Talk:Polywell/Archive 1

message: It should be noted that the controversial paper(s) referenced in main article where written over 12 years ago. The entire section should be considered for removal. --Nbritton 19:28, 12 May 2007 (UTC)
replies: text: That's not the way the Wikipedia works. Papers don't get removed because they are 12 years old. Only if you can find a paper that contains maths and so forth that proves the paper wrong, and which is generally accepted. And even then, linking to the original paper saying that it has been superseded is probably the way to go. WP:NPOV  WolfKeeper 19:53, 12 May 2007 (UTC)
replies: text:  That's what I'm saying! We have 12 years of new research with new designs, someone needs to check if the papers by Todd Rider are still applicable... and have it be noted in the main article. --Nbritton 09:15, 13 May 2007 (UTC)

text: Not quite what I said.  Bussard describes the "annealing" process (maxwellianization of the ions at low kinetic energy at the "top" of the well) as a means of removing any kinetic energy distribution induced by collisions elsewhere (addressing Rider's assertion that the plasma will maxwellianize and that this will result in some ions upscattering and being lost).  Bremsstrahlung is not affected by this.  Below, I give a link to a repository of DTIC reports, which includes at least two by Bussard and King regarding bremsstrahlung and how to minimize it.  Different mechanism.  Tom Ligon Tomligon 23:41, 14 June 2007 (UTC)
thread_title:  Todd Rider 

message: These are covered under fair use.
(Images placed in article.)
The diagrams in the paper, are, unfortunately, completely illegible.  I'm not sure what I think about that... — Omegatron 20:26, 14 December 2006 (UTC)
replies: text: Here's an image of WB-1, made with permanent magnets.  (Taken from )  You can see the electron burns where the magnetic field cusp intersects the surface: WB-1  71.41.210.146 03:28, 8 May 2007 (UTC)
thread_title:  Images from the paper 

message: For the fusor: "Without the motion of electrons and magnetic fields, there are no synchrotron losses and low levels of bremsstrahlung radiation."
But... the polywell uses magnetic fields to redirect electrons.  So wouldn't it suffer from these losses? — Omegatron 15:23, 18 December 2006 (UTC)
replies: text:  There are few that doubts that these devices do fusion, resulting in production of a lot of neutrons, but we have had that on some level for many years. What miss are the principles and math (rather than just the pictures, remember Lord Kelvin on numbers....) to show how they plan to meet the Lawson criterion and represent a leap change in sustainable net energy output. If not it is just a better "steam engine". The polywell seems to have some potiential in the area of recirculation. But unless they have some novel underlying theory; bremsstrahlung will still drain the energy of the fuel and ash ions. Somewhat simplified bremsstrahlung happens as moving charged particles form dipoles that change orientation and length which results in the emission of electromagnetic radiation. Unfortunately it does not matter what particles move as long as there are relative speeds. At fusor energy levels, heavy ions are not a problem in themselves, but electrons are a real pain. As an p-11B enthusiast myself it would interrest me immensely e.g. to see some novel electron draining or shielding principles, rather than the plumbing equipment and the conspiration that is hinted here.Haade 15:41, 26 December 2006 (UTC)
replies: text:  I believe that the key to the low bremsstrahlung levels is the somewhat anisotropic distribution of the plasma in the device. The ions and the electrons are being contained by two different methods: electrostatically for the ions, magnetically for the electrons. The electron density increases as you approach the core, and should be fairly stable, given enough re-injection to account for the inevitable electron losses, and a stable magnetic field. The ion density should be almost inverse, though the net charge in the core should be slightly positive to maintain a virtual anode once the fuel ions are injected. The ions will spend a great deal of their time approaching a zero kinetic energy state as the approach the grid and decelerate. This counterbalance of ion vs. electron motion should anneal out any lost ion energy to bremsstrahlung, though it may effect electron lifetimes in the core. As far as the fusion products go, in D-D the neutrons shouldn't be affected significantly by bremsstahlung, but remains to be seen if the alphas generated by p-B11 fusion will be greatly affected. As the alphas should be strongly attracted to the walls of the device, the decrease in electron density as you approach the grid and the hopefully neutral-free zone outside the device should reduce any alpha energy lost to bremsstrahlung to manageable levels. But wether or not this is the case hasn't been published by Bussard as of yet. That's just my best guess. — Blane Dabney 19:02, 15 May 2007 (UTC)
replies: text: A number of what are apparently internal reports pertaining to the HEPS device have turned up available at DTIC (http://stinet.dtic.mil/).  Search for "Bussard" and scan the titles for available .pdf files of interest.  Among them are a pair from 1991 on the subject of bremsstrahlung and syncrotron radiation.  Brem is a problem when you get fast electrons at high density, particularly in the presence of high Z nuclei.  The brem objections apparently come from the p-B11 case on the presumption that the electrons at the core of the device are at high energy, and B qualifies as high-Z.  In fact, to produce a potential well, the electrons must give up kinetic energy (due to coulomb repulsion from the high density of electrons there).  If you have the well at the full depth allowed by space-charge limitation, the electrons will have nearly zero kinetic energy there.  For the p-B11 case, Bussard and King show the calculations and demonstrate that it is important to keep the virtual anode height (due to convergence of the ions) below 0.15 of the potential well depth (i.e. control ion production to achieve lower ion density in the convergence region), and also run considerably hydrogen-rich.  Both of these measures reduce the fusion power output, and this is compensated for by increasing the machine size, probably the reason Bussard says the p-B11 machine must be larger than a DD machine. Tom Ligon Tomligon 23:43, 14 June 2007 (UTC)
thread_title:  Losses 

message: Looks like Bussard has won an award for the Polywell from the International Academy of Science! I have added the reference to the article.JulesVerne 13:30, 5 March 2007 (GMT)
: There are several organizations with the same name, and the consensus around here seems to be that this award is not very important.  See Talk:Robert W. Bussard#Outstanding Technology of the Year Award - 2006. — Omegatron 19:24, 6 April 2007 (UTC)
thread_title:  Award 

message: I'm chewing the fat with Eassin over to my place, and he asks "won't the magnetic field curve at the vertices leaving them unshielded, and a source of electron losses?" That gets me to thinking. Is it at all possible to set up a magnetic field in a volume using only external coils in such a way that there are neither line cusps nor field nulls? Even if such a far-reaching mathematical result is not provable in general, won't the vertices of a polywell at least tend to be regions of low field and therefore critical areas for both electron loss rates and coil survival times? Applied to Bussard's design, that would be the points where the circular coils kiss. The currents in the two coils are opposed, so there is not much net current around to make any fields, and simple symmetry arguments rule out everything except a radial field there. Has anybody seen more than hand-waving from Bussard on exactly what his 3-D magnetic fields are? What is the mathematical definition of these "line cusps" he wants very much to avoid? --Art Carlson 12:08, 22 May 2007 (UTC)
replies: text: Indrek Mandre has been doing some computer modeling of the magnetic field lines in the Polywell, as well as some particle simulation. You can see some of his results here: http://www.mare.ee/indrek/ephi/. For an example of what the field lines look like at the corner cusps, look at this image: http://www.mare.ee/indrek/ephi/pcp_lic.jpg. This is a corner cross section of the Polywell, so the field lines on the left and right are between two of the solenoids. Where those fields approach the solenoid cross sections at the top and bottom demonstrates the field geometry at the corner cusps. — Blane Dabney 15:46, 25 May 2007 (UTC)
replies: text: These are interesting pictures.  A real important question is what is the plasma density at various locations.  It is contained in the center where there is almost no field, or does it stick on the magnetic field lines? If it is the second case, then this thing will perform worse than the Levitated Dipole.  This question could be answered simply by taking a photo.  Don't know if hydrogen would glow, but neon and argon would. Paul Studier 21:33, 14 June 2007 (UTC)
replies: text: Some fairly good photos of WB2 and WB4 in operation can be found in the Google talk summary posted at http://www.askmar.com/Fusion.html.  Once these machines hit the Paschen arc (glow discharge) condition that typically ends runs if background gas is allowed to get out of control, you can see the plasma pretty well.  I'm not sure it is visible in fusion operation (there should be virtually no recombination of ions and electrons to produce light in correct operation).  In the Paschen discharges, you can see the plasma follow electron paths.  Fainter traces exit the cusps and follow the magnetic field lines.  The glow inside the magrid is much brighter, illustrating the "wiffleball" confinement.  The wiffleball effect is explained as a behavior of the trapped electrons in the center of the machine:  once the density is sufficiently high, the electrons behave diamagnetically, that is they tend to exclude the magnetic field.  This results in them pushing the field back and opening up that low-field zone in the center.  This has the byproduct of partly closing down the cusp holes.  In the Paschen discharge modes, you may actually be able to see this effect.  Look for a photo of WB2 operating with a very intense blue glow inside.  The wiffleball effect is supposed to result in densities inside the device being several thousand time higher than outside.  Tom Ligon Tomligon 00:08, 15 June 2007 (UTC)
replies: text: I don't see what you describe in the picture "WB2 Operating, November 1994.  The light appears to be room lighting.  For example,  there is a moon shaped light in front of the coil on the right side.  Looks like glare from the glass.  There is a perfect circle of light in the center.  If that was plasma, it would be cusp shaped with points up, down, right and left. Paul Studier 03:22, 18 June 2007 (UTC)

text: About that whiffleball ... I understand that the electrons would be diamagnetic (though there could be some exceptions to this rule), which, I figure, would improve the confinement by making a higher mirror ratio even if the field near the coils is not changed. Is that the whole story? Bussard draws pictures of big holes becoming little holes. Is that supposed to be a geometrical statement or just an analogy between hole size in a ball and mirror ratio in a plasma device? Concerning the pretty pictures ... I have to keep reminding myself that this is a 3-D configuration, so lines close together in the drawing does not imply a high field. I still believe the magnitude of the field where the rings touch will be small and radial. --Art Carlson 10:35, 15 June 2007 (UTC)

text: Thanks. At least I hadn't seen this paper before. It verifies my suspicion that field nulls at the vertices would be a problem. The proposed solution is to not let the coils touch, but this (at a minimum) introduces the line cusps that Bussard earlier said were so important to avoid. This paper claims that the additional losses through the line cusps can be held small. It also claims that electrons must be recirculated, so that some electron density - but not too much - must exist exterior to the coils. The question of how much of that recirculating plasma is intersected by the feeds (electrical and cryogenic) to the coils is not addressed. It is also interesting to remember the argument about good confinement in the machine due to the inherent stability of plasmas in concave magnetic fields. This argument applies to the plasma in the interior, but not to the recirculating electrons, where transport-producing instabilities must be feared, or at least considered. In short, this paper makes clearer what the current thinking of the proponents is, but it doesn't make me any less pessimistic. --Art Carlson 11:45, 18 June 2007 (UTC)
thread_title:  Field nulls 

message: The link California likely to fund further Polywell work. has been debunked at .  I quote from Joe Strout, the administrator of the blog and obviously pro-Polywell: I got a call back from Bill Maile in the Governor's office. He spoke with the Governor's policy advisors, and in brief, the story is false. This is the first anyone in the Governor's office has even heard of the idea. ... Meanwhile, remember, you got the truth here first — disappointing truth though it is. Paul Studier 21:28, 29 July 2007 (UTC)
thread_title: California Funding

message: Some of the information in the 'future work' section is really exciting, but can we please have some citations? The bit about Bussard's widow and the team in Santa Fe is one long piece of original research.JulesVerne 22:08, 8th November 2007 (GMT)
Like I said earlier, the following is great news for fusioneers, and I'm hugely pleased at the apparent success of the work:
Dr. Bussard passed away on October 6, 2007. His work will be continued by the staff of physicists he was able to assemble at EMC2. Dolly Gray, who co-founded EMC2 with Bussard in 1985, and served as its president and CEO, has helped assemble the small team of scientists in Santa Fe. The group includes Rick Nebel, Jaeyoung Park, both physicists are on leave from LANL; Mike Wray, the physicist who ran the key 2005 tests, and Kevin Wray, who is the computer guru for the operation. The latest device, WB-7, is currently under construction at a machine shop in San Diego and will be shipped to Santa Fe, where a small group of scientists is setting up a testing facility. The device, like previous ones, was designed by engineer Mike Skillercorn.
Mike Skillicorn.  I fixed it. Tomligon (talk) 02:37, 3 February 2008 (UTC)
replies: text: I didn't add that content, but I know the source is an article in the New Mexican, a New Mexico newspaper.  I'll try to dig it up and cite.  —Preceding unsigned comment added by 205.234.189.1 (talk) 20:30, 23 January 2008 (UTC)
thread_title: Future Work

message: A diagram of the field and the confined plasma would be helpful  —Preceding unsigned comment added by 129.2.40.144 (talk) 22:16, 26 November 2007 (UTC)
thread_title:  image? 

message: Regarding this edit: "Claims" is OK, since I wouldn't take their hype at face value either without independent verification. I thought "offers for sale" would cover it, since they are offering it, whether they can actually deliver or not. It's just that there are now "my word against his" statements in the article, with a formulation slightly in favor of NSD because of the word "however". I just wanted to offer an explanation that they are maybe not referring to the same conditions, or even the same device. Unfortunately we don't have enough information to really decide what is going on. That's the difficulty of writing articles about topics that are not adequately covered by secondary sources. --Art Carlson (talk) 11:04, 24 January 2008 (UTC)
replies: text: My mentioning NSD was an attempt to put Polywells fusion rate in some context.  If anyone can find a reputable source for the neutron rate of a fusor, then we should use that instead. Paul Studier (talk) 21:26, 24 January 2008 (UTC)
replies: text: I found a reference from U of Wisconsin.  Fewer neutrons but much more reliable, IMHO. Results comparable to Polywell without the complications of the magnets.  Paul Studier (talk) 01:43, 25 January 2008 (UTC)
thread_title:  NSD claims