This sounds significantly more feasible than nuclear pulse propulsion ("project orion" style) which I used to think was the only feasible approach to get to another star.
One thing that was unclear from the paper to me: How does the fusion drive "pick" D/He3 fusion over D/D? Can this be "forced" by just cranking the plasma temperature way up? Or do you still just have to deal with a bunch of neutrons from undesired D/D fusion?