Sheath development around a high-voltage cathode

摘要: A secondary electron emission-capacitive probe has been used to explore the dynamic behaviour of sheath at high voltages in a glow discharge plasma (ni approximately 1010 cm-3 N2+, T3 8 eV) generated by inductively coupled RF power ( 300 W 12-13 MHz). When negative potential is applied cathode expands rapidly but comes steady-state position within few microseconds. The distribution then remains stable throughout high-voltage pulse as long ionization rate outside region sufficient replace ions lost cathode. Around sphere, this equilibrium can be described conventional theories Child-Langmuir sheath. Previous experimental and theoretical investigations evolution cathodic are reviewed light these results which significantly different from recently reported measurements hot-filament microwave multidipole discharges. It concluded that 'self-bias' target (which exists before application voltage) surrounding influence time-scale on equilibrium.