First beam from the SwissFEL electron gun

The new 3 GHz photocathode gun will provide the electron bunches for SwissFEL and has recently been installed in the SwissFEL injector test facility. There, it replaced the CTF2-gun 5, borrowed from CERN. The new gun is capable now of operation with 100Hz repetition frequency and a higher field on cathode and improved field symmetry. After RF conditioning of about 4 days, the gun reached the nominal acceleration gradient of 100 MV/m at an input power of about 17 MW and pulse-width of 1 microsecond. The gun incorporates the same type of copper cathode plugs, as the CTF2-gun and accelerates the electrons in 3 cells up to a kinetic energy of 6.6 MeV. Each cell has a pick-up for amplitude and phase monitoring. The first measurements of the electron beam on the spectrometer arm confirm the expected kinetic energy. Next weeks of test injector operation will be dedicated to gun commissioning and more detailed beam quality measurements.