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[en] The influence of the radial plasma density gradient on the dispersion of a guided helicon mode is considered. For a parabolic density profile, the conditions under which the wave frequency is proportional to the axial wavenumber squared (ω∼k_z²) are obtained.

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[en] For a classical two-dimensional one-component plasma (with a logarithmic interaction), the one-body density can be calculated exactly when the coupling constant has the special value GAMMA = 2. The behaviour of this density is studied near the wall of the circular box which encloses the system. If there is an excess charge, it concentrates near the wall. The density at the wall is related to the kinetic pressure, which differs from the thermal pressure

[en] Helicon discharges are known for their ability to produce high densities of partially ionized plasma, their efficiency arising from an unusual mechanism of rf coupling. However, the requirement of a dc magnetic field has prevented their wide acceptance in industry. The use of permanent magnets greatly simplifies helicon sources, and arrays of small sources extend the use of helicons to the processing of large substrates. An eight-tube array was designed and constructed, and its density uniformity measured in a 53x165 cm² chamber. Three innovations involved (a) the remote field of ring magnets, (b) a low-field density peak, and (c) rf power distribution. High-density plasmas uniform over large areas requires compatibility in all three areas.

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[en] The final focus of NDCX-II contains a region with quite high plasma density. We estimate here how much collisional scatter we expect from transit through this plasma. A separate question, not explored here, is how much scatter there might be off of collective fluctuations in the neutralizing plasma, including those driven by the passage of the beam.