Magnetized plasma studies are necessary for many applied studies including laser-driven inertial fusion, modeling astrophysical relevant phenomena, as well as innovative industrial and medical applications. An interesting method of generating highly magnetized plasma can be based on interaction of a laser with spiral-shaped cavity (snail-like) targets. The target shaped in this way can represent a central area of a spherical pellet that is not irradiated radially, but through an entrance hole allowing the laser beam to almost impact its inner surface tangentially [15]. In the reported experiment, snail targets of various diameters were irradiated by linearly or circularly polarized radiation of the PALS iodine laser delivering ~500 J, 350-ps and 1.315-μm pulses on targets. A 3-frame complex interferometry demonstrated that plasma is generated on the entire inside and outside surface of the snail-target, starting from the very beginning of the laser-target interaction. The time resolved records of the magnetic field and the electron density distribution inside and outside the snail-target characterize the changes in the structure of the magnetized plasma. Inside the target, the magnetic field survives long after the termination of the laser-matter interaction, namely longer than 10 ns. Compared to a circularly polarized laser pulse, the irradiation of targets with a p-polarized beam increases both the emission of hot electrons and the intensity of the magnetic field. The emission of hot electrons is not isotropic, and their energy distribution cannot be characterized by a single temperature.

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Electron acceleration by laser pulses with high repetition rate can be used for technical applications. To reach conditions for the wake-field laser acceleration, it was demonstrated recently in experiments that it is beneficial to use near single cycle laser drive pulses with sub-4 fs duration, with narrow waists. To explore possible electron density ramp-up injection as an alternative to ramp-down and ionization injections, we performed numerical simulations of electron bunches generation in the ramp-up region. The PIC code Epoch2D and input parameters near to experiments were used. We assumed thin plasma slabs with super Gaussian density profiles of order 4-80, FWHM about 30 µm. We found that density ramp-up injected bunches can have charges several times higher than those obtained by ionization injection. There can be created a group of up to ten bunches in a sequence of bubbles, with not too mutually different maximum energy and charges. At oblique incidence of drive pulses on steep ramp up profiles, we find significant enhancement of the first bunch charge. For large slant angles -45 or 45 degrees, the bunch charge enhancement is about twenty times. We conclude that the ramp-up injection can be a useful alternative injection on steep enough density profiles.