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Article Dans Une Revue Nuclear Fusion Année : 2019

Erosion, screening, and migration of tungsten in the JET divertor

Résumé

The erosion of tungsten (W), induced by the bombardment of plasma andimpurity particles, determines the lifetime of plasma-facing componentsas well as impacting on plasma performance by the influx of W into theconfined region. The screening of W by the divertor and the transport ofW in the plasma determines largely the W content in the plasma core, butthe W source strength itself has a vital impact on this process. The JETtokamak experiment provides access to a large set of W erosion-determining parameters and permits a detailed description of the Wsource in the divertor closest to the ITER one: (i) effective sputteringyields and fluxes as function of impact energy of intrinsic (Be, C) andextrinsic (Ne, N) impurities as well as hydrogenic isotopes (H, D) aredetermined and predictions for the tritium (T) isotope are made. Thisincludes the quantification of intra- and inter-edge localised mode(ELM) contributions to the total W source in H-mode plasmas which varyowing to the complex flux compositions and energy distributions in thecorresponding phases. The sputtering threshold behaviour and thespectroscopic composition analysis provides an insight in the dominatingspecies and plasma phases causing W erosion. (ii) The interplay betweenthe net and gross W erosion source is discussed considering (prompt) re-deposition, thus, the immediate return of W ions back to the surface dueto their large Larmor radius, and surface roughness, thus, thedifference between smooth bulk-W and rough W-coating components used inthe JET divertor. Both effects impact on the balance equation of local Werosion and deposition. (iii) Post-mortem analysis reveals the neterosion/deposition pattern and the W migration paths over long periodsof plasma operation identifying the net W transport to remote areas.This W transport is related to the divertor plasma regime, e.g. attachedoperation with high impact energies of impinging particles or detachedoperation, as well as to the applied magnetic configuration in thedivertor, e.g. close divertor with good geometrical screening of W oropen divertor configuration with poor screening.

Dates et versions

hal-03742701 , version 1 (02-08-2022)

Identifiants

Citer

S. Brezinsek, A. Kirschner, M. Mayer, A. Baron-Wiechec, I. Borodkina, et al.. Erosion, screening, and migration of tungsten in the JET divertor. Nuclear Fusion, 2019, 59, pp.096035. ⟨10.1088/1741-4326/ab2aef⟩. ⟨hal-03742701⟩
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