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Particle Accelerator
Particle accelerators
• It is a device that provides
– forces on charge particles – by some combinations
of electric & magnetic fields,
– and brings the ions to high speed & kinetic energy
A particle accelerator is a device that uses
electromagnetic fields
to propel charged particles to high speeds and
to contain them in well-defined beams.
Two basic classes of accelerators,
1. Electrostatic accelerators &
2. Oscillating field accelerators
Electrostatic accelerators
1. Electrostatic accelerators use static electric
fields to accelerate particles.
A small-scale example of this class is the cathode
ray tube [CRT] in an ordinary old TV set.
Other examples are the Cockcroft–Walton generator and the
Van de Graaf generator.
The achievable kinetic energy for particles in
these devices is limited by electrical
breakdown.
Oscillating field accelerators
2. Oscillating field accelerators, use radio
frequency electromagnetic fields and
circumvent the breakdown problem.
This class, which was first developed in the
1920s, is the basis for all modern accelerator
concepts and large-scale facilities
Apps.
Particle accelerators are used in a large variety
of applications,
• best known use in particle physics as colliders
(e.g., LHC [Large Hadron Collider] in CERN,
RHIC, Tevatron),
• including particle therapy for oncological
purposes,
• and as synchrotron light sources for fields
such as condensed matter physics.
Oscillating field particle accelerators
• Linear particle accelerators:
– In a linear accelerator (linac), particles are
accelerated in a straight line with a target of
interest at one end.
– They are often used to provide an initial lowenergy kick to particles before they are injected
into circular accelerators.
– The longest linac in the world is the Stanford
Linear Accelerator, SLAC, which is 3 km (1.9 mi)
long. SLAC is an electron-positron collider.
– Linear accelerators are also widely used in
medicine, for radiotherapy and radiosurgery.
• Circular or cyclic accelerators:
– Here, particles move in a circle until they reach
sufficient energy.
– The particle track is typically bent into a circle using
electromagnets.
– The advantage of circular accelerators over linear
accelerators (linacs) is that it allows continuous
acceleration, as the particle can transit indefinitely.
– It is smaller than a linac of comparable power (i.e., a
linac would have to be extremely long to have the
equivalent power of a circular accelerator).
• Cyclotrons:
– The earliest operational circular accelerators were
cyclotrons, invented in 1929
• Betatrons:
– Another type of circular accelerator, invented in
1940 for accelerating electrons, is the Betatron
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