Overview
Going up in temperature increases a phenomenon called breaking radiation (Bremsstrahlung). It happens when some of an electron's kinetic energy is converted into X-rays. Directly capturing this radiation and turning it into current is possible; experimental results show up to 80% efficiency.
The hydrogen boron reaction requires temperatures over 1 billion Kelvin, where bremsstrahlung dominates the plasma's main energy loss. Due to the aneutronic environment, direct loss recapture is less complicated to integrate into the reactor's design.
Overcoming direct loss recovery is a giant leap forward in reaching commercial fusion.