there are so many factors.
your basic p + B11 –> 3 alpha + 8.7 MeV is a lot of energy.
the reaction needs at least 50 keV and is best at about 600 keV;
a fraction of your plasma reacts in the pulse;
you want your magnetic fields to be strong enough to inhibit bremsstrahlung losses (gigagauss fields);
you want your exit beam to be tightly focused and heading in the right direction;
you have to keep your plasma hot and your anode cool;
and you have the energy transformation.
all these things need to be optimized systematically
