【作者】 吴军；

【导师】 杨向东；

【作者基本信息】 四川大学 ， 原子与分子物理， 2002， 硕士

【摘要】 自从高能短脉冲激光被很好地应用以来，人们对激光作用在物质上所产生的高密度热等离子体表现出了强烈的兴趣。尽管激光等离子体尺寸极小(～100μm)寿命短且参数以几百皮秒的量级变化，但却有相当重要的科学和实际作用。激光等离子体释放出大量的X射线，因此对X射线进行摄谱分析是一种重要的诊断方法。由于激光等离子体变化快，且其X射线辐射的时间特性包含有丰富的物理信息，因此时间分辨的X射线辐射特性诊断是研究激光等离子X射线辐射随时间的演变，各种动力学过程和辐射输运等物理问题所必需的关键诊断技术。自从六十年代末到七十年代初以来，应激光聚变实验研究的需要，软X光时间分辨诊断技术有了长足的发展，摄谱装置由以前的Dante谱仪到现在的软X光条线相机，(△t～20ps)，通过这些装置，可以有机会验证诸多等离子体现象。测量激光聚变靶产生的软X射线时间变化连续谱的形状，可以知道许多X射线产生过程的详细动态记录，这有助于理解实验的热学条件。观察轨迹特征谱线的闭合序列，能提供关于激光等离子体激发能量和滞后能量的传输过程记录。精细光谱特色的时间分辨(如线宽，线形)还可提供靶压缩等动态过程中的信息。 目前通常采用透射光栅与条纹相机耦合的方式作为X射线谱仪。其测得的软X射线连续谱有较好的时间分辨率(△t～20ps)和适当的空间分辨率(△λ≥1)。并且这套谱仪适用的能谱范围广(0.1—10keV)，敏感度高，有记录大量信息的能力。谱仪所取的图形记录是波长与时间的二维图像，虽然此记录包含了所有关于软X射线的必要物理信息，但信息却与谱仪的响应细节特征有重叠效应，这就使获取信息的准确度下降，为此，解谱工作就显得很重要，必须 四川大学硕士研究生毕业论文对测量结果进行回椎、展开，迭代处理，从中求出真实的互光能谱。 在 200神光＊磨合实验中，使用一个 X射线透射光栅Q000L／mm）和一个软 X射线条纹相机作为 X射线谱仪。测得能谱的时间分辨率 6 t～20ps。由 ＿，、＿．＿，＿。＾…。。＿＿、。，，、A几 l＿＿，、一、…、＿＿＿条纹相机输出分布函数IO＊＝字－ZS（mSO）q／me＊a加m＊（详见正 人（D十 L）“脑扬”文）出发，通过迭代回推等数学方法，再经过误差校正，成功解出了二射线的源光谱。更多还原

【Abstract】 Since the introduction of high-power short-pluse lasers well, there has developed a strong interest in the high-density high-temperature plasmas produced by the interaction of intense laser light with matter. Despite these laser-produced plasmas are small-size(~100urn)and short-lived, with parameters changing on the scale of tens to hundreds of picoseconds, they have quite important science and practical effect. Measuring X-ray energy-spectrum emitted by these laser-produced plasmas is a important diagnose method, because they emit a mass of X-ray. Now the method has application at large. Because the laser-produced plasmas are rapidly varying, temporal resolution of spectral features is important to investigation of X-ray radiancy evolvement with time, many dynamic plasma processes and radiation transport. Soft X-ray time-resolved diagnosis technology have had quiet great progress since from sixty’ s end to seventy’ s early. Take a photograph of devices hav developed from Dante spectrometer to soft X-ray streak camera(At~20ps) in which one has a chance to investigate a good many plasma phenomenon. Measurement of the time-varying spectral shape of the soft X-ray continuum from laser-fusion targets can provide a detailed dynamical record of X-ray processes important to the understanding of thermal conditions in such experiments. Observation of the on-off sequencing of characteristic spectral lines from tracer materials arranged in layers in, or surface patterns on, planar or spherical targets can provide a record of radial or lateral energy transport processes in laser-generated plasmas. In addition, the temporal evolution of detailed spectral feature (such as linewidthand line shape)can provide important information about ablation dynamics and perhaps target compression in laser-fusion studies.Now a very interesting time-resolved X-ray spectrometer, in which an transmission grating is coupled with a X-ray streak camera has been a X-ray spectrograph. The device has excellent spectral (??1 ) and temporal (?t~20ps). And it has a wide spectral range(0.1 ?10keV), high sensitivity and a large information recording capacity. The photographic data record of the transmission grating spectrometer is a 2-D representation of X-ray spectrum (wave length vs time). Although the data record contains all the essential information about the desired source spectrum, that information is folded together with details of the instrument response. So one must carry thought unfolded work.Using transmission grating spectrometer to measure soft X-ray in 2001sheng-guangII experiment. Time-resolved spectrum has temporal resolution ?t~20ps. In (the streak cameraoutput distribution function, see text), we have unfolded successfully the X-raysource spectrum with repeatedly et al mathematics way.更多还原