^Production of X – rays

^Production of X – rays

If the fast electrons incident on entering a heavy target (a metal piece of high atomic weight & high melting point) X-rays are produced.

Coolidge tube is used in the production of X-rays. It is a hard glass evacuated tube (EGT). One end of the tube has a tungsten filament emitting fast moving electrons (also called cathode rays), while the other end contains the heavy target (HT).

A p.d. » 20 kV is maintained between the cathode and a metallic target accelerates the electrons toward the latter.  In the Coolidge tube it is necessary to maintain vacuum of high order (P = 106 cm of Hg) so that the electrons may not lose energy due to the collisions with gas atoms. Majority part of the KE of the incident electrons is wasted in heating the anode & hence the X-ray production requires targets with high melting such as tungsten. Also cooling of target is required. The efficiency of production of X-rays less than 1%.

X-rays are produced by following two mechanisms

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