To produce a field reversed configuration (FRC) without using the very high voltage techniques required in a conventional theta pinch, the author has studied the steady head-on collision of counter plasma streams, flowing along the magnetic field, as ejected from two identical co-axial plasma sources mounted at each end of the apparatus. The study was motivated by the fact that such a flow can be regarded as a steady state theta pinch. Ideal Poisson and shock adiabatic flow models were used to analyse the steady colliding process. It was demonstrated that an FRC involving a large number of particles can only be produced by the weak shock mode, which is achieved when energetic plasma flow is decelerated and heated up exclusively through the Poisson adiabatic process before the streams collide.