Laser electron acceleration on curved surfaces

Abstract

Electron acceleration by relativistically intense laser beam propagating along a curved surface allows to split softly the accelerated electron bunch and the laser beam. The presence of a curved surface allows to switch an adiabatic invariant of electrons in the wave instantly leaving the gained energy to the particles. The efficient acceleration is provided by the presence of strong transient quasistationary fields in the interaction region and a long efficient acceleration length. The curvature of the surface allows to select the accelerated particles and provides their narrow angular distribution. The mechanism at work is explicitly demonstrated in theoretical models and experiments.

Strongly magnetized plasma produced by interaction of nanosecond kJ-class laser with snail targets

“…This is particularly visible at later times, even a dozen ns after the maximum of the laser pulse (see t = 13.3 ns). The persistence of this structure in the very late stages of expansion may be caused by freezing of the magnetic field in the formed plasma due to strong magnetization of the stream, in accordance with the ST target operational concept presented in [5,6]. The structure of the interference fringes turns out to be readable enough to obtain quantitative information on the magnetic field distribution and electron density for selected interferogram sequences.…”

“…In the first phase, the radially imploding plasma develops instabilities in the form of current 'jets' propagating toward the center of the target (see above and [23]). The currents inside the plasma propagating to the center of the target have clockwise-directed (effect of anticlockwise movement of electrons) components [5,6] parallel to the surface of the snail. These observed currents increase the magnetic field in the center of the target and reduce the field in the denser plasma closer to the target surface.…”

“…The use of pulse generators or permanent magnets is limited by induction values up to a dozen Tesla [1,2]. A particularly interesting alternative for the production of magnetized plasma streams suitable for various applications are targets with a special capacitor coil target (CCT) [3,4] and snail target (ST) [5,6] design, in which the spontaneous magnetic fields are generated by an interaction of the intense laser beam with (i) a capacitor or a disk, in the case of CCT targets, or (ii) a spiral-shaped ribbon for ST targets. Experiments with CCT targets conducted at LULI [3,7] and GEKKO-XII [4] demonstrated the generation of magnetic fields above 500 T. Much higher magnetic fields reaching tens of kT (hundreds of Megagauss (MGs)) can be obtained using ST targets irradiated in the relativistic intensity domain [5,6,8], which opens new horizons for various applications, e.g.…”