定向红外条件下光纤布置形式及光源参数对低温靶温度场的影响  

Influence of directional infrared irradiations on the temperature field in ICF cryotargets

作　　者：郭富城 李翠[1] 厉彦忠[1] Guo Fu-Cheng;Li Cui;Li Yan-Zhong(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,西安710049

出　　处：《物理学报》2021年第16期35-46,共12页Acta Physica Sinica

基　　金：国家重大专项(批准号:***040301.2);国家自然科学基金面上项目(批准号:52176021)。

摘　　要：惯性约束核聚变成功的关键之一在于靶丸内要形成均匀的燃料冰层,靶丸外表面温度特性对惯性约束聚变低温靶内形成均匀的燃料冰层有着决定性的影响.为使得靶丸外表面温度场尽可能均匀,需采用定向红外的方式对靶丸外表面温度进行局部调控.采用全三维低温靶物理模型,建立定向红外光路追踪与温度场计算耦合计算的光热耦合数值模型,研究了定向红外条件下光纤布置形式及光源参数对低温靶温度场的影响规律.结果表明:在光纤总功率不变的前提下,光纤数量越多,靶丸外表面温度场均匀性越好.光纤数量小于等于2时,靶丸外表面温度场无法得到明显改善;光纤数量大于2时,靶丸外表面最大温差和加权温差降低幅值极限为61.94%和76.33%.光纤投射的光斑向南北两极适量偏移可以改善靶丸外表面温度场均匀性,其他的偏移方式会恶化温度场均匀性.For an inertial-confinement-fusion cryogenic target,the fusion ice layer inside the capsule should have a uniformity more than 99%and an inner surface roughness less than 1μm(root mean square)to avoid RayleighTaylor instabilities.And this highly smooth ice layer required for ignition is generated at the presence of volumetric heat and affected by the thermal environment around the capsule.For the D2 fuel targets,the volumetrically heating can be supplied by exposing the ice layer to IR radiation.A major challenge of IRlayering is a spherically uniform IR illumination of the capsule,particularly for capsules held in cylindrical hohlraums in indirect-drive targets.In the present study,a numerical study is conducted on the thermal environment of D2 fuel capsule under directional infrared radiation.A 3D simulation model coupling the photonic and thermal fields has been established based on the Monte Carlo ray tracing method.The influence of infrared optical fibers’layouts and source power intensity on temperature characteristics outside the capsule have been studied.The results indicate that at constant total power of optical fibers,the more optical fibers set up,the lower the average temperature of the outer surface decreases,and the more uniform the capsule outer surface temperature turns to be.The temperature uniformity of capsule outer surface deteriorates with the two or less optical fibers,but improves with the number greater than 2 in which case DTmax and DTw can decrease by 61.94%and 76.33%at most.A proper offset of optical fiber spots towards the hohlraum poles can improve the temperature uniformity of capsule outer surface,while the other two optical fiber spot offset schemes deteriorate the temperature uniformity.The results are of guiding significance for determining the optical fibers layout in experiment and further design option for cryogenic targets.

关 键 词：惯性约束核聚变 低温靶 定向红外 光热耦合 数值模拟 

分 类 号：TL61[核科学技术—核技术及应用]