Effects of the electron energy distribution function on modeled x-ray spectra

Area of Science:

• Plasma Physics
• Atomic Kinetics
• Spectroscopy

Background:

• Nonlocal thermodynamic equilibrium (non-LTE) models are crucial for understanding plasma behavior.
• Electron energy distribution functions (EEDFs) significantly influence atomic kinetics.
• Non-Maxwellian and suprathermal (hot) electron populations require careful consideration.

Purpose of the Study:

• To investigate the impact of EEDFs on collisional-radiative atomic kinetics models.
• To determine the sensitivity of collisional rates to non-Maxwellian and hot electron distributions.
• To explore the development of spectroscopic diagnostics for characterizing plasmas with nonequilibrium EEDFs.

Main Methods:

• Analysis of collisional rates, including three-body recombination, under varying EEDFs.
• Comparison of rate sensitivities to EEDF functional form and characteristic energy.
• Examination of spectral line and continuum emission modifications due to hot electrons.

Main Results:

• Most collisional rates are insensitive to EEDF form and energy above threshold.
• Collisional excitation and ionization rates are highly sensitive to the hot electron fraction.
• Hot electrons alter plasma charge state distributions and spectral line intensities/features.

Conclusions:

• Robust spectroscopic diagnostics can characterize electron density, temperature, and hot electron fraction in nonequilibrium plasmas.
• Hot electron properties can be diagnosed via their influence on high-energy emission and spectral line polarization.
• Understanding EEDF effects is critical for accurate plasma modeling and diagnostics.