Electrode life

[Francisl]

This article indicates that a particular tungsten copper alloy may have the longest electrode life.

[zapkitty]

Francisl wrote: This article indicates that a particular tungsten copper alloy may have the longest electrode life.

… but copper and tungsten are not particularly transparent to x-rays and beryllium is. It’s a heating problem.

I’m sure that LPP would be glad if it turns out they can get by with just copper electrodes for the production units but it seems they are planning on having to use beryllium.

[mchargue]

zapkitty wrote:

This article indicates that a particular tungsten copper alloy may have the longest electrode life.

… but copper and tungsten are not particularly transparent to x-rays and beryllium is. It’s a heating problem.

I’m sure that LPP would be glad if it turns out they can get by with just copper electrodes for the production units but it seems they are planning on having to use beryllium.

How much heat are we talking about? Haven’t you already decided that you’ll need some kind of cooling system for the electrodes?

Maybe when things shift from research to production this will look like a better option.

[asymmetric_implosion]

Materials are likely to plague fusion long after the Q>1 condition is met. X-rays are a problem for the anode but it’s erosion from other aspects like hot plasma (potentially chemically corrosive) and particle beams are also important. A number of researchers have looked at some of the lifetime problems of electrodes. Admittedly, x-rays were not the problem they could be in the LPP pinch but the other lifetime limiting issues are a problem for Be. I suspect a compromise will be required before it’s over. It might be a materials compromise or a lifetime compromise.

I know in our machines that SS304 works well at low current (~100kA), refractory metals work better at modest current (~0.5MA) but you can get by with SS304. Metals like Aluminum are miserable even at low currents. Although Copper works OK, it is inferior to SS304. We aren’t the only ones to observe it. Groups in India, Pakistan and Singapore have published similar conclusions.

[Author]

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