The impact of fuelling and W radiation on the performance of high-power, ITER-baseline scenario plasmas in JET-ILW

The impact of fuelling and W radiation on the performance of high-power, ITER-baseline scenario plasmas in JET-ILW

The impact of fuelling and W radiation on the performance of high-power, ITER-baseline scenario plasmas in JET-ILW 150 150 Mathew
UKAEA-CCFE-PR(21)35

The impact of fuelling and W radiation on the performance of high-power, ITER-baseline scenario plasmas in JET-ILW

Sustained operation of high-performance, ITER-baseline scenario plasmas at the high levels of input power (~< 40MA) required to achieve ~ 15 MW of D-T fusion power in JET-ILW requires careful optimisation of the fuelling to avoid an unacceptable disruption rate due to excessive radiation, primarily from W impurities, which are sputtered by edge-localised modes (ELMs) from the divertor targets. By using a train of ELM-pacing pellets from a high-frequency pellet injector to promote regular ELMs, which  flush W and other impurities from the confined plasma, such high-performance plasmas can be sustained (for ~ 5 s) while maintaining a high normalised confinement factor H98,y2 ~ 1, which would otherwise be degraded by reducing the pedestal confinement were a higher rate of D2 gas fuelling used instead of the pellets to mitigate the W contamination. The causes underlying the improved performance and energy confinement obtained using this combined, gas and pellet fuelling scheme is investigated here in some detail.

Collection:
Journals
Journal:
Nuclear Fusion
Publisher:
IOP (Institute of Physics)