Saturation of the magnetic confinement in weakly ionized plasma

Abstract

Plasma transport in magnetized discharges is a long-standing problem because it strongly depends on instabilities whose properties and influence on the plasma transport are difficult to predict. A magnetized plasma column is investigated with 2D particle-in-cell (PIC) simulations in the plane transverse to the magnetic field, at gas pressures between 3 and 12 mTorr and magnetic field intensities between 0 and 40 mT. At high magnetic field, instabilities develop and rotate in the diamagnetic drift direction. It is shown theoretically and by simulation that the magnetic field confinement is destroyed by the instability. Predictive formulas of the main parameters of the instability-enhanced plasma transport such as the edge-to-center plasma density ratio (or h factor), and the effective collision frequency are provided and successfully compared with the PIC simulations.