Ghc. Vanwerkhoven et al., THE INFLUENCE OF HOLE-COUPLING ON THE TRANSVERSE STRUCTURE OF INTRACAVITY LIGHT-PULSES, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 358(1-3), 1995, pp. 304-307
The important issue addressed is the spatial structure of the light pu
lse inside the cavity of a hole-coupled resonator and the fraction of
power lost through the aperture. The radial structure of the radiation
is determined by the competition between power loss and scattering at
the aperture and by the gain due to the interaction with the electron
s. The additional effect of slippage couples the transverse and longit
udinal profiles of the light pulse. It is shown that, at the back of t
he pulse, gain and gain-focussing are dominant. The front of the pulse
propagates mainly in vacuum, The on-axis field intensity in this regi
on is reduced by scattering. The influence of these mechanisms on the
intra-cavity field structure is analyzed using a model that takes the
time-dependent spatial dependence of the optical pulse into account. T
he phenomena are demonstrated numerically for FEL parameters close to
those of FELIX.