Generating High-charge Energetic Particle Bunches By The Interaction Of Two Intense Laser Pulses With Plasmas

A new scheme using two laser pulses is proposed in this article to improve the production of energetic electrons and ions in laser-plasma interaction.The background of laser-plasma electron/ion acceleration is briefly introduced here, such as the history for the usage of nuclear fusion energy, the condition of thermonuclear reaction, basic concepts of plasma physics and two potential methods to achieve confinement nuclear fusion re-action:magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). Meanwhile, some laser-plasma interactions related to ICF are also introduced here, such as ionization of mat-ters, particle motion in electromagnetic field, generation of laser-plasma wakefield and bubble, laser-plasma instabilities and laser-solid interactions.Based on the theories of Particle-In-Cell (PIC) simulation, we have developed a PIC code to investigate laser-plasma interactions involved in this article. Some technical details are described here, such as the pushing of macro particle, method of calculating charge and current, evolution of electromagnetic field and introducing of laser pulse. Meanwhile, according to former researches, some benchmarks are conducted to valid the abilities of our PIC code.The interaction of two energetic electron bunches generated in the wakefields of two intense intersecting laser pulses in rarefied plasmas is investigated using our PIC simulations. It is found that, with suitable intersection angle between the two laser pulses, the initially independent wake-field accelerated electron bunches can merged into a single one with high charge, energy, and nar-row energy spread. The dynamics of the laser-pulse intersection and wake-bubble merging process is also investigated, and the crucial roles of the intersection angle are pointed out and analyzed.As for ion acceleration, a new scheme using two laser pulses with same polarization and oblique incidence is proposed to improve the production of laser driven energetic ions based on TNSA mechanism.3D PIC simulations show that the charge of high energy ions is twice of that using only one laser when these two lasers are separated away and interacting with plasma independently. Furthermore, with these lasers close enough for optimized incidence angle and plasma density gradient, energetic ions generated becomes much more than doubled, along with small energy spread and narrow distribution both angularly and spatially.Our scheme provides a new way for generating high-charge electron and ion bunches through laser-plasma interaction.