Most experimental fusion reactors use quasi-neutral plasma as the working substance. However, there are numerous advantages to using a non-neutral plasma:
- Ease of confinement. Pure proton gases have very long confinement times, and with special setups, can actually be confined indefinitely. Compare this to non-neutral plasmas, which have very short confinement times.
- Reduction of bremsstrahlung losses. Bremsstrahlung losses are one of the prime sources of energy loss in fusion reactors. However, according to the Larmor formula, this loss is proportional to $m^{-4}$ in toroidal setups. Just by expelling all electrons, bremsstrahlung losses can be reduced by a factor of $10^{13}$. Wouldn't it be advantageous to increase the mass of your ions as much as possible - say, by using heavier atoms and expelling all electrons?
- It seems that almost all the heating methods used for neutral plasmas can be used for non-neutral ones (microwave heating, neutral beam injection, etc.)
- Creating non-neutral plasma isn't difficult - ionizing species is not a difficult task, and the energy investment isn't too high. Furthermore, these "waste electrons" could be reused in some type of direct energy conversion scheme.
While I understand that Coulomb forces would be great, leading to increased mechanical stress, I don't see how this invalidates the technology. Many places are experimenting with non-neutral plasmas, and they seem so attractive that I don't see why they are so unpopular.