Posted: Fri Sep 11, 2009 8:15 pm
Are we sure it doesn't?I've never understood why 'annealing' doesn't happen in a fusor if it is going to work in Polywell.
a discussion forum for Polywell fusion
https://talk-polywell.org/bb/
Are we sure it doesn't?I've never understood why 'annealing' doesn't happen in a fusor if it is going to work in Polywell.
I was going to make the same comment but got distracted by connection problems. I have perused the Fusor.Net site and I have not seen any comments about 'annealing' in any context. Possibly a major difference is the numbers of neutrals present. In a glow discharge fusor there are alot of neutrals which are moving randomely in a thermalized distribution (perhaps at most a few eV ? (I assume the average temperature of the neutrals would be well below the ionization temperature)). There is no difference in the velocity in the center compared to the perifery of these neutrals, so I suspect that the dominate ion - neutral collisions would not lend itself to annealing. In an ion fed fusor (like the Hirsch Meeks efforts) presumably the neutral population would be much less. Dr Bussard mentioned in one of his papers some reasons why the Hirsch Meeks outproformed predictions by several orders of magnitude. I didn't understand his reasoning at the time. Other than ion-ion collisions presumably being more prevelent in an ion fed fusor, perhaps an annealing effect also contributes - vigerous hand waving hereTallDave wrote:Are we sure it doesn't?I've never understood why 'annealing' doesn't happen in a fusor if it is going to work in Polywell.
maybe he didn't understand his reasoning either - he didn't understand fusors don't work by ion-ion collisions, an erroneous presumption on which he based his design of the Polywell. (IMHO)D Tibbets wrote: Dr Bussard mentioned in one of his papers some reasons why the Hirsch Meeks outproformed predictions by several orders of magnitude. I didn't understand his reasoning at the time.
I'm not sure where you get that assumption. He has mentioned both effects. Also, I,ve not heard any counterargumnets concerning ion- neutral ratios in in ion gun fed systems versus electrostatic induced ionization in regular fusers.chrismb wrote:maybe he didn't understand his reasoning either - he didn't understand fusors don't work by ion-ion collisions, an erroneous presumption on which he based his design of the Polywell. (IMHO)D Tibbets wrote: Dr Bussard mentioned in one of his papers some reasons why the Hirsch Meeks outproformed predictions by several orders of magnitude. I didn't understand his reasoning at the time.
Which assumption? That he thought fusors worked by ion-ion reactions, or that he based his design to perform ion-ion reactions? The reality of the former is still difficult to convince many on even today (that it is mainly ion-neutrals in a fusor), the latter is implied (I thought?)D Tibbets wrote:I'm not sure where you get that assumption. He has mentioned both effects. Also, I,ve not heard any counterargumnets concerning ion- neutral ratios in in ion gun fed systems versus electrostatic induced ionization in regular fusers.chrismb wrote:maybe he didn't understand his reasoning either - he didn't understand fusors don't work by ion-ion collisions, an erroneous presumption on which he based his design of the Polywell. (IMHO)D Tibbets wrote: Dr Bussard mentioned in one of his papers some reasons why the Hirsch Meeks outproformed predictions by several orders of magnitude. I didn't understand his reasoning at the time.
Dan Tibbets
I think the annealing in the FUSOR does not have time to happen. The ions and electrons circulate back and forth trough the center only a few time, maybe ten or 20 time for what I have read. Annealing should takes 1000s to millions of passes before to be significant.TallDave wrote:Are we sure it doesn't?I've never understood why 'annealing' doesn't happen in a fusor if it is going to work in Polywell.
In that case, there would be a population of ions that begin to diffuse through velocity-space and are never 'annealed' back again. That would cause the rest of the contents of the reaction volume to cascade into diffusion through velocity-space - viz. would thermalise.Jboily wrote:I think the annealing in the FUSOR does not have time to happen. The ions and electrons circulate back and forth trough the center only a few time, maybe ten or 20 time for what I have read. Annealing should takes 1000s to millions of passes before to be significant.TallDave wrote:Are we sure it doesn't?I've never understood why 'annealing' doesn't happen in a fusor if it is going to work in Polywell.
Yes to both questions. Again I'm not sure why you assume there are alot of neutrals present in a Polywell. It is a given that neutrals above ~10^19 neutrals per cubic meter ( ~ 1 micron) will shut down the machine due to arcing. That taken with the target of ~ 10^22 ions per cubic meter needed for net power production mandates that there has to be a thousand ions per neutral within the machine. I believe this means that there would be 1 million ion- ion collisions per ion neutral collision. If these ion to neutral proportions cannot be maintained the whole system is a failure from the start and presumably the physicists involved (including the reviewers) would abandon the effort. I believe Bussard's work has shown this gradient (~100-1000) is possible, and Nebel's work has confirmed it ( internal densities vs external densities). This is a presumptive argument about neutrals not contributing significantly to the fusion output in the Polywell. I'm not sure how difficult it would be to directy measure this in the current low output machines, though I again assume that the review panel was satisfied that it was not a show stoper due to my above arguments, other arguments, or actual measurements.chrismb wrote:Which assumption? That he thought fusors worked by ion-ion reactions, or that he based his design to perform ion-ion reactions? The reality of the former is still difficult to convince many on even today (that it is mainly ion-neutrals in a fusor), the latter is implied (I thought?)D Tibbets wrote:I'm not sure where you get that assumption. He has mentioned both effects. Also, I,ve not heard any counterargumnets concerning ion- neutral ratios in in ion gun fed systems versus electrostatic induced ionization in regular fusers.chrismb wrote: maybe he didn't understand his reasoning either - he didn't understand fusors don't work by ion-ion collisions, an erroneous presumption on which he based his design of the Polywell. (IMHO)
Dan Tibbets