Hello from Kansas, USA! (and two questions)

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Brendan_Murphy
Posts: 8
Joined: Tue Jun 30, 2020 10:43 pm
Real name: Brendan Murphy
Location: Kansas, USA

Hello from Kansas, USA! (and two questions)

Post by Brendan_Murphy »

My name is Brendan Murphy, I'm 20 years old and studying electrical engineering at Wichita State University. I am currently in an internship at an on-campus laboratory and since there's very little human contact compared to other places did not shut down so during this pandemic I've had both the time and money to start working on a fusor!

As soon as we were kicked out of the dorms (I'm still currently working despite that) I immediately started designing and working on parts for my fusor. (TIG welding is also a hobby for me so this was very helpful in the manufacturing process) In the beginning it was going very smooth because at that point I thought the most complicated part would be the vacuum chamber. Which I have now completed and with just a cheap mechanical pump can take the chamber down to 35microns.

I assumed that the HV electronics bit would be easy for me and I kept telling myself that “I'll cross that bridge when I get there”, I COULD NOT HAVE BEEN MORE WRONG. First thing that I found was a fantastic bog standard .9 KVA 15kv old neon Transformer (With no fancy GFCI or anything like that). I also found HVDC (up to 40kvdc) test probe with a meter already on it, because after starting to design one I realized that buying that would be much safer, save time and confusion.

My first thought was to power the transformer using my 3kva variac then wire the transformer output directly into a Bridge rectifier with some 30kv rated diodes, Did not work. Then I thought Instead of a bridge rectifier I wire it to a voltage multiplier that I created using some 6KV rated diodes & capacitors, that also didn't work. I realize that voltage multipliers enjoy higher frequencies than 60hertz, I knew this at the beginning but I was hoping it wouldn't be such a problem. So now the set up I have now is a cheap neon sign power supply (Powered from my variac) that then outputs some high-frequency (my guess is around 20kHz) at around 5kv into voltage multiplier (3 stages) with 30kv rated diodes and capacitors. This is only somewhat worked. It was at this moment when I achieved my first plasma in a vacuum and also realized my feedthrough that I purchased 2 months ago is not sufficient and earlier today I ordered a much more sufficient 30kv rated feedthrough (Couldn't find one 2 months earlier). I am still not convinced that this method of getting HVDC will work though with little amount of testing that I've done so far.

And so now I finally decided to create an account to share what I've done so far. I am hoping to hear what others have to say about what I've done so far, and would very much love to hear any suggestions that could help me along the way.

At this moment I have two questions:
First, what is the most common method or methods that people commonly use to generate high HVDC for a neutron producing fusor?
And second, I keep getting polarities confused, Is it ground/chamber that needs to be positively charged (And would that make it the cathode?). And the grid inside the chamber needs to be negatively charged? (And that make it anode right?). I currently have positively charged and I'm not certain that that is correct.

Thanks, I'm looking forward to this project and I've already gained lots of Knowledge from reading many of the threads here. Looking forward to what happens!
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Richard Hull
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Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Hello from Kansas, USA! (and two questions)

Post by Richard Hull »

Wiring diagrams with polarities are found in the FAQs in the electrical power forum a are metering circuits and suggestions on power supply fundamentals. Read them and study them. The fusor outside metal body is the anode and is connected to a hard ground connection. This means any power supply must have its grounded chassis be positive terminal of the high voltage supply or the zero point at ground. The central grid electrode is connected to the deadly hot high voltage negative output. Almost no supply is ever made this way. As such, the fusor supply is usually an amateur constructed supply. Few living beings are up to the task of hand crafting such a supply. The supply for a neutron producing fusor is not about hot negative high voltage with reference to ground. Any good high school student can produce negative 30,000 volt DC supply.

The neutron producing, (true fusing), fusor reactor is all about voltage and current or Power! This kicks the high schoolers, for the most part, out of the running. A fusor might demand between 400 to 700 watts of continuous high voltage, input electrical power. If we hit the middle figure of 550 watts demanded, the current that must be had at 30,000 volts is 550/30,000 =.018 amp or 18 ma! Thus, a supply capable of a full 20 milliamp delivery is absolutely demanded at a minimum! The voltage must be capable of being brought up from 0 volts to 30,000 volts very smoothly. The fusor at turn on might demand 40ma for a second or so before it settles back to the 18 ma run current.

Commercial supplies are available for about $4,500 that will satisfy this demand. The fusor supply has accounted for hundreds of people from ever doing fusion with their folder on the project marked "FAILED"

Read all the FAQs in all the forums especially the power forum and construction/operation forum.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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