Speaker
Description
LANSCE is a linear accelerator operating for 50+ years. Due to its age, it faces increased downtimes. The LANSCE Accelerator Modernization Project (LAMP) is underway to replace all front-end systems and improve beam delivery.
The LAMP MEBT Chopper must generate 1900 V pulses with rise and fall times under 4 ns. It must create two rapid pulses with a 1 ns pulse gap for a single beam bunch to pass through. The pulse modulator has a peak repetition frequency of 1.12 MHz and an average pulse frequency of 84 kHz.
The LANSCE effort focuses on meeting these requirements using series GaN transistors that switch synchronously. The LAMP chopper prototype features three GaN devices in series, achieving sustained switching voltages of 1000V, exceeding single FET datasheet 650V limits by 150%. A programable pulse generator produces synchronous GaN switching and shapes rise and fall times for cascaded GaN chips. Recent efforts utilizing a power-over-fiber system for low-voltage supply have reduced capacitance to ground and achieved a rise and fall time of 2.2 ns for a single board, significantly improving by several hundred picoseconds compared to a DC-DC converter with 2 pF capacitance.
Footnotes
Work was performed under the auspices of the US Department of Energy by Triad National Security, LLC, under contract 89233218CNA000001
Funding Agency
U.S. Department of Energy contract, Contract Number 89233218CNA000001
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