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Synergistic effect of nitrogen and hydrogen seeding gases on plasma detachment in the GAMMA 10/PDX tandem mirror

Author
Abstract

We have investigated the synergistic effect of a combination of various impurity gases and hydrogen gas on plasma detachment of high temperature plasma, equivalent to scrape-off layer plasma of tokamaks in the GAMMA 10/PDX end region, utilizing an open magnetic field configuration. A small puff of an impurity gas (N2, Ne, Ar, Kr, Xe) in combination with a puff of H2 gas is examined to evaluate their synergistic effect on the formation of detached plasma; the following results are obtained. (i) A combination of N2 and H2 puffs showed a clear decrease of electron density and ion flux; (ii) N2 and H2 puffs form a strong density gradient along the axial direction; and (iii) other noble impurity gases showed an insufficient synergistic effect. The new results indicate the possibility of achieving a reliable divertor operation scheme and the importance of a deeper understanding of the H2 and N2 assisted recombination process.

Year of Publication
2019
Journal
Nuclear Fusion
Volume
59
Issue
6
Number of Pages
066030
DOI
10.1088/1741-4326/ab1a4a
PId
007c3e22957d928dbccf925e4cdccbd5
Alternate Journal
Nucl. Fusion
Journal Article
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