The obstacles to exploitable fusion will not be overcome. There, I said it, I own it, come back and beat me with it if I turn out to be wrong.

In order to see this, by way of contradiction, suppose a stable, sustained reaction.

1. How much of the heat is exchanged, and how is the rest dissipated? (How would you design a conventional steam generator if the ignition temperature of coal or gas were millions of degrees?) 2. How refuel? (Stars don't need to refuel: how far down does that scale?) 3. How small a breach of containment would destroy the apparatus?