高真空电子管 meaning in Chinese

hard tube
hard valve
high vacuum tube

Measurements of electrical properties of electronic tubes ; methods of measurement of emission current from hot cathodes for high - vacuum electronic tubes and valves
电子管电气性能测试.第14部分:高真空电子管加热阴极
Measurements of the electrical properties of electronic tubes . part 13 : methods of measurement of emission current from hot cathodes for high - vacuum electronic tubes and valves
电子管电性能的测量.第13部分:高真空电子管热阴极发射电流的测量方法