Particle accelerators
Cyclotron
A cyclotron has two D-shaped chambers (knowns as 'dees') which are in a strong vertical magnetic field.
- The protons are injected into the centre and are accelerated by the voltage between the dees.
- The protons move in a semicircular path due to the magnetic field round one dee until they cross the gap again and are accelerated by high voltage again. This time the polarity of voltage has been reversed to accelerate the protons in the opposite direction.
- As the protons travel faster, their radius around the dees increases until finally they are ejected as a high speed proton beam.
A cyclotron can be used to make short-lived radioisotopes (radioactive atoms) that can be used for medical imaging and research.
Other particle accelerators which involve the use of fields on charges include synchrotrons and linear accelerators.
All particle accelerators have the following in common:
- Electric Fields are usually used to increase the speed of the particles.The force is constant in a uniform electric field so the particles are accelerated in a straight line.
- Magnetic Fields are used to control the direction of particle beams. The force when cutting a magnetic field acts perpendicular to the direction of travel of the particle and therefore changes as the particle travels in a circular path.
- Very fast and therefore high-energy particles then collide with a stationary target or other moving particles to disintegrate and reveal their internal composition.
