Recently unprecedented high power capacitors were built and tested. A capacitor can deliver more than 10 mega amp to a test sample. The resonance frequency goes over 2 gigahertz and can be increased.
The question is now, if such capacitor can help scientists or the general public with high power electronics, high power laser, fracking, rail gun design, particle accelerators, or has any other uses.
Attached file: https://www.researchgate.net/publication/262376166_2014-May_Sub_picohenry_capacitor_Test_Report
Data 2014-May Sub picohenry capacitor Test Report
It would be extreemely interesting to check the operation of such capacitors in fast dischage circuits for plasam shock wave production.
It would be extreemely interesting to check the operation of such capacitors in fast discharge circuits for the production of plasma shock waves.
Thank you Pavel. Do you mean that shock waves used for obtaining data for EOS?
My experience deals with plasma production by means of the cumulation of cylindrical and spherical convergent shock waves. Currenct derivative of the order of 10^12 A/sec is necessary for the shock wave generation inside the discharge cavity filled by workung gas.
There's more to capacitor life than only the internal inductance. As the initial report may have already stated, you have to worry about the inductance in the connections to the capacitors: if these are wires, even very short ones, they add on the order of 1 nH/cm to the circuit. A multi-MA discharge within 100 ns along such a wire implies a multi-100 kV voltage, so electrical breakdowns along some other path, including inside the capacitor, may well happen. As such large currrents, or maybe rather high current densities and surface currents, your normal materials evaporate and shock and break.
Energy density and maximum voltage on the capacitor are equally if not more important (because, by putting capacitors in parallel you can reduce the inductance at will (well, between limits that depend on your tolerance for finding broken capacitors and fixing them). And, with fast discharges you have to worry about overshoot, which can destroy capacitors big-time.
So yes, fast capacitors are good, but to do it at high currents and voltages isn't easy.
> if these are wires, even very short ones, they add on the order of 1 nH/cm to the circuit
Dear Pereira, wires are forbidden in high speed pulse capacitors.
I agree with you that overshoots must be taken in account in the specifications.
It would be destroyed the capacitor before evaporation of any part if the discharge heats up the dielectrics over its maximum temperature. To avoid that,
dT=E/C/M must be less than (Tmax-Tamb)
Where:
- E=I^2*r*t
- r is the part resistance
- t=discharge time
- Tamb= ambient temperature
- C=material thermal capacity (Joules/kg/ºK)
- M is the part mass
I calculate the capacitor parts to withstand full discharge through a 0ohms 0H load.
Build your own z-pinch?!
https://share.sandia.gov/news/resources/releases/2006/physics-astron/hottest-z-output.html
The Z-pachine is indeed a fantastic piece of equipment, supported by a very good technical and research staff. Remember, though, each shot is something like $ 100,000, in large part because the sudden (0.1 microseconds) appearance of a few 1 MJ in a tiny little piece of material is essentially an explosion equivalent to a kg or so of explosives. In my view it is bordering on dishonesty to suggest that such explosions could be done often enough, and for a low enough price, that you could ever get fusion energy out on a commercial scale. They don't actually say that: the statement has enough plausible deniability (... IF its cause ...., COULD EVENTUALLY ... is an enormous IF and speculation) to be factually true. I've seen many such statements on Inertial Confinement Fusion, and when I have the opportunity I'd say:" ... and if the you had a goose that laid golden eggs you would always have enough gold".
Having said this, I would wholeheartedly support the research with Z and other pulsed power machines at Sandia, including specifically their MagLIF concept for thermonuclear fusion in a z-pinch. Even if you could get one such explosion in the laboratory, which if really successful would destroy a large part of the machine, I would consider this a great accomplishment. Commercially useless, yes (except for the people who make high energy density, fast discharge capacitors), but a great accomplishment nevertheless.
The problem with Z-pinches is that they loose its energy as radiation, so we modified the design for next Pulsotron-300k to heat plasma to more than 300kev.
As curiosity the first z-pinch was built in the eighteenth century by Van Marum:
http://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Electrostatic_generator_Teylers_Museum.jpg/1280px-Electrostatic_generator_Teylers_Museum.jpg
At the bottom of the photo you will see big Leyden jars
The van Marum device is well-known in the community, certainly to all those who attended the 4th International Dense Z-pinch Conference in Vancouver, Canada, in 1997: its Proceedings include a picture of the device.
I'd call the loss of energy from a z-pinch by radiation a feature rather than a problem. It's good if you want the radiation. It's not so good if you want to make the plasma hotter than it would be without radiation. So, you have to increase the power input, maybe on the order of the 4-th power of the temperature increase (if the pinch were to radiate as a black body, which it doesn't).
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