Section II. X-RAY TUBES
X-rays are produced when high-speed electrons undergo a loss of energy in
matter. The loss of energy and subsequent generation of x-rays occurs in one of the
following ways: either the electrons are decelerated, or they collide with atomic nuclei
and orbital electrons. Three conditions are necessary for the production of x-rays:
a. A source of electrons.
b. A means of accelerating the electrons.
c. A hard, dense target in which the kinetic energy of the electrons is converted
For the purpose of simplification, the production of x-rays can be divided into
three steps: (1) the filament in the cathode end is heated by an electric current causing
it to emit electrons (figure 3-6A); (2) high voltage is applied across the x-ray tube to
accelerate the electrons toward the target (figure 3-6B); and (3) the high-speed
electrons are rapidly decelerated by the target, producing x-radiation (figure 3-6C).
Figure 3-6. Production of x-rays.