Electron swarm coefficients for H$_{2}$O and H$_{2}$O-N$_{2}$

We have used a pulsed Townsend technique to measure the electron drift velocity v$_{e}$, the density normalized longitudinal diffusion coefficient ND$_{L}$, and effective ionization coefficient ($\alpha -\eta )$/N, in water vapour and water vapour-nitrogen mixtures over the density-reduced electric field range E/N, 16-650 x 10$^{-17}$V cm$^{2}$. The v$_{e}$ values are in good agreement with previous ones, while those for ND$_{L}$ agree well with a previous calculation. The limiting value for E/N was found to be E/N$_{lim}$=137 x 10$^{-17}$ V cm$^{2}$. For E/N$<$70x10$^{-17}$ V cm$^{2}$, the v$_{e}$ curves lie below that for pure N$_{2}$; however, the 10{\%} H$_{2}$O-N$_{2}$ curve for v$_{e}$ shows the trend for negative differential conductivity. The ($\alpha -\eta )$/N curve for H$_{2}$O shows a shallow, negative minimum, in disagreement with a recent measurement using the steady-state Townsend technique. The H$_{2}$O-N$_{2}$ curves for ($\alpha -\eta )$/N show a progressively smaller minima, together with a trend to lower values of ($\alpha -\eta )$/N as the N$_{2}$ content in the mixture increases. This research aims to provide a complete set of self-consistent electron swarm parameters for the simulation of flue-gas discharges.