Cyclotrons, Synchrotrons, and Rings

For many years, filament and PIG ion sources were placed in the center of the cyclotrons. However, the development of more complicated and powerful ion sources such as the ECR sources required more space than was available at the center of the machines. Present-day cyclotrons have external ion sources and a low-energy beam from an electrostatic injector is threaded into the center via an axial channel and inflector or via a radial channel in separated- sector machines (described below). 

The time, tcyc, that it will take a particle to complete one orbit is the circumference divided by the velocity  

A number of attempts were made to develop cyclotrons that could accelerate protons up to energies on the order of a GeV (the proton rest mass). For example, the resonant frequency of the cyclotron could be decreased in proportion to the mass increase. Such a frequency-modulated (FM) cyclotron (synchrocyclotron) 

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