The key difference between cyclotron and betatron is that cyclotron uses a spiral path, whereas betatron uses a circular path for accelerating charged particles.
Cyclotron and betatron are two types of particle accelerators. Cyclotron is the earliest form of the accelerator, while betatron is modern compared to it. Both these systems use magnetic fields and electric fields for the acceleration.
CONTENTS
1. Overview and Key Difference
2. What is Cyclotron
3. What is Betatron
4. Side by Side Comparison – Cyclotron vs Betatron in Tabular Form
5. Summary
What is Cyclotron?
Cyclotron is a type of particle accelerator which is used to accelerate charged particles using a spiral path. This device is useful for charged atomic or subatomic particles. The founder of this device is Ernest Orlando Lawrence.
When considering the design of a cyclotron, it contains two hollow semicircular (spiral) electrodes. These electrodes are known as dees. And, these two electrodes are mounted back to back and are placed in an evacuated chamber between the poles of a magnet.
When considering the method of operation, it has an electric field which is alternating in its polarity. The particles that need to be accelerated are formed near the centre of the device. Here, the electric field propels the particles into the dees. Also, there is a magnetic field that guides the particles in a semicircular path. With time, the particles are accelerated from one dee to the other.
Figure 01: Method of Operation of a Cyclotron
However, this device can accelerate protons with energies less than 25 million eV. Therefore, it is a major limitation to this device. In order to overcome this limitation, we can vary the frequency of alternating voltage impressed on the dees. Then the device is called a synchrocyclotron.
What is Betatron?
Betatron is a type of particle accelerator that is modified mainly to accelerate beta particles or electrons. This device uses an electric field and a magnetic field for the acceleration. The particles are accelerated in a circular orbit.
Figure 02: A Betatron
When considering the structure of a betatron, it contains an evacuated tube. This tube is made into a circular loop, and it is embedded in an electromagnet. The windings of the electromagnet are parallel to the circular tube. Here, an alternating electric current tends to produce a varying magnetic field that periodically reverses in direction. The electron acceleration is affected by two forces: force acting in the direction of the motion and force acting in right angles to the direction of the motion. These two forces are important in maintaining the circular path of the electron in the loop.
What is the Difference Between Cyclotron and Betatron?
Cyclotron is a type of particle accelerator which is used to accelerate charged particles using a spiral path. Betatron is a type of particle accelerator that is modified mainly to accelerate beta particles or electrons. The key difference between cyclotron and betatron is that cyclotron uses a spiral path, whereas betatron uses a circular path for accelerating electrons.
Moreover, another difference between cyclotron and betatron is that cyclotron contains two electrodes called dees mounted back to back while betatron contains an evacuated tube which is made into a circular loop and this loop is embedded in an electromagnet. When considering the method of operation, in a cyclotron, charged particles are accelerated from one dee to the other due to the effect of electric field and magnetic field. In betatron, the electrons are accelerated due to the action of two forces: force acting in the direction of the motion and forces acting in right angles to the direction of the motion.
Below infographic shows more comparisons related to the difference between cyclotron and betatron.
Summary – Cyclotron vs Betatron
Cyclotron and betatron are two types of particle accelerators. The key difference between cyclotron and betatron is that cyclotron uses a spiral path, whereas betatron uses a circular path for accelerating charged particles.
Reference:
1. “Cyclotron.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 8 Feb. 2018, Available here.
2. “Cyclotron.” Hyperphysics, Available here.
3. “Cyclotron.” Wikipedia, Wikimedia Foundation, 11 Mar. 2020, Available here.
Image Courtesy:
1. “Cyclotron diagram” By Unknown author – Retrieved November 3, 2014 from Radio-Craft, Radcraft Publications, Springfield, Massachusetts, Vol. 18, No. 9, June 1947 p. 23 on American Radio History archive (Public Domain) via Commons Wikimedia
2. “Melbourne University 35MeV Betatron” By Suzie Sheehy – Own work (CC BY-SA 4.0) via Commons Wikimedia