PEP-39 Update from JET-ILW: Configuration effects on L-H power threshold and H-mode

Abstract

In JET-ILW Corner (CC) plasmas the L-H transition power threshold (PLH) is higher than in the Horizontal Target (HT) ones, indicating poorer L-mode confinement in Corner. The ne,min dependence on both plasma configuration and plasma current was shown. In D plasmas, typically ne,min(CC)~0.3 of the Greenwald density (nGW), while ne,min(HT)~0.4 nGW, for various Btor and Ip L-H transition datasets. A reduction in ne,min when Ip is lower was shown. Despite the fact that HT has lower PLH, for the same gas fuelling and input power, the H-mode in HT has poorer confinement than CC. In the CC time-window density is lower and temperatures higher, and steady large ELMs are observed. In the HT time window, pedestal density is higher and temperatures lower, a mixture of small and large ELMs is present. A higher ratio of heating power to PLH threshold does not correlate with good confinement or steady type I ELMy regime. Additional L-H transition experiments investigating the configuration effect and the relationship between Ip and ne,min (at fixed Btor) were requested, even if in Carbon devices.Work supported in part by Spanish National Plan for Scientific and Technical Research and Innovation grant number PID2021-127727OB-I00, funded by MCIN/AEI/ 10.13039/501100011033 and ERDF ‘A way of making Europe