DEGENERATE 4-WAVE-MIXING IN EQUILIBRIUM ARGON ARC PLASMA

The non-intrusive degenerate four-wave mixing (DFWM) method was used t o study the local thermal equilibrium atmospheric-pressure argon are p lasma. The laser wavelength was in resonance with the 4s[3/2](0)-4p'[1 /2] Arl transition, corresponding to the 696.5 nm emission line. The A brams-Lind theory was verified and proved to be valid under the condit ions of our plasma. In the high-laser-intensity limit, the DFWM signal s were shown to be exclusively dependent on the population difference between the relevant argon states. Well resolved axial and radial prof iles of the plasma temperature and the electron density were determine d.