Ion Energies in an Open-Diode Hollow Cathode Discharge

Ion energy measurements from a ¼ inch cathode were made with krypton and xenon expellants at a range of flow rates and discharge currents using an electrostatic energy analyzer mounted on axis. High energy ion content scaled strongly with discharge current and inversely with mass flow rate and molecular mass. At high current conditions for krypton and xenon peak ion energies exceeded 130eV (>17kms⁻¹) and 75eV (>10kms⁻¹) with high energy tails extending well beyond 140eV and 200eV respectively. No conclusive correlation was round with discharge noise in the form of high frequency voltage oscillations and high energy ion content.