Johnson noise thermometer for high radiation and high temperature environments
The purpose of development work on the Johnson noise power thermometer (JNPT) was to apply the work of Nyquist, who showed that the mean-squared noise voltage spectrum appearing across an unloaded resistor of value R is given by anti e/sub n//sup 2/ = 4hfR/(exp (hf/kT) - 1)) where anti e/sub n//sup 2/ has the units volts squared per unit frequency, and h and k are the Planck and Boltzmann constants, respectively, f is the frequency in hertz (Hz) and T is the absolute temperature in kelvins (K). J.B. Johnson showed that the noise was independent of the composition of the resistor. These discoveries gave rise to a temperature measurement technique using the Johnson noise voltage and Johnson noise current in a noise power mode, which essentially gives immunity to the decalibrating effects of radiation-induced transmutations of the temperature-sensing element. Experiments have been conducted in which temperature measurements were made in the range from 300 to 1200/sup 0/K. Extrapolation of plots of these data pass through absolute zero, as expected. In-pile irradiation experiments show no perceptible decalibration after 4500 h in high neutron flux even though 80% of the original sensor material, rhenium, had been transmuted to osmium.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5655830
- Report Number(s):
- CONF-880122-5; ON: DE88003770
- Resource Relation:
- Conference: 5. symposium on space nuclear power systems, Albuquerque, NM, USA, 11 Jan 1988; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NOISE THERMOMETERS
PERFORMANCE TESTING
ACCURACY
AVAILABILITY
CALIBRATION
FEASIBILITY STUDIES
HFIR REACTOR
NEUTRON FLUX
OSMIUM
PHYSICAL RADIATION EFFECTS
RELIABILITY
RHENIUM
SERVICE LIFE
TRANSMUTATION
USES
ELEMENTS
ENRICHED URANIUM REACTORS
IN CORE INSTRUMENTS
IRRADIATION REACTORS
ISOTOPE PRODUCTION REACTORS
MEASURING INSTRUMENTS
METALS
PLATINUM METALS
RADIATION EFFECTS
RADIATION FLUX
REACTOR INSTRUMENTATION
REACTORS
RESEARCH AND TEST REACTORS
RESEARCH REACTORS
TANK TYPE REACTORS
TEST REACTORS
TESTING
THERMAL REACTORS
THERMOMETERS
TRANSITION ELEMENTS
WATER COOLED REACTORS
WATER MODERATED REACTORS
440300* - Miscellaneous Instruments- (-1989)