Electron beam focused to a fine spot, Electrical Engineering

Q. How is the electron beam focused to a fine spot on the face of the CRT?

Sol. The functional diagram of an electrostatic focusing arrangement is shown below. The pre-accelerating anode, which is a metal cylinder containing many baffles, collimates the electron beam which enters it through a small opening on the left hand side. The pre-accelerating anode is connected to a high positive potential.

The focusing anode and the accelerating anodes are co-axial with the pre-accelerating anode. The pre-accelerating and accelerating anodes are connected to the same potential while the focusing anode is connected to a lower potential.

On account of difference of potential between focusing anode and the two focusing anode. The equipotential surfaces thus form a "double concave".

The electron beams entering the field at angles other than the normal to the equipotential surfaces, will be deflected towards the normal and the beam is thus focused towards the centre of the tube axis. By changing the voltage of the focusing anode, the refractive index of the electron lens is changed and therefore the focal point of the beam can be changed. The change in voltage is brought about by chanting the setting of potentiometer. This control is brought to the front panel of CRO and is marked focus.

 

 

Posted Date: 7/12/2012 6:17:05 AM | Location : United States







Related Discussions:- Electron beam focused to a fine spot, Assignment Help, Ask Question on Electron beam focused to a fine spot, Get Answer, Expert's Help, Electron beam focused to a fine spot Discussions

Write discussion on Electron beam focused to a fine spot
Your posts are moderated
Related Questions
what is ohm?

i need matlab codes for the minimum cell cost method to start the initial feasible solution and the stepping stone method to find the optimum value


Develop and execute a program to analyze the circuit shown in Figure (a), and use PROBE for plotting v C (t).

Q. Do the following operations with 8 bit bytes, and indicate the condition of the overflow and carry bits. a) 10111011 + 00000011 b) 11101101 + 11111001 c) 11011011 + 110

Explain P - N junction. P - N junction: If a p- type semiconductor is properly joined to an n-type semiconductor the contact surface that formed is termed as p-n junction. Th

What is the use of terminal count register? Each of the four DMA channels of 8257 has single terminal count register. This 16-bit register is used for ascertaining that the dat

What is hall effect?

What are the different types of write operations used in 8253? There are two types of write operations in 8253 (1) Writing a control word register (2) Writing a count val

A circular ring of magnetic material has a mean length of 1m and a cross sectional area of .001m^2.A sawcut of 5mm width is made in the ring . calculate the magnetizing current req