Commissioning of the X-band Transverse Deflector for Femtosecond Electron/X-Ray pulse Length Measurements at LCLS

X-ray free-electron lasers provide ultrashort x-ray pulsesfrom several to a few hundred femtoseconds for multidisciplinaryusers. However, tremendous challenges remain inthe measurement and control of these ultrashort pulses withfemtosecond precision, for both the electron bunch and thex-ray pulse. A new diagnostic scheme adding a transverseradio-frequency deflector at the end of the linac coherentlight source (LCLS) undulator beamline has been proposedearlier. Two 1-m long deflecting structures have been installedat LCLS during the summer of 2012. Installationof the high power RF components including the klystron,waveguide, RF controls etc. has finished and commissioninghas started since the spring of 2013. We report the latestprogress of the commissioning of the deflector at LCLS