Lif Measurements and Modeling of Magnetron and Filament Discharges.

Sub-Doppler laser-induced fluorescence (LIF) was used to measure ion velocity distributions in both multidipole filament and sputtering magnetron discharges. A model of LIF was developed and tested to deduce a method for finding the optimum laser intensity for these measurements. Multidipole filament discharges are used for thin film deposition and etching, for basic plasma physics research, and as a source for neutral-beam heating of fusion plasmas. It was found that the ions are at room temperature over a wide range of pressures, discharge currents, and voltages. These results stand in contrast to the "anomalously" high ion temperatures reported by researchers using electrostatic analyzers to measure the ion energy. It was also found that under most conditions, the excited-state ion density scales linearly with both the discharge current and the electron density. Sputtering magnetron discharges are used for thin film deposition and etching. In this discharge, it was found that the radial profiles of the excited-state ion density and the electron density are peaked in the electron trap. The radial and azimuthal ion drifts were found to be unmeasurably small. Outside the trap, the random ion energies for the azimuthal and radial components were at room temperature. Inside the trap, the random energy for the azimuthal component had a peak to 0.32 eV, while for the radial component it had a peak of 0.13 eV. To explain these results, a model of ion transport in the magnetron was developed. The model was implemented with a single particle Monte Carlo simulation. It was found that the dc electric field and ion-neutral collisions play major roles in the dynamics of the ions, but that the turbulent electric field does not. The simulation successfully predicted: the etch track shape, ion transit time, radial profile of ion density, azimuthal drift velocity, and random ion energy for the radial velocity component, but not the radial drift velocity or the azimuthal ion energy. The simulation also predicted the energy, angle, and spatial distribution of ion impact on the electrodes which can be used as aids to improve the design of magnetrons.