Vacuum double crystal x‐ray monochromator for synchrotron and related uses

摘要

A full featured, versatile double crystal x‐ray monochromator using the Golovchenko–Levesque–Cowan1 scheme has been developed to operate in near UHV conditions. The vacuum requirements arise from the use of the monochromator at low x‐ray energies in synchrotron beamline applications. The feedback stabilized instrument can scan Bragg angles from 6° to 68° [2.13 to 16.3 keV using Si(111) crystals]; the scan can be effected without losing lock. The instrument’s features include an incremental encoder with absolute indexing, four stepping motor driven alignment adjustments, cooled crystal holders, and a piezo pusher, all operating in vacuum. The complete instrument achieves 6×10-8 Torr after a mild 100 °C bakeout. This vacuum x‐ray monochromator will be useful in other areas such as plasma diagnostics and x‐ray laser studies. The in‐vacuum stepper motors developed for the monochromator can solve a wide variety of motion in vacuum problems; the effects of operating parameters on mechanical and vacuum performance have been investigated and guidelines for sensible driving electronics have been developed. Optical test data taken with the monochromator will be presented.