The Röntgen Radiation and its application in studies of ... - Mansic

2. The production of X-rays
The X rays, that are currently being used for different purposes, can be obtained
with help of the X-ray tube. The X-ray tube is a vacuumed space (10 -6 torr) inside
of which there are two electrodes, a hot cathode (tungsten filament) and an
anode between which a 10 ÷ 200 kV voltage is applied. The electrons emitted by
the filament are accelerated due to the voltage differential and when they hit the
anode X radiation is emitted. Because through the collision with the anode over
98% from the energy of incoming electrons is turned into heat (the rest consist of
energy radiated as X-rays), the anode has to be water cooled (Figure 2) [2]. For
higher power (5 ÷ 60 kW) of X-ray radiation, the tube equipped with rotating
anode is in use. On the X-ray tube used for structural studies, the electrons
emitted by the filament are focused, only on a rectangular surface of the anode
(tubes with Gotze linear focal point).
Figure 2. The scheme of the tube with rotating anode
Figure 3. The principle of X-ray diffraction [3]
3. X-ray spectrum - continuous and characteristic
Roentgen radiation, produced with the help of X-ray tubes, is the result of the
accelerated electrons interaction with the atoms from surface of the anode. There
are two types of interactions that lead to the apparition of a continuous spectrum
or a characteristic spectrum [4].
a. The continuous spectrum. An electron that moves at a high speed can be
decelerated when pass near of atom nuclei. As a result of this interaction the
Physics of Advanced Materials Winter School 2008 5