The Design Of The Critical Current Superconducting Switch And The Study Of Its Breaking Characteristics

Pulsed power technology lays a significant foundation for high-new technology and national defense technology, which has become one of the advanced research hotspots in the world at present. Superconducting magnetic energy storage (SMES) pulsed technology derives from the combination of superconducting technology and pulsed power technology.Superconducting switch includes a variety of "switch" devices which are made by use of zero resistance, low thermal conductivity and the Meissner effect when the superconductor is in the superconducting state and also by use of the rapid change between the superconducting state and the normal state. It is one of the important components of SMES pulsed system. Only through superconducting switch, can the energy be stored without loss in a long period of time and released rapidly. The amplitude, width and stability of the output pulsed waveforms are all restricted by superconducting switch as the opening switch. SMES pulsed system requires an opening switch with low loss and short-term open circuit; whereas, the traditional opening switch is characterized by high loss and slow open velocity. Thereby, it is urgent to study superconducting switch with low loss and high open velocity. In view of this point, this thesis focuses on the study and design of an appropriate critical current superconducting switch for SMES pulsed system.This thesis starts with the analysis of the basic physical theories of high temperature superconductivity. Then it makes a necessary study on the critical current of Bi-2223/Ag high temperature superconducting tape, the effects of welding on the critical current of Bi-2223/Ag high temperature superconducting tape and the quench propagation velocity. Meanwhile, it makes a comparative analysis of the structures and characteristics of thermal-controlled superconducting switch, magnetic-controlled superconducting switch and critical current superconducting switch. On this basis, this thesis discusses the cause, feasibility and superiority of selecting the critical current superconducting switch as the opening switch in SMES pulsed systemChapter 4 and chapter 5 of this thesis make a thorough study on the design and optimization of the critical current superconducting switch. Emphasis is placed on the contrastive analysis of the superconducting switch coil, the trigger switch and the trigger source and their advantages and disadvantages are pointed out. The two chapters also complete the design and manufacture of the critical current superconducting switch and carry out the theoretical, simulation and experimental study of the turn-off characteristics of the critical current superconducting switch. Moreover, on the basis of the experimental study, the two chapters discuss the feasibility of selecting the critical current superconducting switch as the opening switch in the high-powered SMES pulsed system.According to the requirement of an opening switch characterized by low loss and short-term open circuit in SMES pulsed system and on the basis of systematic summary on the various trigger switches both at home and abroad, this thesis designs and manufactures a critical current superconducting switch. Such a new opening switch has such advantages as high repetition rate, low loss and high open velocity.