Exactly. But how do you power the fusion before tapping into it to become self-sustaining?

@Petter High power impulse lasers. It is amazing, in the excitation phase, just for a few thousands of a second, a Tokomak needs the energy of a city of a few hundred thousands people!

@zesty I know. One of the military's problems is how to produce rapidly repeated bursts without destroying the lasers themselves. The modern day equivalent of cooling the barrel of a machine gun!

Powered by a small reactor, as used in satellites?

@Petter I don't think that satellites use reactors in the traditional sense. It is just way too heavy - critical mass of the fission material plus shielding for the electronics. Also, there is a huge problem of contamination if something goes wrong.
In some, military, satellites the energy source is thermoelectric fueled by isotopes.

@zesty True. Unfortunately, we can only speculate.

@zesty @Petter Your conversation got me curious and spent the last hour reading about how Thorium would be a poorer option than Plutonium for spacecraft and satellites. Interesting reading, Thanx guys!

@JazznBlues My pleasure, probably @zesty's too.

@JazznBlues, @zesty Just a piece of thought-fodder.
The incandescent lamp was the first efficient device for creating light from electricity. It's a pretty "hammer it" solution, in that it simply heated a filament until it glowed brightly, generating far more heat energy than light energy.
Then it was discovered that an electron beam, which mainly emits ultra violet light, could be made to fluoresce and tubes with fluorescent coatings were produced. These created 4 to 5 times more visible light than incandescent bulbs.
Then quantum theory gave rise to the Light Emitting Diode, which is twice as efficient as a fluorescent tube, contains no mercury, and involves simple circuitry.
Now:-
Nuclear fusion was at the 'hammer it" phase from the 1950s. Now it is at a phase where the hammer is smaller, but is still a hammer. Will future discovery lead to a way to directly insert an extra neutron into Hydrogen atoms, then persuade them to pair up whilst releasing quanta of mass. (energy)

@Petter Sure, LED-s are more efficient. There is a problem, not solved yet quite well. The light spectrum of an incandescent lamp is "white", consists all the frequency components of the visible range with more or less equal weight. This is the best for our eyes. The fluorescent light and the LED-s emit the whole energy just at a few frequencies. Hence they are mostly monochromatic. Coatings help but the output is still an uneven spectra.

@zesty The bloody phone posted my comments in mid-write. That's why I prefer my desktop machine, but I'm 1500 miles from home. The post is now fully written.
The preamble was basically to present the analogy. Controlled fission needs to find a more elegant means of stimulation. (So do most men, but that's a different subject!!!)

@Petter Stimulation for controlled fusion? Interesting! Hmmm...

@zesty Perhaps, one day, given the advances in quantum theory ..... Who knows?
I love subjects like this.

@zesty Imagine man being "one up" on the sun.

A strong possibility, but a powerful fission source would tend to have a long lasting effect, rather than a brief spike. I bet the boffins in both the USA and UK are puzzling over every bit of information they can glean.