Nonlinear Compton Scattering Research Articles

Simulation studies of γ-ray radiation in laser-plasma interactions with structured targets

We studied the γ-ray emission from laser interactions with structured targets of Al and Au. Bremsstrahlung and Non-linear Compton Scattering (NCS) emission are considered for the γ-ray emission using the open source 2-D PIC code EPOCH. Different shapes of the target generated additional hot electrons, which helps to enhance the photon energy in individual cases. The enhancement of photon energy is due to the target's shape and the hot electrons. Hot electron generation and their dynamics, like refluxing behavior, are crucial phenomena in thin targets. This study uses four different shapes of Al and Au targets. The relative strength of emissions from both bremsstrahlung and NCS are compared. The shape of the target enhances the γ-ray energy, electron energy, and emitted photon number and improves the electron beam divergence. The effect of each target shape on hot electrons refluxing behavior and the role of the electric and magnetic fields are discussed in detail.

Quantum splitting of electron peaks in ultra-strong fields

Effects of multiple nonlinear Compton scattering on electrons in ultra-strong fields are described using analytic formulas similar to those in the theory of multiple bremsstrahlung. Based on these analytic formulas, a new pure quantum effect of multiple nonlinear Compton scattering called quantum peak splitting is identified: the electron peak splits into two when the average number of nonlinear Compton scatterings per electron passes a threshold of 5.1 and is below 9. Quantum peak splitting stems from the discreteness of quantum radiation reaction, with one of the split peaks being formed by electrons emitting zero to three times and the other by electrons emitting four or more times. This effect provides a new mechanism for the formation of electron peaks, imposes a new beamstrahlung limit on future colliders, and corrects the picture of quantum radiation reaction. Experiments can be performed on lasers with intensities ≳1021 W/cm2, which are reachable on PW-scale facilities.

Applications of Non-linear Inverse Compton Scattering based on the Laser Plasma Accelerators

The generation of energetic photons in the context of inverse Compton scattering has attracted a great lot of interest from many contemporary scientific fields. Radiobiology, materials physics, and medicine are some of the current fields where inverse Compton scattering is used. In this study, the applications of nonlinear inverse Compton scattering will be demonstrated and illustrated based on laser plasma interaction. This paper introduces and highlights the current advancement in this area, which is a crucial component of quantum physics, as well as the potential uses in the future depending on additional study. Thorough explanations are demonstrated and talked about the uses of inverse Compton scattering. To highlight our thoughts on present developments and potential future advancements in the field, we have extended and expanded on the theme using simulations and experimental data. These results pave a path to generate and shed light on guiding further state-of-art proposals for High flux X/gamma ray generation.

Simulation Study of a Bright Attosecond γ-ray Source Generation by Irradiating an Intense Laser on a Cone Target

The interaction between an ultrastrong laser and a cone-like target is an efficient approach to generate high-power radiations such as attosecond pulses and terahertz waves. The objective is to study the γ-ray generation under this configuration with the help of 2D particle-in-cell simulations. It is deciphered that electrons experience three stages, including injection, acceleration and scattering, to emit high-energy photons via nonlinear Compton scattering (NCS). These spatial-separated attosecond γ-ray pulses own high peak brilliance (>1022 photons/(s·mm2·mrad2·0.1%BW)) and high energy (6 MeV) under the case of normalized laser intensity a0=30(I=2×1021 W/cm2). In addition, the cone target turns out to be an order of magnitude more efficient in energy transfer compared to a planar one.

Computational Study of Quantum Coherence from Classical Nonlinear Compton Scattering with Strong Fields

From the covariant formulation of radiation intensity of Hartemann-Kerman model entirely constructed in the classical electrodynamics scenario, a formulation of coherent states has been obtained in an explicit manner represented by the infinite sum of integer-order Bessel functions. Both linear and nonlinear Compton scattering are included, suggesting that Compton processes can be perceived as coherent states of light-matter interaction.

Narrow Bandwidth Gamma Comb from Nonlinear Compton Scattering Using the Polarization Gating Technique.

Nonlinear Compton scattering is a promising source of bright gamma rays. Using readily available intense laser pulses to scatter off the energetic electrons, on the one hand, allows us to significantly increase the total photon yield, but on the other hand, leads to a dramatic spectral broadening of the fundamental emission line as well as its harmonics due to the laser pulse shape induced ponderomotive effects. In this Letter we propose to avoid ponderomotive broadening in harmonics by using the polarization gating technique-a well-known method to construct a laser pulse with temporally varying polarization. We show that by restricting harmonic emission only to the region near the peak of the pulse, where the polarization is linear, it is possible to generate a bright narrow bandwidth comb in the gamma region.

Laser-driven radiation-reaction effect and polarized particle acceleration

<sec>Laser-plasma interaction at intensities beyond 10<sup>22</sup> W/cm<sup>2</sup> enters a new regime where gamma-photon emission and the induced radiation-reaction effect dominate. In extreme laser fields, high energy electrons emit gamma-photons efficiently, which take considerable portion of energy away and impose strong reaction forces on radiating electrons. When the radiation power is comparable to the electron energy gained in a certain period of time, the radiation-reaction (RR) effect becomes significant, which fundamentally changes the picture of laser-plasma interaction. In this review article, we introduce the physics of radiation-reaction force, including both classical description and quantum description. The effects of stochastic emission and particle spins in the quantum-electrodynamics (QED) RR process are discussed. We summarize the RR-induced phenomena in laser-plasma interaction and some proposed measurements of RR. As a supplement, we also introduce the latest progress of producing spin polarized particles based on laser-plasma accelerations, which provides polarized beam sources for verifying the QED-RR effects.</sec><sec>In the classical picture, the RR force can be described by the Landau-Lifshitz (LL) equation, which eliminates the non-physical run-away solution from the Lorentz-Abraham-Dirac (LAD) equation. The damping force could induce the electron trajectories to instantaneously reverse, electrons to cool and even high energy electrons to be reflected by laser pulses. The latter leads to a “potential barrier” at a certain threshold that prevents the electrons of arbitrarily high energy from penetrating the laser field. In general, classical LL equation overestimates the RR effect, thus calling for more accurate quantum description.</sec><sec>When the emitted photon energy is close to the electron energy, radiation becomes discrete. Quantum effects arise such that the process, also known as nonlinear multi-photon Compton Scattering, must be considered in the strong-field QED picture. This is resolved in the Furry picture by using the laser-dressed Volkov state in the local constant cross-field approximation (LCFA). The QED model is applied to particle dynamics via Monte-Carlo (MC) sampling. We introduce the prominent feature of quantum RR-stochastic photon emission. It allows the processes forbidden in classical picture to emerge, such as quantum ‘quenching’, quantum ‘reflection’, etc. These observables validate the strong-field QED theory. Recently, there has been a rising interest in identifying the spin effect in the QED-RR force. We summarize the latest progress of this topic, showing that when spins are coupled with photon emission the electrons of different spin states undergo distinctive RR force. </sec><sec>The RR force has a significant effect on laser-plasma interaction. The review paper introduces recent QED-MC based PIC simulation results. Some key features include electron cooling in laser-driven radiation pressure acceleration and the radiation-reaction trapping (RRT) mechanism. In the RRT regime the laser pulse conveys over 10% of its energy to gamma-photons, facilitating the creation of a highly efficient gamma-ray source and electron-positron pair. In addition, the paper mentions the major efforts to measure the RR effect in recent years. It relies on high energy electrons either colliding with ultra-intense laser pulses or traversing crystals. Primitive observations indicate that existing theories do not match experimental results. Further investigation is required in both SF-QED theory and experiment.</sec><sec>Finally, the review paper discusses the idea of laser-driven polarized particle acceleration as a supplement. The all-optical approach integrates pre-polarized gas target into laser wakefield acceleration, offering a compact all-optical polarized particle source, which is highly favorable for strong-field QED studies, high-energy colliders and material science.</sec>

Generation of Intense Vortex Gamma Rays via Spin-to-Orbital Conversion of Angular Momentum in Relativistic Laser-Plasma Interactions

Vortex $\ensuremath{\gamma}$-ray beams with large orbital angular momentum (OAM) have significant potential applications in material science, nuclear detection, and astrophysics. An all-optical scheme for production of intense vortex $\ensuremath{\gamma}$-ray beams using relativistic laser-plasma interactions is proposed, where the OAM of $\ensuremath{\gamma}$-photons is converted from the spin angular momentum of circularly polarized (CP) lasers. The spin-to-orbital angular momentum conversion is achieved by two processes: resonant acceleration of electrons in CP laser-plasma interactions and nonlinear Compton scattering (NCS) of another linearly polarized laser from the former. Three-dimensional particle-in-cell simulations show that vortex $\ensuremath{\gamma}$-ray beams with a large and controllable OAM of $2.5\ifmmode\times\else\texttimes\fi{}{10}^{18}\ensuremath{\hbar}$ and energy up to hundreds of $\mathrm{MeV}$ can be obtained by using two lasers at intensities of approximately ${10}^{22}\phantom{\rule{0.2em}{0ex}}{\mathrm{W}/\mathrm{cm}}^{2}$, which is much more practical and more efficient than previously proposed NCS of a Laguerre-Gaussian beam.

Quantum Mechanisms of Electron and Positron Acceleration through Nonlinear Compton Scatterings and Nonlinear Breit-Wheeler Processes in Coherent Photon Dominated Regime

Electric force is presently the only means in laboratory to accelerate charged particles to high energies, corresponding acceleration processes are classical and continuous. Here we report on how to accelerate electrons and positrons to high energies using ultra intense lasers (UIL) through two quantum processes, nonlinear Compton scattering and nonlinear Breit-Wheeler process. In the coherent photon dominated regime of these two processes, the former can effectively boost electrons/positrons and the latter can produce high energy electrons and positrons with low energy γ photons. The energy needed for such quantum acceleration (QA) is transferred from large numbers of coherent laser photons through the two quantum processes. QA also collimate the generated high energy electrons and positrons along the laser axis and the effective acceleration distance is of microscopic dimensions. Proof of principle QA experiment can be performed on 100 petawatt (PW) scale lasers which are in building or planning.

Electron Polarimetry with Nonlinear Compton Scattering

Impacts of spin-polarization of an ultrarelativistic electron beam head-on colliding with a strong laser pulse on emitted photon spectra and electron dynamics have been investigated in the quantum radiation regime. We simulate photon emissions quantum mechanically and electron dynamics semiclassically via taking spin-resolved radiation probabilities in the local constant field approximation. A small ellipticity of the laser field brings about an asymmetry in angle-resolved photon spectrum, which sensitively relies on the polarization of the electron beam. The asymmetry is particularly significant in high-energy photon spectra, and is employed for the polarization detection of a high-energy electron beam with extraordinary precision, e.g., better than 0.3\% for a few-GeV electron beam at a density of the scale of $10^{16}$ cm$^{-3}$ with currently available strong laser fields. This method demonstrates for the first time a way of single-shot determination of polarization for ultrarelativistic electron beams via nonlinear Compton scattering. A similar method based on the asymmetry in the electron momentum distribution after the interaction due to spin-dependent radiation reaction is proposed as well.

Higher-Dimensional Caustics in Nonlinear Compton Scattering.

A description of the spectral and angular distributions of Compton scattered light in collisions of intense laser pulses with high-energy electrons is unwieldy and usually requires numerical simulations. However, due to the large number of parameters affecting the spectra such numerical investigations can become computationally expensive. Using methods of catastrophe theory we predict higher-dimensional caustics in the spectra of the Compton scattered light, which are associated with bright narrow-band spectral lines, and in the simplest case can be controlled by the value of the linear chirp of the pulse. These findings require no full-scale calculations and have direct consequences for the photon yield enhancement of future nonlinear Compton scattering x-ray or gamma-ray sources.

Attosecond Gamma-Ray Pulses via Nonlinear Compton Scattering in the Radiation-Dominated Regime.

The feasibility of the generation of bright ultrashort gamma-ray pulses is demonstrated in the interaction of a relativistic electron bunch with a counterpropagating tightly focused superstrong laser beam in the radiation-dominated regime. The Compton scattering spectra of gamma radiation are investigated using a semiclassical description for the electron dynamics in the laser field and a quantum electrodynamical description for the photon emission. We demonstrate the feasibility of ultrashort gamma-ray bursts of hundreds of attoseconds and of dozens of megaelectronvolt photon energies in the near-backwards direction of the initial electron motion. The tightly focused laser field structure and the radiation reaction are shown to be responsible for such short gamma-ray bursts, which are independent of the durations of the electron bunch and of the laser pulse. The results are measurable with the laser technology available in the near future.

Nonlinear double compton scattering in the ultrarelativistic quantum regime.

A detailed analysis of the process of two-photon emission by an electron scattered from a high-intensity laser pulse is presented. The calculations are performed in the framework of strong-field QED and include exactly the presence of the laser field described as a plane wave. We investigate the full nonlinear quantum regime of interaction with a few-cycle pulse, where nonlinear effects in the laser field amplitude, photon recoil, and the short pulse duration substantially alter the emitted photon spectra as compared to those in previously studied regimes. We provide a semiclassical explanation for such differences, based on the possibility of assigning a trajectory to the electron in the laser field before and after each quantum photon emission. Our numerical results indicate the feasibility of investigating experimentally the full ultrarelativistic quantum regime of nonlinear double Compton scattering with available electron accelerator and laser technology.

多光子非线性Compton散射对激光等离子体中强朗缪尔湍动谱的影响

According to the model of multi-photon nonlinear Compton scattering,the influence of the multi-photon nonlinear Compton scattering on the strong Langmuir turbulence spectra in the laser-plasma is studied.A new mechanism of the strong Langmuir turbulence formed by the incident light and scattered optical is given.The revised equation met by the mutual action on the transverse plasma wave,the strong Langmuir turbulence wave and ion acoustic wave and its results of the numerical number modulation are also given.The results show that because the collision frequency between the transverse plasma wave and strong Langmuir turbulence wave is greatly increased by Compton scattering,along the time evolution,the transformation of the energy from the small-k region to the large-k region between the transverse plasma wave and Langmuir wave is faster than that before Compton scattering,and the strenuous collapsing is taken place at the same time.During the anaphase of collapse,the nonlinear effect of the laser-plasma excites out the high degree resonance waves.The energy is diverted from one of the resonance wave to another,and the infinite high degrees resonance wave is formed.The phenomenon on breakage of the wave,the strong Langmuir turbulence controlled by the modulation instability,the stronger laser filamentation and energy egalitarian are taken place.The research results will provide a theoretic support for the further study on the increasing speed mechanism of the strong Langmuir turbulence,abnormal collision and laser heating experimentation and fast igniting experimentation.

Nonlinear Compton Scattering of Laser and High Energy Electron Beams

Nonlinear Compton Scattering of Laser and High Energy Electron Beams

Transition Probability and Polarization of Final Photons in Nonlinear Compton Scattering for Linearly Polarized Laser

The nonlinear Compton scattering of a polarized laser beam is discussed in this paper. Using Volkov's solution and a polarization density matrix, we obtain a complete transition probability formula for a linearly polarized laser and unpolarized electrons. The polarization properties of final photons under different conditions are discussed.

Scaling Law of Nonlinear Compton Scattering

We show that there are two mechanisms responsible for the net energy exchange between an intense pulsed laser and an electron in vacuum, namely, stimulated Compton scattering and nonlinear Compton scattering(NLCS). For NLCS, being the only effect in a mono-frequency continuous laser beam, its contribution is also independently determined. The characteristics of these two mechanisms in connection with the net energy exchange are studied. For the case of a pulsed laser field, it is found that the maximum net energy exchange by NLCS is approximately proportional to Q02(Q0 ≡ eE0/(me ωc)) for Q0 ≳ 100. In addition, the relative importance of these two mechanisms to the net energy exchange at different intensities is explored.

Energy-exchange characteristics in ordinary and nonlinear Compton scattering

Free-electron--photon interaction, if it occurs inside an intense laser field, will be dominated by nonlinear Compton scattering (NLCS), which is quite different from the ordinary Compton scattering. The difference can be, for example, in the number of photons involved in one interaction. In this paper, by both analytical and numerical methods, we will explore in detail their characteristics from the viewpoint of energy exchange in the interaction. Based upon the well-displayed results, we are able to, furthermore, reveal some phenomena underlying NLCS and investigate the corresponding physical implications, such as the threshold effects in NLCS. That is, when ${Q=eE/(m}_{e}\ensuremath{\omega}c)>0.1,$ the low-order NLCS will be depressed while the high orders will be excited. And when Q>10, the high-order NLCS process will become dominant in the electron-photon interaction. As for Q>100, the extra-high-order NLCS will be so strongly excited that the electron dynamics will enter a new regime. Also, we can make use of the obtained results to explain qualitatively the NLCS experiment by Bula et al. [Phys. Rev. Lett. 76, 3116 (1996)].

Plane-Wave Packets and Their Limitation in Nonlinear Compton Scattering

We show that scattering boundary conditions are incompatible with a monochromatic radiation field for the case of nonlinear Compton scattering. We demonstrate this by showing that (a) in the monochromatic limit, gauge invariance in a given order of the expansion of the $S$ matrix is destroyed, and (b) the physical (scattering) boundary condition, that of a pulse of radiation incident on a target electron, cannot be reconstructed from the monochromatic limit of the $S$ matrix. We then proceed to show by an example that the frequency profile of the scattered radiation is a function of both the intensity and line shape of the incident field. Another interesting feature of this calculation is that the profile of the photon scattered at a fixed angle is significantly broadened in comparison with the incident line shape. The worked-out example is a simple model, that of a neutral, scalar "electron" interacting with a bilinear scalar, massless external field, which contains all the important features of nonlinear Compton scattering. While from the point of view of gauge invariance it is sufficient to treat the external radiation field as a one-dimensional wave packet, for a complete description of the problem it is necessary to describe the incident radiation (quanta) in terms of normalizable states. An estimate of the breakdown of the plane-wave approximation is included.