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Title: Broad ion energy distributions in helicon wave-coupled helium plasma

Authors:
ORCiD logo [1];  [1];  [1]
  1. Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, Massachusetts 02139, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1361886
Grant/Contract Number:
FC02-99ER54512; SC00-02060
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 5; Related Information: CHORUS Timestamp: 2018-02-14 23:51:55; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Woller, K. B., Whyte, D. G., and Wright, G. M. Broad ion energy distributions in helicon wave-coupled helium plasma. United States: N. p., 2017. Web. doi:10.1063/1.4983315.
Woller, K. B., Whyte, D. G., & Wright, G. M. Broad ion energy distributions in helicon wave-coupled helium plasma. United States. doi:10.1063/1.4983315.
Woller, K. B., Whyte, D. G., and Wright, G. M. Mon . "Broad ion energy distributions in helicon wave-coupled helium plasma". United States. doi:10.1063/1.4983315.
@article{osti_1361886,
title = {Broad ion energy distributions in helicon wave-coupled helium plasma},
author = {Woller, K. B. and Whyte, D. G. and Wright, G. M.},
abstractNote = {},
doi = {10.1063/1.4983315},
journal = {Physics of Plasmas},
number = 5,
volume = 24,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4983315

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  • The characteristics of high-density helicon wave plasma generated in a quartz tube of 10 cm in diameter have been studied. The optimum conditions for efficiently exciting helicon wave plasma have been investigated. It is also observed that plasma fully ionized by helicon waves has ion pumping effect. Whether the discharge is inductive or capacitive, the plasma potential is important, since it determines the energy of the ion incident on the wall. It is investigated theoretically and experimentally that the fluctuation of the plasma potentials influences the ion energy distribution functions monitored by the retarding field energy analyzer. It is alsomore » observed that the plasma potential fluctuates with peak-to-peak voltage {ital V}{sub p{endash}p} in the low-density mode. The radio-frequency modulation to the plasma potential is weaker in the helicon mode than in the low mode. {copyright} {ital 1996 American Institute of Physics.}« less
  • The currently employed converter-type negative ion source at Los Alamos Neutron Science Center (LANSCE) is based on cesium enhanced surface production of H{sup -} ion beams in a filament-driven discharge. The extracted H{sup -} beam current is limited by the achievable plasma density, which depends primarily on the electron emission current from the filaments. The emission current can be increased by increasing the filament temperature but, unfortunately, this leads not only to shorter filament lifetime but also to an increase in metal evaporation from the filament, which degrades the performance of the H{sup -} conversion surface. In order to overcomemore » these limitations we have designed and tested a prototype of a surface conversion H{sup -} ion source, based on excitation of helicon plasma wave mode with an external antenna. The source has been operated with and without cesium injection. An H{sup -} beam current of over 12 mA has been transported through the low energy beam transport of the LANSCE ion source test stand. The results of these experiments and the effects of different source parameters on the extracted beam current are presented. The limitations of the source prototype are discussed and future improvements are proposed based on the experimental observations.« less
  • The behavior of instabilities, excited by the anisotropy of the distribution of ion velocities, in the case of a plasma penetrated by a helicon wave, is studied. The modification of dielectric properties of the plasma, induced by the helicon wave, influences substantially the onset of instabiiities and reduces their growth rates. Thus a dynamic stabilization for some dangerous microinstabilities, which are based on collective interaction between both plasma species, could be achieved. (auth)
  • The currently employed converter-type negative ion source at Los Alamos Neutron Science Center (LANSCE) is based on cesium enhanced surface production of H{sup -} ion beams in a filament-driven discharge. The extracted H{sup -} beam current is limited by the achievable plasma density, which depends primarily on the electron emission current from the filaments. The emission current can be increased by increasing the filament temperature but, unfortunately, this leads not only to shorter filament lifetime but also to an increase in metal evaporation from the filament, which degrades the performance of the H{sup -} conversion surface. In order to overcomemore » these limitations we have designed and tested a prototype of a surface conversion H{sup -} ion source, based on excitation of helicon plasma wave mode with an external antenna. The source has been operated with and without cesium injection. An H{sup -} beam current of over 12 mA has been transported through the low energy beam transport of the LANSCE ion source test stand. The results of these experiments and the effects of different source parameters on the extracted beam current are presented. The limitations of the source prototype are discussed and future improvements are proposed based on the experimental observations.« less
  • With the energy resolved quadrupole mass spectrometer and hybrid simulation, the influence of low-frequency (LF) source parameters on the ion energy distributions (IEDs) of argon ions impinging on the grounded electrode was studied, both experimentally and numerically, in a dual frequency capacitively coupled plasma. It was shown that for decreasing LF or increasing LF power, the high energy peak in IEDs shifts toward the high energy region significantly. The simulation results were in general agreement with the experimental data.