Stable plasma configurations in a cylindrical magnetron discharge

Transition between different plasma configurations is studied in a system with negative biased cylindrical target in crossed E×B fields. It was found that the diffuse plasma torus formed around the cylindrical target in relatively small magnetic field (0.02T on target surface) changes the shape with magnetic field to form a thin disk with a width lower than 1cm when target voltage is less than −400V. The target current decreases sharply when the magnetic field reaches some critical value. When the target voltage exceeds 400V, the target current increases with the magnetic field and the plasma has always toroidal shape. The plasma behavior can be understood taking in account the interaction of the drift currents and the magnetic field.