Search found 144 matches

by rnebel
Fri Aug 01, 2008 6:57 pm
Forum: Theory
Topic: Possible wiffle-ball analytical solution
Replies: 88
Views: 62934

Art: Just a thought, but I suspect that you can answer your question about electrons trapping on a flux tube analytically. Write the equation of motion of the electron in either LaGrangian or Hamiltonian form. If the vector potential of the magnetic field has any symmetry, then you should get a cons...
by rnebel
Tue Jul 29, 2008 12:08 am
Forum: Theory
Topic: What does "beta" mean?
Replies: 17
Views: 14604

The ideal gas law only rigorously applies if the distributions are thermal. In genersl, pressure is a tensor. For the nonthermal case, the pressure tensor needs to be closed kinetically ( a rather nasty sort of thing).
by rnebel
Sun Jul 27, 2008 4:54 pm
Forum: General
Topic: Suppose..
Replies: 7
Views: 5059

As Aero says, SBIRs are probably a good place to start. DOE has them as well as DOD and I expect that is true of most government agencies. Phase I SBIRS are typically $100,000 and run for 6-8 months. SBIRs are mandated by Congress and many government managers view them with disdain. They look at Pha...
by rnebel
Sun Jul 27, 2008 4:43 pm
Forum: News
Topic: Any official news as of late July 2008?
Replies: 154
Views: 92731

We have to be very careful about dealing with Congress on this. Money that gets appropriated through Congressional pressure looks like an earmark and gets labeled as pork. That kind of money can go away in a big hurry. That wouldn't serve anyone very well. Consequently, we are going through the peer...
by rnebel
Thu Jul 24, 2008 9:48 pm
Forum: Theory
Topic: Where's the beef?
Replies: 132
Views: 71109

M Simon: The alphas leave the nucleous positively charged. When they exit the device, it will become more negatively charged. However, those electrons don't necessarily come from ionization. They can come from anywhere. Blaispascal: A lot of people think that, but that's wrong. If you do that you en...
by rnebel
Thu Jul 24, 2008 8:24 pm
Forum: Theory
Topic: Where's the beef?
Replies: 132
Views: 71109

jmc:

For Polywell reactors, none of the electrons will come from ionized gas.
by rnebel
Thu Jul 24, 2008 8:19 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

Art: If electrons collide and lose all of their angular every time they cycle and all I am looking for is 10:1 convergence (at most, since we both agree that I don't need any convergence) then it seems to me that I have at most a 10% problem. If you want to claim that the collisionality is less, the...
by rnebel
Thu Jul 24, 2008 5:55 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

to jmc: I'm sure at low densities this is the case, I find it hard to believe at, say, 10^20 particles per metre cubed collissions won't create local thermal equilibrium. Which brings me to the point that I have been asking for quite a while and digging up the literature but have found no answer to....
by rnebel
Wed Jul 23, 2008 8:08 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

Art: Having those electrons reflect is exactly what you want them to do. During part of their orbit they exchange kinetic energy for potential energy, and during another part of their orbit they exchange potential energy for kinetic energy. To them the potential well (virtual cathode) looks like a p...
by rnebel
Tue Jul 22, 2008 11:55 pm
Forum: Theory
Topic: Of Line Cusps
Replies: 39
Views: 21116

1-D PIC simulations say the following:

1. Electrons leave the well at the same rate they are injected.
2. Ions can only leave if they are upscattered out of the well and have a much longer confinement time.

This is the answer you get if the ionization rate is small. There is no mass dependence.
by rnebel
Tue Jul 22, 2008 10:05 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

Let me summarize my views on this thread. 1. Art’s objections are centered on the assumption that flux surfaces are equipotential surfaces. That’s where the defocusing aberrations come from. That’s a valid assumption for l.t.e. plasmas like Tokamaks, but not IECs. Electron inertia allows gradients a...
by rnebel
Thu Jul 17, 2008 10:26 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

Jmc: To my knowledge, the Polywell is the only electrostatic machine that operates in the quasi-neutral limit. It’s possible that Lavrent’ev did some similar work to this, but I don’t know the Soviet literature very well. Consequently, I think that the polywell is the only system that has operated i...
by rnebel
Wed Jul 16, 2008 11:18 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

Art:

I just happened to stumble across the Dolan/Bussard/Krall exchange on defocusing. Dolan's original comments appear in the August 1993 edition of Fusion Technology. Bussard and Krall's response is in the March 1994 edition of Fusion Technology. The discussion should look familiar.
by rnebel
Wed Jul 16, 2008 5:24 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

[quote="Art Carlson"][quote="rnebel"]4. The idea behind inertial electrostatic confinement is that you inject electrons with directed (radial) energy into the system. These electrons then form a virtual cathode by giving up their kinectic energy to potential energy in the virtual cathode (hence the ...
by rnebel
Wed Jul 16, 2008 4:26 pm
Forum: Theory
Topic: The problem with ion convergence
Replies: 126
Views: 61274

OK. I get the idea. I agree that you quickly reach the point where you really need to do kinetic calculations. I have an idea of how I can make an analytic estimate of the interaction of annealing with lumpy equipotentials, but maybe it is better to try to make a connection to the published calculat...