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In this work the kinetics of macroparticle charging in the rarified part of the arc plasma jet are studied. The sheath in the vicinity of the macroparticle is collisionless and the problem with different Debye length to macroparticle radius ratio is analyzed. Maxwellian velocity distribution functions with different temperatures for the electrons and ions in an arbitrary ratio are allowed in the model. The influence of the plasma drift velocity on the macroparticle charging is discussed.

Heat transfer to a thermally isolated graphite anode in a long duration vacuum arc was investigated. Anode bulk temperatures were measured as a function of time using two high temperature thermocouples. The anode surface temperature was optically determined. Surface temperatures of 2300 K were obtained in a 340 A arc. A 1D non-linear heat flow model for the anode was developed. A solution was obtained using a dynamic numerical method and the effective anode potential was determined to be approximately 6 V.

The influence of the Buneman instability on the parameters of a current carrying plasma is investigated. By using the quasi-linear approximation the analytical expressions which connect the plasma parameter changes and the turbulent electrical conductivity with the energy of the unstable electrostatic field fluctuations were obtained. The latter is expressed by the plasma supercritically. The experimental data of the arc discharge in an extended gap are analyzed. It is shown that the changes of the electron temperature and potential drop can be explained by this instability.

The cathode spot vacuum arc produces a jet of highly ionized plasma plus a spray of liquid droplets, both consisting of cathode material. The droplets are filtered from the plasma by passing the plasma through a curved, magnetized duct. A radial magnetic field may be applied to the face of the cathode to rotate and distribute the cathode spots in order to obtain even erosion and avoid local overheating. The choice of axial magnetic field strength in the vicinity of the cathode is a compromise between a relatively high field desired to collimate a large fraction of the plasma flux, and the need to collect a substantial fraction of the plasma at the anode in order to reduce arc voltage and insure arc stability. The transmission of the filter duct increases with magnetic field strength until a saturation value is reached. Entrainment of the droplets in the plasma jet can decrease the effectiveness of the filter at high plasma flux. Semiconducting thin films of amorphous silicon were prepared using cathodes of heavily B-doped Si. Arcs of 35-A current produced a deposition rate of 10 /spl Aring//s. The electrical conductivity of the films was similar to conventional a-Si:H films deposited by conventional Silane based PACVD at high temperatures, but had a higher room-temperature conductivity. Transparent conducting films of Sn-O were deposited at rates of up to 100 /spl Aring//s using 160-A arcs on a Sn cathode while injecting O/sub 2/ gas in the vicinity of the substrate. Adjustment of the O content is critical for optimizing conductivity, and complicated by pumping effects of the arc. Optimal conductivity was achieved at an oxygen pressure of 6 mtorr. Conductivities equal to the best reported to date were achieved by subjecting the room-temperature deposited films to a 30-s rapid thermal annealing at 350/spl deg/C. Both the deposited and annealed films are amorphous. The deposition rates achieved by the filtered vacuum arc technique for these semiconductor films are an order of magnitude greater than achieved with conventional methods, while the conductivities are equivalent or better.