explain the construction and working principle of a coolidge tube?
Answers
SjThe principle of x-ray tube operation. When the filament is fed with the heating current, it emits electrons. They are attracted and accelerated in the direction of the anode (~ 20 mm).
PLZ MARK IT as the BRAINLIEST
Without a doubt, the single most important event in the progress of radiology was the invention by William Coolidge in 1913 of what came to be known as the Coolidge x-ray tube. Nevertheless, despite its clear superiority, the Coolidge tube did not immediately replace cold cathode tubes - the latter continued to be manufactured into the 1920s and saw routine use into the 1930s. In fact, there were instances of cold cathode tubes being employed in radiology as late as the 1960s!
The characteristic features of the Coolidge tube are its high vacuum and its use of a heated filament as the source of electrons. There is so little gas inside the tube that it is not involved in the production of x-rays, unlike the situation with cold cathode gas discharge tubes.
The operation of the Coolidge tube is as follows. As the cathode filament is heated, it emits electrons. The hotter the filament gets, the greater the emission of electrons. These electrons are accelerated towards the positively charged anode and when the electrons strike the anode, they change direction and emit bremsstrahlung, i.e., x-rays with a continuous range of energies. The maximum energy of the x-rays is the same as the kinetic energy of the electrons striking the anode. In addition to the x-rays produced at the focal spot of the anode, some undesirable x-rays (stray radiation) are produced by electrons striking other tube components.
The key advantages of the Coolidge tube are its stability, and the fact that the intensity and energy of the x-rays can be controlled independently. Increasing the current to the cathode increases its temperature. This increases the number of electrons emitted by the cathode, and as a result, the intensity of the x-rays. Increasing the high voltage potential difference between the anode and the cathode increases the velocity of the electrons striking the anode, and this increases the energy of the emitted x-rays. Decreasing the current or the high voltage would have the opposite effects. The high degree of control over the tube output meant that the early radiologists could do with one Coolidge tube what before had required a stable of finicky cold cathode tubes. As a bonus, the Coolidge tube could function almost indefinitely unless broken or badly abused.