Cyclotron, Definition, Working and Principle of Cyclotron, Application of Cyclotron (For CBSE, ICSE, IAS, NET, NRA 2022)

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  • It can be defined as a type of particle accelerator in which charged particles accelerate outwards from the centre along a spiral path.
  • These particles are held to a spiral trajectory by a static magnetic field and accelerated by a rapidly varying electric field.
Static Magnetic Field
  • It was one of the earliest types of particle accelerators, and is still used as the first stage of some large multi-stage particle accelerators.
  • It makes use of the magnetic force on a moving charge to bend moving charges into a semicircular path between accelerations by an applied electric field.
  • The applied electric field accelerates electrons between the β€œdees” of the magnetic field region.
  • The field is reversed at the cyclotron frequency to accelerate the electrons back across the gap.

Working and Principle of Cyclotron

Working and Principle of Cyclotron
  • It accelerates a charged particle beam using a high-frequency alternating voltage which is applied between two hollow β€œD” -shaped sheet metal electrodes called β€œdees” inside a vacuum chamber.
  • Dees are placed face to face with a narrow gap between them, creating a cylindrical space within them for the particles to move.
  • So, the particles are injected into the centre of this space.
  • The magnetic field causes the path of the particles to bend in a circle due to the Lorentz force perpendicular to their direction of motion.
    • Betatron
    • Synchrotron
    • Electroscope

Application of Cyclotron

For several decades, these were the best sources of high-energy beams for nuclear physics experiments. However, these are still in use for this type of research.

Treatment of Cancer

Using the ion beams from cyclotrons can be used to penetrate the body and kill tumours by radiation damage; Cyclotrons can be used in particle therapy to treat cancer.

Cyclotron Frequency

The frequency is given by:


  • q is the charge of the particle,
  • B is the magnetic field used in the cyclotron,
  • M is the mass of the charged particle.
  • Consider a particle of charge q revolving in the path of radius r with a velocity v.
  • Now for the circular motion we can write:
  • Centripetal force = Lorentz force due to magnetic field B
  • So,

Limitations of Cyclotron

  • It cannot accelerate electrons because electrons are of very small mass.
  • It cannot be used to accelerate neutral particles.
  • It cannot accelerate positively charged particles with large mass due to the relativistic effect.

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