Multi-petawatt Laser Research Articles

All-optical nonlinear Compton scattering performed with a multi-petawatt laser

All-optical nonlinear Compton scattering performed with a multi-petawatt laser

Fundamental physics opportunities with multi-petawatt- and multi-megaJoule-class facilities

In this invited paper, I will touch on some highlights from my research career in the Clarendon Laboratory and in the Central Laser Facility, Rutherford Appleton Laboratory, obtained working in partnership with many outstanding international collaborators. These fall under the three broad themes. The first is novel laser-plasma interactions. The second theme is that of extreme field physics using multi-petawatt laser facilities. The third theme is that of inertial fusion studies. All of these studies indicate that an international, dual-use, 20-MJ Inertial Confinement Fusion (ICF)/Inertial Fusion Energy (IFE) facility, with the first 2-MJ at high repetition rate supplying single-shot high energy amplifiers, will open many new exciting avenues for both fundamental physics and high energy density science in the decades ahead.

Laser Proton Acceleration from a Near-Critical Imploding Gas Target.

The interaction between relativistic intense laser pulses and near-critical-density targets has been sought after in order to increase the efficiency of laser-plasma energy coupling, particularly for laser-driven proton acceleration. To achieve the density regime for high-repetition-rate applications, one elusive approach is to use gas targets, provided that stringent target density profile requirements are met. These include reaching the critical plasma density while maintaining micron-scale density gradients. In this Letter, we present a novel scheme for achieving the necessary requirements using optical laser pulses to transversely shape the target and create a colliding shock wave in both planar and cylindrical geometries. Utilizing this approach, we experimentally demonstrated stable proton acceleration and achieved up to 5MeV in a monoenergetic distribution and particle numbers above 10^{8} Sr^{-1} MeV^{-1} using a 1.5J energy on-target laser pulse. The Letter also reports for the first time an extend series of 200 consecutive shots that demonstrates the robustness of the approach and its maturity for applications. These results open the door for future work in controlling gas targets and optimizing the acceleration process for more energetic multipetawatt laser systems.

Photon emission and radiation reaction effects in surface plasma waves in ultra-high intensities

Manipulating and harnessing plasmonic phenomena in the ultra-relativistic regime reveal promising prospects for the use of surface plasma waves (SPW) to create high-energy particle and radiation sources in the next generation of multi-petawatt lasers. Indeed, relativistic high-charge electron bunches can be produced by SPW excited by ultra-high intensity femtosecond lasers impinging on a periodically modulated solid-density target. In this regime, there is good evidence that SPW excitation survives and that the produced electron bunches experience strong acceleration, thus emitting large amounts of electromagnetic radiation. Therefore, extending the study to ultra-high laser intensities (I>1021 W/cm2), the use of a resonant grating for SPW generation represents an interesting alternative to light sources, as the energy lost by electrons due to radiation emission is transferred to high-energy γ photons. In addition, we show that using a laser with wavefront rotation coupled with a tailored blazed grating improves photon emission in the ultra-relativistic regime of interaction.

Attosecond and nano-Coulomb electron bunches via the Zero Vector Potential mechanism

The commissioning of multi-petawatt class laser facilities around the world is gathering pace. One of the primary motivations for these investments is the acceleration of high-quality, low-emittance electron bunches. Here we explore the interaction of a high-intensity femtosecond laser pulse with a mass-limited dense target to produce MeV attosecond electron bunches in transmission and confirm with three-dimensional simulation that such bunches have low emittance and nano-Coulomb charge. We then perform a large parameter scan from non-relativistic laser intensities to the laser-QED regime and from the critical plasma density to beyond solid density to demonstrate that the electron bunch energies and the laser pulse energy absorption into the plasma can be quantitatively described via the Zero Vector Potential mechanism. These results have wide-ranging implications for future particle accelerator science and associated technologies.

Light-Matter Interaction near the Schwinger Limit Using Tightly Focused Doppler-Boosted Lasers.

Strong-field quantum electrodynamics (SF QED) is a burgeoning research topic dealing with electromagnetic fields comparable to the Schwinger field (≈1.32×10^{18} V/m). While most past and proposed experiments rely on reaching this field in the rest frame of relativistic particles, the Schwinger limit could also be approached in the laboratory frame by focusing to its diffraction limit the light reflected by a plasma mirror irradiated by a multipetawatt laser. We explore the interaction between such intense light and matter with particle-in-cell simulations. We find that the collision with a relativistic electron beam would enable the study of the nonperturbative regime of SF QED, while the interaction with a solid target leads to a profusion of SF QED effects that retroact on the interaction. In both cases, relativistic attosecond pair jets with high densities are formed.

QScatter: numerical framework for fast prediction of particle distributions in electron-laser scattering

The new generation of multi-PetaWatt laser facilities will allow tests of strong field quantum electrodynamics (QED), as well as provide an opportunity for novel photon and lepton sources. The first experiments are planned to study the (nearly) head-on scattering of intense, focused laser pulses with either relativistic electron beams or high-energy photon sources. In this work, we present a numerical framework that can provide fast predictions of the asymptotic particle and photon distributions after the scattering. The method detailed in this manuscript can include multiple features such as spatial and temporal misalignment between the laser and the scattering beam, broadband electron beams, and beam divergence. The expected mean energy, energy spread, divergence or other observables are calculated by combining an analytical description and numerical integration. This method can provide results within minutes on a personal computer, which would otherwise require full-scale 3D QED-PIC simulations using thousands of cores. The model, which has been compiled into an open-source code QScatter, may be used to support the analysis of large-size data sets from high-repetition rate experiments, leveraging its speed for optimization or reconstruction of experimental parameters.

Non-linear QED approach for betatron radiation in a laser wakefield accelerator

Laser plasma-based accelerators provide an excellent source of collimated, bright, and adequately coherent betatron-type x-ray pulses with potential applications in science and industry. So far the laser plasma-based betatron radiation has been described within the concept of classical Liénard–Wiechert potentials incorporated in particle-in-cell simulations, a computing power-demanding approach, especially for the case of multi-petawatt lasers. In this work, we describe the laser plasma-based generation of betatron radiation at the most fundamental level of quantum mechanics. In our approach, photon emission from the relativistic electrons in the plasma bubble is described within a nonlinear quantum electrodynamics (QED) framework. The reported QED-based betatron radiation results are in excellent agreement with similar results using Liénard–Wiechert potentials, as well as in very good agreement with betatron radiation measurements, obtained with multi-10-TW lasers interacting with He and multielectron N_2 gas targets. Furthermore, our QED approach results in a dramatic reduction of the computational runtime demands, making it a favorable tool for designing betatron radiation experiments, especially in multi-petawatt laser facilities.

A Scalable, High-Efficiency, Low-Energy-Spread Laser Wakefield Accelerator Using a Tri-Plateau Plasma Channel.

The emergence of multi-petawatt laser facilities is expected to push forward the maximum energy gain that can be achieved in a single stage of a laser wakefield acceleration (LWFA) to tens of giga-electron volts, which begs the question-is it likely to impact particle physics by providing a truly compact particle collider? Colliders have very stringent requirements on beam energy, acceleration efficiency, and beam quality. In this article, we propose an LWFA scheme that can for the first time simultaneously achieve hitherto unrealized acceleration efficiency from the laser to the electron beam of >20% and a sub-1% energy spread using a stepwise plasma structure and a nonlinearly chirped laser pulse. Three-dimensional high-fidelity simulations show that the nonlinear chirp can effectively mitigate the laser waveform distortion and lengthen the acceleration distance. This, combined with an interstage rephasing process in the stepwise plasma, can triple the beam energy gain compared to that in a uniform plasma for a fixed laser energy, thereby dramatically increasing the efficiency. A dynamic beam loading effect can almost perfectly cancel the energy chirp that arises during the acceleration, leading to the sub-percent energy spread. This scheme is highly scalable and can be applied to petawatt LWFA scenarios. Scaling laws are obtained, which suggest that electron beams with parameters relevant for a Higgs factory could be reached with the proposed high-efficiency, low-energy-spread scheme.

Spectroscopy of Metastable and Isomeric Nuclei with the Help of Multibeam Multipetawatt Lasers

Spectroscopy of Metastable and Isomeric Nuclei with the Help of Multibeam Multipetawatt Lasers

The Inverse Faraday Effect Induced by Radiation Friction during Irradiation of Dense Plasma with Crossed Multipetawatt Laser Beams

The Inverse Faraday Effect Induced by Radiation Friction during Irradiation of Dense Plasma with Crossed Multipetawatt Laser Beams

Simulations of spin/polarization-resolved laser–plasma interactions in the nonlinear QED regime

Strong-field quantum electrodynamics (SF-QED) plays a crucial role in ultraintense laser–matter interactions and demands sophisticated techniques to understand the related physics with new degrees of freedom, including spin angular momentum. To investigate the impact of SF-QED processes, we have introduced spin/polarization-resolved nonlinear Compton scattering, nonlinear Breit–Wheeler, and vacuum birefringence processes into our particle-in-cell (PIC) code. In this article, we provide details of the implementation of these SF-QED modules and share known results that demonstrate exact agreement with existing single-particle codes. By coupling normal PIC simulations with spin/polarization-resolved SF-QED processes, we create a new theoretical platform to study strong-field physics in currently running or planned petawatt or multi-petawatt laser facilities.

Gamma-flash generation in multi-petawatt laser–matter interactions

The progressive development of high power lasers over the last several decades enables the study of γ-photon generation when an intense laser beam interacts with matter, mainly via inverse Compton scattering at the high intensity limit. γ-ray flashes are a phenomenon of broad interest, drawing the attention of researchers working in topics ranging from cosmological scales to elementary particle scales. Over the last few years, a plethora of studies predict extremely high laser energy to γ-photon energy conversion using various target and/or laser field configurations. The aim of this article is to discuss several recently proposed γ-ray flash generation schemes, as a guide for upcoming γ-photon related experiments and for further evolution of the presently available theoretical schemes.

Study of particle acceleration by Laguerre–Gaussian ultra intense laser plasma interactions

In this work, simulations of multi-petawatt lasers in the range of ∼0.2 PW–∼100 PW with varying Laguerre–Gaussian (LG) azimuthal modes as well as linearly polarized (LP) and circularly polarized (CP) laser beams striking near critical density targets were studied by using three-dimensional particle in cell (PIC) codes. Particle acceleration mechanisms have a dependence on laser polarization and it affects the energy gained by the particles. It is known that laser pulses can be polarized helically by applying the LG distribution function to the fundamental Gaussian laser profile. In this study, differently polarized laser beams with varying powers were employed to study laser driven particle acceleration and compares accelerated charged particles’ energy spectra and angular distribution. It is seen that LG laser beams can accelerate higher energetic particles due to higher conversion efficiency compared to LP and CP laser beams. It is also seen that LG laser beams can collimate ions with a narrower spread compared to LP and CP beams. Furthermore, ions can have a smaller divergence angle with increasing azimuthal mode index when the laser is LG polarized. We also studied the energy deposition of these particles in a water cell obtained by the PIC codes for different laser parameters by using Geant4 Monte Carlo simulations which suggests that LG laser beam can be useful for the future hadron therapy applications.

Long-wavelength pulse generation via light-sail backscattering

The next generation of multipetawatt laser facilities may enable new opportunities in radiation-pressure driven ion-acceleration. Owing to the motion of the thin solid foil used as a target in such experiments, the laser light reflected from the surface will be Doppler downshifted. We show that the downshifted light can be correlated with the ion energies and may be used as a diagnostic of the acceleration mechanism. The possibility of using the back-scattered light in ion acceleration experiments to produce long-wavelength few-cycle pulses is also explored. The highest ion velocities are obtained in the light-sail regime, the theory of which is here extended to regimes with varying reflectivity due to a time-dependent intensity. The reflected pulse with a large Doppler redshift and approximately linear chirp may subsequently be compressed using a grating compressor to obtain a near single cycle pulse with long wavelength and relatively high intensity. Analytic estimates are supported by 1D3P relativistic particle-in-cell simulations.

Vacuum Birefringence Measurement via All-Optical Interferometric Schemes

All-optical vacuum birefringence experiments will get increasingly closer to feasibility as multi-petawatt laser facilities become operational around the World. Thus, the availability of focused laser intensities in the order of IL ∼ 1022 −1024 W/cm2 are to be expected in a focused spot size ∼ 3 − 5 μm. With these values, vacuum refraction indices in the order of Δn ∼ 10−11 − 10−9 are possible with an induced phase delay on a counterpropagating optical probe beam in the order of Δφ ∼ 10−9 −10−7 radians. We discuss two all-optical interferometric schemes and detail the Mach-Zender interferometric proposal. We consider this interferometric scheme fed by both classical and non-classical input light and with two detection schemes. We outline scenarios that are likely to lead to a feasible experimental implementation.

Relativistic Tunneling Ionization in Crossed Petawatt Laser Beams

A scheme is proposed for a two-beam experiment on multi-petawatt laser systems aimed at searching for relativistic effects in electron tunneling from deep levels of multiply charged ions. It is shown that the most efficient relativistic ionization will occur in the field of a standing wave that arises in the case of counter-propagating beams. Estimates are given showing that the observation of relativistic effects during the ionization of s-states of hydrogen-like ions with charge Z = 80{-} 90 is potentially possible at laser intensity in the beam overlap domain simeq {kern 1pt} 1025 W/cm2.

Tango Controls and data pipeline for petawatt laser experiments

Abstract The Centre for Advanced Laser Applications in Garching, Germany, is home to the ATLAS-3000 multi-petawatt laser, dedicated to research on laser particle acceleration and its applications. A control system based on Tango Controls is implemented for both the laser and four experimental areas. The device server approach features high modularity, which, in addition to the hardware control, enables a quick extension of the system and allows for automated data acquisition of the laser parameters and experimental data for each laser shot. In this paper we present an overview of our implementation of the control system, as well as our advances in terms of experimental operation, online supervision and data processing. We also give an outlook on advanced experimental supervision and online data evaluation – where the data can be processed in a pipeline – which is being developed on the basis of this infrastructure.

Optical synchronization technique for all-optical Compton scattering.

In all-optical Compton scattering driven by a multi-petawatt laser, it is critical to have accurate spatiotemporal synchronization between the ultrarelativistic electron bunch and the ultrahigh-intensity laser beam. Such a synchronization was realized by using two complementary optical setups. The first setup, used for the initial synchronization, recorded the spatial interferogram between the two femtosecond lasers used for a GeV electron beam production and an ultrahigh scattering laser beam. The second one, consisting of spatial and spectral interferometers, measured the time delay between the two laser beams in the range of 0-200fs in real time. These monitoring systems played an essential role in conducting Compton scattering experiments.

Towards bright gamma-ray flash generation from tailored target irradiated by multi-petawatt laser

One of the remarkable phenomena in the laser-matter interaction is the extremely efficient energy transfer to gamma -photons, that appears as a collimated gamma -ray beam. For interactions of realistic laser pulses with matter, existence of an amplified spontaneous emission pedestal plays a crucial role, since it hits the target prior to the main pulse arrival, leading to a cloud of preplasma and drilling a narrow channel inside the target. These effects significantly alter the process of gamma -photon generation. Here, we study this process by importing the outcome of magnetohydrodynamic simulations of the pedestal-target interaction into particle-in-cell simulations for describing the gamma -photon generation. It is seen that target tailoring prior the laser-target interaction plays an important positive role, enhancing the efficiency of laser pulse coupling with the target, and generating high energy electron-positron pairs. It is expected that such a gamma -photon source will be actively used in various applications in nuclear photonics, material science and astrophysical processes modelling.