High Temperature Anisotropic Magnetoresistive (AMR) Sensors

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000236-000243
Author(s):  
Bharat B. Pant ◽  
Lucky Withanawasam ◽  
Mike Bohlinger ◽  
Mark Larson ◽  
Bruce W. Ohme
Keyword(s):  
High Temperature ◽  
Transfer Function ◽  
Bias Voltage ◽  
Room Temperature ◽  
Closed Loop ◽  
Low Frequency ◽  
Low Noise ◽  
Noise Characteristics ◽  
Thermal Chamber ◽  
Increasing Temperature

Magnetic field sensors are employed in down-hole oil, gas, and geothermal well-drilling applications for azimuth sensing, orientation/rotation sensing, and magnetic anomaly detection. Key requirements of these applications include high measurement accuracy in the near-DC frequency regime, high-operating temperatures, high mechanical shock and vibration, and severe size constraints. Silicon manufacturing processes enable the development of rugged components with small size compatible with assembly processes used for adjacent electronics in hermetically sealed hybrid and/or ceramic packages. Silicon-based magnetic sensors include Anistotropic Magnetoresistive (AMR), Giant Magnetoresistive (GMR) and Tunnelling Magnetoresistive (TMR) sensors. Commercially available GMR and TMR sensors generally cannot be operated much above 150°C. While GMR and TMR have enabled great areal density growth for magnetic recording industry over the past two decades, AMR sensors provide high accuracy measurements in the near-DC regime above 150°C. This is in part due to simplicity of their construction, but also due to their low noise characteristics at low frequencies compared to GMR and TMR. This paper will describe the extension of Honeywell's low noise AMR sensors into high temperature regime up to 225°C. Sensors being reported have room temperature bridge resistance of ~700 Ω, open loop sensitivity of ~2.5 mV/V-Gauss, with a temperature coefficient of sensitivity of −2500 ppm/°C. The low-frequency minimum detectable field monotonically increases with increasing temperature. At room temperature it is ~2.2 μG/√Hz@1 Hz and reaches a value of ~26μG/√Hz@1 Hz at 225°C. Signal and noise density both increase with increasing sensor bias voltage such that low-frequency signal-to-noise ratio does not vary in the bias voltage range of 2.5 V to 10V. These sensors have also been configured in a closed loop format using low noise electronics. Measurements of closed loop transfer function in the range of ±0.8 Gauss were made. The sensor was placed in a thermal chamber while the feedback electronics were placed outside at room temperature. The linearity of the transfer function is quite excellent; deviation from linearity increases monotonically with increasing temperature reaching < 0.002% of full scale or 29 μGauss at 225°C. Closed loop operation of a typical sensor shows 1-σ measurement variability of 21 μGauss at 220°C. By a combination of averaging and closed loop operation an input step from 0 to 75 μGauss is replicated at the output to within 0.1 μG at 225°C.

High-Temperature Anisotropic Magnetoresistive (AMR) Sensors

2015 ◽  
Vol 12 (4) ◽  
pp. 205-211 ◽  
Author(s):  
Bharat B. Pant ◽  
Lucky Withanawasam ◽  
Mike Bohlinger ◽  
Mark Larson ◽  
Bruce W. Ohme
Keyword(s):  
Bias Voltage ◽  
Closed Loop ◽  
Oil And Gas ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Low Noise ◽  
Measurement Variability ◽  
Magnetic Field Sensors ◽  
Voltage Range ◽  
Increasing Temperature

Magnetic field sensors are employed in downhole oil and gas well drilling applications for azimuth sensing, orientation/rotation sensing, and magnetic anomaly detection. As the wells get deeper there is demand from industry to increase the operating temperature from ~175°C to ~225°C and higher. We have extended the operating regimen of silicon-based anisotropic magnetoresistive sensors to higher temperatures to address this demand. The low-frequency minimum detectable field of these sensors monotonically increases with increasing temperature. At room temperature it is 2.2 μG/√Hz@1 Hz reaching a value of 26 μG/√Hz@1 Hz at 225°C. Signal and noise density both increase with increasing sensor bias voltage such that low-frequency signal-to-noise ratio does not vary in the bias voltage range of 2.5–10 V. We achieve excellent linearity of transfer function in the ±0.8 Gauss range in a closed-loop configuration. Deviation from linearity increases monotonically with increasing temperature but remains <0.002% of full scale or 29 μGauss at 225°C. Using low-noise electronics, closed loop operation of a typical sensor shows 1 – σ measurement variability of 21 μGauss at 220°C. By a combination of averaging and closed-loop operation, an input step from 0 to 75 μGauss is replicated at the output to within 0.1 μGauss at 225°C. Initial measurements suggest survivability of these sensors at 225°C to 2,000 h.

Purification of Eucalyptus globulus water prehydrolyzates using the HiTAC process (high-temperature adsorption on activated charcoal)

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Jenny Sabrina Gütsch ◽  
Herbert Sixta
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Adsorption Process ◽  
Value Added ◽  
Sustainable Utilization ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Charcoal Adsorption ◽  
Increasing Temperature ◽  
Value Added Products

Abstract The implementation of biorefinery concepts into existing pulp and paper mills is a key step for a sustainable utilization of the natural resource wood. Water prehydrolysis of wood is an interesting process for the recovery of xylo-oligosaccharides and derivatives thereof, while at the same time cellulose is preserved to a large extent for subsequent dissolving pulp production. The recovery of value-added products out of autohydrolyzates is frequently hindered by extensive lignin precipitation, especially at high temperatures. In this study, a new high-temperature adsorption process (HiTAC process) was developed, where lignin is removed directly after the autohydrolysis, which enables further processing of the autohydrolyzates. The suitability of activated charcoals as a selective adsorbent for lignin under process-relevant conditions (150 and 170°C) has not been considered up to now, because former experiments showed decreasing efficiency of charcoal adsorption of lignin with increasing temperature in the range 20–80°C. In contrast to these results, we demonstrated that the adsorption of lignin at 170°C directly after autohydrolysis is even more efficient than after cooling the hydrolyzate to room temperature. The formation of lignin precipitation and incrustations can thus be efficiently prevented by the HiTAC process. The carbohydrates in the autohydrolysis liquor remain unaffected over a wide charcoal concentration range and can be further processed to yield valuable products.

Effect of Temperature on Crater Formation and Ejecta Composition in Aluminum Alloy Targets

2012 ◽  
Vol 706-709 ◽  
pp. 768-773
Author(s):  
Masahiro Nishida ◽  
Koichi Hayashi ◽  
Junichi Nakagawa ◽  
Yoshitaka Ito
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Crater Formation ◽  
Influence Of Temperature ◽  
Gas Gun ◽  
Influence Of Temperature On ◽  
Increasing Temperature

The influence of temperature on crater formation and ejecta composition in thick aluminum alloy targets were investigated for impact velocities ranging from approximately 1.5 to 3.5 km/s using a two-stage light-gas gun. The diameter and depth of the crater increased with increasing temperature. The ejecta size at low temperature was slightly smaller than that at high temperature and room temperature. Temperature did not affect the size ratio of ejecta. The scatter diameter of the ejecta at high temperature was slightly smaller than those at low and room temperatures.

Study of a closed-loop high-precision front-end circuit for tunneling magneto-resistance sensors

2019 ◽  
Vol 33 (08) ◽  
pp. 1950085 ◽  
Author(s):  
Xiangyu Li ◽  
Jianping Hu ◽  
Xiaowei Liu
Keyword(s):  
High Precision ◽  
Closed Loop ◽  
Low Frequency ◽  
Cmos Technology ◽  
Low Noise ◽  
Corner Frequency ◽  
Cmos Process ◽  
Interface Circuit ◽  
Front End ◽  
Magneto Resistance

A closed-loop high-precision front-end interface circuit in a standard 0.35 [Formula: see text]m CMOS technology for a tunneling magneto-resistance (TMR) sensor is presented in this paper. In consideration of processing a low frequency and weak geomagnetic signal, a low-noise front-end detection circuit is proposed with chopper technique to eliminate the 1/f noise and offset of operational amplifier. A novel ripple suppression loop is proposed for eliminating the ripple in a tunneling magneto-resistance sensor interface circuit. Even harmonics is eliminated by fully differential structure. The interface is fabricated in a standard 0.35 [Formula: see text]m CMOS process and the active circuit area is about [Formula: see text]. The interface chip consumes 7 mW at a 5 V supply and the 1/f noise corner frequency is lower than 1 Hz. The interface circuit of TMR sensors can achieve a better noise level of [Formula: see text]. The ripple can be suppressed to less than 10 [Formula: see text]V by ripple suppression loop.

Low frequency damping and ultrasonic attenuation in Ti3Sn-based alloys

1994 ◽  
Vol 9 (6) ◽  
pp. 1441-1448 ◽  
Author(s):  
Catherine R. Wong ◽  
Robert L. Fleischer
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Ultrasonic Attenuation ◽  
Low Frequency ◽  
Basic Mechanism ◽  
Low Frequencies ◽  
High Frequencies ◽  
Young’S Moduli ◽  
High Temperature Alloys ◽  
Damping Behavior

Studies of high-temperature alloys in the Ti-Sn system based on the intermetallic compound Ti3Sn have identified alloys that damp strongly both at low frequencies (0.1 to 10 Hz) and high frequencies (5 to 20 MHz). The low frequency damping behavior shows loss factors as high as 0.04 at room temperature and Young's moduli that rise with temperature from 40 °C to 100 °C for two alloys. Although the basic mechanism or mechanisms of energy dissipation are presently unknown, the alloys are notable for unusual shapes of microhardness indentations. The deformations imply that large reversible strains can occur at temperatures from 23 °C to 1150 °C.

4H-SiC PIN Diode as High Temperature Multifunction Sensor

2017 ◽  
Vol 897 ◽  
pp. 630-633 ◽  
Author(s):  
Shuo Ben Hou ◽  
Per Erik Hellström ◽  
Carl Mikael Zetterling ◽  
Mikael Östling
Keyword(s):  
High Temperature ◽  
Bias Voltage ◽  
Temperature Sensitivity ◽  
Room Temperature ◽  
Optical Sensing ◽  
Temperature Sensing ◽  
The Other ◽  
Pin Diode ◽  
Forward Current

An in-house fabricated 4H-SiC PIN diode that has both optical sensing and temperature sensing functions from room temperature (RT) to 550 °C is presented. The two sensing functions can be simply converted from one to the other by switching the bias voltage on the diode. The optical responsivity of the diode at 365 nm is 31.8 mA/W at 550 °C. The temperature sensitivity of the diode is 2.7 mV/°C at the forward current of 1 μA.

Cuprate High Temperature Superconductors and the Vision for Room Temperature Superconductivity

SPIN ◽  
2017 ◽  
Vol 07 (02) ◽  
pp. 1750006 ◽  
Author(s):  
Dennis M. Newns ◽  
Glenn J. Martyna ◽  
Chang C. Tsuei
Keyword(s):  
High Temperature ◽  
High Frequency ◽  
Room Temperature ◽  
Phonon Frequency ◽  
High Temperature Superconductors ◽  
Low Frequency ◽  
Unconventional Superconductivity ◽  
Superconducting Transition ◽  
Strongly Coupled ◽  
Room Temperature Superconductivity

Superconducting transition temperatures of 164 K in cuprate high temperature superconductors (HTS) and recently 200 K in H3S under high pressure encourage us to believe that room temperature superconductivity (RTS) might be possible. In considering paths to RTS, we contrast conventional (BCS) SC, such as probably manifested by H3S, with the unconventional superconductivity (SC) in the cuprate HTS family. Turning to SC models, we show that in the presence of one or more van Hove singularities (vHs) near the Fermi level, SC mediated by classical phonons ([Formula: see text]phonon frequency) can occur. The phonon frequency in the standard [Formula: see text] formula is replaced by an electronic cutoff, enabling a much higher [Formula: see text] independent of phonon frequency. The resulting [Formula: see text] and isotope shift plot versus doping strongly resembles that seen experimentally in HTS. A more detailed theory of HTS, which involves mediation by classical phonons, satisfactorily reproduces the chief anomalous features characteristic of these materials. We propose that, while a path to RTS through an H3S-like scenario via strongly-coupled ultra-high frequency phonons is attractive, features perhaps unavailable at ordinary pressures, a route involving SC mediated by classical phonons which can be low frequency may be found.

scholarly journals Generation Recombination Noise in GaN Photoconducting Detectors

1999 ◽  
Vol 4 (S1) ◽  
pp. 817-822
Author(s):  
M. Misra ◽  
D. Doppalapudi ◽  
A.V. Sampath ◽  
T.D. Moustakas ◽  
P.H. McDonald
Keyword(s):  
Room Temperature ◽  
Low Frequency ◽  
Optical Excitation ◽  
Noise Spectrum ◽  
High Resistivity ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Characteristics ◽  
Deep Traps ◽  
Noise Measurements

Low frequency noise measurements are a powerful tool for detecting deep traps in semiconductor devices and investigating trapping-recombination mechanisms. We have performed low frequency noise measurements on a number of photoconducting detectors fabricated on autodoped n-GaN films grown by ECR-MBE. At room temperature, the noise spectrum is dominated by 1/f noise and thermal noise for low resistivity material and by generationrecombination (G-R) noise for high resistivity material. Noise characteristics were measured as a function of temperature in the 80K to 300K range. At temperatures below 150K, 1/f noise is dominant and at temperatures above 150K, G-R noise is dominant. Optical excitation revealed the presence of traps not observed in the dark, at room temperature.

The thermal expansion and high temperature transformation of SnS and SnSe*

1979 ◽  
Vol 149 (1-2) ◽  
Author(s):  
Heribert Wiedemeier ◽  
Frank J. Csillag
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Melting Point ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Orthorhombic Modification ◽  
Temperature Transformation ◽  
Increasing Temperature

AbstractThe thermal expansion of SnS and SnSe has been studied above room temperature up to the melting point of 1163 ± 5K and 1135 ± 5K, respectively, by X-ray diffraction techniques using a 190 mm Unicam high temperature camera. The changes of the lattice parameters indicate that the atomic positions in the (010) plane approach a square planar arrangement with increasing temperature. The transformation of SnS and SnSe from orthorhombic to a pseudotetragonal orthorhombic modification with

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