What is a high-frequency & high-voltage capacitor?
High-frequency capacitors refer to high-voltage capacitors that can operate in high-frequency environments above 1KHZ or for long-term operation in pulse frequency environments.
There are usually two types of high-frequency capacitors: one is high-frequency capacitors, mainly high-frequency circuits represented by non-destructive testing, X-ray machines, CT machines, and the general frequency is between 20KHZ and 200KHZ. 
The other is a pulse capacitor, generally PC medium, SF medium, N4700 medium. Among them, PC medium capacitor has the longest pulse life, followed by SF, N4700 medium is relatively poor. The same 50KV2000PF capacitor, if The pulse life in the air at 30KV voltage, after aging test, the pulse life of the PC capacitor exceeds 3 million times, the pulse life of the SF is about 1 million times, and the high-voltage capacitor of N4700 medium has a life of about 50,000 times.