A Novel Soft X-ray Slitless Imaging Spectrograph for Unique Diagnostics of Hot Coronal Plasma
Amir Caspi1, Albert Y Shih2, Harry Warren3, Thomas N Woods4, James Paul Mason2, Marek Steslicki5, Szymon Gburek5, Janusz Sylwester5, Craig DeForest1, Richard Schwartz6 and Geoff Crowley7, (1)Southwest Research Institute, Boulder, CO, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)Naval Research Laboratory, Washington, DC, United States, (4)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (5)Space Research Centre, Polish Academy of Sciences, Wrocław, Poland, (6)NASA GSFC, Solar Physics Lab, Greenbelt, MD, United States, (7)ASTRA, LLC, Lafayette, CO, United States
Abstract:
Solar soft X-ray (SXR) observations from ∼0.2 to ∼3 keV (∼4–60 Å), during both solar flares and quiescent times, provide crucial diagnostics that are not available from observations at other wavelengths. Specifically, SXRs reveal plasma temperature distributions, as well as elemental abundances that probe plasma origins over a wide range of temperatures. Spectrally- and temporally-resolved measurements are essential for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are essential for understanding energy transport. The NGSPM study calls out an X-ray spectroscopic imager (T-10) as a high-priority instrument, in particular with a spectral resolution of better than 100 eV for SXR emission lines.
We describe a novel approach for a spectro-spatial imager – combining a pinhole camera with a X-ray transmission diffraction grating – that can achieve the required combination of spectral and angular resolutions at SXR energies. Such an instrument has already been demonstrated as a protoype on a sounding-rocket flight and can be proven thoroughly on a small satellite, specifically as part of the instrument complement of the proposed CubeSat Imaging X-ray Solar Spectrometer (CubIXSS) mission. CubIXSS will measure spectrally- and spatially-resolved SXRs from ~1 to 60 Å (~0.2–10 keV) with ~0.25 Å and ~25 arcsec FWHM resolutions, respectively, from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. Accordingly, CubIXSS is a pathfinder for larger satellites with improved resolution (<0.1 Å, ~few arcsec) and sensitivity, that could be integrated with focusing optics if desired. Through these groundbreaking new measurements, CubIXSS and future missions will improve our physical understanding of thermal plasma processes and impulsive energy release in the solar corona, from quiet Sun to solar flares.
