Title: NIST Develops Advanced Johnson Noise Thermometry Methods
1. Summary:
NIST has developed advanced Johnson noise thermometry (JNT) methods that utilize quantum voltage noise sources (QVNS) to measure temperature with high accuracy. These methods link measured thermal voltage fluctuations directly to electrical units via the AC Josephson Voltage Standard, providing key advantages for temperature scale metrology and extending JNT’s practical application range.
2. Key Points:
– JNT measures thermal fluctuations in conductors using QVNS
– New NIST methods link measurements to AC Josephson Voltage Standard
– Provides independent data for validating the International Temperature Scale of 1990 (ITS-90) in overlapping temperature ranges
– Utilizes wide-band spectral analysis, digital signal processing, and pulse-quantized voltage synthesis
– Balances QVNS noise power with thermally generated Johnson noise for absolute and relative temperature measurements
3. Impact:
– Advances application of JNT in demanding environments like high-temperature nuclear reactors
– Provides independent data for validating ITS-90 in overlapping temperature ranges
– Offers more flexibility and functionality compared to conventional JNT methods
4. Implementation:
– Current status: NIST-developed spectral JNT methods are under review
– Expected impacts: Advancing JNT applications in new environments
– Implementation timeframe: Not specified in the article
Source: https://www.nist.gov/programs-projects/johnson-noise-thermometry
Keywords: Thermometry, Temperature, Noise, Metrology, Standards
