Meaney K D, Jeet J, Carrera J, Mariscal E, Schlossberg D, Moore A, Eckart M, Milnes J, Hink P, Hillyard P, Holdener D, Herrmann H, Geppert-Kleinrath H, Kim Y
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Rev Sci Instrum. 2024 Dec 1;95(12). doi: 10.1063/5.0213471.
When an inertial confinement fusion implosion is compressed, it maintains thermonuclear density and temperatures for a very short time scale, about 100 ps. The Gamma Reaction History diagnostic measures the time evolution of the fusion burn, but its temporal resolution is limited by the use of a photomultiplier tube (PMT) to amplify the photon signal. Multichannel plate-based PMTs have a fast (∼120 ps) full-width at half-max impulse response function (IRF), but the time scale is similar to the incoming physics signal. An analysis routine is used to remove the effect of the PMT IRF and infer the incident fusion burnwidth. With the National Ignition Facility achieving ignition and creating much brighter signals, the PMTs are run at gains three orders of magnitude lower than nominal operation. Calibration at these settings shows the PMT IRFs get ∼15% wider. Taking the gain-dependent IRF can affect the inferred nuclear burnwidths by up to ∼15%.
当惯性约束聚变内爆被压缩时，它会在非常短的时间尺度（约100皮秒）内维持热核密度和温度。伽马反应历史诊断技术测量聚变燃烧的时间演化，但其时间分辨率受限于使用光电倍增管（PMT）来放大光子信号。基于多通道板的光电倍增管具有快速（约120皮秒）的半高全宽脉冲响应函数（IRF），但该时间尺度与入射的物理信号相似。一种分析程序被用于消除光电倍增管脉冲响应函数的影响，并推断入射聚变燃烧宽度。随着国家点火设施实现点火并产生亮得多的信号，光电倍增管的增益运行在比标称运行低三个数量级的水平。在这些设置下的校准表明，光电倍增管的脉冲响应函数变宽约15%。考虑增益相关的脉冲响应函数可能会使推断的核燃烧宽度变化高达约15%。
