Fig. 1. Evolution of (a) maximum intensity I, (b) on-axis electron density ρe, (c) beam radius r and (d) energy E of femtosecond laser pulse propagating in air with different η while the air pressure is 1 atm

Fig. 2. Spatial distribution of laser intensity I(r,z) at t=0 moment while the air pressure is 1 atm and η is (a) 0%, (b) 0.1%, (c) 0.5%, (d) 1.0%, (e) 5.0% and (f) 10.0%, respectively

Fig. 3. Evolution of the on-axis intensity I(t,z) with time and propagation distance while the air pressure is 1 atm and η is (a) 0%, (b) 0.1%, (c) 0.5% (d) 1.0%, (e) 5.0% and (f) 10.0%, respectively

Fig. 4. Evolution of (a) maximum intensity I, (b) on-axis electron density ρe, (c) beam radius r and (d) energy E of femtosecond laser pulse propagating in air with different η while the air pressure is 0.2 atm

Fig. 5. Spatial distribution of laser intensity I(r,z) at t=0 moment while the air pressure is 0.2 atm and η is (a) 0%, (b) 0.1%, (c) 0.5%, (d) 1.0%, (e) 5.0% and (f) 10.0%, respectively

Fig. 6. Evolution of the on-axis intensity I(t,z) with time and propagation distance while the air pressure is 0.2 atm and η is (a) 0%, (b) 0.1%, (c) 0.5% (d) 1.0%, (e) 5.0% and (f) 10.0%, respectively