Alex and Ben Haylett are proud to announce that on Sunday, July 22, 2007, they achieved fusion for the first time. Photos will be posted in the Images du Jour forum.
The setup was very similar to that shown in our initial posting:
http://www.fusor.net/board/view.php?site=fusor&bn=fusor_introductions&key=1163102363
but with a deuterium supply system added. It consists of an electrolysis setup similar to Andrew Seltzman’s -see http://www.rtftechnologies.org/physics/deuterium-electrolysis.htmbut unfortunately without his workmanship! The deuterium passes through drierite, a needle valve, 6 feet of .005 in. ID capillary tubing and finally a shutoff valve before going into the fusor.Although a diffusion pump is included in the plumbing, it was not turned on. Our old Leybold D22 is capable of reaching about 1.5 microns cold and about 3.5 microns even when it is hot, so we decided to try for fusion first without using the diffusion pump. We pumped the chamber down to 3.5 microns, then flooded it with D2 to about 90 microns, and then did it again. As the pressure was coming down we turned on the high voltage at about 30 microns. As the pressure dropped further and the voltage rose, we started a two minute count with the scaler, and almost immediately saw a dramatic rise above background. The pressure/voltage was amazingly stable and easy to adjust with deuterium in the fusor.
We are still using a pyrex bell jar, but inside is a stainless “liner” made from a large cooking pot. Inside that is the outer grid and inner grid. The “pot” is upside down, with a 2 1/2 inch window cut in the bottom (now the top). The window is covered with a piece of 1/4 inch thick glass. A Phillips Toucam webcam is mounted outside the bell jar, above the window.
No x-rays can be detected with this setup, even with fusor voltages approaching 20 KV.
Our results follow. They are not necessarily in order, because they were being recorded on a piece of scrap paper. (We weren’t prepared for success on the first attempt!) The pressures shown should not be taken as gospel, because the manometer did not have its own connection with the fusor. (It shared the input used for the deuterium.) The pressure on the pump side of the throttle valve was consistently about 2 microns lower, so actual chamber was somewhere between the two.
Background count immediately before the run(2 minutes each) was 38, 25 and 30. This was from our He3 tube, mounted in the paraffin moderator. Remember that we’re at 3500 feet altitude here in Calgary. The background count after the run (again, 2 minutes each) was 30, 35 and 33 – roughly 16 counts per minute.
We had previously proven to ourselves that the operation of the fusor (without deuterium) had no effect on the count, no matter what voltage or current we were using.
Results (all counts are for 2 minute periods):
V= 13.1 KV I= 12.7 mA P= 12 microns Count: 133
V= 13.5 KV I= 11.6 mA P= 11.6 microns Count: 208
V= 13.5 KV I= 11.7 mA P= 11.7 microns Count: 220
V= 14 KV I= 9.8 mA P= 12.4 microns Count: 271
V= 13.9 KV I= 10 mA P= 12.7 microns Count= 294
V= 14.1 KV I= 9.7 mA P= 12.6 microns Count: 280
V= 14.2 KV I= 9.5 mA P= 12.6 microns Count: 311
V= 14.6 KV I= 9.0 mA P= 12.46 microns Count: 351
V= 15.4 KV I= 8.4 mA P= 12.27 microns Count: 424
V= 15.2 KV I= 8.5 mA P= 12.38 microns Count: 437
V= 15.1 KV I= 8.6 mA P= 12.52 microns Count: 414
V= 15.2 KV I= 8.4 mA P= 12.44 microns Count: 463
V= 15.5 KV I= 8.2 mA P= 12.4 microns Count: 445
In short, our best runs were averaging around 220 counts per minute, versus a background of around 16.
Our He3 detector is the same type used by Jon Rosenstiel, operated at the same voltage, and was about the same disance (12 inches from the poissor) as Jon recently used for one of his record-breaking runs. Jon had a count of about 2500 counts per second with a neutron production of about 1.4e6. Our count was about 3 1/2 counts per second, so we feel that we were producing around 2000 neutrons per second. (Our math is definitely open to correction!)
If our results are satisfactory to the group, we would like to apply for membership in the Neutron Club!
Alex & Ben |