  We present experimental measurements of a pulsed plasma gun, using two-colour
imaging laser interferometry and spatially resolved Thomson scattering.
Interferometry measurements give an electron density
$n_e\approx2.7\times10^{17}$ cm$^{-3}$ at the centre of the plasma plume, at 5
mm from the plasma gun nozzle. The Thomson scattered light is collected from
two probing angles allowed us to simultaneously measure the collective and
non-collective spectrum of the electron feature from the same spatial
locations. The inferred electron densities from the location of the electron
plasma waves is in agreement with interferometry. The electron temperatures
inferred from the two spectra are not consistent, with $T_e\approx 10$ eV for
non-collective scattering and $T_e\approx 30$ eV for collective scattering. We
discuss various broadening mechanisms such as finite aperture effects, density
gradients within the collective volume and collisional broadening to account
for some of this discrepancy. We also note the significant red/blue asymmetry
of the electron plasma waves in the collective scattering spectra, which could
relate to kinetic effects distorting the distribution function of the
electrons.
