Data provide two-dimensional distribution of the effective thermal conductivity λ+λ_T in the central plane (X-Z) of the jet plume operating in pure Ar with a flow rate of 40 NLPM. Electric current in the torch is 600 A. The first column contains the axial position z in units of mm, the second one contains the radial position in units of mm, and the third one gives the effective thermal conductivity λ+λ_T in units of W/m/K.