WTB High Voltage Capacitor

[Anthony P]

I am revisiting the Scientic American Flash-lamp Pumped Dye Laser, and am searching for a suitable capacitor. In the past, Condenser Products has custom made anything I could imagine. They can not help this time, nor can e-bay et.al. This is what I am looking for:

20KV or more
As close to 1microfarad as possible
MUST be low inductance type, fast discharge

At this point I am considering a homemade cap. My N2 project rquired the construction of a 12"x18"x.010" copper sheet cap. It clocks in at 10nF. 100 layers should do the trick. I would much rather just fork out the dough to buy buy one, but I can't find one. A home-made 100 layer cap is a little nuts, but it would not be a real laser project if there wasn't some degree of insanity involved.

 

[paul1598419]

If you must build your own capacitor, look into dielectrics. They can increase your capacitance without increasing plate size. 1 uF at 20 kV is a bit unusual.

 

[Alaskan]

I have used oil filled capacitors in series to increase the voltage, of course the capacitance is reduced that way, but find high enough ones and 20 KV should not be too difficult to reach and still have one microfarad. You may want balancing resistors between them though.

Edit: Two of these, if you can find them will give 1 uF at 20 KV:

2uf 10KV High Voltage DC Oil Capacitor AOC 10M2ES | eBay

2uf 10KV DC Oil Capacitor 10M2ES. Excellent USA made DC capacitor.

www.ebay.com

This same seller has a 1 uF 10 KV oil filled capacitor listed too, but since he has only one, I don't think you would want to use it as the capacitance would only be .666 uF when in series with 2 uF. If he had two, you could series parallel those two with the larger one and get your 2 uF.

You could buy that one 2 uF and then these five capacitors to series together with it, since they are 35 uF each, maybe achieve what you want:

35uf / 2000V. Capacitor; Energy Storage (No PCBs), Sprague 30P171 | eBay

35uf / 2000V. Capacitor; Energy Storage (No PCBs), Sprague 30P171. Condition is Used. Capacitors have been in flawless service for years without any degradation or failure.

www.ebay.com

You probably already know this formula well, but just in case: Capacitors connected in series will have a lower total capacitance than any single one in the circuit. If you have not seen it, click to see the formula.

 

[Anthony P]

Alaskan: Thank you so much for your help. I will look up the inductance on those caps to see if they are suitable. BTW, like the new avatar.

Paul: I am going to do some bench tests on mylar sheets this weekend. It has a very high dielectric strength and is readily available in a variety of thicknesses. It apparently has some use in quilting and other art stuff.