Exploiting ICRH to maximise the neutron yield in VNS

Abstract While ITER will demonstrate that long duration pulses producing significant fusion power is possible in a fusion reactor relevant environment, the aim of the Volumetric Neutron Source (VNS) tokamak is to offer a testbed for studying the impact of long-time fusion neutron exposure to the plasma facing components. Presently, the auxiliary heating schemes foreseen for the VNS are electron cyclotron and neutral beam injection (NBI) heating while the main fusion power generation is intended to result from beam-target reactions between the fast deuterium NBI ions and the thermal Tritium ions in the plasma. The present paper discusses the potential of only using wave heating to maximise the fusion yield in modest scale fusion reactors. We focus here on ion cyclotron resonance heating (ICRH) while electron cyclotron heating (ECRH) provides the basic target plasma the IC waves couple to. 
More in particular, we exploit the idea that permitted the fusion performance to be boosted beyond what neutral beam injection alone could achieve in the JET DTE2 and DTE3 campaigns. Adopting IC heating at the fundamental cyclotron frequency allows to create a moderately fast ion tail that has a large fraction of particles of a high concentration minority tail near the energy where the D-T cross section peaks, similar to the NBI beam-target fusion scheme. 
Rather than adopting balanced D and T concentrations and count on fusion reactions produced by 2 thermal fuel ion thermal populations, the steepness of the cross section curve is exploited to boost the nuclear reactions between a thermal population and an IC created fast particle "beam".
In the present wave-only exploratory study it is estimated that 20-25MW of fusion power can be achieved when adopting the 2025 reference parameters for the VNS device. More comprehensive study is, however, needed to assess the potential in detail.