The effects of impurities and core pressure on pedestal stability in Joint European Torus (JET)
2015 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, no 5, 056115Article in journal (Refereed) Published
The H-mode pedestal plays an important role in determining global confinement in tokamaks. In high triangularity H-mode experiments in Joint European Torus with the ITER-like wall (JET-ILW), significantly higher pedestal temperature and global confinement have been achieved with nitrogen seeding. The experimentally observed increase in pedestal height is inconsistent with the stability calculations using the experimental profiles. Numerically, we find that the consistency with stability improvement can be restored if we assume a shift of the pedestal inwards and increased ion dilution due to the impurity seeding. Significantly better confinement and pedestal height have been observed in JET-ILW plasmas when the core pressure is increased. The enhanced pedestal height can be linked to an improvement in edge stability arising from an increase in the Shafranov-shift, higher edge current, and pedestal widening in flux space.
Place, publisher, year, edition, pages
2015. Vol. 22, no 5, 056115
Alpha particles, Magnetoplasma, Stability, Edge stability, Effects of impurities, Global confinement, H-mode pedestal, Joint European Torus, Shafranov shift, Stability calculation, Stability improvement
IdentifiersURN: urn:nbn:se:kth:diva-170269DOI: 10.1063/1.4921413ISI: 000355794300122ScopusID: 2-s2.0-84930006827OAI: oai:DiVA.org:kth-170269DiVA: diva2:833166
QC 201506302015-06-302015-06-292015-07-03Bibliographically approved