Effect of Metastable States on the Emission Lines of OIII, OIV and OV Ions

Oxygen ions such as OIII, OIV, OV and OVII have metastable states, for example 2s2p 3 ( 5 S), 2s2p 2 ( 4 P), 2s2p( 3 P) and 1s2p( 3 P). When the electron density is high ( n e >10 10 cm -3 ), the population densities of metastable states also become high, and the intensities of emission lines and the populations of ionization states are affected by the collisions with electrons. We have studied the density dependence of the line emissions and ionization balance including the populated metastable states. We apply these results to the diagnostics of plasmas.