Different Types of Cyclotrons

What is a cyclotron? A cyclotron is a mechanical device that was invented by the American nuclear scientist Ernest O. Lawrence in the year 1929-1930 to speed up a charged particle. The cyclotrons that were made early on were of small size, and later, different dimensions were designed based on the requirement.

Early cyclotrons had many limitations, as they were incapable of accelerating small mass particles like electrons. These limitations of cyclotron were overcome by modulating the conventional cyclotron with modern particle accelerators. There are different types of cyclotrons, such as conventional or classical types of cyclotrons, synchrocyclotrons, isochronous cyclotrons etc.

What are Cyclotrons?

A cyclotron is a mechanical device which is used to speed up a charged particle. These charged particles speed up at a huge rate. This device produces highly energetic particles. An alternating voltage of high frequency is used in a cyclotron to accelerate the charged particle or ions. The applied voltage causes an oscillating electric field in deep space, which helps to accelerate the particles. This device helps us to speed up the charged particles and ions by rotating them in a circular path.

This device was invented and made by American nuclear scientist Ernest O. Lawrence in the year 1929-1930, to accelerate the charged particles for different purposes. This device became a very beneficial device in the upcoming year, and Lawrence received the Nobel prize in physics in the year 1939 for the invention of the cyclotron. The first construction was based on the principle of magnetic resonance accelerators.

Principle of the Cyclotron

The cyclotron is a mechanical device that works on the general principle of the force experienced by particles or ions due to the magnetic field. The force is experienced by the charge due to the interaction of the electric field of charge and the external magnetic field. This force is known as the Lorentz force. Let a charged particle be released from a source having some positive charge. From the property of the interaction of charges (opposite charges attract), this charged particle would attract a negative charge. 

When such particles or ions are kept inside the dees (“D”s) of a cyclotron, then the value of electric field strength on the particle at this position is zero and thus there is no electric field between the dees. If any of the two dees has a negative charge at an instant of time, then the particle gets attracted towards it (let the particle be positive and opposite charges attract) and starts to accelerate. Because of the normal (perpendicular) magnetic field, the moving particle feels both magnetic and electric force (Lorentz force). Here, the Lorentz force acts on the particle, which makes it rotate in a circular path.

Types of Cyclotrons

The cyclotrons were used as particle accelerators when they were invented. With different needs and the limitation of the earliest type of cyclotrons, many changes and modifications were made. There are many types of cyclotrons which are now used for different purposes in different fields. The main types of cyclotrons are listed below.

Conventional Cyclotrons

Conventional or classical type of cyclotrons is the earliest form of cyclotron. It was invented by Ernest O. Lawrence in the year 1929-1930 to accelerate the charged particles for different purposes. In this type of cyclotron, the value of radio frequency of alternating voltage is the same as the value of resolution frequency of the ion or particle placed in the cyclotron.

There are many limitations present in the conventional type of cyclotrons, such as it speeds up the charged particles or ions at a low speed. This limitation was overcome over the years by remodelling this cyclotron.

Synchrocyclotron

Synchrocyclotron is the modulated form of the classical or conventional type of cyclotron. In the conventional type of cyclotron, the particle can not be accelerated to a high speed. This limitation is overcome in this type of cyclotron. The frequency of the electric field is regulated in a synchrocyclotron, which makes this device capable of speeding up the particle at high speeds.

This cyclotron is constructed for small mass particles too. Thus final or the resultant beam is obtained from a very small gap, which restricts the scattering of particles. There is some waiting time before it delivers the particles or the ions placed in the chamber of the cyclotron in a bundled form. 

Isochronous Cyclotron

This is the third type of cyclotron, which is similar to the synchrocyclotron, but the only difference is that the magnetic field of this device changes (grows) with the radius and not with the time period. The little gap of synchrocyclotron is replaced with enough gap so that the beam of resultant particles will be steady and continuous.

The frequency of the isochronous cyclotron is steady for each ion or particle. The area of the magnet of this cyclotron device is large compared to the other cyclotrons, which makes it heavy and costly.

Betatrons

The betatrons are a very special type of cyclotron which generate a very high energy beam of beta particles or electrons of approximately 300 Mev. In the manufacturing industries as well as the medical field, this type of cyclotron is used to produce X-rays.

The main limitation of such a cyclotron is that it works in a steady electric field and changing magnetic field.

Conclusion

The cyclotron was invented to increase the speed of the charged particles. There are many advantages of a cyclotron at the current time, but it had many limitations in the initial phase. To reduce the limitation of cyclotron and increase its efficiency, it is replaced with modern cyclotrons with several modifications over time. At present, there are many kinds of cyclotrons used for different purposes, for example, time conventional cyclotrons, betatrons, synchrotrons, linear accelerators, isochronous cyclotrons etc.