Frequency up-conversion and spectral breaking of a high power microwave pulse propagating in a self-generated plasma

Summary form only given. A frequency up-conversion process may held to avoid the cutoff reflection of a powerful electromagnetic pulse propagating in a self-generated plasma. Both chamber experiments and numerical simulation have been performed. When the field amplitude only slightly exceeds the breakdown threshold field of the background gas, the carrier frequency (/spl omega/) of the pulse shifts upward during the growth of local plasma frequency (/spl omegasub pe/). Thus, the self-generated plasma remains underdense to the pulse/sup 2/. However, the spectrum of the pulse starts to break up into two major peaks when the amplitude of the pulse is further increased. The frequency of one of the peaks is lower than the original carrier frequency, and that of the other peak is higher than the original carrier frequency. The frequency downshift result is believed to be caused by damping mechanisms.