SwissFEL First Lasing

On Friday December 2nd at 1am SwissFEL observed for the first time FEL lasing in the undulator line. The lasing was achieved with a commission beam of low intensity, repetition rate and energy, i.e. 100pC/bunch, 1Hz and 377MeV.

The 12 undulators were set to a K value of 1.2. The resulting wavelength computed from beam energy and undulator K value is 24nm.

The FEL signal was observed with a Si-diode detector. The spontaneous radiation signal with uncompressed electron beam increased by a large factor when the beam was compressed from 10ps to about 1ps at constant charge and electron beam energy. By opening the undulator gaps a first FEL gain curve was measured.