[Ivy Matt]

It’s not the non-Lucasfilm swooshing sounds I like. But, yeah, I suppose it would be a lot cheaper to just buy neon lights. Or make your own plasma toys…

[Ivy Matt]

There’s a topic on this subject here. I’d read about thunderstorms generating gamma ray flashes before, but this is the first I’ve heard about them generating antimatter.

[Ivy Matt]

Unfortunately, more recently they’d been having problems with exploding spark plugs or something like that.

See here, for example.

[Ivy Matt]

Lerner wrote: we … have had the repeatability we need since the end of December.

Now that is good news indeed. I hope you’ve seen the last of the mechanical difficulties.

[Ivy Matt]

Ivy Matt wrote: So, presumably the information on the p-B11 fusion reaction was obtained by bombarding a boron-11 target with accelerated protons, and this was done back in the early ’70s.

Half right, half wrong. I was off by forty years.

Documentation of p-B11 fusion. See especially page 240.

Documentation of 8.7 MeV. See especially page 290.

Lerner wrote: It actually is easy and fun to look up the answers to these questions on the web—reaction rates and all are easy to find. I hope people on this forum will do that.

Well, I’ll vouch for the fun part, at least. Historical research is right up my alley. I spent much of Friday night and Saturday morning searching and reading about George H. Miley and UIUC; Francis K. McGowan and the Nuclear Data Tables; Oak Ridge National Laboratories’ experiments during the 1950s; and finally Cockcroft and Walton, Rutherford and Oliphant, Kirchner, Dees and Gilbert, and others “splitting the atom” in the 1930s. I hadn’t realized that phrase originally referred to nuclei with atomic weights less than iron.

Heres more historical background for those interested:

CERN Courier article on Cockcroft.

Cockcroft’s Nobel Lecture.

Walton’s Nobel Lecture.

[Ivy Matt]

I had been under the impression that nobody had achieved hydrogen-boron fusion before, but I was wrong about that, as clearly shown in Observation of neutronless fusion reactions in picosecond laser plasmas (2005). I haven’t been able to find much on the history of hydrogen-boron fusion, but from what little I have been able to find, it appears that the seminal paper on the subject was Fusion cross sections and reactivities (1974), of which George H. Miley was one of three authors. It is not available for free, but can be ordered from the National Technical Information Service for $40 on microfiche or $60 print-on-demand. However, without spending that much money, the Office of Science and Technology’s Energy Citation Database helpfully gives “BORON 11 TARGET” as one of the subjects of the paper. So, presumably the information on the p-B11 fusion reaction was obtained by bombarding a boron-11 target with accelerated protons, and this was done back in the early ’70s.

I’m not quite sure I understand your second question. Fusion occurs between unbound atomic nuclei (i.e. ions), not electrons. The products of the p-B11 fusion reaction are three helium-4 nuclei/ions, also known as alpha particles. If you’re referring to the electron beam produced by the plasmoid in a DPF, I’m not aware of any plasma focus device that has used hydrogen and boron in its fill gas so far, and I presume FF-1 would be the first.

[Ivy Matt]

I’m guessing that’s a reference to this, from Advances towards pB11 Fusion with the Dense Plasma Focus (Lerner & Terry):

To see what the consequences of the magnetic field effect are for DPF functioning, we
first use a theoretical model of DPF functioning that can predict conditions in the plasmoid,
given initial conditions of the device. As described by Lerner [12], and Lerner and Peratt
[13], the DPF process can be described quantitatively using only a few basic assumptions.
Using the formulae derived there, Lerner [1] showed that the particle density increases with μ
and z as well as with I, and decreases with increasing r. Physically this is a direct result of the
greater compression ratio that occurs with heavier gases, as is clear from the above relations.
Thus the crucial plasma parameter nτ improves with heavier gases.

I have a question about the best shot. According to the recent update, it was on September 29. However, according to fig. 1 in the same update, it’s shot 9301002. Both give the average ion energy as between 160 and 220 keV. Now, in the update of October 6, 2010, the best shot was shot 93002, which achieved an average ion energy of 143 keV. I presume they are the same shot, so what changed?

[Ivy Matt]

Would this update be for November, December, or both months?

[Ivy Matt]

Pick your poison:

Amazon

Barnes & Noble

Smashwords

[Ivy Matt]

I’m not a scientist either, but my understanding is that the beams are produced by strong magnetic fields in the plasmoid. As a plasma consists of unbound positive ions and negative electrons, the ions will exit the plasmoid in one direction (“outward”) while the electrons will (theoretically: see the discussion above) exit the plasmoid in the opposite direction (“inward”). This happens independently of whether or not any fusion reactions take place. Any neutral particles and electromagnetic rays will radiate in all directions, as they are not affected by the magnetic fields.

Note that the concentrated ion beam is a result of the plasma focus design. In a Polywell fusion reactor, for example, the alpha particles would radiate in all directions.

[Ivy Matt]

CCFE is the United Kingdom’s fusion research program. It runs JET (Joint European Torus) and MAST (Mega Ampere Spherical Tokamak). JET achieved about 0.7 Q in 1997 using D-T fuel.

[Ivy Matt]

Rather helpful and, if I read it correctly, it shows how the plasma focus idea was developed from the earlier Z-pinch, something I was unclear on before.

This caught my attention on page 55 (possibly because it was in orange type): “neutron yields are non-thermonuclear in origin”.

What does that mean? It’s my understanding that the word “thermonuclear” simply means “having to do with nuclear fusion” and not necessarily anything to do with Maxwellian distribution. Does this mean the plasma focus device doesn’t produce fusion neutrons? Given past controversies such as ZETA, cold fusion, and sonofusion, I’m aware of the importance of determining whether detected neutrons are indeed from a known fusion reaction, and I would hope everyone currently involved in fusion research is as well. However, on page 67 we have this: “Fusion neutron yield Yn : 10^6 for PF400-J to 10^11 for PF1000.” So I’m a bit confused.

[Ivy Matt]

ITER has hit funding snags before, but I’m a bit concerned about the fallout should it hit a show-stopper. Possible headline: “The dream of fusion is over”. If that becomes the narrative, investors may find it more difficult to justify risking their money on alternative fusion projects.

I’m generally content with things as they are: civilian government funding for big projects like ITER and NIF, and for university research; military funding for skunkworks projects like Polywell; private funding for private alternative projects like LPPX and Tri Alpha. I’d like to see more private investors take up the slack from government funding for fusion projects, but that probably won’t happen until fusion becomes something more than interesting physics. Where is the AT&T Bell Labs, Xerox PARC, or IBM Almaden Research Center of the fusion world?

[Ivy Matt]

Rezwan wrote: The December report is not out yet. I suspect Eric would prefer to go to quarterly reports rather than monthly. LPP is short-handed enough as it is for the experiments, and writing reports every month eats up Eric’s time and slows things down.

Ach, no! Does Eric write them himself? I thought Aaron wrote them. I might be open to bimonthly (as in bimestrial) reports, but quarterly? Leave that to the Polywell folks. ;-P

Aeronaut wrote: So a great stocking stuffer may be to hire one or two part-time interns majoring in a mix of web journalism and physics, if I understand the situation right. What would that be likely to add to the quarterly budget?

How about nothing? Some people would probably be willing to write the reports for free. 🙂

[Ivy Matt]

Warwick: I’m not sure I’d call it an urban legend. I might call it Buddhist/Hindu propaganda, but I can understand why they would want to defend a symbol that has had religious significance to them for a couple thousand years. And the Nazis did standardize on a right-facing swastika, so there is a kernel of truth to the myth. However, I doubt that the Nazis chose the swastika, right-facing or not, because it signified evil to them.

Rezwan: The pentagram can have various meanings, but in Satanism it’s generally inverted. At any rate, it wasn’t the flags of Morocco and Ethiopia I was thinking of.

Brian: That does seem to be the conventional orientation for the depiction of a series of events.

[Author]

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