I remember Steve Ward telling about his water cooling experiences.

- Distilled water will get contaminated pretty fast, there is no real advantage over tap water.
- Tap water in a bucket, with a 230VAC pump in, has a sufficiently high enough impedance to run through the primary circuit, without any issues.
- A normal sized bucket of water will last long enough for playing some MIDI files, before being luke warm to the touch.
- You can easily change bucket, not so easy in closed loop.

My own thoughts
- You can blow compressed air through when done, to avoid corrosion, maybe add a few drops of oil.

This is the first video in a series of 3, on how to get started with the UD3.1b Tesla coil driver, FiberNet and TeslaTerm.

I love you all for the great work!

Temperature rise at 11 degree Celsius is border line to problems in longer runs without good forced air cooling.

I would place SKM100s around 400-600A depending on resonant frequency, do the loss calculations! https://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/igbts/ or scroll down to table of proved IGBT speeds/current.

It might look good on paper, but if you do not consider your driving parameters and do the calculations, its only guesswork

Calculate power dissipation to find out how hard you can drive it, I show how to do that here: https://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/igbts/

Rough estimates would be to look at DRSSTC Tesla coils from Pythagoras, a^2 + b^2 = c^2, lets a and b be the same length/height as Tesla coil and maximum spark length is c. This seems to fit from table top coils to Lightning on demands 40 feet (13 meters) huge one https://www.youtube.com/watch?v=B7zuuoYJFmg .

Costs does however seem to rise squared to the size, so while costs are ^2, gain is only sqrt(2).

The Barnkob Pythagoras Tesla Coil Theorem



 You want long sparks? How deep are your pockets?

I visited the Danish Electricity Museum back in Autumn 2023 and by pure coincidence it was their last opened weekend of the year and they would pack down to close for good, due to lack of funding.

Finn Hammer from www.hammertone.com built their Tesla coil back in 2003. I got to film its last ever public show, as an re-opening of the museum, might not be what it was originally when it closed.

It sounds like you are searching for the term "Larger Than Resonant" or LTR, when designing a MMC for a SGTC that does NOT resonate with the impedance of your NST, as this will destroy your NST. So try to look into that term and there should be plenty of information to find on google searches.

It is called a tuned circuit, a resonant LC circuit or a tank circuit, many different names for the properties of pumping energy into a self-oscillating LC circuit.

You do need something to transfer that energy to, so a secondary tuned circuit, with a different LC ratio needs to be added. This is how a DRSSTC Tesla coil works.

A induction heater / stove / cooker works without a secondary LC circuit, that is purely a pan load (which represents some complex load) that gets the energy transferred.

Resonant circuits can ring up to very high currents, as you discovered, so you can transfer a lot of energy with short on-times.

I found a old and discarded smoke cannon at a scrap yard! It looked in rough shape, but still had some oil in its container. With a bit experimentation and at last forcefully feeding it oil, it gave off its smoke!

As a bonus, I got most of my workshop lubricated from half-burned oil smoke raining down droplets everywhere!

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Flyback transformers are special in having an air gapped core, which is utilized by the driving method Flyback converter topology.

So a flyback transformer is just a air gapped transformer. It is the driving method where energy is stored in the core in the first half cycle, switch turns off and energy is transferred to the secondary winding in the second half cycle.

The term flyback comes from Cathode ray tubes (old TVs and monitors) where the abrubt saw tooth like output, got the beam in the cannon to flyback to draw the next line on the monitor.

In high voltage world, we abuse the shit out of them with all other kinds of drive modes than flyback We feed them with ZVS, single switch, half-bridge or full-bridge inverters to get the highest possible voltage output, often leading to a premature death of the transformer.

To drive it continuesly, the air gap should be removed, as the half cycle energy storage is no longer being used. On the other side, core saturation will happen much faster.