# A New Line for Laser-Driven Light Ions Acceleration and Related TNSA Studies
## 1 Introduction  
The development of novel ion acceleration techniques based on ultra-intense lasers has been developing rapidly in the past decades due to the dramatic progress of laser systems capable of delivering increasingly higher power laser pulses. Based on these developments, laser-drivenacceleration is now moving from pure scientific exploration to applications. As described in details in several recent review papers, the primary process known as Target Normal Sheath Acceleration (TNSA) [1] is a robust mechanism to accelerate light ions from laser interaction with thin foil targets with exceptional properties including high brightness and high spectral cut-off, high directionality and laminarity, as well as short pulse duration. The process has been explored for a wide range of laser and target parameters in addition to target specifications [2], and has proven to be reliable and relatively easy to implement to accelerate light ions such as protons, deuterons, boron, carbon, oxygen, to energies up to several tens of MeV using large laser systems producing sub-ps pulses with tens or hundreds of Joules per pulse. The main challenges of the current research on TNSA include the control of acceleration parameters, namely cut-off energy, beam divergence, charge, and emittance. At the same time, experimental investigation is also being dedicated to target optimization and engineering, looking at different properties of surface, geometry, and conductivity. Finally, post-acceleration control is being tackled with special attention to selection, collimation [3], and, eventually, injection in secondary acceleration structures, even using miniature target-driven guiding devices [4].  
Indeed, ions beams produced with TNSA are ideal for applications where high ion flux is required with relatively large energy spread. Examples of applications include injectors for high power ion beams, neutron generation [5] for high power ion beams, and probes for fast evolving phenomena like the ultrafast charging of laser-heated samples [6]. Additionally, laser-driven ion beams have been proposed for space radiation studies and electronic components testing [7]. A more specific application with potential impact on industry and cultural heritage is the proton-induced X-ray emission spectroscopy (PIXE), which may be applicable with currently achievable TNSA performances and may strongly benefit from the compactness of a multi-MeV laser-driven ion source [8]. For these applications to emerge, the operation of laser-driven ion acceleration should be practical and reliable. In this context, the operation of a compact, high-intensity proton beam line at 10 MeV has been demonstrated recently [9]. However, for practical applications, compact, Joule-scale laser systems in the sub-100 fs domain [10] are much more attractive [11] for their higher repetition rate, potentially reaching the 100 Hz or even the kHz range with diode-pumping [12], which may allow future laser-driven accelerators to reach a repetition rate in the kHz range. Here, we describe a new initiative aimed at the construction of an all-optical accelerator line for light ions using a multi-J class, femtosecond laser system. The line for laser-driven light ions acceleration (L3 IA) project has the purpose of establishing an outstanding beam-line operation of a laser-plasma source in Italy, taking advantage of the results achieved so far in this field by the precursor experimental campaigns [13] and numerical modeling. The beam-line will operate at a newly developed sub-petawatt (PW) scale laser installation to enter the parameter range of ion acceleration currently being explored by leading European laboratories in this field, and will provide an advanced test facility for the development and exploitation of laser-driven ion sources. The beam-line development is linked to a strong research and development programme with clear goals, deliverables, and objectives, implementing the required laser-plasma technology and beam diagnostics and control techniques.