| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | S.A. Exarhos, Lawrence University |
| Authors: | S.A. Exarhos, Lawrence University M.R. Stoneking, Lawrence University J.W. Darrell, Lawrence University |
| Correspondent: | Click to Email |
Non-neutral plasma, or plasma made up of particles of a single sign of charge can be isolated and confined for long periods of time, permitting detailed examination. Non-neutral plasma possesses characteristics that are unique (such as a dynamic equilibrium state), while exhibiting some phenomena that are similar to neutral plasma (such as supporting the propagation of electrostatic waves). Previous work on non-neutral plasma has been conducted largely in cylindrical traps, but our toroidal trap offers the opportunity to test theoretical predictions that are not observable in cylindrical geometry. One such effect is the transport and mode damping due to a phenomenon called magnetic pumping. We report on experiments in which we excite toroidal analogs of two different so-called ‘diocotron’ (or flute-like) modes in the plasma in order to diagnose its characteristics and behavior. The frequency of the m=1 diocotron mode is proportional to the total trapped charge in the plasma. The damping of this mode has a strong dependence on magnetic field that is not presently understood, though theory suggests there is a dependence on, as yet unmeasured, plasma temperature. The frequency of the m=2 diocotron mode provides information about the average density of the plasma and its time variation, as well as its dependence on magnetic field, and other experimental control parameters. The combination of total charge and average plasma density provides a measure of plasma transport. This work is supported by National Science Foundation Grant No. PHY-0812893.