The effects of injection angle on beam-driven ion energization in C-2W

In C-2U experiments, a beam-driven wave was observed to accelerate a tail population of thermal ions [1]. The resulting D-D fusion rate was dramatically enhanced compared to the thermonuclear rate. Since this process transfers beam energy directly to thermal ions, bypassing the electron channel and related loss mechanisms, it would be beneficial to harness this process in a reactor.



The C-2W device has achieved higher plasma parameters than its predecessor (pressure, stored energy) [2]. In experiments with mixed hydrogen and deuterium beam injection, a neutral particle analyzer [3] has observed acceleration of beam-injected deuterons well beyond the neutral beam energy. A recent machine configuration change in which the beam injection angle relative to the machine axis was decreased has created the opportunity to study the effect of injection angle on the acceleration process and to elucidate the resonance condition(s) of the wave-particle interaction. The wave-particle interactions of the two different fast ion populations were analyzed. These data can guide reduced models for the fast ion acceleration process.

[1] R. M. Magee et al., Nat. Phys. 15, 281-286 (2019).

[2] H. Gota et al., 2021 Nucl. Fusion 61, 106039.

[3] S. Kamio et al., Rev. Sci. Instrum. 93, 103516 (2022).