Proprietary Instrumentation
and Data Acquisition Systems
Impulse Gauges in Saturn |
Raytheon Ktech’s Applied Physics and Testing staff has over 30 years experience evaluating the dynamic response of materials and structures exposed to blasts, explosions, fire, and other energetic stimuli. Our experience in the design, implementation, and analysis of military weapon effects testing has enabled us to develop innovative sensors, measurement techniques, and simulations for a variety of applications. Our custom specialty instrumentation includes piezoelectric stress gauges, interferometry, pulsed radiation source diagnostics, and fire diagnostics
Piezoelectric shock sensors and gauges
Raytheon Ktech Corporation supplies piezoelectric shock sensors and a number of piezoelectric gauge assemblies. Customers can build the sensors into their own test assemblies or buy a complete gauge assembly that can be customized is required. Both crystal and thin film polymer piezoelectric materials are available.
Crystal Transducers
Quartz shock gauges
X-cut quartz is one of the most accurate and reproducible materials for measuring short-duration, one-dimensional stress pulses. Raytheon Ktech’s gauges operate in the current mode and are configured with an internal shunted center electrode and guard ring.
The electrical output is well characterized up to a maximum stress of 2.5GPa (25kbar). The response time of the gauges is less than 1 nanosecond and the useful "read-time" of the gauge is limited to one transit time through the thickness of the crystal which is typically 0.2-1.0 microseconds. Signal conditioning is not required, but high bandwidth cable and data acquisition systems are required for measuring full performance
All standard quartz gauges have internal 50-Ohm current viewing resistors (CVRs) and internally shunted guard rings. Guard ring widths are 1.5 times the crystal thickness. Standard output connectors are SMA-type. Gauge housing is 6061-T6 Aluminum.
Lithium Niobate Gauges
Lithium niobate piezoelectric sensors are used in a manner similar to x-cut quartz for the measurement of short duration stress waves. Lithium niobate has a higher shock impedance than x-cut quartz and a higher sensitivity. Therefore, it provides some flexibility to the experiment designer when dealing with higher impedance materials and/or low amplitude limits are lower than than x-cut quartz.
Hopkinson Bars
Split Hopkinson bars with lithium niobate sensors have been used to measure relatively long duration (6 t o 10 µs) air blasts. Raytheon Ktech can customize Hopkinson bar gauge assemblies.
Shear Mode Resonators
Raytheon Ktech's engineers and technicians have developed special expertise in the research, development, and design of sensors and sensors systems. Recently, Raytheon Ktech personnel assisted Sandia National Laboratories and a multinational commercial company develop sensor systems using thickness shear mode (TSM) acoustic sensor technology.
SM sensor technology allows fluid properties such as density, viscosity, and liquid-to-solid phase changes to be measured with greater accuracy and efficiency. Very subtle changes in mass deposition and viscoelastic character of deposited mass can also be determined. The TSM resonator is high sensitivity device, with a sensitivity greater than 5ng/cm2. The sensor is small and allows in-situ, real-time measurements. Sample sizes can be less than 1 cc.
Services:
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Sensor system mechanical design
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Sensor system electrical design
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Fabrication of sensor systems
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Characterization of sensor response
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Application of sensor systems to measurement problems in extreme environments
Specific Applications for TSM technology include:
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Fuel oxidation measurement
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Aircraft wing ice detection
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Cleaning bath effectiveness
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Fluid viscosity/density monitoring
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Mass deposition
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Cloud point determination
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Electro deposition monitoring
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Biological sensors
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Dew point measurements
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Fluid pH measurement
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Film property measurement
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Detection of volatile organic compounds in water
Thin Film Transducers
Raytheon Ktech’s thin film transducers use the piezoelectric polymer polyvinylidine fluoride (PVDF). We are the North American agent for and part owner of Piezotech SA, the only company licensed to manufacture PVDF sensors using the Bauer hysteretic poling method.
Polyvinylidine fluoride (PVDF) gauges can measure transient pressures from 1 KPa to 40GPa. They are uniquely suited for the measurement of propagating stress waves. They are thin (less than 25 µm), self powered, high-output gauges that are adaptable to complex contours. PVDF sensors are available in a variety of configurations.
Sensor Configurations
The Piezotech PVDF shock sensors are manufactured from 26-µm thick biaxially-stretched film and poled using the Bauer method. The orientation of the square, poled, sensor area relative to the PVDF stretching axes (1 and 2) is indicated. The PVDF film is electroded by sputtering 0.25 µm gold over 0.05 µm platinum on the surfaces of the film.
Piezotech SA also produces a time-of-arrival (TOA) shock sensor that is not as accurately noted but is more than adequate to generate a well-defined signal upon shock arrival. TOA sensors can be purchased with or without R6-174 cables and connectors.
Optical Impulse Gauges
Raytheon Ktech has developed the Optical Impulse Gauge (OIG) for the measurement of blowoff impulse in radiation simulators.
The OIG is mounted in a secondary enclosure using a rubber shock isolation system to to isolate the system from radiation simulator machine shock. This secondary enclosure is placed behind a debris shield that shields the enclosure from radiation and retards the expansion of source and filter debris. Without the debris shield, early radiation/debris induced motions of the secondary enclosure severely limit the useful data obtained from the OIG.
Optical Impulse Gauge Technical Description
The OIG measures impulse by monitoring the equilibrium velocity of a known mass that is free to move along on axis. The sample holder/carriage is 31-mm long and weighs approximately 25 grams. The carriage slides on a miniature ball slide. The short axial length of the carriage allows it to equilibriate within 50µs of the stimulus. The impulse gauge employs a simple, but high resolution optical position encoder. Each OIG produces two outputs that are out of phase (quadrature) so that carriage reversal can be detected. The OIG requires a signal conditioning unit and power supply that are located outside the simulator test chamber. A shielded seven conductor cable is used to communicate between the signal conditioner and the OIG.
The OIG has an impulse resolution of 100 tap and a 50-µs time resolution. High impulses can be measured by selecting an appropriate carriage mass. The carriage is designed to accept supplementary weights. Typical recording times range from 500 to 1000 µs.
Specifications
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Measures blowoff impulse in radiation simulators
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Impulse resolution of 100 tap
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50 µs time resolution
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Typical recording timers range form 500 to 1000 µs
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Primary and secondary housing shield gauge from radiation, isolates system from simulator machine shock and retards the expansion of source and filter debris
Calorimetry
Applied Physics and Testing has the specialized expertise to provide accurate diagnostics for pulsed radiation sources. We have developed wide x-ray calorimeters to diagnose soft x-ray, Bremsstrahlung, electron and neutron radiation sources. Custom designs are our specialty.
Small array for carbon total
stopping calorimeters |
Total Stopping Calorimeters
Total stopping calorimeters measure the total incident radiation.
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Carbon arrays for electron beams
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Soft x-ray total stopping calorimeters
Thin Foil Calorimeters
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Thin film calorimeters measure local dose in specific materials.
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Electron beam thinfoil calorimeters
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Bremsstrahlung calorimeters
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Neutron caliorimeters
Thermo-elastic Calorimeters
Thermoelectric calorimeters (TEC) measure fluence and deposition profiles in selected locations.
