2 research outputs found
Transverse self-fields within an electron bunch moving in an arc of a circle
As a consequence of motions driven by external forces, self-fields (which are
different from the static case) originate within an electron bunch. In the case
of magnetic external forces acting on an ultrarelativistic beam, the
longitudinal self-interactions are responsible for CSR (Coherent Synchrotron
Radiation)-related phenomena, which have been studied extensively. On the other
hand, transverse self-interactions are present too. At the time being, existing
theoretical analysis of transverse self-forces deal with the case of a bunch
moving along a circular orbit only, without considering the situation of a
bending magnet with a finite length. In this paper we propose an
electrodynamical analysis of transverse self-fields which originate, at the
position of a test particle, from an ultrarelativistic electron bunch moving in
an arc of a circle. The problem will be first addressed within a two-particle
system. We then extend our consideration to a line bunch with a stepped density
distribution, a situation which can be easily generalized to the case of an
arbitrary density distribution. Our approach turns out to be also useful in
order to get a better insight in the physics involved in the case of simple
circular motion and in order to address the well known issue of the partial
compensation of transverse self-force.Comment: 23 pages, 14 figure
Coherent radiation reaction effects in laser-vacuum acceleration of electron bunches
The effects of coherently enhanced radiation reaction on the motion of
subwavelength electron bunches in interaction with intense laser pulses are
analyzed. The radiation reaction force behaves as a radiation pressure in the
laser beam direction, combined with a viscous force in the perpendicular
direction. Due to Coulomb expansion of the electron bunch, coherent radiation
reaction effects only occur in the initial stage of the laser-bunch interaction
while the bunch is still smaller than the wavelength. It is shown that this
initial stage can have observable effects on the trajectory of the bunch. By
scaling the system to larger bunch charges, these effects may be increased to
such an extent that they can suppress the radial instability normally found in
ponderomotive acceleration schemes, thereby enabling the full potential of
laser-vacuum electron bunch acceleration to GeV energies.Comment: 31 pages, 4 figure