It is a device developed by Lawrence and Livingstone and is used to accelerate charged particles like protons and deuterons. This results in the production of high energy beam which is then used for artificial disintegration, etc.
Suppose a deuteron is at the center of the gap and D1 is at negative potential compared to D2 then deuterons will be accelerated by the electric field between the dees towards D1. Since magnetic field B is perpendicular to the direction of motion of deuteron, a force will act on the particle given by
Consequently, the particle moves along a circular path whose radius is given by
the cyclotron 2 Cyclotron Working Principle
So time period and frequency are independent of the speed of charge and radius of the circular path. If this frequency is equal to the frequency of the oscillator then by the time particle complete half revolution the polarity of the field will change. Deuteron will again be accelerated across the gap, its velocity will increase so that now it will move in a circular path of the greater radius but its frequency will not be affected and the process of acceleration continues.
Cyclotron Working Principle
So the necessary condition for accelerating the deuterons is
cyclotron5 Cyclotron Working Principle
where f0 is oscillator frequency. This is called the resonance condition.
As velocity attained is high, we choose heavier particles e.g., protons, deuterons for acceleration in the cyclotron. The reason is that at such high velocities, mass varies with velocity and f will then depend on velocity, upsetting the resonance condition. This variation in mass is more marked in the case of lighter particles. So cyclotron is suitable only for accelerating heavy particle like protons, deuterons a – particles etc.
Cyclotron in India
Variable Energy Cyclotron Centre (VECC) is located in Calcutta, India. The Centre building itself houses a 224 cm cyclotron, was the first of its kind in India, has been operational since 1977-06-16. It provides proton, deuteron, an alpha particle and heavy ion beams of various energies to other institutions.
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