7kV pulses, not recommended for CW use. You typically run those at a 1% or less duty cycle, discharging a pulse from either a length of coax cable ( for a better rise and fall time) or a capacitor, using something like a thyratron, ignitron or other pulse capable vacuum tube ( low power you can use regular transmitter valves by grossly overrunning them just short of space charge limiting and cathode emission and relying on the low avewrage power to handle the heat) and use another vacuum tube ( with a heater winding isolated to 7kV) to limit the charging current into the pulse network.
You can get pulse outputs that are in the MW range, though the average power will be very low, using simple circuits. You might be able to run it using regular silicon devices, though you probably will have to make a cascode of 10 1kV power devices ( and some scary drive to turn them all on and off simultaneously) to do the pulse drive. At least charging the pulse network can be easy using a SMPS to generate the charge voltage and use HV rectifier diodes to get DC, just turn off the charge circuit before firing.