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Author: Subject: Marx generator pumped vircator-single-shot? or otherwise?
tsathoggua1
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[*] posted on 20-3-2017 at 05:35
Marx generator pumped vircator-single-shot? or otherwise?


The title of the thread says most of my question. Are virtual cathode oscillators single-pulse shot only devices, like for example, EPMFCGs (explosively pumped magnetic flux compression generators). The latter carries little interest for me, aside from learning from extant data for the sake of obtaining knowledge, since they are nondirectional and broadband EMP devices and thus nondirectional and causing collateral damage rather than a directional EMP/HERF emitter. But something like a vircator coupled to a waveguide and pumped by a heavy-duty marx generator or cockroft-walton could be fun to play with (in the right sort of area of course, with nobody and no electronics bar targets deliberately placed there around and protective clothing)

The virtual cathode oscillator seems like it might well be a one-pulse device requiring custom-built 'shells' to be cyclically coupled to, fired, and ejected from the power supply in a conceptually similar manner to a revolver, pump-action shotty, or minigun (albeit the latter aiming somewhat above practical charging rates) but the general principle of one shot, rotating to, or pump-loading a new vircator 'cartridge' or caseless-round-like belt fed unit tuned in terms of rotation rate to operate at the charging rate, that is to say, one charge, one rotation of cartridge)

Are these electronic devices one-pulse and then burnout or are high energy vircators single shot only? or can they be made multiple-pulse by means of a refractory metal grid, or carbon grid in the vacuum chamber?
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jpsmith123
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[*] posted on 21-3-2017 at 06:22


As I understand it, the main problem with "vircators" is their low efficiency. With the possible exception of some coaxial type designs, I believe that most have an efficiency (electron beam energy to output RF energy conversion) of only a few percent.

I would guess that most of the energy is dissipated in the anode, so it seems that repetitive operation is possible but with a duty cycle limited by the ability of the anode to dissipate heat; sort of like an x-ray tube.

Here's a thesis paper I found regarding a Marx generator driving a vircator and the picture on page 81 shows damage to the anode screen.

https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/18922/Ye...
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tsathoggua1
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[*] posted on 16-4-2017 at 11:56


I was thinking of the coaxial type. I was under the impression that they were ideal for generation short to ultrashort duration, high-intensity MW pulses.

I was more wondering if at high energies, the anodes would survive repeated, single shot pulses, or if operation with a marx generator or CW array and transformer would just ablate the anode, like in an exploding bridgewire. Presumably, use of higher-MP/BP temp metals for the anode would allow greater durability, if say, using something like tungsten, molybdenum or iridium.
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tsathoggua1
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[*] posted on 17-4-2017 at 01:13


Thats a really interesting paper. Thanks a bunch. Although I can't see it very clearly atm. Something like welder's eye, and its excruciating/

Excise any typos today,, I'm going solely by touch typing without looking at the computer screen for more than a few seconds at a time..

[Edited on 17-4-2017 by tsathoggua1]
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Sulaiman
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[*] posted on 17-4-2017 at 05:51


I have no experience in this area but I guess that;

a single high energy pulse of pre-settable energy would be best
because if a series of small pulses were equivalent
then no one would need a high energy version :)

Pre-select energy discharge level based on experience ;)




CAUTION : Hobby Chemist, not Professional or even Amateur
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