210 research outputs found
Piecewise acceleration of electrons across a periodic solid-state structure irradiated by intense laser pulse
Three-dimensional particle-in-cell simulations show that the periodic
solid-state structures irradiated by intense ( W/cm) laser
pulses can generate collimated electron bunches with energies up to 30 MeV (and
acceleration gradient of GeV/cm), if the microstructure period is equal
to the laser wavelength. A one-dimensional model of piecewise acceleration in
the microstructure is proposed and it is in a good agreement with the results
of numerical simulations. It shows that the acceleration process for
relativistic electrons can be theoretically infinite. In the simulations, the
optimal target parameters (the width of the microstructure elements and the
microstructure period) are determined. The explored parameters can be used for
proof-of-principle experiments demonstrating an ultrahigh gradient acceleration
by a number of identical and mutually coherent laser pulses [A. Pukhov et al.,
Eur. Phys. J. Spec. Top. 223, 1197 (2014)]
Radiative Losses in Plasma Accelerators
We investigate the dynamics of a relativistic electron in a strongly
nonlinear plasma wave in terms of classical mechanics by taking into account
the action of the radiative reaction force. The two limiting cases are
considered. In the first case where the energy of the accelerated electrons is
low, the electron makes many betatron oscillations during the acceleration. In
the second case where the energy of the accelerated electrons is high, the
betatron oscillation period is longer than the electron residence time in the
accelerating phase. We show that the force of radiative friction can severely
limit the rate of electron acceleration in a plasma accelerator.Comment: 17 pages, 5 figure
Control of laser wake field acceleration by plasma density profile
We show that both the maximum energy gain and the accelerated beam quality
can be efficiently controlled by the plasma density profile. Choosing a proper
density gradient one can uplift the dephasing limitation. When a periodic wake
field is exploited, the phase synchronism between the bunch of relativistic
particles and the plasma wave can be maintained over extended distances due to
the plasma density gradient. Putting electrons into the th wake period
behind the driving laser pulse, the maximum energy gain is increased by the
factor over that in the case of uniform plasma. The acceleration is
limited then by laser depletion rather than by dephasing. Further, we show that
the natural energy spread of the particle bunch acquired at the acceleration
stage can be effectively removed by a matched deceleration stage, where a
larger plasma density is used
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