ONE-DIMENSIONAL THEORY OF A THERMAL-EQUILIBRIUM MHD CHANNEL

The processes and variation of parameters inside an equilibrium MHD ch annel used as a generator or propulsion device are presented and exami ned. The performance and internal processes can be described by a set of equations comprising a two-level particle model for the seeding sub stance, coupled with the transport equations for the carrier gas. The one-dimensional model assumes uniform properties over the channel cros s-sectional area and allows for variations of velocity, pressure, temp erature, density, electric field, current density and electrical condu ctivity in the direction of the flow. The plasma composition is determ ined by particle balance equations which include collisional, radiativ e, diffusion and flow processes. This comprehensive model should aid a nd result in an accurate description of the processes inside a MHD cha nnel and allow for a better interpretation of experimental results. An example of a linear constant Mach number segmented electrode generato r operating in the Faraday mode with a helium, seeded with a few perce nt caesium, gaseous mixture is presented in this study. The calculatio ns for typical MHD generator values of pressure, temperature, velocity , magnetic field, seed fraction and electrical efficiency show large d eviations on predicted performance between the particle balance and Sa ha-Boltzmann models. The generator performance is also sensitive to th e seed radiation and convection processes.