[REQUEST] 1 kV 10 A Diode and 10 kV Cable

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Joshua Guertler
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[REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Joshua Guertler » Thu Jul 04, 2019 2:57 am

Greetings,

I was looking to buy approximately 100 diodes with 1 kV and 10 A ratings to serve as a means of preventing a plasma surge from going back into my power supply (the power supply is relatively unconventional and its components require relatively strenuous current and voltage ratings). Also, I am interested in any 10 kV wire (preferably a meter's worth) with a thickness over 24 AWG.

While I was able to find offers on eBay that sold 10 of these diodes for $3.00 and some 10 kV cables, I wanted to reach out to the fusor community at large to see if there were any individuals who may be willing to sell or trade a few of these items that they might have as spares. I would much rather pay $30 to someone on this forum who will use it to move the world of fusion forward than give my money to some random person on eBay.

If you are interested in selling or trading 1-100 of these diodes or upto 2 meters of 10 kV cable (thicker than 24 AWG), please reach out to me at guertlerj21@barringtonschools.org. Thank you.

Sincerely,
Joshua Guertler

Jerry Biehler
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Jerry Biehler » Fri Jul 05, 2019 8:10 am

Why do you need 100 and why 10 amps?

Plasma surge?

A ballast resistor is really all you need if you need to limit current.

Rex Allers
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Rex Allers » Fri Jul 05, 2019 9:23 am

Yeah, I was puzzled how he arrived at the request too.

One source for HV parts that I think has OK stuff and not too unreasonable prices...
http://hvstuff.com

I think the suggested reasoning might be a reverse voltage spike? I can't think why that would happen.

As suggested by Jerry, to mute current spikes, a resistor. Or for fast changes, an inductor.
I think more thought about the perceived problem might be good. Or at least a better description of the issue you think you are addressing.
Rex Allers

Joshua Guertler
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Joshua Guertler » Fri Jul 05, 2019 1:34 pm

Greetings,

This is for a different device that I am experimenting with, not the typical transformer that would be used for a fusor. The purpose of the diodes is to prevent a reflection of the power wave, thus, protecting the power supply, as this particular power supply is known to put out rather violent waves.

Also, if anyone would know of someone who may be willing to let me rent/borrow a 10 kV DC 1000 watt power, I would be very interested to discuss options with them. Due to low-funding, i might not be able to outright buy the device, thus, a 1 week rental period may be preferable. Thank you.

Sincerely,
Joshua Guertler

Joshua Guertler
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Joshua Guertler » Fri Jul 05, 2019 1:40 pm

Greetings,

Also, I would be interested in renting out a 1 kW transformer that might be able to supply at least 20 kV if anyone would be willing to rent one out. The goal would be to use the negative lead as a source of -10 kV and at least 850 W. This would then get converted to DC by my own rectifier. Thank you again.

Sincerely,
Joshua Guertler

Michael Bretti
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Michael Bretti » Fri Jul 05, 2019 2:11 pm

Joshua,

Which diodes are you using these for specifically? In your system you have a few sets of diode stacks that perform different functions (if you are also using preionization as well). The first is to protect your charging supply, probably safe to be double your input, so only maybe 20kV, 1A is needed. You can use a couple of regular 10kV, 1A microwave oven diodes for this.

The second (in parallel with the thyratron with a shunt resistor in series) is to protect the thyratron from large voltage reversals. Should a major spike occur, the diode is actually designed to fail and short the HV supply through a high wattage, low ohm (maybe 1 ohm) resistor for safety. This probably needs to be only 20kV, 1A rated in your case.

Finally the third diode stack on the transformer secondary (if you go this route) is to prevent your DC preionization supply from shorting back through the transformer, since they are both coupled to the fusor input and the DC supply will see the secondary windings as a short to ground. This needs to be rated for at least the secondary pulse current, but really only high enough voltage rated up to your preionization supply. It would however be recommended to add an additional protection diode to the output of the preionization supply to prevent pulses from going into the supply, rated for the DC current of the supply and the max voltage of the secondary pulse output, with some overhead. These last diodes are not needed at all if you are not using a preionization supply for hot pulsing, so if you are not doing this, you should need far less than 100 diodes.

Joshua Guertler
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Joshua Guertler » Fri Jul 05, 2019 3:33 pm

Greetings Mr. Bretti,

I was considering the 1 kV 10 A diodes for the diode array, as 1 kV and 10 A turned out to be cheaper than 10 kV 1 A. this was the area where the transformer's output would meet that of the steady-state power supply.

For my design, I have recently been considering making an ion gun (rather than the steady-state power supply that would immediately be connected to the line voltage, as shown in Dr. Miley's diagram). My first run will not be with the ion gun, but I wanted to start collecting the diodes for the diode array, as these will be helpful for preventing any reflections or noise that may be caused by the ion gun once it is attached.

As for the other diodes, thank you for the recommendations.

Sincerely,
Joshua Guertler

Michael Bretti
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Michael Bretti » Fri Jul 05, 2019 3:56 pm

Joshua,

No need to worry too much about the diodes on the transformer output - running a DC ion gun to pre-ionize the background gas won't directly affect the pulse input or cause reflections directly. Also, noise from the gun won't affect pulse output going into the fusor. I wouldn't stress too much about this diode array - you can certainly implement it if you want (extra protection doesn't hurt), but may not be super critical or necessary for now. The series diode-resistor protection shunt on the primary side should help with large faults on the load side. Even on very high power modulators, an output diode on the secondary isn't used due to the absurdly high voltages and currents often seen, making it infeasible (though efforts are made to match load impedance with the driver). However, since this system is still operating at relatively low power, the only issue you may have with reflections is winding breakdown, but this won't be an issue if properly insulated.

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Richard Hull
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Re: [REQUEST] 1 kV 10 A Diode and 10 kV Cable

Post by Richard Hull » Fri Jul 05, 2019 11:35 pm

This is getting technical and this entire thread of data will be erased soon. All the advice will be lost to future reference.

No...I will not transfer the useful data to an appropriate forum.

Ask for an item...sell an item....Simple.

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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