低密度泡沫金提升黑腔腔壁再发射率的实验研究  

Experimental study on improving hohlraum wall reemission ratio by low density gold foam

作　　者：张璐[1] 董云松[1] 景龙飞[1] 林雉伟[1] 谭秀兰[1] 况龙钰[1] 黎航[1] 尚万里 张文海[1] 李志超[1] 詹夏宇[1] 袁光辉[1] 李海[1] 江少恩[1] 杨家敏[1] 丁永坤[1] 

机构地区：[1]中国工程物理研究院激光聚变研究中心,绵阳621900

出　　处：《物理学报》2016年第1期321-327,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11305158)资助的课题~~

摘　　要：提高黑腔辐射温度对高能量密度物理研究,尤其是惯性约束聚变研究至关重要.提高黑腔腔壁再发射率是增强黑腔辐射温度的一个有效措施.理论研究发现低密度泡沫材料能够降低腔壁能量损失,进而提高再发射率.在神光II原型激光装置上开展了泡沫金和固体金再发射能流对比测量实验,证实了该理论研究.实验利用透射光栅得到具有空间分辨和谱分辨的X射线发射,测量结果表明在190 eV的黑腔辐射场作用下,0.4 g/cc密度的泡沫金可比固体金提升约20%的X射线能流发射,并且增加的发射以1 keV以下的低能能段为主.自相似解得到的理论结果和MULTI 1D模拟计算的结果均表明泡沫金可提高腔壁再发射能流,与实验结果定性一致.研究结果表明,泡沫金作为黑腔腔壁材料可提高腔壁再发射率,增强黑腔辐射温度,具有诱人的应用前景.It is important to improve the hohlraum radiation temperature for the research of high energy density physics,especially for study of inertial confinement fusion. Increasing the wall reemission ratio is an effective way to improve the temperature. It is found in theory that low density foam could reduce hohlraum wall energy loss, and then increase hohlraum temperature. In previous studies, experiments have shown that laser-to-X-ray conversion is enhanced by Au foam. However, improving reemission ratio is more important to increase hohlraum radiation temperature, because most of energy is lost in the wall.In this paper, we report our experiments carried out on SGIII prototype to compare the X-ray flux reemitted by Au foam and that by Au. For the experimental design, Au solid and Au foam are irradiated symmetrically along the axis by hohlraum radiation source Tr（t）, which is assessed by broadband X-ray spectrometer flat-response X-ray diodes.The measured peak temperature is about 190 eV. Reemission flux from sample is measured by transmission grating spectrometer（TGS）. The space-resolved image for pure Au sample shows that the hohlraum radiation is asymmetrical along the axis in the experimental conditions, temperature of top is higher than that at the bottom, which is consistent with simulation results obtained by using IRAD3 D code. In order to compare the reemission flux from Au solid sample and that from Au foam sample in same conditions, we need to correct the symmetry of hohlraum radiation. By multiplying the ratio of top flux to bottom flux in pure Au target by the bottom flux in Au-Au foam target, where Au foam is on, we make sure that they are ablated by the same radiation source. The calculated results show that X-ray flux is increased by 20% by Au foam of 0.4 g/cc density when the hohlraum temperature is 190 eV. The typical observed time-integrated X-ray reemission spectra for Au solid and Au foam by TGS are also shown. We see that N-band and O-band reemission are clearly enhanced by Au foam, and

关 键 词：再发射率 金泡沫 黑腔 辐射烧蚀 

分 类 号：TL632[核科学技术—核技术及应用]