TheRadicalModerate wrote:So I'm missing how you get electrons to flow from the magrid to the collector.
Hook them both to ground. Whichever one is at ground potential (pick one for now, rather than trying to strike a balance) will just dump current. Whichever one is at a couple of megavolts relative to ground will have to be hooked up through a load (ie: the power grid).
I also may be confused by the terms "electron uptake at the magrid" and "fuel electrons."
Electron uptake at the magrid is electrons that hit the grid and are sucked out. Fuel electrons are electrons from the ionized fuel. Since the fuel ions have to be at zero energy just inside the magrid, I assumed their electrons were too. There are probably multiple ways to swing this.
To my mind, the ionized electrons get pumped into the e-guns and fired into the wiffleball, which keeps things neutral.
That's why I tried to separate the electrons from fuel ionization ("fuel electrons") and the electrons used to form the wiffleball. They aren't the same; there must be more electrons in the reactor than you could have gotten from just ionizing the fuel, or else there wouldn't be a potential well.
On the other hand, with most of the electrons having matching ions (quasi-neutral), it becomes a bit funny to try to form a wiffleball, which requires the electrons to be at high energy. Maybe my picture of two electron populations at different energies was inaccurate. Perhaps we need to keep the electrons at high energies and just pump the ions in somehow... Or the wiffleball could just require a massive current to form, and then ECR of neutrals inside the magrid could produce that low-energy secondary population of electrons that equilibrates with the fusion rate...
The whole magrid+wiffleball will develop a gradually negative charge as alphas leave the system, but that charge can be drained off through a (small, low-power) current to ground (no doubt through a load).
The magrid+wiffleball is positive. That's how electron recirculation works. Perhaps beta=1+delta could be how electron losses equilibrate with fusion rate - keeping the well right on the edge of blowing out.
EDIT: Sorry, I see what you're saying. Yes, that's right - just replace "gradually negative" with "gradually less positive".
So, ultimately, you've got three different electrodes, all with negative charge: the magrid, the trap grid, and the collector. Then you've got a powerful positive current radiating out through the alphas. But I don't see how you get any more current to flow than a low-energy recombination current.
Okay, I think I see. You've fundamentally misunderstood the relationship of charge and potential. (Okay, that sounded harsher than it needed to...) The space within the trap grid is at a roughly constant potential of ~2MV with respect to the collectors, due to the trap grid charge. Anything that enters or leaves that space (like the magrid equalization current) is going to have to traverse that potential difference. The magrid perturbs the potential distribution, but not substantially (couple of %). So either you ground the magrid and have the trap grid be at a slightly lower potential and the collector at a massively higher potential (the magrid equalization current has to pass this too, net result ~0 and it's shielded from the actual gradients by the conductor it's flowing in), or you ground the collector and have the trap grid be at a massively lower potential and the magrid at a slightly higher potential than the trap grid.
Either way, one current or the other is going to be multi-megavolt, which is what we're looking for.