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The list of fusioneers at the bottom of the article needs to be moved to its own page. Enough people have built this device that including a (partial) list of people to build this device falls outside the scope of this page and reads like an achievement list. I have restored the tag that I put up last month, which was removed by an unregistered user. — Preceding unsigned comment added by Bencbartlett ( talk • contribs) 16:25, 7 August 2015 (UTC)
I think we should remove the list altogether and include only the first few who built it, it's getting quite long. ThatGirlTayler ( talk) 05:04, 10 March 2017 (UTC)
An electron volt is a unit of energy. How can it be equal to 11604 degrees? - phma
Temperature measures the kinetic energy of particles' vibration. E = (mv^2)/2, so a particle's velocity is the most important factor in a material's temperature. All electrons have the same mass, so the mass drops out of the picture. So, an electric field will accelerate an electron to a speed which is proportional to a temperature. By the way, thanks to the person who rewrote it, knew about the history, bremstrahlung losses and got the picture. It's much improved. User:Ray Van De Walker
Specifically, E = (3/2)kT, where T is the temperature in Kelvins and k is Boltzmann's constant. 1 eV is equal to 1.6022e-19 Joules. Rearranging the equation,
.
Hmm. So either I'm wrong or the article's wrong, or we're talking about different things. At least it's the same order of magnitude. -
mako
It isn't "Kelvins", it is "Kelvin".
The last expression as a temperature converted from electron volts should be added to the article - Dan
in which the "wall" fields of the reactor were "electrons" or " ions" being held
What's up with the "fusion power" box? (replicated here)
Energy source | |
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Fusion power | |
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It's almost totally content-free (even with my additions), it's basically wrong, and it's irrelevant to the page - nobody has any idea how to extract power from fusors, and it's not what they're for. I'll take it out, and if anyone can explain why it should be there, feel free to do so and then put it back. Andrew 22:23, Dec 1, 2004 (UTC)
What particularly interested Farnsworth about the device was its ability to focus "electrons" at a particular point (for example, between nuclei).
What does the above mean? Again why the quotes? -- Gbleem 18:02, 18 Dec 2004 (UTC)
The article currently claims: "Fluxes well in excess of most radiological sources can be made from a machine that easily sits on a benchtop." Unless someone has some references supporting this claim, I believe this sentence should be removed. I am not aware of any real neutron beamline that uses a Fusor (they all use nuclear reactors or particle accelerators). As far as I know, the flux from a Fusor is much much lower than a particle accelerator or reactor. Real beamlines produce >1E14 neutrons/second out of each tube, whereas a Fusor generates maybe ~1E2 neutrons/second. If anyone has some real data that says otherwise I'd love to see it! Kebes 22:16, 27 Apr 2005 (UTC)
Interesting. That's not much flux! I also found one source that stated 1E8 neutrons/second, and another (seemingly from Los Alamos) that claims 1E10 neutrons/second. Since a Fusor is small, we can assume an operating distance of only 1 meter, but this still gives us only 1E5 n/(cm^2 s). Neutron fluxes from nuclear reactors are now on the order of 2E15 n/(cm^2 s), and spallation sources on the order of 1E17 n/(cm^2 s) (see fig 1 here for info). Considering that the Fusor is 10 order of magnitude worse than (good-quality) nuclear reactors, I don't think it's fair to say that its flux is "well in excess of most radiological sources." If no one objects, I'm going to rephrase that. Kebes 16:33, 28 Apr 2005 (UTC)
Hello, I noticed under commercial applications it says "To date, the highest neutron flux achieved by a fusor-like device has been 3 × 1011 neutrons per second with the deuterium-deuterium fusion reaction" does this imply that the unit of flux is 3x10^11 N/cm^2 * s or that the total neutrons achieved across all this companys surface area was 3x10^11? If that is the case should the word flux be replaced with fluence? Overlander27 ( talk) 05:04, 11 September 2021 (UTC)
We should cover the info in this article, specifically the section "Fusion the Easy Way" and the info about Bussard. I'm going to try to find out what happened with that... - Omegatron 23:34, Apr 27, 2005 (UTC)
Overview:
Art Carlson's summary of Rider's paper
This was relevant to Bussard's version for some reason?
Has a summary explaining the two different types
It seems the term "Farnsworth-Hirsch fusor" only applies to the 1967 version, and not the the earlier or later versions. Should we rename to just " Fusor" or "Fusor tube" or Inertial electrostatic confinement? - Omegatron 16:35, Apr 28, 2005 (UTC)
This is my brief critique of the fusor from the perspective of a (former) fusion research physicist. It is pretty conventional, the sort of worries I would expect any plasma physicist to have, but it could possibly be considered original research. It would be very good if someone who works directly with these things could check it over. It may be that there are valid counter-arguments to some of my objections. Or, of course, even more important problems that I have overlooked. Art Carlson 08:14, 2005 May 4 (UTC)
An important question is how often an ion must slosh back and forth in the potential well before it undergoes a fusion reaction. If the number is too great, we must fear that it will first disappear by some other process, like hitting an electrode or scattering out of the well. The fusion mean free path is λfus = 1/nσfus. If we assume a pressure-limited containment, p = nkT < pmax, equate (3/2)kT with (1/2)mv², and don't worry too much about how we take our averages, we find that λfus is proportional to T3/2/<σv>, so the temperature that minimizes the fusion mean free path for any reaction is similar to that which maximizes the power density (see Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions). Let us do a calculation for D-T using the values T = 13.6 keV and <σv>/T2 = 1.24×10-24 m³/sec/keV². Then we have v = sqrt(3*(1.6e-19)(1.36e4)/(2.5*1.67e-27)) m/s = 1.25e6 m/s, and σ = (1.24e-24)/(1.25e6) = 1.0×10-30 m². Let us take a generous 100 atm = 107 Pa as the plasma pressure, so that n = 4.6 ×1021 m-3. Put it all together and we have λfus = 2.2×108 m. That means an ion would have to survive some hundred million reflections to have much chance of undergoing fusion. To be fair, one is investing about 13.6 keV and getting back 17.6 MeV when it works, so even a 2% burnup might be sufficient to produce net power. That would still require an ion to survive around a million reflections. Art Carlson 10:11, 2005 May 5 (UTC)
In terms of time, λfus/v = 176 s = 3 min. For comparison, the ion collision time is given by 1/νi = (4.8e-8 s-1)-1(n/cm-3)-1( λ)-1(Ti/eV)3/2(m/mp)1/2 = 1.1 ms. If the ions are contained long enough to have any serious probability of fusing, then they will be well-thermalized long before that. This estimate assumes classical Coulomb collisions. In fact, the counter-streaming ion beams will be unstable on the ion plasma time scale and thermalize within nanosconds. [2] Art Carlson 10:11, 2005 May 5 (UTC)
I was thinking about the idea that the particles go back and forth through the center the other day and realized it's kind of like lifting marbles up to the edge of a bowl and then dropping them in. They'll make many passes through the center of the bowl at no cost to you, until they happen to hit each other. Good analogy? - Omegatron 14:06, May 4, 2005 (UTC)
I just edited this argument into inertial electrostatic confinement. Comments? Objections? Art Carlson 16:38, 2005 May 8 (UTC)
Something screwy has to be going on here. When I put in n = 1e12 m-3, T = 13.4 keV, and <σv> = 1.24×10-24 m3/s/keV2, I get 230 fusion reactions per cubic meter per second, way below reported value of up to 1e10 neutrons per second. ?!?! Maybe somebody should check my math. Art Carlson 16:52, 2005 May 8 (UTC)
Let me try again. A potential well can hold either electrons or ions, but not both. I might tweak things with double wells, something like this:
__/\ /\__ \___/
I need three electrodes. The ions are confined, e.g. by the potential drop between electrodes 2 and 3, while the electrons are confined by the potential drop between 1 and 2. The advantage is that my big volume can be quasineutral and the troublesome regions of net charge are the size of the interelectrode spacing rather than the fusion volume. Anyway, I can't avoid having some volume that has an ion density comparable to that where fusion is happening but an insignificant electron density (or vice versa). I wind up with a limit on the density something like this:
where I don't want my potential difference ΔU to be more than, say 100 kV, and I can't make the size of my electrode structures δ less than, say, 1 cm. This is in fact the same formula I got when considering the Debye length, except that I now allow myself a potential a bit higher than the temperature and a scale length a bit smaller than the machine. Putting these values in, I find
This value, in turn, gives me a maximum of 6.8e11 neutrons per cubic meter per second. If the fusion volume is 1e-3 m^3, this gives about 10^9 neutrons per seond, which is in the right ball park.
The fact that I arrived at a similar formula looking at the problem two different ways, and the fact that my results do not seem to contradict experimental reports, give me some confidence that I am on the right track. It would mean that
If that doesn't damp your spirits, nothing will! Art Carlson 09:28, 2005 May 9 (UTC)
I uploaded two pictures from Bussard's patent for use in a future section about him... - Omegatron July 2, 2005 01:26 (UTC)
Help! I tried to edit a small part of the article, to add a little bit of text, and an error message occurred, after which, when the edit was accepted, the whole article was replaced! That was not my intention! Somebody please revert!
Could the fusor be used to provide neutrons for fission and produce power without a chain reaction and produce net power? -- Gbleem 13:54, 23 June 2006 (UTC)
Yes. The fusor's only commercial use so far is as a neutron source. I'm doing a three year long research project for high school on such a subject, although not necessarily for inducing a fission reaction. Such a use is certainly within reason. -- Liambowen 03:04, 18 July 2006 (UTC)
Strongly For -- Though there have been a few differing incarnations of IEC over the years (usually one variation per research group), to date they all have similar fusion rates for a given current and frankly there is no reason to believe any of them are particularly different. Fusor should redirect to IEC, and gridded IEC (Fusors), penning traps etc should have their own sections. -- Rpf 13:00, 23 November 2006 (UTC)
I've heard of three devices; the IXL, EXL, and polywell types. Are all of these considered "fusors", or only the first? We either need to merge them all into one article or move the stuff that refers to non-fusors into the IEC article and vice versa. I think a merge is probably best. — Omegatron 15:52, 23 November 2006 (UTC)
Strongly against -- The devices vary greatly in design and considerations. Each has their own individual history. There are many designs. Consequently, you'll either have a monstrous article, or have to cut valuable detail. What you're proposing is like merging mice, rats, gerbils, etc into "Rodent" because they're similar.
The acronym IEC, apparently meaning "inertial-electrostatic confinement," should be defined in each article before it is used there. —Preceding unsigned comment added by 98.197.236.18 ( talk) 05:10, 16 March 2011 (UTC)
I have strong reservations about including the following statement:
In the reference given, this is the only line in 258 pages that so much as mentions recirculating power. The author does not even provide a reference to more detailed work, much less justify the statement himself. I don't remember the details of Rider's derivation, but I believe it was a lower limit that did not require an exact calculation of a particular distribution. If this is the only verifiable criticism we have of Rider's work, then I think we should leave it out altogether. At the very least it must be rephrased to make it clear that it is one voice, not a scientific consensus. -- Art Carlson 14:51, 23 November 2006 (UTC)
Is Rider's paper really applicable? As it stands, only nuclei are being accelerated by the grid -- not electrons. There are electrons in the grid, but that's hardly what he's talking about. In an "ideal" fusor, the electrons are completely ignored by the fusing ions. -- Rei 20:45, 28 November 2006 (UTC)
Rie, your argument appears to be based on two points; 1) that the issue of concern is Bremsstrahlung losses, and 2) that Ryder's critque doesn't apply because it's non-quasineutral. However, you haven't offered any evidence to actually support either claim. Quite the opposite, at the start of the thread you question whether not the Fusor really is quasineutral, and then dance around the point with these "ideal fusor" confusions. Nor do you ever address the question of whether or not the Bremsstrahlung losses could be calculated without the quasineutral assumption, yet this is a hidden requirement in your line of reasoning.
To answer your very first question, "Is Rider's paper really applicable?", the answer is an unqualified "yes". The paper is called "A General Critique of Inertial-Eletrostatic Confinement Fusion Systems". The paper addresses both the Fusor and the Bussard devices directly, with diagrams. Of course the later context suggests you're really asking whether or not it applies due to some sort of "mistake" in the calculators due to the quasineutral assumption. However if you examine the Spacial Profiles area of the paper, you will note that he addresses this issue directly, and shows mechanisms for electron mixing. Yet you recently stated "As the paper is about quasineutral plasmas". The paper is not "about quasineutral plasmas", and mentions them only in a theoretical section before directly addressing the problem in the lengthy discussion that follows. I cannot help but ask you the same question Art did, have you done your homework?
Based on what I have seen so far I will be inclined to revert any removal of Ryder's work based on these arguments. If you have a real point-by-point argument that covers these issues, I'm all ears. But in the meantime, removing material based on nothing more than the fact that Art hasn't replied yet (which is precisely the justification you offer above) strikes me as a breach of good-faith editing. Maury 23:12, 30 November 2006 (UTC)
← (My mistake, I meant 4.1.7.) A "spherical ion focusing system" sounds like IEC. Ref. 85 specifically mentions IEC ("infinite Brillouin ratio", "magnetic field vanishes everywhere", last page), and 86/87 certainly deal with IEC. "Dense fusion core", "unrealistically high fields"; it sounds like IEC to me. He's ruling it out based on real-world constraints. I guess this is the crux of the matter. We're talking about real fusors, not perfect ones. Do you agree that Rider's conclusions apply to IEC under current technology? Would you be satisfied if we made that distinction?
Let me also take a different tack. Rider specifically says that his results in "Fundamental limitations" rule out any kind of IEC breakeven. He's the one making the claim. It certainly meets WP:V. According to WP:NPOV, we put it in. If someone doesn't agree, they write something that meets V and we put it in. - mak o 02:14, 3 December 2006 (UTC)
The fusion reactor that he's looking for money for is obviously a decendant of the Fusor. The ions are still confined using electrostatic confinement but the light electrons are now confined using a magnetic field rather than the grid. It's a thousand times easier to confine electrons than it is to directly confine the ions because of the mass difference so even when the electrons are thrown out a near lightspeed they can be captured by the magnetic field and routed back into the 'core'. With an overabundance of electrons confined in the 'core' the ions don't really "want" to leave (ie electostatic confinement) so you get a ball of plasma rather than a 'star' as the ions evacuate.
There will of course still be large numbers of electrons lost, anything pointy or even just metal will appear to suck them right out but from the video it appear these losses can be kept down low enough to be replenished easily. The result; reaction rate going up at the SEVENTH POWER of the reactor size is definitly worthwhile!
So I think this should be added to this page in a more explicit manner but I can't think of a good way to do it without removing half the 'this cannot be used for fusion' parts.
86.16.135.53 08:55, 10 December 2006 (UTC)
I've added three {{fact}} for bold claims without sources given.
Pjacobi 08:24, 20 December 2006 (UTC)
My concern here is that some of these issues seem so minor that questioning them seems pendantic. I would be equally confused by a post suggesting the article on "bicycle" should be removed because it contains the unreferenced claim that Trek made a bike called the 5000. Whether or not there is a bike called the 5000 has no effect on the reality of bicycles as a whole. This example might seem trite, yet it appears that this is the logic being used to suggest the deletion of the German version of the fusor article, unless I'm seriously misunderstanding your point (which is certainly possible).
I will adress your points directly:
(1) seems more that well supported. But the real question is why do you need a better one? Do you really doubt that DASA might have provided some finding to a university researcher for some small-scale fusor research? You tagged it and called it a "bold" claim, and I am trying to understand what you feel is so bold. (2) who cares? If you don't think this claim isn't supported enough, remove it. It doesn't effect the article as a whole. (3) are you asking whether or not mainstream scientists "believe" in the fusor? If that is the question, then the answer is "yes" and it rates "mainstream". (4) well obviously yes. TEEN GOES NUCLEAR If you have some more stringent definition of what you mean here, you'll have to more clearly state it. (5) I can't read German very well though, but the "calculation" you mention appears to be one persons back-of-the-envelop musings. If you can translate it into English I'd appreciate it.
I have a question in return though, because I am still thinking much of my confusion is a language issue. So let me try to make this succinct. Pjacobi, do you personally feel that the fusor is not capable of producing limited amounts of fusion and the neutrons that result from them? IE, do you feel that the fusor is basically a scam? Please be clear on this; after two messages I am more confused than ever about your position. If you do doubt the existence of fusion events in the fusor, can you explain why? Is it, as you seem to suggest, due to that single post on the German wiki?
Maury 22:47, 21 December 2006 (UTC)
I just got an e-mail from George H.Miley. He confirmed that DASA was indeed funding part of his research and were indeed planning on using it for a commercial fusion source. They eventually decided not to pursuit it, but George continues to working field. He had heard that some of the DASA people left, notably John Sved, but had not heard of NSD. I consider this to be more than enough confirmation of the story. Maury 01:11, 27 December 2006 (UTC)
Here's an amateur project by a high school student. According to this article, it does not produce net power output, but it is a true fusion reactor of the Farnsworth type. Have fun adding it. -- 205.201.141.146 18:10, 16 February 2007 (UTC)
Demining#Nuclear_detection says "A better neutron source is to use a sealed tube electrostatic D-T neutron generation tube". Is this a fusor? — Omegatron 05:08, 13 August 2007 (UTC)
IEEE Spectrum 03.09 (March 2009) issue Pages 20-21 by Paul Wallich, feature title: "hands on" (lower cased), article title "Fusion on a Budget", describes the Fusor.
Hey guys, ETW fusors are a misnomer. They only modeled these machines. They never built one. Here is their original paper: William, Elmore C. "On the Inertial-Electrostatic Confinement of a Plasma." Physics of Fluids ser. 2 (1959): 239-46. Web. I think we need to somewhat disconnect the ETW design from the fusor and shift the article to fusors being built by amateurs and professionals today. These are all Hirsch machines, but we need to clear up that confusion as well. A Fusor is a negative cage inside a positive cage in a vacuum chamber. That is what is being built around the world. The path to this machine is less important, compared with information about the machine that is working now.
Taylor Wilson is the most well know amateur fusioneer. He did win a science fair for his construction of a fusor, he was on CBS news (3/30/2013) for the work and he did present this to the president at an event at the white house. So why has his photo been taken down from the amateur fusor section of this page? — Preceding unsigned comment added by 69.205.70.3 ( talk) 14:10, 13 August 2013 (UTC)
This one might be interesting enough to add, Conrad Farnsworth. Here's his story: http://trib.com/lifestyles/home-and-garden/teen-makes-nuclear-reactor-in-dad-s-shed/article_e9576aa3-9df4-550a-9778-29c4843104ed.html AE7EC ( talk) 02:59, 11 January 2014 (UTC)
Look, there are plenty of people who are working on fusors. But, this wikipedia article should limit itself to amateurs who have actually done fusion, actually detected neutrons. This is still not a small list of people (somewhere in the region of 75, or higher) and it is also a bit dicey, since these people are often self-reporting. Richard Hull maintains a list and he places rules, there are different hoops you have to get through, first vacuum, first glow and first nuetrons, ect... and the folks have to demonstrate progress along this path, to move forward. Amatuers should be listed if they get covered by the local news, or win a science fair, or a win a well known science scholarship, because they detected neutrons created by fusion. — Preceding unsigned comment added by WikiHelper2134 ( talk • contribs) 15:05, 28 January 2014 (UTC)
The article has a glaring omission by not describing the safety issues concerned with the building and operation of a Fusor. In addition to potentially-lethal levels of high-voltage electricity, there are issues concerning x-ray and ultra-violet radiation exposure when a unit is operated at high neutron-flux levels.
A simple search reveals that to date there are more than TWELVE HUNDRED posts that invoke the word “safety.” What is interesting is that, near as I can tell, there is no “FAQ” set that specifically addresses the safety considerations that should be taken in to account when building and operating one of these things.
Paul Schatzkin, FUSOR.NET, TAG ARCHIVES: SAFETY, [7].
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After reading the material in the Talk section on Plasma Physics and in other sections contributed by Art Carlson (which do an excellent job at de-bunking this body of work), I would seriously suggest that this whole article on Fusors and the like be downgraded in importance and perhaps should NOT be part of the Physics Portal. The article is valid in its own right as a historical account in Inventions. The article cites many contentious and dubious sources. In my opinion, this can be lumped with "Cold Fusion" and other dubious science. MxBuck ( talk) 00:47, 20 October 2019 (UTC)
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The list of fusioneers at the bottom of the article needs to be moved to its own page. Enough people have built this device that including a (partial) list of people to build this device falls outside the scope of this page and reads like an achievement list. I have restored the tag that I put up last month, which was removed by an unregistered user. — Preceding unsigned comment added by Bencbartlett ( talk • contribs) 16:25, 7 August 2015 (UTC)
I think we should remove the list altogether and include only the first few who built it, it's getting quite long. ThatGirlTayler ( talk) 05:04, 10 March 2017 (UTC)
An electron volt is a unit of energy. How can it be equal to 11604 degrees? - phma
Temperature measures the kinetic energy of particles' vibration. E = (mv^2)/2, so a particle's velocity is the most important factor in a material's temperature. All electrons have the same mass, so the mass drops out of the picture. So, an electric field will accelerate an electron to a speed which is proportional to a temperature. By the way, thanks to the person who rewrote it, knew about the history, bremstrahlung losses and got the picture. It's much improved. User:Ray Van De Walker
Specifically, E = (3/2)kT, where T is the temperature in Kelvins and k is Boltzmann's constant. 1 eV is equal to 1.6022e-19 Joules. Rearranging the equation,
.
Hmm. So either I'm wrong or the article's wrong, or we're talking about different things. At least it's the same order of magnitude. -
mako
It isn't "Kelvins", it is "Kelvin".
The last expression as a temperature converted from electron volts should be added to the article - Dan
in which the "wall" fields of the reactor were "electrons" or " ions" being held
What's up with the "fusion power" box? (replicated here)
Energy source | |
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Fusion power | |
|
It's almost totally content-free (even with my additions), it's basically wrong, and it's irrelevant to the page - nobody has any idea how to extract power from fusors, and it's not what they're for. I'll take it out, and if anyone can explain why it should be there, feel free to do so and then put it back. Andrew 22:23, Dec 1, 2004 (UTC)
What particularly interested Farnsworth about the device was its ability to focus "electrons" at a particular point (for example, between nuclei).
What does the above mean? Again why the quotes? -- Gbleem 18:02, 18 Dec 2004 (UTC)
The article currently claims: "Fluxes well in excess of most radiological sources can be made from a machine that easily sits on a benchtop." Unless someone has some references supporting this claim, I believe this sentence should be removed. I am not aware of any real neutron beamline that uses a Fusor (they all use nuclear reactors or particle accelerators). As far as I know, the flux from a Fusor is much much lower than a particle accelerator or reactor. Real beamlines produce >1E14 neutrons/second out of each tube, whereas a Fusor generates maybe ~1E2 neutrons/second. If anyone has some real data that says otherwise I'd love to see it! Kebes 22:16, 27 Apr 2005 (UTC)
Interesting. That's not much flux! I also found one source that stated 1E8 neutrons/second, and another (seemingly from Los Alamos) that claims 1E10 neutrons/second. Since a Fusor is small, we can assume an operating distance of only 1 meter, but this still gives us only 1E5 n/(cm^2 s). Neutron fluxes from nuclear reactors are now on the order of 2E15 n/(cm^2 s), and spallation sources on the order of 1E17 n/(cm^2 s) (see fig 1 here for info). Considering that the Fusor is 10 order of magnitude worse than (good-quality) nuclear reactors, I don't think it's fair to say that its flux is "well in excess of most radiological sources." If no one objects, I'm going to rephrase that. Kebes 16:33, 28 Apr 2005 (UTC)
Hello, I noticed under commercial applications it says "To date, the highest neutron flux achieved by a fusor-like device has been 3 × 1011 neutrons per second with the deuterium-deuterium fusion reaction" does this imply that the unit of flux is 3x10^11 N/cm^2 * s or that the total neutrons achieved across all this companys surface area was 3x10^11? If that is the case should the word flux be replaced with fluence? Overlander27 ( talk) 05:04, 11 September 2021 (UTC)
We should cover the info in this article, specifically the section "Fusion the Easy Way" and the info about Bussard. I'm going to try to find out what happened with that... - Omegatron 23:34, Apr 27, 2005 (UTC)
Overview:
Art Carlson's summary of Rider's paper
This was relevant to Bussard's version for some reason?
Has a summary explaining the two different types
It seems the term "Farnsworth-Hirsch fusor" only applies to the 1967 version, and not the the earlier or later versions. Should we rename to just " Fusor" or "Fusor tube" or Inertial electrostatic confinement? - Omegatron 16:35, Apr 28, 2005 (UTC)
This is my brief critique of the fusor from the perspective of a (former) fusion research physicist. It is pretty conventional, the sort of worries I would expect any plasma physicist to have, but it could possibly be considered original research. It would be very good if someone who works directly with these things could check it over. It may be that there are valid counter-arguments to some of my objections. Or, of course, even more important problems that I have overlooked. Art Carlson 08:14, 2005 May 4 (UTC)
An important question is how often an ion must slosh back and forth in the potential well before it undergoes a fusion reaction. If the number is too great, we must fear that it will first disappear by some other process, like hitting an electrode or scattering out of the well. The fusion mean free path is λfus = 1/nσfus. If we assume a pressure-limited containment, p = nkT < pmax, equate (3/2)kT with (1/2)mv², and don't worry too much about how we take our averages, we find that λfus is proportional to T3/2/<σv>, so the temperature that minimizes the fusion mean free path for any reaction is similar to that which maximizes the power density (see Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions). Let us do a calculation for D-T using the values T = 13.6 keV and <σv>/T2 = 1.24×10-24 m³/sec/keV². Then we have v = sqrt(3*(1.6e-19)(1.36e4)/(2.5*1.67e-27)) m/s = 1.25e6 m/s, and σ = (1.24e-24)/(1.25e6) = 1.0×10-30 m². Let us take a generous 100 atm = 107 Pa as the plasma pressure, so that n = 4.6 ×1021 m-3. Put it all together and we have λfus = 2.2×108 m. That means an ion would have to survive some hundred million reflections to have much chance of undergoing fusion. To be fair, one is investing about 13.6 keV and getting back 17.6 MeV when it works, so even a 2% burnup might be sufficient to produce net power. That would still require an ion to survive around a million reflections. Art Carlson 10:11, 2005 May 5 (UTC)
In terms of time, λfus/v = 176 s = 3 min. For comparison, the ion collision time is given by 1/νi = (4.8e-8 s-1)-1(n/cm-3)-1( λ)-1(Ti/eV)3/2(m/mp)1/2 = 1.1 ms. If the ions are contained long enough to have any serious probability of fusing, then they will be well-thermalized long before that. This estimate assumes classical Coulomb collisions. In fact, the counter-streaming ion beams will be unstable on the ion plasma time scale and thermalize within nanosconds. [2] Art Carlson 10:11, 2005 May 5 (UTC)
I was thinking about the idea that the particles go back and forth through the center the other day and realized it's kind of like lifting marbles up to the edge of a bowl and then dropping them in. They'll make many passes through the center of the bowl at no cost to you, until they happen to hit each other. Good analogy? - Omegatron 14:06, May 4, 2005 (UTC)
I just edited this argument into inertial electrostatic confinement. Comments? Objections? Art Carlson 16:38, 2005 May 8 (UTC)
Something screwy has to be going on here. When I put in n = 1e12 m-3, T = 13.4 keV, and <σv> = 1.24×10-24 m3/s/keV2, I get 230 fusion reactions per cubic meter per second, way below reported value of up to 1e10 neutrons per second. ?!?! Maybe somebody should check my math. Art Carlson 16:52, 2005 May 8 (UTC)
Let me try again. A potential well can hold either electrons or ions, but not both. I might tweak things with double wells, something like this:
__/\ /\__ \___/
I need three electrodes. The ions are confined, e.g. by the potential drop between electrodes 2 and 3, while the electrons are confined by the potential drop between 1 and 2. The advantage is that my big volume can be quasineutral and the troublesome regions of net charge are the size of the interelectrode spacing rather than the fusion volume. Anyway, I can't avoid having some volume that has an ion density comparable to that where fusion is happening but an insignificant electron density (or vice versa). I wind up with a limit on the density something like this:
where I don't want my potential difference ΔU to be more than, say 100 kV, and I can't make the size of my electrode structures δ less than, say, 1 cm. This is in fact the same formula I got when considering the Debye length, except that I now allow myself a potential a bit higher than the temperature and a scale length a bit smaller than the machine. Putting these values in, I find
This value, in turn, gives me a maximum of 6.8e11 neutrons per cubic meter per second. If the fusion volume is 1e-3 m^3, this gives about 10^9 neutrons per seond, which is in the right ball park.
The fact that I arrived at a similar formula looking at the problem two different ways, and the fact that my results do not seem to contradict experimental reports, give me some confidence that I am on the right track. It would mean that
If that doesn't damp your spirits, nothing will! Art Carlson 09:28, 2005 May 9 (UTC)
I uploaded two pictures from Bussard's patent for use in a future section about him... - Omegatron July 2, 2005 01:26 (UTC)
Help! I tried to edit a small part of the article, to add a little bit of text, and an error message occurred, after which, when the edit was accepted, the whole article was replaced! That was not my intention! Somebody please revert!
Could the fusor be used to provide neutrons for fission and produce power without a chain reaction and produce net power? -- Gbleem 13:54, 23 June 2006 (UTC)
Yes. The fusor's only commercial use so far is as a neutron source. I'm doing a three year long research project for high school on such a subject, although not necessarily for inducing a fission reaction. Such a use is certainly within reason. -- Liambowen 03:04, 18 July 2006 (UTC)
Strongly For -- Though there have been a few differing incarnations of IEC over the years (usually one variation per research group), to date they all have similar fusion rates for a given current and frankly there is no reason to believe any of them are particularly different. Fusor should redirect to IEC, and gridded IEC (Fusors), penning traps etc should have their own sections. -- Rpf 13:00, 23 November 2006 (UTC)
I've heard of three devices; the IXL, EXL, and polywell types. Are all of these considered "fusors", or only the first? We either need to merge them all into one article or move the stuff that refers to non-fusors into the IEC article and vice versa. I think a merge is probably best. — Omegatron 15:52, 23 November 2006 (UTC)
Strongly against -- The devices vary greatly in design and considerations. Each has their own individual history. There are many designs. Consequently, you'll either have a monstrous article, or have to cut valuable detail. What you're proposing is like merging mice, rats, gerbils, etc into "Rodent" because they're similar.
The acronym IEC, apparently meaning "inertial-electrostatic confinement," should be defined in each article before it is used there. —Preceding unsigned comment added by 98.197.236.18 ( talk) 05:10, 16 March 2011 (UTC)
I have strong reservations about including the following statement:
In the reference given, this is the only line in 258 pages that so much as mentions recirculating power. The author does not even provide a reference to more detailed work, much less justify the statement himself. I don't remember the details of Rider's derivation, but I believe it was a lower limit that did not require an exact calculation of a particular distribution. If this is the only verifiable criticism we have of Rider's work, then I think we should leave it out altogether. At the very least it must be rephrased to make it clear that it is one voice, not a scientific consensus. -- Art Carlson 14:51, 23 November 2006 (UTC)
Is Rider's paper really applicable? As it stands, only nuclei are being accelerated by the grid -- not electrons. There are electrons in the grid, but that's hardly what he's talking about. In an "ideal" fusor, the electrons are completely ignored by the fusing ions. -- Rei 20:45, 28 November 2006 (UTC)
Rie, your argument appears to be based on two points; 1) that the issue of concern is Bremsstrahlung losses, and 2) that Ryder's critque doesn't apply because it's non-quasineutral. However, you haven't offered any evidence to actually support either claim. Quite the opposite, at the start of the thread you question whether not the Fusor really is quasineutral, and then dance around the point with these "ideal fusor" confusions. Nor do you ever address the question of whether or not the Bremsstrahlung losses could be calculated without the quasineutral assumption, yet this is a hidden requirement in your line of reasoning.
To answer your very first question, "Is Rider's paper really applicable?", the answer is an unqualified "yes". The paper is called "A General Critique of Inertial-Eletrostatic Confinement Fusion Systems". The paper addresses both the Fusor and the Bussard devices directly, with diagrams. Of course the later context suggests you're really asking whether or not it applies due to some sort of "mistake" in the calculators due to the quasineutral assumption. However if you examine the Spacial Profiles area of the paper, you will note that he addresses this issue directly, and shows mechanisms for electron mixing. Yet you recently stated "As the paper is about quasineutral plasmas". The paper is not "about quasineutral plasmas", and mentions them only in a theoretical section before directly addressing the problem in the lengthy discussion that follows. I cannot help but ask you the same question Art did, have you done your homework?
Based on what I have seen so far I will be inclined to revert any removal of Ryder's work based on these arguments. If you have a real point-by-point argument that covers these issues, I'm all ears. But in the meantime, removing material based on nothing more than the fact that Art hasn't replied yet (which is precisely the justification you offer above) strikes me as a breach of good-faith editing. Maury 23:12, 30 November 2006 (UTC)
← (My mistake, I meant 4.1.7.) A "spherical ion focusing system" sounds like IEC. Ref. 85 specifically mentions IEC ("infinite Brillouin ratio", "magnetic field vanishes everywhere", last page), and 86/87 certainly deal with IEC. "Dense fusion core", "unrealistically high fields"; it sounds like IEC to me. He's ruling it out based on real-world constraints. I guess this is the crux of the matter. We're talking about real fusors, not perfect ones. Do you agree that Rider's conclusions apply to IEC under current technology? Would you be satisfied if we made that distinction?
Let me also take a different tack. Rider specifically says that his results in "Fundamental limitations" rule out any kind of IEC breakeven. He's the one making the claim. It certainly meets WP:V. According to WP:NPOV, we put it in. If someone doesn't agree, they write something that meets V and we put it in. - mak o 02:14, 3 December 2006 (UTC)
The fusion reactor that he's looking for money for is obviously a decendant of the Fusor. The ions are still confined using electrostatic confinement but the light electrons are now confined using a magnetic field rather than the grid. It's a thousand times easier to confine electrons than it is to directly confine the ions because of the mass difference so even when the electrons are thrown out a near lightspeed they can be captured by the magnetic field and routed back into the 'core'. With an overabundance of electrons confined in the 'core' the ions don't really "want" to leave (ie electostatic confinement) so you get a ball of plasma rather than a 'star' as the ions evacuate.
There will of course still be large numbers of electrons lost, anything pointy or even just metal will appear to suck them right out but from the video it appear these losses can be kept down low enough to be replenished easily. The result; reaction rate going up at the SEVENTH POWER of the reactor size is definitly worthwhile!
So I think this should be added to this page in a more explicit manner but I can't think of a good way to do it without removing half the 'this cannot be used for fusion' parts.
86.16.135.53 08:55, 10 December 2006 (UTC)
I've added three {{fact}} for bold claims without sources given.
Pjacobi 08:24, 20 December 2006 (UTC)
My concern here is that some of these issues seem so minor that questioning them seems pendantic. I would be equally confused by a post suggesting the article on "bicycle" should be removed because it contains the unreferenced claim that Trek made a bike called the 5000. Whether or not there is a bike called the 5000 has no effect on the reality of bicycles as a whole. This example might seem trite, yet it appears that this is the logic being used to suggest the deletion of the German version of the fusor article, unless I'm seriously misunderstanding your point (which is certainly possible).
I will adress your points directly:
(1) seems more that well supported. But the real question is why do you need a better one? Do you really doubt that DASA might have provided some finding to a university researcher for some small-scale fusor research? You tagged it and called it a "bold" claim, and I am trying to understand what you feel is so bold. (2) who cares? If you don't think this claim isn't supported enough, remove it. It doesn't effect the article as a whole. (3) are you asking whether or not mainstream scientists "believe" in the fusor? If that is the question, then the answer is "yes" and it rates "mainstream". (4) well obviously yes. TEEN GOES NUCLEAR If you have some more stringent definition of what you mean here, you'll have to more clearly state it. (5) I can't read German very well though, but the "calculation" you mention appears to be one persons back-of-the-envelop musings. If you can translate it into English I'd appreciate it.
I have a question in return though, because I am still thinking much of my confusion is a language issue. So let me try to make this succinct. Pjacobi, do you personally feel that the fusor is not capable of producing limited amounts of fusion and the neutrons that result from them? IE, do you feel that the fusor is basically a scam? Please be clear on this; after two messages I am more confused than ever about your position. If you do doubt the existence of fusion events in the fusor, can you explain why? Is it, as you seem to suggest, due to that single post on the German wiki?
Maury 22:47, 21 December 2006 (UTC)
I just got an e-mail from George H.Miley. He confirmed that DASA was indeed funding part of his research and were indeed planning on using it for a commercial fusion source. They eventually decided not to pursuit it, but George continues to working field. He had heard that some of the DASA people left, notably John Sved, but had not heard of NSD. I consider this to be more than enough confirmation of the story. Maury 01:11, 27 December 2006 (UTC)
Here's an amateur project by a high school student. According to this article, it does not produce net power output, but it is a true fusion reactor of the Farnsworth type. Have fun adding it. -- 205.201.141.146 18:10, 16 February 2007 (UTC)
Demining#Nuclear_detection says "A better neutron source is to use a sealed tube electrostatic D-T neutron generation tube". Is this a fusor? — Omegatron 05:08, 13 August 2007 (UTC)
IEEE Spectrum 03.09 (March 2009) issue Pages 20-21 by Paul Wallich, feature title: "hands on" (lower cased), article title "Fusion on a Budget", describes the Fusor.
Hey guys, ETW fusors are a misnomer. They only modeled these machines. They never built one. Here is their original paper: William, Elmore C. "On the Inertial-Electrostatic Confinement of a Plasma." Physics of Fluids ser. 2 (1959): 239-46. Web. I think we need to somewhat disconnect the ETW design from the fusor and shift the article to fusors being built by amateurs and professionals today. These are all Hirsch machines, but we need to clear up that confusion as well. A Fusor is a negative cage inside a positive cage in a vacuum chamber. That is what is being built around the world. The path to this machine is less important, compared with information about the machine that is working now.
Taylor Wilson is the most well know amateur fusioneer. He did win a science fair for his construction of a fusor, he was on CBS news (3/30/2013) for the work and he did present this to the president at an event at the white house. So why has his photo been taken down from the amateur fusor section of this page? — Preceding unsigned comment added by 69.205.70.3 ( talk) 14:10, 13 August 2013 (UTC)
This one might be interesting enough to add, Conrad Farnsworth. Here's his story: http://trib.com/lifestyles/home-and-garden/teen-makes-nuclear-reactor-in-dad-s-shed/article_e9576aa3-9df4-550a-9778-29c4843104ed.html AE7EC ( talk) 02:59, 11 January 2014 (UTC)
Look, there are plenty of people who are working on fusors. But, this wikipedia article should limit itself to amateurs who have actually done fusion, actually detected neutrons. This is still not a small list of people (somewhere in the region of 75, or higher) and it is also a bit dicey, since these people are often self-reporting. Richard Hull maintains a list and he places rules, there are different hoops you have to get through, first vacuum, first glow and first nuetrons, ect... and the folks have to demonstrate progress along this path, to move forward. Amatuers should be listed if they get covered by the local news, or win a science fair, or a win a well known science scholarship, because they detected neutrons created by fusion. — Preceding unsigned comment added by WikiHelper2134 ( talk • contribs) 15:05, 28 January 2014 (UTC)
The article has a glaring omission by not describing the safety issues concerned with the building and operation of a Fusor. In addition to potentially-lethal levels of high-voltage electricity, there are issues concerning x-ray and ultra-violet radiation exposure when a unit is operated at high neutron-flux levels.
A simple search reveals that to date there are more than TWELVE HUNDRED posts that invoke the word “safety.” What is interesting is that, near as I can tell, there is no “FAQ” set that specifically addresses the safety considerations that should be taken in to account when building and operating one of these things.
Paul Schatzkin, FUSOR.NET, TAG ARCHIVES: SAFETY, [7].
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After reading the material in the Talk section on Plasma Physics and in other sections contributed by Art Carlson (which do an excellent job at de-bunking this body of work), I would seriously suggest that this whole article on Fusors and the like be downgraded in importance and perhaps should NOT be part of the Physics Portal. The article is valid in its own right as a historical account in Inventions. The article cites many contentious and dubious sources. In my opinion, this can be lumped with "Cold Fusion" and other dubious science. MxBuck ( talk) 00:47, 20 October 2019 (UTC)