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This work considers quantum electron states in the field of twisted waves in a plasma. We consider electromagnetic and electrostatic waves. They can be associated with intense laser pulses carrying orbital angular momentum, and to the resulting twisted wakefields. Klein-Gordon and Dirac equations are considered. We show that twisted Volkov states of electrons in electromagnetic and electrostatic waves in a plasma can be excited, and discuss their main properties. These results support the idea that acceleration of helical electron beams in plasmas is possible.

Summarization: Neutron time of flight signals have been observed with a high resolution neutron spectrometer using the petawatt arm of the Vulcan laser facility at Rutherford Appleton Laboratory from plastic sandwich targets containing a deuterated layer. The neutron spectra have two elements: a high-energy component generated by beam-fusion reactions and a thermal component around 2.45 MeV. The ion temperatures calculated from the neutron signal width clearly demonstrate a dependence on the front layer thickness and are significantly higher than electron temperatures measured under similar conditions. The ion heating process is intensity dependent and is not observed with laser intensities on target below 1020 W cm−2. The measurements are consistent with an ion instability driven by electron perturbations. Presented on: Plasma Physics and Controlled Fusion

There is considerable interest in the propagation dynamics of intense neutrino beams in a background dispersive medium such as dense plasmas, particularly in the search for a mechanism to explain the dynamics of type II supernovae. Neutrino interactions with matter are usually considered as single particle interactions. All the single particle mechanisms describing the dynamical properties of neutrinos in matter are analogous with the processes involving single electron interactions with a medium such as Compton scattering, Cerenkov radiation, etc. However, it is well known that beams of electrons moving through a plasma give rise to a new class of processes known as collective interactions, such as two stream instabilities, which result in either the absorption or generation of plasma waves. Employing the relativistic kinetic equations for neutrinos interacting with dense plasmas via the weak force, we explore collective plasma streaming instabilities driven by neutrino beams. We examine the anomalous transfer between neutrinos and dense plasma via excitation of electron plasma waves. The nonlinear coupling between an intense neutrino beam and a plasma reveals the presence of two regimes, a hydrodynamic regime and a kinetic regime. The latter is responsible for Landau damping or growth of electron plasma waves. In dense fusion stellar plasmas neutrino Landau damping can play a significant role as an additional stellar plasma cooling process. Another interesting result is an asymmetry in the momentum balance imported by the neutrinos to the core of the exploding star due to symmetry breaking by the collapsed star's magnetic fields. This results in a directed velocity of the resulting neutron star or pulsar, explaining the so called 'birth' velocity.

A multi-terawatt, ultra-short laser pulse was used to create a large, well-defined relativistic ionization front, and the collision of a probe laser pulse with it was studied. Due to the good definition of the ionization front it was also possible to isolate the probe frequency up-shift due to the collision, unlike in previous experiments. A good agreement with the theoretical model for photon acceleration was found. Furthermore, we report novel measurements of ionization front velocities, based on the photon acceleration effect, in excess of 0.99c.

Studies of charged-particle acceleration processes remain one of the most important areas of research in laboratory, space and astrophysical plasmas. In this paper, we present the underlying physics and the present status of high gradient and high energy plasma accelerators. We will focus on the acceleration of charged particles to relativistic energies by plasma waves that are created by intense laser and particle beams. The generation of relativistic plasma waves by intense lasers or electron beams in plasmas is important in the quest for producing ultra-high acceleration gradients for accelerators. With the development of compact short pulse high brightness lasers and electron positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high acceleration gradients. These include the plasma beat wave accelerator mechanism, which uses conventional long pulse (~100 ps) modest intensity lasers (I ~ 1014–1016 W cm−2), the laser wakefield accelerator (LWFA), which uses the new breed of compact high brightness lasers ( 1018 W cm−2, the self-modulated LWFA concept, which combines elements of stimulated Raman forward scattering, and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches. In the ultra-high intensity regime, laser/particle beam–plasma interactions are highly nonlinear and relativistic, leading to new phenomena such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm−1 have been generated with particles being accelerated to 200 MeV over a distance of millimetre. Plasma wakefields driven by positron beams at the Stanford Linear Accelerator Center facility have accelerated the tail of the positron beam. In the near future, laser plasma accelerators will be producing GeV particles.

Emission of twisted photons, carrying orbital angular momentum, from QED vacuum is considered. This is a new type of radiation which can be excited by a Gaussian laser pulse propagating along the axis of a magnetic wiggler. We consider quantum vacuum as described by the Heisenberg-Euler Lagrangian, and assume propagation of an ultra-intense laser pulse in a static magnetic structure. We show that, in such a configuration, vacuum emission of electromagnetic vortices can occur, at a frequency much larger than that of the intense laser pulse, which can eventually be tuned from the visible up to the XUV range. This new configuration could eventually be useful to reduce classical noise in future experiments.

The nonlinear Debye screening associated with the trapped ion population around a negatively charged dust particle immersed in a plasma is considered here. The analogy between the dressed dust particle in a plasma and an atomic system is explored. It is shown that, in certain limits, the system is described by a Thomas-Fermi–type of wave equation.

The concepts of time refraction and time reflection, which can be built by extending the usual concepts of refraction and reflection into the time domain, are defined and characterized. The corresponding Snell's law and Fresnel's formulae are derived for non-dispersive media.

We consider different processes leading to time symmetry breaking in a Bose–Einstein condensate. Our approach provides a global description of time symmetry breaking, based on the equations of a thermal condensate. This includes quenching and expansion of the condensate, the Kibble–Zurek mechanism associated with the creation of vorticity, the dynamical Casimir effect and the formation of time crystals.

We study twisted wave solutions in a magnetized plasma and provide a wave-kinetic description of an arbitrary spectrum of twisted wave turbulence. We first consider the paraxial equation describing a wave beam propagating along an arbitrary direction with respect to the static magnetic field. We then discuss the properties of the appropriate twisted wave solutions, and establish the corresponding wave-kinetic description of twisted plasma turbulence, valid in quite general conditions. Finally, we consider an example of application, where two twisted modes with different topological charge interact with each other and exchange energy and angular momentum inside the plasma.

We review the production of high-energy protons and neutrons in the interaction of intense lasers with gases, clusters and solid targets. Some potential applications are briefly discussed.

The quantization procedure for low-frequency modes in a plasma has been generalized to include dust-Coulomb waves (DCWs) which are driven by the grain charge oscillations in a dusty plasma. We thus introduce the concept of chargeon, the elementary excitation of the ultra low-frequency electrostatic fields in a dusty plasma, which are mainly supported by the grain charge oscillations. Their characteristic features are similar to the usual phonons, but they correspond to very different physical properties of the medium.

Under violent astrophysical conditions, intense fluxes of neutrinos can drive a novel class of plasma instabilities: the electroweak versions of the standard electron- and photon-driven forward scattering instabilities. Employing the relativistic kinetic equations for the neutrinos interacting with a plasma via the weak interaction force, we explore the different collective plasma instabilities driven by neutrinos. We examine the anomalous energy transfer between the neutrinos and the background plasma via excitation of electron plasma waves (neutrino streaming instability), and the generation of quasi-static B fields (electroweak Weibel instability). The relevance of the electroweak plasma instabilities for the extreme conditions occurring in the lepton era of the early universe, supernovae II, and gamma ray bursters is pointed out. The impact on type II supernovae dynamics is examined, and estimates for the energy deposited via collective mechanisms behind the outgoing shock are presented. We show that electroweak plasma instabilities might play an important role in the re-energization of the stalled shock in SNe II.

The formation of nonlinear structures in a self-gravitating dusty plasma is considered when the dust dynamics includes the electrostatic and gravitational forces on an equal footing. Here, we obtain a Helmholtz wave equation, which describes the propagation of stationary gravitational-electrostatic waves. The characteristic lengths of the space regularities, as found here, are much smaller than the wavelengths of the gravitational-electrostatic waves. Furthermore, it is shown that consideration of a uniform dusty plasma rotation around a fixed axis, gives rise to a circular rotating filament structure. Finally, the problem of the Jeans instability for circular waves in a rotating dusty plasma is generalized, and it is found that the purely growing Jeans instability assumes the form of a periodic instability.

A review of recent work on collective neutrino-plasma interactions is presented. The basic physical concepts of this new field as well as some possible astrophysical problems where the physics of collective neutrino-plasma interactions can have a radical impact, are discussed.

Using a quantum kinetic description, we establish a general expression for the dispersion relation of electron plasma waves in the presence of an arbitrary spectrum of electromagnetic waves. This includes both electron and photon Landau damping. The quantum kinetic description allows us to compare directly these two distinct processes, and to show that they are indeed quite similar. The present work also extends previous results on photon Landau damping onto the quantum domain.

We consider the nonlinear coupling between an exact vortex solution in a Bose–Einstein condensate and a spectrum of elementary excitations in the medium. These excitations, or Bogoliubov–de Gennes modes, are indeed a special kind of phonons. We treat the spectrum of elementary excitations in the medium as a gas of quantum particles, sometimes also called bogolons. An exact kinetic equation for the bogolon gas is derived, and an approximate form of this equation, valid in the quasi-classical limit, is also obtained. We study the energy transfer between the vortex and the bogolon gas, and establish conditions for vortex instability and damping.

We derive a system of two coupled wave-kinetic equations for the condensate and for the thermal gas. This provides a simple and elegant model, based on a two fluid interaction, in the spirit of the traditional theory of superfluidity. One of the fluids is the condensed gas, and the other is the fluid of bogolon quasi-particles. As an illustration, we apply this wave-kinetic model to the description of the second-sound.

We develop a kinetic theory for twisted density waves (phonons), carrying a finite amount of orbital angular momentum, in large magneto optical traps, where the collective processes due to the exchange of scattered photons are considered. Explicit expressions for the dispersion relation and for the kinetic (Landau) damping are derived and contributions from the orbital angular momentum are discussed. We show that for rotating clouds, exhibiting ring-shaped structures, phonons carrying orbital angular momentum can cross the instability threshold and grow out of noise, while the usual plane wave solutions are kinetically damped., 5 pages, 5 figures

Generation of quasi-static magnetic fields, due to the Weibel instability is studied in a relativistic quantum plasma. This instability is induced by a temperature anisotropy. The dispersion relati ...

The concept of photon acceleration is revisited. It is shown here than it can be described as an inelastic scattering process. This new approach is applied to the study of relativistic plasma bubbles or wakefields, as those created by an intense laser pulse or by a particle beam moving in a background plasma. Scattering of an incident probe photon beam by a relativistic plasma density perturbation is considered. The angular dependence of frequency and intensity of the scattered signal are discussed in detail. The case of relativistic electron beams propagating in vacuum is also considered for comparison. Such a scattering process could be used as a diagnostic of the space-time structures created by laser driven bubbles and wakefields, for particle acceleration studies.

A general approach to equilibrium and oscillations in a turbulent Bose–Einstein condensate, valid in the mean-field approximation, is proposed. Two different wave equations, describing the quasi-static equilibrium and the elementary excitations of the medium are derived. In particular, it is shown that a modified Thomas–Fermi equilibrium can be defined in the presence of an arbitrary spectrum of oscillations.The oscillating modes are also determined using Bogoliubov–de Gennes (BdG) equations, valid in different geometrical configurations, such as infinite, cylindrical and toroidal. The case of a non-homogenous density is considered, which includes the modified equilibrium profiles. A general form of dispersion relation for the elementary excitations is derived. Twisted phonons, carrying a finite amount of angular momentum, are shown to be a particular class of BdG modes. They were previously derived from fluid equations. Nonlinear analysis also shows that envelope dark solitons can exist, and correspond to a rarefaction of twisted phonons.

We propose a wave-kinetic description of atmospheric turbulence, where the turbulence spectrum is described as a gas of quasi-particles. We apply this description to the case of zonal structures in the atmosphere, which can be excited by internal gravity wave turbulence. A general expression for the instability growth rates is derived, and the particular example of a nearly mono-kinetic turbulent spectrum is discussed.

We propose a new scheme for observing the phonon analogue of the dynamical Casimir effect (DCE) in a gas of laser-cooled atoms. Namely, the emission of phonon pairs from vacuum can happen due to periodic variations of the effective charge of atoms, caused by a small intensity modulation of laser beams used for cooling and trapping the atoms. Then the ‘temporal Bragg diffraction’ results in phonon backscattering in time, equivalent to the DCE.

We consider elementary excitations in a Bose Einstein condensate, carrying a finite amount of angular momentum. We show that these elementary excitations are modified Bogoliubov oscillations, or phonons with an helical wave structure. These twisted phonon modes can contribute to the total vorticity in a quantum fluid, thus complementing the contribution of the traditional quantum vortices. Linear and nonlinear versions of twisted phonon modes will be discussed. New envelope soliton solutions are shown to exist in a condensate., Comment: 12 pages, no figures

Observations of ion acceleration along auroral field lines at the boundary of the plasma sheet and tail lobe of the Earth show that the energy of the ions increases with decreasing density. The observations can be explained by ion acceleration through Landau resonance with kinetic Alfven waves (KAWs) such that kA·vi = ωA, where kA is the wave vector, vi is the ion resonance velocity and ωA is the Alfven wave frequency. The ion resonance velocities are proportional to the Alfven velocity which increases with decreasing density. This is in agreement with the data if the process is occurring at the plasma sheet tail lobe boundary. A quasi-linear theory of ion acceleration by KAWs is presented. These ions propagate both down towards and away from the Earth. The paths of the Freja and Polar satellites indicate that the acceleration takes place between the two satellites, between 1Re and 5Re. The downward propagating ions develop a horseshoe-type of distribution which has a positive slope in the perpendicular direction. This type of distribution can produce intense lower hybrid wave activity, which is also observed. Finally, the filamentation of shear Alfven waves is considered. It may be responsible for large-scale density striations.

We predict and describe a new collective mode in rotating Bose-Einstein condensates, which is very similar to the Rossby waves in geophysics. In the regime of fast rotation, the Coriolis force dominates the dynamics and acts as a restoring force for acoustic-drift waves along the condensate. We derive a nonlinear equation that includes the effects of both the zero-point pressure and the anharmonicity of the trap. It is shown that such waves have negative phase speed, propagating in the opposite sense of the rotation. We discuss different equilibrium configurations and compare with those resulting from the Thomas-Fermi approximation., Comment: 4 pages, 2 figures (submitted to PRL)

We derive the effective masses for photons in unmagnetized plasma waves using a quantum field theory with two vector fields (gauge fields). In order to properly define the quantum field degrees of freedom we re-derive the classical wave equations on light-front gauge. This is needed because the usual scalar potential of electromagnetism is, in quantum field theory, not a physical degree of freedom that renders negative energy eigenstates. We also consider a background local fluid metric that allows for a covariant treatment of the problem. The different masses for the longitudinal (plasmon) and transverse photons are in our framework due to the local fluid metric. We apply the mechanism of mass generation by gauge symmetry breaking recently proposed by the authors by giving a non-trivial vacuum-expectation-value to the second vector field (gauge field). The Debye length $\lambda_D$ is interpreted as an effective compactification length and we compute an explicit solution for the large gauge transformations that correspond to the specific mass eigenvalues derived here. Using an usual quantum field theory canonical quantization we obtain the usual results in the literature. Although none of these ingredients are new to physicist, as far as the authors are aware it is the first time that such constructions are applied to Plasma Physics. Also we give a physical interpretation (and realization) for the second vector field in terms of the plasma background in terms of known physical phenomena. Addendum: It is given a short proof that equation (10) is wrong, therefore equations (12-17) are meaningless. The remaining results are correct being generic derivations for nonmagnetized plasmas derived in a covariant QFT framework., Comment: v1: 1+6 pages v2: Several discussions rewritten; Abstract rewritten; References added; v3: includes Addendum

We consider the elementary processes associated with time refraction in non-stationary plasmas. We describe the frequency shifts of longitudinal and transverse wave propagation in isotropic plasmas, and their corresponding energy variation, which is a direct consequence of non-stationarity. We also show the appearance of reflected waves, propagating with the same (time-varying) frequency, but in the opposite direction, as a direct consequence of time refraction. The case of an expanding (or contracting) plasma bubble is discussed, and will be applied to an expanding universe, and to sonoluminescence.

We discuss on purely analytical grounds the various mechanisms for electron acceleration, which can be relevant in the Petawatt laser pulse regime. This includes a modified version of the well-known wakefield acceleration (dominant for short pulses), stochastic acceleration due to counter-propagating laser pulses (which could be dominant for long pulses) and the relativistic photon mirror or the snow-plow effect (which could lead to enhanced single step acceleration). We discuss other stochastic processes related to the interaction between direct and wakefield acceleration. Approximate analytical criteria for stochastic and enhanced acceleration regimes are established. Our discussion also includes excitation of unstable betatron oscillations. The present analytical models could be relevant to the interpretation of both simulations and experiments.

Recently, we investigated the interaction between broadband drift mode turbulence and zonal flows near the edge of a region of magnetized plasma (Trines et al 2005 Phys. Rev. Lett. 94 165002). Our simulation results showed the development of a zonal flow through the modulational instability of the drift wave distribution, as well as the existence of solitary zonal flow structures about an ion gyroradius wide, drifting towards steeper relative density gradients. Both the growth rate of the turbulence and the particle/energy transport across the plasma boundary can be stabilized by adjusting the plasma density gradient. This spontaneous formation of solitary wave structures has also been found in Cluster satellite observations (Trines et al 2007 Phys. Rev. Lett. 99 205006), confirming our earlier theoretical predictions. We will discuss the consequences of our results for our understanding of the Earth's magnetopause, as well as for the study of zonal flows in tokamaks.

Nonlinear processes associated with short laser pulse propagation in dielectric crystals are considered. They include photon acceleration of probe high frequency photons interacting with long wavelength polariton fields, and polariton wakefield excitation by short laser pulses. This could be useful to the understanding of tera-Hertz radiation sources.

The interaction of broadband turbulence with monochromatic plasma waves has been studied. A kinetic equation for quasi-particles is used to describe the turbulence. Beam instabilities occur in this interaction when the group velocity of the shortwavelength wave packets, or quasi-particles, is nearly equal to the phase velocity of the long-wavelength monochromatic wave. Depending on the bandwidth of the turbulence, either a kinetic resonant instability, e.g. quasi-particle Landau damping, or a hydrodynamic instability, e.g. a modulational instability, will develop. This establishes a direct link between short- and long-wavelength perturbations of the medium. In this paper, the interaction between broadband drift mode turbulence and nearly monochromatic zonal flows has been studied numerically. Simulations have been conducted in which a particle-in-cell representation is used for the quasi-particles, while a fluid model is employed for the plasma. The interactions have been studied in both a tokamak-like configuration and a pseudo-shockwave configuration. Simulation results show the development of a zonal flow through the modulational instability of the drift wave distribution, as well as the existence of solitary zonal flow structures drifting towards steeper relative density gradients. The coupling between short- and long-wavelength modes found here is distinct from the usual picture of direct and inverse energy cascades, and it can be used as a new paradigm for the fluid and plasma turbulence theories.

We examine the anomalous energy transfer from neutrinos to the background dense plasma via the excitation of electron plasma waves. Relativistic equations including external magnetic fields are presented. Solutions of the dispersion relation describing the nonlinear coupling between a neutrino beam and plasma waves demonstrate the existence of two regimes: (a) the kinetic regime and (b) the hydrodynamical regime. We demonstrate that the hydrodynamical regime has a growth rate many orders of magnitude larger than the kinetic regime. A nonlinear equation describing the coupling of plasma waves is derived from the relativistic kinetic equations where the neutrino pondero-motive force is explicitly written. We show the similarity between a neutrino beam driven plasma wave and an electron beam driven plasma wave, there is also a striking similarity to photon driven plasma wakes.

Starting from the concept of quasi-particle, a general view is proposed on plasma turbulence. A wave kinetic equation is used to describe the broadband turbulence interacting with monochromatic waves. Resonant interactions between the quasi-particles and the large scale plasma perturbations establish a direct and efficient energy link between short and large-scale perturbations in a plasma. This link is distinct from the usual picture of direct and inverse energy cascades, and can be used as a new paradigm for plasma turbulence.

It is found that the growth rate of the ion-temperture-gradient (ITG) mode is enhanced in the presence of negatively charged dust particulates in magnetized plasmas. Furthermore, the nonlinear equations that govern the interaction of finite amplitude ITG modes in impurity containing plasmas admit vortex chains as a possible stationary solution.

The magnetic properties of neutrinos, as a relativistic gas, are described. Thermodynamics of the neutrino gas in a strong magnetic field is considered, including the contribution of the interaction between the magnetic moment of neutrinos and the external magnetic field. The magnetic susceptibility is found for some special cases.

Stimulated scattering of the intense electron-neutrino burst in a background of neutrons is investigated. We derive the linear growth rates for several regimes of interest. It is shown that this process is formally equivalent to the usual Stimulated Brillouin Scattering found in laser coupling to ion acoustic oscillations. The influence of this instability in the neutrinosphere and the consequences for the supernovae dynamics are also discussed.