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: A well spent Saturday
Date: Mar 21, 00:56 am
Poster: Richard Hull

On Mar 21, 00:56 am, Richard Hull wrote:


I spent about 2 hours readying the fusor for a timed run. The preparation was one of continuously pumping the system and glow mode cleaning until 20Kv could be reached in air.

Next D2 is admitted and allowed to purge the chamber of most of the air.

A delicate balance of flowing D2 versus pump valving is needed to not squander D2, but fill the chamber adequately while remaining at only about 1 micron. (real tricky! Took me an hour to hit this spot).

Next the power is slowly brought up until I hit 19KV and the timer and neutron counter are started. A lot of fine control is needed on the power variac to hold the current at ~10ma, though at times during the run, I was at 5ma for short periods and also as high as 20 ma, again, for very short periods. The voltage ran from a low of 19kv to a high of nearly 24KV. Definitely at 24KV the neutron counter was moving out at over 1 pulse per second (scary).

Both Scott Little and I agree, flowing D2 is usually better than a valved off chamber charged with D2. Also, I can just barely detect above background counts near 15KV, but the 10E3 n/s region demands about 20KV operation and a minimum of 5ma.

The results of today's run was 2.6X10E4 n/s!!
This is a landmark run. I blew my diodes when a huge discharge arced across the capacitor in an attempted second run. Gotta' fix the supply before another run.

Learning from all this.....I find:

1. A 6" fusor is nearly a perfect size in tradoffs between moderate pumping and D2 filling costs
2. One should provide an insulator for at least 30 KV in air on such a system.
3. Home made supplies for this sized work should be made with huge air clearances or sunk in oil.
4. Have both good valves on the chamber and a superb gas input metering system. (my valve is excellent and the D2 metering valve adequate.)
5. Have a friend on hand for serious experiments to assist in non-critical but necessary chores during a timed run.

Richard Hull