Plasma and Fusion Research

Volume 18, 1402047 (2023)

Regular Articles

Effect of Impurity Ions on Ion Current Flowing into an Ion Sensitive Probe during N2 and H2 Seeding in Hydrogen Plasma
Takuma OKAMOTO, Naomichi EZUMI, Satoshi TOGO, Renato PERILLO1), Naoki SHIGEMATSU, Takumi SETO, Kosuke TAKANASHI, Satoshi TAKAHASHI, Reina MIYAUCHI and Mizuki SAKAMOTO
Plasma Research Center, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
1)
University of California San Diego, San Diego, CA, USA
(Received 24 February 2023 / Accepted 13 April 2023 / Published 14 June 2023)

Abstract

We attempt to interpret the different trends of collected ion currents of the Langmuir probe and the ion sensitive probe (ISP) observed during N2 and H2 seeding in hydrogen plasmas in the divertor simulation experimental module (D-module) in GAMMA10/PDX. The current measured at the ion collector electrode of the ISP shows two distinct bumps. Results can be interpreted with the aid of spectroscopic measurements related to the dominant reaction processes, where nitrogen-induced molecule-activated-recombination (N-MAR) mechanisms produce various ion species, resulting in different measured currents. These experimental findings provide a further understanding of the most relevant plasma-neutral processes occurring in a detached-like plasma scenario in the presence of nitrogen, a candidate for impurity seeding in ITER.

Keywords

divertor, ion species, Larmor radii, ion sensitive probe, MAR, atomic and molecular processes

DOI: 10.1585/pfr.18.1402047

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