Long-Time Confinement of Toroidal Electron Plasmas in Proto-RT

摘要

Long-term confinement (the upper limit is set by the diffusion due to neutral collisions) of toroidal electron plasmas is achieved in a dipole magnetic field configuration of an internal conductor device by the optimization of internal potential profiles. The application of a negatively biased electrode makes possible the elimination of a potential hall inside the plasma and results in the stabilization of the diocotron instability. In the experimental parameters of the magnetic field B ～100 G and back pressure P ～ 10~(-4) Pa (～10~(-6) Torr), the obtained maximum decay time of the trapped charge (number density n_e ～ 10~(12) m~(-3)) is 200 msec, which is comparable to the classical neutral diffusion time. It is demonstrated that toroidal magnetic surface configurations have excellent confinement properties for non-neutral plasmas, and might be useful as applications for novel traps of charged particles such as anti-matters' or other multi-fluid non-neutral plasmas.