Using of multichannel laser interferometer for vertical probing of the plasma density profile in the T-15 tokamak

Multichannel laser interferometer of vertical probing for determination of plasma density profile was installed in the T-15 tokamak. HCN-laser with HF pumping, mechanical frequency shifter, is used in the interferometer. The interferometer is noted for application of hollow dielectric waveguides and units without special frame. Results of measurements for seven chords, performed during first T-15 experiments, are presented. Phase noise, determined by vibrations, didn't exceed 20 deg. This corresponds to measurement error of average plasma density δn-bar≅2x1017 m-3 (plasma density under typical conditions will exceed 5x1019 m-3)