Electron density diagnostics for various plasma structures of the solar corona based on Fe XI-FeXIII lines in the range 176 207 Å measured in the SPIRIT/CORONAS-F experiment

The relative intensities of FeXI-Fe XIII lines in the range 176 207 Å have been measured for various plasma structures of the solar corona using data from the XUV spectroheliograph of the SPIRIT instrumentation onboard the CORONAS-F satellite with an improved spectral sensitivity calibration. Electron density diagnostics of a plasma with temperatures 0.8 2.5 MK has been carried out in active regions, quiet-Sun and off-limb areas, and, for the first time, in extremely intense solar flares. The density range is (1.6 8) × 10⁹ cm^-3 for flares, (0.6 1.6) × 10⁹ cm^-3 for active regions, and ∼5 × 10⁸ cm^-3 for quiet-Sun areas. The calibration accuracy of the spectral sensitivity for the spectroheliograph has been analyzed based on spectral lines with density-independent intensity ratios.