Experimental and theoretical study of plasma processes affected by strong laser generated magnetic fields is reported. The PALS laser system operating at 3 ω (438.5 nm) delivered intensities up to 1 × 1016 W cm−2 on targets. By using a special target system consisting of a Cu foil connected to a sub-mm coil, magnetic fields up to the level of 10 T were generated. This is 1.4 times higher than the field generated with a 1.315 mm (1 ω) laser beam at a comparable intensity. We found that these fields were sufficiently strong to modify plasma blow-off from the foil which resulted in the changed expansion dynamics and increased energy of hot electrons (HE) by 20%–40% compared to the plasma unaffected by the magnetic field. To obtain complementary experimental data, a complex diagnostic system was used enabling the visualization of the plasma expansion process both in visible light (3-frame composite interferometry) and in the soft x-ray region (4-frame pinhole x-ray camera) together with measurements of the HE parameters using two-dimensional imaging of the Kα line emission from the Cu target and electron spectroscopy. Experimental data obtained from the angular distribution of electron energy spectra were used for three-dimensional (3D3V) numerical PIC simulations using a modified EPOCH code. By including interactions between ions, protons, hot and thermal electrons in forward and backward propagating particles, the effects of the magnetic field on the flux of HE were visualized and compared with the experiment. The PIC simulation confirmed that the interaction of the HE flux with the magnetic field generated by the target-coil system leads to an increased flux energy. However, this increase is accompanied by increased complexity of the spatial structure and heterogeneity of the flux as well as its angular divergence.
This paper investigates how strong magnetic fields generated by laser-irradiated targets can affect the behavior of hot electrons and ions in the resulting plasma. The researchers used a specialized target system to generate magnetic fields up to 10 Tesla, which significantly increased the energy of hot electrons compared to plasma without the magnetic field. Experiments and simulations showed that the magnetic field alters the spatial structure and angular distribution of the hot electron flux.