tritium seems to be the fav for Tokamaks, not IEC or polywell devices, many whose goal is to fuse P-B11, boron. This type of fusion creates extremely low numbers of neutrons. And there is a lot of boron.

People pushing p + B11 tend not to notice the losses due to bremsstrahlung from all those electrons.

(basically, electrons "collide" with each other at distance via electric forces, the collisions are largely elastic, but at high temperatures and densities the radiation emitted when they all change their random directions of motion becomes significant)

("bremsstrahlung" is German for "braking radiation")

(when a charged particle is deflected due to electric forces, photons are emitted)

ciao,
Bruce