TY  - JOUR
AU  - Brezinsek, Sebastijan
TI  - Plasma-surface interaction in the Be/W environment: Conclusions drawn from the JET-ILW for ITER
JO  - Journal of nuclear materials
VL  - 463
SN  - 0022-3115
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2015-04494
SP  - 11 - 21
PY  - 2015
AB  - The JET ITER-Like Wall experiment (JET-ILW) provides an ideal test bed to investigate plasma-surface interaction (PSI) and plasma operation with the ITER plasma-facing material selection employing beryllium in the main chamber and tungsten in the divertor. The main PSI processes: material erosion and migration, (b) fuel recycling and retention, (c) impurity concentration and radiation have be1en studied and compared between JET-C and JET-ILW. The current physics understanding of these key processes in the JET-ILW revealed that both interpretation of previously obtained carbon results (JET-C) and predictions to ITER need to be revisited. The impact of the first-wall material on the plasma was underestimated.Main observations are: (a) low primary erosion source in H-mode plasmas and reduction of the material migration from the main chamber to the divertor (View the MathML sourcefactor7) as well as within the divertor from plasma-facing to remote areas (View the MathML sourcefactor30-50). The energetic threshold for beryllium sputtering minimises the primary erosion source and inhibits multi-step re-erosion in the divertor. The physical sputtering yield of tungsten is low as 10-510-5 and determined by beryllium ions. (b) Reduction of the long-term fuel retention (View the MathML sourcefactor10-20) in JET-ILW with respect to JET-C. The remaining retention is caused by implantation and co-deposition with beryllium and residual impurities. Outgassing has gained importance and impacts on the recycling properties of beryllium and tungsten. (c) The low effective plasma charge (Zeff=1.2Zeff=1.2) and low radiation capability of beryllium reveal the bare deuterium plasma physics. Moderate nitrogen seeding, reaching Zeff=1.6Zeff=1.6, restores in particular the confinement and the L-H threshold behaviour. ITER-compatible divertor conditions with stable semi-detachment were obtained owing to a higher density limit with ILW. Overall JET demonstrated successful plasma operation in the Be/W material combination and confirms its advantageous PSI behaviour and gives strong support to the ITER material selection.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000358467200003
DO  - DOI:10.1016/j.jnucmat.2014.12.007
UR  - https://juser.fz-juelich.de/record/202205
ER  -