Fusor Forums

About four weeks ago my chamber was finished but I have not been able to post anything until now due to a trip to South africa.

The chamber was built and welded by a local welder for 430 dollars and the welder was used to weld vacuum chambers like mine since he used to work for the nearby electron accelerator facility. I am actually quite happy with the result and thrilled to try it out.

I am currently looking for a nice feedthrough but for now I will probably drill a hole in one of my cf flanges and put a sparkplug in there, as I have seen others do.

The University of Lund have told me that they could lend me both neutron detectors and Deuterium gas for my project which is great and will probably save me alot of time and money.

For now I will still use my weak flyback transformer until I find a transformer good enought for fusion. The university have several powerful hv transformers but unfortunately they can´t lend me any of them due to the risk.

Happy New Year,
Fredrik Parnefjord Gustafsson

Fredrik,

Nice job...look forward to see more..

Steven

Awesome!

Where did you get the parts? Or did the welder make it from scratch?

A gate valve between the diffusion pump and the chamber would have been nice to see here..

Without some way to restrict the vacuum, precious deuterium gas will be wasted.

Something to consider...

Steven

I see that Veeco Diffusion pump, and it's the very same one I use. Great little pump. Some data points are, that it takes 20 minutes to warm up, and top temp is about 240 degree's F. and you want to use Dow Corning 704 oil in it. You can get it through Kurt J Lesker in 500ml bottles. Start with 100 ML, and add in 25 ML doses as needed. When it kicks in, it will take you right down to 1 micron in a hurry. You need to start thinking now about a valve between it and your chamber or you will burn through D2 faster than you can believe. You want to be able to shunt that main chamber almost closed, and then just barely drizzle D2 into the chamber to reach about 5 to 10 microns.
Happy fuseing

Carl G

As you have stated the valve between the diff pump and the chamber seems to be a good idea, I have noticed that (as you said) 20 min after the diff pump heater is turned on the pressure drastically decreases and it takes barely 1 minute for the plasma to extinguish. The problem is that the flange is custom made for the diff pump flange and I will therefore need to build some kind of adaptor or find a valve with the right flange size, ether way it will be expensive.

Since I can´t afford it right now I will find a temporary solution like placing something between the inline baffles which will increase the pumping time but in turn will save me some deuterium.

Fredrik PG

I used a diy baffle before I got a valve for setting the pump speed, it works quite well (although of course it's a pain that it's fixed). I found around a 2mm hole to be about right for my small diff pump

here's an idea for a restrictor - use the iris from a camera lens ... An Old lens can can be had for pennies. Build the iris into a flange with a simple o ring sealed rod to actuate it.
Lens irises have a fantastic turn down ratio. f1.5 to f16 in fact .