Cyclotron - History, Working, Uses, Frequency FAQs

What is a Cyclotron?

Normally, a cyclotron is used to accelerate charged particles and ions to high energies. E.O. Lawrence and M.S. Livingston invented it in 1934 to investigate the nuclear structure. As both the fields are perpendicular to each other, they are called cross fields.
A spiral path leads the charged particles from the centre of a cyclotron outward. Static magnetic fields and rapidly varying electric fields keep the particles on a spiral trajectory.

This Story also Contains

1. What is a Cyclotron?
2. Principle of Cyclotron
3. The Cyclotron's Uses of Cyclotron

Cyclotrons produced particle beams in physics and nuclear medicine for most of the 20th century. Cyclotrons are still used today for producing particle beams in physics. It was James Lawrence's 4.67 m (184 in) synchrocyclotron at the University of California, Berkeley that held the world record for the largest single-magnet cyclotron, capable of accelerating protons to 730 mega electron volts (MeV).

The largest of its kind, which can produce high-energy protons at the University of British Columbia in Vancouver, Canada, is the 17.1 m (56 ft) multi-magnet TRIUMF accelerator.

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History

His study of linear accelerators and their patenting led to their invention in 1928. Szilard published the first patent application in Germany in January 1929 giving details of the resonance condition (which would later become known as the cyclotron frequency formula) for circular accelerating apparatuses of the cyclotron.

The first cyclotron, bevatron, and photon accelerator were also invented by him. When Ernest Lawrence read Rolf Wieder’s paper describing drift tube lines a couple of months later, the cyclotron idea crossed his mind.

The device was patented in 1932 after being published in science in 1930. The Federal Telegraph Company provided him with large electromagnets recycling old Poulsen arc transmissions. M. is a graduate student in industrial management.

He took the idea and turned it into real hardware, thanks to Stanley Livingston.

A series of cyclotrons was built at Berkeley's Radiation Laboratory by Lawrence and his collaborators that were the most powerful in the world; the 69 cm (27 in) 4.8 MeV machine (1932), the 94 cm (37 in) 8 MeV machine (1937), and the 152 cm (60 in) 16 MeV machine (1939).

He also created a 730 MeV synchrocyclotron (1945) that measured 467 cm (184 in). The cyclotron and the results achieved with it earned Lawrence, who won the Nobel Prize in Physics in 1939, the prize for his invention and development.

Principle of Cyclotron

An electron beam is accelerated by a cyclotron using a high-frequency alternating current that passes between two hollow "D"-shaped sheet-metal electrodes inside a vacuum chamber.

A cylindrical space is created within the Dees with a narrow gap between them, allowing particles to move between them. Into this space are injected particles.

A static magnetic field B is applied perpendicular to the electrode plane by the electromagnet located between the poles.

Due to the Lorentz force perpendicular to the direction of motion, the magnetic field bends the path of the particle in a circle.

Multiple thousand volts of alternating voltage are applied between the diodes. As a result of the voltage, the particles accelerate due to an oscillating electric field between them.

One circuit is formed during one cycle of voltage, so the frequency of the voltage is set appropriately. Boosting the particle's cyclotron frequency is required to achieve this condition.

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The cyclotron frequency is expressed as

$$
\mathrm{F}=2 \pi \mathrm{~m} / \mathrm{qB}
$$

The magnetic field strength is $B$
The electric charge of a particle is $q$
A charged particle's relativistic mass is $m$

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Numerous forms of the cyclotron have been developed over time

It is believed that the style of cyclotron described in earlier sections, with a constant frequency and uniform magnetic field, has been largely replaced. It had concerns about focusing and was limitations of the cyclotron to totally non-relativistic energies (outputs energy low relative to rest energy).

By decreasing the radio frequency of the oscillator on the Synchrocyclotron as the orbit of the particle grew larger and larger until it was in sync with the particle, it extended energies into the relativistic regime. A powerful accelerator, predating the synchrotron, it was built in the 1950s. Due to its pulsed operation, it had a very low luminosity (beam current).

It uses cyclotron-shaped pole pieces (isocyclotron) to generate a nonuniform magnetic field stronger in peripheral regions to increase the centripetal force acting on the particle as it gains relativistic mass while using alternating gradient focus to keep the beam focused.

This is a term describing machines in which the pole surfaces have hills and valleys as the particles move around the ring, making the field increase and decrease and maintaining beam collimation via alternating gradient focusing.

Generally, the magnets are divided by gaps without fields in a separated sector cyclotron, meaning the machine is divided into sections

It is possible to easily deflect a beam from an H⁺ cyclotron because it accelerates negative hydrogen ions. A metal foil strips the electrons from the hydrogen ions at the beam exit point on the periphery of the Dees, resulting in positively charged H⁺ ions. As a result, the beam leaves the machine after being bent rather than deflected by the magnets.

The Cyclotron's Uses of Cyclotron

Nuclear physics experiments relied on these beams for several decades.

Technologies relevant to this field

Magnetrons are devices for generating high-frequency radio waves (microwaves) using the spiralling of electrons in a cylinder of vacuum. Synchrotrons move particles in a path provided by constant radius, which allows them to be made in the shape of pipes, able to go to greater distances than is practical with cyclotrons and synchrocyclotrons.

In an evacuated pipe, an increased radius permits the use of numerous magnets that impart angular momentum, which in turn holds particles of higher velocity (mass) within the boundaries. Efforts are made to keep the bending angle constant by increasing the strength of the magnetic fields in each bending magnet.

Cancer treatment:

By using cyclotron ion beams to penetrate the body and kill tumours via radiation damage, cyclotrons can be used in particle therapy to treat cancer.

Is the Cyclotron limited in any way?

• Electrons cannot be accelerated by cyclotrons since they have a very small mass.
• Neutral particles cannot be accelerated in a cyclotron.

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