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[asymmetric_implosion]

The Sandia LTD’s use gas switches and have rise times of 100 ns at 1 MA per module. They operate with +/- 100 kV on the input and give 100 kV on the output with 2:1 current enhancement [Mazarakis, PRSTAB 12 050401 (2009) for 0.5 MA LTD with 100 ns rise, new work was presented last year at the 1 MA level]. The switch lifetime is poor in the SNL LTD and solid state is better in that respect, it becomes a problem of the number of units and triggering the switches. The little I’ve run across on solid state LTD technology is modest currents (100 kA) but it takes many switches per module to get the ~1 us rise times that matter. The voltage is pretty low per module at 2-5 kV. I’m not saying it won’t work but it will require a milliion or more switches. Can you trigger a million plus switches at low jitter? I think so. Can the solid state switches survive the pinch voltage at ~ 3 MA, which is 750 kV to 1.25 MV, when it feeds back to the pulse power (inductively divided of course)? I don’t know. Is the cost of the front end more than the gas switch solution over the long run? Probably not.

I don’t have the ref for it but I am familiar with the work, people use what are called load current multipliers (LCM) on ~1 MA Z-pinches to optimize the matching between the load and the source. The LCM is nothing more than a 2:1 current step up transformer on 100 ns machines. Our PF system operates at 700 ns using a 6:1 current step up transformer. The transformer cores were like $1000 per unit. We use a total of twelve cores. The Thyratron switches we use cost $3500 per unit with another $4K for the controller box per switch. It was a huge cost savings to use the transformer solution and reduce consumables. It fires at 10 Hz as long as the anode can survive. Admittedly, the V-s product for a 3 MA system would be significant by comparison but the cost may not be as bad as you think. The problem again is switches.