Thomson scattering system for measurements of radial profile of plasma density (range 0.5-5×1021 m-3) with temperature up to 2 keV was developed at the GOL-3 facility. First harmonics (=1.06 m) of Nd glass laser is used. Scattered light from different points of plasma cross-section is imaged to a set of quartz optical fibers and detected by avalanche photodiodes.

During the first 10 s after start of the relativistic electron beam injection the intense light emission from plasma is observed. Single powerful laser pulse is used for providing of good signal-noise ratio in this period. Later the plasma radiation intensity decreases and the less powerful laser oscillator operated in multiple-pulsed regime is used.

Description of the diagnostics, methodical aspects of operation, and results of the density dynamics measurements are presented in the paper.