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Microwatt

Tue Feb 15 2011, 05:03AM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
Location:
Posts: 224

i am looking to build a nanosecond pulse generator for 25kv. What sot of circuitry would get me 2-5 nanosecond pulse width and 10kps.

Dr. ISOTOP

Tue Feb 15 2011, 05:12AM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

What is this for?
'Tis hard to switch 25KV at 10 kHz; a thyratron should be able to to it.

Patrick

Tue Feb 15 2011, 05:33AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

A high voltage nuclear weapon trigger system would also work, perhaps you can "liberate" one from the former Soviet Block states.

If you can figure out how to do this with out it costing a whole lot, this could be useful to me as well, though my requirements are'nt nearly that severe.

Adam Munich

Tue Feb 15 2011, 05:34AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

I think a kryton is what you are looking for. They are tough to get though, as they are used in hydrogen bombs.

Patrick

Tue Feb 15 2011, 05:39AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Grenadier wrote ...

I think a kryton is what you are looking for. They are tough to get though, as they are used in hydrogen bombs.

Yes, thats where I would start, but I'm not sure about 10kps as nuc trigs are usually a one-shot deal. If he could find a circuit to start with, and the Kryton, then maybe some "Tube Aces" could advise him?

I'm embarassed to admit Im only vaguely familliar with the circuit princibles of the hollow-state stuff.

Adam Munich

Tue Feb 15 2011, 05:47AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

It's pretty much a hollow-state scr. If he doesn't need the pulses to have a fall time in the sub nanosecond range then he could use a more conventional means of stopping the current flow.

Patrick

Tue Feb 15 2011, 06:21AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

A bit off topic, but just out of curiosity why would a nation like Iran not be able to make a standard Krytron, or at least a primitive one for nuclear initation of a primary?

For a nation willing and able to make everything else that is so special/difficult for Nuclear weapons. Why is a little glass bulb beyond there abilities to figure out, then make?

cedric

Tue Feb 15 2011, 10:05AM

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

Microwatt wrote ...

i am looking to build a nanosecond pulse generator for 25kv. What sot of circuitry would get me 2-5 nanosecond pulse width and 10kps.

2 to 5 ns pulse width is really very short ,gaz filled tube have a typical rise time of 30 ns or more,there is a easy and sheep way to do a ns pulse at up to few khz :by using the so call blumen system from nitrogen tea laser it's possible to get rise-time of 10 nanosecond easily. a sharpening gap (typically a very small gap on the output) can decrease the rise time down to 2 or 3 ns.for the high frequency ,the more easy way to drive a spark-gap in the khz region is to use compress air and to blow the gap,

here is what is left of an early prototype,the resistor or inductor witch was connecting the two plate melted du to missing load to absorb the pulse,this specific pulser can reach about 2khz with 15 kv and feed a 75 ohm coax,the sharpening gap is just at the end of the coax central conductor.it recuire about 5 bar of a small compressor to operate.

this system simple and relatively efficient and I am pretty sure any patent have expire by now but the regularity of the pulse is not as good as solid state.

Proud Mary

Tue Feb 15 2011, 10:25AM

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

Some common transistors like 2N5551 can be made to avalanche and can be stacked to produce high working voltages. We have discussed this type of pulse generator before on the forum, so you could start your forum search with 'avalanche transistor.'

If you Google avalanche transistor pulse generator, and avalanche transistor nanosecond pulse generator you will quickly harvest a big batch of useful guff.

You could start with something like this:

Ash Small

Tue Feb 15 2011, 06:30PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I understand that krytons are not suitable for/capable of high frequencies. Max frequency is only a few hertz. (unless I'm thinking of something else, but I'm pretty certain I'm correct)

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