Generation of sub-GW RF pulses in nonlinear transmission lines

The paper presents the results of recent experiments on the generation of subgigawatt RF pulses using two types of nonlinear transmission lines (NLTL's). In the high-voltage coaxial lines, we used: (1) periodic gas gap structure and (2) uniformly loaded saturated ferrite with axial bias. The concept of the first element 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 a radio frequency of 1 GHz and an RF power of several hundreds of megawatt. The maximum efficiency of power conversion was 10%. The bandwidth was about 10 % at a −3 db level. The second NLTL lacked spatial dispersion and self-consistent dynamics of the traveling wave was observed in the 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 for the first eight oscillations was ∼10%. The peak power of oscillations produced on a resistive load was ∼400 MW. A linear increase in central frequency from 600 MHz to 1.1 GHz with incident pulse amplitude was found.