Twisted Petawatt Beams for Laser Driven Ion Acceleration

Relativistic vortex laser pulses received much attention for several laser acceleration concepts, such as doughnut wakefield acceleration, attosecond electron generation, proton acceleration, vortex harmonics generation, huge magnetic field generation and intense gamma ray production. Traditional beam shaping methods are based on phase mirrors or phase plates with sub-wavelength height patterning. However, scaling such optical elements to the full-aperture beam size of multi-PW lasers is very challenging. To prepare for these next generation experiments, we developed a method for generating ultra-intense vortex laser beams with set amount of angular momentum, using spiral-phase plasma mirrors. These micromachined single-use devices preserve their geometry during plasma formation, and may be used with arbitrary high laser power. These optical elements were used to generate Laguerre-Gaussian beams with l=1 orbital angular momentum at the ALEPH laser/CSU, at laser intensity of 2x10²⁰ W·cm^-2. We will show preliminary results on how orbital angular momentum was imprinted to the high-power beam, and how we employed these beams to manipulate the emission of TNSA ions from irradiated thin foils.