TVs is a pulse power switching device with strong development potential in recent years. TVs is characterized by using vacuum as the insulation and arc extinguishing medium between main contacts, and using specially designed trigger pole to control the switch for rapid closing. It has the advantages of high load capacity, wide working voltage range, rapid dielectric recovery, compact structure, convenient use and simple maintenance. It can be used as overcurrent and overvoltage protection devices, as well as high-power and high-voltage rectifier and converter.
A series of advantages of TVs make it widely used in many fields, such as fault current limiter of power system, electromagnetic railgun launch in new electrical technology, pulse plasma engine, electrothermal chemical gun and high repetition rate pulse power supply.
The basic structure and sample object of TVs are mainly composed of an insulating shell, a metal shield, a pair of main electrodes and a trigger electrode. The insulating shell is made of ceramic (solid and small) or glass (simple process and low cost), and the air pressure in the pipe is maintained at 1 × 10-4 PA or less. The insulating shell plays the role of support and insulation while ensuring the vacuum degree in the pipe; The metal shield can prevent the metal vapor generated by the arc from depositing on the inner surface of the shell, resulting in the decrease of the flashover strength on the inner surface of the shell. On the other hand, it can also adjust the electric field distribution in the switch tube.
The trigger electrode is responsible for the important trigger task, providing the initial plasma for the switch, so the structure design of the trigger electrode directly affects the performance of the switch; The main electrode conducts a large current when the switch is working, which makes the main gap conductive. Therefore, its structural design and the selection of anti ablation electrode materials have an important impact on the conduction characteristics of the switch.
