Physics of Thermal Gaseous Nebulae pp 115-152 | Cite as

# Collisionally Excited Lines and Plasma Diagnostics

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## Abstract

To this point we have discussed lines which are excited by radiative processes, mostly photoionization followed by cascade. Collisional excitation can play an Important role in many instances. If mechanical energy or magnetic energy from hydromagnetic waves are dissipated in a gas, the temperature may be raised and atomic levels excited by collisions with electrons. Collisional excitation of hydrogen, in particular, could become important. In a low-density gas which is ionized by radiation, collisional excitation of hydrogen may be less important, but that of low-lying levels of many other atoms and ions can become significant.

## Keywords

Planetary Nebula Line Ratio Plasma Diagnostics Collisional Excitation Collision Strength## Preview

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## References

- 1.Collisional Excitation and Ionization Rates for H are given, e.g., by: Johnson, L.G. 1972, Ap. J., 174, 227ADSCrossRefGoogle Scholar
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