Cyclotron auto resonance maser and free electron laser devices: A unified point of view

We take advantage of previous research in the field of cyclotron auto resonance maser ( CARM) and undulator-based free electron laser ( U-FEL) sources to establish a common formalism for the relevant description of the underlying physical mechanisms. This strategy is aimed at stressing the deep analogies between the two devices and at providing a practical tool for their study based on the use of well-tested scaling formulae developed independently for the two systems.