Vacuum update

[Papiewski, John]

Dear Fusioneers--

 

I have run the vacuum system a couple times and would like to report it's in good shape.

 

Some details:

1. The thermocouple gauges are good to only .1 torr or so.  They don't indicate any lower than that, though the gauge dials go lower.

2. I was able to get the ionization gauge to come on after about an hour.  That's the more sensitive gauge.

3. After a couple hours of running both pumps I read vacuum in the range of 3-4 E-5 torr.

4. I tried putting liquid nitrogen in also, but did not notice any improvement in vacuum.

5. There appears to be a problem with one of the 3 valves.  If I leave the 'needle' valve open, the system never seems to hit the point where I can turn the ionization gauge on (it needs low pressure to work).  When needle valve is closed, pressure drops noticeably.  When I open the needle valve when the system's at very low pressure, the ion gauge turns off, indicating too-high pressure.

 

6. It would be nice if the chamber's cleaned.

 

According to a recent post on fusor.net, the vacuum we're seeing is well up to the task.

 

More later

 

John P.