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"In a recent paper published in Physical Review Letters (PRL) Jérôme Duplat and Emmanuel Villermaux developed a method to generate centimeter-sized vacuum bubbles in water with miniature laser-driven explosions, and observed the flash of light produced as the bubble collapsed a not-fully-understood phenomenon known as sonoluminescence." Amazingly they concluded that the temperatrue inside the bubble as it collapses is about 26000 K. At this temperatures some (not me) argue for nuclear fusion... Intriguing stuff!!! Check the videos! Yet another test for the 'Experimental Physics Stagiare' :-)?

For sure no fusion, that starts appr. from about 20keV, not 20kK. Between both there is still a factor of 11500. What I would rather expect is that the conditions are not appropriate to work with Maxwellian distribution functions. If certain fusion products should be measurable, than this would rather confirm (but not proof) the hypothesis that they do not have Maxwellians but something close to monoenergetic. But most probably they will not measure fusion products, hence no fusion, hence no confusion.

Lockheed Martin Corp said on Wednesday it had made a technological breakthrough in developing a power source based on nuclear fusion, and the first reactors, small enough to fit on the back of a truck, could be ready in a decade.

Is positive news definitely, but when it comes to fusion energy being skeptic is the wisest course of action. On the back of a truck basically means that the energy density of the device is such that the surface energy of a (steady state) plasma is beyond currents materials limits. It is probably a pulsed (ignitor-type) device, which are prone to instabilities. That could therefore refer to their breakthrough claim, of which they hardly say anything though. Lets see

Since there were already a lot of false alarms on the field, one should definitively be careful about it. However not a single detail about its structure or how it works in this new... Here http://www.fusenet.eu/node/400 you can find a bit more of information about it.

is this just another cold fusion crap or something we could have a closer look at .... still not clear to me ... anybody?

So they think they found a way for beta decay to produce both lighter (Ni->Cu) AND heavier (C->N) nuclei? ...

just another attempt to revive cold fusion from the dead ... and all with dubious experimental setups; read the last phrase ""From my perspective, this is still a physics experiment," Zawodny said. "I'm interested in understanding whether the phenomenon is real, what it's all about. Then the next step is to develop the rules for engineering. Once you have that, I'm going to let the engineers have all the fun." He went on to say that, " All we really need is that one bit of irrefutable, reproducible proof that we have a system that works. As soon as you have that, everybody is going to throw their assets at it. And then I want to buy one of these things and put it in my house."

"And according to his calculations, improvements in short-pulse laser systems could make this form of thruster more than 40 times as efficient as even the best of today's ionic propulsion systems that push spacecraft around. "

Dejan please have a look at this also ...

while the nuclear reaction seems to be sound at first view, I am not so sure how this would work: "Electromagnetic forces push the target and the alpha particles in the opposite directions, and the particles exit the spacecraft through a nozzle, providing the vehicle's thrust. "

An exhaustive overview of all possible advanced rocket concepts, eg.. "As an example, consider a photon rocket with its launching mass, say, 1000 ton moving with a constant acceleration a =0.1 g=0.98 m/s2. The flux of photons with E γ=0.5 MeV needed to produce this acceleration is ~1027/s, which corresponds to the efflux power of 1014 W and the rate of annihilation events N'a~5×1026 s−1 [47]. This annihilation rate in ambiplasma l -l ann corresponds to the value of current ~108 A and linear density N ~2×1018 m−1 thus any hope for non-relativistic relative velocity of electrons and positrons in ambiplasma is groundless." And also, even if it would work, then one of the major issues is going to be heat dispersal: "For example, if the temperature of radiator is chosen T=1500 K, the emitting area should be not less than 1000 m2 for Pb=1 GW, not less than 1 km2 for Pb=1 TW, and ~100 km2 for Pb=100 TW, assuming ε=0.5 and δ=0.2. Lower temperature would require even larger radiator area to maintain the outer temperature of the engine section stable for a given thermal power of the reactor."

The problem is not achieving a high energy density, that we can already do with nuclear fission, the question however is how to confine or harness this power with relatively high efficiency, low waste heat and at not too crazy specific mass. I see magnetic confinement as a possibility, yet still decades away and also an all-or-nothing method as we cannot easily scale this up from a test experiment to a full-scale system. It might be possible to extract power from such a plasma, but definitely well below breakeven so an additional power supply is needed. The fission fragments circumvent these issues by a more brute force approach, thereby wasting a lot of energy for sure but at the end probably providing more ISP and thrust.

Sure. However, the annihilation based photon rocket concept unifies almost all relevant drawbacks if we speak about solar system scales, making itself obsolete...it is just an academic testcase.