Lecture 3: The Betatron And Cyclotron

Question 1

What is the betatron?

Answer 1

A particle accelerator that uses induction through a donut-shaped tube to accelerate the particles.

Question 2

How does the betatron accelerate particles?

Answer 2

The strength of the magnetic field is varied cyclically in time. This is done by passing an alternating current through the primary coils that generate the field.

Question 3

Particle acceleration occurs during the _____ quarter of the voltage cycle that generates the magnetic field for a betatron.

Answer 3

First

Question 4

The guide field for a betatron must be ____ the average field threading the loop.

Answer 4

Half

Question 5

What limits the betatron from reaching high particle energies?

Answer 5

Losses from synchrotron radiation.

Question 6

What are betatrons historically used for?

Answer 6

Particle physics experiments to generate hard (high energy) x-rays.

Question 7

What is a cyclotron?

Answer 7

A particle accelerator consisting of 2 ‘Dees’ across which an alternating voltage is applied.

Question 8

How does the cyclotron accelerate particles?

Answer 8

Each time a particle passes between the Dees it is accelerated as is it attracted to the oppositely charged side. An alternating voltage is applied so the Dees swap charges at a given frequency.

Question 9

What happens to the particles in the cyclotron when they gain energy?

Answer 9

They spiral outwards.

Question 10

What is the equation for the frequency of the cyclotron?

Answer 10

f = frequency
T = time period
B = magnetic field
q = charge
m = mass