Reply To: would nuclear energy really be accessible to all?

[Allan Brewer]

I don’t think that graphite/carbon rod/carbon fibre is a viable electrode material because its electrical resistivity is quoted as around 5000*10^-8 ohm.metre compared with Copper 1.7*10^-8, so it would produce orders more heat than the copper electrode. (Graphene itself is a very special case with magically low resistivity.)

Referring back to the calculations on the dominant plasmoid cooling mechanism, I believe bremsstrahlung is being minimised by the design anyway, and it would be X-ray rather than thermal.

jamesr wrote: You also obviously have this hot, few thousand degree plasma in direct contact with the electrode surfaces – this I would expect to dominate everything.

I watched an arbitrary discharge today and it looks like the actual point of contact between plasma and electrode is really relatively small. To get a rough idea, if we have a 1cm^2 point of contact round the electrode (which I think would be an overestimate) and 4000 degree drop in temperature across a 3mm thick electrode we are talking about 50KW conduction – this is encouragingly very small compared to the electrode resistive heating.

That still leaves the bulk plasma thermal radiation for which James was going to try to find an estimate, but that doesn’t sound like MWatts

So its beginning to sound like the dominant source of heat would be resistive heating in the outer skin of the electrodes.

So how about a beryllium electrode to give structure without blocking X-rays, covered with a 20nm layer of graphene for electrical conductivity (to minimise heat production), topped with another very thin layer of metal to protect the graphene and conduct the last 1 or 2 nm to the plasma??