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cedric

Wed Sept 29 2010, 02:06PM

Registered Member #2941 Joined: Fri Jun 25 2010, 08:08AM
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Posts: 143

hello every body
I took a look in the archive about this topic and it's Simms that everything then terribly wrong,with quantum bull-sheet and other magical involvement ,

however ,the subject is interesting as it provide a mean to power for instance: copper vapor laser with inexpensive solid state switch,give access to high energy physic experiment.
As I dig into it ,it was easy to understand that the subject relate to electronic with nothing mystic about it ,for instance ,we have all experience core saturation when our dear fly-back was power in to low frequency or to high duty-cycle .
A well design system can reach some megawatt of peak power,and don't involve exotic matter like sos diode and other unfindable high voltage srd rectifier,I will be working on the topic for the next two month,trying my best to extract usable knowledge from Internet and other source to turn it in to a practical design ,If any body out there have technical advise ,it could help,on the other hand I post some of the document I found on the subject...
]magnetic_pulse_compression.pdf[/file]
]magnetic_pulse_compression_layout.pdf[/file]
]magnetic_pulse_compression_nitrogene_laser.pdf[/ file]

plus a very interesting one witch can be found here:

2Spoons

Thu Sept 30 2010, 04:50AM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
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Posts: 615

Some interesting papers - especially the nitrogen laser one. Thanks.

Proud Mary

Thu Sept 30 2010, 09:40AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Here are pics of the Russian TGI-1000/25 ceramic water-cooled H2 thyratron specified to pump the PFN in the N2 laser above. As its name suggests,
this is a 25kV 1000A device. The flange on the anode end suggests it is intended for direct connection into a co-axial pulse-forming line - in a radar modulator originally, I'd guess.

anode end

kathode end

cedric

Thu Sept 30 2010, 11:46AM

Registered Member #2941 Joined: Fri Jun 25 2010, 08:08AM
Location:
Posts: 143

it make sens...

Steve Conner

Thu Sept 30 2010, 02:58PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

cedric wrote ...

hello every body
I took a look in the archive about this topic and it's Simms that everything then terribly wrong,with quantum bull-sheet and other magical involvement

LOL, very well put

The only problem with magnetic pulse compression is that magnetic cores with good characteristics for it tend to be expensive. And also that it attracts those crazy pseudoscience types.

iJim

Thu Sept 30 2010, 04:13PM

Registered Member #2662 Joined: Fri Jan 29 2010, 10:14AM
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Posts: 36

I too am quite interested in this!

I wonder what would be possible with widely available parts?

Something like a 1kV 10us pulse from a mosfet being compressed to a 10kV 1us pulse would be a real achievement.

Most pulse generators I've seen online employing this technology seem to use gas switches and kA currents, is it even possible with solid state devices?

I found some info on the best type of core material:

Jim.

cedric

Thu Sept 30 2010, 04:20PM

Registered Member #2941 Joined: Fri Jun 25 2010, 08:08AM
Location:
Posts: 143

I have been trying few set up with out much success until one hour a go,but it's work ,definitely, with a basic set up I can get the voltage increase by 1/3 and a definite pulse sharpening effect,the induction are made of soft iron from a transformer ,3 plates on top of each other and the one in the middle have few turn of copper tape around it ,the capacitor are made of the very same copper tape and kapton tape,I use a microwave contact switch to dump a capacitor in to the rest of the PFM the scope is set on 50 ohm input with 10ns per division,the rising time don't look to affected by the poor qualities of the inductor...

1285863516 2941 FT97555 Magnetic Pulse Compression

cedric

Thu Sept 30 2010, 04:32PM

Registered Member #2941 Joined: Fri Jun 25 2010, 08:08AM
Location:
Posts: 143

I found some info on the best type of core material:

cool ,I ll have that,,
from all I know there is at list two basic configuration,one witch increase the voltage and one witch compress the current,
it should not be a problem to use it with a solid state switch,that's what I am trying to do...
I try the set up in low voltage because it's a mess to measure the pulse in hv with the scope ,and you need good dielectric all around ,but apparently some people manage to stack every thing on one coax,how cool is that!!!
I suppose the coax is use as a capacitor and some ferrite is place in between the center wire and the shielding at the right place ,
sort of one pass inductor...

iJim

Thu Sept 30 2010, 05:30PM

Registered Member #2662 Joined: Fri Jan 29 2010, 10:14AM
Location:
Posts: 36

Thanks for posting your results, they look interesting.

One question though, in your setup do you think that magnetic compression is responsible for shortening the pulse? Is the magnetic core actually saturating?

Proud Mary

Thu Sept 30 2010, 06:07PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Pulse generators in the nanosecond regime can be built using avalanche transistors such as ZTX415 with pulse forming networks:

ZTX415 application sheet:

This paper has a really juicy ZTX415 pulse generator:

STUDY ON THE CHARACTERISTICS OF THE SUB-NANO SECOND PULSE GENERATOR FOR A PLS ELECTRON GUN
Y. G. Son, S. D. Jang, J. S. Oh, S. J. Park,

Alas, ZTX415 don't grow on trees! But before you leap wailing into the grave, consider using 2N5551 instead. 2N5551 can be bought in hundreds and are as cheap as chips:

High voltage fast ramp pulse generation using avalanche transistor
Liu Jinyuan, Shan Bing, and Chang Zenghu

And this super paper even has a nifty test circuit to identify the most avalanche friendly 2N5551s from a batch:

A fast cavity dumper for a picosecond glass laser
S. M. Oak and K. S. Bindra

This ebay seller has 2N5551 @ Â£2.89/US$4.56 per 100 with free postage. I bought 500 a few months ago, and found them good, and the seller honest.

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