  A method for evaluating the radial temperature profile of a plasma channel is
presented. The radiation spectrum of mixture of Hydrogen Nitrogen plasma in
capillary discharge is collected. Assuming a local thermal equilibrium, the
temperature is derived from the ratio of two emission lines (N +,N 2+). The
method presented here does not rely on Stark broadening of the emitted H-alpha
line hence can be utilized in a wide range of plasma constituents and
densities, leading to an improved control of the plasma channel parameters as
required by future laser wakefield acceleration schemes.
