A Wire Scanner Design for Electron Beam Profile Measurement in the Linac Coherent Light Source Undulator

The Linac Coherent Light Source (LCLS), currently under design, requires beam diagnostic instruments between the magnets in the beam undulator section. Ten wire scanners are planned as one of the primary instruments to characterize electron beam properties. The development of these wire scanners presents several design challenges due to the need for high accuracy and resolution of the wire motion (3-μm tolerance, typical) and the high intensity of the beam (1 nC, 3400-A peak, over an area of 30-μm rms radius at 120 Hz). In this paper, we present the technical specification and design criteria for the scanners. We will also present the mechanical design of the UHV-compatible drive and its engineering analysis. Lastly, we present the wire card design and discuss associated thermal and mechanical issues originating from the highly intense x-ray and electron beams.