Kinetics of collisional-radiation recombination and ionization in low-temperature plasma

A review is made of the approaches and approximations used by different authors to calculate coefficients of collisional-radiative ionization (β) and recombination (α). In calculating these quantities, consideration is given to a wide range of varying conditions in plasmas, and account is taken of different factors violating thermodynamic equilibrium, such as a possible departure from a Maxwellian distribution of free electrons, radiation escape with allowance for reabsorption, etc. Simple analytical expressions are given for β and α, as well as calculation results for plasmas of different compositions and different parameters. Experimental studies are also discussed in which β and α are measured. Calculation and experiment are compared and found in fair agreement. Special attention is given to major factors of nonequilibrium, affecting the rate of electron density change in different experimental conditions.