Plasma state transition originating from local production of massive negative ions.

A dynamic evolution of plasma structures and its associated state transition due to local production of massive negative ions are investigated by the particle-in-cell simulation which is based on an experimental configuration of an open plasma system (Q machine). Two different states, a stationary state and a dynamic state, are achieved depending on the production rate of massive negative ions. The plasma is stationary for a low production rate, while solitary pulses and fluctuations are spontaneously excited and the plasma state is unstable for a high production rate.

Pair-ion plasma generation using fullerenes.

We have developed a novel method for generating pure pair plasma which consists of positive- and negative-charged particles with an equal mass. The pair-ion plasma without electrons is generated using fullerene as an ion source through the processes of hollow-electron-beam impact ionization, electron attachment, preferential radial diffusion of ions, and resultant electron separation in an axial magnetic field. Basic characteristics of this plasma are discussed in terms of the differences from ordinary electron-ion plasmas, such as a phenomenon in the absence of sheath and potential structure formation.