Demo fusor pluss construction

[Johannes Wagen]

Hi, I am Johannes and I am 21 year old from Norway.
I have been reading about fusors and acquiring parts for about a year now. My plan moving forward is first getting a vacuum system up and running, without a gas system and HV. Then add HV with a simple spark plug feed through to hopefully get plasma. The gas system will be a large enough project in itself, so I have not put too much thought in to it. I however plan on using D2O electrolysis.

The parts I have acquired so far is:
Mechanical vacuum pump, Alcatel CIT 2010

Diffusion pump, CVC 2"
Forline valve, 1/2" ?, on the small side?

Throttling valve, CVC 2"
Oil baffle, CVC 2"

Conflat 4 way cross, 4.5"

Penning gauge, Inficon PEG 100


Now as for the parts major that I am missing:
View port, ebay
Pirani or thermocouple gauge, ebay
Conflat nipple 4.5", ebay
Forline hose and KF adapter, LDS Vacuum
Conflat blank 4.5", HV and measurement port, LDS Vacuum
Various clamps and gaskets, LDS Vacuum

The CVC throttle valve have some special flange that I can't find, so I am forced to make one. I think a 4.5" rotatable conflat might be machined to work. Otherwise I have to machine it from scratch and weld it to a conflat nipple form the main chamber. The pump, valve and baffle all have the same flange.

For measuring the pressure I have got a penning gauge, but I think I also need a Pirani or thermocouple gauge to get good coverage across the pressure range. I plan to make a CF 4.5" to KF 25 adapter, add a tee to it and attach the gauges. Does the extra bit of tubing effect the accuracy of the gauges?

Does this plan sound OK?
Is there some major bits here that won't work or are unnecessarily hard?

Best regards Johannes Wågen

[Richard Hull]

It sounds like you are on your way to making a good fusor project. The extra tubing will not affect the gauges to any significant degree for fusor work. As long as the gauges are attached to the chamber fairly close, that is all that is needed. Good luck.

Richard Hull

[Dennis P Brown]

Very nice. As everyone discovers when they first build a vacuum system - connecting the various parts and equipment together can be a major job in of itself!

Your 4-way cross will make an excellent fusor chamber.

One question - doesn't your Penning gauge cover from 10^-6 torr up to a few torr? If so, a Pirani or similar gauge would not be needed unless you want a fore pump gauge for the diffusion pump's outlet line. Nice to have but not critical. Also, KF-25 is a good size for the vacuum gauge connector.

Remember to ground both the chamber and gauge connector and/or its connector vacuum line so the high voltage plasma does not reach/short to the gauge head/detector.

[Johannes Wagen]

Thanks for the encouraging words!
My penning gauge goes up to 10^-2 mBar. Witch if I am not mistaken is just a hair too low for fusion. Anyway I have already order one so I will have good coverage from atmospheric down to 10^-9 mBar, way lower than I will ever need. I will have about an order of magnitude where both gauges work, between 10^-2 mBar to 10^-3 mBar.

Is it nesesery to add extra ground to the gauge or will it get sufficient grounding form the kf flange?
I will off course ground all exposed metal parts for safety.


Johannes Wågen

[Dennis P Brown]

Grounding the KF flange would, I'd think, be enough. That said, I ground both the KF and the detector sensor on my system but I have huge electric fields near the detector sensor.