On November 15-16, 2021, more than 70MeV proton beam was achieved on PetaWatt laser of Shenguang II (SG II) 9th Beam, in Shanghai Institute of Optics and Mechanics. This is the highest output proton based on the Target Back Sheath Field Acceleration Mechanism (TNSA) in laser-driven proton acceleration experiments, which is carried out by researchers form Shanghai Laser Plasma Research Institute.
Laser signal-to-noise ratio and focal spot parameters in SG II 9th beam have been significantly improved by applying new technologies, such as OPCPA (first online application of PS-OPA), CPA energy flow and isolation optimization, transmittance enhancement and focal spot optimization, from April to November in 2021, which played a key role in improving the results of physical experiments.
Fig 1 (a) Contrast of OPCPA output, (b) SN of ns laser (Image by SIOM)
Fig 2 (a) Focal spot of output, (b) Recordings of RCF (Image by SIOM)