The Department of Defense, through the Defense Threat Reduction Agency (DTRA), is seeking innovative solutions under the Small Business Innovation Research (SBIR) program for the development of a predictive methodology aimed at optimizing tamped direct laser impulse parameters. The objective is to create a fast-running tool or methodology that can accurately determine the necessary laser and tamper parameters to achieve a specified impulse on various materials or 3D structures, addressing the complexities of modeling uncertainties and experimental variabilities. This initiative is crucial for advancing the capabilities of impulse delivery systems in defense applications, particularly in the context of materials testing since the cessation of underground nuclear testing. Interested parties should note that the solicitation is currently closed, with the application due date having been set for October 23, 2024, and further details can be accessed through the DOD SBIR website.

## Description

Since the cessation of underground nuclear testing, the Department of Defense has utilized multiple types of simulators to impart relevant impulses to materials, structures, and systems. Recently, it has become possible to utilize lasers to impart relevant impulses directly on material coupon samples and 3D structures on the 1-1000 cm2 scale, with or without the use of transparent tampers. It is known that the resultant impulse imparted into a material, structure, or system will depend on the laser parameters (energy, pulse shape, wavelength), tamper parameters (material, thickness, adhesion layer), and substrate material thickness and geometry. While it is possible to model with varying degrees of uncertainty the relevant physics and materials interaction to predict the resulting impulse for a given set of parameters, there doesn&rsquo;t currently exist a predictive tool for experimental design that can work backwards from a desired impulse strength and profile to calculate the appropriate laser and tamper parameters. Multiple modeling uncertainties and experimental variabilities complicate predictive modeling of the resultant impulse. It is desired that any technical approach, method, or tool for predicting direct laser impulse be able to determine and propagate these uncertainties to inform and bound experimental design. Experimental variabilities include, but are not limited to, laser power, laser timing and pulse shape, laser spatial uniformity, tamper uniformity, tamper adhesion, substrate surface preparation, and diagnostic response.Of particular interest are laser parameters between 6J/cm2 and 30J/cm2 with square laser pulses between 5-20ns at 2&omega; (0.53 &micro;m). Substrate materials of interest include, but are not limited to, aluminum, titanium, stainless steel, and tape wound carbon phenolics. Tamper materials of interest include, but are not limited to, PTFE tape, fused silica, sapphire, and LiF. 

## Objective

Develop and demonstrate a fast-running approach, tool, or methodology for determining the necessary laser and tamper parameters to achieve a desired impulse on a material or 3D structure of interest.

## Phase I

The primary deliverable of Phase 1 is a technical approach, conceptual method, or tool concept for backward calculating laser and tamper parameters to deliver a specified impulse and predict diagnostic signals, such as PDI. A proof of concept with 1D code, flat samples, and limited materials is acceptable for Phase 1. 

## Phase II

Phase 2 should focus on the development and refinement of the technical approach, method, or tool from Phase 1, including the addition of multiple substrate and tamper materials. Phase II should include an approach to 3D structures and graded tampers as well as propagation of uncertainties. It is suggested that Phase 2 include verification and validation through a comparison to existing experimental data. 

## Phase III: Dual Use Applications

Phase 3 may involve additional refinement of the technical approach, method, or tool developed in prior phases as well as integration of prior test data and diagnostic outputs. Further, Phase 3 may include automation, development of user interfaces, and additional substrates and tamper materials. Verification and validation with multiple experimental results would also be expected in Phase 3.

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