Phase-locked yttrium iron garnet magnetometer for remote measurement of small field changes in a fluctuating background

Journal Article · Wed Sep 01 04:00:00 EDT 1982 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1137178· OSTI ID:5037876

Carpenter, K H; da Silva, M K

The ferromagnetic resonance frequency in small yttrium iron garnet (YIG) spheres placed in a rf filter structure is used to measure small changes in large magnetic fields in the presence of high-level random fluctuations of the background field. (Such measurements are needed for fusion plasma diagnostics.) This YIG magnetometer probe is driven by a microwave network analyzer whose working frequency is phase locked to the probe resonance, yielding an output frequency that is linearly related to the magnetic field magnitude. The YIG filter's phase response is used to control the system frequency, allowing measurement resolutions almost two orders of magnitude better than the YIG resonance 3 dB linewidth. Noise is effectively removed by the phase lock circuitry's low cut-off frequency and by time averaging using a frequency counter. Accuracy is essentially limited by the uncertainty in determining the constants in the linear field-frequency equation and by maintenance of constant temperature and magnetic field direction during incremental measurements.

• Research Organization: Department of Electrical Engineering, University of Missouri-Rolla, Rolla, Missouri 65401
• OSTI ID: 5037876
• Journal Information: Rev. Sci. Instrum.; (United States), Journal Name: Rev. Sci. Instrum.; (United States) Vol. 53:9; ISSN RSINA
• Country of Publication: United States
• Language: English

Related Subjects

440300* -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
ACCURACY
CONTROL
FERRITE GARNETS
FERROMAGNETIC RESONANCE
FILTERS
FREQUENCY CONTROL
FUNCTIONS
MAGNETIC FIELDS
MAGNETIC RESONANCE
MAGNETOMETERS
MEASURING INSTRUMENTS
MINERALS
NOISE
PLASMA DIAGNOSTICS
PROBES
REMOTE SENSING
RESONANCE
RESPONSE FUNCTIONS
RF SYSTEMS
SILICATE MINERALS
SPHERES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VARIATIONS
YTTRIUM COMPOUNDS