Name: applying x-ray imaging crystal spectroscopy for use as a high temperature plasma diagnostic
Uploaded: 2016-08-25T13:00:00.000+00:00
Duration: 6 min 46 s
Description: Watch this Scientific Journal Video about Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic at JoVE.com

The authors would like to thank Matt Reinke and the Alcator C-Mod team for designing, building, and testing HIREXSR. This work was supported by DOE Contract Nos. DE-FC02-99ER54512 and DE-AC02-76CH03073.

1.选择合适的谱线<ol><li>选择将决定得到的数据的质量适当的发射线。 图8示出其中的惰性气体排放线将是在用于电子温度不同的值相关的。 <ol><li>需要注意的是电离状态和行比率按电离，碰撞激发，辐射复合和介电重组的竞争来确定。这些方法可以与等离子体的温度和密度而变化。 见图9此变化的一个例子。 </li></ol></li><li>请参考波长和感兴趣的发射线相对优势等发表作品。在这个协议中，使用介质Z他一样离子作为其特征在于水稻，JE 等人 （2015年）4。参见图10中的示例频谱。 </li><li>请注意，它研究的主要系列之外的线条卫星是很重要的，因为他们共同ULD是未解决与正在测量的线。一些固有杂质（铁，钼，钛等 ），将始终从托卡马克等离子体朝向结构和组件本。例如， 图11表明氩阮文黎α1大于阮文黎α2线是更好的选择，因为后者与钼线重叠。 </li><li>对于温度范围等离子体0.5-3左右千电子伏，捕捉氩以下他般的线条（全部来自N = 2跃迁）:共振（W，1秒2 1 S 0 - 1S2P 1 P 1），禁止（Z，1秒2 1 S 0 - 1S2P 3 S 1），并互组（X，1秒2 1 S 0 - 1S2P 3 P 2和y，1秒2 1 S 0 - 1S2P 3 P 1）。氩n = 2的跃迁中，H形频谱位于3.72埃&lt;λ&lt;3.80埃，他状SPECTR之间嗯在于3.94 A &lt;λ&lt;4.00埃之间。参见图11和图12对这些光谱的曲线图。 </li></ol> 2.安装的硬件HIREXSR <ol><li>请参考有关安装和建设HIREXSR 1,2,5的细节和具体的相关发表作品。本节将集中在该过程中最重要和最关键的步骤。 </li><li>山HIREXSR上Alcator C-国防部的跑道形的港口之一，角度，允许8°非对角视图。 </li><li>得到的圆形（102）石英与4.56215二维间距，一个直径为50毫米，和曲率1385毫米半径晶体，以查看该H-像光谱。 </li><li>得到的矩形（102）与一个4.56215埃2D间距石英，64毫米的宽度和27mm的高度，以查看他状的频谱。 </li><li>插入并通过访问分光计的壳体安装HIREXSR的壳体内两个晶体位于侧面的舱口。看到它们的布局图13。 </li><li>通过相同的舱口，螺栓上在分光计体指定可动支架四个探测器，保留为H状光谱一个检测器，和其他三个为他状的频谱。这种布置在图14示出。 </li><li>安装件定位从晶体125厘米远，使得从晶体到该检测器的中心的线，使与该罗兰圆的中心到晶体的中心位置，其中θ线θB / 2的角b为被测量的光谱的中心的布拉格角。参见图5。 <ol><li>请注意，对于氩气中，H形晶体用结果θB = 55.5°，并且他状晶体用结果θB = 60.5°。 </li></ol></li><li>角度探测器匹配改性装置如图5所示。 <ol><li>注意，该检测器的精确对准不是重要的，因为所收集的数据将针对一个已知源实验运行过程中进行校准。 </li></ol></li><li>通过安装0.001"厚，4"直径的铍窗从托卡马克真空独立HIREXSR的氦气氛。看到它的布局图13。 </li><li>安装窗口和反应器之间的10"闸阀，以防止铍窗口的故障。 <ol><li>注意，当局部压力上升超过10毫托，以避免光谱仪和托卡马克都损坏闸阀应该关闭。 </li></ol></li><li>参考图6和图15为顶向下视图和侧视图，分别HIREXSR和Alcator C-国防部的，具有检测器和晶体的相对距离沿，并且光谱仪和托卡马克之间。 </li></ol><ol><li>指用于在激光吹断装置10的结构的细节和具体的相关发表作品。 </li><li>注入钙，采取与100埃的铬（以在该材料的激光吸收，以帮助）2微米的CaF 2滑动，并放置在激光吹断系统的幻灯片。因为这需要前往C-MOD反应器，做到这一点的操作开始的前一天。 </li><li>切换到通道14 Alcator C-国防部的闭路有线电视系统上查看黑白CCD摄像头，手表的幻灯片。 633纳米激光二极管点应该是在幻灯片上可见。 </li></ol> 4.运行等离子实验<ol><li>在运行一天的开始，开始将收集并保存从X射线计数像素探测器数据对每个实验运行，或"枪毙"的剧本。这将取决于在PLAC特定检测器的设置即具体到HIREXSR的步骤这里提出。 <ol><li>从在C-MOD控制室工作站，打开命令行终端。 </li><li>远程输入"的ssh -X DET @ dec0xx"，其中xx从07-10不等连接到探测器。 </li><li>通过输入"CD p2_1mod"更改目录</li><li>运行命令"runtvx"。这将弹出一个窗口，将文本雪崩。 </li><li>一旦停止文本，按回车键两次。启动脚本将帧速率设置为50赫兹和阈值能量〜2千电子伏。文本的另一个雪崩都会发生，探测器将开始校准。 </li><li>等到这一切结束，在窗口中输入"退出"。 </li><li>重复每个探测器07-10。 </li></ol></li><li>全天，通过连续地泵送气体进入壳体的操作的持续时间保持在略高于环境温度在HIREXSR氦气氛。这减少了大气X射线ATTENuation和晶体的热膨胀。 </li><li>与现场工程人员合作，以确保血浆即将拍摄时达到所需等离子体参数。如果参数从出手就出手改变，传达给每个镜头之间的工程技术人员。 <ol><li>此外，在运行日的某个时候，请向工程人员"锁定模式"打一枪换当天获取的数据进行校准。为锁定模式的说明，以及它们如何被用于校准见莱因克等人2012年1。 </li></ol></li><li>对微扰运输研究:每次拍摄，程序激光吹断系统之前注入的非再循环杂质进入在期望的时间的血浆中期望的浓度（ 氟化钙，钪等 ）。 <ol><li>决定的激光光斑大小，它控制物料从滑动烧蚀量。从Alcator C-国防部，消融队友约10％的运营经验里亚尔使其进入低功耗运行10在等离子体核心。典型光斑尺寸范围从0.5至3.5毫米。 </li><li>确定所需的放空时机，牢记最大10赫兹的运行速度。 </li><li>输入所需的点尺寸和定时到激光吹离系统控制GUI。例如，通过Rice 等人2013 11运输研究变化从0.5斑点尺寸至3.5mm并有注射每300毫秒。 </li></ol></li><li>对于所有的研究:在等离子体开始后设置气体阀以粉扑氩到等离子体0.3秒。粉扑应持续约0.1秒，提高氩气密度的电子密度约10 -4倍。 </li><li>使用dwscope期间运行日使用MDSplus如C-MOD系统中，查看实时诊断数据。 <ol><li>从托卡马克控制室工作站，从应用程序菜单中打开dwscope </li><li>获取与anoth显示相关的诊断的一个或多个文件的范围呃用户，或创建使用MDSplus树命令语言（高级）定制的。 </li><li>点击"自定义|使用保存的设置从..."并选择一个范围，文件加载它。一个有用的例子范围，plasma_n_rot_z.dat，示出与图16中的dwscope GUI。 </li><li>离开文本框在底栏为空，数据将从最近的投篮被加载。 </li><li>如果需要，输入一个镜头号码，点击"应用"从一个特定的镜头加载数据。 </li></ol></li><li>通知工程运营商，所有的准备为即将到来的拍摄完成，他们可以继续点燃等离子体。 </li><li>等待操作员启动等离子体和其结束。在Alcator C-国防部，起始过程将持续约3分钟，并在等离子体会燃烧不到10秒。 <ol><li>如果使用激光放气系统，在视觉上确认经由滑动的相机视图滑动消融（参照第3节）。 </li></ol></LI&gt; <li>等待托卡马克，以便进行下一个镜头冷却。在Alcator C-国防部，这一过程将持续10-15分钟。 <ol><li>利用这个时间，使建立了实验的任何变化，并将它们传达给操作人员，所以如果需要，它们可以随后施加。 </li></ol></li><li>请注意，如果硬件的任何改变都需要，研究者应该要求"小区接入"的运营商，在此期间，他们将打开托卡马克和分离等安全功能，让人们进入Alcator C-国防部的环境。否则，不受限制地进入前和运行一天后可用。反应堆附近的工作安全帽时，应始终穿着。 </li><li>使用dwscope作为前查看任何所需的等离子体诊断运行一天后总结。 <ol><li>注意，数据也可以通过编程为不同的语言的各种MDSplus API的访问。 </li></ol></li></ol> 5.校准HIREXSR锁定模式数据使用零级命中值<ol><li>使用该HIREXSR分析代码（零级命中值）反转HIREXSR数据，这是线积分12。所有这些步骤，参考和详细的分类可以在网上未公布的零级命中值手册上的麻省理工学院等离子体科学和聚变中心（PSFC）的在线图书馆中找到。本节介绍首次设置和零级命中值的启动，其次是校准过程。 </li><li>按照Alcator C-国防部wiki页面上的说明，零级命中值设置为零级命中值连接到网络PSFC的机器上首次使用。您可能还需要从网络管理员要求的光谱树的写权限。 </li><li>输入"IDL"到命令行从启动IDL命令行界面。 </li><li>从IDL，输入"@ thaco.bat"推出零级命中值。 </li><li>识别锁定模式被用于该数据的校准。 <ol><li>打开Web浏览器并导航到PSFC日志。 </li><li>点击＆＃34;自定义查询"按钮，弹出一个搜索页面。 </li><li>在自定义查询文本框中，输入"SHOT LIKE&#39;1yymmdd %%%"和TEXT LIKE&#39;％锁定模式％&#39;"，其中yymmdd是运行日的年/月/日，以弹出包含文本已锁定日志条目模式。 </li><li>确定从日志条目锁定模式的出手次数，并注意锁定模式的开始/结束时间。 </li><li>注意，具有锁定模式基线不是严格必需的所有诊断，如那些涉及线比率一样确定电子温度13，但强烈建议以来的布拉格角度可以从每天由于晶格移位膨胀/收缩14 。 </li></ol></li><li>在零级命中值GUI，输入出手数文本域"（ACTIVE）SHOT"锁定模式，然后按回车。 </li><li>按下按钮"LAUNCH W_HIREXSR_CALIB"，并启动校准部件。 <ol><li>在窗口第在弹出，确保标有"SHOT"字段包含锁定模式下拍摄的数量，并记数的"模块"。之后的任何更改都到任何领域取得按Enter键。 </li><li>点击"LOAD"按钮，在窗口的顶部第三和等待要加载的数据。 </li><li>在窗口的中间三分之一点击"LOAD"，等待要加载更多的数据。 </li><li>如果数据成功加载和配合椭圆形好看，重复的"模块"字段（1-4）用不同数量的校准步骤，因为锁定模式下拍摄已经校准。 </li><li>如果所有模块（1-4）已经被校准，跳过因为拍摄的已校准的校准和检测器对准其余步骤，并直接转到第6章。 </li></ol></li><li>通过选择窗口的上部，右上角相应的选项开始光谱拟合。只有H-喜欢和他一样Ar和钙光谱的重新目前支持开箱即用。 <ol><li>设置"T1 ="和"T2 ="字段分别锁定模式开始/结束时间被在日志中提及。 </li><li>移动"FIT低"和"FIT HIGH"滑块直到合适的区域中，通过在左上角，仅包含其中感兴趣的光谱线是明显解决该区域上叠加频谱虚线白线表示。 </li><li>点击"F​​IT /光谱保存"按钮，等待拟合过程来完成。 </li><li>一旦拟合过程结束后，所使用的"规格"滑块或左/右箭头旁边在GUI的中间三分之一到视觉检查所有的光谱拟合。 </li><li>删除任何不良或异常检查旁边的"SPEC"滑块"BAD"复选框适合。参考步骤1.3发现已知结构的谱比较的作品。例如，他般的钙光谱将类似于图10。 </li&gt; </ol></li><li>首先通过选择GUI底部的三分之一所需的行（W，X，Y，Z）椭圆拟合。 <ol><li>点击"F​​IT椭圆"按钮，等待椭圆是适合的光谱适合。 </li><li>移动"低"，"高"和"OUTL"滑块，直到椭圆适应视觉光谱匹配。椭圆是适合用非线性最小二乘法MPFIT 15，它可以是挑剔。 </li><li>完成后点击"保存椭圆"按钮，并与下一个期望的行重复这个过程。 </li><li>当所有的线路已经适应，"模块"更改为尚未校准，然后按回车不同的模块（1-4），并从步骤5.7.1再次进行。 </li><li>当所有的模块都被校准，点击"退出"按钮（不是"X"）关闭小部件。 </li></ol></li><li>按下按钮"LAUNCH W_HIREXSR_DET_ALIGN"，启动探测器对准部件。 &lt;OL&gt; <li>在"SHOT"字段中输入已经被校准，然后按回车最近的已知锁定模式的拍摄数量。记下"模块"领域。 </li><li>点击"LOAD"按钮，并等待数据加载。 </li><li>在左下角，写下所有的滑块值中的"检测器位置"面板。 </li><li>在"SHOT"字段中输入被校准锁定模式的拍摄数量，然后按Enter。 </li><li>点击"LOAD"按钮，并等待数据加载。 </li><li>输入值写下来更早进入"式检测器位置"面板中，按每次更改后进入。 </li><li>更改值在"探测器位置"面板中，或者通过滑块或在文本框中手动更改值，直到全部或大部分圆形残差躺在绿色的酒吧内。 </li><li> "模块"字段更改为尚未对准一个模块（1-4）和PRESS进入。然后从步骤5.10.1进行。 </li><li>当所有的模块已经对准，点击"退出"按钮（不是"X"）关闭小部件。 </li><li>校准现在完成的;继续与锁定模式下拍摄的第6部分。 </li></ol></li></ol> HIREXSR数据使用零级命中值6.高级分析<ol><li>使用该HIREXSR分析代码（零级命中值）反转HIREXSR数据，这是线积分11。所有这些步骤，参考和详细的分类可以在网上未公布的零级命中值手册上的麻省理工学院等离子体科学和聚变中心（PSFC）的在线图书馆中找到。本节涵盖的实际反演过程，查看配置文件数据。 </li><li>确定感兴趣的投篮出手数。 </li><li>从零级命中值GUI中，场"（活动）SHOT"设置为拍摄数量，然后按回车。图形用户界面应该承认日志上底部的变化。 </li><li>选择感兴趣的谱线，设置字段:＃34; LINE"到感兴趣的行号为氩气，这通常是2为他状Ž线，以及3为H状lya1线。 <ol><li>点击"LIST零级命中值行号"列出所有的行号可供选择。 </li></ol></li><li>在GUI的顶部点击"分档"选项卡上。 <ol><li>点击"检查THT可用性"检查零级命中值树（THT）的可用性。图形用户界面的底部应该记录所有可用零级命中值树。 </li><li>设置字段"新零级命中值树（THT）号"中的可用性不列出的第一个号码。 </li><li>点击"创建"按钮，创建一个新的THT所以前面的分析不会被覆盖。 </li><li>点击"检查THT可用性"再度刷新可用THTs的列表。 </li><li>在"THT"字段更改旁边的"（活动）SHOT"场到新创建的THT号码，然后按回车。该GUI日志应该承认这个动作。 </li></ol></li><li>若t他目前的投篮不是锁定模式下，单击GUI的顶部的"CALIB"选项卡。 <ol><li>改变"校准数据从摄影"到锁定模式被用于校准的数据。 </li><li>按下"复印"按钮在校准复制。 </li></ol></li><li>再次单击"分档"选项卡。 <ol><li>咨询零级命中值手册上制作自binnings说明。 </li><li>要复制从前面的分析分档，进入拍摄/ THT到各自的领域（按每次更改后进入）在面板中的"复制"按钮。 </li><li>复制在分档:选择"分支A"，然后单击"复制"，然后选择"分支B"，再次单击"复制"。 </li></ol></li><li>点击界面的顶部的"配置文件"选项卡。 <ol><li>咨询零级命中值手册，了解有关如何使用出现在本节中的高级功能的说明。 </li><li>否则，进入拍摄/ THT往返马前面分析到各自的领域在顶部面板（按每次更改后进入）。 </li><li>点击"LOAD RHO"按钮，接着"LOAD GOOD"按钮。 </li></ol></li><li>点击"Run零级命中值"按钮，将零级命中值开始反演过程。这可能需要几分钟时间。 </li><li>注意，零级命中值实际上是通过一系列的独立的步骤在此过程中要:对光谱以计算各行的时刻运行多高斯拟合，使用这样的时刻来计算线积分信息数据，然后翻转该线集成数据通过最小二乘法。从这些步骤中间产出，有利于故障诊断，可以在瞬间被发现和型材部件。感兴趣的用户被鼓励通过零级命中值手册，以寻找有关这些步骤以及如何使用这些小部件用于在反演过程更细粒度控制的更多信息。 </li><li>一旦反演过程菲尼畲族，从"配置文件"选项卡中单击"LAUNCH_W_HIREXSR_PROFILES"，以目视检查的配置文件。 <ol><li>按"Load"按钮，在下方的"树I / O"面板，等待数据加载。 </li><li>如果自动过程失败，找到"DO FOR序现象"，并点击"全部"来快速重做所有的倒置。 </li><li>通过使用"时间"滑块底部改变帧手工检查右侧的反转轮廓。 </li><li>如果有，似乎是错误的（ 例如，负温度，向边缘等非物理渐变），可以使用任何倒型材-旁边的"CH＃"/ +键选择左侧离群渠道，并取消了"GOOD"选项，从反转的步骤删除它们。 <ol><li>需要注意的是排放量往往是向边缘弱所以不确定性较高;然而，倒立温度还是应该去小（不一​​定）z在边缘主任值。 </li></ol></li><li>找到"DO FOR易序"，然后单击"CURRENT"反转当前帧的配置文件。重复删除异常值，直到倒轮廓似乎是正确的。 </li><li>按"保存"的数据似乎满意的售后服务。 </li><li>使用配置文件小部件检查数据。 </li></ol></li><li>如果需要，点击"LAUNCH W_HIREXSR_COMPARE"中的"比较"标签，比较不同的光谱线构造轮廓。一个常见的​​场景，这是非常有用的是，当等离子核心温度变得足够热氩H-般涌出来超越他般涌出。 </li><li>注意，数据也可以通过编程为不同的语言的各种MDSplus API的访问。参考零级命中值手册的相关路径。 </li></ol>

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The authors have nothing to disclose.

通过这种技术产生的数据可以在多种实验性研究中使用。离子温度和环形速度分布可以在宽范围内运输的研究，包括内在自生等离子体旋转和非本地微扰效应的使用。通过激光吹离测量的注入的杂质的光谱还可以提供有关的杂质的等离子体中的传输的重要信息，如在Howard 等人。2011年10月进行。此时，从等离子体芯1没有其它等离子体的诊断可以提供时间和空间分辨的离子分?...

X射线谱提供了丰富的高温等离子体的信息;例如电子温度和密度可以从线的强度比来推断。通过使用约翰分光计观看等离子体离轴，有可能构造的等离子体参数，如密度，温度和速度与良好的空间和时间分辨率1,2-等离子体内部型材。这份手稿展示了高分辨率X射线晶体成像光谱仪与空间分辨率（HIREXSR），高波长分辨率成像空间用于查看中原子序数元素的氢和氦样离子托卡马克X射线光谱仪的操作等离子体。 HIREXSR部署在Alcator C-国防部，分别为0.67米和0.22米的主要和次要半径的托卡马克核聚变装置。它通常用氘等离子体持久0.2-8.0之间的10×20 M〜2秒，平均密度运行-3 </su1-9千电子伏3之间p&gt;和中心电子温度。在这些条件下，介质给Z高杂质元素变得高度离子化，并在X射线范围内，这HIREXSR措施辐射。基准从良好的诊断实验室等离子体得到的X射线谱的原子代码建模是很重要的证明使用这样的光谱，以确定血浆参数时等独立的诊断不可4。 每个光谱仪是专为其所需的用途。因此，有关机器及其相关概念的一般描述是必要的充分理解这些强大的工具5。当光子反射离开晶体的相邻层，并行驶的距离，该距离是其波长的倍数发生布拉格反射。 图1描述了这一现象。这个条件由等式为nλ= 2 天罪θb，其中n是重的顺序表示屈曲，λ是光子的波长，d是晶体和θB的相邻层之间的间隔的布拉格角。一个一至λ和θB之间一一对应表明在用相同的波长的检测器平面行进的特定点的所有光子。在实践中，然而，吸收和精度的限制表现为从布拉格角的偏离。这导致只有一个很小的范围内产生显著建设性干扰，由一个摇摆曲线6表示角度的; 图2为方解石晶体的一例的曲线。 HIREXSR是约翰光谱仪具有球面弯晶7。描述这种装置的前，更简单的，圆形分光计的讨论是适当的。这套了由弯晶反映入射光子在各自的布拉格角至病房单X射线光子计数像素探测器阵列。晶体和检测器铺相切的罗兰圆，如显示图3。该罗兰圆的直径等于晶体的曲率半径。所有从在圆周上，以在晶体的任何点的给定点射线具有相对于晶体本身相同的入射角。 。在图4中示出的HIREXSR，在子午平面上的球面弯曲晶体许可证的空间分辨率的情况下，子午焦点f m被定义为:F M = R C罪θb，其中R c ​​为曲率半径晶体。矢状焦点f s被定义为:F S = - F M / COS 2θB。分光计Δx的空间分辨率中给出通过: <img alt="方程" src="/files/ftp_upload/54408/54408eq_DELTA_x.jpg" /> ，其中L p是晶体和等离子体之间的距离，以及d是晶体的高度。由于晶体层的2维间隔是离散的，这必须在选择材料时必须考虑。由于检测器表面是平面的，它们只能是相切的罗兰圆在一个点，这因此产生了错误，因为所检测的光线不上的罗兰圆的对应点精确地着陆。物理上，此不对中表现为一个检测器上的特定能量的光子的"拖尾"。此约翰误差定义为<img alt="方程" src="/files/ftp_upload/54408/54408eq_delta_xj.jpg" /> ，其中l是晶体的宽度。如果检测器像素宽度ΔXp比约翰误差大得多，那么光谱分辨率是独立的它。如果他们一重可比大小的，则总误差可通过近似<img alt="方程" src="/files/ftp_upload/54408/54408eq_delta_x_2.jpg" /> 。晶体分光计的分辨能力为: <img alt="方程" src="/files/ftp_upload/54408/54408eq_lambda0.jpg" /> ，其中<img alt="方程" src="/files/ftp_upload/54408/54408eq_delta_theta.jpg" /> 。代替将所述检测器相切的点上的罗兰圆然而，在HIREXSR的检测器被稍微倾斜，以牺牲精度的光谱范围内， 如图5所示。该错误分析已经实验验证，符合期望8。 有设计约翰光谱仪时，需要考虑两个关键参数。首先，在成像范围决定什么分光计将被观察。为了研究等离子体，这是非常可取的，以查看其整个横截面，以便引起极向和toroi线转移来区分DAL转动。 HIREXSR被安装成使得它可以查看整个等离子体，并通过~8°（ 图6中示出）是离轴稍微倾斜，以允许精确环形测量。第二，时间分辨率调节，该光谱仪可以记录事件之间的最小时间。对于Alcator C-国防部，理想值低于20毫秒，比能量和粒子约束时间较短。该HIREXSR用途可以支持的6时间分辨率为20msec或更大的X射线计数像素探测器9， 表1总结了所有模块规范。 对于等离子微扰研究，激光吹除系统上Alcator C-国防部用于精确计时10提供多种消融。激光是钕:YAG（掺钕钇铝石榴石）以高达10赫兹操作。激光入射到远程控制光学列车如图7，重点和阉牛光束到幻灯片上的所需位置。激光的光斑尺寸需要被控制，以便在注射不会中断等离子体。长焦距（1146毫米）会聚透镜经由远程控制的线性阶段沿着光轴被翻译，以允许消融光斑尺寸，以改变从〜0.5至7毫米。快速光束转向经由2D压电镜来实现的。该压电系统被安装到一个RS232驱动镜安装能干。除了Nd:YAG激光器，一个633nm的二极管激光器，用于指示主（IR）光束的位置。光束是由通过第一反射镜被共线。

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applying x-ray imaging crystal spectroscopy for use as a high temperature plasma diagnostic

X射线谱提供了丰富的高温等离子体的信息;例如电子温度和密度可以从线的强度比来推断。通过使用约翰分光计观看等离子体，有可能构造的等离子体参数，如密度，温度和速度与良好的空间和时间分辨率的配置文件。然而，从基准以及诊断的实验室获得的等离子体的X射线光谱的原子代码建模是很重要的理由使用这种光谱测定血浆参数时，其他独立的诊断不可用。这份手稿展示了高分辨率X射线晶体成像光谱仪与空间分辨率（HIREXSR），高波长分辨率成像空间用于查看中原子序数元素的氢和氦样离子托卡马克X射线光谱仪的操作等离子体。此外，该手稿涵盖了激光吹气系统，可以推出这样的离子用精确定时的等离子体，以允许等离子体中运输的微扰研究。

从对他状氩光谱一次bin中的像素检测的代表性数据样本，如图17所示。该光谱线，弯曲成球状晶体的椭圆形状，都清晰可见。顶部检测器具有破碎检测器面板，并有分散在所有检测器的一些坏点。从破碎的检测器面板的数据应该被忽略。从示出所测量的光谱和由零级命中值在单个和弦进行的光谱拟合的结果的检测器片示于图18和图19，?...

Watch this Scientific Journal Video about Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic at JoVE.com

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

X射线谱提供了丰富的信息高温等离子体。这份手稿呈现高波长分辨率成像空间用于查看在托卡马克等离子体中的原子数量的元素氢和氦样离子X射线光谱仪的操作。

运用X射线成像光谱水晶的使用为高温等离子体诊断

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line ...

applying-x-ray-imaging-crystal-spectroscopy-for-use-as-high

Research

JoVE Journal

Engineering

11.3K 次观看.  Massachusetts Institute of Technology.  X射线谱提供了丰富的信息高温等离子体。这份手稿呈现高波长分辨率成像空间用于查看在托卡马克等离子体中的原子数量的元素氢和氦样离子X射线光谱仪的操作。 

视频: Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11.
Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps).
Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators.

An experimental method to examine the early plasma evolution induced by ultrashort laser pulses is described. Using this method, high quality images of early plasma are obtained with high temporal and spatial resolutions. A novel integrated atomistic model is used to simulate and explain the mechanisms of early plasma.

超短激光脉冲诱导的等离子体演化早期的调查

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a ...

科研

工程学

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

在极低的温度下角分辨光电子能谱

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

在极端的压力和温度的合成和Microdiffraction

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators &#8212; a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes.

This movie shows how an atmospheric plasma torch can be ignited by microwaves with no additional igniters and provides a stable and continuous plasma operation suitable for plenty of applications.

如何点燃常压微波等离子体炬没有任何额外的点火器

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

烧蚀材料在试验过程中等离子体发生器发射光谱边界层研究

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient optical micro-imaging technique which can be used to map and quantify such behavior. Europium thenoyltrifluoroacetonate (EuTFC) has a 612 nm luminescence line whose activation efficiency drops strongly with increasing temperature, due to T-dependent interactions between the Eu3+ ion and the organic chelating compound. This material may be readily coated on to a sample surface by thermal sublimation in vacuum. When the coating is excited with ultraviolet light (337 nm) an optical micro-image of the 612 nm luminescent response can be converted directly into a map of the sample surface temperature. This technique offers spatial resolution limited only by the microscope optics (about 1 micron) and time resolution limited by the speed of the camera employed. It offers the additional advantages of only requiring comparatively simple and non-specialized equipment, and giving a quantitative probe of sample temperature.

Europium thenoyltrifluoroacetonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

高分辨率热显微成像采用铕螯合物的荧光涂料

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient ...

High Pressure Single Crystal Diffraction at PX^2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe2+0.14Fe3+0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 &#177;0.006 &#197;, b = 8.761 &#177;0.004 &#197;, c = 5.248 &#177;0.001 &#197;, &#946; = 105.06 &#177;0.03&#186;, &#945; = &#947; = 90&#186;.

In this report, we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell at the GSECARS 13-BM-C beamline at the Advanced Photon Source. ATREX and RSV programs are used to analyze the data.

高压单晶衍射PX ^ 2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the ...

化学

Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry

A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose of efficiently driving non-equilibrium chemistry is discussed. The advantage of a flowing plasma reactor is that continuous chemical processes can be driven with the flexibility of startup times in the seconds timescale. The plasma approach is generically suitable for conversion/activation of stable molecules such as CO2, N2 and CH4. Here the reduction of CO2 to CO is used as a model system: the complementary diagnostics illustrate how a baseline thermodynamic equilibrium conversion can be exceeded by the intrinsic non-equilibrium from high vibrational excitation. Laser (Rayleigh) scattering is used to measure the reactor temperature and Fourier Transform Infrared Spectroscopy (FTIR) to characterize in situ internal (vibrational) excitation as well as the effluent composition to monitor conversion and selectivity.

This article describes a flowing microwave reactor that is used to drive efficient non-equilibrium chemistry for the application of conversion/activation of stable molecules such as CO2, N2 and CH4. The goal of the procedure described here is to measure the in situ gas temperature and gas conversion.

用于高效高温化学的非平衡微波等离子体

A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose ...

An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

Non-thermal atmospheric pressure (&#39;cold&#39;) plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to plasma are still scarce. Biomedical plasma is often operated with He or Ar feed gas, and a specific interest lies in investigation of the reactive species generated by plasma with various gas admixtures (O2, N2, air, H2O vapor, etc.) Such investigations are very complex due to difficulties in controlling the ambient atmosphere in contact with the plasma effluent. In this work, we addressed common issues of &#39;high&#39; voltage kHz frequency driven plasma jet experimental studies. A reactor was developed allowing the exclusion of ambient atmosphere from the plasma-liquid system. The system thus comprised the feed gas with admixtures and the components of the liquid sample. This controlled atmosphere allowed the investigation of the source of the reactive oxygen species induced in aqueous solutions by He-water vapor plasma. The use of isotopically labelled water allowed distinguishing between the species originating in the gas phase and those formed in the liquid. The plasma equipment was contained inside a Faraday cage to eliminate possible influence of any external field. The setup is versatile and can aid in further understanding the cold plasma-liquid interactions chemistry.

An experimental setup was created for the helium-operated kHz frequency plasma jet. The setup includes a cage for the plasma power supply and jet and an in-house built reactor to monitor plasma-induced reactive species without the interference of the ambient atmosphere.

大气压等离子体设置调查活性物种形成

Non-thermal atmospheric pressure (&#39;cold&#39;) plasmas have received increased attention in recent years due to their significant biomedical potential. ...

Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with one twist grain boundary. This apparatus utilizes high uniaxial pressure and a pulsed direct current for rapid consolidation of material. Diffusion bonding of strontium titanate bicrystals without fracture, in a spark plasma sintering apparatus, is possible at high pressures due to the unusual temperature dependent plasticity behavior of strontium titanate. We demonstrate a method for the successful formation of bicrystals at accelerated time scales and lower temperatures in a spark plasma sintering apparatus compared to bicrystals formed by conventional diffusion bonding parameters. Bond quality was verified by scanning electron microscopy. A clean and atomically abrupt interface containing no secondary phases was observed using transmission electron microscopy techniques. Local changes in bonding across the boundary was characterized by simultaneous scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy.

A viable technique for the formation of strontium titanate bicrystals at high pressure and fast heating rate via the spark plasma sintering apparatus is developed.

放电等离子烧结设备中使用的钛酸锶双晶体的形成

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with ...