Talk-Polywell.org

I have read your assesment that (if I understand you correctly) no matter how small that trickle is, it will attract some ions, which will then attract further electrons which will result in a cascade effect of blowing a big hole through the cusp. Very Bad. We'll, maybe not quite that bad. I see it...

I love it. Why do you think the density ratio will have this value Because Bussard and Nebel both stated it does. In the face of a calculation that contradicts your intuition, the way things "seem" to you doesn't carry much weight. Shrug. I don't believe your calculation carries any more weight than...

40 kW/m^2 looks good to me, I'll take it for now. :) Since I'm the one insisting up and down the block on taking quantitative calculations seriously unless you have a good reason not to, I guess I have to accept the figure for now, too. :) Of course, the resistivity may be anomolous, but at present...

As i've mentioned before, it seems to me they will either oscillate with a period equal to the electron transit speed, or they will bunch up and form a stationary cloud. Either way, it seems like the hole is going to get pluged by a "virtual electrode." And what are the ions doing all this time? Wh...

I understand (hopefully correctly) that (1) tokamaks have problems partly because it's really hard to magnetically confine the positive ions which are massive and we have to get to a really high average temperature for some fusion to occur, (2) the polywell has the advantage of trying to magnetical...

The cusps aren't losses (recirculation). They just need to be small enough for a 1,000:1 or better density ratio. It is totally unclear both (a) how Bussard calculates losses, and (b) how he connects electron density from recirculation to the neutral density of the Paschen cruve. Heh, well, it's no...

I guess I just don't get your math. To start, what is debye length even supposed to mean when talking about a pure electron sheet. That would mean the thickness of your pure electron sheet would *decrease* with higher densities. That makes no sense to me. Then plug in the electron gyroradius. That ...

TallDave, do you have any idea how Bussard calculated electron losses and their scaling then? Classical cross field diffusion? In the Valencia paper, there's a reference to equations or programs developed at EMC for cross-field diffusion. The rest would come from metal surfaces not shielded. Bussar...

@Tom: No matter how deep the bowl is, electrons will form a trail through the cusps and out beyond the magrid. What is to keep ions from sneeking along this trail under cover of the electrons' charge? Are you suggesting that the electron distribution will form saddle points in the potential well at...

I'm confused. NRL and other sources say Spitzer resistivity is eta|| = 1.03e-2 * T^-3/2 * Z * ln_lambda [ohm-cm] but Chen says half that. I believe the value you quote is the perpendicular Spitzer resistivity. The parallel Spizter resistivity is a nearly clean factor of 2 (actually 1.96) smaller. W...

I have presented a calculation that says that the electrons punch a hole in the well seen by the ions. That is why I don't call "they don't have enough energy to get out" a satisfactory explanation. I don't see how you showed that. The polywell is symmetric and electric fields superimpose, even fie...

TallDave, do you have any idea how Bussard calculated electron losses and their scaling then? Classical cross field diffusion? I have also heard no satisfactory reason why ions loss through the cusps should not be an important channel. Because they don't have enough energy to get out and up scatter...

Art, what would stop either the electrons or the ions that sneak out from sneaking back in on the return path, and the energy lost comes back in with them. The electric charge on the magrid. If it pushes the electrons back in, then it can only pull the ions all the way out. Or do you still have the...

@choff: The problem is not ion loss per se, but the energy they take with them when they go.

@Tom: No matter how deep the bowl is, electrons will form a trail through the cusps and out beyond the magrid. What is to keep ions from sneeking along this trail under cover of the electrons' charge?

means that he ends up with a huge machine with the losses concentrated at pin prick holes. The cusps aren't losses (recirculation). They just need to be small enough for a 1,000:1 or better density ratio. It is totally unclear both (a) how Bussard calculates losses, and (b) how he connects electron...