Instrument Overview

The UVCS is designed to determine the primary plasma parameters that describe the solar corona from its base to as high as 12 solar radii () from sun center. This is to be accomplished by ultraviolet spectroscopic techniques.

The Ultraviolet Coronagraph Spectrometer (UVCS) consists of an occulted telescope and a high resolution spectrometer assembly (see Figure 2.1). Three spherical telescope mirrors focus co-registered images of the extended corona onto the entrance slits of the spectrometer assembly. The spectrometer assembly consists of three sections:

• The Ly- section is a toroidal grating spectrograph with an entrance slit mechanism, a neutral density filter inserter, a grating mechanism, and a windowed XDL detector (the Ly- detector). This section is optimized for line profile measurements of H I 1216 and it is also used for the Fe XII line at 1242 .

• The O VI section is a toroidal grating spectrograph with an entrance slit mechanism, a neutral density filter inserter, a grating mechanism, and an open XDL detector (the O VI detector). The O VI detector is optimized for measurements of the O VI lines at 1032 and 1037 (in first order), and is also used for the Si XII lines at 499 and 521 (in second order). The O VI section includes a mirror in the path of the Ly- beam, to focus the Ly- and Mg X 610/625 radiation from the grating onto the O VI detector.

• The white light channel (WLC) measures the polarized radiance of the K corona. It consists of an entrance aperture, a polarimeter assembly, and a photomultiplier tube. The polarimeter assembly consists of a rotatable half-wave plate, a fixed linear polarizer, a bandpass filter and a lens.

• Telescope Assembly
• Spectrometer Assembly
  • Detectors
  • On-Board Image Processing
• Sun Sensor
• Wavelength Coverage
• Flight Software