Fast X-Band Phase Shifter

72922-In order to achieve the high peak power required to drive a future electron-positron collider, an approach known as DLDS (delay line distribution system) combines the output powers of eight 75-MW X-band klystrons, and directs one-quarter-width slices out of the 600 MW, 1.6 microsecond pulse to four successive accelerator sections using phase interference due to rapid klystron phase shifts. A much simpler alternative, known as active DLDS, would use a fast active switch to divert the one-quarter-width slices from the high-power pulse, without need for the klystron phase shifts. This project willl develop a fast phase shifter that could be used as the active element in such a fast switch for active DLDS. Using advanced ferroelectric material and structures already developed, Phase I simulations showed that low loss and reasonable electrical tunability can be achieved in a phase shifter capable of causing the switching of 500 MW peak power X-band pulses. Advanced ferroelectric samples were prepared that showed an acceptable range of electrical permittivity, loss tangent, and electrical tunability. Ring-shaped samples, similar in size to what is required for the phase shifter, were fabricated. A preliminary design for the high-power device to be fabricated and tested in Phase II was devised, based on use of existing ferroelectric materials. In Phase II, an engineering design for the phase shifter will be completed. Ferroelectric rings with required dimensions and electrical properties will be fabricated for integration into the phase shifter structure. High-power tests, to a peak power level of at least 50 MW, will be carried out in X-band test facilities at the Naval Research Laboratory. Commercial Applications and Other Benefits as described by awardee: A fast switch for high-power microwaves should have many uses beyond that identified for powering accelerator sections for a future electron-positron collider. These uses include phase array radar for military and civilian use, and active control of industrial processes that involve high-power microwaves