含稀土氧化物难熔盐浸渍W基直热式阴极研究

为了提高磁控管阴极的工作性能, 采用新型La₂O₃/Y₂O₃-Gd₂O₃-ZrO₂难熔盐浸渍W基制备直热式阴极, 并对该阴极的热发射特性和寿命特性等进行了测试。热发射测试结果表明, La₂O₃-Gd₂O₃-ZrO₂浸渍阴极在1600℃可提供超过0.18 A/cm²的空间电荷限制区电流密度。在同等发射电流下, 该浸渍阴极的工作温度比纯W阴极降低至少300℃, 该阴极在1750℃, 0.5 A/cm²直流负载下, 可以连续工作2100 h。当以Y₂O₃代替La₂O₃, 采用相同的配比制备阴极时, 1400℃、1700℃下即可分别提供超过0.6、3.4 A/cm²的空间电荷限制区电流密度。Y₂O₃-Gd₂O₃-ZrO₂浸渍阴极的工作温度比La₂O₃-Gd₂O₃-ZrO₂浸渍阴极降低至少400℃, 该阴极在1600℃, 1.5 A/cm²直流负载下, 可以连续工作2600 h。最后, 对这两种新型含稀土氧化物难熔盐浸渍阴极的热发射机理进行了探讨。

Rare Earth Oxide Refractory Metal Salt Impregnated W Based Directly-Heated Cathode

Cathode plays an important role in the magnetron. In order to enhance the emission current, reduce the operation temperature and prolong the lifetime of the pure W cathode applied in the magnetron, a new La₂O₃/Y₂O₃-Gd₂O₃-ZrO₂ impregnated W based directly-heated cathode was developed. The thermionic emission properties of the La₂O₃/Y₂O₃-Gd₂O₃-ZrO₂ impregnated cathode were measured. The results show that the La₂O₃-Gd₂O₃-ZrO₂ impregnated cathode can provide more than 0.18 A /cm² current density for the space charge limitation (SCL) at 1600℃. Under the same thermionic emission level, the working temperature of the La₂O₃-Gd₂O₃-ZrO₂ impregnated cathode is at least 300℃ lower than that of the pure W cathode. Lifetime of the La₂O₃-Gd₂O₃-ZrO₂ impregnated cathode reaches 2100 h at 1750℃ with dc load of 0.5 A/cm². The Y₂O₃-Gd₂O₃-ZrO₂ impregnated cathode can provide more than 0.6 and 3.4 A /cm² current density for SCL at 1400℃, 1700℃, respectively. Under the same thermionic emission level, the working temperature of the Y₂O₃-Gd₂O₃-ZrO₂ impregnated cathode is at least 400℃, lower than that of the La₂O₃-Gd₂O₃-ZrO₂ impregnated cathode. Lifetime of the Y₂O₃-Gd₂O₃-ZrO₂ impregnated cathode reaches 2600 h at 1600℃ with dc load of 1.5 A/cm². At last, the thermionic emission mechanisms of the two new impregnated cathodes are discussed reasonably.