> A krytron. A gas filled cold cathode trigger tube, containing radioactive > material used to detonate a nuke. > >
They use Nickel-63 (a beta emitter) to keep the gas ionized so the switching jitter is very low (hundreds of picoseconds, IIRC). I actually designed these into a circuit once when I was a lab tech while I was in college. They asked me if I could build this bizarre pulser that ramped the voltage from 2kV to 6kV quadratically, it was going to be used in an electron gun, with the idea that the rear of the electron beam would be going faster than the front, so it would self-compress as it propagated. I said I could build it, and started cracking books to figure out how. It turns out they didn't really believe a kid without a degree yet would be able to build such a device, so they gave the same assignment to a grad student. I used a shaped transmission line as a storage element and the krytron as the switch. The transmission line assembly was pretty large, but the switch circuitry fit on a teeny board about 5x5cm. Risetime was about 350ps. The grad student's effort occupied a much larger board, about 40x40cm, with this long chain of avalanche transistors doing the switching. His took about ten minutes to get ready between pulses, and it would pop a transistor every few hundred pulses. While I was testing mine, I was running it at a few hundred pulses per second, for hours at a time. I never had a failure. I probably still have a couple of krytrons. > A few years back, Westdave had just visited his cardiologist, the day before > the TRW swapmeet. He had an exam, that required ingesting some radioactive > "juice". At the swapmeet, a vendor was selling a working geiger counter. Dave > lit up that puppy. > > That must have worried/intrigued the onlookers! You don't get an opportunity like often. - John -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/58A7FDBF-3DB9-45A6-AD3C-30EB90E0384B%40mac.com. For more options, visit https://groups.google.com/d/optout.
