I recently made a high frequency transformer which I will be using to drive a large spark gap tesla coil. I machined the bobbin at work from nylon and bought the 60x55x15 cores on Mouser to form a 120x55x15 core which I will expect to handle at least 1kw input and has already been tested to over 4kw input and is holding up very well with no signs of failing. I have also made taps on the primary coil (5,10,15turns) to vary output voltage and power respectively. Now I need an efficient technique to rectify this transformer.
I understand I need avalanche rated diodes. My question is, are ultra fast diodes such as a recovery time of <75ns for example automatically rated as avalanche. I do not fully understand what makes a diode avalanche so I'm struggling to find some from RS Components although I do know they are designed to break down to handle reverse voltages in a controlled fashion.
Switching frequency is 45khz on a full bridge, output voltage on the primary tap of 15turns is roughly 20kv on the secondary