Pulsing a magnetron

[ElectricFireBug]

Hi-
I'm looking into the process of generating microwave pulses for and experiment and am unsure that the equipment will actually respond properly.

The goal is to produce a series of pules of ~1-4 microseconds (25% duty). I've got a CW magnetron system in mind that meets other specs for the project but the supply simply will not switch on and off quickly enough.

I guess the question is: If I supply the rapidly switching HV to a magnetron will it be able to output a similar pattern of microwaves.

Additional reference: the magnetron has a separate power supply for a filament which could be kept active while not generating microwaves. We are not planning to have peak power exceed the CW rating (although any thoughts/comments about doing that would be welcome)

Thanks

 

[BrianG]

The normal way to produce pulses in magnetrons, for radar applications at least, is to use a pulse forming network to store the required energy. Although your intended pulse width is typical to that used in many radar applications, I would say that 25% is a very high duty cycle to achieve - assuming that it does not exceed the magnetron mean power. 25% duty cycle would mainly be a problem of the recovery time of the pulse forming circuit.

Switching the HV pulse forming network can be achieved with fast turn-off SCRs (to help get the duty cycle) but note that with most magenetrons the pulse risetime shape can be critcal to ensure that the resonance mode of oscillation is correct, otherwise the output frequency and its spectrum can be erratic, which may also occur if the peak anode current is exceeded.