Optimization of critical-density gas jet targets for laser ion acceleration in the collisionless shockwave acceleration regime

Laser ion acceleration induced by high-power laser systems is nowadays an important research subject due to the large potential range of applications it could satisfy. Most of the available high-power laser facilities deliver only a few laser pulses per hour. The new facilities under development will operate at higher repetition rates (up to 10 Hz). Conventional target technologies (solid targets) and acceleration mechanisms (Target Normal Sheath Acceleration TNSA) used so far in laserbased ion acceleration are difficult to implement at high repetition rate. New ion acceleration mechanisms such as Collisionless Shockwave Acceleration (CSA) using high density gas jets represent therefore a promising alternative. Dense gas jet targets show several advantages such as constant refresh and negligible debris production. However, full comprehension of the fluid dynamics involved in the gas jet target production is fundamental for its optimization, and at present precise data is scarce. An ongoing study of design and optimization of supersonic gas jet nozzles for laser-based ion acceleration is presented.