Operational Performance of the Spallation Neutron Source High Voltage Converter Modulator and System Enhancements

The first-generation high-frequency switching megawatt-class high voltage converter modulators (HVCM) developed by Los Alamos national laboratory for the spallation neutron source (SNS) at Oak Ridge national laboratory have been installed and are now operational. Each unit is capable of delivering pulses up to 11 MW peak, 1 MW average power at voltages up to 140 kV to drive klystron(s) rated up to 5 MW. To date, three variations of the basic design have been installed, each optimized to deliver power to a specific klystron load configuration, for a total of fifteen (15) units installed and operational at the SNS. The units have been operated 24/7 to support successful commissioning of the SNS accelerator. Design improvements, with the primary intention of improving system reliability and availability, have been under development since the initial installation of the HVCM units. This paper will examine HVCM reliability operational data of well over 50,000 operational hours, failure modes, and modifications and improvements performed and planned to increase the overall system availability. We will focus on enhancements designed to allow for increased average power operation, as well as discuss development programs underway to provide active component protection