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W. P. Leemans

Publications and source records attributed to W. P. Leemans.

At least 19 recordsLinked to original sources
arXiv2026

Programmable Focal Elongation and Shaping of High-Intensity Laser Pulses using Adaptive Optics

Controlling the intensity distribution of laser pulses in the focal region is essential for optimizing optically generated plasma waveguides and enabling advanced plasma acceleration techniques, including dephasingless wakefield acceleration. Here, we present a method for programmatic structuring of the high-intensity focal region of a standard off-axis parabolic mirror, extending the length of this region well beyond the Rayleigh length and enabling control over the longitudinal intensity distribution. The theoretical framework is validated through numerical simulations and experimental measurements. Further, we demonstrate the use of this technique in an existing plasma accelerator system using readily available hardware components. Finally, we illustrate the potential application of this method to multi-GeV laser plasma acceleration and the generation of flying foci, research areas which would significantly benefit from improved programmatic structuring of high-intensity laser pulses.

physics.plasm-ph↗
arXiv2022

Strong-Field QED Experiments using the BELLA PW Laser Dual Beamlines

The Petawatt (PW) laser facility of the Berkeley Lab Laser Accelerator (BELLA) Center has recently commissioned its second laser pulse transport line. This new beamline can be operated in parallel with the first beamline and enables strong-field quantum electrodynamics (SF-QED) experiments at BELLA. In this paper, we present an overview of the upgraded BELLA PW facility with a SF-QED experimental layout in which intense laser pulses collide with GeV-class laser-wakefield-accelerated electron beams. We present simulation results showing that experiments will allow the study of laser-particle interactions from the classical to the SF-QED regime with a nonlinear quantum parameter of up to $χ\sim$2. In addition, we show that experiments will enable the study and production of GeV-class, mrad-divergence positron beams via the Breit-Wheeler process.

physics.acc-ph↗
arXiv2022

Energy Compression and Stabilization of Laser-Plasma Accelerators

Laser-plasma accelerators outperform current radiofrequency technology in acceleration strength by orders of magnitude. Yet, enabling them to deliver competitive beam quality for demanding applications, particularly in terms of energy spread and stability, remains a major challenge. In this Letter, we propose to combine bunch decompression and active plasma dechirping for drastically improving the energy profile and stability of beams from laser-plasma accelerators. Realistic start-to-end simulations demonstrate the potential of these post-acceleration phase-space manipulations for simultaneously reducing an initial energy spread and energy jitter of $\sim1$-$2\%$ to ${\lesssim} 0.1 \%$, closing the beam-quality gap to conventional acceleration schemes.

physics.acc-ph↗
arXiv2022

Confined Continuous-Flow Plasma Source For High-Average-Power Laser Plasma Acceleration

Over the last decades, significant advances in high-power laser systems have enabled rapid progress in the development of laser-driven plasma accelerators. Today, the results obtained in beam stability and reproducibility present laser plasma acceleration as a viable and promising alternative to conventional accelerators. As several electron beam and secondary sources applications require high average currents, a major focus is now on increasing the beam's repetition rate. In the following, we introduce a novel plasma source for kHz electron acceleration, providing a continuous and spatially confined gas flow, while minimising the gas load in the acceleration chamber.

physics.acc-ph↗
arXiv2021

Design of a prototype laser-plasma injector for the DESY-II synchrotron

The present state of progress in laser wakefield acceleration encourages considering it as a practical alternative to conventional particle accelerators. A promising application would be to use a laser-plasma accelerator as an injector for a synchrotron light source. Yet, the energy spread and jitter of the laser-plasma beam pose a significant difficulty for an efficient injection. In this paper we propose a design of a prototype injector to deliver 500 MeV low-intensity electron bunches to the DESY-II electron synchrotron. The design utilizes presently available conventional accelerator technology, such as a chicane and an X-band radio frequency cavity, to reduce the energy spread and jitter of the electron beam down to a sub-per-mille level.

physics.acc-ph↗
arXiv2018

Direct Measurement of Focusing Fields in Active Plasma Lenses

Active plasma lenses have the potential to enable broad-ranging applications of plasma-based accelerators owing to their compact design and radially symmetric kT/m-level focusing fields, facilitating beam-quality preservation and compact beam transport. We report on the direct measurement of magnetic field gradients in active plasma lenses and demonstrate their impact on the emittance of a charged particle beam. This is made possible by the use of a well-characterized electron beam with 1.4 mm mrad normalized emittance from a conventional accelerator. Field gradients of up to 823 T/m are investigated. The observed emittance evolution is supported by numerical simulations, which suggest the potential for conservation of the core beam emittance in such a plasma lens setup.

physics.acc-ph↗
arXiv2017

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channel

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors, while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize simultaneous coupling of the electron beam and the laser pulse into a second stage. A curved channel with transition segment is used to guide a fresh laser pulse into a subsequent straight channel, while allowing the electrons to propagate in a straight channel. This scheme benefits from a shorter coupling distance and continuous guiding of the electrons in plasma, while suppressing transverse beam dispersion. With moderate laser parameters, particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration, while maintaining high capture efficiency, stability, and beam quality.

physics.plasm-ph↗
arXiv2017

On production and asymmetric focusing of flat electron beams using rectangular capillary discharge plasmas

A method for the asymmetric focusing of electron bunches, based on the active plasma lensing technique is proposed. This method takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus the ultrarelativistic electrons. The plasma and magnetic field parameters inside the capillary discharge are described theoretically and modeled with dissipative magnetohydrodynamic computer simulations enabling analysis of the capillaries of rectangle cross-sections. Large aspect ratio rectangular capillaries might be used to transport electron beams with high emittance asymmetries, as well as assist in forming spatially flat electron bunches for final focusing before the interaction point.

physics.plasm-ph↗
arXiv2016

Radiation Pressure Acceleration: the factors limiting maximum attainable ion energy

Radiation pressure acceleration (RPA) is a highly efficient mechanism of laser-driven ion acceleration, with with near complete transfer of the laser energy to the ions in the relativistic regime. However, there is a fundamental limit on the maximum attainable ion energy, which is determined by the group velocity of the laser. The tightly focused laser pulses have group velocities smaller than the vacuum light speed, and, since they offer the high intensity needed for the RPA regime, it is plausible that group velocity effects would manifest themselves in the experiments involving tightly focused pulses and thin foils. However, in this case, finite spot size effects are important, and another limiting factor, the transverse expansion of the target, may dominate over the group velocity effect. As the laser pulse diffracts after passing the focus, the target expands accordingly due to the transverse intensity profile of the laser. Due to this expansion, the areal density of the target decreases, making it transparent for radiation and effectively terminating the acceleration. The off-normal incidence of the laser on the target, due either to the experimental setup, or to the deformation of the target, will also lead to establishing a limit on maximum ion energy.

physics.plasm-ph↗
arXiv2015

Enhancing proton acceleration by using composite targets

Efficient laser ion acceleration requires high laser intensities, which can only be obtained by tightly focusing laser radiation. In the radiation pressure acceleration regime, where the tightly focused laser driver leads to the appearance of the fundamental limit for the maximum attainable ion energy, this limit corresponds to the laser pulse group velocity as well as to another limit connected with the transverse expansion of the accelerated foil and consequent onset of the foil transparency. These limits can be relaxed by using composite targets, consisting of a thin foil followed by a near critical density slab. Such targets provide guiding of a laser pulse inside a self-generated channel and background electrons, being snowplowed by the pulse, compensate for the transverse expansion. The use of composite targets results in a significant increase in maximum ion energy, compared to a single foil target case.

physics.plasm-ph↗
arXiv2015

Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection.

physics.plasm-ph↗
arXiv2015

Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy

The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (Magnetic Vortex Acceleration and hole-boring Radiation Pressure Acceleration) of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He3 ions, having almost the same penetration depth as He4 with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

physics.plasm-ph↗
arXiv2014

Controlling the spectral shape of nonlinear Thomson scattering with proper laser chirping

Effects of nonlinearity in Thomson scattering of a high intensity laser pulse from electrons are analyzed. Analytic expressions for laser pulse shaping in amplitude and frequency are obtained which control spectrum broadening for arbitrarily high laser pulse intensities. These analytic solutions allow prediction of the spectral form and required laser parameters to avoid broadening. The predictions are validated by numerical calculations. This control over the scattered radiation bandwidth allows of narrow bandwidth sources to be produced using high scattering intensities, which in turn greatly improves scattering yield for future x- and gamma-ray sources.

physics.plasm-ph↗
arXiv2014

Quasi-monoenergetic femtosecond photon sources from Thomson Scattering using laser plasma accelerators and plasma channels

Narrow bandwidth, high energy photon sources can be generated by Thomson scattering of laser light from energetic electrons, and detailed control of the interaction is needed to produce high quality sources. We present analytic calculations of the energy-angular spectra and photon yield that parametrize the influences of the electron and laser beam parameters to allow source design. These calculations, combined with numerical simulations, are applied to evaluate sources using conventional scattering in vacuum and methods for improving the source via laser waveguides or plasma channels. We show that the photon flux can be greatly increased by using a plasma channel to guide the laser during the interaction. Conversely, we show that to produce a given number of photons, the required laser energy can be reduced by an order of magnitude through the use of a plasma channel. In addition, we show that a plasma can be used as a compact beam dump, in which the electron beam is decelerated in a short distance, thereby greatly reducing radiation shielding. Realistic experimental errors such as transverse jitter are quantitatively shown to be tolerable. Examples of designs for sources capable of performing nuclear resonance fluorescence and photofission are provided.

physics.plasm-ph↗
arXiv2014

Plasma wakefield excitation by incoherent laser pulses: a path towards high-average power laser-plasma accelerators

In a laser plasma accelerator (LPA), a short and intense laser pulse propagating in a plasma drives a wakefield (a plasma wave with a relativistic phase velocity) that can sustain extremely large electric fields, enabling compact accelerating structures. Potential LPA applications include compact radiation sources and high energy linear colliders. We propose and study plasma wave excitation by an incoherent combination of a large number of low energy laser pulses (i.e., without constraining the pulse phases). We show that, in spite of the incoherent nature of electromagnetic fields within the volume occupied by the pulses, the excited wakefield is regular and its amplitude is comparable or equal to that obtained using a single, coherent pulse with the same energy. These results provide a path to the next generation of LPA-based applications, where incoherently combined multiple pulses may enable high repetition rate, high average power LPAs.

physics.plasm-ph↗
arXiv2013

Enhancement of maximum attainable ion energy in the radiation pressure acceleration regime using a guiding structure

Radiation Pressure Acceleration relies on high intensity laser pulse interacting with solid target to obtain high maximum energy, quasimonoenergetic ion beams. Either extremely high power laser pulses or tight focusing of laser radiation is required. The latter would lead to the appearance of the maximum attainable ion energy, which is determined by the laser group velocity and is highly influenced by the transverse expansion of the target. Ion acceleration is only possible with target velocities less than the group velocity of the laser. The transverse expansion of the target makes it transparent for radiation, thus reducing the effectiveness of acceleration. Utilization of an external guiding structure for the accelerating laser pulse may provide a way of compensating for the group velocity and transverse expansion effects.

physics.plasm-ph↗
arXiv2013

Snowmass 2013 Computing Frontier: Accelerator Science

This is the working summary of the Accelerator Science working group of the Computing Frontier of the Snowmass meeting 2013. It summarizes the computing requirements to support accelerator technology in both Energy and Intensity Frontiers.

physics.acc-ph↗