EBIT Measurements that Can Help Establish the Excitation Conditions in Hot Solar Upper Atmosphere Plasmas

In principle, the temperatures of solar upper atmosphere plasmas can be derived from the degree of ionization of the ions in the plasma and also from intensity ratios of properly selected lines within particular ions. When such comparisons are made, more often than not discrepancies between the two methods appear. The reason for the discrepancies may be due to wrong assumptions regarding the atomic processes that occur in the emitting plasma or to inaccuracies in the atomic cross-sections used in deriving the temperature sensitive line intensity ratios. This paper presents several types of spectral lines for which their intensity ratios are expected to be sensitive to the temperature of solar plasmas. However, before the diagnostic capabilities of these lines can be explored, the dependency of intensity ratios on temperature needs to be established from a well-understood laboratory measurement. It is proposed that attempts be made to measure some of the listed intensity ratios as a function of electron beam energy in an Electron Beam Ion Trap (EBIT) machine.