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Particle acceleration in microstructures driven by ultrafast solid state lasers is a rapidly evolving area of advanced accelerator research, leading to a variety of concepts based on planar-symmetric dielectric gratings, hollow core fibers, photonic crystals, and plasmonic meta-surfaces. This approach leverages well-established industrial fabrication capabilities and the commercial availability of tabletop lasers to reduce cost, with demonstrated axial accelerating fields in the GV/m range. Wide-ranging international efforts have significantly improved understanding of gradient limits, structure design, particle focusing and transport, staging, and development of compatible low-emittance electron sources. With a near-term focus on low-current MeV-scale applications for compact scientific and medical instruments, as well as novel diagnostics capabilities, structure-based laser-driven accelerators have several key benefits that warrant consideration for future high-energy physics machines, including low beamstrahlung energy loss, modest power requirements, stability, and readiness of supporting technologies., Comment: arXiv admin note: substantial text overlap with arXiv:2203.03811, arXiv:1901.10370

Electron Cyclotron Resonance Ion Sources are currently the most efficient ion sources among those used in facilities dedicated to nuclear physics. The need for a more flexible magnetic field and RF injection system suggested to design and develop a different type of plasma trap, named Flexible Plasma Trap (FPT). The magnetic field of FPT is generated by means of three coils while microwaves in the range 4-7 GHz can be injected by three different inputs, one placed along the axis and two placed radially. FPT can work in different plasma heating schemes so it will be an ideal tool for studies of plasma and multidisciplinary physics. Moreover, a microwave launcher has been designed and installed to the FPT for launching microwaves with a variable tilt angle with respect to the magnetic field. This paper describes the characteristics of the FPT along with the preliminary results of plasma diagnostics.

This paper describes three-dimensional numerical simulations and Radio Frequency (RF) measurements of wave propagation in microwave-heated magnetized plasmas of ion sources. Full-wave solution of Maxwell's equations has been addressed through the Finite Element Method (FEM) commercial software COMSOL. Our numerical model takes into account the strongly inhomogeneous and anisotropic magnetized "cold" plasma medium. The simulations reproduce the main features of the wave-plasma interaction of the Flexible Plasma Trap (FPT) that recently came into operations at INFN-LNS. A two-pins RF probe has been ad-hoc developed and used as a plasmaimmersed antenna for measuring local wave electric fields in the FPT device. The measurements of plasma electron density and RF electric field, performed for different external magnetic field configuration, allowed a direct comparison with the assumed simulation model.

A numerical tool for analysing spatially anisotropic electron populations in electron cyclotron resonance (ECR) plasmas has been developed, using a trial-and-error electron energy distribution function (EEDF) fitting method. The method has been tested on space-resolved warm electrons in the energy range $2-20\,\mathrm{keV}$, obtained from self-consistent simulations modelling only electron dynamics in ECR devices, but lacked real-world validation. For experimentally benchmarking the method, we attempted to numerically reproduce the experimental X-ray emission spectrum measured from an argon plasma. Results of this analysis have provided crucial information about density and temperature of warm electrons, and competing distributions of warm and hot electron components. This information can be fed back to simulation models to generate more realistic data. Subsequent application of the numerical tool as described to the improved simulation data can result in continuous EEDFs that reflect the nature of charge distributions in anisotropic ECR plasmas. These functions can be also applied to electron dependent reactions, in order to reproduce experimental results, like those concerning space-dependent K$\alpha$ emissions.

In this paper we discuss the possibility to generate and accelerate proton nanobeams in fully dielectric laser-driven accelerators (p-DLAs). High gradient on-chip optical-power dielectric laser accelerators (DLAs) could represent one of the most promising way towards future miniaturized particle accelerator. A primary challenge for DLAs are small beam apertures having a size of the order of the driving laser wavelength where low charge high-repetition (or also CW) ultralow emittance nanobeams have to be transported. For electrons beams generation and acceleration, intense research activities are ongoing, and several demonstrations have been already obtained by using electrons nanotip (or flat photocathode) sources feeding dielectric microstructures. In this article we aim at the possibility to integrate a nanosource for the generation of a light ion or proton nano-beams suitable for the subsequent acceleration into sub-relativistic (low-beta) p-DLA stages. Such integration includes the idea to use a proton dielectric radiofrequency quadrupole (p-DRFQ) for bridging the gap between the accelerator front-end and the drift-tube and high-beta sections. The paper has been prepared as a white book including state-of-art technologies and new solutions that now put the ambitious frontier of a fully nanostructured proton accelerator into reach. Conceptual studies of p-DLAs here presented could enable table-top proton nano-beams for several applications: proton beam writing, nuclear reaction analysis at sub-micrometer scales, the construction of miniaturized Proton-Boron Nuclear Fusion based Reactors, biological analysis at the micrometer scale, ion beam analysis at the sub-cellular level, mini-beams ion therapy to spare the shallow tissues, proton irradiation of transistors, compact proton linac for neutron generation.

This paper discusses the capture of an ion beam in a magnetized plasma of an Electron Cyclotron Resonance Ion Source based Charge Breeder, as modelled by numerical simulations. As a relevant step forward with respect to previous works, here the capture is modeled by considering a plasma structure determined in a self-consisent way. The plasmoid-halo structure of the ECR plasma - that is consisting of a dense core (the plasmoid) surrounded by a rarefied halo - is further confirmed by the self-consistent calculations, having also some fine structures affected by the electromagnetic field distribution and by the magnetostatic field profile. The capture of Rb1+ ions has been investigated in details, vs. various plasma parameters, and then compared to experimental results., Comment: New results about a self-consistent modeling of magnetized plasmas

Nuclear astrophysics, the union of nuclear physics and astronomy, went through an impressive expansion during the last twenty years. This could be achieved thanks to milestone improvements in astronomical observations, cross section measurements, powerful computer simulations and much refined stellar models. Italian groups are giving quite important contributions to every domain of nuclear astrophysics, sometimes being the leaders of worldwide unique experiments. In this paper we will discuss the astrophysical scenarios where nuclear astrophysics plays a key role and we will provide detailed descriptions of the present and future of the experiments on nuclear astrophysics which belong to the scientific programme of INFN (the National Institute for Nuclear Physics in Italy)., Comment: Added paragraphs 5.6 and 7.2. Paragraph 7.3 (former 7.2) revised. Accepted for publication in La Rivista del Nuovo Cimento

PANDORA, Plasmas for Astrophysics, Nuclear Decays Observation and Radiation for Archaeometry, is planned as a new facility based on a state-of-the-art plasma trap confining energetic plasma for performing interdisciplinary research in the fields of Nuclear Astrophysics, Astrophysics, Plasma Physics and Applications in Material Science and Archaeometry: the plasmas become the environment for measuring nuclear decays rates in stellar-like condition (such as 7Be decay and beta-decay involved in s-process nucleosynthesis), especially as a function of the ionization state of the plasma ions. These studies are of paramount importance for addressing several astrophysical issues in both stellar and primordial nucleosynthesis environment (e.g. determination of solar neutrino flux and 7Li Cosmological Problem), moreover the confined energetic plasma will be a unique light source for high performance stellar spectroscopy measurements in the visible, UV and X-ray domains, offering advancements in observational astronomy. As to magnetic fields, the experimental validation of theoretical first and second order Land\'e factors will drive the layout of next generation polarimetric units for the high resolution spectrograph of the future giant telescopes. In PANDORA new plasma heating methods will be explored, that will push forward the ion beam output, in terms of extracted intensity and charge states. More, advanced and optimized injection methods of ions in an ECR plasma will be experimented, with the aim at optimizing its capture efficiency. This will be applied to the ECR-based Charge Breeding technique, that will improve the performances of the SPES ISOL-facility currently installed at Laboratori Nazionali di Legnaro-INFN. Finally, PANDORA will be suitable for energy conversion, making the plasma as a source of electromagnetic radiation, for applications in Material Science and Archaeometry.

Electron Cyclotron Resonance Ion Sources (ECRIS) progressed to higher and higher ion currents and charge states by adopting stronger magnetic fields (beneficial for confinement) and proportionally higher ECR frequencies. Further improvements would require the attainment of "triple products" of density, temperature and confinement time comparable with major fusion experiments. For this, we propose a new, toroidal rather than linear, ECRIS geometry, which would at the same time improve confinement and make better use of the magnetic field. Ion extraction is more complicated than from a linear device, but feasible, as our modelling suggests: single-particle tracings showed successful extraction by at least two techniques, making use respectively of a magnetic extractor and of ExB drifts. Additional techniques are briefly discussed., Comment: 17 pages, 10 figures. Revised manuscript submitted to Nucl. Instrum. Meth. A

We present the results of an experiment on plasma generation via laser ablation at 10^12 W/cm^2 of power intensity and in a nanosecond domain. Prompt electrons emission and complex plasma plume fragmentation were simultaneously observed for the first time in this laser intensity regime, along with a double electron temperature inside the plasma bulk surviving for a long time to the plume expansion. 1D PIC simulations are in agreement with experimental data as long as the emission of initial prompt electrons is considered. This assumption results to be the key to explain all the other experimental evidences., Comment: 5 pages, 6 figures, Europhysics Letters in press