arXiv subjects

Alexandre Bonatto

Publications and source records attributed to Alexandre Bonatto.

9 recordsLinked to original sources

arXiv2026

Bayesian Optimization of Molybdenum-99 Production by Laser Wakefield Acceleration Using Coupled PIC and Monte Carlo Simulations

This work applies Bayesian optimization to a loop composed of PIC simulations of laser electron acceleration and Monte Carlo (MC) simulations of bremsstrahlung-induced nuclear reactions, to maximize the production of molybdenum-99, the precursor of the most used radiopharmaceutical in nuclear medicine, metastable technetium-99. PIC and MC simulations are computationally intensive, and besides reducing the time spent, the Bayesian optimization coupling both simulations resulted in an improvement of an order of magnitude in the $^\text{99}$Mo yield over a previous work, in which the output of an optimization loop based solely on PIC simulations was used a posteriori to estimate $^{99}\mathrm{Mo}$ production through a MC simulation.

physics.acc-ph↗

arXiv2026

Resonant Excitation of Surface Plasmon for Wakefield Acceleration by Beating GW Lasers on Smooth Cylindrical Surface

We present a theoretical and numerical study of resonant surface-plasmon (SP) excitation driven by the beating of two co-propagating laser pulses on a smooth cylindrical plasma-vacuum interface. Analytical expressions for the SP dispersion relation, field amplitude, geometric coupling factor, and resonance conditions are derived and validated by fully three-dimensional particle-in-cell simulations. We reveal that curvature-induced geometric effects can substantially modify the SP dispersion and enable resonant matching by laser beat waves. This is inaccessible in planar geometries or with a single laser. Under matched resonance conditions, a high-amplitude SP-based wakefield can be generated by a few gigawatt lasers, placing this mechanism within reach of state-of-the-art fibre lasers. It therefore opens a route toward portable laser-driven plasma wakefield accelerators.

physics.plasm-ph↗

arXiv2025

Coherent synchrotron radiation by excitation of surface plasmon polariton on near-critical solid microtube surface

Coherent synchrotron radiation (CSR) is crucial for the development of powerful ultrashort light sources. We present a mechanism for generating CSR in the form of generalised superradiance, based on surface plasmon polaritons (SPPs), which are resonantly excited on a solid, near-critical-density inner surface of a microtube. A high-intensity, circularly polarised laser pulse, propagating along the microtube axis, efficiently couples the cylindrical SPP modes. This process creates azimuthally structured, rotating electromagnetic fields. These rotating fields subsequently confine, modulate, and directly accelerate surface electrons to emit CSR in the Vavilov-Cherenkov angle. We further demonstrate that by improving the azimuthal symmetry of these electrons, the helical modulation enables CSR emission across all azimuthal directions in the form of isolated harmonics, significantly enhancing radiation intensity even when full coherence is imperfect. Our full 3D Particle-in-Cell simulations indicate this scheme can generate X-rays with coherence enhanced by up to two orders of magnitude compared to incoherent emission. The challenges to experimentally realise this scheme are discussed, including the need for high-contrast lasers to prevent pre-plasma formation and the demanding tolerances for microtube fabrication and alignment, while these challenges are not beyond the scope of existing or near-future experimental capabilities.

physics.plasm-ph↗

arXiv2025

Leaky surface plasmon-based wakefield acceleration in nanostructured carbon nanotubes

Metallic carbon nanotubes (CNTs) can provide ultra-dense, homogeneous plasma capable of sustaining resonant plasma waves-known as plasmons-with ultra-high field amplitudes. These waves can be efficiently driven by either high-intensity laser pulses or high-density relativistic charged particle beams. In this study, we use numerical simulations to propose that electrons and positrons can be accelerated in wakefields generated by the leaky electromagnetic field of surface plasmons. These plasmons are excited when a high-intensity optical laser pulse propagates paraxially through a cylindrical vacuum channel structured within a CNT forest. The wakefield is stably sustained by a non-evanescent longitudinal field with $\si{TV/m}$-level amplitudes. This mechanism differs significantly from the plasma wakefield generation in uniform gaseous plasmas. Traveling at the speed of light in vacuum, with phase-matched focusing fields, the wakefield acceleration is highly efficient for both electron and positron beams. We also examine two potential electron injection mechanisms: edge injection and self-injection. Both mechanisms are feasible with current laser facilities, paving the way for experimental realization. Beyond presenting a promising pathway toward ultra-compact, high-energy solid-state plasma particle accelerators, this work also expands the potential of high-energy plasmonics.

physics.plasm-ph↗

arXiv2025

100s TeV/m-Level Particle Accelerators Driven by High-density Electron Beams in Micro Structured Carbon Nanotube Forest Channel

Solid-state materials, such as carbon nanotubes (CNTs), have the potential to support ultra-high accelerating fields in the TV/m range for charged particle acceleration. In this study, we explore the feasibility of using nanostructured CNTs forest to develop plasma-based accelerators at the 100 TeV/m-level, driven by high-density, ultra-relativistic electron beams, using fully three-dimensional particle-in-cell simulations. Two different acceleration mechanisms are proposed and investigated: the surface plasmon leakage field and the bubble wakefield. The leakage field, driven by a relatively low-density beam, can achieve an acceleration field up to TV/m, capable of accelerating both electron and positron beams. In particular, due to the direct acceleration by the driver beam, the positron acceleration is highly efficient with an average acceleration gradient of 2.3 TeV/m. In contrast, the bubble wakefield mechanism allows significantly higher acceleration fields, e.g. beyond 400 TV/m, with a much higher energy transfer efficiency of $66.7\%$. In principle, electrons can be accelerated to PeV energies over distances of several meters. If the beam density is sufficiently high, the CNT target will be completely blown out, where no accelerating field is generated. Its threshold has been estimated. Two major challenges in these schemes are recognised and investigated. Leveraging the ultra-high energy and charge pumping rate of the driver beam, the nanostructured CNTs also offer significant potential for a wide range of advanced applications. This work represents a promising avenue for the development of ultra-compact, high-energy particle accelerators. We also outline conceptual experiments using currently available facilities, demonstrating that this approach is experimentally accessible.

physics.acc-ph↗

arXiv2025

Electron Acceleration in Carbon Nanotubes

Wakefield wavelengths associated with solid-state plasmas greatly limit the accelerating length. An alternative approach employs 2D carbon-based nanomaterials, like graphene or carbon nanotubes (CNTs), configured into structured targets. These nanostructures are designed with voids or low-density regions to effectively reduce the overall plasma density. This reduction enables the use of longer-wavelength lasers and also extends the plasma wavelength and the acceleration length. In this study, we present, to our knowledge, the first numerical demonstration of electron acceleration via self-injection into a wakefield bubble driven by an infrared laser pulse in structured CNT targets, similar to the behavior observed in gaseous plasmas for LWFA in the nonlinear (or bubble) regime. Using the PIConGPU code, bundles of CNTs are modeled in a 3D geometry as 25 nm-thick carbon tubes with an initial density of $10^{22}$ cm$^{-3}$. The carbon plasma is ionized by a three-cycle, 800 nm wavelength laser pulse with a peak intensity of $10^{21}$ W cm$^{-2}$, achieving an effective plasma density of $10^{20}$ cm$^{-3}$. The same laser also drives the wakefield bubble, responsible for the electron self-injection and acceleration. Simulation results indicate that fs-long electron bunches with hundreds of pC charge can be self-injected and accelerated at gradients exceeding 1~TeV$/$m. Both charge and accelerating gradient figures are unprecedented when compared with LWFA in gaseous plasma.

physics.acc-ph↗

arXiv2025

Plasmonic excitations in graphene layers

The interaction of fast charged particles with graphene layers can generate electromagnetic modes. This wake effect has been recently proposed for short-wavelength, high-gradient particle acceleration and for obtaining brilliant radiation sources. In this study, the excitation of wakefields produced by a point-like charged particle moving parallel to a multilayer graphene array (which may be supported by an insulated substrate) is studied using the linearized hydrodynamic theory. General expressions for the excited longitudinal and transverse wakefields have been derived. The dependencies of the wakefields on the positions of the layers and the substrate, the velocity and the surface density have been extensively analyzed. This study provides a deeper understanding of the physical phenomena underlying plasmonic excitations in graphene layers, paving the way for potential applications of these structures in particle acceleration, nanotechnology and materials science.

physics.app-ph↗

arXiv2024

Plasmonic excitations in double-walled carbon nanotubes

The interactions of charged particles moving paraxially in multi-walled carbon nanotubes (MWCNTs) may excite electromagnetic modes. This wake effect has recently been proposed as a potential novel method of short-wavelength high-gradient particle acceleration. In this work, the excitation of wakefields in double-walled carbon nanotubes (DWCNTs) is studied by means of the linearized hydrodynamic theory. General expressions have been derived for the excited longitudinal and transverse wakefields and related to the resonant wavenumbers which can be obtained from the dispersion relation. In the absence of friction, the stopping power of the wakefield driver, modelled here as a charged macroparticle, can be written solely as a function of these resonant wavenumbers. The dependencies of the wakefields on the radii of the DWCNT and the driving velocity have been studied. DWCNTs with inter-wall distances much smaller than the internal radius may be a potential option to obtain higher wakefields for particle acceleration compared to single-walled carbon nanotubes (SWCNTs).

physics.acc-ph↗

arXiv2004

Nonlinear dynamics of electromagnetic pulses in cold relativistic plasmas

In the present analysis we study the self consistent propagation of nonlinear electromagnetic pulses in a one dimensional relativistic electron-ion plasma, from the perspective of nonlinear dynamics. We show how a series of Hamiltonian bifurcations give rise to the electric fields which are of relevance in the subject of particle acceleration. Connections between these bifurcated solutions and results of earlier analysis are made.

physics.plasm-ph↗