But it sure has the, ahem, potential to be nasty.
I think the chances of catching a stray 400kV electrical hit are hopefully small. Keep one hand in your pocket when working with EHT is a good policy. (Not holding your nuts though) Good chance stray HT might screw a few instruments though. However, because of the (probable) impossibility of getting useful data out of a system running a permanent 400kV plasma-arc the plan is to use the arc in bursts only.
BTW, someone earlier in the thread asked about Quartz tubes with plain end-caps.LFH have just put into stock some low-cost 130X10mm Quartz tubes with a 2mm wall thickness. We also have plain fittings for them, or can engineer any extra fittings (tubes, valves etc) for the end-caps you fancy.
axil. Thanks for the link- I had read the Klimov paper but some time ago - a useful reminder. I note he was also using Nickel Electrodes. I have plenty of lead shielding, and good Beta/Gamma/X-ray detection. Unlike Klimov and co though I wont be adding copper and iron to the fuel- but more on that later.