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Re: FAQ - Voltages needed in a fusor

Posted: Wed Jan 22, 2014 6:00 pm
by Peter Schmelcher
The fusor outer conductive shell forms a Faraday cage. Any shell voltage contributes no electric field inside. Ground it.
http://en.wikipedia.org/wiki/Faraday_cage
-Peter

Re: FAQ - Voltages needed in a fusor

Posted: Wed Jan 22, 2014 6:21 pm
by Chris Bradley
An active fusor is not a Faraday cage because it has conductive paths to the outside. Most notably would be the vacuum lines and gas feed, and a conductive arc may bridge the voltage back down to your pumps, gas bottles, and other various attachments such as pressure gauges. In short, something would very likely go 'bang'. Not sure anyone has [been foolhardy enough] to try it. Try it yourself, if you like, and let us know how you get on, but make sure you do it safely, being very very careful (which could be tricky, but not impossible).

Try as hard as you like, I expect you will probably find that the external conductive paths to ground would be much lower impedance than for the internal conditions you want, in other words your high voltage electrons will mostly skip out on playing where you want them to (in the fusor) and find something far more exciting to do on the outside! I suspect in practice any modest power supply would stall and be pulled so low by external current paths that nothing much would happen.

Re: FAQ - Voltages needed in a fusor

Posted: Wed Jan 22, 2014 10:20 pm
by Richard Hull
Your answer is for safety and INSULATION. A hot fusor body or base is a killer. To float a fusor body or base, the insulation would have to be superior and if done would leave a serious health and electrocution hazard to be dealt with. Like drugs..."just say no". Either ground the shell or seek to reverse the diodes in the supply so that you can have a psoitive ground.

Richard Hull

Re: FAQ - Voltages needed in a fusor

Posted: Wed Feb 19, 2014 6:45 pm
by Aidan Kehoe
Quick question: I thought the positive lead was supposed to be connected to the shell or the vacuum chamber. I thought this was supposed to strip the electrons from the deuterium (and, by extension, draw the positively charged deuterium to the negatively charged inner grid). Thanks

Re: FAQ - Voltages needed in a fusor

Posted: Wed Feb 19, 2014 9:48 pm
by Richard Hull
You are still hung up on the idea that a hot lead is always positive (red and deadly)! It could be.... or..... it might not be, depending on how the power supply is made or originally manufactured.

Again........Any premade or purchased, fully ready to use, high voltage DC power supply will have a "hot" lead and a "cold" lead. (the cold lead is almost always connected to ground and metal chassis of the supply.) You cannot use a hard wired, positive hot lead, negative grounded, cold lead power supply on a fusor!

A fusor must have a negative polarity hot or high tension, deadly output lead and this must go to the grid! Such a useful, usable fusor supply will have its positive lead bolted to ground which allows the fusor shell to be grounded and made totally safe to touch! Most all premade HV supplies are positive hot and negative grounded and, as such, are WORTHLESS for the most part. This is why so many fusor power supplies are hand built from scratch.

I feel I made this polarity bit abundantly clear in the original FAQ at the beginning of this overly long and now, much tortured, FAQ thread.

Richard Hull