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Applications of charged particles in electric and magnetic fields - Coggle…
Applications of charged particles in electric and magnetic fields
Mass spectrometers
Used to determine the masses of nuclei and to identify the substances/components of a sample
Functioning:
A sample is injected in a vacuum chamber, vaporised and ionised.
An electric field is used to accelerate the nuclei.
Velocity selection produces a single beam of particles that enters a magnetic field.
The magnetic field of the accelerating particles interacts with the permanent magnetic field causing deflection of the particles due to a centripetal force.
The heaviest particles are deflected the least and the lightest particles the most.
By measuring the radius of deflection against a calibration sample the mass of the nuclei can be determined, using: r =mv/qb
Velocity selection
Uses a combination of perpendicular electric and magnetic fields to only allow particles with a certain velocity to pass through a small hole in a device such as a mass spectrometer. .
for particles to pass through the small opening.
Types of particle accelerators
Linacs
Structure and operation
A linac is made up of series of cells in a pipe-shaped vacuum chamber.
The cells increase in length further down the beamline as the particles will travel a greater distance in the same time as they begin to accelerate.
As a charged particle enters a cell from the previous cell the current oscillates to set up an electric field that will once again accelerate the particle.
Linacs produce x-rays and high-energy electrons that are used in oncology – the treatment of patients with cancer.
Linacs are also used as particle injectors for other accelerators such as the synchrotron.
Cyclotrons
Structure and operation
A cyclotron consists of two dees (metal electrodes) with a gap between them inside a vacuum chamber.
A charged particle is placed in the gap between the two dees initially and then accelerated by the use of electric and magnetic fields in a spiral path outward from the centre.
The magnetic field is perpendicular to the path of the electron.
The magnetic field and electric field are responsible for the centripetal force that causes the rotation of the particle.
The electric field oscillates to always have an attractive force on the particle and accelerate it across the gap between the dees.
Each time the particle accelerates from one side to the other its speed increases until eventually it leaves the dee through a gap and is guided towards a target.
Synchrotrons
Structure and operation
Before particles enter a synchrotron they are accelerated using a pre-accelerator such as a Linac as indicated in the image below.
Thereafter, the particle is further accelerated through the use of accelerating cavities that apply an electric field and magnetic fields that deflect the particles in a circular path to accelerate them along the loop.
With each revolution along the cyclic path the particles move faster.
Importance
Synchrotrons are important for the study of sub-atomic physics as the collisions within it can produce new and exotic particles.
The radiation produced is much brighter than any other source and thus makes it incomparable for the study of molecular and crystal structures.
Uses of radiation
Study of molecular and crystal structures related to condensed matter physics, structural biology, environmental science and cultural heritage.
Particle accelerators
o Electric fields are used to speed up particles, whilst magnetic fields are used to direct (contain) streams of charged particles.
o Particles are accelerated to speeds close to the speed of light and then smashed together to produce new and exotic subatomic particles along with beams of light in some cases.
o This provides information about elementary particles, their forces and their motion in relation to the laws of physics as well as produces light that are used for studying the structure of matter and for medical applications.
Why are high energies needed in particle accelerators?
o To produce new and exotic particles in accelerators, the particles need high energies before they collide.
o During collisions, this energy can then be converted into mass according to
