Research On HTS Loss-free Pulsed Power Delay Network

Since the pioneering work of Matin's research group in 1960s, the high pulsed power technology has always been attached great importance by the defense departments of many countries in the world. It has begun to emerge in civilian areas in the recent years. In the many applications of high-power pulses, some loads require higher power than the source is able to supply. To meet this demand, it is usually required to delay those high-power pulses for relatively short intervals. For the high power pulses with long time delay, the conventional delay line is always difficult to meet the requirements due to large attenuation, bad front-edge, high power-loss, large bulk and so on. The zero-resistance property and high current carrying density of superconductors can reduce signal attenuation, distortion, weight and bulk potentially. The work on high power delay lines or delay network made by high-temperature superconducting (HTS) materials has not been reported at present. Therefore, this thesis makes some original researches on HTS loss-free delay network mostly by the means of experiments, and then focuses on the engineering applications.Firstly, this paper discusses the basic characteristics of delay network according to the elementary transmission line theory. Then, a rapid new method is proposed to solve the equations set of delay network and the first-order linear ordinary differential equations which are similar to it, and a concise result is obtained, which is similar to that of a simple first-order circuit. The simulation studies are done by the programming code based on this new method.Secondly, a small HTS delay network experimental platform is designed in the paper. Based on the platform, the following experiments are done: voltage pulse experiments, current pulse experiments, vary pulse width experiments and matching experiments.The corresponding conclusions are obtained: (1) Under the matched resistive load, compared with a normal conducting lossy delay network, the HTS loss-free delay network can reduce the amplitude attenuation of voltage pulses, the front-edge distortion of current pulses and improve the power transmission efficiency significantly; and (2) In order to reduce the distortion of the original signal, its main frequency components should be less than the cut-off frequency of network as much as possible, and the network should match with load.Finally, some problems related to engineering applications are studied in this paper. The formula to estimate the parameters of networks is educed and a simulation example is demonstrated. The realization of HTS inductors is also discussed, including the facture ofμH-class inductors and the performance of 2G HTS tapes. At last, the layout of inductors is been studied, and the programming code is written to calculate the spatial distribution and contour map of the coupling coefficient of two parallel superconducting cakes, which is verified by experiments. It is very useful for the layout of inductors with low coupling coefficient in the engineering applications.