Reply To: Great News!

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delt0r wrote: Well no i can’t *because* there are no fast opening switches. In small scale well yea, every switch mode power supply uses inductors and the main energy store which makes them far more compact than a transformer/ripple cap combination. But the physics is straight forward and power density is pretty good compared to caps. Current at the MA level is a little more challenging without superconductors. But then MA is not trivial with caps either.

But if you can get a solid state switch with high current and high standoff. There is a strong case to use magnetic storage rather than caps.

A large slow inductor will not be able to efficiently feed a fast pulse system like a plasma focus. It is better suited for tokameks. Over a decade of effort was put into the so-called plasma opening switch. The idea was to charge an inductive energy store and switch it to the load. The problem with inductors and fast pulses is the coupling. Plasma opening switches have an efficiency limit of 25%. The switch limits the efficiency to 25% when the switch is perfect. Marx technology has an efficiency limit of 33%. Regular RLC banks can do better depending on the match to the load.

Diamond is unobtainable as a practical switch at the moment. The material is mature enough to be used as a switch but the trigger is a problem. Diamond cannot be doped n I believe so you need to trigger it with UV photons, e-beams ,etc. The switch is only on for as long as the photons are present when operating at high voltage stand off. You need a high power UV laser below 200 nm, a flash lamp or particle beam system. The military invested heavily in diamond and it fell on its sword. For someone that’s saying I’m being negative, again, I’m speaking from experience. My employer worked on diamond switching for a decade or more. The trigger is the show stopper right now. A laser could be built to do the necessary triggering but it would be high power and high rep rate. Not a good combination.

SiC holds a great deal of promise but I don’t think it will reach the necessary voltage without stacking the switches in series which is the problem with Si switches. When you run switches in series you run the risk of jitter and the voltage showing up across one switch. A 20 kV switch does not like having 40 kV across it for long. This is the problem of solid state. Gas switches self break above their rated voltage and recover. Gas has not organization to it so who cares if it arcs. In fact, the switches use arcs to carry the current. Solid state switches arc under self break and solid materials don’t recover. There are tricks to avoid this problem but it takes someone steeped in solid state pulse power technology to make it work. Even the masters stay away from high voltage, high current because of the risk and cost.