A novel system for studies of dc discharge in cylindrical magnetron

Abstract

In a cylindrical magnetron, the electric field is applied in the radial direction and the magnetic field in the axial direction. In this paper, we present a description of a novel construction of cylindrical magnetron developed in the University of Greifswald, FRG. The system has been designed for experimental and computer-modelling studies of the DC discharge in crossed electric and magnetic fields in cylindrical geometry. In order to approach conditions close to an infinitely long system, and hence, to enable a more precise comparison with 1-D simulations, the ratio of the vessel length to the distance between the cathode and the anode has been chosen equal to 20. Six evenly distributed coils create the axial magnetic field. The homogeneity of the magnetic field ± 0.2 % has been achieved over the whole discharge vessel length 300 mm. The system is equipped with a rotable planar Langmuir probe movable in the radial direction. Measurements of the axial dependencies of plasma parameters are enabled by positioning the Langmuir probe in one of the 5 probe ports located between each couple of coils. We present the results of preliminary measurements of the radial and axial profiles of the plasma density and the mean electron energy.

A study of the DC discharge in a cylindrical magnetron comparison of experiment and a pic model

“…This difference has been attributed to the end effects that are not taken into account in the one-dimensional model. In order to minimise the end effects, a novel experimental system has been constructed where the length/radius ratio of the discharge chamber is much higher compared to the present system [9].…”

Observation of Wave‐Like Structures in Magnetized DC Dischargein Cylindrical Symmetry in Argon

“…In our previous experimental studies we already reported the presence of fluctuations of the plasma potential in cylindrical magnetron system [4,5]. Fluctuations manifested themselves as an unwanted noise added to the Langmuir probe floating potential when measuring with the floating probe and in the increased noise of the measured current when measuring the V-A probe characteristics.…”

Modeling and Diagnostic of the Plasma of Magnetic Field Supported Discharges

“…The plasma in axial direction becomes inhomogeneous and with that also the axial components of the radial current densities to the cathode. In the last periods of the SFB 198, therefore a magnetron of a length of 30 cm with 6 magnetic coils and 5 ports for probe measurements in radial direction was used [5], [10]. Half of the cylindrical cathode was subdivided in 14 segments, which were electrically isolated of each other.…”