True, but the Polywell outside the MaGrid is + to attract the electrons into the center to create the wiffle ball in the first place.
I agree, an electron outside the magrid must see the magrid as +ve overall so that it gets pulled towards the magrid. Then the magnetic fields will channel them into the interior of the magrid.
The main problem is that if you "fire" the ions from outside, they arrive at the edge of the well with some residual velocity. This in theory will allow them to fall down the well, climb up the other side and still have that residual velocity. If they have it and are pointed at cusp, they will exit the MaGrid with increasing velocity and impact the vacuum chamber with great energy, ALL of which is lost.
Can't this problem be solved by giving the ions just enough energy and no more to get past the magrid then the -ve charge on the wiffleball will hold the ions inside the magrid?
Once the +ve ions are inside the +ve magrid they feel equal repulsive forces from all directions so the forces cancel each other out and the ions feel no net repulsion from the magrid, not so?
I've been strugling with this . If the ions enter the magrid through a cusp with some residual velocity, wether the magrid has some positive charge on the inside or not (through induction from the excess electrons within the magrid), the ions will accelerate to the center, then decelerate to reach the same height when next it finds a cusp, which in isolation would mean the ion reaches above the magrid and is then repelled to the wall if the magrid has a positive charge. If the magrid is grounded, the ion would not be accelerated to the vessel wall, but would it see the internal negative charge? If it is attracted to the grounded magnetically shielded magrid there may be some recircultion effect on the ions in addition to the electrons. This effect depends on Faraday cage/ Gauss's law conciderations, potential on the magrid, electron guns, ion guns(?), and vessel wall potential, etc, etc. which in my mind degenerates into confusing circular arguments.
I guess based on hear say that the magnetic confinement of the ions is ~ 1000 passes (based on what Dr Nebel said about alpha particles), and the electrostatic confinement increases this to ~ 100 thousand or more for the lower energy fuel ions. I'm guessing that the key may be that the ions have a lower average speed than the injected speed due to inefficiencies- scattering (loss of pure radial motions). ie- some scattering/ thermalization may be good within limits. You would be losing the high end tail (those ions that maintain thier original radial velocity or are upscattered. The recirculating electrons (traveling bothways in the cusps) and sheaths complicate the situation, and I'm having enough problems trying to follow the 'simple' initail conditions. Then throw in the effects of the curved magnetic surfaces, the ion gyrordius inside the cusps, any other number of considerations and my vision dims even more.
Consider an example of my rambling speculations- the space between the magnets. The spacing allows for the electron gyroradius to clear the magnets in the cusps, but the ions have a larger gyroradius, Near the top of the ions potential well, they may actually hit the magnets bordering the cusps (or at least come very close so that the induced positive charge (from the excess internal electrons) repells them) so that they fall back into the Wiffleball (with a minimum of waste heat transferred to the magrid casing). This would serve two purposes. One- decrease the charged particls escaping to the outside and contributing to arcing, and two- reseting the effective potential well peak for those ions so that it is now slightly below the midpoint of the magrid. But, what would that do to the high energy fusion ions trying to get through the cusp...?
[EDIT] For that matter, what would it do to the original ions being injected?
To error is human... and I'm very human.