Bipolar high voltage multiplier project - more than 70cm hot arc discharge

[kilovolt]

Hi folks

This is my first post in this forum, so please bear with me if something doesn't quite fit the form.

I live in Switzerland, am 44 years old, married and have two children. Professionally I work as an electronics technician in a thermometry laboratory and repair measuring instruments. I have been carrying out high-voltage experiments as a hobby for almost 30 years now, but unfortunately I don't have much time left for this anymore.

Some people on youtube have asked me to present my bipolar voltage multiplier here in the forum.

The setup consists of a full bridge with two Semikron SKM200GB128D bricks, a ferrite X-ray transformer and two high multiplier towers, one for positive high voltage, one for negative high voltage. Arc ignition length is up to 75cm

Here first the electronics for the control:



The following pic shows the oscillator with bridge driver, built from a TL494, followed by a modified steve ward DRSSTC driver. Frequency is around 25kHz:



X-Ray transformer with ferrite core. It's been running in a silicon oil bath.
:


Size comparison of the X-ray transformer with an AC flyback transformer:



With the white capacitors in the picture the two cascade towers were built. They are each 1.7nF / 2.4nF with 50kV:



A first test setup of the x-ray transformer with a Jacob's ladder:



And a video of such a test:

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And here the two multiplier-towers, each consisting of 7 stages with 2.4nF and 1.7nF / 50kV caps. The brown caps at the top were replaced later with white Murata caps, same as the ones below.



The resistor chaines in the foreground of the videos (see below) are only to protect the diodes from sudden capacitor discharges. They consist of many 10kOhm / 11W and 10kOhm / 17W power resistors and they get rather warm. The setup deliversan openloop voltage of several 100kV and a short circuit current of about 35mA.

Some pics of discharges:

















A friend of mine shot a few pics with better quality:







Some videos can be found on my youtube channel:
https://www.youtube.com/user/hvpower

For example this one:

Best regards
kilovolt

[MRMILSTAR]

Very nice work and welcome to the forum!

[kilovolt]

Thank you very much for your kind words, MRMILSTAR. Do you also build a voltage multiplier?

Best regards and a happy new year
kilovolt

[MRMILSTAR]

I am currently building one with the following specs:

* 14 stages, positive output
* Each doorknob capacitor is 1.7 nF rated for 30 KV
* Each diode string consists of three 20 KV diodes rated for 30 ma
* Approximately 4 Mohms of resistance at output terminal
* Power supply is 2 AC flyback transformers in parallel powered by a ZVS driver (Royer oscillator)
* Approximate power supply voltage will be 15 KV peak
* Everything but the power supply will be in oil

Since I work slowly and methodically it will take me several months to complete the project.

[kilovolt]

Hello Steve

Nice specs for your multiplier circuit! Looks great. Please don't forget to share here your setup 

Best regards
kilovolt

[Teravolt]

that is an assume multiplier but that frrite transformer is giant. is it possible to order one  or did you find it on ebay or something. I have been looking for a long time to find one. I have a bunch of the old type of flybacks with no diodes in them that I am planning to parallel and make a full wave Cockcroft multiplier. any help would be apreciated.

[kilovolt]

Hello Teravolt

I got four of these x-ray transformers as a gift from a friend who works in the x-ray industry. But I am not allowed to sell or give them away.

By the way: I'm working on an ever bigger setup now. It is a fullwave setup with 7 stages bipolar, good for 700kV. It will be powered by two of these xray-transformers and two phases with 5kW each, in total 10kW continous power.

Best regards
kilovolt

[Teravolt]

I'm going to try building one my self if you ever wanted to sepperate with one PM me