Deflection system
A deflection system deflects charged particle beams (mostly electron beams ) in two or three dimensions in the range of the deflection angle.
In a narrower sense, it denotes the xy deflection in the sense of a Cartesian coordinate system of the image-generating electron beam from television picture tubes and oscillograph tubes (see cathode ray tube ). It consists of deflection plates for the electrostatic deflection of oscilloscope tubes and deflection coils for the magnetic deflection of television picture tubes . In the case of color picture tubes, it also includes the additional coils for achieving the dynamic convergence of the three electron beams.
The maximum possible deflection angle is an important feature: the larger it is, the shorter the picture tube can be. Large deflection angles can only be achieved with magnetic deflection systems; however, the maximum deflection angle change rate is slower than that of electrostatic deflection. Twice the maximum deflection angle is given as the angle specification for characterizing picture tubes; a 90 ° picture tube thus has a maximum deflection angle of ± 45 °.
In radar-vision devices ( surveillance radar ) with cathode-ray tube, the deflection of the electron beam in place polar coordinates instead by
- a deflection coil (sawtooth-shaped current + offset) turned around the tube neck, or
- a fixed pair of deflection coils was fed with currents out of phase with each other by 90 °
Combinations of electrostatic deflection with 2 coaxial cylinders and an orbiting permanent magnetic field were also used in the beginning.
Deflection magnets for the particle beams from particle accelerators are sometimes imposing and sometimes consist of superconducting coils.
Individual evidence
- ↑ http://www.radartutorial.eu/12.scopes/sc15.de.html Block diagram of a radar display device