Self modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

Self modulated dynamics of a relativistic charged particle beam is reviewed within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.Comment: This is a 10 pages manuscript which contain 4 figures. This manuscript is recently submitted in 'Nuclear Instruments and Methods in Physics Research Section A' as a proceeding of the conference 'EAAC 2015

A Strategic Planning Intervention Employing Large Group Change: A Scholar/Practitioner Application

We present a scholar-practitioner collaboration applying a large group positive change project, representing the first such application methodology involving first responders. Positive change intervention is based on a multistage process involving Appreciative Inquiry and S.O.A.R. (Strengths, Opportunities, Aspirations and Results), designed to engage the community in inclusion, transparency, and mutual commitment in developing a strategic plan. Part of this plans objective is acquiring national accreditation, which has only been obtained by 217 of 30,052 fire department in the country. The project included 30 interns and 64 interviews with employees, trustees, and community residents, in preparation for the SOAR strategic planning sessio

The quantum plasma lens concept: a preliminary investigation

Recently, a theoretical investigation of the collective and nonlocal quantum effects has been carried out within the framework of a quantum approach to the relativistic charged particle beam travelling in a cold, collisionless, strongly magnetized plasma. This has been done taking into account both the plasma wake field excitation and the quantum paraxial approximation. On the basis of this theory, here we carry out a preliminary study of the transverse effects experienced by a cold relativistic beam through a thin plasma slab (plasma lens). In the strongly nonlocal regime, in which the beam experiences a very strong focusing effect, the scheme of plasma lens is reviewed in terms of the wave description provided by the above quantum theory

Propagation of ultrastrong femtosecond laser pulses in PLASMON-X

In this work we present the derivation of the nonlinear equations that describe the propagation of ultrashort laser pulses in a plasma, in the PLASMON-X device, using a fully relativistic hydrodynamic description for electrons. It is shown that for the PLASMONX scheme used for the electron acceleration, it is justified to use a 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 $W\leq 300$ TW and the initial $130\,\,\mu{\rm m}$ spot size, the nonlinearity is sufficiently weak to allow for the power expansion in the nonlinear Poissons's equation, yielding a version of the nonlocal nonlinear Schr\"{o}dinger eqiation, with a periodic nonlocality. While in a one-dimensional limit the standard wakefield generation is obtained, our two-dimensional numerical studies, including the full nonlinear response, reveal the transverse collapse (or the self-focussing) of the pulse. Under the typical operating conditions, the self-focussing is sufficiently slow to allow the interaction between the laser pulse and the accelerated electrons along an interaction length (in the laboratory frame) that exceeds 1 m

The psychoanalytic dimension of Adorno's critical theory

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN014728 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Self consistent nonlinear transverse quantum dynamics of a cold relativistic electron beam in a magnetized plasma

A relativistic electron/positron beam travelling in a cold plasma in the overdense regime (n0>> nb) is the driver of large amplitude plasma oscillations that are generated by the Plasma Wake Field excitation. The beam experiences the 3D effects of the wake field that it has produced by itself (self interaction). In the long beam limit, the transverse effects due to the self interaction (f.i., self focusing/defocusing) are dominant compared to the longitudinal ones. Here, ignoring the longitudinal beam dynamics, a theoretical investigation of the quantum transverse beam motion is carried out when a relativistic electron/positron beam is travelling along an external magnetic field. This is done by adopting a fluid model of a magnetized plasma describing the Plasma Wake Field excitation driven by the beam density and current. On the other hand, taking into account the quantum nature of the single particle of the beam, it is shown that the transverse electron/positron dynamics is governed by a 2D Schrödinger equation in the form of the Gross-Pitaevskii equation. The latter accounts for the collective effects due to both the plasma wake field and the external magnetic field. The above set of equations governing the beam-plasma system (i.e., fluid plus 2D Schrödinger quations), is then reduced to a pair of coupled equations that can be thought as a quantum Zakharov system, leading in general to a 2D nonlocal and nonlinear Schrödinger equation. In the weakly focussed regime, the analysis of this equation is carried out, both analytically and numerically. Remarkably, the existence of quantum beam vortices is shown and the conditions for the self focusing and collapse that include the quantum nature of the beam particles are discussed

Nonlocal effects in the self-consistent nonlinear 3D propagation of an ultrastrong, femtosecond laser pulse in plasmas

A theoretical investigation of the interaction of an ultra-strong and ultra-short laser pulse with unmagnetized plasma is carried out and applied to the specifications of the Ti:Sa Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME). The analysis is based on the Lorentz-Maxwell fluid model in the fully relativistic regime taking the pancake approximation. The mathematical model yields Zakharov-like equations, which gives a satisfactory description of a wide range of laser-plasma acceleration configurations. It is shown that the pancake structure is unstable in two dimensions (2D) but the collapse occurs over a distance much longer than the typical active plasma length

Quantum ring soliton formation by strongly nonlocal plasma wake field response to a relativistic electron beam

The relativistic electron/positron particle beam propagation in overdense magnetized plasmas is studied theoretically, using a fluid plasma model and accounting for the quantum properties of individual particles. The collective character of the particle beam manifests through the macroscopic, beam created, plasma wake field. The transverse dynamics is described by the quantum Schr¨odinger equation for the single-particle wave function, within the Hartree mean-field approximation, coupled with the Poisson equations for the wake potential. The resulting nonlinear nonlocal Schr¨odinger equation is solved analytically in the strongly nonlocal regime, yielding breathing/wiggling Hermite-Gauss ring solitons. The nonstationary rings may be parametrically unstable. The conditions for instability and the growth rates are estimated analytically

Quantumlike description of the nonlinear and collective effects on relativistic electron beams in strongly magnetized plasmas

A numerical analysis of the self-interaction induced by a relativistic electron/positron beam in the presence of an intense external longitudinal magnetic field in plasmas is carried out. Within the context of the Plasma Wake Field (PWF) theory in the overdense regime, the transverse beam-plasma dynamics is described by a quantumlike Zakharov system of equations in the long beam limit provided by the Thermal Wave Model (TWM). In the limiting case of beam spot size much larger than the plasma wavelength, the Zakharov system is reduced to a 2D Gross-Pitaevskii-type equation, where the trap potential well is due to the external magnetic field. Vortices, “beam halos” and nonlinear coherent states (2D solitons) are predicted

Self consistent thermal wave model description of the transverse dynamics for relativistic charged particle beams in magnetoactive plasmas

A numerical analysis of the self-interaction induced by a relativistic electron/positron beam in the presence of an intense external longitudinal magnetic field in plasmas is carried out. Within the context of the Plasma Wake Field (PWF) theory in the overdense regime, the transverse beam-plasma dynamics is described by a quantumlike Zakharov system of equations in the long beam limit provided by the Thermal Wave Model (TWM). In the limiting case of beam spot size much larger than the plasma wavelength, the Zakharov system is reduced to a 2D Gross-Pitaevskii-type equation, where the trap potential well is due to the external magnetic field. Vortices, “beam halos” and nonlinear coherent states (2D solitons) are predicted