Production of negative ion plasmas in a Q machine

A negative ion plasma is produced by introducing a small amount of SF, gas into a low-temperature (similar or equal to 0.2 eV) potassium plasma produced in a Q machine. The density ratio of negative to positive ions is continuously varied in the range up to more than 0.9999, where there appears a remarkable decrease in electron shielding for potentiat variations, yielding a clear effect on plasma collective phenomena. By introducing fullerene (C(60)) particles into the Q-machine plasma, we can produce a plasma including large negative C(60) ions. This ultrafine particle plasma might prove very attractive in fields of materials science.