Plasma and Fusion Research

Volume 17, 1201082 (2022)

Rapid Communications

Observation of Electron Density Rollover in Hydrogen Plasma Produced with DT-ALPHA Device
Keigo YOSHIMURA, Hiroyuki TAKAHASHI, Tomohiro SEINO, Kaoru KUSABIRAKI, Yuki SAKATA, Ryota NISHIMURA, Akinobu MATSUYAMA1) and Kenji TOBITA
Department of Quantum Science and Energy Engineering, Tohoku University, Sendai 980-8579, Japan
1)
National Institutes for Quantum Science and Technology, Rokkasho 039-3212, Japan
(Received 4 April 2022 / Accepted 22 April 2022 / Published 22 June 2022)

Abstract

The rollover of electron density, a common indicator for the onset of volumetric recombination, was observed in hydrogen plasma, for the first time in the DT-ALPHA. Electron density and electron temperature were measured near the plasma production region and secondary gas feeding position with various conditions regarding the amount of hydrogen secondary gas. A rollover of electron density was observed at the secondary gas feeding position, whereas electron density near the plasma production region remained nearly constant. This behavior indicates an enhancement of hydrogen molecular-activated recombination.

Keywords

divertor, molecular-activated recombination, hydrogen plasma, radio-frequency plasma, DT-ALPHA

DOI: 10.1585/pfr.17.1201082

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