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Title: Direct measurement of the transition from edge to core power coupling in a light-ion helicon source

Here, we present time-resolved measurements of an edge-to-core power transition in a light-ion (deuterium) helicon discharge in the form of infra-red camera imaging of a thin stainless steel target plate on the Proto-Material Exposure eXperiment device. The time-resolved images measure the two-dimensional distribution of power deposition in the helicon discharge. The discharge displays a mode transition characterized by a significant increase in the on-axis electron density and core power coupling, suppression of edge power coupling, and the formation of a fast-wave radial eigenmode. Although the self-consistent mechanism that drives this transition is not yet understood, the edge-to-core power transition displays characteristics that are consistent with the discharge entering a slow-wave anti-resonant regime. RF magnetic field measurements made across the plasma column, together with the power deposition results, provide direct evidence to support the suppression of the slow-wave in favor of core plasma production by the fast-wave in a light-ion helicon source.
Authors:
 [1] ; ORCiD logo [2] ;  [2] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [3] ;  [1]
  1. Univ. of Illinois in Urbana-Champaign, Champaign, IL (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; DEAC05- 00OR22725
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 5; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; helicon plasma; MPEX; deuterium
OSTI Identifier:
1456815
Alternate Identifier(s):
OSTI ID: 1435671

Piotrowicz, Pawel A., Caneses, Juan F., Showers, Melissa A., Green, Davil L., Goulding, Richard Howell, Caughman, John B. O., Biewer, Theodore M., Rapp, Juergen, and Ruzic, David N.. Direct measurement of the transition from edge to core power coupling in a light-ion helicon source. United States: N. p., Web. doi:10.1063/1.5023924.
Piotrowicz, Pawel A., Caneses, Juan F., Showers, Melissa A., Green, Davil L., Goulding, Richard Howell, Caughman, John B. O., Biewer, Theodore M., Rapp, Juergen, & Ruzic, David N.. Direct measurement of the transition from edge to core power coupling in a light-ion helicon source. United States. doi:10.1063/1.5023924.
Piotrowicz, Pawel A., Caneses, Juan F., Showers, Melissa A., Green, Davil L., Goulding, Richard Howell, Caughman, John B. O., Biewer, Theodore M., Rapp, Juergen, and Ruzic, David N.. 2018. "Direct measurement of the transition from edge to core power coupling in a light-ion helicon source". United States. doi:10.1063/1.5023924.
@article{osti_1456815,
title = {Direct measurement of the transition from edge to core power coupling in a light-ion helicon source},
author = {Piotrowicz, Pawel A. and Caneses, Juan F. and Showers, Melissa A. and Green, Davil L. and Goulding, Richard Howell and Caughman, John B. O. and Biewer, Theodore M. and Rapp, Juergen and Ruzic, David N.},
abstractNote = {Here, we present time-resolved measurements of an edge-to-core power transition in a light-ion (deuterium) helicon discharge in the form of infra-red camera imaging of a thin stainless steel target plate on the Proto-Material Exposure eXperiment device. The time-resolved images measure the two-dimensional distribution of power deposition in the helicon discharge. The discharge displays a mode transition characterized by a significant increase in the on-axis electron density and core power coupling, suppression of edge power coupling, and the formation of a fast-wave radial eigenmode. Although the self-consistent mechanism that drives this transition is not yet understood, the edge-to-core power transition displays characteristics that are consistent with the discharge entering a slow-wave anti-resonant regime. RF magnetic field measurements made across the plasma column, together with the power deposition results, provide direct evidence to support the suppression of the slow-wave in favor of core plasma production by the fast-wave in a light-ion helicon source.},
doi = {10.1063/1.5023924},
journal = {Physics of Plasmas},
number = 5,
volume = 25,
place = {United States},
year = {2018},
month = {5}
}