The carbonizing process and its influence on the thermionic electron emission properties of Mo-La_2O_3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C_6H_6 are ke...The carbonizing process and its influence on the thermionic electron emission properties of Mo-La_2O_3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C_6H_6 are key factors of the carbonizing process. The carbonized ratio of Mo-La_2O_3 cathode increases with the increase of carbonizing temperature at low temperature. The highest carbonized ratio is 19.7% obtained at 1723 K, then the carbonized ratio decreases rapidly if temperature increases further. The carbonized ratio increases with the prolongation of carbonizing time during the process of first 6 min., after that the carbonization ratio changes little with the time increase, and the carbonized ratio increases with the increase of the C_6H_6 pressure when the pressure is low, the maximum carbonized ratio reaches 19.7% at 1.5×10^(-2) Pa, then the carbonized ratio goes down sharply when the C_6H_6 pressure is over 1.5×10^(-2) Pa. The emission properties at different operated temperatures and the emission current stability of FU-6051 tubes (equipped) with Mo-La_2O_3 cathodes were also studied in the article. The study results indicate that the emission can keep stable only when the operating temperature is from 1700 to 1800 K and the carbonized layer must be composed by Mo_2C only. The FU-6051 tubes (equipped) with Mo-La_2O_3 cathodes have excellent stable emission current and the lifetime exceeds 3000 h when the cathode′s carbonized ratio is 19.7% operated at 1773 K.展开更多
文摘The carbonizing process and its influence on the thermionic electron emission properties of Mo-La_2O_3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C_6H_6 are key factors of the carbonizing process. The carbonized ratio of Mo-La_2O_3 cathode increases with the increase of carbonizing temperature at low temperature. The highest carbonized ratio is 19.7% obtained at 1723 K, then the carbonized ratio decreases rapidly if temperature increases further. The carbonized ratio increases with the prolongation of carbonizing time during the process of first 6 min., after that the carbonization ratio changes little with the time increase, and the carbonized ratio increases with the increase of the C_6H_6 pressure when the pressure is low, the maximum carbonized ratio reaches 19.7% at 1.5×10^(-2) Pa, then the carbonized ratio goes down sharply when the C_6H_6 pressure is over 1.5×10^(-2) Pa. The emission properties at different operated temperatures and the emission current stability of FU-6051 tubes (equipped) with Mo-La_2O_3 cathodes were also studied in the article. The study results indicate that the emission can keep stable only when the operating temperature is from 1700 to 1800 K and the carbonized layer must be composed by Mo_2C only. The FU-6051 tubes (equipped) with Mo-La_2O_3 cathodes have excellent stable emission current and the lifetime exceeds 3000 h when the cathode′s carbonized ratio is 19.7% operated at 1773 K.
