The Five Beamlines (FLASH1)

Schematic view of the FLASH experimental hall

Schematic view of the FLASH experimental hall

The experimental stations at the beamlines BL1, BL2 and BL3 utilize the direct FEL pulses. When entering the experimental hall, the FEL beam has a width of about 3 - 10 mm depending on the wavelength. To focus the beam, BL1 is equipped with KB mirrors, while ellipsoidal mirrors are used at BL2 and BL3.

Most users need highly focused and extremely bright FEL pulses, e.g. for experiments in plasma physics, cluster science, and materials research. The mirrors at BL2 and BL3 focus the beam down to spots of 20 μm. The beam can also be used unfocused for experiments that do not require a high photon density, or by research groups who prefer to install their own focusing optics. In the latter case a spot size in the range of 1 - 2 μm is reachable with back­-reflecting multilayer mirrors.
At BL1 the beam can be focused down to a spot of few μm into to the permanent endstation CAMP.

The FLASH photon pulses have an inherent bandwidth of approximately 1 percent, but for many experiments monochromatic radiation is needed, e.g. to study excitation processes in molecules or atoms, and in some pump-and-probe experiments. Thus, a high-resolution plane grating monochromator has been developed to serve the beamlines PG1 and PG2 with FEL pulses of narrower bandwidth.

When the FEL beam hits the grating, a selected wavelength passes through and proceeds to one of these beamlines, while optionally the zeroth order including the higher harmonics is deflected to a special diagnostic port. The monochromator is tunable; by moving the grating and the plane mirror by remote control, different wavelengths can be picked out of the approximately 1-percent FEL bandwidth. An energy range from 20 eV to 1000 eV is covered. The spot size at PG2 is presently about 50 μm x 100 μm depending on wavelength and monochromator settings.

  Details on the individual beamlines are found here.