ICRH options for JET-ILW DTE2 operation

Ion cyclotron resonance heating (ICRH) plays an important role in high performance JET-ILW plasma discharges, both for keeping the heavy impurities away from the plasma centre as for increasing the core ion temperature to boost fusion performance. While the former is needed in all high-performance discharges for steady state operation, the latter will be particularly important in the next-coming JET Deuterium-Tritium campaign (DTE2). Currently, the workhorse for impurity control in high power D plasmas is fundamental H minority ICRH (with simultaneous omega=2 omega(c) harmonic D heating), which leads to localized core electron heating that induces turbulence (flatter density profiles) as well as peaked electron temperatures. For fusion power enhancement, dominant bulk ion heating and RF acceleration of the NBI ions to appropriate energies would be preferable and theoretical predictions suggest that ion heating is also effective for core impurity screening. In this paper, we discuss the basic modeling results of different ICRF scenarios available for the DTE2 campaign in JET-ILW, highlighting their main properties in terms of the RF absorption of the various species, their slowing-down properties and their impact on high-Z impurity transport. Correctly modeling the wave absorption, slowing-down and collisional energy redistribution of the simultaneously RF-heated species in a DT plasma mix with important neutral-beam injection (NBI) is numerically challenging and is outside the scope of this paper. The simplified calculations presented here are rather intended to give the reader an overview of the ICRH options for JET-DTE2 with references to the state-of-the-art ICRH modeling given throughout the paper.