Pulsed low frequency plasma source

An inductively coupled pulsed plasma source with an operating frequency of 29 kHz is under investigation at the Institute for Applied Physics in Frankfurt. The experimental setup consists of a series resonance circuit with a load capacitance of 12 muF and a large diameter induction coil surrounding a spherical discharge vessel. During discharge generation pulse coil currents reached a maximum value of 10 kA with current rise times of 2 kA/mus while achieving an energy coupling efficiency of 80% between the driving circuit and the plasma. Pulse power peak values reached more than 1 MW. The current rise times required for plasma initiation were measured as a function of the applied gas pressure for Argon, Hydrogen, Helium and Nitrogen. A complete discharge sequence over a period of 120 mus was documented using a fast camera system. Moreover the spectroscopic diagnostic revealed a high fraction of ionized particles and an emission spectrum in the near UV domain. Electron densities reached peak values of 10²¹ m^-3.