Experiments on a nitrogen plasma created by tunnel ionization are presented. The plasma is created by a linearly polarized, 10 TW, 70 fs duration Ti:Sapphire laser focused in a nitrogen gas jet of 10 20 cm -1 neutral density. Neutral and electronic density measurements are performed by laser interferometry. Measurements of the X-ray emission in the 2 to 20 nm, realized in the propagation direction of the laser, are presented. Transitions lines of H-like, He-like and Li-like nitrogen are detected including 3d-2p and 2p-ls transitions of H-like nitrogen. Dependence of the X-ray emission with gas pressure is presented.