Investigation On Time-domain Properties Of Hundreds Picoseconds Pulse Based On SBS Pulse Amplification

Shock-ignition scheme is a new kind of inertial confinement fusion ignition way. Itrequires the laser pulse width is200ps, the laser pulse energy is kilojoules and the peakpower is dozens of TW. The traditional MOPA and CPA can not achieve efficient highpower picoseconds pulse amplification. Stimulate Brillouin Scattering (SBS) cancompress pulse, and amplify laser pulse of hundreds picoseconds, which can obtain highpower laser. The technology is not needed to improve the laser device, and the structureis simple. We mainly study on the factors which have effect on the stability in SBSpulse compression, which can improve stable seed pulse in SBS amplification. At thesame time, we have researched on time domain feature in SBS amplification.Firstly, we analyze the process of Stokes production. Starting from Maxwellequation, we analyze SBS equation in SBS amplification. This is useful for the nextwork.Secondly, based on super transient model we numerically simulate the SBSamplification, using Fortran software, and debate some factors affecting time domainfeature of Stokes such as pump parameter, seed parameter, construct parameter and soon. From the result, we can see these factors affect the time domain feature of Stokesvastly. We find the rule and analyze the reason.Finally, in experiment, with FC-70, FC-40for SBS medium, using double-cellstructure, we study the pump parameter, construct parameter and medium parameteraffect the Stokes pulse width and energy under the condition that the pump energy isunder200mJ, pump pulse width is8ns, and the pump wavelength is532nm. We analyzethe condition that we can product the stable Stokes. So we can apply it for SBSamplification. The experiment indicate that under200mJ, FC-70can generate morestable pulse than FC-40for its weak gain.But FC-40can generate more narrow pulsewidth, because our energy is low. The narrowest Stokes pulse width of FC-40is102ps.At the same time, improving medium fluidity, filtering the medium and keeping thetemperature can improve the pulse width stability mostly.In SBS amplification, using FC-40for SBS medium, we study pump energy, seedenergy and delay time affect the Stokes, with the pump wavelength of532nm. Weanalyze the reason. Comparing with the theoretical simulation, we found somedifference between experiment and theory, and analyze the reason. In the experiment,we obtain the most energy amplification is10.1; the most energy extraction energy is39.6%. Finally, we come up with the conditions that export the200ps Stokes.