Berlin 2001 – scientific programme

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P: Plasmaphysik

P 2: Plasma Technology, Diagnostics I

P 2.6: Talk

Monday, April 2, 2001, 17:55–18:10, 2032

Investigations at a Pulsed Inductively Coupled Plasma in the GEC Reference Cell — •V. Kadetov, U. Czarnetzki, and H.F. Doebele — Institut f. Laser- und Plasmaphysik, Universitaet Essen, 45117 Essen, Germany

An inductively coupled discharge is operated in the GEC reference cell. The standard setup is modified in order to improve operation in pure hydrogen: Firstly, a double spiral antenna is used that allows operation at a lower voltage. Secondly, the antenna housing that consists of a stainless steel cylinder and a quartz window in the standard configuration is replaced by a monolithic quartz cylinder. This avoids inductive losses in the steel cylinder and sealing problems at the window. In addition, a better optical access to the discharge region close to the window is provided. Temporally and spatially resolved emission measurements at Balmer-alpha are performed with an intensified CCD-camera. In the cw-mode, the temporal variation of the emission intensity is a measure of the collisonal damping time constant of fast electrons. In the pulsed mode, the ignition phase is investigated. The transition from an initial capacitive mode to the inductive mode is observed in both the spatial distribution of the emission and in the temporal variation of the emission amplitude. Laser spectroscopic electric field measurements at the grounded counter electrode give detailed insight in the sheath dynamics and the temporal variation of the plasma potential.