The X-ray of the security x ray machine was discovered in 1895 by the German professor Roentgen. This kind of radiation emitted by a vacuum tube that can penetrate objects has stronger energy than visible light in the electromagnetic spectrum, shorter wavelength and higher frequency. Similar radiations include cosmic rays, X-rays, etc.
X-ray tube must be used to produce X-Ray, and the basic structure of X-ray tube must have:
Cathod filament (Cathod)
Evacuated glass envelope
Of course there must be a power supply
X-ray is an electromagnetic wave with a very short wavelength. The wavelength range is 0.0006～50nm. The X-ray wavelength range commonly used in X-ray security inspection is 0.008～0.031nm (equivalent to 40～150kV). In the electromagnetic radiation spectrum, it lies between gamma rays and ultraviolet rays, and has a much shorter wavelength than visible light, which is invisible to the naked eye.
Radiography mainly uses the penetrability of radiation, fluorescence effect and photographic effect
X-ray interacts with objects
1. The photoelectric effect
2. Compton scattering (incoherent scattering)
3. Rayleigh scattering (coherent scattering)
4. Electron couple effect
The procedure of X-ray generation is to first switch on the power supply, pass through the step-down transformer, and heat the X-ray tube filament to generate free electrons and gather near the cathode. When the step-up transformer provides high-voltage electricity to the two poles of the X-ray tube, the potential difference between the cathode and the anode increases sharply, and the free electrons in the active state are strongly attracted, causing the bunch of electrons to travel from the cathode to the anode at a high speed. , Hit the atomic structure of the anode tungsten target. Energy conversion occurs at this time, of which about 1% of the energy is formed into X-rays, and the remaining 99% is converted into thermal energy. The former is mainly emitted from the X-ray tube window, and the latter is emitted by the heat dissipation facility.