@article {58925, title = {Drifting Ionization Zone in DC Magnetron Sputtering Discharges at Very Low Currents}, journal = {IEEE Transactions on Plasma Science}, volume = {42}, year = {2014}, month = {10/2014}, pages = {2578 - 2579}, abstract = {

Discharges with crossed electric and magnetic fields are known to develop instabilities that are crucial in the transport of charged particles. Sputtering magnetrons are no exception. While most recent studies focused on traveling ionization zones in high power impulse magnetron sputtering, we show here fast camera images of magnetron discharges at very low current. A single drifting ionization zone is always present, even down to the threshold current of about 10 mA.

}, issn = {0093-3813}, doi = {10.1109/TPS.2014.2334601}, author = {Andr{\'e} Anders and Pavel A Ni and Joakim Andersson} } @article {58923, title = {Drifting localization of ionization runaway: Unraveling the nature of anomalous transport in high power impulse magnetron sputtering}, journal = {Journal of Applied Physics}, volume = {111}, year = {2012}, month = {03/2012}, pages = {053304}, abstract = {

The plasma over a magnetron{\textquoteright}s erosion {\textquotedblleft}racetrack{\textquotedblright} is not azimuthally uniform but concentrated in distinct dense ionization zones which move in the E x B direction with about 10\% of the electron E x B/B2 drift velocity. The ionization zones are investigated with a gated camera working in concert with a streak camera for Al, Nb, Cu, and W targets in Ar or Kr background gas. It is found that each ionization zone has a high plasma density edge, which is the origin of a plasma-generating electron jet leaving the target zone. Each region of strong azimuthal plasma density gradient generates an azimuthal electric field, which promotes the escape of magnetized electrons and the formation of electron jets and plasma flares. The phenomena are proposed to be caused by an ionization instability where each dense plasma zone exhibits a high stopping power for drifting high energy electrons, thereby enhancing itself.

}, keywords = {Cameras, ionization, Magnetic fields, Plasma density, plasma ionization}, issn = {00218979}, doi = {10.1063/1.3692978}, author = {Andr{\'e} Anders and Pavel A Ni and Albert Rauch} }