CYCLOTRON

Principle

Charge particle can be accelerated to large kinetic energy by making it pass through a high frequency electric field and again by using strong magnetic field

Construction and working

Let a charge particle placed in between 2 dees subjected to electric field and magnetic field simultaneously. If the dee D1, that -ve potential then the particle will be attracted towards D1.Due to presence of magnetic field the charge particle will cover similar path and move again the gap.

The potential difference of AC source is adjusted in such a way that time taken by the particle to cover one semicircle across the dees must be equal to half the time period of oscillator. When the charge particle reaches the gap the polarities of the dees automatically reverses.

Now the particle will again cover semicircle through D2 and reach the empty space again .

The velocity of particle increase every time it reaches the gap. After the continuous process when the particle reaches near the edge of the dees system, the reflecting plate P1 and P2 reflect the charge particle through a window and hits the target.

Theory

The Magnetic Lorentz force acting on the positively charge q and mass m is given by the relation

Fm = q (V*B)

Fm = qVB

The Magnetic Lorentz force provides necessary centripetal force to the particle to move in a circular path of radius ‘r’.

Fm = Fc

qVB = mV²/r

r = mV/qB

V = rqB/m

Hence, the output energy of the particles is given by the expression

E = q²B²r²/2m

Uses of cyclotron

For several decades, these were the best sources of high-energy beams for nuclear physics experiments. However, these are still in use for this type of research.

PRESENTED BY –

Lopamudra Behera( Lect. In Physics)