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Hardened, Optically-Based Temperature Characterization of Detonation Environments

Description:

TECHNOLOGY AREA(S): Sensors, Weapons 

OBJECTIVE: The objectives of this effort are to: 1) Develop an optically based temperature diagnostic (for characterizing temperature fields ranging 300-3000 K) to interrogate detonation environments and 2) provide a hardened/scalable capability for interrogating a detonation environment. 

DESCRIPTION: Weapon-target interaction during a counter-WMD operation and ensuing neutralization within the target environment need to be characterized and understood to evaluate the full effect of counter-WMD operations on targets. Characterization capabilities are needed to assess the confidence in immediate lethality of a weapon formulation against an agent and potential longer term viability of the threat. The immediate payoff of these research efforts is expected to be the development of a diagnostic to quantify localized temporal evolution of temperature, inside a blast/fireball, which in turn will vastly improve blast and weapon modeling. This diagnostic development is critical for predicting weapon effectiveness against WMD targets. Therefore, the work from this topic will help generate statistically richer data sets for future decision making in support of defense applications. Over the last decade or more, the combustion community has made significant advances in laser based diagnostic capabilities [1-4]. A number of techniques have demonstrated great promise in this field (e.g. Coherent Anti-Stokes Raman Spectroscopy (CARS), Planar Laser Induced Fluorescence (PLIF), absorption spectroscopy (single mode and supercontinuum), etc.). The detonation science community has been slow to adopt some of these innovative capabilities either due to cost, personnel expertise, or technological/logistical risk. Some of these reasons may no longer be sufficient nor applicable; however, some challenges still remain. Some universities and other government laboratories have made progress in terms of characterizing temperature and other metrics of interest [5]. The topic here is focused solely on temperature characterization in a post-detonation field that includes CHNO and metallized charges. If pulsed laser capabilities are chosen in response to this topic, then high repetition rate lasers (>1 kHz) are desired. Capabilities that lend well to characterizing a temperature field (e.g. 2D field or 3D volume) are also of interest. Point/line integrated capabilities (excluding H2O absorption) that may complement existing non-optical capabilities to enhance statistical collection would also be relevant. Some challenges in characterizing detonation environments persist. For consideration within this topic, offerors need to consider the high optical thickness of the associated fireball (approaching 5-6 logs in some regimes). Other environmental challenges include being in particle laden flows and the harsh blast pressure and temperature environments that may damage equipment in or near the fireball. Consider that other enabling technologies (e.g fiber lasers, QCLs, LWIR fiber) may make a concept transitionable from a university lab environment to a fieldable capability. The scalability (e.g costs, number of sensors, etc.) of a given concept along with generating sufficient statistics (e.g. time domain, spatial domain, etc.) for detonation environments will be important considerations. 

PHASE I: ) Develop an optically based and cost-scalable sensing capability for characterizing a large range of temperatures 500K-3000K for small scale detonation (or simulated detonation). 2) Demonstrate concept in a (simulated) blast environment. 

PHASE II: 1) Produce a breadboard capability that is hardenable/scalable for field testing. 2) Ship for preliminary performance evaluation to a Navy lab and/or other test facility. 3) Demonstrate performance over temperature range in a mid-scale detonation test. Stand-alone capabilities or those that are orthogonal to exisiting (non-optical) capabilities which might enhance statistical collection are of interest. Hardening measures and/or beam transport will need to be considered. 

PHASE III: Team up with a DoD Laboratory or commercial partner to develop a commercial instrument for military applications of interest to DTRA and the DoD, or for applications of interest to the petroleum and chemical industries. 

REFERENCES: 

1: Chloe E. Dedic, Terrence R. Meyer, and James B. Michael, "Single-shot ultrafast coherent anti-Stokes Raman scattering of vibrational/rotational nonequilibrium," Optica 4, 563-570 (2017).​​

2:  T. Werblinski, S.R. Engel, R. Engelbrecht, L. Zigan, S. Will, "Temperature and mult-species measurements by supercontinuum absorption spectroscopy for IC engine applications," Optics Express 21, (2013). ​​

3:  S. P. Kearney and D. R. Guildenbecher, "Temperature and oxygen measurements in a metallized propellant flame by hybrid fs/ps rotational coherent anti-Stokes Raman scattering," in Imaging and Applied Optics 2016, OSA technical Digest (online) (Optical Society of America, 2016), paper LW5G.3.​​

4:  Anna-Lena Sahlberg, Dina Hot, Johannes Kiefer, Marcus Aldén, Li Zhongshan, "Mid-infrared laser-induced thermal grating spectroscopy in flames", Proceedings of the Combustion Institute, 36, 4515-4523 (2017).​​

5:  DTRA Basic Research Broad Agency Announcement HDTRA1-11-21-BRCWMD-BAA, Period F-Topic 7: Dynamic Characterization of Post-Detonation Fireballs Involving Agent Defeat Additives and Agent Simulants​​

KEYWORDS: Temperature, Lasers, Spectroscopy, Weapons 

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