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Schematic view of the FLASH experimental hall
The Five Beamlines
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 - 5 mm. To focus the beam, BL1 is equipped with a toroidal mirror, 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 BL1 and BL2 focus the beam down to spots of approximately 100 μm and 20 μm, respectively. At BL3 the beam can be focused down to a spot of 20 μm as well. However, this 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.
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 100 μm x 200 μm depending on wavelength and monochromator settings.
Detailed floor plan (Update Feb. 04 (.eps File))
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