Cryogenic Temperature SensorsFrom Lake Shore Cryotronics
The choice of the right temperature sensor is essential for an accurate and realistic determination of low temperatures in a cryostat. For this purpose, each sensor can be attributed with an individual set of properties, like temperature range, accuracy and resolution, magnetic resilience, radiation resilience and package options. We are offering Cernox, Silicon Diodes, Gallium Aluminum Arsenide (GaAlAs) Diodes, Germanium, ROx, Platinum, Capacitance and Thermocouple temperature sensors. Depending on the sensor type, different packages are available, like specially designed, bare chips, bolt-down and embedded packages.Features
- 0.01K to 1543 K temperature range
- Excellent magnetic field performance
- Good Radiation resistance
- High vacuum compatible
|Temperature range||Standard curve||Below 1 K||Can be used in radiation||Performance in magnetic field|
|Negative Temperature Coefficent RTDs|
|Cernox®||0.10 K to 420 K||■||■||Excellent above 1 K|
|Germanium||0.05 K to 100 K||■||■||Not recommended|
|Ultra-low temperature Rox™||<0.01 K to 40 K||■||■||■||Good below 1 K*|
|Interchangeable Rox™||0.05 K to 40 K||■||■||■||Good below 1 K*|
|Silicon||1.4 K to 500 K||■||Fair above 60 K|
|GaAlAs||1.4 K to 500 K||Fair|
|Positive Temperature Coefficient RTDs|
|Platinum||14 K to 873 K||■||■||Fair above 30 K|
|Capacitance||1.4 K to 290 K||Excellent|
|Thermocouple Wire||1.2 K to 1543 K||■||Fair|
|HR Series||20 K to 420 K||■|
- Thin film resistance cryogenic temperature sensor
- Non-magnetic packages
- Temporarily unavailable – please consider Cernox as an alternative.
- resistance temperature sensors
- “Secondary Standard Thermometer”
- High sensitivity at submillikelvin temperatures
- calibrations down to 10 mK available
- Dilution refrigerator applications
- Optical shielding improves sensor thermal stability
- RX-102A, RX202A and RX-103A
- Standard curve interchangeable
- Good radiation resistance
- Low magnetic field-induced errors
- DT-670-SD, DT-670E-BR and DT-621-HR
- Best accuracy across the widest useful temperature range of any silicon diode
- minimized sensor self-heating
- Conformance to standard Curve DT-670 temperature response curve
- Monotonic temperature response
- Excellent sensitivity (dV/dT) at temperatures below 50 K
- Conforms to IEC 751 standards down to 70 K
- High reproducibility: ±5 mK at 77 K
- SoftCal™ calibration available
- Non-magnetic packages available (all PT-102 and PT-103 variants)
- Capable of mK control stability in the presence of strong magnetic fields
- Monotonic in C versus T to nearly room temperature
- Type E (Chromel-Constantan)
- Type K (Chromel-Alumel)
- 15 years of full material traceability
- Resistance and sensitivity data
- Gain confidence from our test protocol
Temperature is a thermodynamic quantity that describes the state of a body. To measure this state, a second body can be brought into contact with the first. This causes the temperature in both bodies to equalize after a certain period.
Thermodynamically, the difference between the temperature of two bodies can always be determined. From this the temperature scale was developed, which refers to the absolute zero point. In the SI system this is the Kelvin scale, which is measured in Kelvin [K] (see box for further scales). Fixed points of this scale are so-called triple points. At these points an atomic species or a compound like water (H2O) is simultaneously present in all three aggregate states, i.e. solid, liquid and gaseous. This is the case for water at 273.16 K. This point is assigned to exactly one pressure and one temperature. The boiling temperature of water (temperature at the transition from liquid to gaseous) varies depending on the pressure and is therefore not clearly defined.
Temperature Conversion Formulas
- degrees Celsius T[°C] = T[K]-273.15
- degrees Fahrenheit T[°F] = T[°C] x 1.8+32
- Degree Rankine T[°R] = T[K] x 1.8
- Degree Réaumur T[°Ré] = (T[K] - 273.15) x 0.8
Thermometers are used to measure the temperature. These are measuring instruments whose measurable data output changes with temperature in a reproducible manner. In general, a distinction is made between primary and secondary thermometers. A primary thermometer is characterized by the fact that its dependence on temperature can be described without unknown and temperature-dependent variables. For example, gas thermometers, acoustic thermometers, noise thermometers and total radiation pyrometers. A secondary thermometer outputs a value that must be calibrated using fixed temperature points. The Platinum RTD (Resistance Temperature Detector) is an example of a secondary thermometer and is based on the change in the electrical resistance of a platinum wire as a function of temperature.
Since primary thermometers are large, slow and expensive, secondary thermometers are used almost exclusively in practice. The secondary thermometers are calibrated using international standards and fixed temperature points. These are defined in IST-90 (International Temperature Scale of 1990) and PLTS-2000 (Provisional Low Temperature Scale of 2000).
Responsible for defining the temperature scale are government authorities such as NIST (National Institute of Standards and Technology), NPL (National Physical Laboratory) and PTB (Physikalisch-Technische Bundesanstalt).
For temperature sensors with extremely reproducible manufacturing processes, tolerance curves are created that indicate how close the temperature curve obtained is to the calibration standard. Examples are Si diodes and platinum thermometers, where it is possible to exchange individual sensors of the same design and still achieve an accurate measurement of the temperature. The degree of accuracy is determined by tolerance bands.
The different temperature sensors (silicon diodes, platinum RTDs and NTC temperature sensors) can be read out by means of a temperature monitor. The temperature controllers go one step further, where the temperature is measured by means of a temperature sensor and then actively set to the desired value by means of an additional heater.
High end applications for the HR series are among others, space telescopes, supercolliders, fusion reactors, research satellites and maglev locomotives.