Magnetron discharge with azimuthally nonuniform cathode

The paper presents results of discharge characteristics studies in crossed E-H fields of a planar magnetron filled with deuterium and using different materials of the cathode-target whose secondary ion-electron emission coefficients differ essentially. It was found that both voltages at which discharge takes place and current-voltage relation (CVR) modes differ substantially for beryllium and tungsten. In the case of beryllium cathode, the discharge voltage is relatively small and varies depending on mode of operation very weakly over a wide range of condition changes. The CVR of a discharge with a tungsten cathode, on the contrary, is "classic"-the discharge voltage is considerably higher and substantially depends on external parameters. The results of magnetron discharges studies with a composite cathode incorporating sectors made of different materials are being presented as well. The authors note that an azimuthal drift in the crossed fields results in an efficient "mixing" of emission electrons knocked-on from different target materials. As a result, the discharge with such an azimuthally nonuniform cathode has a characteristic similar to that recorded for beryllium cathode. The dynamics of CVR modification was studied too. Relative re-deposition of sputtered target atoms was revealed experimentally, and a theoretical interpretation of this effect was carried out using the so-called function of virtual source of thermalized target atoms.