Evidence of electron heating at different radial locations on Proto-MPEX

C. Lau; J. F. Caneses; T. S. Bigelow; T. M. Biewer; J. B.O. Caughman; R. H. Goulding; P. A. Piotrowicz; J. Rapp; H. B. Ray; M. Showers

doi:10.1063/1.5083814

Evidence of electron heating at different radial locations on Proto-MPEX

C. Lau, J. F. Caneses, T. S. Bigelow, T. M. Biewer, J. B.O. Caughman, R. H. Goulding, P. A. Piotrowicz, J. Rapp, H. B. Ray, M. Showers

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12 Scopus citations

Abstract

This paper reports on the observation of controlled underdense electron heating for high heat flux applications in the Prototype Material Plasma Exposure eXperiment. The goal of this experiment is to demonstrate the source and heating concepts to create a high intensity plasma at material targets to study plasma-material interactions in similar plasma conditions to magnetic fusion divertors. A 80 kW helicon source at 13.56 MHz is used for the plasma density production and a 15 kW microwave source at 28 GHz is used for electron heating. For electron densities ∼5 × 10¹⁸ m^-3, the electron temperature at the target location increases from 2 eV to 5 eV and the core heat flux increases by a factor of 5. It is shown that the radial profile of the heat flux delivered at the target can be controlled by either the background plasma density or the magnetic field. Analysis suggests that the electron heating is due to heating near the upper-hybrid resonance layer and that this heating scenario may scale up to divertor-relevant electron densities ∼5 × 10¹⁹ m^-3 by increasing the microwave driving frequency to 105 GHz.

Original language	English
Article number	032503
Journal	Physics of Plasmas
Volume	26
Issue number	3
DOIs	https://doi.org/10.1063/1.5083814
State	Published - Mar 1 2019

Funding

The author(s) would like to thank the Proto-MPEX team for making this work possible. This work was supported by U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Contract No. DE-AC05-00OR22725. This manuscript was authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Funders	Funder number
U.S. Department of Energy
Office of Science
Fusion Energy Sciences	DE-AC05-00OR22725

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title = "Evidence of electron heating at different radial locations on Proto-MPEX",

abstract = "This paper reports on the observation of controlled underdense electron heating for high heat flux applications in the Prototype Material Plasma Exposure eXperiment. The goal of this experiment is to demonstrate the source and heating concepts to create a high intensity plasma at material targets to study plasma-material interactions in similar plasma conditions to magnetic fusion divertors. A 80 kW helicon source at 13.56 MHz is used for the plasma density production and a 15 kW microwave source at 28 GHz is used for electron heating. For electron densities ∼5 × 1018 m-3, the electron temperature at the target location increases from 2 eV to 5 eV and the core heat flux increases by a factor of 5. It is shown that the radial profile of the heat flux delivered at the target can be controlled by either the background plasma density or the magnetic field. Analysis suggests that the electron heating is due to heating near the upper-hybrid resonance layer and that this heating scenario may scale up to divertor-relevant electron densities ∼5 × 1019 m-3 by increasing the microwave driving frequency to 105 GHz.",

author = "C. Lau and Caneses, {J. F.} and Bigelow, {T. S.} and Biewer, {T. M.} and Caughman, {J. B.O.} and Goulding, {R. H.} and Piotrowicz, {P. A.} and J. Rapp and Ray, {H. B.} and M. Showers",

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AU - Biewer, T. M.

AU - Caughman, J. B.O.

AU - Goulding, R. H.

AU - Piotrowicz, P. A.

AU - Rapp, J.

AU - Ray, H. B.

AU - Showers, M.

PY - 2019/3/1

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N2 - This paper reports on the observation of controlled underdense electron heating for high heat flux applications in the Prototype Material Plasma Exposure eXperiment. The goal of this experiment is to demonstrate the source and heating concepts to create a high intensity plasma at material targets to study plasma-material interactions in similar plasma conditions to magnetic fusion divertors. A 80 kW helicon source at 13.56 MHz is used for the plasma density production and a 15 kW microwave source at 28 GHz is used for electron heating. For electron densities ∼5 × 1018 m-3, the electron temperature at the target location increases from 2 eV to 5 eV and the core heat flux increases by a factor of 5. It is shown that the radial profile of the heat flux delivered at the target can be controlled by either the background plasma density or the magnetic field. Analysis suggests that the electron heating is due to heating near the upper-hybrid resonance layer and that this heating scenario may scale up to divertor-relevant electron densities ∼5 × 1019 m-3 by increasing the microwave driving frequency to 105 GHz.

AB - This paper reports on the observation of controlled underdense electron heating for high heat flux applications in the Prototype Material Plasma Exposure eXperiment. The goal of this experiment is to demonstrate the source and heating concepts to create a high intensity plasma at material targets to study plasma-material interactions in similar plasma conditions to magnetic fusion divertors. A 80 kW helicon source at 13.56 MHz is used for the plasma density production and a 15 kW microwave source at 28 GHz is used for electron heating. For electron densities ∼5 × 1018 m-3, the electron temperature at the target location increases from 2 eV to 5 eV and the core heat flux increases by a factor of 5. It is shown that the radial profile of the heat flux delivered at the target can be controlled by either the background plasma density or the magnetic field. Analysis suggests that the electron heating is due to heating near the upper-hybrid resonance layer and that this heating scenario may scale up to divertor-relevant electron densities ∼5 × 1019 m-3 by increasing the microwave driving frequency to 105 GHz.

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Evidence of electron heating at different radial locations on Proto-MPEX

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