Since the ITER-like wall in JET (JET-ILW) came into operation, dedicated ITER-like plasma current (Ip) ramp-up (RU) and ramp-down (RD) experiments have been performed and matched to similar discharges with the carbon wall (JET-C). The experiments show that access to H-mode early in the IpRU phase and maintaining H-mode in the IpRD as long as possible are instrumental to achieve low internal plasma inductance (li) and to minimize flux consumption. In JET-ILW, at a given current rise rate similar variations in li(0.7-0.9) are obtained as in JET-C. In most discharges no strong W accumulation is observed. However, in some low density cases during the early phase of the Ipstrong core radiation due to W influx led to hollow electron temperature (Te) profiles. In JET-ILW Zeffis significantly lower than in JET-C. W significantly disturbs the discharge evolution when the W concentration approaches 10-4; this threshold is confirmed by predictive transport modelling using the CRONOS code. IpRD experiments in JET-ILW confirm the result of JET-C that sustained H-mode and elongation reduction are both instrumental in controlling li.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics
Hogeweij, G. M. D., Calabrï¿½, G., Sips, A. C. C., Maggi, C. F., De Tommasi, G. M., Joffrin, E., ... Pï¿½tterich, T. (2015). ITER-like current ramps in JET with ILW: Experiments, modelling and consequences for ITER. Nuclear Fusion, 55(1), -. . https://doi.org/10.1088/0029-5515/55/1/013009