Broadband radio frequency plasma generation in a Penning-Malmberg trap

Plasma generation is observed in a cylindrical Penning–Malmberg trap in the ultra-high vacuum pressure regime for a large bandwidth of low-power radio frequency (RF) excitations. The process of plasma formation is investigated by measuring the density profiles and a simplified model is developed to characterize the electron heating mechanism. The total charge confined at equilibrium is systematically studied for RF drives in the 0.1–20 MHz range and with different geometrical configurations. With electron densities of some 106 cm−3 at least, the scheme represents an alternative source of non-neutral plasmas for Penning–Malmberg traps.