The following is from Baidu.
X-ray machine is a kind of equipment used to produce X-rays. It can be divided into industrial X-ray machines and medical X-ray machines. Industrial X-ray machines can be divided into hard X-ray machines and soft X-ray machines according to the intensity of rays produced. Diffraction analyzers used for physical and chemical detection belong to soft rays, while hard rays are used to detect large and thick materials. The radiation can be generated by high-voltage electricity, such as 100Kv or 300Kv applied to the X-ray tube, and the generated radiation can penetrate the 5-50 mm steel plate. The electron accelerator method can produce rays that penetrate the steel plate above 100 mm, and the machines using high voltage electricity can be divided into portable machines and mobile machines (fixed machines).
Principle and structure of X-ray machine, Discovery of X-ray 1895 German physicist Roentgen (W.C.R? 0? 0ntgen) When studying the gas discharge phenomenon in cathode ray tube, a sealed glass tube with two metal electrodes (one is called anode and the other is called cathode) is used, and tens of thousands of volts are applied at both ends of the electrodes, and the air in the glass tube is pumped out by an air extractor. In order to cover the light during high voltage discharge (an arc lamp), the glass tube is covered with a layer of black cardboard. When he was doing this experiment in a dark room, he happened to find a piece of cardboard soaked in barium platinum cyanide solution emitting bright fluorescence two meters away from the glass tube. Further experiments show that cardboard, wooden boards, clothes and books with a thickness of about 2000 pages can't stop this fluorescence. Even more surprising, when I reached for this fluorescent cardboard with my hand, I saw an image of a hand bone on it. At that time, Roentgen decided that it was a kind of invisible ray, but it could penetrate the object. Because we can't explain its principle and don't know its nature, we borrowed the "X" which represents the unknown in mathematics.
The code name is "X-ray" (or simply X-ray or X-ray). This is the discovery of X-ray and the origin of its name. Industrial X-ray machine uses this characteristic to generate rays by using the high voltage applied by high-voltage transformer to two metal electrodes. X-ray machine is an indispensable equipment for nondestructive testing in aerospace, petroleum construction, natural gas pipelines, boilers, pressure vessels and so on. Industrial X-ray machines are divided into circumferential directions, such as H in figure 1 and "Q" in figure 2. Emit light 360 degrees in the circumferential direction. The direction is 60 degrees to emit light. In addition, there are high and low voltages. The range is from 10 kV to 450 kV. The higher the kV voltage, the greater the radiation intensity.
abstract
Electromagnetic radiation with a wavelength between ultraviolet and gamma rays. It was discovered by German physicist W.K. Roentgen in 1895, so it is also called Roentgen ray. Ultra-hard x-rays with wavelength less than 0. 1 angstrom, hard x-rays with range of 0. 1 ~ 1 angstrom, and soft x-rays with range of1~1angstrom. X-rays are produced by X-ray tubes in the laboratory. X-ray tube is a vacuum tube with cathode and anode. The cathode is made of tungsten wire, which can emit hot electrons when energized, and the anode (called target electrode) is made of high melting point metal (generally tungsten, and the X-ray tube used for crystal structure analysis can also be made of iron, copper, nickel and other materials). Electrons are accelerated by high voltage of tens of thousands of volts to hundreds of thousands of volts, and the electron beam bombards the target electrode, emitting X-rays from the target electrode. When electrons bombard the target, it will produce high temperature, so it is necessary to cool the target with water, and sometimes the target is designed to rotate.
[Edit this paragraph] function
X-rays are characterized by short wavelength and high frequency, and the wavelength is about (20 ~ 0.06) × 10-8 cm. Therefore, X-rays must be produced by atomic transition between two energy levels with very different energy levels. Therefore, the innermost electron of an atom emits X-ray spectrum when it transitions, and the outer electron emits spectrum when it transitions. X-rays will not deflect in electric and magnetic fields. This shows that X-ray is an uncharged particle flow, so it can produce interference and diffraction phenomena.
X-ray spectrum consists of continuous spectrum and labeled spectrum. The marker spectra overlap on the background of continuous spectra. Continuous spectrum is bremsstrahlung caused by high-speed electrons being blocked by the target, and its short-wave limit λ 0 is determined by accelerating voltage V: λ 0 = hc /( ev) is Planck constant, e is electron quantity, and c is the speed of light in vacuum. The identification spectrum consists of a series of linear spectra, which are produced by the transition of electrons in the inner layer of the target element. Each element has a specific set of identification spectra, which reflects the shell structure of atoms. Synchrotron radiation source can produce high-intensity continuous spectrum X-rays and has become an important X-ray source.
X-rays have strong penetrating ability, and can penetrate many substances that are opaque to visible light, such as ink paper, wood and so on. This invisible ray can make many solid substances emit visible fluorescence, make the photographic film sensitive and ionize the air. The shorter the wavelength, the greater the energy of X-rays, which is called hard X-rays. The longer the wavelength, the lower the energy, which is called soft X-rays. When high-speed electrons bombard a metal target in vacuum, the target emits X-rays, which is the structural principle of an X-ray tube.
[Edit this paragraph] Classification
The emitted x-rays are divided into two categories:
(1) If the energy of the electrons blocked by the target does not exceed a certain limit, only a continuous radiation spectrum will be emitted. This kind of radiation is called bremsstrahlung, and the properties of continuous spectrum have nothing to do with the target substance.
(2) A discontinuity with only a few special linear spectra. This linear spectrum of radiation is called characteristic radiation, and the characteristic spectrum is related to the target material.
[Edit this paragraph] Application
Medical diagnostic X-ray machine Medical X-ray machine is one of the commonly used auxiliary examination methods in medicine. X-ray examination methods commonly used in clinic include fluoroscopy and radiography. X-ray is more economical and convenient, and the inspected parts can be changed at will for observation in many aspects, but no objective records can be left, and it is difficult to distinguish the details. Photographing can clearly show the structure of the examined part on the X-ray film, and can be kept as an objective record for a long time, so as to make comparison at any time when necessary. When necessary, special X-ray examination can be carried out, such as tomography, waveform recording photography and contrast examination. The choice of X-ray examination method must be based on the specific conditions of examination, the requirements for solving diseases (especially orthopedic diseases [1]) and clinical needs. X-ray examination is only one of the clinical auxiliary diagnosis methods.
Used for industrial flaw detection. Long-term exposure to X-ray radiation is harmful to human body. X-ray [2] can excite fluorescence, ionize gas and make photosensitive latex sensitive, so X-ray can be detected by ionization meter, scintillation counter and photosensitive latex sheet. Crystal lattice structure can produce significant diffraction effect on X-ray, and X-ray diffraction method has become an important means to study crystal structure, morphology and various defects.
[Edit this paragraph] Found that
1895165438+1October 8th is a Friday. In the evening, the whole campus of Wü rzburg University in Munich, Germany was immersed in a quiet atmosphere, and everyone went home for the weekend. But there's another room with a light on. In the light, a scholar over 500 years old is staring at a pile of gray-black photographic films in a daze, as if lost in thought. ...
What's he thinking? It turns out that this scholar has done discharge experiments before. In order to ensure the accuracy of the experiment, he wrapped all kinds of experimental equipment with tin foil and cardboard in advance, and used cathode tubes without aluminum windows to let cathode rays pass through. But now, he was surprised to find that a screen coated with barium cyanoplatinum emitted by cathode rays (this screen was used in another experiment) gave off light. And the pile of negatives that were tightly closed next to the discharge tube has now turned gray-black-this shows that they have been exposed!
This phenomenon that ordinary people will soon ignore has attracted the attention of this scholar and aroused his strong interest. He thought: the change of the negative film just shows that the discharge tube has released a new kind of penetrating ray, which can even penetrate the bag containing the negative film! Be sure to study it carefully. However-because we don't know what it is, we named it "X-ray".
So the scholar began to study this mysterious X-ray.
He first put a screen coated with fluorescent powder near the discharge tube and found that the screen immediately glowed. Then, he tried to take some opaque substances, such as books, rubber sheets and wooden boards, and put them between the discharge tube and the screen to block the invisible mysterious rays, but no one could stop them. There is almost no shadow on the screen, and you can even easily penetrate 15mm thick aluminum plate! It was not until he put a thick metal plate between the discharge tube and the screen that the shadow of the metal plate appeared on the screen-it seems that this ray still has no ability to penetrate too thick material. The experiment also found that only lead plate and platinum plate can make the screen non-luminous, and when the cathode tube is opened, the photosensitive film placed next to it will also be illuminated, even if it is wrapped with thick black paper.
Then something even more amazing happened. One night Roentgen came home very late, and his wife came to see him in the laboratory, so his wife became the first person to leave traces on the photographic film under the action of unknown radiation. When Roentgen asked his wife to cover the negative with her hand, he took the first X-ray. After being developed, the couple saw images of phalanges and wedding rings on the negative.
This discovery is of great value to medicine. It is like giving people a pair of "glasses" that can see things through the skin, so that doctors can "see" through human flesh and bones and clearly observe various physiological and pathological phenomena in the living body. According to this principle, people later invented the X-ray machine, and X-ray became an indispensable weapon in modern medicine. People accidentally fell, in order to check whether they broke, don't they all go to the hospital to "take a picture" first? This is taking pictures with X-rays!
Although the scholar discovered X-ray, people at that time, including himself, didn't know what it was. It was not until the beginning of the 20th century that people realized that X-rays were actually electromagnetic waves shorter than light waves. It is not only widely used in medicine, but also a powerful weapon for human beings to overcome many diseases, and it also provides important evidence for major changes in physics in the future. It is for these reasons that this scholar became the first person in the world to win the Nobel Prize in physics at the Nobel Prize awarding ceremony in 190 1.
To commemorate Roentgen, people named X-rays Roentgen rays.