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Cyclotron (1)
1.
2. Cyclotrons accelerate charged particles using
a high-frequency,
alternating voltage (potential difference). The
cyclotron was invented by Leo Szilárd and
first manufactured by Ernest Lawrence
3. A positively charged particle can be
accelerated to high energy with the help of
an oscillating electric field, by making it
cross the same electric field time and again
with the use of a strong magnetic field.
4.
5. D1 and D2 are hollow evacuated metal chambers
called dees . The dees are connected to a high
frequency oscillator. The two dees are enclosed in
a evacuated steel box. The box is placed in a
strong magnetic field produced by two pole pieces
of electromagnet.
6.
7. The positive ion to be accelerated is placed in
between the dees. Let D1 is at negative potential and
D2 is at positive potential. The ion will be
accelerated towards D1
On reaching inside D1 the ion will be in field free
space(electric field is zero).Due to perpendicular
magnetic field it describes a semi circular path inside
D1 of radius r=mv/Bq.
8. Time taken by the ion to cover semi circular path is t=
πm/Bq. This time is independent of speed of the ion
and radius of its path.
The time during which positive ion describe a semi
circular path is equal to the time of half cycle of electric
oscillator and at the same instant polarity of the dees
are reversed.
Now D1 becomes positive and D2 becomes negative.
The ion is accelerated towards D2. It enters D2 by
crossing electric field between D1 and D2 therefore inside
D2 it describes semi circular path of greater radius
(velocity increases due to electric field).
As time period is independent of speed and radius
therefore the ion will arrive in the gap when the polarity
of the dees is reversed.
therefore, positive ion will go on accelerating every time
it comes in the gap between the dees.
The accelerated ion can be removed out of the dees
from window , by applying electric field.
9.
10. For several decades, cyclotrons were the best
source of high-energy beams for nuclear physics
experiments.
several cyclotrons are still in use for this type of
research.
Cyclotrons can be used to treat cancer. Ion beams
from cyclotrons can be used, as in proton therapy,
to penetrate the body and kill tumors by radiation
damage.
This device is a mass spectrometer
that uses ion cyclotron resonance(ICR).
11. A positive ion can not be accelerated beyond
a certain limit because with the increase in
velocity mass of the charge particle
changes. which changes the time period of
circular path and positive ion will not arrive
in the gap between the dees exactly at the
instant when polarity of the dees are
reversed.
12. Electron can not be accelerated using
cyclotron because the mass of electron is
small and small increase in energy of
electron provide high speed to the
electron and electrons go quickly out of
step with the oscillating electric field.
The uncharged particles like neutron can
not be accelerated using cyclotron.
