The switch is practical. Ideas like the HCP were turned into multi-channel switches like the MMCS switch that is used in some linear transformer driver systems. They are high current, high voltage switches with very low inductance. The problem is the rep-rate is limited to a few Hz at most.
I think the HCP is feasible to build and test. The key unknown is whether it will be able to sustain fusion as long as the x-ray pulse.
