## 1 Introduction  
Over the past few decades, since the advent of the Chirped Pulse Amplification (CPA) technique [1], the advancement of high-intensity, ultra-short laser systems (now commonly operating at sub-petawatt levels and beyond [2]) has ushered in new opportunities for a diverse range of experiments exploring the physics of high-intensity laser interaction with matter. These experiments are relevant in various fields, including high-energy density science [3], high-gradient particle acceleration [4; 5; 6; 7], and laboratory astrophysics [8].  
Among these endeavours, laser-based particle acceleration stands out due to its potential to significantly impact multiple scientific domains and its applications in secondary radiation sources [9]. This method relies on well-established processes such as the Target Normal Sheath Acceleration (TNSA) scheme, with potential implications for cancer therapy, able to deliver ion beams in the multi-MeV energy range and beyond [10], and the Laser Wakefield Acceleration (LWFA) scheme, capable of accelerating electrons to multi-GeV energies [11]. Compared to traditional RF-driven systems, these innovative accelerators offer compelling features such as extraordinarily high acceleration gradients (up to hundreds of GV/m) leading to compact designs, ultra-short pulse durations in the picosecond (ps) down to femtosecond (fs) range, and reduced construction and maintenance costs. These characteristics have sparked considerable interest in further developments to explore the physics and applications of high-intensity laser-matter interaction yields. Indeed, these systems are increasingly finding applications in various scientific fields, particularly in biomedicine for particle and high-energy secondary radiation for both diagnosis and therapy [12; 13; 14].  
In this context, the Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME) has been designed and installed in the SPARC LAB Test Facility [15] to explore the processes underlying the laser-matter interaction at extreme intensities (up to \(10^{20}\) W/cm\({}^{2}\)) and to become an operational facility delivering stable laser-driven beamlines of ions, electrons, and X-ray radiation, within the EuAPS [16] and EuPRAXIA [17] projects focused on creating a compact European end-user plasma accelerator by utilizing the latest laser technologies and pioneering advancements in plasma acceleration.  
Additionally, the FLAME laser's capabilities enable a broad spectrum of scientific inquiries, from fundamental physics to applied research, by adopting the generated high-energy electron beams and secondary radiation sources, opening new avenues for experimental investigations. Finally, this work is expected to significantly contribute to the understanding and development of future advanced compact high-energy particle accelerators and radiation sources.  
This paper is organized as follows. The layout and features of the 200 TW FLAME laser, delivering 30 fs, 6 J laser pulses at 800 nm, are presented in Section 2. In Section 3, we describe the performed experimental campaigns both adopting the auxiliary, low-energy, ultra-short, high repetition rate beamline, and the main, high-energy, ultra-short, low repetition rate beamline at the FLAME test facility exploring different acceleration schemes as the LWFA and the TNSA.  
Moreover, the implemented laser, particle, and plasma diagnostics with comprehensive descriptions of their main features are reported. Within Section 3.2.1, we present an in-house, non-destructive, single-shot, temporally resolved diagnostics based on Electro-Optical Sampling [18] (EOS), which can record ultra-short electromagnetic pulses (EMPs) and relativistic electrons with femtosecond resolution [19; 20; 21; 22; 23]. In laser-solid target interaction experimental campaigns, this diagnostic tool provides a more detailed picture of the ultra-fast dynamics of these phenomena on a sub-picosecond timescale.