- Conference date: 15-17 November 2004
- Location: Cambridge, Massachusetts (USA)
Although collisional ionization equilibrium conditions have been much more thoroughly studied, many astrophysical situations involve timescales that are shorter than the time it would take for ionization equilibrium to have been achieved. In plasmas out of equilibrium ionization the ion fractions cannot be assumed to be a simple function of the electron temperature, but rather must be independently assessed before comparisons can be made of the relative abundances of different elements. The emission spectrum is a function of both the temperature of the surrounding electrons, kT e as well as the ionization timescale, n e t which, together with kT e determines the current charge state distribution. The accuracy of measuring an ionization timescale from the X‐ray spectrum depends strongly on our knowledge of the ionization and recombination rates as well the emission processes. However, lines that are only strong in a rapidly ionizing plasma could provide a separate proof of non‐equilibrium conditions distinct from diagnostics that are indicative of the temperature or ion fractions. In this talk I will present examples of both traditional temperature diagnostics as well as lines that would be undetectable in anything other than a rapidly ionizing plasma.
- Plasma ionization
- Plasma temperature
- Plasma diagnostics
- Astrophysical plasmas
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