What is Cyclotron?

We can define cyclotron as a type of particle accelerator in which charged particles accelerate outwards from the center 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.


Cyclotron principle and working of cyclotron

A cyclotron accelerates a charged particle beam using a high-frequency alternating voltage which is applied between two hollow “D”-shaped sheet metal electrodes called “dees” inside a vacuum chamber.

The dees are placed face to face with a narrow gap between them, creating a cylindrical space within them for the particles to move. Then, the particles are injected into the center 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.

Uses 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.

Treat cancer:

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

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 mass of the charged particle.

Consider a particle of charge q revolving in the path of radius r with a velocity v. Now for circular motion:

Centripetal force = Lorentz force due to magnetic field B

i.e., mv2r=qvB

Very= qBm

Therefore Angular velocity (ω) = vr


Time Period (T) =2πω


Cyclotron frequency (n) =1T



What are the limitations of cyclotron?

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

Stay tuned with BYJU’S to learn more about cyclotron, magnetic field, and more with the help of interactive video lessons.

Practise This Question

Which of the following does not represent a distance-time graph?