Study of heating effects during Thomson scattering in laser induced plasma in air

The laser induced plasma in air produced by 6 ns, 532 nm Nd:YAG pulses with 25 mJ energy was studied using the Thomson scattering method and plasma imaging techniques. Thomson scattering spectra were registered at delay times ranging from 150 ns to 1 μs after the breakdown pulses. The electron density and temperature, as determined in the core of the plasma plume, were found to decrease from 7.4×1017 cm−3 to 1.0×1017 cm−3 and from 101 000 K to 22 700 K, respectively. These electron temperatures were found to result partially from plasma heating. This effect has been observed between the beginning and the end of the probe (Thomson) pulse.