Parameters of metastable ArII ions in a gas-discharge plasma

The absorption coefficient and the populations of the metastable 3d(4)F, 3d(2)P, and 3d(2)G levels in a gas-discharge plasma are measured with the help of a single-frequency dye laser. The effective temperature of the distribution over the levels of the 3d(4)F(J) multiplet is shown to be close to the temperature of heavy particles in a plasma. The relaxation constants measured for different levels from the absorption saturation have close values lying in the range of Gamma(n) similar or equal to (2-6) x 10(7) s(-1). A large value of relaxation constant indicates the high rate of excitation of metastable levels. Using the 3d(4)F(7/2) level as an example, it is shown that Gamma(n) linearly depends on the electron density N-e. Electron quenching is shown to be the dominant relaxation mechanism.