thermal cathode

例句：

1. 1. Thermionic valves are used in a variety of electronic devices.
   热阴极二极管用于各种电子设备中。
2. 2.Thermionic valves are widely used in power generation and heating systems.
   热阴极二极管在发电和供暖系统中广泛应用。
3. 3.Thermionic valves have a high efficiency and low power consumption.
   热阴极二极管效率高，功耗低。