Cyclotron is used to accelerate

A cyclotron is a device by which the positively charged particles like proton,

 deuteron etc., can be accelerated. The working of cyclotron is based on the fact that a

  positively charged particle can be accelerated to a sufficiently high energy with the help of

   smaller values of oscillating electric field by making it to cross the same electric field time

      and again with the use of strong magnetic field.