[X] My Assistant

[Guest_DonPMitchell_*]

OK, I'm in that unpopular camp that believes that the Breakthrough Propulsion Program should never be funded again -- we should not spend any money on Heim Theory, gyroscopic antigravity, space elevators, antimater engines, Bussard ramjets, black hole engines, UFO research, and zero-point energy. I have a radical alternative proposal.

Instead of using Wired Magazine physics to get to the stars, I'd like to use The Feynman Lectures physics to get to the stars. I propose building a craft powered by atomic fission. The engine would be a high-current linear ion accelerator, consisting of a superconducting niobium cavity resonator like this one, to get a nice healthy relativistic exhaust velocity.

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Next, we crack open a good book, like Taylor & Wheeler's Spacetime Physics, and figure out how long it would take to get a real spaceship to Alpha Centuri. What is the relativistic form to Tsiolkovsky's Rocket Equation? (OK, T&W does that for you) How much Plutonium would it have to carry? How much ionizable reaction mass?

I guarentee you, this hypothetical ship will get to the nearest star long before anyone invents a warp drive. Maybe I should ask NASA for $1.6 million, to develop this idea?

[Guest_DonPMitchell_*]

It's interesting that 86 percent of the energy from a fission event is carried away by charged particles, mostly the large fission fragments. Being charged, they can be moved around somewhat by electromagnetic field.

Whatever became of the fission fragment triode? Wasn't that supposed to be an extremely efficiently means of converting nuclear energy directly into electricity?

[ugordan]

It's interesting that 86 percent of the energy from a fission event is carried away by charged particles, mostly the large fission fragments. Being charged, they can be moved around somewhat by electromagnetic field.

The problem with fission fragments is their very large mass. Something on the order of 100 a.u. This gives a very poor velocity compared to the immense energy the nucleus has (something like 80 MeV on average). It would be much more feasible to use this to heat smaller molecules (like the H2O proposal before) than to collimate the nuclei themselves as rocket exhaust.

[Guest_DonPMitchell_*]

The problem with fission fragments is their very large mass. Something on the order of 100 a.u. This gives a very poor velocity compared to the immense energy the nucleus has (something like 80 MeV on average). It would be much more feasible to use this to heat smaller molecules (like the H2O proposal before) than to collimate the nuclei themselves as rocket exhaust.

But in the context of intersteller travel, I don't think any kind of thermal expansion of gas can hope to achieve the relativistic exhaust velocities you need. Schemes like Orion also essentially use the fission fragments directly for exhaust. But if the fission-fragment triode can be perfected, to make electricity efficiently, then I think high-speed ion drives might be appealling.

The kinetic energy of fission fragments are around 170 MeV. I bet even for Strontium and Krytpon nuclei, they are booking along pretty fast!

[ugordan]

The kinetic energy of fission fragments are around 170 MeV.

Yes, the total kinetic energy of both fragments. I was implying the average energy of one fragment.