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| UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Fusion Power won't work.
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#2
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Fusion Power won't work.
On 7/12/2017 7:59 PM, harry wrote:
http://www.bbc.co.uk/news/science-environment-40558758 Kicked into the long grass. Not actually what it says, Harry. It *is* saying what I have been saying for a long time, that the science is difficult and the engineering even more so. It won't be cheap. And it will never be "nuclear power without the waste". But then little more than a couple of centuries ago it was seriously being argued that heavier than air flight was impossible (even though birds were managing to do it). And two hundred years ago, that humans would never travel faster than on horseback, either because of the stresses or that breathing would be impossible. I find it incredible that Paul Erlich (the population one) is setting himself up again as a forecaster, in spite of making the most spectacularly wrong forecasts about starvation only two decades ahead. As taxpayers, we should always be looking at expenditure on research, but I would certainly not pull the plug on ITER and its successors; just that we should continuously look at the balance between what we are spending on biochemistry, particle physics, cosmology, batteries, photovoltaics, etc. We should be funding the *very* smartest guys to look at the hard, blue skies stuff, just being pretty selective as to who makes the cut. To my mind, there are only two rules for life, at the personal level. You can't change the past, and you can't predict the future. |
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#3
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Fusion Power won't work.
It clearly works in the sun, cretin.
"harry" wrote in message ... http://www.bbc.co.uk/news/science-environment-40558758 Kicked into the long grass. |
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#4
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Fusion Power won't work.
"newshound" wrote in message o.uk... On 7/12/2017 7:59 PM, harry wrote: http://www.bbc.co.uk/news/science-environment-40558758 Kicked into the long grass. Not actually what it says, Harry. It *is* saying what I have been saying for a long time, that the science is difficult and the engineering even more so. It won't be cheap. And it will never be "nuclear power without the waste". But then little more than a couple of centuries ago it was seriously being argued that heavier than air flight was impossible (even though birds were managing to do it). And two hundred years ago, that humans would never travel faster than on horseback, either because of the stresses or that breathing would be impossible. I find it incredible that Paul Erlich (the population one) is setting himself up again as a forecaster, in spite of making the most spectacularly wrong forecasts about starvation only two decades ahead. As taxpayers, we should always be looking at expenditure on research, but I would certainly not pull the plug on ITER and its successors; just that we should continuously look at the balance between what we are spending on biochemistry, particle physics, cosmology, batteries, photovoltaics, etc. We should be funding the *very* smartest guys to look at the hard, blue skies stuff, just being pretty selective as to who makes the cut. To my mind, there are only two rules for life, at the personal level. You can't change the past, and you can't predict the future. Corse you can predict the future. You will die sometime. So will I. |
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#5
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Fusion Power won't work.
Rod Speed wrote:
"newshound" wrote in message o.uk... On 7/12/2017 7:59 PM, harry wrote: http://www.bbc.co.uk/news/science-environment-40558758 Kicked into the long grass. Not actually what it says, Harry. It *is* saying what I have been saying for a long time, that the science is difficult and the engineering even more so. It won't be cheap. And it will never be "nuclear power without the waste". But then little more than a couple of centuries ago it was seriously being argued that heavier than air flight was impossible (even though birds were managing to do it). And two hundred years ago, that humans would never travel faster than on horseback, either because of the stresses or that breathing would be impossible. I find it incredible that Paul Erlich (the population one) is setting himself up again as a forecaster, in spite of making the most spectacularly wrong forecasts about starvation only two decades ahead. As taxpayers, we should always be looking at expenditure on research, but I would certainly not pull the plug on ITER and its successors; just that we should continuously look at the balance between what we are spending on biochemistry, particle physics, cosmology, batteries, photovoltaics, etc. We should be funding the *very* smartest guys to look at the hard, blue skies stuff, just being pretty selective as to who makes the cut. To my mind, there are only two rules for life, at the personal level. You can't change the past, and you can't predict the future. Corse you can predict the future. You will die sometime. So will I. Stupid Australian trolling ****. FOAD as soon as possible. https://www.sensationbot.com/jschat.php?db=rodspeed |
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#7
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Fusion Power won't work.
On 7/13/2017 9:10 AM, Jethro_uk wrote:
On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... Yes but it will need refuelling in five billion years :-) |
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#8
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Fusion Power won't work.
On 13/07/2017 09:10, Jethro_uk wrote:
On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... You could use solar panels to collect the light. All you need is a ring of panels around the equator a few miles wide. |
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#9
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Fusion Power won't work.
On 12-Jul-17 7:59 PM, harry wrote:
http://www.bbc.co.uk/news/science-environment-40558758 Kicked into the long grass. An improvement on 50 years away, as it used to be. -- -- Colin Bignell |
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#10
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Fusion Power won't work.
In article ,
newshound writes On 7/12/2017 7:59 PM, harry wrote: http://www.bbc.co.uk/news/science-environment-40558758 Kicked into the long grass. Not actually what it says, Harry. Harry never actually reads the articles to which he posts links -- bert |
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#11
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Fusion Power won't work.
In article , Jethro_uk
writes On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... God almighty!! -- bert |
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#12
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Fusion Power won't work.
On Thursday, 13 July 2017 22:31:10 UTC+1, bert wrote:
In article , Jethro_uk writes On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... God almighty!! Yep maybe he has some spare energy to send us. |
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#13
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Fusion Power won't work.
In article ,
whisky-dave writes On Thursday, 13 July 2017 22:31:10 UTC+1, bert wrote: In article , Jethro_uk writes On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... God almighty!! Yep maybe he has some spare energy to send us. Keel University have just discovered a star with the smallest possible mass theoretically capable of supporting fusion. -- bert |
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#14
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Stars and Fusion, Martin Brown?
On 7/17/2017 9:46 PM, bert wrote:
In article , whisky-dave writes On Thursday, 13 July 2017 22:31:10 UTC+1, bert wrote: In article , Jethro_uk writes On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... God almighty!! Yep maybe he has some spare energy to send us. Keel University have just discovered a star with the smallest possible mass theoretically capable of supporting fusion. https://www.keele.ac.uk/pressrelease...-as-saturn.php The only thing I am slightly skeptical about is the claim about fusion. Since fusion is energetically favourable, isn't it always going to occur at some rate because of tunnelling, it's just that the rate will drop off very rapidly with decreasing density. Is there actually a threshold? I thought it had been claimed that there could be a small amount of fusion at the centre of Jupiter. Is there any fundamental difference between a star and a gas planet (obviously the chemistry, and I use that word in the broadest form, will depend on the temperature distribution). |
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#15
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Fusion Power won't work.
On Monday, 17 July 2017 21:52:57 UTC+1, bert wrote:
In article , whisky-dave writes On Thursday, 13 July 2017 22:31:10 UTC+1, bert wrote: In article , Jethro_uk writes On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... God almighty!! Yep maybe he has some spare energy to send us. Keel University have just discovered a star with the smallest possible mass theoretically capable of supporting fusion. Still a hell of a long extention lead, I wouldn't like to PAT test that ;-) |
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#16
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Fusion Power won't work.
In article ,
whisky-dave writes On Monday, 17 July 2017 21:52:57 UTC+1, bert wrote: In article , whisky-dave writes On Thursday, 13 July 2017 22:31:10 UTC+1, bert wrote: In article , Jethro_uk writes On Thu, 13 Jul 2017 08:23:32 +0100, Brian Gaff wrote: Fusion works but the extreme conditions it produces are hard to both contain and remove the energy from efficiently. Those have always been the problems. I remember seeing what happens to ever super high temperature materials just a short way away from a fusion bomb. The stuff goes brittle and its make up changes significantly. I mean if you get cracks in stuff in fission reactors with normal radiation over decades then goodness knows what is going to happen to a fusion containment system! You will always have radiation unless you can find some way to stop it affecting the material at all. What you obviously need is Unobtainium! grin. Brian One idea might be to site the fusion reactor off-earth, and just transmit the energy back down ..... God almighty!! Yep maybe he has some spare energy to send us. Keel University have just discovered a star with the smallest possible mass theoretically capable of supporting fusion. Still a hell of a long extention lead, I wouldn't like to PAT test that ;-) Think of the ex's to get to the other end. -- bert |
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#17
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Stars and Fusion, Martin Brown?
On 17/07/2017 22:04, newshound wrote:
On 7/17/2017 9:46 PM, bert wrote: Keel University have just discovered a star with the smallest possible mass theoretically capable of supporting fusion. https://www.keele.ac.uk/pressrelease...-as-saturn.php The only thing I am slightly skeptical about is the claim about fusion. Since fusion is energetically favourable, isn't it always going to occur at some rate because of tunnelling, it's just that the rate will drop off very rapidly with decreasing density. Is there actually a threshold? Not a threshold as such but the effect of exp(-large number) cannot be overstated. They are incidentally claiming the star is small, hot and dense enough at the core to just sustain hydrogen burning fusion which is the classical definition of a main sequence star. In the initial phase of stellar collapse there are a bunch of other nuclear fusion reactions that have lower activation energies but very limited fuel supplies (basically traces of other light elements from the initial big bang and any stuff that has already been through a star). It is actually these initial starter reactions that people try to recreate on earth as fusion power. The old definition of a reaction being important in a star has an average lifetime of 50000 years. D2 + H1 - He3 + 5.5 MeV @ 10^6 K Li6 + H1 - He3 + He4 + 4.0 MeV @ 3x10^6 K Li7 + H1 - 2He4 + 17.3 Mev @ 4x10^6 K And others that burn Be9, B10, B11 at under the magic 10^7 K. The second of these is the igniter step in thermonuclear fusion weapons and is the reason why you cannot trust the isotopic ratio of laboratory lithium reagents to be natural. Once the core gets to 10^7 degrees then true main sequence hydrogen burning begins - but it is incredibly slow in a borderline mass star. Stars have burn times that vary inversely with their mass. The region capable of sustaining fusion requires high pressure and temperature is much larger in a big massive star so they burn bright and quickly. https://en.wikipedia.org/wiki/Stella...eir_masses.svg H1 + H1 - D2 + 1.44 MeV lifetime 14x10^9 y At this core temperature the D2 lasts about 6s before it is consumed. (cf about 50000 years at 10^6 K) If the core manages to get up to around 2x10^7 K then the CNO cycle can run like in our own sun with a faster hotter burn rate of hydrogen. Later still core collapse to get T ~ 10^8 allows helium burning and successive shells burning around it of lighter elements. When the core becomes mostly iron the star is in serious trouble and depending on its mass becomes a white dwarf or supernova. I thought it had been claimed that there could be a small amount of fusion at the centre of Jupiter. Is there any fundamental difference between a star and a gas planet (obviously the chemistry, and I use that word in the broadest form, will depend on the temperature distribution). Only one of mass and core temperature. The smallest star has a mass that is reckoned to be about the same as the heaviest planet. Whether a star gets lucky and ignites hydrogen core burning or settles down to an ignominious long life as a brown dwarf without ever going bright is an area of active research - partly because dim stars make seeing planets near them easier. -- Regards, Martin Brown |
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#18
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Stars and Fusion, Martin Brown?
On 7/20/2017 9:04 AM, Martin Brown wrote:
On 17/07/2017 22:04, newshound wrote: On 7/17/2017 9:46 PM, bert wrote: Keel University have just discovered a star with the smallest possible mass theoretically capable of supporting fusion. https://www.keele.ac.uk/pressrelease...-as-saturn.php The only thing I am slightly skeptical about is the claim about fusion. Since fusion is energetically favourable, isn't it always going to occur at some rate because of tunnelling, it's just that the rate will drop off very rapidly with decreasing density. Is there actually a threshold? Not a threshold as such but the effect of exp(-large number) cannot be overstated. They are incidentally claiming the star is small, hot and dense enough at the core to just sustain hydrogen burning fusion which is the classical definition of a main sequence star. In the initial phase of stellar collapse there are a bunch of other nuclear fusion reactions that have lower activation energies but very limited fuel supplies (basically traces of other light elements from the initial big bang and any stuff that has already been through a star). It is actually these initial starter reactions that people try to recreate on earth as fusion power. The old definition of a reaction being important in a star has an average lifetime of 50000 years. D2 + H1 - He3 + 5.5 MeV @ 10^6 K Li6 + H1 - He3 + He4 + 4.0 MeV @ 3x10^6 K Li7 + H1 - 2He4 + 17.3 Mev @ 4x10^6 K And others that burn Be9, B10, B11 at under the magic 10^7 K. The second of these is the igniter step in thermonuclear fusion weapons and is the reason why you cannot trust the isotopic ratio of laboratory lithium reagents to be natural. Once the core gets to 10^7 degrees then true main sequence hydrogen burning begins - but it is incredibly slow in a borderline mass star. Stars have burn times that vary inversely with their mass. The region capable of sustaining fusion requires high pressure and temperature is much larger in a big massive star so they burn bright and quickly. https://en.wikipedia.org/wiki/Stella...eir_masses.svg H1 + H1 - D2 + 1.44 MeV lifetime 14x10^9 y At this core temperature the D2 lasts about 6s before it is consumed. (cf about 50000 years at 10^6 K) If the core manages to get up to around 2x10^7 K then the CNO cycle can run like in our own sun with a faster hotter burn rate of hydrogen. Later still core collapse to get T ~ 10^8 allows helium burning and successive shells burning around it of lighter elements. When the core becomes mostly iron the star is in serious trouble and depending on its mass becomes a white dwarf or supernova. I thought it had been claimed that there could be a small amount of fusion at the centre of Jupiter. Is there any fundamental difference between a star and a gas planet (obviously the chemistry, and I use that word in the broadest form, will depend on the temperature distribution). Only one of mass and core temperature. The smallest star has a mass that is reckoned to be about the same as the heaviest planet. Whether a star gets lucky and ignites hydrogen core burning or settles down to an ignominious long life as a brown dwarf without ever going bright is an area of active research - partly because dim stars make seeing planets near them easier. Thanks, very interesting! I was very keen in astronomy as a kid, but never really thought of it as a career for a physicist. I knew my maths was never going to be up to doing cosmology and, even by 1970, Mount Palomar was still more or less state of the art optics (although Schmidts were getting interesting). I didn't forsee where electronics and computers were going to lead! |
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