Generation of Subgigawatt RF Pulses in Nonlinear Transmission Lines

This paper presents the experimental results on the generation of subgigawatt radio frequency (RF) pulses using two types of nonlinear transmission lines (NLTLs). In the high-voltage coaxial lines, we used the following: 1) a periodic gas gap structure and 2) uniformly loaded saturated ferrite with axial bias. The concept of the first line is based on the in-phase composition of RF fields produced by currents in the periodic gas gap structure of the inner conductor. The most stable and efficient narrow-band operation of the system with 12 cylindrical gas gaps (200 kV, 18 ns) was realized at an RF of 1 GHz and an RF power of several hundreds of megawatts. The maximum power conversion reached 10%. The second NLTL lacks spatial dispersion. The self-consistent dynamics of the traveling wave is observed by coherent magnetic switching in ferrites with axial bias. The pulsed voltage driver produced 9-ns pulses of voltage between 110 and 290 kV. With the optimum external magnetic field, the efficiency of energy conversion was similar to 10%. The peak power of oscillations produced on a resistive load was similar to 700 MW. An increase in central frequency from 600 MHz to 1.1 GHz with incident pulse amplitude was found.