Geppert-Kleinrath H, Herrmann H W, Kim Y H, Zylstra A B, Meaney K, Lopez F E, Pederson B J, Carrera J, Khater H, Horsfield C J, Rubery M S, Gales S, Leatherland A, Meadowcroft A, Hilsabeck T, Kilkenny J D, Malone R M, Hares J D, Dymoke-Bradshaw A K L, Milnes J, McFee C
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Rev Sci Instrum. 2018 Oct;89(10):10I146. doi: 10.1063/1.5039377.
The Cherenkov mechanism used in Gas Cherenkov Detectors (GCDs) is exceptionally fast. However, the temporal resolution of GCDs, such as the Gamma Reaction History diagnostic at the National Ignition Facility (NIF), has been limited by the current state-of-the-art photomultiplier tube technology to ∼100 ps. The soon-to-be deployed Pulse Dilation Photomultiplier Tube (PD-PMT) at NIF will allow for temporal resolution comparable to that of the gas cell or ∼10 ps. Enhanced resolution will contribute to the quest for ignition in a crucial way through precision measurements of reaction history and ablator areal density (ρR) history, leading to better constrained models. Features such as onset of alpha heating, shock reverberations, and burn truncation due to dynamically evolving failure modes may become visible for the first time. Test measurements of the PD-PMT at Atomic Weapons Establishment confirmed that design goals have been met. The PD-PMT provides dilation factors of 2 to 40× in 6 increments. The GCD-3 recently deployed at the NIF has been modified for coupling to a PD-PMT and will soon be making ultrafast measurements.
气体切伦科夫探测器（GCD）中使用的切伦科夫机制速度极快。然而，GCD的时间分辨率，比如国家点火装置（NIF）的伽马反应历史诊断，目前受限于最先进的光电倍增管技术，约为100皮秒。即将在NIF部署的脉冲扩展光电倍增管（PD-PMT）将实现与气室相当的时间分辨率，即约10皮秒。更高的分辨率将通过对反应历史和烧蚀面密度（ρR）历史的精确测量，对实现点火研究起到关键作用，从而得出约束性更强的模型。诸如α加热开始、激波反射以及因动态演化的失效模式导致的燃烧截断等特征可能首次变得可见。在原子武器机构对PD-PMT进行的测试测量证实已达到设计目标。PD-PMT以6种增量提供2至40倍的扩展因子。最近在NIF部署的GCD-3已进行改装，以便与PD-PMT耦合，并且很快将进行超快测量。
