Preliminary considerations and challenges of proton-boron fusion energy extraction on the EHL-2 spherical torus

EHL-2 spherical torus (ST) is one of the key steps of p-¹¹B (proton-boron or hydrogen-boron) fusion energy research in ENN. The fusion produced energy is carried mainly by alpha particles of average energy 3 MeV, which ideally can be converted to electricity with high efficiency (> 80%). However, there exist serious difficulties to realize such conversion in a fusion device, due to the high energy density and high voltage required. To comprehensively describe the progress of the EHL-2 physics design, this work presents preliminary considerations of approaches for achieving energy conversion, highlighting critical issues for further investigation. Specifically, we provide an initial simulation of alpha particle extraction in the EHL-2 ST configuration as a starting point for p-¹¹B fusion energy conversion.