Neutral Gas Behavior During Gas Puffing in the Large Plasma Device

POSTER

Abstract

The Large Plasma Device at UCLA has been upgraded with a new large-area Lanthanum Hexaboride plasma source. To optimize performance of this source, a new gas puff system has been installed and utilized to generate quiescent, uniform, high density plasmas. In this work, we document the dynamics of neutrals in the LAPD during gas puffing experiments. We use nude Bayard-Alpert Ion Gauges placed inside the vacuum chamber at three axial locations to measure the time-dependent behavior of neutral gas pressure during puff-fueled shots under varying machine parameters. These gauges are shielded from plasma discharge light in order to prevent photocurrent pollution of the collector signal. The gauges and puff valves will be calibrated in a specialized chamber to obtain neutral particles per puff. Gauge signals are a complex combination of neutral flow caused by pressure gradients, charge exchange, recombination, and other loss mechanisms. Enhanced axial transport of neutrals is observed during plasma discharge. Neutral dynamics are key to understanding the final plasma states that are observed.

*Work supported by the US DOE and NSF, and performed at the Basic Plasma Science Facility, UCLA.

Presenters

  • Thomas Look

    • University of California, Los Angeles

Authors

  • Shruti Iyer

    • University of California, Los Angeles

  • Thomas Look

    • University of California, Los Angeles

  • Jessica Gonzalez

    • University of California, Los Angeles

  • Shreekrishna Tripathi

    • University of California, Los Angeles

  • Patrick Pribyl

    • University of California, Los Angeles

  • Troy Carter

    • University of California, Los Angeles

  • Walter N Gekelman

    • University of California, Los Angeles