Robust High Average Power Modulator

The modulators for the Spallation Neutron Source at Oak Ridge National Laboratory are the highest-average-power modulators in the world. These modulators are not yet reliable, despite ten years of development. There are failures in the switching transistors of the high-power inverters and in the resonant capacitors across these transistors. There is also a limitation fundamental to the design: the inverters switch the full current 30 times during each pulse, which is done to compensate for the droop. These full-current pulses dissipate substantial power in the transistors, raising their temperature and limiting their reliability. We will design a modulator with a single switch array. This is not vulnerable to inverter failures, nor does it have the resonant capacitors that can fail. Finally, the switch closes and opens only once per pulse, which means lower temperatures in the transistors, and correspondingly higher reliability. DTI