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 language | English |
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Article number | 124046 |
Journal | Physica Scripta |
Volume | 96 |
Issue number | 12 |
DOIs | |
State | Published - Dec 2021 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2021 EURATOM.
Keywords
- JET-ILW
- helium plasma
- optical emission spectroscopy
- plasma-material interactions
- tungsten divertor
- tungsten erosion