Simplified calculations of a thermionic converter in the ignited mode

The charged particle transport in the plasma of a thermionic converter in the ignited mode is treated to be due to the charged particle density gradient and the electric field. The corresponding coefficients as well as the numerical treatment of the ionization and recombination processes are taken from the literature, the latter one in a suitable approximation. The electron temperature is assumed to be uniform within the gap. Taking account of the boundary conditions for the electron and ion currents and for the flux of the kinetic electron energy analytical solutions are found whose numerical evaluations can easily be performed. To make allowance for the Schottky effect and a double sheath at the emitter surface is shown to be necessary and possible with moderate effort for the calculation of I-V curves. The validity limit of the model is discussed.