Electron beam devices

An electron beam device consists of at least three main parts:

• An electronic searchlight (gun ^[4] ) forms an electron beam (or a beam of rays, for example, three rays in a color picture tube) and controls its intensity (current);
• A deflecting system controls the spatial position of the beam (its deviation from the axis of the spotlight);
• The target (screen) of the receiving EBL converts the energy of the beam into the luminous flux of the visible image; A target of a transmitting or storing ELP accumulates a spatial potential relief , read by a scanning electron beam ^{[1] [3]} .

Reception CRTs are divided according to the method of deflection and focusing of the electron flux (electron beam), the duration of the afterglow of the screen and design parameters.

By the method of focusing and beam deflection, CRTs are divided into:

• magnetically controlled tubes - a magnetic field is used to focus and deflect the beam
• electrostatic deflection tubes - an electric field is used to focus and deflect the beam
• in some cases (in picture tubes ) combined beam control is used: electrostatic focusing and magnetic beam deflection

One of the main parameters characterizing a CRT is the screen afterglow duration - the time during which the screen brightness after removing the beam decreases to 1% of the original.

According to the afterglow duration, the following types of CRT are distinguished:

• with very short afterglow - less than 10 ^-5 sec
• with a short afterglow - from 10 ^-5 to 10 ^-2 sec
• with an average afterglow - from 10 ^-2 to 10 ^-1 sec
• with long afterglow - from 10 ^-1 to 15 sec
• with very long afterglow - over 15 sec

Tubes with a long afterglow are often used in radar technology, since the period of the change of images in the radar indicators can reach tens of seconds or more.

This tube consists of three elements:

• electronic spotlight creating a narrow electron beam directed along the tube
• deflecting system
• fluorescent screen to indicate the position of the electron beam

Electronic Spotlight

It consists of: cathode (4), control electrode (3), first (5) and second (6) anodes

• The cathode is designed to create an electron flow. In a CRT, an indirect cathode is usually used in the form of a cylinder, inside of which there is a heater. The active (emitting) layer is applied only to the bottom of the cylinder, so the cathode has a flat emitting surface and the electrons are emitted by a narrow beam in the direction of the screen.
• a control electrode (modulator) is designed to adjust the brightness of the light spot on the screen (10). The electrode is also made in the form of a nickel cylinder surrounding the cathode. The bottom of the cylinder is made in the form of a disk with a diaphragm with a diameter of <1 mm, through which electrons emitted by the cathode pass. Due to the small diameter of the diaphragm, electrons whose trajectories deviate from the normal to the cathode surface do not pass through the diaphragm and do not participate in beam formation.
• the first anode is also a cylinder with two (three) diaphragms. The influence of the control electrode and the first anode on the electron beam current is similar to the influence of the control ("first") grid and the anode on the anode current in the EEC . The beam current and, consequently, changes in the brightness of the light spot on the screen of the tube are controlled by applying a small negative voltage to the cathode to the control electrode.
• the second anode is made similarly to the modulator and the first anode, but of a larger diameter than the first anode. Since the second anode is accelerating, a higher voltage relative to the cathode is applied to it (1 kV - 20 kV)

Rejecting System

To move the light spot across the screen, between the second anode and the screen there is a deflecting system of two pairs of mutually perpendicular plates. The plates (9) are horizontally deflecting, because a horizontal electric field is created between them, that is, when voltage is applied to them, the beam will deviate in a horizontal plane towards a positively charged plate. If a periodically changing voltage is applied to the plates, the light beam will move in different directions, leaving a trace in the form of a horizontal line on the screen. The plates (8) are vertical deflecting, because a vertical electric field is created between them.

Based on the foregoing, if voltage is applied simultaneously to both pairs of plates, then the beam will draw a line on the screen that depends on the voltage on the plates of the deflecting system. ^[five]

Fluorescent screen

For visual observation of the screen glow during the bombardment of a CRT screen, it is coated with a phosphor - capable of luminescing . The brightness of the glow depends on the speed of the electrons, the current density and the properties of the phosphor.

Phosphors determine the color and duration of the screen glow.

Transmitting electron beam devices convert an optical image into an electrical signal.

• The dissector (“instantaneous tube”) is historically the first type of transmitting tube used for astronomical observations, in industrial automation devices and for scanning documents ^[6] ;
• An iconoscope is historically the first type of transmitting television tube;
• Ortikon , superortikon , vidicon - the main types of transmitting tubes ^[7] used in television before switching to solid state converters ;
• Specialized devices, for example, a monoscope - a tube for converting into a electrical signal the only (hence the name of the device) image formed inside the tube during the manufacturing process - usually a test chart .

Reception electron beam devices convert an electrical signal into an optical (visible) image:

• Oscillographic tube - ELP with electrostatic beam deflection, used to visualize the shape of electrical signals;
• Kinescope - a receiving tube of a television system with a magnetic deflecting system and a horizontal scan of the image;
• A quantoscope (laser kinescope) is a type of kinescope whose screen is a matrix of semiconductor lasers pumped by an electron beam. Quantoscopes are used in image projectors .
• Indicator cathode ray tube - a receiving tube of a radar system with a magnetic deflecting system and a circular scan, as well as a variety of specialized indicators, sign-generating tubes, etc. ^[8] ;
• Sign-generating (sign-printing) tubes (characterron, taypotron and their analogues);
• The storage tube records information on a spatial target, stores it for a predetermined time, and (in tubes with reading) reproduces or reads it by an electron beam. Various tubes of this subclass were used both for storing, processing, and reproducing optical images, as well as binary storage devices of early computers ^[9] .
• A cadroscope is a cathode ray tube with a visible image, designed to configure scan units and focus the beam in equipment using cathode ray tubes without a visible image (grafcons, monoscopes, potentioscopes). The cadroscope has a pinout and attachment dimensions similar to the cathode ray tube used in the equipment. Moreover, the main CRT and the cadroscope are selected according to the parameters with very high accuracy and are delivered only as a kit. When setting up, instead of the main tube, a framescope is connected.

Listed below are the largest manufacturing companies of EBLs (in alphabetical order) as of the end of the 20th century ^{[ significance of fact? ] [10]} :

• Handbook of elements of electronic devices / ed. V.N.Dulina, M.S. Zhuka. - M .: Energy, 1978.
• Katsnelson B.V., Kalugin A.M., Larionov A.S. Electrovacuum electronic and gas-discharge devices. - M .: Radio and communications, 1985.
• Electronics: Encyclopedic Dictionary / V. G. Kolesnikov (editor-in-chief). - 1st ed. - M .: Sov. Encyclopedia, 1991 .-- S. 54. - ISBN 5-85270-062-2 .
• Sherstnev L.G. Electronic Optics and Electron Beam Devices. - M .: Energy, 1971. - 368 p.
• Zhigarev A. A. Electronic Optics and Electron Beam Devices. - M .: Higher school, 1972. - 540 p.
• R.A. Lachashvili, L.V. Traube. Design of electron beam devices. - M .: Radio and communications, 1988 .-- 217 p. - ISBN 5-256-00039-X .
• Kalashnikov A.M. Stepuk Ya.V. Vacuum and semiconductor devices. -M .: Military Publishing, 1973.- 292 p.

• Electron beam devices - an article from the Great Soviet Encyclopedia .