Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, activeplasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices.

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Laser-driven particle acceleration, obtained by irradiation of a solid target using an ultra-intense (I > 1018 W/cm2) short-pulse (duration <1 ps) laser, is a growing field of interest, in particular for its manifold potential applications in different domains. Here, we provide experimental evidence that laser-generated particles, in particular protons, can be used for stress testing materials and are particularly suited for identifying materials to be used in harsh conditions. We show that these laser-generated protons can produce, in a very short time scale, a strong mechanical and thermal damage, that, given the short irradiation time, does not allow for recovery of the material. We confirm this by analyzing changes in the mechanical, optical, electrical, and morphological properties of five materials of interest to be used in harsh conditions.

The development of compact accelerator facilities providing high-brightness beams is one of the most challenging tasks in field of next-generation compact and cost affordable particle accelerators, to be used in many fields for industrial, medical and research applications. The ability to shape the beam longitudinal phase-space, in particular, plays a key role to achieve high-peak brightness. Here we present a new approach that allows to tune the longitudinal phase-space of a high-brightness beam by means of a plasma wakefields. The electron beam passing through the plasma drives large wakefields that are used to manipulate the time-energy correlation of particles along the beam itself. We experimentally demonstrate that such solution is highly tunable by simply adjusting the density of the plasma and can be used to imprint or remove any correlation onto the beam. This is a fundamental requirement when dealing with largely time-energy correlated beams coming from future plasma accelerators.High-brightness electron beams are nowadays used for many applications like, for instance, Inverse Compton Scattering [1,2], the generation of THz [3,4], Free Electron Laser (FEL) radiation [5-8] and for new plasmabased acceleration techniques [9][10][11][12]. The generation of such beams always require manipulations of their longitudinal phase-space (LPS) in order to achieve peak currents as large as required by the specific task. The ability to shape the energy and temporal profiles is thus of paramount importance. In FEL facilities, for instance, peak currents of several kA are produced by longitudinally compressing a time-energy correlated (i.e. chirped ) beam in a dispersive magnetic chicane, where the path length is energy dependent [7,13]. The manipulation of the LPS is also a fundamental step in view of the development of new compact machines that exploit advanced acceleration techniques based on plasma wakefields. In this case accelerating fields up to tens of GV/m, ∼ 2−3 orders of magnitude larger than conventional radio-frequency (RF) structures, have been demonstrated allowing to produce GeV level beams in few centimeters [12,[14][15][16]. However, due to the shortness of the accelerating field wavelength a large correlated energy spread is imprinted on the accelerated beam, making difficult to transport the beam using conventional magnetic optics (like solenoids and quadrupoles), due to chromatic effects. In this case, a technique able to remove such an energy-chirp must be foreseen.In this Letter we discuss a new approach that allows to tune the beam LPS by using the wakefields excited in a plasma channel. Other techniques based on the use of metallic [17,18] or dielectric structures [19][20][21] have been also demonstrated. However, in the first case the imprinted energy-chirps cannot exceed few MeV/m while in the second one the tunability is rather limited, depending on the aperture and size of the employed devices. -250 -200 -150 -100 -50 0 50 100 150 z (um) 97.5 98 98.5 99 99.5 100 100.5 Energy (MeV) -60 -50 -...