To Study The Construction Of Stationary Anode X-ray Tube

         X-rays are produced by energy conversion when a fast moving stream of electrons is suddenly deaccelerated in the target anode of an X-ray tube. The X-ray tube is made of pyrex glass that encloses a vaccum containing two electrodes. The electrodes are designed so that electron produced at the cathode ( negative electrode or filament ) can be accelerated by high potential difference towards the anode. Electrode are produced by heated tungsten filament are accelerated across the tube to hit the tungsten target, where X-rays are produced.

GLASS ENCLOSURE

•  It is necessary to seal  the two electrode of the X-ray tube in a vaccum.
• If gas were present inside the tube the electrons that were being accelerated towards the cause   secondary elecrons enjected from the gas molecule.
• By this process additional electrons would be available for accelerated for towards the anode.
• This production of the secondary electrons could not be satisfactorial  controlled.

IONAIZATION

•  This presence would result in variation  in the number and more strikingly in the reduced speed of electron imping on the target.
• This would cause a wide variation in tube current  and in the energy of  x-ray produced. This is called as ionization.
• Actually this principle was used in the gas x-ray tube, which contains small amounts of gas the serve as a source of secondary electron.

CATHODE

• The negative terminal of x-ray tube is called the 'Cathode'.
• Filament is used as the cathode in x-ray tube.
• The filament which is the source of electrons for the x-ray tube. The cathode has two other elements thses are 
• The connecting wire which supply  both voltage(about10v) and current(3-5 A)
• Metallic focusing cup.
• The no of x-ray produced depends on th no. of elctrons.
• The filament is made up of tungsten wire about 0.2 mm in diameter that is coiled to form a vertical spiral about 0.2cm in diameter.

THERMONIC EMISSION

• When metal is heated its atom absorb thermal energy and some of the electrons in the metal acquire enough energy to allow them to move a small distance from surface of the metal .
• This is called as the Thermonic Emission.
• Which may be defined as the emission of electrons resulting from the absorption of thermal energy.

SPACE CHARGE

•  Electrons emitted from the tungsten filament from a small could in the intermediate vicinity  of the filament. This collection of negatively charged electrons is callled as   Space Charge.

 SPACE CHARGE EFFECT   

•  The tendency of the space charge to limit emission of more electrons from the filament is called as the Space Charge Effect. 

 ANODE

Anode is consist of  tungsten or molybdenum electrons emitted from cathode bumbarded on the anode plate and x-ray are produced but 99% energy waste.

PROPERTIES OF X-RAYS

• X-rays are eletromagnetic waves of very short wavelength. 
• They are not detected by an electric field  or a magnetic field.
• It is travel in straight line.
• They affected photographic lines\ plates.
• In air or vaccum, they travel with speed of light.
• They ionise the gas through which they pass.