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
how to compute the fourier series expansion of a rectangular pulse train

Particles of mass M and m separated in space by a distance R exert a mutually attractive gravitational force F on one another given by where G is the universal gravitationa

A synchronous generator has a rotor with six poles and operates at 60 Hz. (a) Determine the speed of prime mover of the generator. (b) Repeat part (a) if the generator has 12

Q. A rectangular loop is placed in the field of an infinitely long straight conductor carrying a current of I amperes, as shown in Figure. Find an expression for the total

Q. Multi-link connection in a network of register? For a multi-link connection in a network of register- controlled exchanges, a register in originating exchange receives addre

We can use Ampere's Law to calculate the magnetic field in the core.

Earth Leakage : Earth leakage takes place when, through some fault in an appliance or its connections. Electric current escapes to earth i.e. the body of the appliance become 'liv

what happens when the resistors have different values

Magnetic field due to an electric current   Let a piece of wire be arranged to pass vertically by a horizontal sheet of cardboard, on which is placed few iron filings.  If a curr