基于受激布里渊散射能量转移的冲击点火激光技术研究

提出一种新型的激光放大技术, 高效地实现冲击点火所需的10² ps级高功率激光脉冲. 该技术耦合了传统的激光驱动器放大技术和受激布里渊散射(SBS) 脉冲压缩技术, 在不改变现有激光装置主体结构的前提下, 使用长脉冲(数 ns) 充分提取主放大器储能, 然后在系统输出端通过SBS进行脉冲自抽运的能量转移, 将长脉冲能量转移给10² ps级的冲击脉冲, 实现高效放大的目的. 该技术在主动控制下实现能量转移, 将克服传统SBS压缩时间特性不可控的缺点, 输出满足冲击点火时域特性要求的精密控制激光脉冲.

Study on stimulated Brillouin scatting energy transfer to amplify laser pulses for shock ignition in laser fusion facilities

Shock ignition is considered as a relatively robust way to achieve the efficient fuel burn in inertial confinement fusion.However it requires intense laser pulses of sub-ns to launch strong convergent shock to ignite the pre-compressed target.Here we present a novel method,which has a substantially high extraction efficiency,to amplify laser pulses of～200 ps for shock ignition.In this method, stacking pulse with a Stokes light of～200 ps in the front and a pump light of～5 ns following,is employed to propagate in the amplifier to extract the stored energy,then in the final system after harmonic conversion,laser energy is transferred from pump pulse to probe pulse by stimulated Brillouin scattering.Because of employing long pulse in the main amplifier,an output laser energy of 15—20 kJ is achievable at fundamental frequency.Simulations show that the energy transfer efficiency is up to 75%,considering harmonic conversion efficiency of 60%—80%,implying that 5—10 kJ laser pulses of～200 ps can be produced using this scheme.As a result, only～20 beams are required to generate the ignitor,reducing the cost for realizing the shock ignition.