Search

In this note we explore the conditions under which synchrotron radiation can be used to trigger a photocathode gun. We show that such a solution offers in principle the possibility of operating with a pulsed electron beam filling all the buckets of the accelerating radio frequency. Some comments on the e-beam characteristics are also presented.

In this paper we present simple and general formulae for the FEL gain in the pulsed regime including both the longitudinal mode coupling and the lethargy effect. Such relations, obtained from a numerical integration of the pulse propagation equations, are then compared to similar expressions obtained analitycally in the limiting case of the long bunch approximation and the agreement is shown to be excellent.

In this paper we present a simple parametrization of the effects of gain degradation induced in high-current FELs by the inhomogeneous broadenings due to the energy spread and emittances of the electron beam. The parametrization is based on a fitting procedure of the numerical data. The accuracy of the fit is better than 1%.

In this work we show that the basic FEL-Cerenkov dynamics can be modelled using a pendulumlike equation in close analogy with the FEL undulator case. The analysis, including the inhomogeneous broadening effects, is worked out in the hypothesis of single-slab geometry. Two-dimensional motion dynamics effects are also included.

The theory of the free-electron laser dynamics operating in a storage ring is reconsidered within the framework of an analytical treatment. It is pointed out that the dynamical behaviour can be characterized by the round trip evolution of self-reproducing optical field configurations (the supermodes) which allow the understanding of the laser spectral and spatial features. Simple expressions for the threshold gain and for the system efficiency are also derived.