电子管工作时的热状态既是电状态的条件又是电状态的结果,热状态还通过微观的晶格和宏观的胀缩积累引起形变和应力而影响焊缝的气密性。一些大型发射管阴极发射寿命终了之前的早期失效往往是由于电子管设计中对热状态注意不够、处理不好(或使用中由于冷却或其他故障破坏了正常的热状态)的缘故。热状态设计不合理的主要表现是管芯过热——金属(钼)栅极温度过高,表现为栅放偏大或使用过程中早期热碰极;更严重的例子如十多年前用金属钼栅试制的FU-109Z和FM-16Z,只加额定灯丝电压时的栅极热放射就大得使管子下不了排气台。这个失败的经验说明, The thermal state of the tube is not only the condition of the electrical state, but also the result of the electrical state. The thermal state also affects the airtightness of the weld by deformation and stress caused by the micro-lattice and macroscopic expansion-contraction accumulation. The early failure of some large launch tubes before their cathode launch end is often due to inadequate attention to thermal conditions in the tube design, poor handling (or, in use, the normal thermal condition being destroyed by cooling or other failures). Unreasonable thermal design is the main performance of the die overheating - metal (Molybdenum) gate temperature is too high, the performance of the gate is too large or hot early use of the process; more serious example more than a decade ago with metal Mo-grid trial production of FU-109Z and FM-16Z, only the rated filament voltage when the gate heat radiation is so large that the tube can not under the exhaust station. This failure of experience shows that,