Low-power radio-frequency excitation as a plasma source in a Penning-Malmberg trap : A systematic study

A novel method was experimentally demonstrated to produce a low-density electron plasma in a Penning-Malmberg trap, exploiting the static electric and magnetic confinement fields together with a periodic excitation with amplitudes as low as 0.5-5 V and frequencies in the MHz range. This unusual technique proved to be applicable as a replacement for conventional electron sources in Penning devices and presents interesting aspects both in terms of basic science and technological applications. Nevertheless, the experimental observations demonstrate the high sensitivity of plasma features of interest (charge, mean density and density distribution) to the experimental conditions, namely trap configuration and excitation parameters, and as a consequence clear trends have not been identified so far. We present an experimental campaign of measurements where several parameters were systematically changed leading to a better assessment of the plasma production mechanism and to the identification of common trends.