We demonstrate a new 11.424 GHz SLED-type rf pulse compressor for powering high-gradient x-band photoinjectors with pulse lengths around 20 ns. rf pulse compression provides a practical path to higher peak power at the cost of pulse length for various applications such as rf deflectors for electron beam diagnostics on free-electron lasers. Our new compact pulse compressor uses spherical cavities supporting axially symmetric TE modes which have minimal electric fields on the cavity surfaces, intended to improve high-power robustness as compared to existing compact spherical SLEDs which use a TE dipole mode. We present the design of this pulse compressor composed of two spherical cavities and a waveguide hybrid. The two cavities and hybrid have ${\mathrm{TE}}_{01}$ circular waveguide ports. This pulse compressor was built and high power tested at SLAC. These tests demonstrated a peak power of 317 MW by compressing 52 MW, $1\mathrm{\mu }\mathrm{s}$ pulses generated by a SLAC XL-4 klystron representing, to our knowledge, the highest peak power achieved from a single-stage compact SLED rf pulse compressor at x-band. The full width at half maximum of this compressed pulse was $(27.1\pm 1.1)\mathrm{ns}$. We conjecture that this development demonstrates a viable route to reaching the high-gradient, short pulse regime for accelerating structures and rf photoinjectors.

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• Beam diagnostics
• Room temperature RF
• Free-electron lasers