X-ray production through betatron radiation emission from electron bunches is a valuable resource for several research fields. The EuAPS (EuPRAXIA Advanced Photon Sources) project, within the framework of EuPRAXIA, aims to provide 1–10 keV photons (X-rays), developing a compact plasma-based system designed to exploit self-injection processes that occur in the highly nonlinear laser-plasma interaction (LWFA) to drive electron betatron oscillations. Since the emitted radiation spectrum, intensity, angular divergence, and possible coherence strongly depend on the properties of the self-injected beam, accurate preliminary simulations of the process are necessary to evaluate the optimal diagnostic device specifications and to provide an initial estimate of the source’s performance. A dedicated tool for these tasks has been developed; electron trajectories from particle-in-cell (PIC) simulations are currently undergoing numerical analysis through the calculation of retarded fields and spectra for various plasma and laser parameter combinations. The implemented forward approach evaluation of the fields could allow for the integration of the presented scheme into already existing PIC codes. The spectrum calculation is thus performed in detector time, giving a linear complex exponential phase; this feature allows for a semi-analitical Fourier transform evaluation. The code structure and some trajectories analysis results are presented.

We present a new approach that demonstrates the deflection and guiding of relativistic electron beams over curved paths by means of the magnetic field generated in a plasma-discharge capillary. The active bending plasma (ABP) represents a promising solution that has been recently demonstrated with a proof of principle experiment. An ABP device consists of a curved capillary where large discharges (of the order of kA) are propagated in a plasma channel. Unlike conventional bending magnets, in which the field is constant over the bending plane, in the ABP, the azimuthal magnetic field generated by the discharge grows with the distance from the capillary axis. This features makes the device less affected by the beam chromatic dispersion so that it can be used to efficiently guide particle beams with non-negligible energy spreads. The study we present in the following aims to provide a theoretical basis of the main ABP features by presenting an analytical description of a single-particle motion and rms beam dynamics. The retrieved relationships are verified by means of numerical simulations and provide the theoretical matrix formalism needed to completely characterize such a new transport device. Published by the American Physical Society 2024

The SPARC_LAB facility, operating at the LNF-INFN laboratories in Frascati, has been devoted over the past years to R&D related to accelerators, advanced diagnostics, and generation of radiation ranging from THz to extreme UV light. The facility has recently been significantly upgraded and moved toward user-oriented applications, especially after the approval of two additional projects with the goal to develop radiation sources up to the soft x-ray range and in view of the EuPRAXIA project, whose preparatory phase is ongoing with the support of the European Commission. This paper summarizes the electron beam and radiation parameters and describes the layout and main features of the upgraded facility in view of future user-oriented experimental activities and applications.

A fundamental comparison between a magnetic undulator and an ion channel, or betatron, radiation from relativistic electrons is presented. While conventional theories nominally range from the undulator ( K < 1 ) to the wiggler ( K > 1 ) regime, they are only applicable for sufficiently large Lorentz factors ( γ 0 ≫ K ). They therefore do not account for high K / γ 0 cases, for which we show that particle trajectories and radiation characteristics strongly deviate from the linear predictions in both magnetic undulators and ion channels. This problem arises from the fundamental differences between a magnetostatically and electrostatically induced oscillation. A reformulation of both the ion channel betatron wavelength and amplitude, as well as the same parameters in a magnetic undulator, permits us to compare cases with equivalent oscillation period and amplitude in the two different scenarios. The notable differences in spectral features of the two radiation mechanisms can then be addressed via numerical simulations of single particle as well as full beam dynamics. Additionally, we identify and quantify a novel transverse orbit precession effect in ion channels for particles with initial angular momentum relative to the device axis. This effect, which is significant in cases of strong transverse kinetic energy oscillations, alters both the radiation divergence and the beam emittance. In this paper, we present this new theoretical framework and compare its results with numerical simulation applied to realizable experimental tests of such radiation sources.

X-rays production through betatron radiation emission from electron bunches is a valuable resource for several research fields. The EuAPS (EuPRAXIA Advanced Photon Sources) project, within the framework of the EuPRAXIA project, aims to provide 1-10 keV photons (soft X-rays) developing a compact plasma-based system designed to exploit self-injection processes that occur in highly nonlinear laser-plasma interaction (LWFA) to drive electron betatron oscillations. Since the emitted radiation spectrum, intensity, angular divergence, and possible coherence strongly depend on the properties of the self-injected beam, accurate preliminary simulations of the process are necessary to evaluate the optimal diagnostic device specifications. Dedicated tools for these tasks are under development: electron trajectories from particle-in-cell (PIC) simulations are currently undergoing numerical analysis through the calculation of retarded fields and spectra for various plasma and laser parameter combinations. At the same time, an analytical approach is being examined to obtain an expression for the emitted spectrum, assuming linear or quadratic electron energy variation. Code structure and some trajectories analysis results are presented.

Plasma discharge devices have recently emerged as compact and versatile tools for particle beam manipulation. Building upon the active plasma lens (APL) and its curved extension, the active plasma bending, this work introduces the concept of the plasma discharge undulator (PDU). In a PDU, a high-current discharge within a capillary generates an azimuthal magnetic field providing strong linear focusing [ O ( kT/m ) ] , while a controlled and periodical spatial modulation of the discharge axis acts as a geometric driving term. The resulting beam dynamics can be modeled as a forced harmonic oscillator, yielding a well-defined oscillation at wavelength λ PDU , distinct from the natural betatron wavelength λ β related to APL focusing. Proper injection conditions result in the suppression of collective betatron oscillations, significantly reducing the intrinsic undulator strength spread typical of conventional plasma undulators while allowing for matched beam transport thanks to strong APL focusing. Analytical models for particle trajectories and radiation emission are developed, and the one-dimensional requirements for free-electron laser (FEL) emission are evaluated, providing scaling relations and feasibility criteria for FEL operation in the proposed scheme. Theoretical estimates are validated through multiparticle simulations of beam dynamics and radiation emission, confirming that the PDU can operate in the short-period regime ( λ PDU of millimeters to centimeters) with tunable undulator strength K PDU , supporting narrow-band radiation emission. Numerical studies further demonstrate that the PDU is capable of sustaining seeded longitudinal microbunching analogous to that occurring in conventional magnetic undulators. The PDU thus provides a pathway toward miniaturized, tunable, fully plasma based light sources with enhanced control over focusing and spectral properties.