Electron density diagnostics from Fe ix and Fe x. Intensity ratios of two lines are shown. The intensity units are phot cm^-2 s^-1 sr^-1. Black lines correspond to the Maxwellian distribution, green to κ = 5, and red to κ = 2. Individual line styles are used to denote the T-dependence of the density diagnostics. Blue lines denote the same ratio according to the atomic data from CHIANTI v7.1.