Quasi-Optical 34-GHz Radio Frequency (RF) Pulse Compressor

72041S03-I Accepted scaling laws predict that millimeter-wave accelerator technology can provide an increase in acceleration gradient, with a concomitant increase in final energy, for a given overall accelerator length. Compared to the Next Linear Collider (NLC) operating at 11.424 GHz with an unloaded acceleration gradient G = 77 MeV/m and two acceleration lengths L = 6 km for a center-of-mass energy of W= 0.5 TeV, a future collider operating at 34.272 GHz could be expected to have G = 200 MeV/m and W = 4 TeV with L = 12 km. This goal will require the development of a new high-power 34-GHz amplifier (a magnicon), accelerator structures, and many ancillary radio frequency (RF) components, including an RF pulse compressor for testing and operation. This project will produce the required high peak RF power pulses by developing a three-mirror, quasi-optical, running-wave resonator as a passive electromagnetic energy storage element, which, when driven with a narrow-band frequency-modulated drive signal, will discharge its stored energy as a compressed rf pulse. In Phase I, two three-mirror, quasi-optical RF pulse compressor designs will be built and tested at low power, with the aim of evolving prototypes to produce compressed pulses greater than 100 MW in Phase II. One design will be a passive compressor, which involves filling a quasi-optical resonator using narrow-band frequency-modulated drive power from the RF source, to produce 4:1 compression with efficiency of about 70%. The second design will be an active compressor, which employs plasma-filled tubes in grooves of the grating that forms one mirror of the resonator, that appears capable of achieving 7:1 to 10:1 compression with efficiency exceeding 50%. Commercial Applications and Other Benefits as described by awardee: If a future multi-TeV collider were built based on 34-GHz RF technology, demand would exist for thousands of RF circuit elements, including RF pulse compressors, leading to a possible future market of 10s of millions of dollars.