Isaac R. Shokair

Performance of an induction coil launcher

Performance of an electromagnetic induction launcher is considered for three types of armatures. These are: solid; 1-element wound; and 16-element wound aluminum armatures. The one element wound armature has uniform current density throughout and thus can withstand field reversal (working against embedded armature flux) and still maintain low temperature. Slingshot simulations were performed for several configurations. Best performance was obtained for a single element wound armature with two field reversals. For a 60 kg projectile, 10.5 cm coil inner radius and 5.5 cm coil build, the velocity after 50 meters of launcher length (670 stages) exceeded 3.5 km/sec with an overall efficiency of about 45%. For the same parameters the solid and 16-element wound armatures reach a velocity of about 3.3 km/sec after 800 stages (60 meters of launcher length) but without field reversal. A velocity of 3.5 km/sec is possible after 60 meters of launcher length with the 16-element wound armature with one field reversal, but the temperature is close to the melting temperature of aluminum. >

Design and evaluation of coils for a 50 mm diameter induction coilgun launcher

Coilguns have the ability to provide magnetic pressure to projectiles which results in near constant acceleration. The authors have developed coils to produce an effective projectile base pressure of 100 MPa (1 kbar) as a step toward reaching base pressures of 200 MPa. The design uses a scalable technology applicable to the entire range of breech to muzzle coils of a multi-stage launcher. This paper presents the design of capacitor-driven coils for launching nominal 50 mm, 350 g projectiles. Design criteria, constraints, mechanical stress analysis, launcher performance, and test results are discussed. >

Development of an unattended ground sensor for ultraviolet laser-induced fluorescence detection of biological agent aerosols

A prototype of an unattended ground sensor has been developed for detection of biological agent aerosols. This point sensor uses ultraviolet laser induced fluorescence (UV LIF) to detect aerosol biological microorganisms collected on filter media. The concept can be designed to be compact, low power, and hardened to survive harsh delivery environments such as airdrop. The prototype consists of an air sampling system, a filter exchange mechanism, an Nd:YAG microlaser that is frequency tripled and quadrupled to generate 355-nm and 266-nm excitation wavelengths, a spectrometer, an intensified CCD detector, and a data acquisition and control system. The analysis utilizes a spectral database of fluorescence signatures of biological organisms and common interferents measured by Sandia for the Armys Edgewood Research and Development Engineering Center (ERDEC) and the Department of Energys Chemical and Biological Non-proliferation (DOE CBNP) program. The analysis algorithms are based on algorithms developed by Sandia for an airborne UV LIF lidar system.

Projectile transverse motion and stability in electromagnetic induction launchers

The transverse motion of a projectile in an electromagnetic induction launcher is considered. The equations of motion for translation and rotation are derived assuming a rigid projectile and a flyway restoring force per unit length that is proportional to the local displacement. Linearized transverse forces and torques due to energized coils are derived for displaced or tilted armature elements based on a first order perturbation method. The resulting equations of motion for a rigid projectile composed of multiple elements in a multi-coil launcher are analyzed as a coupled oscillator system of equations and a simple linear stability condition is derived. The equations of motion are incorporated into the 2-D Slingshot circuit code and numerical solutions for the transverse motion are obtained. >

Development of an integrated microfluidic instrument for unattended water-monitoring applications.

Field‐deployable detection technologies in the nations water supplies have become a high priority in recent years. The unattended water sensor is presented which employs microfluidic chip‐based gel electrophoresis for monitoring proteinaceous analytes in a small integrated sensor platform. The instrument collects samples directly from a domestic water flow. The sample is then processed in an automated microfluidic module using in‐house designed fittings, microfluidic pumps and valves prior to analysis via Sandias μChemLab™ module, which couples chip‐based electrophoresis separations with sensitive LIF detection. The system is controlled using LabVIEW software to analyze water samples about every 12 min. The sample preparation, detection and data analysis has all been fully automated. Pressure transducers and a positive control verify correct operation of the system, remotely. A two‐color LIF detector with internal standards allows corrections to migration time to account for ambient temperature changes. The initial unattended water sensor prototype is configured to detect protein biotoxins such as ricin as a first step toward a total bioanalysis capability based on protein profiling. The system has undergone significant testing at two water utilities. The design and optimization of the sample preparation train is presented with results from both laboratory and field testing.

Measuring axially varying beam position using B -dot monitors

For charged‐particle beam experiments, it is often necessary to measure the transverse position of a beam that is undergoing oscillations as it propagates axially in a conducting tube. This is usually done using small wire loops called B‐dot monitors which measure the change of magnetic flux. If the monitors are located at a radius R, which is of the same order as the wavelength of the beam oscillations, the B‐dot signal and the beam transverse position are related in a nonlocal manner. We consider this situation here and derive an integral equation relating the beam position to the B‐dot signals, for arbitrary displacement profiles, in the limit of small beam displacements. Solutions of this equation are obtained for special cases along with a numerical method for solving the general problem.

Application of Microseparation Arrays to the Detection of Biotoxins in Aerosol Backgrounds

We are investigating the use of parallel separation channels that utilize orthogonal separation techniques as a platform for a biosensor to accurately identify protein biotoxins. Two separation techniques were initially chosen for proof of concept demonstration—capillary zone electrophoresis (CZE) and capillary gel electrophoresis (CGE)—and have been implemented in our compact “µChemLab™” device. This device integrates automated high-voltage control of microchip-based separations with laser-induced fluorescence (LIF) detection and on-board data analysis. The effectiveness of this two-channel approach was evaluated using biotoxin-spiked aerosol samples.

Concept for maritime near-surface surveillance using water Raman scattering

We discuss a maritime surveillance and detection concept based on Raman scattering of water molecules. Using a range-gated scanning lidar that detects Raman scattered photons from water, the absence or change of signal indicates the presence of a non-water object. With sufficient spatial resolution, a two-dimensional outline of the object can be generated by the scanning lidar. Because Raman scattering is an inelastic process with a relatively large wavelength shift for water, this concept avoids the often problematic elastic scattering for objects at or very close to the water surface or from the bottom surface for shallow waters. The maximum detection depth for this concept is limited by the attenuation of the excitation and return Raman light in water. If excitation in the UV is used, fluorescence can be used for discrimination between organic and non-organic objects. In this paper, we present a lidar model for this concept and discuss results of proof-of-concept measurements. Using published cross section values, the model and measurements are in reasonable agreement and show that a sufficient number of Raman photons can be generated for modest lidar parameters to make this concept useful for near-surface detection.

Preliminary performance assessment of biotoxin detection for UWS applications using a MicroChemLab device.

In a multiyear research agreement with Tenix Investments Pty. Ltd., Sandia has been developing field deployable technologies for detection of biotoxins in water supply systems. The unattended water sensor or UWS employs microfluidic chip based gel electrophoresis for monitoring biological analytes in a small integrated sensor platform. This instrument collects, prepares, and analyzes water samples in an automated manner. Sample analysis is done using the {mu}ChemLab{trademark} analysis module. This report uses analysis results of two datasets collected using the UWS to estimate performance of the device. The first dataset is made up of samples containing ricin at varying concentrations and is used for assessing instrument response and detection probability. The second dataset is comprised of analyses of water samples collected at a water utility which are used to assess the false positive probability. The analyses of the two sets are used to estimate the Receiver Operating Characteristic or ROC curves for the device at one set of operational and detection algorithm parameters. For these parameters and based on a statistical estimate, the ricin probability of detection is about 0.9 at a concentration of 5 nM for a false positive probability of 1 x 10{sup -6}.