Stability of ionization-injection-based laser-plasma accelerators

Laser-plasma acceleration (LPA) is a compact technique to accelerate electron bunches highly relativistic energies, making it promising candidate power radiation sources for industrial or medical applications. We report on the generation of beams from an 80 MeV-level LPA setup based ionisation injection (II) over duration 8 hours at repetition rate 2.5 Hz, resulting in 72,000 consecutive shots with charge and acceleration. Over full operation time moving averages total beam 14.5 pC between 70-80 MeV did not drift detectable level. The largest source shot-to-shot jitter was (26% standard deviation), which most strongly correlated fluctuations plasma density (3.6% deviation). Particle-in-cell simulations demonstrate that this chiefly caused by stronger laser self-focusing higher plasmas, significantly increased ionised along emittance beam. nonlinearity process imposes tight constraints reproducibility laser-plasma conditions required low II-LPA output if plays role evolution.