The IEF concept was revived by Bussard (1985) who proposed replacing the solid wire grid with a cloud of electrons injected from outside the larger sphere. In this way, the negative potential of the inner "accelerating grid" could be controlled by the energy of electrons injected into the plasma and the electron cloud would be "transparent" to the ions streaming through it.

It is also worth noting that while the inner grid (solid or electron cloud) would be biased to 50-100 kV to maximize the reaction rates, these fields are not strong enough to hold the reaction products from the fusion reactions which are normally released at the 1-10 MeV level. Such particles will stream out through the "grids" and be converted directly to electricity via electrostatic plates far outside the accelerating structures. Efficiencies of converting thermal energy to electricity ranging from ~ 60-80% are possible.

The reason IEF is more efficient than MCF for high temperature plasmas has to do with the fact that it is the high energy "tail" of the Maxwellian distribution of thermalized plasmas that produces most of the fusion in a Tokamak for example.