This is the pic of a small form factor Indian Marx generator , Marx generator purpose is to generate a high voltage pulse from a low voltage supply in order to power HPM high power microwave systems. Marx generator are of various sizes depending on the output required .
Courtesy : DFI PK.
Small sized Marx generators are required for EMP bombs in order to generate the desired high voltage output in a small form factor necessary to produce electromagnetic pulses via suitable pulse generating technologies. Also there are other technologies which can be used in place of the above.