Plasma flow from vacuum surface flashover initiated by 70-kV 20-ns pulses

Abstract

Abstract In this work we study plasma beams generated by vacuum surface flashover discharge. We measured ionic current, velocity of ions at values of discharge current 2.8 kA and 5.5 kA for polymethylmethacrylate (PMMA), polytetrafluorethylene (PTFE) and polyethylene (PE). The aim of the work is to compare parameters of particle flows at different values of discharge current and unchanged voltage. We used generators with coaxial and disk-shaped glycerol-filled pulse-forming lines. Maximum voltage is 70 kV; voltage pulse duration is 20 ns; width of a current pulse first half wave is 30 ns. Average velocity of the ions for all materials is within the range ∼ 100−150 km/s and doesn’t change significantly as the current increases from 2.8 kA to 5.5 kA. Ion current of the beam increase approximately linearly at higher discharge current. We estimate the density of electrons in plasma as a function of distance from the discharge. The applicability of this type of discharge for creating plasma for neutralizing high-power ion beams in inertial confinement fusion facilities is discussed.