摘要:
磁控注入式电子枪能提供高导流系数的电子注,可应用于大功率微波管中。但是,通常认为这种电子枪属于交叉场型的,具有交叉场器件固有高噪声的特性。这使它的应用受到了限制。 有两个实验打破了上述这种看法。1962年C波段低噪声行波管应用磁控注入式电子枪获得了3.1dB的噪声系数。1965年S波段中功率前向波放大器获得了3.5dB的噪声系数。但这些器件均限于中小功率范围,阴极长度很短,即阴极长径比很小的情况;而对于大功率管中使用的磁控注入式电子枪,能否获得足够小的噪声系数的问题,尚有待于进一步深入研究。 本文简要讨论了影响大功率微波管中磁控注入式电子枪噪声的主要因素以及通过改变阴极区磁场分布的方法来减小噪声的实验结果。
Abstract:
The magnetron injection gun is able to provide a beam of high perveance to be used in high power microwave tubes. But usually this kind of gun is regarded as of the crossed-field type, and has the characteristic high noise found in erossed-field devices. This limits its use.There have been experiments that negated such views. In 1962, a C-band low noise T. W. T. used a magnetron injection gun and obtained a noise figure of 3.1dB. Again in 1965, a S-band forward wave amplifier of medium power obtained a noise figureof 3.5dB. But these devices are all limited to low or medium powers, the cathode length is quite short, i.e. the ratio of cathode length to cathode diameter is quite small. using the magnetron injection gun in a magnetron of high power whether we can obtain small enough noise figure is still a problem needing further investigation. In this paper, a discussion of chief factors that influence the noise of magnetron injection guns in a high power magnetron and adoption of a method of changing the distribution of magnetic field around the cathode in order to reduce noise are made. Experimental results of guns adopting this method are presented.
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