Active RF pulse compression for accelerator applications

Active RF pulse compression relies on use of a component in the RF circuit that can be switched from one state to another in a time much shorter than the desired RF pulse width. This paper reviews work wherein (a) the switching is accomplished using rapidly-ionized plasma tubes to detune a resonator that forms one reflector for an energy storage cavity, and (b) the switching is accomplished by rapidly switching the dielectric constant of low-loss ferroelectric elements in an energy storage cavity. Recent experiments to produce >50 MW compressed rf pulses at 11.4 GHz using plasma switches are described, while recent designs for ferroelectric switches are also described. The latter may have the advantage of permitting more than one switching during a single RF input pulse, thus allowing the efficiency to be greater than that for a single switching.