磁聚焦法测量电子荷质比实验理论探究

Theory Study on Measuring Electronic Specific Charge Experiment by the Magnetic Focusing Method

根据电荷在磁场中的运动特点,分析了电子束的磁聚焦原理,推导了测量电子荷质比的计算公式,探讨了决定荧光屏上亮线段的因素并由此解释了亮线段一边旋转一边变短的原因.结果表明亮线段的长度和方向与磁场、电子速度和从原点到荧光屏的距离等因素有关.最后分析了产生实验误差的主要原因.

Based on moving trait of the electric charge in magnetic field,the theory on magnetic focusing of the electron beam is analyzed;the calculating expressions of electronic specific charge is educed.The factor of deciding the line on screen is discussed,thereout the reason of bright line one side circumrotating at the same time shortening,the result making know the line’s length and direction relating to magnetic field,electron speed and the distance from origin to screen,etc.Finally main reasons of experiment error are analyzed.