Cryogenic Temperature Sensors Research Articles

A standardized Cernox™ cryogenic temperature sensor for aerospace applications

The success of any aerospace mission depends upon the reliability of the discrete components comprising the instrument. To this end, many test standards have been developed to define test protocols and methods for the parts used in these missions. To date, no recognized MIL-type standard exists for cryogenic temperature sensors that are used from room temperature to 20K or below. The aerospace applications utilizing these sensors require the procuring entity to develop a specification which the sensor manufacturer uses to screen and qualify a single build lot for flight use. The individual applications often require only a small number of sensors with the end result being a relatively high cost and long delivery time. Over the past two decades, Lake Shore Cryotronics, Inc. has worked with many aerospace companies to supply Cernox™ cryogenic temperature sensors for numerous missions. The experience gained from this work has led to the development of a manufacturing and test protocol resulting in “off-the-shelf” cryogenic temperature sensors that should meet the requirements for many aerospace applications. Sensors will be available at the base part level with the ability to configure the delivered part with regard to lead wire material, package adapter, lead wire extensions, and calibration as appropriate or necessary for the application. This work presents details of this manufacturing, inspection, and test protocol as well as performance characteristics of Cernox™ temperature sensors when inspected and tested to this protocol.

Negative thermal expansion in a zirconium tungstate/epoxy composite at low temperatures

We have investigated a composite of cubic α-ZrW2O8 and epoxy with a high ceramic loading for its thermal expansion properties at cryogenic temperatures. The composite was fabricated by allowing the ceramic to sediment in the epoxy resin before curing, using only the dense bottom fraction of the composite for further measurements. Density measurements and thermogravimetric analysis showed that the samples repeatably consisted of approximately 60 vol% tungstate without significant voids. The coefficient of thermal expansion was measured by dilatometry at temperatures from 25 to 300 K, and we found negative thermal expansion occurring at temperatures below about 100 K. The observed behavior is consistent with predictions produced by a variational model, which shows that the high ceramic loading is necessary to reliably achieve negative thermal expansion in the composite. The composite has potential applications as compensators for unwanted thermal expansion at low temperatures and for fiber-optic cryogenic temperature sensors.

Focus on semiconductors and software

Focus on semiconductors and software

A Reflective Photonic Crystal Fiber Temperature Sensor Probe Based on Infiltration with Liquid Mixtures

In this paper, a reflective photonic crystal fiber (PCF) sensor probe for temperature measurement has been demonstrated both theoretically and experimentally. The performance of the device depends on the intensity modulation of the optical signal by liquid mixtures infiltrated into the air holes of commercial LMA-8 PCFs. The effective mode field area and the confinement loss of the probe are both proved highly temperature-dependent based on the finite element method (FEM). The experimental results show that the reflected power exhibits a linear response with a temperature sensitivity of about 1 dB/°C. The sensor probe presents a tunable temperature sensitive range due to the concentration of the mixture components. Further research illustrates that with appropriate mixtures of liquids, the probe could be developed as a cryogenic temperature sensor. The temperature sensitivity is about 0.75 dB/°C. Such a configuration is promising for a portable, low-power and all-in-fiber device for temperature or refractive index monitoring in chemical or biosensing applications.

Le porocarcinome : étude anatomoclinique de quatre cas

Experimental and numerical studies have been conducted with the aim of modeling pressure rises which occur in the helium, during quenches of the 11.7-T superconducting magnet named Iseult. Iseult is based on a double-pancake winding internally cooled by superfluid helium channels opening into a pressurized He II bath at 1.8 K. A scale mock-up has been built of 10 copper equivalent pancake slices and 7 helium channels per pancake. The heat produced by a quench of the Iseult magnet is simulated by electrical heaters put inside each copper plate. Cryogenic pressure and temperature sensors have been fitted in the helium channels and in the bath. Bath pressure measurements are given for various heating powers, various numbers of heated plates and various bath volumes. Comparisons with a simple numerical model permit to identify the main physical mechanisms which drive the pressure rise during a quench.

극저온 냉동기를 이용한 온도센서 교정시스템 개발

극저온시스템에서는 측정하려는 온도의 범위, 온도센서의 형상 및 정확도 등을 고려하여 온도센서를 선택하여 사용한다. 이 중 온도센서의 정확도는 실험 신뢰성의 매우 중요한 요소이다. 극저온용 온도센서의 교정을 위해서 2단 극저온냉동기를 이용하여 시스템을 개발하였다. 극저온냉동기의 1단부에 열 차폐층을 설치하고 MLI(Multiple layer insulation)을 이용하여 외부로 부터의 열 침입을 최소화 하였다. 그리고 시간과 비용의 절약을 위해 동시에 다수의 온도센서를 교정하기 위한 센서홀더를 개발하여 20개 이상의 센서를 동시에 교정할 수 있도록 하였다. 또한 히터를 사용하여 온도조절을 통해 다양한 온도에서의 온도교정이 가능하도록 하였다. 본 논문에서는 온도센서 교정시스템의 설계 및 제작 그리고 대표적인 온도 교정 실험 결과를 소개한다.

Focus on vacuum and cryogenics

Focus on vacuum and cryogenics

Helium Pressure Increase During a Quench of the Iseult Coil

An experimental model has been studied to predict the pressure rise in the Iseult coil during a quench. The model is built of 10 copper equivalent pancake slices and 7 helium channels per pancake. The heat produced by a quench of the Iseult magnet is simulated by electrical heaters put inside each copper plate. Cryogenic pressure and temperature sensors have been fitted in the helium channels and in the bath. The model is cooled by pressurized superfluid helium at 1.8 K. Bath pressure measurements are given for various heating powers and various numbers of heated plates. A scaling law is put forward to extrapolate the model results to the Iseult pressure rise during a quench. Then the hydraulic circuit is numerically simulated to verify the efficiency of the quench valves to limit the pressure to 0.4 MPa.

Experimental simulation of helium pressure rise during a quench of a superconducting coil cooled by a superfluid helium bath

Experimental and numerical studies have been conducted with the aim of modeling pressure rises which occur in the helium, during quenches of the 11.7-T superconducting magnet named Iseult. Iseult is based on a double-pancake winding internally cooled by superfluid helium channels opening into a pressurized He II bath at 1.8K. A scale mock-up has been built of 10 copper equivalent pancake slices and 7 helium channels per pancake. The heat produced by a quench of the Iseult magnet is simulated by electrical heaters put inside each copper plate. Cryogenic pressure and temperature sensors have been fitted in the helium channels and in the bath. Bath pressure measurements are given for various heating powers, various numbers of heated plates and various bath volumes. Comparisons with a simple numerical model permit to identify the main physical mechanisms which drive the pressure rise during a quench.

Electrical Properties of Cr–N Films Deposited by Sputtering: Application to Cryogenic Temperature Sensors

The electrical properties of chrome nitride (Cr–N) films have been investigated for application to cryogenic temperature sensors. The films were deposited on silica substrates by RF magnetron sputtering under various total pressures without substrate heating. The electrical resistivity at room temperature increased from 1.4×10-3–1.7×10-3 to 3.4×10-3–4.0×10-3 Ω cm as the total pressure increased. X-ray diffraction measurements revealed that the crystallinity was improved in the high-total-pressure region. The temperature dependence of the electrical resistivity for Cr–N films exhibited semiconducting behavior. The slope of the electrical resistivity versus temperature increased with increasing total pressure. When a magnetic field was applied parallel to the current direction, the change in magnetoresistance at 3.7 K for Cr–N films was less than 1% in the range of 0 to 10 T. The results indicated that temperature sensors made of Cr–N films are available in high magnetic fields.

Electrical Properties of Cr–N Films Deposited by Sputtering: Application to Cryogenic Temperature Sensors

Electrical Properties of Cr–N Films Deposited by Sputtering: Application to Cryogenic Temperature Sensors

Focus on vacuum and cryogenics

Focus on vacuum and cryogenics

Thin film temperature sensor for cryogenic region with small magnetoresistance

Chromium nitride (CrN) thin films were fabricated onto Si wafers by RF magnetron sputtering equipment in pure N 2 gas. By adjusting the fabrication conditions, the film had negative temperature coefficient of resistance (TCR) below 300 K. It showed reasonable sensitivity between 300 and 1.8 K. The temperature resolution in the cryogenic temperature region was better than 1 mK. A good thermal cycle stability was observed. After 27 thermal cycles between 4 and 300 K, the coefficient of variation (CV) value was as small as 0.098% at 4 K, which corresponds to a 2.1 mK temperature shift. In addition, the thermometer was nearly insensitive to the magnetic field. The temperature shift due to magnetoresistance in a magnetic field of 9 T was less than 5 mK at 4 and 2 K. Therefore CrN can be an excellent choice of material for cryogenic temperature sensors under magnetic fields.

Investigations on printed elastic resistors containing carbon nanotubes

This paper presents the results of authors investigations on elaboration of a new thick film composition filled with carbon nanotubes (CNTs). The polymer composition consists of polymer vehicle, which is the solution of organic resin in certain combination of solvents, and functional phase—carbon nanotubes well dispersed in the vehicle. The pastes were applied with screen-printing on several substrates and temperature cured. The properties of obtained layers were characterized. Series of samples were prepared with different amount of CNTs to evaluate electrical properties. Changes in resistance were investigated during periodic mechanical and temperature stresses, realized through cyclical bending and rapid temperature change. Tensometric effect was also investigated. Investigations have proved that polymer composites based on carbon nanotubes exhibit high resilience to stress factors. Resistance change in function of temperature was also investigated to evaluate temperature coefficient of resistance (TCR). All this aspects are important for elastic resistors fabrication in printed electronics microcircuits. Resistance and noise measurements in cryostats have also been involved. 1/f type noise has been observed. Noise intensity, calculated in decade frequency bands, rises significantly with increasing temperature. Activation energies of thermally activated noise sources (TANS) have been revealed using low-frequency noise spectroscopy. Relatively large value of negative TCR has been obtained from resistance versus temperature curve. Calculated dimensionless sensitivity is similar to that observed in cryogenic temperature sensors. However, bulk noise intensity of resistive layer is larger than obtained for lead containing RuO2 based resistive layers.

Common rectifier diodes in temperature measurement applications below 50 K

In this paper we studied the use of common electronic semiconductor diodes in temperature measurements at cryogenic atmosphere. The motivation for this is the high price of calibrated cryogenic temperature sensors since there are some applications, like quench detection, in which a cheaper and a less accurate sensor would suffice. We measured the forward voltage as a function of temperature, Vf(T), of several silicon rectifier diodes to determine the accuracy and interchangeability of the diodes. The experimental results confimed that Vf(T) of common rectifier diodes are similar to cryogenic sensor diodes, but the variability between two samples is much larger. The interchangeability of the diodes proved to be poor if absolute temperatures are to be measured. However for sensing changes in temperature they proved to be adequate and thus can be used to measure e.g. quench propagation or sense quench ignition at multiple locations with cheap price.

Fabrication and test a 600 kJ SMES model coil

A small SMES system and a 600kJ SMES model coil were fabricated. High temperature superconducting (HTS) wire which was reinforced with stainless steel was used for winding the model coil and its critical current was 624A at self-field and 20K. The type of model coil is double pancake coil (DPC). The number of turns of a DPC is 282 and length of HTS wire per DPC is about 220m. A two stage GM cryo-cooler (RDK-408) was used for cool down the SMES system and mounted in the middle of the top plate of a cryostat which has 580mm outer diameter. Cooling plates for conduction cooling were placed on top and bottom of DPC. Operating temperature of the system is 20K. Cryogenic temperature sensors (Cernox, SD type) were attached on the surface of a copper cylinder block for cool down test of the system. Temperature control test by a heat load also carried out.

English

This paper describes the different cryogenic temperature sensors used at cryogenictemperatures down to 1 K. The characteristics of these temperature sensors have been discussedin detail with their operating range, sensitivity, and accuracy. Other properties likeinterchangeability, effect of thermal cycling, effect of ionizing radiation ( neutron or gamma ray),effect of magnetic field has also been described. It is extremely important to choose the righttemperature sensor for right kind of application in a specific operating environment. This papergives an overview of some of the most widely used cryogenic temperature sensors.

Irradiation of cryogenic temperature sensors by gamma dose of 1 MGy

This article presents results of investigations of the cryogenic thermometers which can operate under high radiation environment. To clarify the temperature shifts due to gamma irradiation up to 1 MGy, the platinum (two types), carbon-glass, and TVO temperature sensors have been tested. Before the irradiation run, the selected sensors were calibrated and a series of experiments was carried out under irradiation of the sensors at 77.3 and 293 K when their readings were taken in situ. Afterwards, the postirradiation evolution (short and long time) of the sensors was measured at 4.2, 77.3, and 293 K. The results, depending on the type of the sensor, can be optimistic or pessimistic. Some comparisons with analogous data for fast neutron treatment have also been made.

Ruthenium oxide cryogenic temperature sensors

RuO 2 based cryogenic temperature sensors were developed using a nanopowder approach. Ruthenium oxide nanopowders were consolidated into compacts using the Plasma Pressure Compaction (P 2C ®) process and were tested for resistivity as a function of temperature for determining the reproducibility and stability of the sensors due to thermal stresses. The sensors showed metallic behavior and strong positive temperature coefficient of resistivity (PTCR). Resistance–temperature calibration demonstrated a monotonic response with a positive temperature coefficient of resistivity from 70 to 300 K along with dimensionless sensitivity (approximately 1.0) comparable to that of platinum resistance thermometers.

Radiation Effects on Cryogenic Temperature Sensors of Cernox, CGR and PtCo

Irradiation tests have been carried out in view of selecting the cryogenic temperature sensors for use in the RIKEN Superconducting Ring Cyclotron (SRC). About 300 temperature sensors will be installed, and most of them will be exposed to high radiation doses during the operation of accelerator. Those cryogenic temperature sensors, Cernox/spl trade/, CGR and PtCo, at room temperature were bombarded by the intense 210 MeV proton beam at the RIKEN Accelerator Research Facility (RARF) of RIKEN.