Nagel S R, Hilsabeck T J, Bell P M, Bradley D K, Ayers M J, Piston K, Felker B, Kilkenny J D, Chung T, Sammuli B, Hares J D, Dymoke-Bradshaw A K L
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA.
General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
Rev Sci Instrum. 2014 Nov;85(11):11E504. doi: 10.1063/1.4890396.
The DIlation X-ray Imager (DIXI) is a new, high-speed x-ray framing camera at the National Ignition Facility (NIF) sensitive to x-rays in the range of ≈2-17 keV. DIXI uses the pulse-dilation technique to achieve a temporal resolution of less than 10 ps, a ≈10× improvement over conventional framing cameras currently employed on the NIF (≈100 ps resolution), and otherwise only attainable with 1D streaked imaging. The pulse-dilation technique utilizes a voltage ramp to impart a velocity gradient on the signal-bearing electrons. The temporal response, spatial resolution, and x-ray sensitivity of DIXI are characterized with a short x-ray impulse generated using the COMET laser facility at Lawrence Livermore National Laboratory. At the NIF a pinhole array at 10 cm from target chamber center (tcc) projects images onto the photocathode situated outside the NIF chamber wall with a magnification of ≈64×. DIXI will provide important capabilities for warm-dense-matter physics, high-energy-density science, and inertial confinement fusion, adding important capabilities to temporally resolve hot-spot formation, x-ray emission, fuel motion, and mix levels in the hot-spot at neutron yields of up to 10(17). We present characterization data as well as first results on electron-transport phenomena in buried-layer foil experiments.
膨胀X射线成像仪(DIXI)是国家点火装置(NIF)上一台新型的高速X射线分幅相机,对能量范围约为2 - 17 keV的X射线敏感。DIXI采用脉冲膨胀技术实现了小于10皮秒的时间分辨率,相比目前NIF上使用的传统分幅相机(分辨率约为100皮秒)有大约10倍的提升,而这种分辨率在其他情况下只有通过一维条纹成像才能实现。脉冲膨胀技术利用电压斜坡在承载信号的电子上施加速度梯度。DIXI的时间响应、空间分辨率和X射线灵敏度通过劳伦斯利弗莫尔国家实验室的COMET激光装置产生的短X射线脉冲来表征。在NIF,距靶室中心(tcc)10厘米处的针孔阵列将图像投射到位于NIF腔壁外的光电阴极上,放大倍数约为64倍。DIXI将为温稠密物质物理、高能量密度科学和惯性约束聚变提供重要能力,在中子产额高达10(17)时,为在时间上分辨热点形成、X射线发射、燃料运动以及热点中的混合水平增加重要能力。我们展示了表征数据以及埋层箔实验中电子输运现象的初步结果。