摘要:
本文首先建立轮辐栅网结构模型,分区计算其屏蔽系数和单个栅格内栅丝半径与该栅格面积之比,结合Spangenberg书中的结论给出了轮辐栅网截止放大系数的新表达式,然后详细地研究了栅丝半径、各环区所对球心角以及径向栅丝数目对截止放大系数的影响,并计算了温度升高之后截止放大系数的变化,最后给出了设计轮辐栅网的步骤和具体实例.结果显示,根据新表达式设计的栅网具有更好的稳定性和可靠性,能够很好地解决平板正方形栅格近似中存在的问题.
Abstract:
Although the grid with film sphere and porous structure plays a very important role in sphere grid-controlled electron gun,its cut-off amplification factor can be obtained only in the plane-square-mesh approximation.Due to the lack of consideration for nonuniformity of cut-off amplification factor and information about cathode half-angle and radius of curvature of grid,the designs of sphere grid and electron gun cannot be related by the plane-square-mesh approximation,which is unusable as theory basis for fabricating thinner grid wires.In this paper,we model the grid with film sphere and porous structure and obtain the new expression for cut-off amplification factor by recalculating the screening factors and the ratios of the radius of grid wire to the area of this single mesh in different ring areas.In combination with the conclusion of cut-off amplification factor given in Spangenberg＇s book,the effects of grid wire＇s radius,sphere center angle and the number of radial grid wires on the cut-off amplification factor,and the variation of the cut-off amplification factor with temperature rising are obtained.Finally,the steps for the design of grid with film sphere and porous structure and some specific examples are presented.The results show that the grid devised by new expression is more stable and reliable,and problems existing in plane-square-mesh approximation are solved.
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