All plastic film caps are inherently low inductance. Some better than others with very low ESR. The abbreviations for popular plastic caps are; PTFE, PU, PE, PS. They are often self-healing as well.
The self resonant frequency of the coil and cap (SRF) must be >> 300MHz to pass 1ns rise time and much higher if this is the pulse width
For Rf caps using special Ceramic under 47 pF are used but not rated for high voltage like plastic. (Murata)
I prefer Polyurethane caps from Epcos / Panasonic.
Avalanche mode sparks can also be passed with small gaps which have sufficient low breakdown gap (1kV/mm) suitable for AC, but latch under DC with sustained current.
Pls supply schematic and photo.