Fusor Forums

Jason C Wells wrote:

Royce Jones wrote:Since the wall has a high positive charge the positively charged ions (protons) will be repelled away from the wall back into the plasma or ion cloud.

This is not true. Any configuration of charge will re-arrange itself to achieve the state of lowest energy, the state with zero field. When you put a single ion inside your vessel, then you won't have zero field. That ion will find a place to stick itself to the inside of your vessel. That is called sputtering.
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Here I think you are wrong. A single ion inside a conductive metal sphere ( a perfect Gauss Law setup) sees all of the charges on the sphere surface. The charge in front of it is cancelled/ nullified by the same charge behind it. When you consider the profuse charges on the sphere surrounding the test particle the charges always cancel out. The ion is in its own small universe where it effectively has no walls or interaction (electrostatically) with anything from the sphere surface outward. It doesn't matter what the charge is on the sphere- Earth ground, minus 100 Volts, or positive 100,000 volts. The NET effect on the test particle is nill. What ever inertia the test charged particle has will not be changed until it actually touches the sphere. If it has zero inertia relative to the sphere it will happily stay in one place for ever- provided you ignore external forces that can penitrate the sphere. This would include gravity , moving the sphere, but not electrostatic forces that are not destructive to the sphere. You can get picky and ask what happens if a cosmic ray hits one side of the sphere. A local temporary charge imbalance balance could occur and this would effect the floating internal charged particle until the charge spread evenly across the sphere (not instantanious). This could nudge the particle towards one wall, but this can be ignored from a theoretical perspective.

Sputtering is the impact of a particle on a surface that has sufficient energy to knoc off one or more particles from the surface. The KE of the impacting particle is transferred to surface particles- electrons, ions, atoms, globs... or even free quarks if the energy is high enough. The energy of the impacting particle is relavent, not the method that gave the particle it's KE. This could be from electrostatic acceleration, gravity, gun powder, photon pressure, gas pressure, baseball bat, etc. or any kinetic energy the particle had when it was introduced to the system.

If you do not like to think in terms of Gauss Law, instead use the implications of Faraday cages.

Dan Tibbets

I think Earnshaw's theorem applies. It will be interesting to see if it works out.

Regards,
Jason

It should be mentioned in this discussion that the idea of "pumping" an ion cloud by alternate electrostatic expansion and compression in a fusion reactor is not a new idea; it was pursued by the Los Alamos group back in the nineties as the "periodically oscillating plasma sphere" or "POPS." For details, Google Barnes and Nebel, POPS.
Also, the diagram of the linear device looks a lot like a linear electrostatic ion trap. Google Zaijfmann for a series of papers on this type of trap. Google Alex Klein and "MARBLE" for its application as a fusion device.