Ultrafast Velocity Measurement of Shock Wave using Microwave Photonic Velocimetry

该奖项支持一种新的传感模式，即微波光子测速（MPV）的基础研究。在冲击波实验中，测速是测量冲击波在发展、传播和衰减时的速度。这提供了关于冲击波行为的关键信息。该项目的目标是支持现场和实时测量超快冲击波的速度，其速度约为几十公里/秒。这将使高能材料的研究成为可能，并最终导致更安全的工业工作场所，爆炸可能会造成危险。能够测量超快冲击波的鲁棒且精确的速度测量是一项突出的技术挑战，限制了我们对冲击波物理和化学的理解。如果成功，MPV技术将填补这一空白，大大扩展我们对材料在各种物理条件（温度、压力、浓度等）下爆炸能力的了解。因此，该项目所追求的MPV突破将在预防灾害和提高危险环境中的安全性方面产生重大的社会效益。特别是，MPV预计将成为安全处理和储存非理想（临界）爆炸物的有利工具。这些材料通常被认为是安全的，但在某些条件下可能成为工作场所的致命威胁。具体的研究目标包括理解和表征MPV概念，研究新的信号处理方法，并使用大规模的户外爆炸测试来验证这种新的传感方式。直接的结果是MPV概念的基本知识，实施和演示。主要创新包括：1）微波和光波之间的相互作用的创新使用，使得能够创建精确、鲁棒和低成本的速度计，2）在MPV系统中创新地集成光学频率梳技术，以精确地分离在频域中测量的元件，3）具有集成渐变折射率光纤（GIF）准直器的新型MPV探头，其显著增强MPV的性能，4）一种新颖的信号处理算法，其智能地重建爆炸事件的速度历史轮廓，以及5）增强的多路复用能力，允许同时进行多探头冲击波速度测量。

This award supports fundamental research on a novel sensing modality, namely, microwave photonic velocimetry (MPV). In shock wave experimentation, velocimetry is the measurement of the speed of a shock wave as it develops, propagates, and fades. This provides critical information on shock wave behavior. The goal of this project is to support the measurement of the velocity of ultrafast shock waves, traveling at speeds in the order of several tens of km/s, in-situ and in real-time. This will enable the study of energetic materials, and eventually lead to much safer industrial workplaces where explosions may pose a hazard. Robust and accurate velocimetry that can measure ultrafast shock waves is an outstanding technical challenge that limits our understanding of shock wave physics and chemistry. If successful, the MPV technology will fill this void by substantially expanding our knowledge of materials' ability to detonate under a wide variety of physical conditions (temperature, pressure, concentration, etc.). Thus, breakthroughs in MPV as pursued in this project, will have significant societal benefits in preventing disasters and improving safety in hazardous environments. In particular, MPV is anticipated to be an enabling tool in the safe handling and storage of non-ideal (borderline) explosives. These are materials that are conventionally rated as safe, but may become a deadly threat in workplaces under certain conditions. Specific research objectives include understanding and characterizing the MPV concept, investigating novel signal processing methodologies, and validating this novel sensing modality using large-scale, outdoor detonation tests. The direct outcome is the fundamental knowledge, implementation, and demonstration of the MPV concept. Key innovations include: 1) the innovative use of interactions between microwave and optical waves, enabling the creation of a precise, robust, and low-cost velocimetery, 2) the innovative integration of optical frequency comb technologies in the MPV system to precisely separate elements measured in the frequency-domain, 3) the novel MPV probe with integrated graded index fiber (GIF) collimator, which significantly enhances MPV's performance, 4) a novel signal processing algorithm that intelligently reconstructs the velocity history profiles of explosion events, and 5) enhanced multiplexing capability allowing for simultaneous, multi-probe shock wave velocity measurement.