Influence of target curvature on ion acceleration in radiation pressure acceleration regime

Abstract

Ion acceleration from submicron thick foil target irradiated by a circularly polarized laser is studied using multidimensional particle-in-cell simulations. Convex, flat, and concave target shapes are considered. Radius of curvature of curved target is of the order of laser width in transverse direction. Accelerated ion beam of highest peak energy and least energy spread is obtained from concave target, whereas total accelerated charge is highest in convex target. It is attributed to the change in the growth of transverse instabilities and geometrical effects due to target curvature in initial stages of acceleration process. The variation in the radius of curvature of the foil depends on the ratio of initial spot size to the radius of curvature. Faster reduction in curvature is achieved for tightly focused Gaussian pulses as conjectured by the model.

Numerical simulation of laser ion acceleration at ultra high intensity

“…It is important to note that at the onset of the ultra high intensity regime the improvements in maximum particle energy and angular distribution follow the trends observed in lower intensity cases previously studied in the literature [19], [21], [22], [25], [27]. While each of these target augmentations (curvature, microdot and cone structure) has its advantages, a composite target featuring all three attributes has the potential to produce higher quality proton and ion beams.…”

“…The target curvature has been demonstrated to have a significant effect both on the magnitude of the resulted electromagnetic field which accelerates the ions and on the ion angular distribution [19], [25], [27]. Coupling the improved characteristics resulted from a curved foil with a posterior side proton-rich microdot we expect to obtain high-energy collimated proton beams.…”

“…The hot electron density and temperature in the rear vacuum depend on the target geometrical and composition properties such as target curvature, pulse focusing structures and microdots for enhanced proton acceleration [18][19][20][21][22][23][24][25][26][27]. In order to optimize the laser accelerated particle beams we have investigated the proton and ion energy and the angular distribution by means of two-dimensional (2D) particle-in-cell (PIC) simulations of the interaction of ultrashort laser pulses with several microstructured targets.…”

Improving the particle beam characteristics resulting from laser ion acceleration at ultra high intensity through target manipulation – Numerical modeling

“…When referring to the baseline cases, the laser pulse is normal to the target surface in all points, thus the main laser absorption mechanism is heating [30]. As seen in the past, the target curvature has a significant effect both on the magnitude of the resulted electromagnetic field which accelerates the ions and on the ion angular distribution [1], [20], [26], [28]. Coupling the improved characteristics resulted from a curved foil with a posterior side proton-rich microdot we expect to obtain a better collimated, higher-energy proton beam.…”

“…The hot electron density and temperature in the rear vacuum depend on the target geometrical and composition properties such as target curvature, pulse focusing structures and microdots for enhanced proton acceleration [19][20][21][22][23][24][25][26][27][28]. This paper studies the effects of different target density profiles on the spatial distribution of the accelerated particles, the maximum energies achieved, and the characteristics of the electromagnetic fields using the same laser pulse parameters, corresponding to ones available using short pulse PW lasers like CETAL.…”