A Long Pulse Modulator For Reduced Size And Cost

Abstract

A novel modulator has been designed, built and tested for the TESLA test facility.This e+ eaccelerator concept uses superconducting RF cavities and requires 2 ms of RF power at 10 pps. As the final accelerator will require several hundred modulators, a cost effective, space saving and high efficiency design IS desired. This modulator uses a modest size switched capacitor bank that droops approximately 20% during the pulse. This large droop is compcns;~ted for by the use of a resonant LC circuit. The capacitor bank is connected to the high side of a pulse transformer primary using a series CT0 switch. The resonant circuit is connected to the low side of the pulse transformer primary. The output pulse is flat to within I% for 1.9 ms during a 2.3 ms base pulse width. Measured efficiency, from breaker to klystron and including energy lost in the rise time, is approximately 85%.

Optimized resonant pulsed power supplies with deadbeat — Repetitive regulation

“…including the transformer, rectifier, filter, and equivalent DC load resistance, can be modeled as an equivalent AC resistor R AC as expressed in (1), where N T is the transformer turns ratio. For a given tank quality factor Q and resonant frequency r , the resonant inductor and capacitor can be derived as in (2) and (3), respectively.…”

“…As the most important criterion, the pulse magnitude needs to be stable and predictable so that any variation in it has a limited and acceptable influence on the acceleration. Traditional power supplies used for accelerating the particles are based upon line frequency technology that demands bulky transformers and passive components [1]. The increasingly more demanding specifications on the pulse voltage quality cannot be met by the current technology while maintaining acceptable cost and size limits.…”

A klystron-modulator RF power system for the CLIC drive-beam accelerators

“…Minimizing the stored energy in the capacitor to about 120 kJ resulted in a klystron voltage droop of ~3% over the 100Ps pulse. This droop can be compensated with a TESLA [5] style bouncer circuit.…”

Repetitive Control for High-Performance Resonant Pulsed Power Supply in Radio Frequency Applications

“…The current generation of those power supplies is based on 50/60 Hz, line frequency technology [1], [2]. A large DC-link bank is switched into the load through high voltage semiconductor devices.…”