Reply To: Stay out of politics

[jamesr]

Not sure about some of your figures there.

Decaborane density is 950 kg/m^3.
http://www.webelements.com/compounds/boron/decaborane_14.html

You quote here the density of solid decaborane – this has nothing to do with the the density of the plasmoid or the average gas density in the chamber.

From http://arxiv.org/ftp/arxiv/papers/0710/0710.3149.pdf
Total input energy in this example is 14.6 kJ, x-ray yield is 9.5 kJ and beam yield is 13.4
kJ, so total output energy exceeds input energy by a ratio of 1.57. Preliminary estimates
indicate that energy conversion of both the x-rays and the ion beam can reach 80% with proper
design, so that net energy production with close to 50% thermodynamic efficiency should be
possible, if other losses in the entire system can be reduced to levels small in comparison.

If total energy output ratio is 1.57 and you can extract 80% of that for electricity then the remainder will ultimately end up as heat in the system somewhere. Whether that’s in the device itself or the surrounding shielding.

If electricity output of a device is 5MW then there will be 5/0.8=1.25MW of losses – ie. heat to dispose of. Even if the conversion efficiency got up to 90% then there is still 10% not being converted which has to end up somewhere. I don’t reckon anyones wildest dreams would think the heat would only be 0.05%

A key challenge as I see it is that unlike in tokamaks where the plasma is kept away from the walls of the chamber, in a plasma focus the plasma will be touching the walls – heating them up and cooling itself down.

In response to Brian:

No, the whole plasma has to be kept quite hot

I guess its a question of how hot. I thought the overall plasma would cool between pulses to of the order of 10,000K and recombine partially. But the electrodes need to be kept under ~1000K.

James