Second-Harmonic Generation in Plasmas by Nonuniform Microwave Fields

In this paper the authors give a Boltzmann-equation analysis of the nonlinear generation of the second harmonic in the current density in a slightly ionized plasma, arising because of the nonuniform nature of the applied microwave field. Under suitable approximations, the expression derived for the second-harmonic component in the current density reduces to the one derived on the basis of an elementary theory by Krenz and Kino. Some numerical results, illustrating the effect of collisions on the harmonic generation process, have also been presented.