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Cyclotron
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Accelerates particles using alternating electric field and magnetic field.
Particles circulate between two D-shaped electrodes; an alternating electric field accelerates them every half-turn, and the magnetic field keeps them in a spiral of growing radius.
Used for producing medical isotopes.
Final energy K = q²B²R²/2m.
In more detail
A cyclotron accelerates charged particles in a spiral, using an alternating electric field across a gap and a steady magnetic field to keep them circling. Each pass gives the particle a boost of energy.
Real-world uses
- Medical cyclotrons produce radioisotopes for PET scans.
- Cyclotrons are used in cancer therapy with proton beams.
- Medical centres use cyclotrons to produce short-lived isotopes for PET scans.
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Frequently asked questions
Why does the particle speed up?
The electric field across the gap adds energy each time it passes.
What limits a cyclotron?
Relativistic effects increase the particle mass, which breaks the synchronisation.
How does a cyclotron speed up particles?
An electric field across a gap gives a kick each half turn, while the magnetic field bends the particles back into a spiral.
Related topics in Magnetism & Induction
Helical motion · Velocity selector · Mass spectrometer · Force on a current-carrying wire · Force between parallel wires · Definition of the ampere