强激光驱动下的重离子加速主要物理过程研究

The laser driven ion acceleration study has become a high-light research field of high energy density physics, due to its broad fundamental applications. The present study almost focus on laser proton accelerations, but, there are seldom studies on laser driven heavy ion accelerations. Compared with laser driven proton accelerations, the heavy ions are also of significant applications, such as heavy ion oncology, heavy ion fast ignition. Due to the higher Coulomb force, its applications also include the physical study of quantum electrodynamics. Furthermore, people can also create the states of quark gulon plasmas, by the collisions of high energetic heavy ion beams. However, it is more difficult than laser driven proton acceleration to study laser driven heavy ion accelerations: a) When there exists both heavy ions and protons, due to its relatively small charge-to-mass ratio (q/m), heavy ion can not be accelerated efficiently. b) All kind of atomic process (ionization physics and Bremsstrahlung radiation) , which can significantly affect the laser plasma interaction process, need to be taken into consideration. Through this project, we shall systematically study the basic physical process in the laser driven heavy ion accelerations, and establish the basic physical process model and computer simulation framework.

激光驱动下的离子加速研究因其广泛的基础应用已经发展成为高能量密度物理领域的热点研究方向。然而目前的研究大都集中在激光轻质离子（质子）加速，激光驱动下的重离子加速却鲜有研究。相比与高品质质子束，高品质重离子束同样具有非常广阔的应用，比如重离子肿瘤治疗，重离子快点火等。此外，由于重离子的高Z特点，还可以用来研究量子电动力学的相关物理过程。通过高能量的重离子间的对撞，还可以用来研究夸克胶子等离子体。相比于激光质子加速，激光驱动下重离子加速则要困难的多，主要体现在：（一）当同时存在重离子，以及质子等轻质离子时，重离子由于其较小的荷质比而无法获得优先加速。（二）各种原子物理过程（电离物理，韧制辐射物理）会影响着激光等离子体相互作用过程，需要予以考虑。本课题将对超短超强激光与重元素等离子体相互作用中离子加速问题作深入的研究，建立比较完整的物理过程模型以及对应的计算机模拟框架。

基于该项目的强激光驱动重离子加速主要物理过程研究因涉及到非常复杂的原子物理过程，在该项目的资助下，我们开发了电离模型，碰撞模型，以及韧致辐射模型，并植入了PIC程序。2019年，国际上使用最广泛的激光与等离子体相互作用数值模拟软件EPOCH―由英国华威大学一个专门的研究团队负责开发和维护的开源软件―在发布的新版本中，韧致辐射模块即采用了我们所发展的数值模拟技术。利用该数值模拟程序，我们系统地研究了强激光驱动重离子加速，并与实验结果进行校验。该研究具有重要的科学意义，此外该研究还是许多重要的工程应用的物理基础，这些应用包含：快点火惯性约束核聚变，激光驱动强流带电粒子源，伦琴和伽马射线源以及太赫兹源等。