Experimental study on the performances of second-harmonic dispersion interferometers at 10.6 µm and 1064 nm for plasma density measurements.

Two common-path interferometers based on and : (Nd:YAG) lasers are benchmarked with a two-arm microwave interferometer on a hydrogen plasma produced by an RF discharge and injected into a large magnetic-confinement vessel. The ∼10 line-integrated electron density is clearly measured in agreement by the interferometers. The frequency spectrum of the measured data is analyzed on the 20 kHz range for all interferometers and up to 600 kHz for the Nd:YAG laser-based interferometer.