of the plasma due to sputtering from the walls. But,
containment time keeps going up. “The world record for pulse
duration is held by the TRIAM-1M tokamak in Japan, which ran for
more than three hours. However, the machine performed with an
injected energy of only 110 MJ and at a very low current, temperature
and density.” http://physicsweb.org/articles/world/17/1/6/1 (Controlled
fusion: the next step January 2004 IMO it's a good look at the wide
range of reactors being tested.)
“As of April, 2005, there are 104 commercial nuclear generating units
that are fully licensed by the U.S” So, I don’t think of Fission as a
dormant power source. It’s currently a heavily subsidized power
source that’s not directly competitive with coal power due to the risks
of contamination and the cost of dealing with waste. I agree that there
is a NIMBY problem with fission in the US but overall it’s much more
adopted than wind, solar, and hydro combined.
Anyway, I don’t expect fusion to reduce the price of electricity.
We have at least 100 years of coal and 1000 years of Fusion energy
on tap, so we are not “running out of energy.” With 40% efficient
sterling solar systems we have access to cheep and unlimited
energy right now.
http://pesn.com/2005/08/11/9600147_Edis ... est_solar/
The reason why I am interested in fusion is as a power plant for large
space ships, which is probably not going to happen till long after I am
dead. (I am 25 now, which means I am thinking well over 75 years on
that one.) Even if it takes 300 years we will soon enough reach for
the stars.
Building huge super conductors is a lot cheeper now than they where
30 years ago, computers are a lot cheaper, as are devices for the
remote handling of activated materials, and the world is a lot richer
now than it was 30 years ago. Right now Bill Gates could privately
fund ITER with the money he is giving to charity, in 50 years I expect
a wider range of people capable of privately funding such research.
Anyway, from the technical side things are looking good and from the
political side I am reasonably hopeful so I think the future is looking
good. With more funding we could probably see a working power
plant in 20 years, but even still once ITER demonstrates a useful
level of power gain people will have a hard time calling fusion a pie in
the sky dream. So, I expect funding to continue.
current view that fusion is a clean power source should help things
along. There are several independent programs that are activity
inspecting fusion and a vary positive outlook.
ITER should have a Q >= 10 which is well within the “useful” energy
range ~4x electricity out to electricity in. There will be issues with
contamination of the plasma due to sputtering from the walls. But,
containment time keeps going up. “The world record for pulse
duration is held by the TRIAM-1M tokamak in Japan, which ran for
more than three hours. However, the machine performed with an
injected energy of only 110 MJ and at a very low current, temperature
and density.” http://physicsweb.org/articles/world/17/1/6/1 (Controlled
fusion: the next step January 2004 IMO it's a good look at the wide
range of reactors being tested.)
“As of April, 2005, there are 104 commercial nuclear generating units
that are fully licensed by the U.S” So, I don’t think of Fission as a
dormant power source. It’s currently a heavily subsidized power
source that’s not directly competitive with coal power due to the risks
of contamination and the cost of dealing with waste. I agree that there
is a NIMBY problem with fission in the US but overall it’s much more
adopted than wind, solar, and hydro combined.
Anyway, I don’t expect fusion to reduce the price of electricity.
We have at least 100 years of coal and 1000 years of Fusion energy
on tap, so we are not “running out of energy.” With 40% efficient
sterling solar systems we have access to cheep and unlimited
energy right now.
http://pesn.com/2005/08/11/9600147_Edis ... est_solar/
The reason why I am interested in fusion is as a power plant for large
space ships, which is probably not going to happen till long after I am
dead. (I am 25 now, which means I am thinking well over 75 years on
that one.) Even if it takes 300 years we will soon enough reach for
the stars.
Building huge super conductors is a lot cheeper now than they where
30 years ago, computers are a lot cheaper, as are devices for the
remote handling of activated materials, and the world is a lot richer
now than it was 30 years ago. Right now Bill Gates could privately
fund ITER with the money he is giving to charity, in 50 years I expect
a wider range of people capable of privately funding such research.
Anyway, from the technical side things are looking good and from the
political side I am reasonably hopeful so I think the future is looking
good. With more funding we could probably see a working power
plant in 20 years, but even still once ITER demonstrates a useful
level of power gain people will have a hard time calling fusion a pie in
the sky dream. So, I expect funding to continue.
Re: What makes the H-bomb so efficient? A: (with some math)
I think that these discussions are interesting and almost always useful. They would be more so, IMHO, were they kept more on the analytical plane, as opposed to the conjectural plane.
The long awaited promise of the controlled, non-explosive fusion device, is still.... being awaited, as Richard has so patiently pointed out to us.
It seems to me most likely true, that the required investment into a new technology is directly related to not only its sophistication and hence difficulty, but also to its economic potential. The bigger the payoff, in all probability, the bigger the investment needed to achieve it.
So the enormous potential payoff of "fusion" could well require 10X what has been put into it already, before it yields its secrets and becomes availble to help the common man.
But whether it can or will ever do this... is the BIG question that we labor to answer. Today, I think we are still in the "Reasonable Experiment Mode", which may be all we can expect at this point in time. The people who are stitching together economic justifications for the purposes of getting funding approvals, are more or less forced to play the game, or.. give up.
The work only becomes an embarassment in my opinion, when it is mis-represented in the technical community. That should stop.
The study of "mortar" while not particularly intesting, and would hardly win any architectural awards, is downright important to all building practices. Some of these fusion experiments, may just be "a study of mortar"... and not architecturely interesting, yet.
Nice discussion, thanks to all.
Dave Cooper
The long awaited promise of the controlled, non-explosive fusion device, is still.... being awaited, as Richard has so patiently pointed out to us.
It seems to me most likely true, that the required investment into a new technology is directly related to not only its sophistication and hence difficulty, but also to its economic potential. The bigger the payoff, in all probability, the bigger the investment needed to achieve it.
So the enormous potential payoff of "fusion" could well require 10X what has been put into it already, before it yields its secrets and becomes availble to help the common man.
But whether it can or will ever do this... is the BIG question that we labor to answer. Today, I think we are still in the "Reasonable Experiment Mode", which may be all we can expect at this point in time. The people who are stitching together economic justifications for the purposes of getting funding approvals, are more or less forced to play the game, or.. give up.
The work only becomes an embarassment in my opinion, when it is mis-represented in the technical community. That should stop.
The study of "mortar" while not particularly intesting, and would hardly win any architectural awards, is downright important to all building practices. Some of these fusion experiments, may just be "a study of mortar"... and not architecturely interesting, yet.
Nice discussion, thanks to all.
Dave Cooper