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

N. Ezumi, T. Iijima, M. Sakamoto, Y. Nakashima, M. Hirata, M. Ichimura, R. Ikezoe, T. Imai, T. Kariya, I. Katanuma, J. Kohagura, R. Minami, T. Numakura, M. Yoshikawa, S. Togo, M. S. Islam, M. M. Islam, K. Nojiri, A. Terakado, S. JangY. Kinoshita, T. Mikami, S. Yamashita, T. Yoshimoto, T. Hara, A. Hatayama, K. Ichimura, S. Kado, S. Masuzaki, T. Nakano, N. Ohno, S. Sawada, H. Tanaka, A. Tonegawa, R. Perillo

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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.

Original languageEnglish
Article number066030
JournalNuclear Fusion
Volume59
Issue number6
DOIs
Publication statusPublished - May 9 2019

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All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Ezumi, N., Iijima, T., Sakamoto, M., Nakashima, Y., Hirata, M., Ichimura, M., ... Perillo, R. (2019). Synergistic effect of nitrogen and hydrogen seeding gases on plasma detachment in the GAMMA 10/PDX tandem mirror. Nuclear Fusion, 59(6), [066030]. https://doi.org/10.1088/1741-4326/ab1a4a