Alfv\'{e}n Wave Behavior in Partially Ionized Plasmas and a Strong Density Gradient in the Hot hELicon eXperiment (HELIX)

Damping of Alfv\'{e}n waves is one of the most likely mechanisms for ion heating in the solar corona. Ion-neutral collisions have significant but poorly-understood effects on energy transfer and Alfv\'{e}n wave propagation in partially ionized plasmas, such as those found in the solar chromosphere. The neutral density in HELIX varies strongly with radius, giving access to a wide range of Alfv\'{e}n dynamics across the plasma column. The ratio of ion-cyclotron collision frequency in the solar atmosphere varies from 10-6 to 10, while in HELIX the ratio varies from about 0.02 to 0.5. With the use of a new internal wave-launching antenna close to the high-density core and a small-scale magnetic sense coil probe, the behavior of radially confined Alfv\'{e}n waves is measured and characterized in helium. These propagation measurements, along with LIF observations of the temperature and drift of a minor argon ion component in the majority helium plasma, are compared to observations in the corona.