An overview of the 200 TW Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME) at the SPARC_LAB Test Facility at the National Laboratories of Frascati (LNF-INFN) is presented. The FLAME laser is employed to investigate different laser–matter interaction schemes, i.e., electron acceleration and secondary radiation sources through Laser Wakefield Acceleration (LWFA) or ion and proton generation through Target Normal Sheath Acceleration (TNSA), for a wide range of scientific areas including the biomedical applications. Finally, recently performed experimental campaigns within the EuAPS and EuPRAXIA frameworks are reported.

The EuPRAXIA EU project is at the forefront of advancing particle accelerator research and the development of photon sources through innovative plasma acceleration approaches. Within this framework, the EuAPS project aims to exploit laser wakefield acceleration to build and operate a betatron radiation source at the INFN Frascati National Laboratory. The EuAPS source will provide femtosecond X-ray pulses in the spectral region between about 1 and 10 keV, unlocking a realm of experimental ultrafast methodologies encompassing diverse imaging and X-ray spectroscopy techniques. This paper presents a description of the EuAPS betatron source, including simulations of the photon beam parameters, outlines the preliminary design of the dedicated photon beamline, and provides an insightful overview of its photon science applications.

Resonances play a crucial role in media sustaining oscillatory phenomena, such as plasmas. We show with experimental results and numerical simulations that the wakefields driven by individual successive bunches in overdense plasma superpose linearly, and that their amplitude increases along the train, under optimal coupling with plasma density oscillations. We also demonstrate, for the first time, that a train of bunches with increasing charge can be used to enhance the transformer ratio of the acceleration process, hence improving the energy-transfer efficiency.

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.

The Laser WakeField Acceleration (LWFA) process in a gas target requires laser and plasma diagnostics to monitor the interaction, such as a Mach-Zehnder interferometer for plasma density analysis. In addition, other diagnostics are used to characterize the accelerated particle beams and the secondary X-ray radiation produced, such as an energy spectrometer and a CCD-X camera. This X-ray radiation has distinctive features that open up the possibility of significant applications in fields such as materials science, biological research, medicine and industry. In the next few years, these radiation sources will become a good alternative to conventional ones due to the reduction in cost and the smaller dimension of such facilities. In this contribution, we present the diagnostics and the experimental results of several experimental campaigns carried out to characterize the LWFA process at the Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME) facility at the Laboratori Nazionali di Frascati-INFN in the framework of the EuPRAXIA Advanced Photon Sources (EuAPS) project.

The interaction of an ultra-short, high-power laser pulse with a solid target, in the so-called Target Normal Sheath Acceleration (TNSA) configuration, produces particles in the MeV range. Fast electrons can escape from the target after the interaction, inducing electrostatic fields on the order of TV/m close to the target surface. These fields accelerate MeV protons and heavy ions at the rear of the target, allowing them to escape. The complete process is difficult to probe, as it occurs on the sub-ps timescale. At the INFN-LNF SPARC_LAB test facility, single-shot diagnostics such as the Electro-Optical Sampling (EOS) are being developed and tested for time-resolved direct measurements of the produced electrons and associated longitudinal electric fields. Electrons are the core of the process, and their properties determine the following production of positive charge particles and electromagnetic radiation. Different target geometries and materials are being investigated to analyze the enhancement of fast electron emission and the correlation with positive charge production. Simultaneous observations of electron and proton beams have been performed using two diagnostic lines, the EOS for electrons and a time-of-flight (TOF) detector for protons. This work provides an overview of the previous experiments performed at SPARC_LAB dedicated to the TNSA characterization.