High Heat Load Slits for the PLS Multi-Pole Wiggler

The HFMX (High Flux Macromolecular X-ray crystallography) beamline under commissioning at the Pohang Accelerator Laboratory uses beams from a multi-pole wiggler. Two horizontal and vertical slits relevant to high heat load are installed at its front-end. In order to treat high heat load with reducing beam scattering, the horizontal slit has two GlidCop blocks with 10° of turned-grazing inclination. The blocks adjust each gap of the slits by being translated, by two actuating bars, on slides fixed to a support, respectively. Water through channels machined along the actuating bars cools down the heat load of both blocks. The vertical slit has the same structure as the horizontal slit except its installation direction with respect to a vacuum chamber and its inclination angle. The installed slits show stable operation performance and no alignment for the blocks is required by virtue of a pair of blocks translating on slides. The cooling performance of the two slits has been also shown to be acceptable. In this paper, the details of the design and manufacture of the two slits are presented and its cooling performance is reported.