Electron heating in the measurement of electron temperature by Thomson scattering: Are thermal plasmas thermal?

Thomson scattering measurements have yielded electron temperatures T-e up to 7000 K greater than the ion temperature in 1 bar thermal plasmas. To account for laser heating of electrons, T-e was measured as a function of laser pulse energy, and an unperturbed T-e obtained by linear extrapolation to zero pulse energy. It is shown that the absorption of laser energy by the electrons, and the cooling of the electrons by collisions and radiative emission, depend strongly on T-e. Considering all these processes gives T-e values that are in much closer agreement with the ion temperature.