Long Pulse Modulators

Long pulse modulators are used to produce high-voltage, high-power pulses with durations of several hundred microseconds up to some milliseconds. The loads are one or more klystrons for producing RF power to accelerate the particle beam in superconducting cavities. After years of development and improvements in different institutes a variety of topologies  exist, and are presented. The basics of modulators, pulse requirements and klystrons are explained. Additionally, the charging of internal energy storage will be addressed. The  outlook for future developments is given.