Design of plasma shutters for improved heavy ion acceleration by ultra-intense laser pulses

Abstract

In this work, we investigate the application of the plasma shutters for heavy ion acceleration driven by a high-intensity laser pulse. We use particle-in-cell (PIC) and hydrodynamic simulations. The laser pulse, transmitted through the opaque shutter, gains a steep-rising front and its peak intensity is locally increased at the cost of losing part of its energy. These effects have a direct influence on subsequent ion acceleration from the ultrathin target behind the shutter. In our 3D simulations of silicon nitride plasma shutter and a silver target, the maximal energy of high-$ Z $ ions increases significantly when the shutter is included for both linearly and circularly polarized laser pulses. Moreover, application of the plasma shutter for linearly polarized pulse results in focusing of ions towards the laser axis in the plane perpendicular to the laser polarization. The generated high energy ion beam has significantly lower divergence compared to the broad ion cloud, generated without the shutter. The effects of prepulses are also investigated assuming a double plasma shutter. The first shutter can withstand the assumed sub-ns prepulse (treatment of ns and ps prepulses by other techniques is assumed) and the pulse shaping occurs via interaction with the second shutter. On the basis of our theoretical findings, we formulated an approach towards designing a double plasma shutter for high-intensity and high-power laser pulses and built a prototype

Spiral pulse generation and subsequent ion acceleration via ultra-thin foil and circularly polarized laser pulse

“…Both of these effects has been attributed to the more intense laser-plasma dynamics when the pulse is firstly shaped by the plasma shutter, which results in development of high-density electron bunches. 5 On the contrary, without the shaping via the shutter, the bunches are pre-expanded by the relatively long low-intensity part of the laser pulse, as can be seen by comparing figures 3-a and 3-b. These bunches are well coupled with the corresponding generated magnetic field in the y-direction (Fig.…”

“…The shaping of the laser pulse via the interaction with the plasma shutter (i.e. generation of the steep front 1 and local increase of the maximal intensity 4 ) resulted in generation of a beam-like structure of accelerated silver ions from the main foil, 5 as can be seen in figure 1. The divergence of the ion beam is significantly reduced compared to the case without the plasma shutter, where a broad ion cloud is generated, 5 which is shown in the x-z plane, (i.e., the plane perpendicular to the laser polarization) in Fig.…”

“…The laser diffraction at the aperture and its subsequent constructive interference with the transmitted laser pulse also leads to a local intensity increase. 4 The shaping of the laser pulse subsequently leads to enhancement of the ion acceleration from the following target 5 in the regimes involving high radiation pressure 6 and subsequent relativistic induced transparency. 7,8 The use of a circularly polarized laser pulse in this kind of interaction can lead to the generation of a spiral pulse.…”

Picosecond ramp of ultrashort laser pulse: its effect on laser-driven ion acceleration or plasma shutter

“…Plasma shutter is usually a thin solid foil or membrane which can be used for the improvement of laser pulse contrast [4], in addition to the techniques like double plasma mirror (DPM) [5]. DPM enables to filter out nanosecond ASE pedestal of femtosecond laser pulse, however, it is not sufficient to remove picosecond ramp of the pulse completely, which can also lead to substantial modifications in some targets, e.g.…”

Novel approach to TNSA enhancement using multi-layered targets—a numerical study

“…However, there is a limitation on how thin a target can be before it is destroyed prematurely by prepulses or the main laser pedestal [21,22]. Currently, there is ongoing effort in different directions (such as plasma mirrors [23][24][25] and plasma shutters [26][27][28]) aiming to improve laser contrast. It is worth noting, however, that improving contrast usually comes at the cost of reduced pulse energy.…”