Publications

Chavez, Marcus A.; Covert, Timothy T.

Abstract not provided.

Chavez, Marcus A.; Willis, Michael D.; Chavez, Marcus A.; Willis, Michael D.; Covert, Timothy T.

Abstract not provided.

Covert, Timothy T.; Willis, Michael D.; Radtke, Gregg A.

The Light Initiated High Explosive (LIHE) facility performs high rigor, high consequence impulse testing for the nuclear weapons (NW) community. To support the facility mission, LIHE's extensive data acquisition system (DAS) is comprised of several discrete components as well as a fully integrated system. Due to the high consequence and high rigor of the testing performed at LIHE, a measurement assurance plan (MAP) was developed in collaboration with NW system customers to meet their data quality needs and to provide assurance of the robustness of the LIHE DAS. While individual components of the DAS have been calibrated by the SNL Primary Standards Laboratory (PSL), the integrated nature of this complex system requires verification of the complete system, from end-to-end. This measurement assurance plan (MAP) report documents the results of verification and validation procedures used to ensure that the data quality meets customer requirements.

Covert, Timothy T.

The Light Initiated High Explosive facility utilized a spray deposited coating of silver acetylide - silver nitrate explosive to impart a mechanical shock into targets of interest. A diagnostic was required to measure the explosive deposition in - situ. An X - ray fluorescence spectrometer was deployed at the facility. A measurement methodology was developed to measure the explosive quantity with sufficient accuracy. Through the use of a tin reference material under the silver based explosive, a field calibration relationship has been developed with a standard deviation of 3.2 % . The effect of the inserted tin material into the experiment configuration has been explored.

Chavez, Marcus A.; Willis, Michael D.; Covert, Timothy T.

Abstract not provided.

Chavez, Marcus A.; Willis, Michael D.; Covert, Timothy T.

The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.

Chavez, Marcus A.; Covert, Timothy T.

Abstract not provided.

Covert, Timothy T.; Chavez, Marcus A.

Abstract not provided.

Covert, Timothy T.

The Light Initiated High Explosive (LIHE) Facility uses a robotic arm to spray explosive material onto test items for impulse tests. In 2007, the decision was made to replace the existing PUMA 760 robot with the Staubli TX-90XL. A qualification plan was developed and implemented to verify the safe operating conditions and failure modes of the new system. The robot satisfied the safety requirements established in the qualification plan. A performance issue described in this report remains unresolved at the time of this publication. The final readiness review concluded the qualification of this robot at the LIHE facility.

Covert, Timothy T.; Rivera, Wayne G.

Abstract not provided.

Covert, Timothy T.

A velocity interferometer system for any reflector (VISAR) was recently deployed at the light initiated high explosive facility (LIHE) to measure the velocity of an explosively accelerated flyer plate. The velocity data from the flyer plate experiments, using the vendor's fringe constant of 100m/s/fringe, were consistently lower than model predictions. The goal of the VISAR validation test series was to confirm the VISAR system fringe constant. A low velocity gas gun was utilized to impact and accelerate a target at the LIHE facility. VISAR velocity data from the accelerated target was compared against an independent velocity measurement. The data from this test series did in fact reveal the fringe constant was significantly higher than the vendor's specification. The correct fringe constant for the LIHE VISAR system has been determined to be 123 m/s/fringe. The Light Initiated High Explosive (LIHE) facility recently completed a Phase I test series to develop an explosively accelerated flyer plate (X-Flyer). The X-Flyer impulse technique consists of first spraying a thin layer of silver acetylide silver nitrate explosive onto a thin flyer plate. The explosive is then initiated using an intense flash of light. The explosive detonation accelerates the flyer across a small air gap towards the test item. The impact of the flyer with the test item creates a shock pulse and an impulsive load in the test unit. The goal of Phase I of the X-Flyer development series was to validate the technique theory and design process. One of the key parameters that control the shock pulse and impulsive load is the velocity of the flyer at impact. To measure this key parameter, a velocity interferometer system for any reflector (VISAR) was deployed at the LIHE facility. The VISAR system was assembled by Sandia personnel from the Explosive Projects and Diagnostics department. The VISAR was a three leg, push-pull system using a fixed delay cavity. The primary optical components consisted of a delay bar and stand off that holds the air-reference mirror. When this component was ordered 2 years ago, a fringe constant of 100 m/s/fringe for a 532nm laser was specified. The fabrication/assembly vendor went out of business shortly after delivering the component and did not deliver the certification papers with the component. The vendor documentation to verify the fringe constant was not made available to Sandia. VISAR systems were generally not calibrated because the fringe constant could be determined from a known glass index of refraction and length. The VISAR system was deployed at the LIHE facility using the specified 100m/s/fringe. The Phase I X-Flyer development series was completed successfully measuring flyer velocities using the VISAR system. However flyer velocity measurements were on average 18% lower than analytical model predictions. In an effort to resolve the consistently slow velocity data, the VISAR data was under scrutiny. The purpose of the LIHE VISAR validation test series is to verify the velocity data taken with the VISAR system.

Bender, Susan F.; Anderson, Heidi A.; Bender, Susan F.; Steyskal, Michele S.; Ingram, Brian I.; Melof, Brian M.; Fleming, Kevin J.; Broyles, Theresa A.; Mulligan, Edward J.; Covert, Timothy T.

Diversionary devices such as flashbang grenades are used in a wide variety of military and law-enforcement operations. They function to distract and/or incapacitate adversaries in scenarios ranging from hostage rescue to covert strategic paralysis operations. There are a number of disadvantages associated with currently available diversionary devices. Serious injuries and fatalities have resulted from their use both operationally and in training. Because safety is of paramount importance, desired improvements to these devices include protection against inadvertent initiation, the elimination of the production of high-velocity fragments, less damaging decibel output and increased light output. Sandia National Laboratories has developed a next-generation diversionary flash-bang device that will provide the end user with these enhanced safety features.