186 research outputs found
The slingshot effect: a possible new laser-driven high energy acceleration mechanism for electrons
We show that under appropriate conditions the impact of a very short and
intense laser pulse onto a plasma causes the expulsion of surface electrons
with high energy in the direction opposite to the one of propagation of the
pulse. This is due to the combined effects of the ponderomotive force and the
huge longitudinal field arising from charge separation ("slingshot effect").
The effect should also be present with other states of matter, provided the
pulse is sufficiently intense to locally cause complete ionization. An
experimental test seems to be feasible and, if confirmed, would provide a new
extraction and acceleration mechanism for electrons, alternative to traditional
radio-frequency-based or Laser-Wake-Field ones.Comment: File RevTex, 12 pages, 8 figure
Propagation of ultrastrong femtosecond laser pulses in PLASMON-X
The derivation is presented of the nonlinear equations that describe the
propagation of ultrashort laser pulses in a plasma, in the Plasmon-X device. It
is shown that the Plasmon-X scheme used for the electron acceleration uses a
sufficiently broad beam () that justifies the use
of the standard stationary 1-D approximation in the electron hydrodynamic
equations, since the pulse width is sufficiently bigger than the pulse length
(). Furthermore, with the laser power of TW
and the spot size, the dimensionless laser vector potential
is sufficiently small , the nonlinearity is sufficiently weak to allow the power
expansion in the nonlinear Poissons's equation. Such approximation yields a
nonlinear Schr\" odinger equation with a reactive nonlocal nonlinear term. The
nonlocality contains a cosine function under the integral, indicating the
oscillating wake. For a smaller spot size that is used for the Thomson
scattering, m, the length and the width of the pulse are
comparable, and it is not possible to use the 1-D approximation in the
hydrodynamic equations. With such small spot size, the laser intensity is very
large, and most likely some sort of chanelling in the plasma would take place
(the plasma gets locally depleted so much that the electromagnetic wave
practically propagates in vacuum).Comment: Oral contribution O3.205 delivered at the 38th EPS Conference on
Plasma Physics, Strasbourg, France, 26 June - 1 July, 201
The thermal-wave model: A Schroedinger-like equation for charged particle beam dynamics
We review some results on longitudinal beam dynamics obtained in the framework of the Thermal Wave Model (TWM). In this model, which has recently shown the capability to describe both longitudinal and transverse dynamics of charged particle beams, the beam dynamics is ruled by Schroedinger-like equations for the beam wave functions, whose squared modulus is proportional to the beam density profile. Remarkably, the role of the Planck constant is played by a diffractive constant epsilon, the emittance, which has a thermal nature
Self consistent thermal wave model description of the transverse dynamics for relativistic charged particle beams in magnetoactive plasmas
Thermal Wave Model is used to study the strong self-consistent Plasma Wake
Field interaction (transverse effects) between a strongly magnetized plasma and
a relativistic electron/positron beam travelling along the external magnetic
field, in the long beam limit, in terms of a nonlocal NLS equation and the
virial equation. In the linear regime, vortices predicted in terms of
Laguerre-Gauss beams characterized by non-zero orbital angular momentum (vortex
charge). In the nonlinear regime, criteria for collapse and stable oscillations
is established and the thin plasma lens mechanism is investigated, for beam
size much greater than the plasma wavelength. The beam squeezing and the
self-pinching equilibrium is predicted, for beam size much smaller than the
plasma wavelength, taking the aberrationless solution of the nonlocal Nonlinear
Schroeding equation.Comment: Poster presentation P5.006 at the 38th EPS Conference on Plasma
Physics, Strasbourg, France, 26 June - 1 July, 201
Soliton solutions of 3D Gross-Pitaevskii equation by a potential control method
We present a class of three-dimensional solitary waves solutions of the
Gross-Pitaevskii (GP) equation, which governs the dynamics of Bose-Einstein
condensates (BECs). By imposing an external controlling potential, a desired
time-dependent shape of the localized BEC excitation is obtained. The stability
of some obtained localized solutions is checked by solving the time-dependent
GP equation numerically with analytic solutions as initial conditions. The
analytic solutions can be used to design external potentials to control the
localized BECs in experiment.Comment: 11 pages, 5 figures, submitted to Phys. Rev.
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