This article talks about a different way to create power from fusion reactions:

Micro-Fusion For Space Propulsion and Weapons with Gigavolt Super Marx Generator, Proton Beams or Argon Ion Lasers

The first idea uses a “Super Marx Generator” to create extremely high voltages. According to the artcile:

A “super Marx generator” ultimately reaching gigavolt potentials with an energy output in excess of 100 megajoule. An intense 10 million Ampere-GeV proton beam drawn from a “super Marx generator” can ignite a deuterium thermonuclear detonation wave in a compressed deuterium cylinder, where the strong magnetic field of the proton beam entraps the charged fusion reaction products inside the cylinder.

As you read into the article it all begins to sound like fantasy, but there is one interesting thing: The Marx generator. It is interesting because people build Marx generators in their homes fairly regulary. Here is one generating 180 Kvolts:

And here are complete instructions for builing this Marx generator:

180kV Marx Generator

From the article:

A Marx generator works by charging the capacitors in parallel via resistors, and discharging them in series. Once the capacitors have charged enough the first gap will breakdown, and the voltage across the two capacitors will have doubled. Since the resistance of the ionized air in the spark is much lower than the resistance of the resistors the capacitors are effectively in series. The next gap will breakdown immediately due to the increased voltage across it’s gap and this chain reaction continues up the ladder. The voltage across the chain of capacitors will be the sum of all their voltages, and enough to spark to either ground or another Marx generator if in a bipolar setup.

Scale up this basic idea and you can create incredibly high voltages.