# A New Line for Laser-Driven Light Ions Acceleration and Related TNSA Studies
## 2 Materials and Methods: The ILIL-PW Laser Facility  
The L3 IA will be established at the Intense Laser Irradiation Laboratory and will be based at INO-CNR where the ILIL-PW laser installation features a >200 TW laser system, a beam transport line, and a multi-purpose interaction area with radiation shielding. An overview of the ILIL-PW facility is shown in Figure 1, while a summary of the main laser parameters is given in the table of Table 1. The 10-Hz front-end is shown schematically in Figure 2, with the oscillator producing 15 fs pulses at approximately 6 nJ. A \"booster\" unit amplifies the oscillator pulse to the 10 uJ level and is followed by a stretcher that delivers a chirped pulse with a duration of 600 ps to the regenerative amplifier. The mJ energy pulse is further amplified by a 5-pass amplifier followed by a 4-pass amplifier, finally delivering 600 mJ at 800 nm. The output pulses of the front-end are then transported to the final 4-pass amplifier, pumped by four Nd:YAG lasers (Titan6 by Amplitude Technologies) delivering a total of 24 J pulses at 532 nm at a maximum rep-rate of 5 Hz. The 800-nm pulse is thus amplified up to \(>\)7 J and compressed down to \(<\)25 fs. Pulse duration control is achieved through standard techniques based on acousto-optical devices placed in the front-end to achieve control of spectral gain, phase, and amplitude. The pulse energy losses due to acousto-optics devices are compensated in the amplification stages. Pump fluence throughout the front-end system is kept below 1 J/cm\({}^{2}\) to operate well below the Ti:Sa crystal damage threshold [14], yielding a typical energy extraction efficiency of less than 30%.  
The compressed pulse is then transported under vacuum to the octagonal interaction chamber via two remotely controlled, beam steering chambers. The beam is then focused on a target by an F/3 Off-Axis Parabolic (OAP) mirror to an intensity in excess of 10\({}^{20}\) W/cm\({}^{2}\). The interaction chamber is equipped with a remotely controlled motorized target mount with a sub-micrometer resolution capable of XYZ translation and azimuthal rotation around the vertical axis.  
The target mount was designed to enable a 100-mm range of positioning and withstand a load of up to 500 N in all directions of motion. These specifications ensure that the scanning of targets up to 100 mm \(\times\) 100 mm can be accomplished, enabling a large number of laser shots to be fired on a given target (typically up to 10\({}^{3}\)) before target replacement is required.  
The output from the front-end can be compressed independently to deliver 450 mJ in a 30 fs pulse with an M\({}^{2}\)\(<\) 1.5 to a separate interaction chamber, which is used for the pilot experimental activity. Cross-correlation measurement of the laser pulse show [15] that the front-end laser contrast  
\begin{table}
\begin{tabular}{c c c c} \hline
**MAIN BEAM** & **Front-end** & **1 st Phase** & **2 nd Phase** \\ \hline Wavelength (nm) & 800 & 800 & 800 \\ Pump Energy (J) & 1.8 & 12 & 24 \\ Pulse Duration (fs) & 40 & 30 & 25 \\ Energy Before Compression (J) & 0.6 & 4.7 & 7.9 \\ Energy After Compression (J) & 0.4 & \(>\)3 & \(>\)5 \\ Rep. Rate (Hz) & 10 & 1 & 2 \\ Max intensity on target (W/cm\({}^{2}\)) & 2 \(\times\) 10\({}^{19}\) & 2 \(\times\) 10\({}^{20}\) & 4 \(\times\) 10\({}^{20}\) \\ Contrast@100 ps & \(>\)10\({}^{9}\) & \(>\)10\({}^{9}\) & \(>\)10\({}^{10}\) \\ Beam Diameter (mm) & 36 & 100 & 100 \\ \hline \end{tabular}
\end{table}
Table 1: Summary table of the ILIL-PW laser parameters including the front-end and the full system after the two-step facility upgrade.  
Figure 1: Schematic view of the ILIL-PW facility at INO, including the main amplifier room, the shielded target area, and the laser-driven light ions acceleration (L3 IA) dedicated line. OAP: Off-Axis Parabolic.  
remains above \(10^{10}\) up to 10 ps before the peak of the pulse, and decreases to \(10^{6}\), 1 ps before the peak of the pulse.