实验2: 电子受静电力及磁力作用的偏折
(课本实验15/16)
阴极射线管CRT的内部结构
控制栅极G
聚焦阳极F
加速阳极A (总电位V1)
水平偏压(偏折)平行电极板
垂直偏压(偏折)平行电极板
Z方向无偏折之电子束
萤光幕
阴极射线管(CRT)内的加热灯丝
阴极射线管(CRT)内的阴极C
目的: 观察阴极射线管(cathode ray tube, CRT)中之电子束在电场(E)及磁场(B)中之偏折运动情形,并测量电子的荷质比(e/m比)
原理: Lorentz force F = q(E + v x B) [SI unit: N = C·(V/m) = C·(m/s).T]
阴极射线管CRT的内部结构
阴极射线管的工作原理
Operation Principle of CRT
I. 在水平和垂直偏折平行电极板(4,5)无外加偏压信号时:
阴极射线管内的加热灯丝(8)将阴极C(9)加热放出热电子
经控制栅极G(1), 聚焦阳极F(2)及加速阳极A(3)(总电位V1)后
电子往Z方向(6)做等速运动,mvz2/2 = eV1 vz = (2eV1/m)1/2
电子打到萤光幕(XY面)(7)上的中心位置,形成一亮点.
阴极射线管CRT的内部结构
电子质量 m = 9.11 x 10-31 kg
电荷 q = -e = -1.60 x 10-19 C
As V4 = 0 V5 = 0
Commonly used to obtain a visual display of electronic information in oscilloscopes, radar systems, televisions, etc..
Be a vacuum tube in which a beam of electrons is accelerated and deflected under the influence of electric or magnetic fields.
The electrons are deflected in various directions by two sets of plates.
The placing of charge on the plates creates the electric field between the plates and allows the beam to be steered.
Cathode Ray Tube
(CRT)
Cathode Ray Tube (CRT)
- is one of the main elements of an oscilloscope.
A CRT is commonly used to obtain a visual display of electronic information in oscilloscopes, radar systems, televisions, etc.
The CRT is a vacuum tube in which a beam of electrons is accelerated and deflected under the influence of electric or magnetic fields.
The tubes are produced with electrostatic and electromagnetic control, where electrostatic or magnetic fields deviate the electron beam respectively.
The principle scheme of CRT has electrostatic control as well as the motion of the electrons in the beam drawing a sinusoid on the screen of oscilloscope.
Configuration of CRT
CRT consists of 6 sections:
Glass bulb evacuated to a high vacuum (真空管)

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