You’re ignoring two things. First the x-ray emission goes up as the charge of the ions squared–that cools the plasma. Second, the reaction rate and fusion power generated at a given temperature goes down rapidly for heavier elements. So pB11 is best. Stars can fuse heavier elements because they are so large the x-rays can’t escape the core. They also take billions of years to burn the fuel–not ns as in the DPF.
