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A cylindrically symmetric (azimuthal mode number m=0) resonant inductive (MO/RITM) radio frequency (rf) helicon wave high density plasma source is described. The source consists of an antenna and bell jar generator immersed in a diverging magnetic field. Plasma is generated in this upstream region and then is transported along the field lines into the low-field downstream processing chamber. A propagating wave is observed in the plasma with rf spatial distribution and propagation characteristics that obey the theoretical m=0 helicon wave dispersion relation. By varying the divergence of the source magnetic field, the wafer etch rate and etch uniformity can be controlled. Spatially resolved optical emission spectroscopy shows that molecular gases are almost completely dissociated near the plasma center and have a uniform radial distribution. Highly uniform plasma and neutral distributions are then produced at the wafer location, and have been used in a variety of etch applications.

The modfication of surfaces during exposure to plasma bombardment is a critical issue in the development of limiter and wall materials for fusion confinement experiments. Controlled studies of the erosion and redeposition of materials during high flux and fluence plasma exposure are now possible in the PISCES facility. PISCES is a continuously operating plasma device which has achieved hydrogen plasma densities of over 10 13 cm" 3 and electron temperatures of 5 to 24eV over large areas. Ion fluxes of 10 17 to 10 19 cm" 2 sec 1 and fluences of up to 10 23 cm* 2 have been used to bombard biased samples inserted into the plasma. The plasma parameters can be selected to produce simple sputtering, or redeposition by the ionization and recycling of the sputtered target materials. Collaborative studies on the performance of Cu and Cu-Li alloys (with ANL), stainless steel (with SNLL), and graphite (with IPP at Garching, and SNLL) have been undertaken. Surface topography modification is always observed after a sufficient fluence is achieved-The net erosion rate is significantly lower during redeposition than one would expect from classical sputtering yields. The transport and deposition of different materials by the plasma to the samples during redeposition conditions results in greatly modified surface composition and morphology. Chemical sputtering of graphite during low energy, high flux (>10 18 cm" 2 sec" 1) plasma bombardment is observed. Chemically formed hydrocarbons are relatively easily redeposited compared to sputtered carbon. The performance of these materials, the surface morphology evolution, and the characteristics of the redeposited materials are discussed.

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