行波管中多级降压收集极效率评估的研究

摘要

在行波管中，多级降压收集极（MDC）效率由于其与总效率的关系密切而显得非常重要．而在设计MDC之前对其效率和行波管的总效率进行准确的评估可以把握管子的整体性能，并为相关软件的开发提供理论指导，因而对MDC的优化和行波管总效率的提高具有十分重要的意义．虽然Kosmahl在1980年就给出了MDC的效率评估公式，但其预测值比实测值偏高较多，因而需要更为准确的评估公式．本文首先引入耗散公差的概念，然后建立作用完电子注等差三角能量分布模型推导了MDC效率评估的公式，与Kosmahl给出的预测相比，新公式的估计结果更接近实测值．最后根据MDC效率最高和各个电极上耗散能量最低这两个极值条件，给出了MDC最佳电极级数的选取公式，其预测结果合理而且准确．%In a traveling wave tube, efficiency of multistage depressed collector （MDC） is very important because it is closely related to total efficiency. The correct estimate of the efficiencies of MDC and TWT can help us predict TWT′s whole function and provide a theoretical guidance for developing pertinent software, which therefore plays an important role in optimizing MDC and improving TWT total efficiency. Although formula for predicting MDC efficiency was given by Kosmahl in 1980, whose estimation is much higher than the measured value, a more accurate formula is still necessary. Firstly, the concept of ＂dissipated common difference＂ is used in this paper to estimate the efficiencies of MDC and TWT and then new estimate formulas are obtained by making a model of arithmetic triangular energy distribution for spent beam. It is expected that new formulas give predictions closer to the measured values than the Kosmahl＇s evaluation. Finally, expression for optimal MDC electrodes is given on the basis of two extreme values, i.e., maximal MDC efficiency and minimal total dissipated energies on all electrodes. The prediction from the expression is reasonable and accurate.