Operation And Measurement Of Penning Discharges For Beam Plasma Experiments

To enable experiments that benchmark PiC simulations of non-linear saturation mechanisms of beam plasma interactions and that investigate mechanisms of Auroral Kilometric Radiation generation $^{1,2,3}$, a plasma column (20cm- 1m in length) is formed inside a cylindrical waveguide having a diameter $( \sim 5$ cm). This tightly constrained the dimensions allowed for the plasma source. To meet this constraint, two Penning-discharge configurations were designed. The electrons are insulated from the cylindrical anode (the waveguide) as it is linked by a magnetic field whilst the ends of the anode cylinder are closed by cathode electrodes, providing extended electron path lengths, allowing the discharge to be maintained at low pressures $( \sim 10 ^{-3}$ mB). When a bias of a few kV was applied to the anode, the discharge ignited, establishing the plasma column. Up to a few 10's mA were provided to the discharge in either a partially-modulating or continuous mode.