Abstract
We discuss the diagnostics available to study the 5–10 MK plasma in the solar corona, which is key to understanding the heating in the cores of solar active regions. We present several simulated spectra, and show that excellent diagnostics are available in the soft X-rays, around 100 Å, as six ionization stages of Fe can simultaneously be observed, and electron densities derived, within a narrow spectral region. As this spectral range is almost unexplored, we present an analysis of available and simulated spectra, to compare the hot emission with the cooler component. We adopt recently designed multilayers to present estimates of count rates in the hot lines, with a baseline spectrometer design. Excellent count rates are found, opening up the exciting opportunity to obtain high-resolution spectroscopy of hot plasma.
Highlights
The main aim of the present paper is to present the scientific case for a soft X-ray (SXR, 90– 150 Å) spectrometer with high resolving power, high sensitivity and moderate (1′′) resolution
As active region cores have a strong emission around 3 MK, ions, such as Fe XVII, Ca XVII, Fe XVIII are mostly formed around these temperatures, rather than the temperature of peak ion abundance in equilibrium
Reva et al (2018) used CORONAS-F/SPIRIT Mg XII images to estimate an upper limit of the emission measure around 10 MK about four orders of magnitude lower than the peak value around 3 MK, which was constrained by SoHO EIT imaging
Summary
The main aim of the present paper is to present the scientific case for a soft X-ray (SXR, 90– 150 Å) spectrometer with high resolving power (capability to measure 5 km s−1 Doppler shifts), high sensitivity and moderate (1′′) resolution We believe that such an instrument would provide breakthroughs in understanding various magnetic energy conversion processes in the solar corona, in particular within: (A) non-flaring active region (AR) cores; (B) flares of all sizes. The SXR wavelengths contain many spectral lines formed over temperatures from 0.1 to 12 MK, and are suited to measure the physical state of “hot” 5–10 MK plasma, in particular mass and turbulent flows, electron densities, departures from ionization equilibrium, and chemical abundances Such SXR spectroscopic observations of this hot plasma are needed because:. Details of various observations and simulations used to assess the completeness of the atomic data, line blending and identifications are given in an extended Supplementary Material
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
