Grades 6–8 · Systems
How do particle accelerators add energy and steer a beam?
A particle accelerator gives charged particles high energies so researchers can study matter and its interactions. A source supplies particles such as electrons or protons. They travel through a beam pipe with very little gas, reducing unwanted collisions with air molecules.
In the diagramElectric fields add energy; magnets steerPositive particle+10 keVElectricstage20 kVMagnetic bendDirection changesGain: 20 keVLeaves at 30 keVMagnetic steering adds 0 keV in this ideal model
An electric field can push a charged particle along its motion and transfer energy to it. An electronvolt is the energy gained by one elementary charge crossing a one-volt accelerating potential; kilo means a thousand. Here a positive particle with one elementary charge crosses 20 kilovolts and gains 20 kiloelectronvolts, or keV. Starting with 10 keV, it leaves with 30 keV. This describes energy gained, not a claim that speed increases by the same proportion.
Magnetic fields have a different job. For a moving charge, magnetic force acts sideways to its instantaneous velocity. It can bend the path or help focus a beam, but that force alone does not add kinetic energy. The diagram’s optional bend therefore changes the direction while keeping the selected energy.
Linear accelerators send particles through successive stages. Circular machines can return a beam to accelerating regions repeatedly. Radiofrequency electric fields must be timed to the arriving particle bunches, and magnets must guide the changing beam. Detectors then measure what happens when a beam meets a target or another beam.
About this explanation
Starting knowledge: Know that particles can have electric charge and that energy and motion direction are different quantities.
Sources
- US Department of Energy — How Particle Accelerators Work
- CERN — How an accelerator works