DarrellTaylor's Fusor Build Thread

[darrelltaylor]

Thanks for the replies......

I'm planning to upgrade the demo fusor because I want to achieve 'star mode' but I have in the back of my mind my plans to build a fusion fusor, so I want to try to update the demo fusor with parts that I can re-use for the fusion fusor if that makes sense.

To improve the vacuum performance and reach a deeper vacuum I was planning to add a foreline trap with a bellows value either side, and use solid pipe (as per the plans for a fusion fusor). Do you think this will improve the depth of vacuum that I draw or should I start directing these questions into the vacuum dedicated part of the forum?

Of course, I will also ditch the vacuum gauge in favour of something useful. I'm undecided if I should replace like-for-like with a range of 0-100 micron or change to a thermocouple. I think the thermocouple would be more appropriate for the fusion fusor but a like-for-like switch would fit the demo fusors design......

And thanks for the colour explanation - I found the same answer through further re-reading of the FAQ's last night too

Rich - im not sure I follow your logic. The chamber end plates are earthed (via the NST), and the vacuum pump is earthed through the standard UK 3-pin plug. I can happily connect a wire between the fusor chamber end and the vacuum pump and see what happens, im just not sure what it might do?

[Richard Hull]

I would get a thermocouple gauge ASAP so that you will be able to know your vacuum level. It can help find leaks, too.

The general rule is to ground all touchable metal objects in any system. Your system uses the end plates as a substitute for the outer grid normally placed in all demo systems. This is a less than perfect scenario. You have no real outer grid entirely surrounding your central grid. The pump, the chamber body or in this case, the end plates, etc., must be grounded. You are working from the "Make" article and not the recommended path shown to be the normal demo fusor here. "Make" magazine or their website does not do fusion or know much about it. We do.

Richard Hull

[Rich Feldman]

Rich - im not sure I follow your logic. The chamber end plates are earthed (via the NST), and the vacuum pump is earthed through the standard UK 3-pin plug. I can happily connect a wire between the fusor chamber end and the vacuum pump and see what happens, im just not sure what it might do?

Sounds like you got it right, Darrell, assuming a proper 3-pin plug on your NST.

I suggested the experiment because it's trivial to perform. Any change in the "top" plasma would show that your electrical connection between fusor and pump has room for meaningful improvement (in its DC or AC impedance).

Here's an alternate approach. Instead of adding a fat wire, you could start by measuring the DC and AC voltage between metal parts at the two ends of your vacuum hose. Should be less than 1 volt.

[darrelltaylor]

Rich - im not sure I follow your logic. The chamber end plates are earthed (via the NST), and the vacuum pump is earthed through the standard UK 3-pin plug. I can happily connect a wire between the fusor chamber end and the vacuum pump and see what happens, im just not sure what it might do?

Sounds like you got it right, Darrell, assuming a proper 3-pin plug on your NST.

I suggested the experiment because it's trivial to perform. Any change in the "top" plasma would show that your electrical connection between fusor and pump has room for meaningful improvement (in its DC or AC impedance).

Here's an alternate approach. Instead of adding a fat wire, you could start by measuring the DC and AC voltage between metal parts at the two ends of your vacuum hose. Should be less than 1 volt.

I see. The electrical connection is provably less than ideal. Thanks Rich, it gives me another direction to follow-up!