Detection of an electron beam in a high density plasma via an electrostatic probe

Majeski, Stephen; Yoo, Jongsoo; Zweben, Stewart; Yamada, Masaaki

doi:10.1088/1361-6587/aabd0e

Title: Detection of an electron beam in a high density plasma via an electrostatic probe

Abstract

Here, an electron beam is detected by a 1D floating potential probe array in a relatively high density (10¹²–10¹³ cm^-3) and low temperature (~5 eV) plasma of the Magnetic Reconnection Experiment. Clear perturbations in the floating potential profile by the electron beam are observed. Based on the floating potential profile and a current balance equation to the probe array tips, the effective width of the electron beam is determined, from which we determine the radial and toroidal beam current density profiles. After the profile of the electron beam is specified from the measured beam current, we demonstrate the consistency of the current balance equation and the location of the perturbation is also in agreement with field line mapping. No significant broadening of the electron beam is observed after the beam propagates for tens of centimeters through the high density plasma. These results prove that the field line mapping is, in principle, possible in high density plasmas.

Authors:

Majeski, Stephen ^[1];

^[2]; Zweben, Stewart ^[2]; Yamada, Masaaki ^[2]

Rensselaer Polytechnic Inst., Troy, NY (United States)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Publication Date:: Tue May 08 00:00:00 EDT 2018

Research Org.:: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:: 1440880

Grant/Contract Number:: AC0209CH11466

Resource Type:: Accepted Manuscript

Journal Name:: Plasma Physics and Controlled Fusion

Additional Journal Information:: Journal Volume: 60; Journal Issue: 7; Journal ID: ISSN 0741-3335

Publisher:: IOP Science

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Electron beam detection; floating potential; fi eld line mapping

Citation Formats


                    Majeski, Stephen, Yoo, Jongsoo, Zweben, Stewart, and Yamada, Masaaki. Detection of an electron beam in a high density plasma via an electrostatic probe.  United States: N. p., 2018. 
Web.  doi:10.1088/1361-6587/aabd0e.

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                    Majeski, Stephen, Yoo, Jongsoo, Zweben, Stewart, & Yamada, Masaaki. Detection of an electron beam in a high density plasma via an electrostatic probe.  United States.  https://doi.org/10.1088/1361-6587/aabd0e

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                    Majeski, Stephen, Yoo, Jongsoo, Zweben, Stewart, and Yamada, Masaaki. Tue .  
"Detection of an electron beam in a high density plasma via an electrostatic probe".  United States.  https://doi.org/10.1088/1361-6587/aabd0e.  https://www.osti.gov/servlets/purl/1440880.

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@article{osti_1440880,

  title        = {Detection of an electron beam in a high density plasma via an electrostatic probe},

  author       = {Majeski, Stephen and Yoo, Jongsoo and Zweben, Stewart and Yamada, Masaaki},

  abstractNote = {Here, an electron beam is detected by a 1D floating potential probe array in a relatively high density (1012–1013 cm-3) and low temperature (~5 eV) plasma of the Magnetic Reconnection Experiment. Clear perturbations in the floating potential profile by the electron beam are observed. Based on the floating potential profile and a current balance equation to the probe array tips, the effective width of the electron beam is determined, from which we determine the radial and toroidal beam current density profiles. After the profile of the electron beam is specified from the measured beam current, we demonstrate the consistency of the current balance equation and the location of the perturbation is also in agreement with field line mapping. No significant broadening of the electron beam is observed after the beam propagates for tens of centimeters through the high density plasma. These results prove that the field line mapping is, in principle, possible in high density plasmas.},

  doi          = {10.1088/1361-6587/aabd0e},

  journal      = {Plasma Physics and Controlled Fusion},

  number       = 7,

  volume       = 60,

  place        = {United States},

  year         = {Tue May 08 00:00:00 EDT 2018},

  month        = {Tue May 08 00:00:00 EDT 2018}

}

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https://doi.org/10.1088/1361-6587/aabd0e

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Figures / Tables:

Figure 1: Schematic for the experimental setup. An electron beam generated by a tungsten filament travels about 20 cm along the magnetic field and reaches a floating potential (V_f) probe array. The filament is radially located at the center of the floating potential probe, 62 cm from the center ofmore »

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