Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Pulsed mode
Date: Feb 25, 11:26 am
Poster: Richard Hull

On Feb 25, 11:26 am, Richard Hull wrote:

>Richard's Fusor III sounds like it's got lots of potential (pun intended) yet to be explored. RH, have you thought about operating the unit in pulsed mode thereby circumventing some of the insulation problems? True, it will be more difficult to determine the neutron flux, but you might be able to boost the system to the interesting realm of 10E7 and beyond where you can do some interesting neutron activation.
>Now, as far as that 100 KV @ 30 ma supply goes...uh, remind me to stay on your good side!!!


Oh yes! From the beginning, in June of 1997, I was pointing myself firmly at pulsed systems as I have a number of hydrogen thyratrons which can easily support 2,000 amp pulses at about 20kv. (that's 40 million watt pulses). I also have a lot of experience with their use and application in Tesla coil systems and other high energy, high voltage circuits.

The fusor might not even require the complication of hydrogen thyratron firing as the device itself would make a great deuterium diode relaxation oscillator. The energy input would be determined by a filter capacitor and the breakover firing voltage of the fusor chamber. The firing, repetition rate or oscillation frequency by a variable series charging resistance. This latter effect was investigated with fusor II extensively using air. Fusor II was no toy! It was a stepping stone and test bed for ivestigating a number of processes. A short segment is to be found on the Introductory fusor video you have made by me where the system is seen to anomolously flash. These pulses could produce current pulses of 20usec duration in the 200 amp range.

You are correct in that neutrons could never be electronically counted during these intervals. Neutron activation would be about the only way to figure the flux and even then only give order of magnitude results. The bursts would be intense blasts of neutrons. The inner grid would be savaged in short order. I have seen pieces of metal ripped from the inner grid in some of the more intense discharges.

As regards insulation break down....WRONGO...Just the opposite! Pulsed discharges of 2us at 20kv with low impedance, (high energy capability), will break down insulation that would easily withstand continuous 20kv DC operation for years!!!! It is at the very core of how a Tesla coil can produce such long arcs and why lightning doesn't need the teravolt potentials calculated to make the cloud to earth leaps! Instead, lightning is merely in the millions of volt range and makes it long trip to ground in a rapid series short microsecond stepped leaders. The leaders heat and pre-ionize the air ahead of the stroke. Such would be the case here too. The insulation would have to be incredibly beefy to pulse a system.

Good to see others with their gears-a-turin on this thing!

Richard Hull