skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Experimental observation of ion beams in the Madison Helicon eXperiment

Abstract

Argon ion beams up to E{sub b} = 165 eV at P{sub rf} = 500 W are observed in the Madison Helicon eXperiment (MadHeX) helicon source with a magnetic nozzle. A two-grid retarding potential analyzer (RPA) is used to measure the ion energy distribution, and emissive and rf-filtered Langmuir probes measure the plasma potential, electron density, and temperature. The supersonic ion beam (M = v{sub i}/c{sub s} up to 5) forms over tens of Debye lengths and extends spatially for a few ion-neutral charge-exchange mean free paths. The parametric variation of the ion beam energy is explored, including flow rate, rf power, and magnetic field dependence. The beam energy is equal to the difference in plasma potentials in the Pyrex chamber and the grounded expansion chamber. The plasma potential in the expansion chamber remains near the predicted eV{sub p} {approx} 5kT{sub e} for argon, but the upstream potential is much higher, likely due to wall charging, resulting in accelerated ion beam energies E{sub b} = e[V{sub beam} - V{sub plasma}] > 10kT{sub e}.

Authors:
; ;  [1]
  1. Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
Publication Date:
OSTI Identifier:
21546973
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 18; Journal Issue: 6; Other Information: DOI: 10.1063/1.3596537; (c) 2011 American Institute of Physics; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON IONS; CHARGE EXCHANGE; ELECTRON DENSITY; ELECTRON TEMPERATURE; ENERGY SPECTRA; EXPANSION CHAMBERS; FLOW RATE; ION BEAMS; LANGMUIR PROBE; MAGNETIC FIELDS; MEAN FREE PATH; PLASMA POTENTIAL; BEAMS; CHARGED PARTICLES; CLOUD CHAMBERS; ELECTRIC POTENTIAL; ELECTRIC PROBES; GAS TRACK DETECTORS; IONS; MEASURING INSTRUMENTS; PROBES; RADIATION DETECTORS; SPECTRA

Citation Formats

Wiebold, Matt, Sung, Yung-Ta, and Scharer, John E. Experimental observation of ion beams in the Madison Helicon eXperiment. United States: N. p., 2011. Web. doi:10.1063/1.3596537.
Wiebold, Matt, Sung, Yung-Ta, & Scharer, John E. Experimental observation of ion beams in the Madison Helicon eXperiment. United States. https://doi.org/10.1063/1.3596537
Wiebold, Matt, Sung, Yung-Ta, and Scharer, John E. 2011. "Experimental observation of ion beams in the Madison Helicon eXperiment". United States. https://doi.org/10.1063/1.3596537.
@article{osti_21546973,
title = {Experimental observation of ion beams in the Madison Helicon eXperiment},
author = {Wiebold, Matt and Sung, Yung-Ta and Scharer, John E},
abstractNote = {Argon ion beams up to E{sub b} = 165 eV at P{sub rf} = 500 W are observed in the Madison Helicon eXperiment (MadHeX) helicon source with a magnetic nozzle. A two-grid retarding potential analyzer (RPA) is used to measure the ion energy distribution, and emissive and rf-filtered Langmuir probes measure the plasma potential, electron density, and temperature. The supersonic ion beam (M = v{sub i}/c{sub s} up to 5) forms over tens of Debye lengths and extends spatially for a few ion-neutral charge-exchange mean free paths. The parametric variation of the ion beam energy is explored, including flow rate, rf power, and magnetic field dependence. The beam energy is equal to the difference in plasma potentials in the Pyrex chamber and the grounded expansion chamber. The plasma potential in the expansion chamber remains near the predicted eV{sub p} {approx} 5kT{sub e} for argon, but the upstream potential is much higher, likely due to wall charging, resulting in accelerated ion beam energies E{sub b} = e[V{sub beam} - V{sub plasma}] > 10kT{sub e}.},
doi = {10.1063/1.3596537},
url = {https://www.osti.gov/biblio/21546973}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 6,
volume = 18,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2011},
month = {Wed Jun 15 00:00:00 EDT 2011}
}