Reply To: Great News!

[asymmetric_implosion]

Well, the patent is more complicated than just an arc. That is the simple story. I agree it is a bit overkill but it was granted. To be fair it has to operate in conditions that are not agreeable to the bench top so that is really the innovation.

The size of the caps haven’t hampered the inductance of PF pulse power. A typical cap has a low inductance of 20-50 nH per unit with several units in parallel (~10). The switches are typically the big inductance hogs at 20-300 nH per unit but they are that value regardless of the cap geometry in any practical case. Some large PF systems like DENA have a bank inductance of <5 nH by massively parallel architecture. My three PF devices operate at ~20 nH in the bank with three different types of switches and three very different architectures. In our sources, the switches and caps typically contribute only 5-7 nH (lots of little things in parallel). Most of the inductance comes from bus bars near the load that must accommodate the transition from air to vacuum. It's not universally accepted but the idea has floated around the PF community that you need some finite inductance in the bank to make the PF work at optimum. The value of inductance goes up with current. It does not agree with power transfer theorems but to accommodate certain plasma conditions to confine and sustain the pinch. The inductance relationship I see thrown around most frequently is the pinch inductance should match the axial phase inductance. The bank inductance should match the axial phase inductance. I don't know if this is the true optimum but it shows up consistently over the years since the 1970's. The pinch inductance is going up with current and in most cases the axial phase inductance is going up with current. Therefore, the bank inductance is going up to sustain the ratio. I can tell you this much, the PF-1000 machine has a low source inductance at 1.8 MA and it performs as well as FoFu-1 at 900 kA. By any pinch scaling law, PF-1000 should be up by more than 10X over FoFu-1.

The LVA is a linear voltage adder?? The high current pulse power equivalent is the linear transformer driver (might be same thing with different name). Modules that operate at 1 Hz are currently available with 100 kV output at 1 MA into a matched load. You might need 3-5 of these units in parallel. Sandia National Lab is handing them out to universities for numerous studies. I know U. Michigan and U.C. S.D. have modules. The key questions are the scale up of the PF physics at ~3 MA with source inductance. The LTD is a low inductance source so it might not be able to drive the additional inductance that might be needed to optimize the pinch without significant loss. Time will tell.