Hi All

Here's a news bite from "New Scientist" that I had to post on...

http://www.newscientist.com/news/news.jsp?id=ns99994049

... basically DoD is researching mini-nuke warheads that don't use either fission or fusion but instead use metastable nucleii of hafnium (or other elements) that are "de-excited" rapidly by x-ray emission and release a flood of gamma-rays. Potentially a gram could pack the punch of 50 kg of TNT - that's 200 Gigajoules per kilogram. Such "micro-nukes" could whack tanks or aircraft in a single shot but via much smaller warheads. Or imagine future Navy railguns killing ships with a single shot.

Currently meta-stable hafnium is made in micrograms by bombarding tantalum with protons, but eventually it could be made from regular hafnium that has been "pumped up" via soft x-ray lasers or ramped-up x-ray generators. Personally I think it's a ridiculously expensive way to make a warhead, but it'd be a very effective way of making a much cleaner nuclear-pulse vehicle. If an effective way of thermalising the gammas can be packed into a pulse-unit then theoretically you could boost to orbit with it. A maximum exhaust velocity is ~ 648 km/s, but channeling the atomic debris usefully will be tough. Maybe it can be used as a superbattery to energise a reaction mass to ~ 50 km/s or so?

Still the hysterics about the weapons potential might kill the research before an economical way of making pumped hafnium can be found.

Adam