Helicon Wave Studies

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Helicon waves are bounded electromagnetic waves in magnetized plasmas with frequencies between the ion cyclotron frequency wci and the electron gyrofrequency wce which satisfy wciwwce and wwcewpe2. They are important because they are not limited by plasma density, and they represent a relatively inexpensive technology that can be employed in a growing list of applications which can take advantage of high plasma density. These include: large radii RF ion lasers; plasma processing; sources of multi-charged ions for accelerators; in collective plasma accelerators; ion thrusters for spacecraft; and plasma sources for basic plasma experiments. The objective of these studies is the adaption of helicon sources to the efficient production and heating of large steady-state high density plasmas (with densities of 1013cm-3 - 1014cm-3 and higher), to explore the present applications and to find new applications. Studies will include: control of the radial power deposition profile; the m = + 1 surface mode which has no density cutoff; ponderomotive effects on source; magnetohydrodynamic stability; the role of neutrals; and characteristics of pulsed sources. Experiments will build on past experience with axisymmetric mirror plasmas (e.g. ponderomotive force and rotating field antennas which allow control of azimuthal rf modes). Theory will extend previous analytic theory to higher frequencies and take advantage of extensive experience with the code ANTENA to analyze rf field data.