1. why is there a vacuum in the light tube, in addition to preventing the oxidation of tungsten wire. Is there anything else?
Of course。 If it is not a vacuum, the electrons collide with the gas in the tube and prevent the electrons from reaching the anode.
2. why tungsten wire is used as an electronic emission source. Are there any special requirements for the current of the filament?
The melting point of tungsten wire is high, and the electronic work work is not very good. If the melting point is low, it will fuse. The higher the temperature of the tungsten wire, the larger the electron emission will be. I think there is no special requirement for the filament current, as long as it can make the filament heat and light not as far as it is to fuse.
3. the main thing is how to choose the target! Can you give a list of the characteristics of a different target
(1) select according to the needs. As for the list, you can investigate the physical nature of the matter of interest.
(2) why are the target materials chosen for molybdenum and rhodium? Can other objects be okay?
Anything else can be. The basic principle is to select the anode target according to the need. For example, what kind of object you want to study. For example, if you want to study the X ray of a substance, you must of course choose the substance. If you are not interested in X ray itself, but about X ray hit other substances caused by the effect, so choose your basic principle is the following: 1) the metal, so that has a high potential anode, is conducive to the anode to electronic poly 2) melting point is not too low, otherwise the electrons hit to the target of the target temperature lead to melting. 3) whether X ray energy or wavelength is suitable for your research. For example, the number of the anode target atoms is too low and the X - ray energy is too low, and some of your requirements may not reach. 4) the information of the target itself, such as the price is not too expensive, non-toxic and so on. The X ray energy released by molybdenum and rhodium is moderate, which basically reaches the above index. 5) voltage problem. If the voltage of the X - ray tube is low, the electron hits the anode target of the high atomic number and does not excite the K layer X ray. At this point, it may be bad for your research goals.
4. what is the statement of the anode voltage and current?
When the voltage is too low, the electronic kinetic energy is too small to excite X rays when the electrons hit the target.
The high voltage may lead to the breakdown of the X - ray tube. Of course, this problem has been taken into account when it is designed, and it will not appear. But too high voltage is sometimes unnecessary. Increase the burden and danger.