Some Hard Sci-Fi Questions

[CharCamOlson]

I write science fiction and would be very grateful if some people in the know could answer a few questions for me on Focus Fusion and possible (possibly distant) applications.

First, what would happen if you took the particle decelerator off the end of a 5MW DPF and pointed the particle beam at something like a tank (possibly shooting through a plasma window to maintain a vacuum in the reaction chamber, providing additional acceleration with a short section of LINAC, and/or neutralizing the beam with an additional electron beam provided by a small cyclotron.)?

Second, assuming an ideal Focus Fusion generator, how much of the power output comes out as heat? Which is to say, in a system like a spacecraft, where getting rid of heat is critical, how much of the 5MW from a 5MW reactor is going to try to cook my astronauts?

Third, if a running Focus Fusion reactor (5-20MW range) is breached (by, say, an anti-tank kinetic penetrator), what would happen? Explosion? Just some toxic vapor?

Fourth, how practical would it be to shoehorn a Focus Fusion generator into something the size of an M1 Abrams Main Battle Tank?

Thanks for any wisdom.

[Lerner]

Ion beams do not do well in penetrating the atmosphere–they are stopped very quickly. As people pointed out in the Star Wars days, there are lot of problems in using them in space as well–earth’s magnetic field for one.
>
>
> Second, assuming an ideal Focus Fusion generator, how much of the power
> output comes out as heat? Which is to say, in a system like a spacecraft,
> where getting rid of heat is critical, how much of the 5MW from a 5MW
> reactor is going to try to cook my astronauts?
About equal, around 5 MW. Getting rid of the heat is the biggest problem for space applications. Since cost is less of a consideration part of the heat might be used for power, which on earth would drive the capital cost way up, but might be less massive than the heat radiators.

[Lerner]

Third, if a running Focus Fusion reactor (5-20MW range) is breached (by, say, an anti-tank kinetic penetrator), what would happen? Explosion? Just some toxic vapor?

No explosion. Yes, there would be toxic vapor although not much. Radioactive methane–disperse very rapidly and very short half life.

Fourth, how practical would it be to shoehorn a Focus Fusion generator into something the size of an M1 Abrams Main Battle Tank?

Anything that can power a truck can power a tank. Anything that can power a ship can power a warship. It would fit in anything truck-size or large, not a car.

However, as a weapon itself, we say the only way it could be used is to drop it on someone. 3 tons of cement would be much cheaper.

[Lerner]

Some sci-fi ideas with FF–what if we could get to Mars in two weeks? Jupiter’s moons in a month? How would that change manned/unmanned exploration?

A multistage Saturn-sized FF rocket could get a small payload to 1/3 the speed of light. Proxima Centauri in 15 years or so–shorter than many of NASA’s projects start to finish.

Reasonably sure at that speed you can use interstellar magnetic fields for breaking so that reduces fuel needs–only acceleration and maneuvering at destination, not deceleration.

[CharCamOlson]

Have y’all corresponded with any of the Mars mission initiatives? It seems to me getting to Mars in two weeks and then having plenty of energy on-site (as well as heat, which is a hassle in space, but really useful on a giant iceball of a planet) is a game changer. I know someone mentioned that somewhere in the forums.

Rapid, efficient space propulsion would also make asteroid mining much more feasible, which would be a REAL game changer.

Heck, being able to get 5 MW out of a three-ton generator for 5 pounds of fuel a year would probably make getting out of our gravity well much more feasible, which would make everything else in space immensely easier even if the reactor could only work doing that.

[Breakable]

I would trust that as a fusion-for-peace collaborator Eric does not appreciate the idea of a DPF being used as a weapon. Certainly military capacity does not necessary mean more war, however I agree that having a large amount of power is a military capacity in itself – imagine a warship armed with a few rail-guns:
https://www.youtube.com/watch?v=r_yUNm8Tl9o
or otherwise high powered laser weapons

However I would think in a book of more fiction than science you could image shooting a huge plasmoid at a high velocity into a target and expecting it to explode in a fusion reaction that would also release a large burst of xrays as dangerous radiation. This would probably be a high rate of fire weapon and in terms of operating environment it would be easier to imagine it working in space, however due to ball lightning “myths” it might be possible to explain it working in atmosphere.

[Author]

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