X-ray Production

• What is the purpose of the filament and cathode?

  Produces an electron steam.
• What is the purpose of the anode?

  A high positive potential to the cathode, therefore it attracts the electrons.
• What is the purpose of the target?

  It is made of tungsten embedded in the anode block, here the electrons interact to produce x-rays.
• What is the purpose of the evacuated glass envelope?

  It is evacuated so that nothing impedes the electron flow and would damage the filament.
• What are the characteristics of the anode target?

  • Most commonly used material is tungsten.
  • May be alloyed with rhenium to prevent pitting.
  • Molybdenum is used in mammography units due to its characteristics radiation being of a suitable energy.
• What are the characteristics of the anode?

  • The focused electron beam will be attracted towards the + anode.
  • The electrons are accelerated to very high velocity, gaining kinetic energy.
  • They strike the target of the anode which produces x-ray photons.
• Why should we use tungsten as a target?

  • High melting point ($3380^{\cdot C}$).
  • Reasonable thermal conductivity.
  • Electrical conductor.
  • It has a high atomic number Z = 74 which results in efficient x-ray production.
• What is the effect of the atomic number of x-ray production?

  • The target material of the anode will produce x-radiation most successfully if it has a high atomic number.
  • The atomic number of a material is an indication of the number of protons in the nuclei of the atoms of that material.
  • The higher the atomic number, the greater the number of positive protons in the nucleus and more attractive it is to passing electrons.
• How are x-rays produced?


  X-rays are produced when rapidly moving electrons that have been accelerated through a potential difference of order 1 kV to 1 MV strikes a metal target.