Non-thermal and non-equilibrium effects in soft X-ray flare spectra

Processes leading to the excitation of soft X-ray line spectra are discussed in relation to their thermal or non-thermal nature. Through analysis of calcium spectra from the XRP experiment on SMM, it is shown that the ionization balance during the gradual phase of flares is effectively in the steady-state. A search of suitable complex flares with multiple impulsive features has shown indications of soft X-ray line intensity anomalies, consistent with the presence of a non-thermal electron component.