User talk:LSTech

Off-the-wall questions and desperate thoughts...

Appreciated your recent article, which I still need reread to understand better.

However, as a certified space freak, I have wracked my brains for decades to figure out possible avenues to non-magical very high speed space flight. (Ie, v > 0.1*c, say, which is roughly the threshold for travel to near interstellar destinations in a human lifetime. This also seems to be about the conceivable limit for "conventional" propulsion, like say extrapolations of nuclear energy supplies and ion-drive thrust technology.)

Again and again I conclude that the energy problem is the central issue, and that non-thermal, high-efficiency, and lightweight power handling and energy conversion technology is key. This is what superconducting microwave RF technology might provide.

For example, "photon rockets" as usually suggested seem absurd (thermal disaster, gamma-ray & neutrino losses, etc, etc), but if there were a way to convert anti-matter non-thermally to electric power (eg, some kind of Q-M stimulated transition, connecting a matter-antimatter state with a photon state) they might become interesting. No idea how to do that, of course.

But lately I have thought that superconducting microwave technology might provide one piece of the jigsaw puzzle, that is needed for solution. When I compute the accelerations of just the skin-depth layer in the best superconducting microwave high Q cavities, I got (if I did it right, which is not especially likely) potential accelerations due to radiation pressure at possible fields, that were potentially interesting. (Eg, a > 0.01g for 10 years gives v ~ 0.1c. Aside from low energy losses, such accelerations are important to reasonable trip times.)

Aside from the fundamental energy source, I find myself wondering what the likely ultimate engineering limits might be on the efficiency of, say, DC to superconducting RF power power conversion, and also how to do it in a light-weight structure. Any ideas?

Well, at least the vacuum and cryogenic problems recede a bit. I do think superconducting microwave RF technology is one possible bright spot in an otherwise very bleak landscape.

Anyway, thanks -- nice article. Bill Wheaton, Wwheaton (talk) 17:34, 13 February 2008 (UTC)

Hi Bill, sorry for the very slow response, I was not aware of these wiki "Talk" pages. I have not given much thought to superconductors in space. I would guess a starting point is to estimate the power balance between absorbed and emitted radiation to estimate the equilibrium temperature at which the superconductor would settle, and if that is above the critical temperature. You would have to make some assumptions about black body radiation, even if the superconductor weren't black. This may have been done in reference [2] (Landis) cited in the wiki page Starwisp. I see there is also mention of a superconducting loop in wiki page Magnetic sail, though a similar power balance calculation would apply with the additional power dissipation of the circulating current.

Regards, Eric