The third flight of the Marshall Grazing Incidence X-ray Spectrometer

The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is the first X-ray slitless imaging spectrograph sounding rocket instrument designed to observe spectrally dispersed soft X-ray (SXR) images of the solar corona over a wide field-of-view. During the first flight of MaGIXS (MaGIXS-1), which occurred on 30 July 2021, several emission lines from coronal structures, including X-ray bright points, were observed. Further, MaGIXS-1 analysis also demonstrated the successful inversion of spatial-spectral overlapped data using robust unfolding algorithms. Given the demonstrated success of MaGIXS-1, the second flight of the instrument with a simplified optical design, MaGIXS-2, is scheduled for 2024 to observe high temperature diagnostic emission lines.

Results from MaGIXS-1 discovered dominant missing emission lines near 15A, arising from relatively cool plasma that peaks around 2 MK. This wavelength region hosts several closely spaced satellite lines of Fe XVII, Fe XVI and Fe XV ions, which are expected to be enhanced at lower temperatures (~ 2MK) and are currently unmodeled in the CHIANTI atomic database. This wavelength region offers one of the most unique diagnostics to measure electron temperature, as well as signatures of equilibrium state of the plasma in active regions, which has not been studied so far.

The goal of the MaGIXS-3 mission is to determine coronal heating parameters, such as the spatial and temporal properties of coronal heating events. It will make discriminating observations of key parameters, such as electron temperature, effective temperature, density, abundance, and departures from thermal equilibrium of the plasma, by observing the Sun in the SXR wavelength range. To meet this goal, the MaGIXS instrument will be upgraded with a new X-ray telescope mirror that will provide higher spatial and spectral resolution and throughput, allowing for spectral lines to be observed at the relevant spatial and temporal scales. In addition, MaGIXS-3 will also carry The Resolving Inversion Context X-ray Spectrometer (TRICXS), a high-dispersion Bragg crystal spectrometer, to spectrally resolve the lines near 14.9 to 15.9Å, which will be critical to unlocking the full diagnostic potential of this wavelength range. Here we will present the preliminary concept design of MaGIXS-3 and discuss the potential observations.