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Page history last edited by Marwan 9 years, 2 months ago


Rafae, Salik, Marwan







A little History of the Cyclotron...





     In the early 1930s, the acceleration of electrons and protons was a popular project.

In 1928, Lawrence was hired as an Associate Professor of Physics at the University of California. An attempt in 1930 by Northwestern University to lure Lawrence away led Berkeley to promote him to full professor at the age of 29, becoming the youngest Professor at the University of California. There, he was called the "Atom Smasher", and the man who "held the key" to atomic energy.

E. O. Lawrence and his graduate students at the University of California, Berkley tried many different configurations of the cyclotron before they met with success in 1929. The earliest cyclotron was very small, using electrodes, a radio frequency oscillator producing 10 watts, a vacuum, hydrogen ions, and a 4 in (10 cm) electromagnet. Lawrence's original cyclotron design was limited to energies where relativistic effects were not important.


     Lawrence was acquainted with the problem of high-voltage acceleration through Tuve's work. In spring 1929 he got an idea for a new way of accelerating particles. He was browsing a German electrical engineering journal, not the most common reading for a physicist. A Norwegian engineer, Rolf Wideröe, had published a sketch of a device that allowed one to use the same electrical potential twice, doubling the energy by switching from positive to negative potential in order to push ions and then to pull them. Lawrence thought to use a magnetic field to bend charged particles into circular trajectories and thus pass them through the same accelerating region over and over again. The idea required a combination of sophisticated techniques: a high-vacuum chamber with electric fields varying at radio frequencies and with some means to keep the particles in a single horizontal plane. The first model of Lawrence's cyclotron was made out of brass, wire, and sealing wax and was only four inches in diameter—it could literally be held in one hand. It accelerated hydrogen ions up to energies of 80,000 electron volts. It probably cost $25 in all. In summer 1931 an eleven-inch cyclotron achieved a million





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How it works!





Cyclotron is a modern tool which is used in experiments which deal with particle acceleration. Basically, the purpose of a cyclotron is to make subatomic charged particles move at very high speeds, almost to that of the speed of light! Cyclotrons make use of a combination of electric and magnetic fields and circular motion to achieve this. A proton beams are created by cyclotrons.


A cyclotron comprises of two large D-shaped magnets separated by a small gap which is a vacuum space. And an electric field is passed through the space of the two magnets. The current supply is AC in order to alternate the polarity of the magnets simultaneously. The particles are injected in centre of this arrangement so that it follows the magnetic field [A circular path] and gradually it increases its velocity as it goes round and round.


     The particle keeps accelerating as it moves in a spiral-like path. The perpendicular magnetic field combined with the increasing energy of the particles forces the particles to travel in a spiral path. The magnetic field is also slowly increased. This prevents the particle from keeping enough momentum to maintain a circular orbit. The larger the the magnetic field the faster the particle moves. In addition to this, energy is applied to the particles as they cross the gap between the two magnets and so they are accelerated and will increase in mass as they approach the speed of light. Either of these effects (increased velocity or increased mass) will increase the radius of the circle and so the path will be a spiral. As the particle reaches its desired velocity it then escapes the cyclotron in the form of a proton

beam and is targeted as to what our application demands.



Cyclotron Application      






     Modern day applications for cyclotrons include uses for medicinal purposes as well as for further research in nuclear physics.

In terms of medicine, cyclotrons can be used to treat cancer. Ion beams from cyclotrons can be used to penetrate a patient’s body and to ensure the healthy tissues are not damaged during the process.

Scientists also use the concept of the cyclotron in order to study more about the universe and to find answers to question regarding to how the universe came to creation. They are using cyclotrons to collide atoms at very high speeds.





Test Question:


How does the AC supply maintain the spiral-like movement of the charged particle that our subjects in the cyclotron and explain what would happen if we replaced the AC supply with a DC supply instead?











Cyclotron Videos!
























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