Stigmatic grazing-incidence x-ray spectrograph for solar coronal observations

We present the design for a stigmatic grazing incidence X-ray spectrograph designed for solar coronal observations. The spectrograph is composed of a slit, a pair of paraboloid mirrors and a plano varied-line-space grating. All reflective surfaces of the spectrograph operate at an angle of incidence of 88 degrees, and covers a wavelength range of 0.6 to 2.4nm (0.5 to 2.0keV). The design achieves 1.5pm spectral resolution and 15 μm spatial resolution over a 2.5mmlong slit. The current spectrograph design is intended for a sounding rocket experiment, and designed to fit inside a NASA sounding rocket payload behind a 1.1m focal length Wolter Type-1 telescope. This combination will have a 2.5arcsec spatial resolution and a 8 arcminute slit length. We are currently fabricating a laboratory prototype of the spectrograph to demonstrate the performance and establish the alignment procedures for a flight model.