Short Pulse, Multistage Generator for 200MW RF Sources

Future linear collider applications in high energy physics require higher frequency and higher-power radio frequency (RF) sources. One application for testing accelerating structures and components requires 150 to 200MW at 30GHz with 130nsec pulse length. For the power modulators needed to drive the RF sources, the power requirement is greater than 450kV, with high-current square-pulse shape. Typically, power modulators are limited in rise time; therefore, pulse lengths of 1 µsec are used, followed by RF compression. In order to improve efficiency and reduce overall system complexity and cost, this project will develop a power modulator with a faster rise time and shorter pulses. The modulator is based on the previously-developed Tunable Multistage Blumlein concept. This concept has shown a capability for producing pulses with rise times less than 30 nsec, which allows square pulses to be produced with high efficiency. By applying this concept to an RF source greater than 100 MW, the need for RF pulse compression would be greatly reduced or eliminated. In fact, the direct production of a 200 MW RF pulse at 130 nsec and 100 Hz would become a distinct possibility. In Phase I, a Tunable Multistage Blumlein generator will be manufactured and tested at a power level greater than100 kV. Voltage flat-top variation will be measured. Based on these results, a design for Phase II at 500kV will be developed. Commercial Applications And Other Benefits as described by the Applicant: The technology should make new RF power sources available for testing the components of future accelerators. Similar modulators may be utilized in fusion energy research and defense applications. Commercial applications include food processing and radar.