High resolution soft X-ray spectroscopy and the quest for the hot (5-10 MK) plasma in solar active regions

TL;DR

This paper explores the potential of soft X-ray spectroscopy in the 100 Angstrom range to diagnose and analyze hot (5-10 MK) plasma in solar active regions, crucial for understanding solar coronal heating.

Contribution

It demonstrates that soft X-ray spectroscopy can effectively observe multiple ionization stages of Fe, enabling detailed diagnostics of hot plasma in solar active regions.

Findings

Simulated spectra show multiple Fe ionization stages can be observed simultaneously.

High count rates are achievable with proposed multilayer spectrometers.

The method provides a new way to study hot plasma in the solar corona.

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 Angstroms, as six ionisation 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.