The property of phosphor to emitt light when its atoms are excited is called fluorescence. When high velocity electron beam structs the phosphorescent screen the light emitts from it. These eliminated the need for the cathode ray tube, using silicon for the photosensitive layer. Which is semitransparant phosphor substance. Schematic diagram of an orthicon video camera tube. The screen consists of a glass which is coated by some florescent material lie zinc silicate. Two pairs of deflection plates provided in the CRT these deflection plates are mounted at right angle to each other to provide electron beam deflection along vertical and horizontal axis of the screen. the focusing anode opperate at a potential of twelve hundred (1200 V) and accelerating anode at 2000 V to accelerate the electron beam. Control grid is bised negative with respect to cathode it controls the density of electron beam to focus the electron beam on the screen focusing anode is used. Heater element is energized by alternating current to obtain high emission of electron from cathode. The electron gun assembly consists of an indirectly heated cathode (K), a control grid (G), an accelerated anode A1, focussing anode A2 and accelerating anode A3 Working of CRT With a phosphorecent screen which produces bright spot when struct by a high velocity electron beam. A cathode ray is defined as a stream of electrons leaving the negative electrode (or cathode) in a discharge tube that contains gas at low pressure or the electrons emitted by the heated filament in certain electron tubes. These are used for controlling the path of the beam. Horizontal and Vertical Deflection Plates These are used for producing a narrow and sharply focus beam of electrons. It is used for producing a strain of electrons 2. They were discovered in around 1870 and were even used by Röntgen himself. Initially this was through the use of what we now call cold cathode, or electrical discharge, tubes, such as the Crookes tube. Introduction The cathode ray tube or 'Braun tube' is a vacuum tube that contains electron guns pointed at a fluorescent screen. Horizontal & Vertical Deflection Plates From the earliest history of X-rays, thermionic emission has been the easiest method to generate the electrons needed within an X-ray tube.The basic CRT consists of four major components. Figure 3: x-ray tube diagram Figure 3: x-ray tube diagram. However, the image will be easily blurred by movement artefacts. A CRT is an electronic tube designed to display electrical data. An X-ray tube can have two filaments at the cathode where a smaller filament produces a smaller focal spot, thus images with greater detail.
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