Study of Ion acceleration through Laser-plasma interaction in LS-RPA regime

High-intensity laser irradiation of a suitable target can generate highly energetic ion beams by accelerating the ions in a much shorter length compared to the conventional accelerator. Laser-driven ion acceleration is of great importance because of its high compactness which can lead to reduced accelerator size and cost compared to the conventional one. Laser-driven ion beam has prospective application in cancer therapy, radiobiology, fast ignition of inertial confinement fusion as well as in other fields. Advancement in laser technology with much higher intensity and shorter pulse length increases the potential of generating accelerated ions with much higher energy. There are different mechanisms through which the ions get accelerated during the laser-plasma interaction and specific mechanisms are dominant for specific target and laser parameters. ‘Radiation pressure acceleration (RPA)’, one of the mechanisms of laser-driven ion acceleration, has the potential to generate ions with energies of several MeVs. This is the dominant mechanism for ion acceleration from ultra-thin solid foil targets using a circularly polarized ultra-short laser pulse. RPA can efficiently accelerate heavier ions (C6+ ) besides proton compared to other acceleration mechanisms. In our work, we are investigating the acceleration of C6+ ions from nanometre thin solid density (350 times critical density) target with the help of a 2D particle in cell simulation. A circularly polarised laser is considered with a peak intensity of 6 × 1020W/cm2, central wavelength 800nm, and pulse duration of 40fs full width at half maximum. An optimum thickness exists in this target thickness range for which we get the maximum peak energy of C6+ ions. The change in the peak energy has been investigated if the intensity of the laser is increased by reducing the laser focal spot area that is by tightly focusing the pulse. This has been compared with the case if the laser intensity is increased by increasing the laser energy instead of tightly focusing it.