Langmuir probe measurements of scrape-off layer conditions in RF-driven plasmas in TST-2

James H.P. Rice; Naoto Tsujii; Yuichi Takase; Akira Ejiri; Osamu Watanabe; Hibiki Yamazaki; Yi Peng; Kotaro Iwasaki; Yuki Aoi; Yongtae Ko; Kyohei Matsuzaki; Yuki Osawa

doi:10.1585/PFR.15.2402009

Langmuir probe measurements of scrape-off layer conditions in RF-driven plasmas in TST-2

James H.P. Rice^*, Naoto Tsujii, Yuichi Takase, Akira Ejiri, Osamu Watanabe, Hibiki Yamazaki, Yi Peng, Kotaro Iwasaki, Yuki Aoi, Yongtae Ko, Kyohei Matsuzaki, Yuki Osawa

^*Corresponding author for this work

Biochemistry and Molecular Genetics

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

4 Scopus citations

Abstract

A new Langmuir probe has been designed and installed in TST-2 for measurements of Scrape-Off Layer plasmas (SOL). Non-inductive current drive is considered essential for spherical tokamak reactors. It has previously been shown that a large amount of injected Lower HybridWave (LHW) power is lost in the SOL [1]. A full density profile of SOL conditions is necessary to accurately simulate the propagation of LHW in TST-2. A new probe was designed for durability, larger signal and Mach probe measurements. The new probe has been installed in TST-2 and results have been obtained. Temperature measurements show T_e = 30-50 eV during RF injection and < 10 eV otherwise. Density measurements show n_e = 2.0 x 10¹⁵ m^-3 and 1.5 x 1016 m^-3 during flat-top RF power injection from Outboard-and Top-launch antennas, respectively. This is above the cut-off density for the 200MHz LHW (5 x 10¹⁴ m^-3) in TST-2, thus LHW can propagate through SOL plasma.

Original language	English (US)
Article number	2402009
Journal	Plasma and Fusion Research
Volume	15
DOIs	https://doi.org/10.1585/PFR.15.2402009
State	Published - 2020

Funding

This work was supported by Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (S) (21226021), by National Institute for Fusion Science Collaboration Research Programs NIFS14KOCR001, NIFS18KOAR022 and NIFS12KUTR078. This work was also supported in part by Japan/US Cooperation in Fusion Research and Development and US DoE Cooperative Agreement DE-FC02-04ER54698.

Keywords

Langmuir probe
Lower-hybrid wave
Mach probe
Spherical tokamak

ASJC Scopus subject areas

Condensed Matter Physics

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10.1585/PFR.15.2402009

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title = "Langmuir probe measurements of scrape-off layer conditions in RF-driven plasmas in TST-2",

abstract = "A new Langmuir probe has been designed and installed in TST-2 for measurements of Scrape-Off Layer plasmas (SOL). Non-inductive current drive is considered essential for spherical tokamak reactors. It has previously been shown that a large amount of injected Lower HybridWave (LHW) power is lost in the SOL [1]. A full density profile of SOL conditions is necessary to accurately simulate the propagation of LHW in TST-2. A new probe was designed for durability, larger signal and Mach probe measurements. The new probe has been installed in TST-2 and results have been obtained. Temperature measurements show Te = 30-50 eV during RF injection and < 10 eV otherwise. Density measurements show ne = 2.0 x 1015 m-3 and 1.5 x 1016 m-3 during flat-top RF power injection from Outboard-and Top-launch antennas, respectively. This is above the cut-off density for the 200MHz LHW (5 x 1014 m-3) in TST-2, thus LHW can propagate through SOL plasma.",

keywords = "Langmuir probe, Lower-hybrid wave, Mach probe, Spherical tokamak",

author = "Rice, {James H.P.} and Naoto Tsujii and Yuichi Takase and Akira Ejiri and Osamu Watanabe and Hibiki Yamazaki and Yi Peng and Kotaro Iwasaki and Yuki Aoi and Yongtae Ko and Kyohei Matsuzaki and Yuki Osawa",

note = "Publisher Copyright: {\textcopyright} 2020 The Japan Society of Plasma Science and Nuclear Fusion Research.",

year = "2020",

doi = "10.1585/PFR.15.2402009",

language = "English (US)",

volume = "15",

journal = "Plasma and Fusion Research",

issn = "1880-6821",

publisher = "The Japan Society of Plasma Science and Nuclear Fusion Research (JSPF)",

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TY - JOUR

T1 - Langmuir probe measurements of scrape-off layer conditions in RF-driven plasmas in TST-2

AU - Rice, James H.P.

AU - Tsujii, Naoto

AU - Takase, Yuichi

AU - Ejiri, Akira

AU - Watanabe, Osamu

AU - Yamazaki, Hibiki

AU - Peng, Yi

AU - Iwasaki, Kotaro

AU - Aoi, Yuki

AU - Ko, Yongtae

AU - Matsuzaki, Kyohei

AU - Osawa, Yuki

PY - 2020

Y1 - 2020

N2 - A new Langmuir probe has been designed and installed in TST-2 for measurements of Scrape-Off Layer plasmas (SOL). Non-inductive current drive is considered essential for spherical tokamak reactors. It has previously been shown that a large amount of injected Lower HybridWave (LHW) power is lost in the SOL [1]. A full density profile of SOL conditions is necessary to accurately simulate the propagation of LHW in TST-2. A new probe was designed for durability, larger signal and Mach probe measurements. The new probe has been installed in TST-2 and results have been obtained. Temperature measurements show Te = 30-50 eV during RF injection and < 10 eV otherwise. Density measurements show ne = 2.0 x 1015 m-3 and 1.5 x 1016 m-3 during flat-top RF power injection from Outboard-and Top-launch antennas, respectively. This is above the cut-off density for the 200MHz LHW (5 x 1014 m-3) in TST-2, thus LHW can propagate through SOL plasma.

AB - A new Langmuir probe has been designed and installed in TST-2 for measurements of Scrape-Off Layer plasmas (SOL). Non-inductive current drive is considered essential for spherical tokamak reactors. It has previously been shown that a large amount of injected Lower HybridWave (LHW) power is lost in the SOL [1]. A full density profile of SOL conditions is necessary to accurately simulate the propagation of LHW in TST-2. A new probe was designed for durability, larger signal and Mach probe measurements. The new probe has been installed in TST-2 and results have been obtained. Temperature measurements show Te = 30-50 eV during RF injection and < 10 eV otherwise. Density measurements show ne = 2.0 x 1015 m-3 and 1.5 x 1016 m-3 during flat-top RF power injection from Outboard-and Top-launch antennas, respectively. This is above the cut-off density for the 200MHz LHW (5 x 1014 m-3) in TST-2, thus LHW can propagate through SOL plasma.

KW - Langmuir probe

KW - Lower-hybrid wave

KW - Mach probe

KW - Spherical tokamak

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Langmuir probe measurements of scrape-off layer conditions in RF-driven plasmas in TST-2

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Keywords

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