Saturday 27 September 2014

Thyratron Tesla Coil Plans, Theory and Schematics

I achieved success with my Thyratron Tesla Coil getting 10cm streamers before pulse capacitor failure.

Below is the schematic:

Benefits of a parallel LC network:
  1. Reduced load on the thyratron
  2. No need for precise timing
  3. Significant reduction in reverse voltage
  4. Smaller duty cycle on thyratron
  5. Pulse repetition frequency adjustable without effecting tuning

Detrimental effects:
  1. Parallel LC network acts as a short circuit
  2. Increased stress on tank and pulse caps
  3. Less control over the tank circuit
As the thyratron is only dumping energy into the LC network the load across it is reduced. If it were used as a spark gap with reverse voltage bypass the thyratron would have to pass each oscillation between the capacitor and inductor. This could increase thyratron load by a factor of 10 and also risk damage to the cathode and anode if the reverse voltage failed.

One would need to also provide micro second timing to ensure the thyratron fired at the right time to ensure high efficiency and would require complicated and expensive circuitry. This level of difficulty is outside of my range of expertise and it is also highly impractical. Why expose a unipolar switch to bipolar currents?

A parallel LC network is the simplest and easiest way to use a thyratron in a Tesla Coil and it uses the thyratron how it was developed. Namely to switch high voltage DC at high currents over a very short time and then have a very long relaxation period, whilst not being exposed to transients and reverse voltages.

Here is a video of it in operation:




Here are some theory videos I made:
 

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