What is Cyclotron?

A cyclotron is a type of particle accelerator. Cyclotrons accelerate charged particles using a high-frequency, alternating voltage (potential difference). A perpendicular magnetic field causes the particles to spiral almost in a circle so that they re-encounter the accelerating voltage many times.

Ernest Lawrence, of the University of California, Berkeley, is credited with the development of the cyclotron in 1929, though others had been working along similar lines at the time.

FUNCTIONS:

Cyclotrons have a single electrical driver, which saves both money and power, since more expense may be allocated to increasing efficiency.
Cyclotrons produce a continuous stream of particles at the target, so the average power is relatively high.
The compactness of the device reduces other costs, such as its foundations, radiation shielding, and the enclosing building. 

Construction of Cyclotron

The cyclotron magnet components

Here is a photo of the magnet wire and the core that will be used to make an extremelly compact electromagnet for the cyclotron.

Electromagnetic coil construction
Ahh this is my first attempt at winding a one of the electromagnetic coils for the cyclotron. I am using 14AWG high temp magnet wire for this coil. The construction of the coil is very messy and time consuming. I made it by figuring out the best geometry for the coil considering the ammount of available room on the core. Then I built a coil form and began wrapping wire, taping, and varnishing it.

The Finished Coils
Here is a photo of the finished electromagnetic coils. As you can see I installed water cooling lines that are made out of 1/4 in copper tubing. I did this because the magnetic coils are made from 14AWG wire which will get extremelly hot from the 40amps/40vDC that will be running through it. Keep in mind it's using 1500 watts of DC power.

Working of Cyclotron

The charged particle (say a positively charged proton) is released near mid point of the face of one of the Dees. Being in the electric field from one Dee to another, it is accelerated by the electric force in the direction of electric field. As the particle enters the adjoining Dee, the magnetic force, being perpendicular to it, renders the charged particle to move along a semicircular path within the Dee.   By the time, it emerges again in the narrow gap separating the two Dees, the electrical polarity of Dees changes so that the particle is again accelerated again with an increase in speed. 

But as the speed of the particle has increased, the radius of curvature of the semicircular path increases in accordance with the formula :



  r = mv/Bq   ( where B is magnetic field , m is mass , v is velocity , q is charge )


For given charge, mass and magnetic field, the radius is proportional to the speed. Clearly, the charged particle begins to move in a larger semicircular path after every passage through the gap. By the time particle reaches the gap successively, electric polarity of Dees keeps changing ensuring that the charged particle is accelerated with an increase in speed. This process continues till the charged particle reaches the periphery and exits through the guide with high energy and bombards a given target being investigated. The description of different segments of the path of accelerated particle is given here :


1: Path is a straight line. Particle is accelerated due to electric force. Speed and kinetic energy of the particle increase.


2: Path is a semicircular curve. Particle is accelerated due to magnetic force. This acceleration is centripetal acceleration without any change in speed and kinetic energy of the particle.


3: Path is a straight line. Particle is accelerated due to electric force in the direction opposite to the direction as in case 1. Speed and kinetic energy of the particle increase by same amount as in the case 1.


4: Path is a semicircular curve of greater radius of curvature due to increased speed. Particle is accelerated due to magnetic force. This acceleration is centripetal acceleration without any change in speed and kinetic energy of the particle.


5: Path is a straight line. Particle is accelerated due to electric force in the direction opposite to the direction as in case 1. Speed and kinetic energy of the particle increase by same amount as in the case 1 or 3.



We see that the particle follows consecutive larger semicircular path due to increase in the speed at the end of semicircular journey. The resulting path of charged particle, therefore, is a spiral path – not circular.

Limitations of Cyclotron

* Cyclotron cannot accelerate uncharged particles like neutrons.

* Cyclotron cannot accelerate electrons because of its small mass.

* It cannot accelerate positively charged particles with large mass due to relativistic effect. 

Uses of Cyclotron

The cyclotron is used to bombard nucli with energetic particles, so accelerated by it  and study the resulting nuclear reaction. It is also used to implant Ions into Solids and modify their properties or even synthesis new materials it is used in hospitals to produce radioactive substance which can be used in diagonosis and Treatment.