Abstract Details

icc2006.pdf2006-02-20 15:18:14Jason Kremer

Electron plasma equilibria in the CNT stellarator: First results

Author: Jason P Kremer
Submitted: 2005-12-21 12:18:04

Co-authors: T. Sunn Pedersen, Q. Marksteiner, R. G. Lefrancois, J. Berkery

Contact Info:
Columbia University
500 West 120th Strett Room 200
New York, NY   10027

Abstract Text:
CNT is a small (R~0.3 m), university scale, ultra-low aspect ratio (A~1.9) stellarator. CNT was designed for the study of non-neutral, partly neutralized, and anti-matter plasmas. A major goal of the experiment is to aid in the understanding of how large electric fields affect plasma equilibrium, stability and confinement in magnetic surface configurations.

Electron plasmas are presently being studied in CNT. These plasmas are created by placing a negatively biased, heated tungsten filament near the magnetic axis. The plasmas are diagnosed using similar filaments as emitting probes. Macroscopically stable equilibria of these plasmas have been observed. Electron confinement times are ~20 ms limited by the presence of bulk insulating materials in the confining region. Studies of how the confinement time scales with magnetic field strength, neutral pressure, emitter bias, and the presence of insulating materials have been conducted. The ion fraction for these electron plasmas has been measured and found to scale linearly with neutral pressure. The degree of ionization is therefore an easily controlled parameter. For the equilibrium studies presented, the ion fraction is on the order of 1%. Temperature, density, and potential profiles and their dependence on magnetic field strength, neutral pressure, and electron emitter bias are now being measured. Temperature and density measurement results indicate that the plasma criterion (many Debye lengths in the device) has been satisfied. The measurement methods and results of these experiments will be presented in detail.

Characterization: A5,E10

If given a poster, please place this poster as number 1 in the CNT posters and T. Sunn Pedersen's poster as number 2.

The University of Texas at Austin

Innovative Confinement Concepts Workshop
February 13-16, 2006
Austin, Texas

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