Creation, usage, and destruction of a cathode

For posts specifically relating to fusor design, construction, and operation.
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Enzo Carter
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Creation, usage, and destruction of a cathode

Post by Enzo Carter » Wed Dec 12, 2018 1:34 am

I couldn't find a video tutorial on making a cathode so I thought I should make one and halve others benefit from my creation and mistakes.

Any pointers to make/use a cathode would be helpful.

https://youtu.be/5Tx8ds2M0EY

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Jim Kovalchick
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Re: Creation, usage, and destruction of a cathode

Post by Jim Kovalchick » Wed Dec 12, 2018 11:46 am

Enzo,
It looks like you are learning a lot during your fusor work. I like your set up, and it looks like you want to keep yourself safe. I would like to offer an important safety tip to keep you and others out of trouble. I noticed that you used an alligator clip to fasten your ground to your chamber. Those kinds of clips have a tendency to pop off when you least expect it. If it does when you are applying voltage with your power supply then the chamber becomes dangerous. You should fasten a ground permanently with a bolted connection at both the chamber and at a reliable ground in your lab. There is a lot of information in past posts with more specifics.

Ultimately, you will want to install current indication if you haven't already. That will be the best thing to watch to avoid destroying your grid again. Relying on the view port without a camera means exposing yourself to x-rays when you start using higher voltage.

Good luck,

Jim Kovalchick

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Richard Hull
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Re: Creation, usage, and destruction of a cathode

Post by Richard Hull » Wed Dec 12, 2018 9:08 pm

Very nice setup for a demo device. Enzo is learning that the operation of even a demo fusor requires full time and attention to every detail. He did a great job of fusing his new grid. I like his method of making a simple, yet very effective grid for his demo system.

I am glad dad is around to shepherd the effort. Like Jim said in the foregoing post, a solid ground is a must and once bolted on to the chamber and its plumbing with a heavy gauge wire, you are a lot safer than using an alligator clip with that tiny wire.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Enzo Carter
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I made the forum recommended changes and added a Turbo pump

Post by Enzo Carter » Fri Dec 21, 2018 12:17 pm

thank you for the advice. the power of the forum is more than my fusor might ever generate!!

I added a second ground strap for safety

I am now using the mirror and have the fusor view port pointed away from life forms also added a geiger counter but had no X-rays

i added a turbo pump so i can get the vacuum below the roughing levels. I have an eBay leybold tw 250 that actually works!!!

i changed to a quieter but leaky (oil) edwards two stage 5 that reaches only 76microns. not good but good enough to start the turbo. My Pirani 275 vacuum gage only goes down to 1 mTORR and my new turbo goes much much lower. so a better gauge is needed

here is a video of the new fusor setup, i call it fusor 2.0 as it has the turbo and has changed. but it is still a demo fusor and has no deuterium source.... ....yet.

Also I did some test runs and I didn't melt my cathode! And I experimented with around 15 kV.

https://youtu.be/HBfTcu9lIkI

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Enzo Carter
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Re: Creation, usage, and destruction of a cathode

Post by Enzo Carter » Sat Jan 05, 2019 9:26 pm

I am on winter break and have been working on my reactor and i have done a lot of work by adding a new 70kV power supply and i made a lot of X-rays. i added the new power supply because the 30kV won't output 30kV only 20kV i also did a pump down and pump up test a X-ray test and a voltage/plasma graph.
Enzi_Still_Fusor_XRay_Video_IMG_4981-2.jpg
Here is a video of me planning out my deuterium system:

https://youtu.be/svHzric5t8I

Here is a video of me testing my system for X Rays:

https://youtu.be/Vky4eKYFLzQ

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Richard Hull
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Re: Creation, usage, and destruction of a cathode

Post by Richard Hull » Sun Jan 06, 2019 5:23 am

Enzo,

You need to get that lead shielding in place if you are going to work and sit that close to the fusor. The ideal is to place the operator's station at least 6-7 feet away and use the lead shielding. You should be no closer with all the hand waving that 2 feet from the high voltage terminal when it has high voltage on it.

Remember, the high voltage and the x-rays are the real dangers in fusor operation. I highly recommend a more remote operation station where hand waving motions and you body is a bit farther away from the HV and the x-rays are thinned out a bit.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Bruce Meagher
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Re: Creation, usage, and destruction of a cathode

Post by Bruce Meagher » Sun Jan 06, 2019 6:11 am

Enzo,

I'd second Richard's warnings about the high voltage. You might consider getting a long (3'+) insulating rod to use as a pointer instead of using your hands. Best to train yourself early to minimize the chance of a mistake in the future.

Also for your x-ray experiment what happens when you run this test with plasma? Would you expect the results to be the same? If not, why would there be a difference?

Bruce

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Dennis P Brown
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Re: Creation, usage, and destruction of a cathode

Post by Dennis P Brown » Sun Jan 06, 2019 11:09 am

Richard's and Bruce's advice are sound. I watched your video and your exposure to the un-shielded fusor is not safe. Even if the x-ray threat isn't large, the danger of electrocution is very real. Never place your hands so close to the device.

As for shielding: Lead is toxic and must be painted over at the least. Lead dust is a significant hazard to young children's brain development! All lead creates such dust - hence, the bare minimum is painting over it. Don't ever cut it indoors, and wear gloves when handling unpainted lead. Disposal is an issue since it is a hazardous material and local laws must be obeyed. As such, I would suggest shielding that uses slate tiles. These are extremely cheap, easy to obtain at home depot (as 18" by 18" tiles), are simple to cut to shape with an a dry abrasive saw and besides being non-toxic, are non-conductive! Win-win. Do calculate the required thickness but for under 70 kV, a half inch should suffice. Do remember that edge to edge connections must have sufficient tiles behind that edge to account for x-ray leakage through the joint.

Also, x-rays are line of sight and shielding design must account for this. That is, the x-rays will go through a counter top and strike the lower body so shielding needs to account for this issue, as well. The danger is not just a straight line across from the source.

Finally, depending on your x-ray detector to be properly calibrated isn't a good idea. Your very life depends on the device being accurate. As such, shielding is a good idea simply for that reason - x-ray exposure can be especially dangerous for young children. You get no second chances with lethal voltages or x-rays so multiple protection methods isn't just smart, it can be a life saver.

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Enzo Carter
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Re: Creation, usage, and destruction of a cathode

Post by Enzo Carter » Sun Jan 06, 2019 2:34 pm

Richard Hull wrote:
Sun Jan 06, 2019 5:23 am
at least 6-7 feet away and use the lead shielding
Always good advice. About a year ago my dad went on a business trip to china and he was exposed to about 400cpm for 14 hrs and i was exposed to 400cpm for 4 or less minutes he was on a normal camercal flight. i will definitely be using lead shielding on my neutron runs
Bruce Meagher wrote:
Sun Jan 06, 2019 6:11 am
what happens when you run this test with plasma? Would you expect the results to be the same? If not, why would there be a difference?
Great question! but i do not know for sure? my theory is that they would be the same because an X-ray is created by an exelorated electron that collides with a material 'brimsstraholing' and the power supply (voltage and current) is giving the electrons so i think it will be the same for the same Volts and mA.

Dennis P Brown wrote:
Sun Jan 06, 2019 11:09 am
I would suggest shielding that uses slate tiles. These are extremely cheap, easy to obtain at home depot (as 18" by 18" tiles), are simple to cut to shape with an a dry abrasive saw and besides being non-toxic, are non-conductive! Win-win. Do calculate the required thickness but for under 70 kV, a half inch should suffice.
next time we go to Lowes i will be sure to look at slate tile, but for now i will use lead for X-rays and acrylic for high voltage safety. making the acrylic shield today.

as for material safety we take it seriously as the earth has provided wondrously dangerous stuff. we have, in order of danger.
Polonium 210
Beryllium
very hot uranium 238 in ore not cake
...
lead is in the list but its not mercury. we cut with tin snips and wash hands after handling. we wear gloves for most handling here, go through boxes of 50 monthly.

Bruce Meagher
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Re: Creation, usage, and destruction of a cathode

Post by Bruce Meagher » Sun Jan 06, 2019 4:56 pm

Enzo Carter wrote:
Sun Jan 06, 2019 2:34 pm
Great question! but i do not know for sure? my theory is that they would be the same because an X-ray is created by an exelorated electron that collides with a material 'brimsstraholing' and the power supply (voltage and current) is giving the electrons so i think it will be the same for the same Volts and mA.
Try a little experiment with just the mechanical pump (no turbo) and record the results for a few different voltages. Look at your notebook to see if there is something you didn't record during your previous experiment, and if the CPMs on your geiger counter are any different.

Bruce

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