Tuned-circuit Johnson noise thermometry
- Tennessee Univ., Knoxville, TN (USA)
Three tuned circuits that can be used in Johnson noise thermometry have been analyzed; series resistance-inductance-capacitance (RLC), parallel RLC, and transformer coupled. Tuned circuits allow the temperature of the sensor to be determined by a single noise voltage, which is ideally independent of the resistance of the sensor, thereby reducing the complexity of temperature-measuring systems for space applications. Direct-coupled and transformer-coupled tuned circuits may offer advantage to the SP-100 system designer interfacing with data systems. A study was performed to establish whether the advantages of the ideal tuned circuits would be obtained with real, lossy inductive components and would provide a measurement system independent of aging and temperature effects on sensor resistance. Theoretical mean-squared output voltage dependence on sensor temperature and resistance, output capacitor value, and inductor temperature and resistance are derived for the series and parallel RLC cases. It is shown for tuned circuits using lossless inductors that the mean squared voltage is kT{sub R}/C, where T{sub R} is the sensor temperature and C is the capacitance of the capacitor. For lossy inductors and transformers, the mean-squared capacitor voltage is a function of sensor resistance, which may change in an unknown manner during an extended mission. Experiments were performed using a low-loss magnetic core as the core material of an inductor and also of a transformer. These results show that the effects of core loss on temperature accuracy are roughly the same in both cases. Experiments also show that for a sensor resistance of 100{Omega} at 1375K and for appropriate choices of inductance and capacitance values, the temperature measurement error due to an unknown sensor resistance change is in the range of 0.3 to 1 K/{Omega}, depending on the circuit used. 3 refs., 8 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- DOE/NE
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5412758
- Report Number(s):
- CONF-900109-5; ON: DE89016221
- Resource Relation:
- Conference: 7. symposium on space nuclear power systems, Albuquerque, NM (USA), 7-11 Jan 1990
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dual-mode self-validating resistance/Johnson noise thermometer system
Numerical studies on the transition of tuned substrate self-bias in a radio-frequency inductively coupled plasma
Related Subjects
42 ENGINEERING
NOISE THERMOMETERS
REMOTE SENSING
SPACE POWER REACTORS
TANK CIRCUITS
ELECTRONIC CIRCUITS
REACTOR COOLING SYSTEMS
COOLING SYSTEMS
ENERGY SYSTEMS
IN CORE INSTRUMENTS
MEASURING INSTRUMENTS
MOBILE REACTORS
POWER REACTORS
REACTOR COMPONENTS
REACTOR INSTRUMENTATION
REACTORS
THERMOMETERS
210600* - Power Reactors
Auxiliary
Mobile Package
& Transportable
426000 - Engineering- Components
Electron Devices & Circuits- (1990-)