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Title: Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field

Abstract

In this paper, two-dimensional electron density measurements are made in a magnetic ring cusp discharge using laser collisional induced fluorescence. The magnet rings are isolated from the anode structure such that they can be biased independently in order to modulate electron flows through the magnetic cusps. Electron density images are captured as a function of bias voltage in order to assess the effects of current flow through the cusp on the spatial extent of the cusp. We anticipated that for a fixed current density being funneled through the magnetic cusp, the leak width would necessarily increase. Unexpectedly, the leak width, as measured by LCIF images, does not increase. This suggests that the current density is not constant, and that possibly either electrons are being heated or additional ionization events are occurring within the cusp. Spatially resolving electron temperature would be needed to determine if electrons are being heated within the cusp. Finally, we also observe breakdown of the anode magnetosheath and formation of anode spots at high bias voltage.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]
  1. Univ. of Michigan, Ann Arbor, MI (United States). Nuclear Engineering and Radiological Sciences
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Workforce Development for Teachers and Scientists (WDTS)
OSTI Identifier:
1474090
Report Number(s):
SAND-2018-10182J
Journal ID: ISSN 1361-6595; 667942
Grant/Contract Number:  
NA0003525; SC0014664
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Sources Science and Technology
Additional Journal Information:
Journal Volume: 27; Journal Issue: 5; Journal ID: ISSN 1361-6595
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; magnetized sheath; laser collisional induced fluorescence; anode spot; magnetic cusp

Citation Formats

Arthur, N. A., Foster, J. E., and Barnat, E. V. Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field. United States: N. p., 2018. Web. doi:10.1088/1361-6595/aac309.
Arthur, N. A., Foster, J. E., & Barnat, E. V. Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field. United States. doi:10.1088/1361-6595/aac309.
Arthur, N. A., Foster, J. E., and Barnat, E. V. Tue . "Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field". United States. doi:10.1088/1361-6595/aac309. https://www.osti.gov/servlets/purl/1474090.
@article{osti_1474090,
title = {Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field},
author = {Arthur, N. A. and Foster, J. E. and Barnat, E. V.},
abstractNote = {In this paper, two-dimensional electron density measurements are made in a magnetic ring cusp discharge using laser collisional induced fluorescence. The magnet rings are isolated from the anode structure such that they can be biased independently in order to modulate electron flows through the magnetic cusps. Electron density images are captured as a function of bias voltage in order to assess the effects of current flow through the cusp on the spatial extent of the cusp. We anticipated that for a fixed current density being funneled through the magnetic cusp, the leak width would necessarily increase. Unexpectedly, the leak width, as measured by LCIF images, does not increase. This suggests that the current density is not constant, and that possibly either electrons are being heated or additional ionization events are occurring within the cusp. Spatially resolving electron temperature would be needed to determine if electrons are being heated within the cusp. Finally, we also observe breakdown of the anode magnetosheath and formation of anode spots at high bias voltage.},
doi = {10.1088/1361-6595/aac309},
journal = {Plasma Sources Science and Technology},
number = 5,
volume = 27,
place = {United States},
year = {2018},
month = {5}
}

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