Reconfiguration of an Electrothermal-Arc Plasma Source for In Situ PMI Studies

E. G. Lindquist; T. E. Gebhart; D. Elliott; E. W. Garren; Z. He; N. Kafle; C. D. Smith; C. E. Thomas; S. J. Zinkle; T. M. Biewer

doi:10.1080/15361055.2021.1909989

Reconfiguration of an Electrothermal-Arc Plasma Source for In Situ PMI Studies

E. G. Lindquist, T. E. Gebhart, D. Elliott, E. W. Garren, Z. He, N. Kafle, C. D. Smith, C. E. Thomas, S. J. Zinkle, T. M. Biewer

Diagnostics and Control

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

An electrothermal-arc plasma source (ET-Arc) has been developed to produce transient plasma heat and particle fluxes similar to those produced by edge localized modes onto divertor plasma-facing components in tokamaks. The ET-Arc utilizes a capacitive discharge to send current through a 4-mm-diameter, 9-cm-long capillary source liner. The liner material is ablated to form a high-velocity plasma jet that impacts the target downstream. With the current discharge circuit configuration, pulse lengths are 1 to 2 ms in duration and deliver heat fluxes of 0.25 to 2.1 GW m⁻². The plasma was previously characterized with optical emission spectroscopy (OES) on helium emission lines. The He I line ratios were interpreted with collisional radiative analysis to calculate n_e and T_e. The electron temperature and electron density ranged from T_e = 1 to 5 eV and n_e = 10²² to 10²⁸ electrons/m³, respectively. Recently, the vacuum configuration and target of the ET-Arc device were modified to allow greater diagnostic access for plasma-material interaction (PMI) studies and diagnostic development. The diagnostic suite included two Tektronix high-voltage probes to measure the capacitor and discharge potentials, a discharge current monitor, Edgertronic SC1 high-speed cameras to image the discharge, and a FLIR SC4000 infrared camera to estimate heat flux on the target. The system used OES for plasma characterization, but a new Thomson scattering (TS) diagnostic has been implemented. This system is an Advanced Research Projects Agency - Energy (ARPA-E)-funded, portable diagnostic package for spectroscopic measurements of n_e, T_e, n_i, T_i, and v_i, which includes both TS and OES. Additionally, a novel digital holography (DH) surface-imaging diagnostic was implemented to measure erosion rates in situ. Results from ex situ DH characterization of stainless steel targets exposed to the ET-Arc source indicated that surface erosion of ~150 nm per shot occurred and an in situ DH characterization of similar targets was planned. The arc-triggering system will be revised and optimized to better synchronize with the laser diagnostics. Details of the reconfigured ET-Arc source are reported here.

Original language	English
Pages (from-to)	921-927
Number of pages	7
Journal	Fusion Science and Technology
Volume	77
Issue number	7-8
DOIs	https://doi.org/10.1080/15361055.2021.1909989
State	Published - 2021

Funding

This work was supported by ORNL managed by UT-Battelle, LLC for the U.S. Department of Energy (DOE) under contract number DEAC05-00OR22725. This manuscript has been coauthored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the DOE. The U.S. government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the peer-reviewed, accepted form of this manuscript, or allow others to do so, for U.S. government purposes. DOE 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). This work was supported by ORNL managed by UT-Battelle, LLC for the U.S. Department of Energy (DOE) under contract number DEAC05-00OR22725. This manuscript has been coauthored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the DOE. The U.S. government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the peer-reviewed, accepted form of this manuscript, or allow others to do so, for U.S. government purposes. DOE 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
DOE Public Access Plan
U.S. Government
U.S. Department of Energy	DEAC05-00OR22725
Oak Ridge National Laboratory
UT-Battelle	DE-AC05-00OR22725

Keywords

Electrothermal-arc plasma source
diagnostics
high heat flux
plasma-material interactions

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1080/15361055.2021.1909989

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title = "Reconfiguration of an Electrothermal-Arc Plasma Source for In Situ PMI Studies",

abstract = "An electrothermal-arc plasma source (ET-Arc) has been developed to produce transient plasma heat and particle fluxes similar to those produced by edge localized modes onto divertor plasma-facing components in tokamaks. The ET-Arc utilizes a capacitive discharge to send current through a 4-mm-diameter, 9-cm-long capillary source liner. The liner material is ablated to form a high-velocity plasma jet that impacts the target downstream. With the current discharge circuit configuration, pulse lengths are 1 to 2 ms in duration and deliver heat fluxes of 0.25 to 2.1 GW m−2. The plasma was previously characterized with optical emission spectroscopy (OES) on helium emission lines. The He I line ratios were interpreted with collisional radiative analysis to calculate ne and Te. The electron temperature and electron density ranged from Te = 1 to 5 eV and ne = 1022 to 1028 electrons/m3, respectively. Recently, the vacuum configuration and target of the ET-Arc device were modified to allow greater diagnostic access for plasma-material interaction (PMI) studies and diagnostic development. The diagnostic suite included two Tektronix high-voltage probes to measure the capacitor and discharge potentials, a discharge current monitor, Edgertronic SC1 high-speed cameras to image the discharge, and a FLIR SC4000 infrared camera to estimate heat flux on the target. The system used OES for plasma characterization, but a new Thomson scattering (TS) diagnostic has been implemented. This system is an Advanced Research Projects Agency - Energy (ARPA-E)-funded, portable diagnostic package for spectroscopic measurements of ne, Te, ni, Ti, and vi, which includes both TS and OES. Additionally, a novel digital holography (DH) surface-imaging diagnostic was implemented to measure erosion rates in situ. Results from ex situ DH characterization of stainless steel targets exposed to the ET-Arc source indicated that surface erosion of ~150 nm per shot occurred and an in situ DH characterization of similar targets was planned. The arc-triggering system will be revised and optimized to better synchronize with the laser diagnostics. Details of the reconfigured ET-Arc source are reported here.",

keywords = "Electrothermal-arc plasma source, diagnostics, high heat flux, plasma-material interactions",

author = "Lindquist, {E. G.} and Gebhart, {T. E.} and D. Elliott and Garren, {E. W.} and Z. He and N. Kafle and Smith, {C. D.} and Thomas, {C. E.} and Zinkle, {S. J.} and Biewer, {T. M.}",

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AU - Lindquist, E. G.

AU - Gebhart, T. E.

AU - Elliott, D.

AU - Garren, E. W.

AU - He, Z.

AU - Kafle, N.

AU - Smith, C. D.

AU - Thomas, C. E.

AU - Zinkle, S. J.

AU - Biewer, T. M.

PY - 2021

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N2 - An electrothermal-arc plasma source (ET-Arc) has been developed to produce transient plasma heat and particle fluxes similar to those produced by edge localized modes onto divertor plasma-facing components in tokamaks. The ET-Arc utilizes a capacitive discharge to send current through a 4-mm-diameter, 9-cm-long capillary source liner. The liner material is ablated to form a high-velocity plasma jet that impacts the target downstream. With the current discharge circuit configuration, pulse lengths are 1 to 2 ms in duration and deliver heat fluxes of 0.25 to 2.1 GW m−2. The plasma was previously characterized with optical emission spectroscopy (OES) on helium emission lines. The He I line ratios were interpreted with collisional radiative analysis to calculate ne and Te. The electron temperature and electron density ranged from Te = 1 to 5 eV and ne = 1022 to 1028 electrons/m3, respectively. Recently, the vacuum configuration and target of the ET-Arc device were modified to allow greater diagnostic access for plasma-material interaction (PMI) studies and diagnostic development. The diagnostic suite included two Tektronix high-voltage probes to measure the capacitor and discharge potentials, a discharge current monitor, Edgertronic SC1 high-speed cameras to image the discharge, and a FLIR SC4000 infrared camera to estimate heat flux on the target. The system used OES for plasma characterization, but a new Thomson scattering (TS) diagnostic has been implemented. This system is an Advanced Research Projects Agency - Energy (ARPA-E)-funded, portable diagnostic package for spectroscopic measurements of ne, Te, ni, Ti, and vi, which includes both TS and OES. Additionally, a novel digital holography (DH) surface-imaging diagnostic was implemented to measure erosion rates in situ. Results from ex situ DH characterization of stainless steel targets exposed to the ET-Arc source indicated that surface erosion of ~150 nm per shot occurred and an in situ DH characterization of similar targets was planned. The arc-triggering system will be revised and optimized to better synchronize with the laser diagnostics. Details of the reconfigured ET-Arc source are reported here.

AB - An electrothermal-arc plasma source (ET-Arc) has been developed to produce transient plasma heat and particle fluxes similar to those produced by edge localized modes onto divertor plasma-facing components in tokamaks. The ET-Arc utilizes a capacitive discharge to send current through a 4-mm-diameter, 9-cm-long capillary source liner. The liner material is ablated to form a high-velocity plasma jet that impacts the target downstream. With the current discharge circuit configuration, pulse lengths are 1 to 2 ms in duration and deliver heat fluxes of 0.25 to 2.1 GW m−2. The plasma was previously characterized with optical emission spectroscopy (OES) on helium emission lines. The He I line ratios were interpreted with collisional radiative analysis to calculate ne and Te. The electron temperature and electron density ranged from Te = 1 to 5 eV and ne = 1022 to 1028 electrons/m3, respectively. Recently, the vacuum configuration and target of the ET-Arc device were modified to allow greater diagnostic access for plasma-material interaction (PMI) studies and diagnostic development. The diagnostic suite included two Tektronix high-voltage probes to measure the capacitor and discharge potentials, a discharge current monitor, Edgertronic SC1 high-speed cameras to image the discharge, and a FLIR SC4000 infrared camera to estimate heat flux on the target. The system used OES for plasma characterization, but a new Thomson scattering (TS) diagnostic has been implemented. This system is an Advanced Research Projects Agency - Energy (ARPA-E)-funded, portable diagnostic package for spectroscopic measurements of ne, Te, ni, Ti, and vi, which includes both TS and OES. Additionally, a novel digital holography (DH) surface-imaging diagnostic was implemented to measure erosion rates in situ. Results from ex situ DH characterization of stainless steel targets exposed to the ET-Arc source indicated that surface erosion of ~150 nm per shot occurred and an in situ DH characterization of similar targets was planned. The arc-triggering system will be revised and optimized to better synchronize with the laser diagnostics. Details of the reconfigured ET-Arc source are reported here.

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Reconfiguration of an Electrothermal-Arc Plasma Source for In Situ PMI Studies

Abstract

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Keywords

UN SDGs

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