Summary

Description

FUNCTION: Provides a facility for the assembly, test, and vacuum optical characterization of solar and coronal satellite instrumentation under ultraclean conditions. DESCRIPTION: The large SCOTCH is the primary test chamber located within a 400 ft2 Class 10 clean room. This completely dry-pumped, 550 ft3 vacuum chamber is maintained at synchrotron levels of cleanliness. Solar instrumentation up to 1 m in diameter and 5 m in length can be physically accommodated in the chamber. An instrument’s optical performance is probed and calibrated with a variety of visible and extreme-ultraviolet (XUV) sources mounted on the chamber’s 11-m beamline. The instrument is mounted on a precision pointing table equipped with motorized slides, which allows controlled adjustment of instrument pointing with subarc-second precision under evacuated conditions. The main beamline is baffled to eliminate stray reflections from the beamline walls and minimize the effect of light scattered off the instrument surfaces. A solar disk stray light rejection of 10–12 was successfully measured in the Large Angle Spectrometric Coronagraph (LASCO) C3 channel. INSTRUMENTATION: The SCOTCH is instrumented with temperature-controlled quartz crystal monitors and residual gas analyzers for real-time, quantitative measurements of volatile contamination. Various light sources can be introduced at one end of the 11-m chamber. This includes a solar spectrum simulator as well as other visible and XUV sources. The chamber contains an instrument-pointing table capable of supporting payloads with a mass of 75 kg. The precision of the pointing table is less than 1 arc second.