The Density Distribution of Electrons Induced by Multi-petawatt Laser Coupling with Gas Jets

We utilized the two-dimensional Particle-In-Cell (PIC) software EPOCH to elucidate the physical processes underlying petawatt laser ablation of nitrogen gas jets at four distinct jet pressures. The laser pulse was simulated as being incident directly onto a 1 mm nitrogen gas jet. A linearly polarized laser beam with a wavelength of 800 nm, a duration of 30 fs, a diameter of 5 μm, and an intensity of 5 × 1020 W/cm2 was employed. The electron densities of the nitrogen gas jets were set at 0.023 nc, 0.033 nc, 0.05 nc, and 0.0706 nc, where nc=1.7 × 1021 cm-3 denotes the critical plasma density for an 800 nm laser. Figures (a) to (d) depict the density distribution of hot electrons generated by the interaction between the multi-petawatt laser and the nitrogen gas jets at the aforementioned pressures.