Understanding tungsten erosion during inter/intra-ELM periods in He-dominated JET-ILW plasmas

A. Huber, S. Brezinsek, V. Huber, E. R. Solano, G. Sergienko, I. Borodkina, S. Aleiferis, A. Meigs, D. Tskhakaya, M. Sertoli, M. Baruzzo, D. Borodin, P. Carvalho, E. Delabie, D. Douai, A. Kirschner, K. Lawson, Ch Linsmeier, J. Mailloux, S. MenmuirPh Mertens, E. Pawelec, J. Romazanov, A. Shaw

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Abstract

Tungsten erosion was quantified during inter/intra-ELM periods in He-dominated JET-ILW plasmas by optical emission spectroscopy. The intra-ELM tungsten sputtering in helium plasmas, which dominates the total W source, prevails by a factor of about 4 over inter-ELM sputtering in the investigated ELM frequency range from 90 Hz-120 Hz. He ions are mainly responsible for the W erosion during the ELMs in He plasmas. The strong in/out asymmetry of the ELM-induced W erosion is observed in He plasmas even at high ELM frequencies beyond 100 Hz. In Ohmic/L-mode plasmas and during the H-mode inter-ELM plasma phases both He2+ and Be2+ ionic species are major contributors to the W erosion. Their contribution depends on the electron temperature in the divertor: For Te > 15 eV both species cause significant W sputtering, for Te < 15 eV, Be2+ ions are solely responsible for the W erosion. Tungsten erosion during in both inter and intra-ELM periods in He-dominated plasmas are significantly larger than in deuterium plasmas. It is 15-25 times larger during the inter-ELM phase and in L-mode discharges at Te = 25-30 eV. On the other hand, the ELM-induced W source is by a factor of 3 larger than in D plasmas.

Original languageEnglish
Article number124046
JournalPhysica Scripta
Volume96
Issue number12
DOIs
StatePublished - Dec 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021 EURATOM.

Keywords

  • JET-ILW
  • helium plasma
  • optical emission spectroscopy
  • plasma-material interactions
  • tungsten divertor
  • tungsten erosion

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