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: Rudimentary attempt
Date: Feb 03, 1:27 pm
Poster: Scott Little

On Feb 03, 1:27 pm, Scott Little wrote:

Point: I'm a complete FF novice...I haven't even read F's patents...I just got fired up by Tom Ligon's article in Analog...and we happen to have most of the necessary equipment lying around (vacuum system, high voltage supply, etc.)

I've whipped up the crudest pair of grids and put them in a 2.75" Conflat cross. It's relatively tiny...outer grid is 30mm dia...inner grid is 10mm dia. Today I ran it in D2 gas and got a nice-looking glow discharge but the voltage is really low...about 800 volts. Picture available at:


The long stainless tube above the chamber is a He-3 neutron counter.

If I apply more drive to the high voltage supply, the current goes up but the voltage stays around 800 volts...and the inner grid gets red hot.

I tried lowering the pressure and raising the voltage together to nurse the discharge into a low-pressure high-voltage regime. That seems to work for a while. I got up to about 5,000 volts but still no sign of neutrons. At that point, either the pressure falls too low and the discharge goes out...or the inner grid gets so hot that the solder holding it to the Cu lead wire melts!

Any suggestions?