Aachen PK 2003 – scientific programme

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P: Plasmaphysik

P 3: Low Temperature Plasmas, Plasma Technology

P 3.6: Talk

Monday, March 17, 2003, 17:25–17:45, FO4

Plasma diffusion from a low pressure ECWR source — •Vasile Vartolomei, Hartmut Steffen, and Rainer Hippler — Department of Physics, University of Greifswald, Domstr.10a, D-17489 Greifswald

The ECWR source is an inductively coupled radio frequency discharge with some additional features. A static magnetic field is superimposed perpendicular to the RF magnetic field. The source is coupled to a diffusion chamber. They are separated by a grounded grid.

It is still not clear how the plasma parameters evolve from the source to the diffusion chamber. A Langmuir probe and an energy analyser were used to measure the plasma potential, electron temperature, plasma density and ion distribution functions along the axis of a diffusing argon plasma.

The presence of a magnetic field and a grid creates a complex situation for interpreting and modelling the results. First the complexity of the discharge has to be reduced as much as possible. The starting point of our investigations is a normal RF inductive discharge expanding into to the diffusion chamber. Step by step the degree of complexity was increased by adding the magnetic field and the grid.

In order to model the results we assume a flux conservation of the plasma drifting away from the source (spherical expansion). The plasma density and the potential are connected by Boltzman‘s relation.