Showing papers on "Relativistic plasma published in 2021"

Spatio-temporal characterization of attosecond pulses from plasma mirrors.

Abstract: Reaching light intensities above 1025 W cm−2 and up to the Schwinger limit of order 1029 W cm−2 would enable the testing of fundamental predictions of quantum electrodynamics. A promising—yet challenging—approach to achieve such extreme fields consists in reflecting a high-power femtosecond laser pulse off a curved relativistic mirror. This enhances the intensity of the reflected beam by simultaneously compressing it in time down to the attosecond range, and focusing it to submicrometre focal spots. Here we show that such curved relativistic mirrors can be produced when an ultra-intense laser pulse ionizes a solid target and creates a dense plasma that specularly reflects the incident light. This is evidenced by measuring the temporal and spatial effects induced on the reflected beam by this so-called plasma mirror. The all-optical measurement technique demonstrated here will be instrumental for the use of relativistic plasma mirrors with the upcoming generation of petawatt lasers that recently reached intensities of 5 × 1022 W cm−2, and therefore constitutes a viable experimental path to the Schwinger limit. Relativistic mirrors are a promising tool to reach laser intensities up to the Schwinger limit. Such a mirror is created in ultra-intense laser–solid interactions, and its temporal and spatial effects on the reflected laser beam are characterized.

Probing Strong-Field QED with Doppler-Boosted Petawatt-Class Lasers.

Abstract: We propose a scheme to explore regimes of strong-field quantum electrodynamics (SF QED) otherwise unattainable with the currently available laser technology. The scheme relies on relativistic plasma mirrors curved by radiation pressure to boost the intensity of petawatt-class laser pulses by Doppler effect and focus them to extreme field intensities. We show that very clear SF QED signatures could be observed by placing a secondary target where the boosted beam is focused.

Reflecting petawatt lasers off relativistic plasma mirrors: a realistic path to the Schwinger limit

Abstract: The quantum vacuum plays a central role in physics. Quantum electrodynamics (QED) predicts that the properties of the fermionic quantum vacuum can be probed by extremely large electromagnetic fields. The typical field amplitudes required correspond to the onset of the ‘optical breakdown’ of this vacuum, expected at light intensities >4.7×1029 W/cm2. Approaching this ‘Schwinger limit’ would enable testing of major but still unverified predictions of QED. Yet, the Schwinger limit is seven orders of magnitude above the present record in light intensity achieved by high-power lasers. To close this considerable gap, a promising paradigm consists of reflecting these laser beams off a mirror in relativistic motion, to induce a Doppler effect that compresses the light pulse in time down to the attosecond range and converts it to shorter wavelengths, which can then be focused much more tightly than the initial laser light. However, this faces a major experimental hurdle: how to generate such relativistic mirrors? In this article, we explain how this challenge could nowadays be tackled by using so-called ‘relativistic plasma mirrors’. We argue that approaching the Schwinger limit in the coming years by applying this scheme to the latest generation of petawatt-class lasers is a challenging but realistic objective.

Particle Energization in Relativistic Plasma Turbulence: Solenoidal versus Compressive Driving

Abstract: Many high-energy astrophysical systems contain magnetized collisionless plasmas with relativistic particles, in which turbulence can be driven by an arbitrary mixture of solenoidal and compressive motions. For example, turbulence in hot accretion flows may be driven solenoidally by the magnetorotational instability or compressively by spiral shock waves. It is important to understand the role of the driving mechanism on kinetic turbulence and the associated particle energization. In this work, we compare particle-in-cell simulations of solenoidally driven turbulence with similar simulations of compressively driven turbulence. We focus on plasma that has an initial beta of unity, relativistically hot electrons, and varying ion temperature. Apart from strong large-scale density fluctuations in the compressive case, the turbulence statistics are similar for both drives, and the bulk plasma is described reasonably well by an isothermal equation of state. We find that nonthermal particle acceleration is more efficient when turbulence is driven compressively. In the case of relativistically hot ions, both driving mechanisms ultimately lead to similar power-law particle energy distributions, but over a different duration. In the case of non-relativistic ions, there is significant nonthermal particle acceleration only for compressive driving. Additionally, we find that the electron-to-ion heating ratio is less than unity for both drives, but takes a smaller value for compressive driving. We demonstrate that this additional ion energization is associated with the collisionless damping of large-scale compressive modes via perpendicular electric fields.

Ray-tracing in relativistic jet simulations: A polarimetric study of magnetic field morphology and electron scaling relations

Abstract: The jets emanating from the centers of active galactic nuclei (AGN) are among the most energetic objects in the universe. Investigating how the morphology of the jet's synchrotron emission depends on the magnetic nature of the jet's relativistic plasma is fundamental to the comparison between numerical simulations and the observed polarization of relativistic jets. Through the use of 3D relativistic magnetohydrodynamic (RMHD) jet simulations (computed using the PLUTO code) we study how the jet's synchrotron emission depends upon the morphology of the jet's magnetic field structure. Through the application of polarized radiative transfer and ray-tracing (via the RADMC-3D code) we create synthetic radio maps of the jet's total intensity as well as the linearly and circularly polarized intensity for each jet simulation. In particular, we create synthetic ray-traced images of the jet's polarized synchrotron emission when the jet carries a predominantly poloidal, helical, and toroidal magnetic field. We also explore several scaling relations in which the underlying electron power-law distribution is set proportional to: (i) the jet's thermal plasma density, (ii) the jet's internal energy density, and (iii) the jet's magnetic energy density. We find that: (i) the jet emission is edge brightened when the magnetic field is toroidal in nature and spine brightened when the magnetic field is poloidal in nature, (ii) the circularly polarized emission exhibits both negative and positive signs for the toroidal magnetic field morphology at an inclination of 45° as well as 5°, and (iii) the relativistic jet's emission is largely independent of different emission scaling relations when the ambient medium is excluded.

Modeling general-relativistic plasmas with collisionless moments and dissipative two-fluid magnetohydrodynamics

Abstract: Relativistic plasmas are central to the study of black hole accretion, jet physics, neutron star mergers, and compact object magnetospheres. Despite the need to accurately capture the dynamics of these plasmas and the implications for relativistic transients, their fluid modeling is typically done using a number of (overly) simplifying assumptions, which do not hold in general. This is especially true when the mean free path in the plasma is large compared to the system size, and kinetic effects start to become important. Going beyond common approaches used in the literature, we describe a fully relativistic covariant 14-moment based two-fluid system appropriate for the study of electron-ion or electron-positron plasmas. This generalized Israel-Stewart-like system of equations of motion is obtained directly from the relativistic Boltzmann-Vlasov equation. Crucially, this new formulation can account for non-ideal effects, such as anisotropic pressures and heat fluxes. We show that a relativistic two-fluid plasma can be recast as a single fluid coupled to electromagnetic fields with (potentially large) out-of-equilibrium corrections. In particular, we keep all electron degrees of freedom, which provide self-consistent evolution equations for electron temperature and momentum. The equations outlined in this paper are able to capture the full two-fluid character of collisionless plasmas found in black hole accretion and flaring processes around compact objects, as well Braginskii-like two-fluid magnetohydrodynamics applicable to weakly collisional plasmas inside accretion disks. This new formulation will be instrumental in the construction of a large class of next-generation simulations of relativistic transient phenomena produced around black holes and neutron stars.

Plasmon Excitations in Partially Screened Two-Dimensional Electron Systems (Brief Review)

Abstract: The latest achievements in the study of the physical properties of plasmon excitations in partially screened two-dimensional electron systems based on AlGaAs/GaAs heterostructures have been reviewed. It has been revealed that a proximity plasmon, i.e., a specific type of two-dimensional plasma waves, is excited in such systems. It has been established experimentally that these plasma waves have a number of new physical properties. First, the dispersion relation of partially screened plasmons combines features of both screened and unscreened two-dimensional plasmons. Second, an edge branch is absent in the magnetic dispersion relation of the revealed proximity mode. Finally, a “charged” relativistic plasma mode with a number of unique properties is excited in the system if the gate is connected to the two-dimensional system through an external circuit. The reported new results expand the horizon of possible applications of plasmonics in the field of microwave and terahertz electronics.

Intense high-order harmonic vector beams from relativistic plasma mirrors

Abstract: Vector beams, with a spatial nonuniform polarization distribution, are important for many applications due to their unique field characteristics and novel effects when interacting with matter. Here, through three-dimensional particle-in-cell simulations, we demonstrate that intense vector beams in the extreme-ultraviolet to x-ray spectral region can be generated by means of high harmonic generation (HHG) in the relativistic regime. The vector features of the fundamental laser beam can be transferred to the higher frequency emission coherently during the extreme nonlinear HHG dynamics from relativistic plasma mirrors. The vector harmonic beams can be synthesized into attosecond vector beams. It is also possible to generate vector harmonic beams carrying orbital angular momentum. Such bright vortices and vector light sources present new opportunities in various applications such as imaging with high spatial and temporal resolution, ultrafast magnetic spectroscopy, and particle manipulation.

Turbulence and particle acceleration in a relativistic plasma

Abstract: In a collisionless plasma, the energy distribution function of plasma particles can be strongly affected by turbulence, in particular, it can develop a non-thermal power-law tail at large energies. We argue that turbulence with initially relativistically strong magnetic perturbations (magnetization parameter $\sigma \gg 1$) quickly evolves into a state with ultra-relativistic plasma temperature but mildly relativistic turbulent fluctuations. We present a phenomenological and numerical study suggesting that in this case, the exponent $\alpha$ in the power-law particle energy distribution function, $f(\gamma)d\gamma\propto \gamma^{-\alpha}d\gamma$, depends on magnetic compressibility of turbulence. Our analytic prediction for the scaling exponent $\alpha$ is in good agreement with the numerical results.

Self-Trapping of Extreme Light

Abstract: We use the qualitative, simplified modeling, and approximately self-consistent nonlinear-optical approaches to explain the nature of the regime under which relativistically intense laser pulses propagate in a plasma to distances exceeding the Rayleigh length considerably, as was found earlier by numerical simulation. Such a regime requires certain matching of the size of the laser spot with the plasma density and the laser pulse intensity. It corresponds to the so-called self-trapping of radiation, which has been well known since the 1960s for the quadratic nonlinearity of the medium’s dielectric permittivity and, as has been established, takes place for the relativistic plasma nonlinearity as well. The case of the plasma with a near-critical density is considered as it is of greatest interest in the context of practical applications. Synchronization of chaotic motions of the electrons accelerated by the laser pulse in the self-trapping regime is discussed.

Relativistic plasma aperture for laser intensity enhancement

Abstract: A substantial increase in local laser intensity is observed in the near field behind a plasma shutter. This increase is caused by the interference of the diffracted light at the relativistic plasma aperture and it is studied both analytically and using numerical simulations. This effect is only accessible in the regime of relativistically induced transparency and thus it requires a careful choice of laser and target parameters. The theoretical estimates for the maximum field strength and its spatial location as a function of target and laser parameters are provided and compared with simulation results. Our full 3D particle-in-cell simulations indicate that the laser intensity may be increased roughly by an order of magnitude, improving the feasibility of strong field QED research with the present generation of lasers.

Generalized entropy production in collisionless plasma flows and turbulence

Abstract: Collisionless plasmas exhibit nonthermal and anisotropic particle distributions after being energized; as a consequence, they enter a low-entropy state relative to the thermal state. The Vlasov equations predict that in a collisionless plasma with closed boundaries, entropy is formally conserved, along with an infinite set of other Casimir invariants; this provides a seemingly strong constraint that may explain how plasmas maintain low entropy. Nevertheless, entropy is commonly believed to be produced due to phase mixing or nonlinear entropy cascades. The question of whether such anomalous entropy production occurs, and of how to characterize it quantitatively, is a fundamental problem in plasma physics. We construct a new theoretical framework for characterizing entropy production (in a generalized sense) based on a set of ideally conserved "Casimir momenta" derived from the Casimir invariants. The growth of the Casimir momenta relative to the average particle momentum indicates entropy production. We apply this framework to quantify entropy production in particle-in-cell simulations of laminar flows and turbulent flows driven in relativistic plasma, where efficient nonthermal particle acceleration is enabled. We demonstrate that a large amount of anomalous entropy is produced by turbulence despite nonthermal features. The Casimir momenta grow to cover a range of energies in the nonthermal tail of the distribution, and we correlate their growth with spatial structures. These results have implications for reduced modeling of nonthermal particle acceleration and for diagnosing irreversible dissipation in collisionless plasmas such as the solar wind and Earth's magnetosphere.

Sub-laser-cycle control of relativistic plasma mirrors

Abstract: We present measurements of high-order harmonics and relativistic electrons emitted into the vacuum from a plasma mirror driven by temporally-shaped ultra-intense laser waveforms, produced by collinearly combining the main laser field with its second harmonic. We experimentally show how these observables are influenced by the phase delay between these two frequencies at the attosecond timescale, and relate these observations to the underlying physics through an advanced analysis of 1D/2D Particle-In-Cell simulations. These results demonstrate that sub-cycle shaping of the driving laser field provides fine control on the properties of the relativistic electron bunches responsible for harmonic and particle emission from plasma mirrors.

Emissions of brilliant attosecond pulse in circular polarization by using inclined lasers

Abstract: We propose a practical approach to produce intense circularly polarized (CP) attosecond pulses using inclined linearly polarized (LP) lasers from relativistic plasma mirrors. Due to the dynamics of the plasma surface currents at the radiation point, the phase difference of high-order harmonics in the two orthogonal transverse directions approaches π/2 by proper inclination angle and incident angle of the driving laser. One- and three-dimensional particle-in-cell simulations show that CP attosecond extreme-ultraviolet pulses with an intensity about 3.1×1020 W/cm2 are obtained by using a LP laser with an intensity of 1.3×1021 W/cm2, both the inclination and incident angles of which are 45°. This approach is more feasible than previous approaches using CP/two-color driving lasers, and such a CP attosecond source provides a unique tool for a variety of chirality-sensitive applications.

Particle energization in relativistic plasma turbulence: solenoidal versus compressive driving

Abstract: Many high-energy astrophysical systems contain magnetized collisionless plasmas with relativistic particles, in which turbulence can be driven by an arbitrary mixture of solenoidal and compressive motions. For example, turbulence in hot accretion flows may be driven solenoidally by the magnetorotational instability or compressively by spiral shock waves. It is important to understand the role of the driving mechanism on kinetic turbulence and the associated particle energization. In this work, we compare particle-in-cell simulations of solenoidally driven turbulence with similar simulations of compressively driven turbulence. We focus on plasma that has an initial beta of unity, relativistically hot electrons, and varying ion temperature. Apart from strong large-scale density fluctuations in the compressive case, the turbulence statistics are similar for both drives, and the bulk plasma is described reasonably well by an isothermal equation of state. We find that nonthermal particle acceleration is more efficient when turbulence is driven compressively. In the case of relativistically hot ions, both driving mechanisms ultimately lead to similar power-law particle energy distributions, but over a different duration. In the case of non-relativistic ions, there is significant nonthermal particle acceleration only for compressive driving. Additionally, we find that the electron-to-ion heating ratio is less than unity for both drives, but takes a smaller value for compressive driving. We demonstrate that this additional ion energization is associated with the collisionless damping of large-scale compressive modes via perpendicular electric fields.

Contrast enhancement of ultra-intense laser pulses by relativistic plasma shutter

Abstract: An increasing intensity of the laser systems becomes available for experiments in the fields of particle acceleration, radiation sources and many other applications. The higher intensity of the laser irradiation is inherently accompanied by the growth of the amplified spontaneous emission (ASE) pedestal and other parasitic effects. Considering the forthcoming generation of multi-PW laser systems, the nanosecond and picosecond pedestals significantly exceed the respective plasma formation thresholds and may have detrimental effects on the laser--target interaction. One of the promising methods to mitigate these effects is the relativistic plasma shutter, where an ultra-thin foil is placed in front of the target. The initial interaction with the shutter increases the temporal contrast, where the pre-plasma is opaque for the pedestal, but relativistically transparent for the main pulse. Moreover, the created pre-plasma exhibits a focussing effect, increasing the effective intensity of the main pulse. Two-dimensional hydrodynamic simulations of the pedestal are performed, followed by PIC simulations of the main pulse. The parameters of the shutter, like density and thickness, are varied to optimize performance of the configuration.

Production and Persistence of Extreme Two-temperature Plasmas in Radiative Relativistic Turbulence

Abstract: Turbulence is a predominant process for energizing electrons and ions in collisionless astrophysical plasmas, and thus is responsible for shaping their radiative signatures (luminosity, spectra, and variability). To better understand the kinetic properties of a collisionless radiative plasma subject to externally driven turbulence, we investigate particle-in-cell simulations of relativistic plasma turbulence with external inverse Compton cooling acting on the electrons. We find that ions continuously heat up while electrons gradually cool down (due to the net effect of radiation), and hence the ion-to-electron temperature ratio T i /T e grows in time. We show that T i /T e is limited only by the size and duration of the simulations (reaching ), indicating that there are no efficient collisionless mechanisms of electron–ion thermal coupling. This result has implications for models of radiatively inefficient accretion flows, such as observed in the Galactic center and in M87, for which so-called two-temperature plasmas with have been invoked to explain their low luminosity. Additionally, we find that electrons acquire a quasi-thermal distribution (dictated by the competition of turbulent particle energization and radiative cooling), while ions undergo efficient nonthermal acceleration (acquiring a harder distribution than in equivalent nonradiative simulations). There is a modest nonthermal population of high-energy electrons that are beamed intermittently in space, time, and direction; these beamed electrons may explain rapid flares in certain high-energy astrophysical systems (e.g., in the Galactic center). These numerical results demonstrate that extreme two-temperature plasmas can be produced and maintained by relativistic radiative turbulence.

Generation of quasi-monoenergetic proton beams via quantum radiative compression

Abstract: Dense high-energy monoenergetic proton beams are vital for wide applications, thus modern laser-plasma-based ion acceleration methods are aiming to obtain high-energy proton beams with energy spread as low as possible. In this work, we put forward a quantum radiative compression method to post-compress a highly accelerated proton beam and convert it to a dense quasi-monoenergetic one. We find that when the relativistic plasma produced by radiation pressure acceleration collides head-on with an ultraintense laser beam, large-amplitude plasma oscillations are excited due to quantum radiation-reaction and the ponderomotive force, which induce compression of the phase space of protons located in its acceleration phase with negative gradient. Our three-dimensional spin-resolved QED particle-in-cell simulations show that hollow-structure proton beams with a peak energy $\sim$ GeV, relative energy spread of few percents and number $N_p\sim10^{10}$ (or $N_p\sim 10^9$ with a $1\%$ energy spread) can be produced in near future laser facilities, which may fulfill the requirements of important applications, such as, for radiography of ultra-thick dense materials, or as injectors of hadron colliders.

Study of small perturbations of a stationary state in a model of upper hybrid plasma oscillations

Abstract: It is shown that a constant external magnetic field, generally speaking, is not able to prevent breaking (loss of smoothness) of relativistic plasma oscillations, even if they are arbitrarily small perturbations of the zero steady-state. This result sharply differs from the non-relativistic case, for which it is possible to suppress the breaking of oscillations at any initial deviations by increasing the intensity of the magnetic field \cite {RCharx}. Nevertheless, even in the relativistic case, there are subclasses of solutions corresponding to solutions that are globally smooth in time.

Reflectivity and spectrum of relativistic flying plasma mirrors

Abstract: Flying plasma mirrors induced by intense lasers via laser wake field acceleration scheme have been proposed as a promising way to generate few-cycle EUV or x-ray lasers. In addition, if such a relativistic plasma mirror can accelerate, then it would serve as an analog black hole to investigate the information loss paradox associated with the black hole Hawking evaporation. Among these applications, the reflectivity, which is usually frequency-dependent, would affect the outgoing photon spectrum and, therefore, impact on the analysis of the physics under investigation. In this paper, these two issues are investigated analytically and numerically with one-dimensional particle-in-cell simulations. Based on our simulation results, we propose a new model that provides a better estimate of the reflectivity than those studied previously. Moreover, we found that the peak frequency of the reflected spectrum of a Gaussian incident wave deviates from the expected value, 4γ2ω, due to the dependence of reflectivity on the frequency of the incident wave.

Pitch Angle Anisotropy Controls Particle Acceleration and Cooling in Radiative Relativistic Plasma Turbulence

Abstract: Nature's most powerful high-energy sources are capable of accelerating particles to high energy and radiate it away on extremely short timescales, even shorter than the light crossing time of the system. It is yet unclear what physical processes can produce such an efficient acceleration, despite the copious radiative losses. By means of radiative particle-in-cell simulations, we show that magnetically dominated turbulence in pair plasmas subject to strong synchrotron cooling generates a nonthermal particle spectrum with a hard power-law range (slope $p \sim 1$) within a few eddy turnover times. Low pitch-angle particles can significantly exceed the nominal radiation-reaction limit, before abruptly cooling down. The particle spectrum becomes even harder ($p < 1$) over time owing to particle cooling with an energy-dependent pitch-angle anisotropy. The resulting synchrotron spectrum is hard ($ u F_ u \propto u^s$ with $s \sim 1$). Our findings have important implications for understanding the nonthermal emission from high-energy astrophysical sources, most notably the prompt phase of gamma-ray bursts and gamma-ray flares from the Crab nebula.

From electrons to Janskys: Full stokes polarized radiative transfer in 3D relativistic particle-in-cell jet simulations

Abstract: Context. Despite decades of dedicated observation and study, the underlying plasma composition of relativistic extragalactic jets remains largely unknown.Aims. Relativistic magnetohydrodynamic (RMHD) models are able to reproduce many of the observed macroscopic features of these outflows (e.g., recollimation shocks, jet sheaths and spines, bow shocks, and enshrouding jet cocoons). The nonthermal synchrotron emission detected by very long baseline interferometric arrays, however, is a by-product of the kinetic-scale physics occurring within the jet, physics that is not modeled directly in most RMHD codes. This paper attempts to discern the radiative differences between distinct plasma compositions within relativistic jets using small-scale 3D relativistic particle-in-cell (PIC) simulations.Methods. We made use of a polarized radiative transfer scheme to generate full Stokes imaging of two PIC jet simulations, one in which the jet is composed of an electron-proton (e − − p + ) plasma (i.e., a normal plasma jet), and the other in which the jet is composed of an electron-positron (e − − e + ) plasma (i.e., a pair plasma jet). We examined the differences in the morphology and intensity of the linear polarization and circular polarization (CP) emanating from these two jet simulations.Results. Our PIC simulations, when scaled into physical units, are ∼150 cubic kilometers in size. We find that the fractional level of CP (measured relative to integrated total intensity) emanating from the e − − p + plasma jet is orders of magnitude larger than the level emanating from an e − − e + plasma jet of a similar speed and magnetic field strength. In addition, we find that the morphology of both the linearly and circularly polarized synchrotron emission is distinct between the two jet compositions. These results highlight the following: (i) the potential of high-resolution full-Stokes polarimetric imaging to discern between normal plasma and pair plasma jet emission in larger scale systems and (ii) the challenges faced by kinetic simulations in modeling this emission self-consistently. We also demonstrate the importance of slow-light interpolation and we highlight the effect that a finite light-crossing time has on the resultant polarization when ray-tracing through relativistic plasma. Placing a firm constraint on the plasma content of relativistic extragalactic jets will help to advance our understanding of jet feedback.

Electromagnetic Albedo of Quantum Black Holes

Abstract: We compute the albedo (or reflectivity) of electromagnetic waves off the electron-positron Hawking plasma that surrounds the horizon of a Quantum Black Hole. We adopt the "modified firewall conjecture" for fuzzballs [arXiv:hep-th/0502050,arXiv:1711.01617], where we consider significant electromagnetic interaction around the horizon. While prior work has treated this problem as an electron-photon scattering process, we find that the incoming quanta interact collectively with the fermionic excitations of the Hawking plasma at low energies. We derive this via two different methods: one using relativistic plasma dispersion relation, and another using the one-loop correction to photon propagator. Both methods find that the reflectivity of long wavelength photons off the Hawking plasma is significant, contrary to previous claims. This leads to the enhancement of the electromagnetic albedo for frequencies comparable to the Hawking temperature of black hole horizons in vacuum. We comment on possible observable consequences of this effect.

Photon polarization tensor in a magnetized plasma: absorptive part

Abstract: We calculate the absorptive part of the photon polarization tensor in a hot magnetized relativistic plasma. In the derivation, we utilize a Landau-level representation for the fermion Green's function in a mixed coordinate-momentum space and obtain a closed-form expression for the one-loop polarization tensor. At the leading order in the coupling, its absorptive part is determined by particle and antiparticle splitting processes ($e^{-} \leftrightarrow e^{-}+\gamma$ and $e^{+} \leftrightarrow e^{+}+\gamma $, respectively), as well as by particle-antiparticle annihilation processes ($e^{-} + e^{+}\leftrightarrow \gamma$). The interpretation in terms of quantum transitions between Landau levels is also given. By making use of the photon polarization tensor, we study the differential photon emission rate in the quantum limit of magnetized relativistic plasma. At low energies, the photon emission has a prolate profile with the symmetry axis along the line of the magnetic field. At high energies, on the other hand, the photon emission has an oblate profile. The underlying reasons for such emission profiles are given in both regimes. The general result for the photon polarization tensor is also used to calculate the longitudinal and transverse components of magneto-optical conductivity.

Sub-Cycle Control of Relativistic Plasma Mirror Dynamics

Abstract: We report on carrier-envelope phase (CEP) effects on the emission of high-order harmonics and electron beams from plasma mirrors driven by relativistic-intensity near-single-cycle laser pulses at 1 kHz repetition rate.