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- An Overhauser magnetometer uses RF power to excite the electrons of a special chemical dissolved in the hydrogen-rich liquid. The electrons pass on their excited state to the hydrogen nuclei, altering their spin state populations, and polarizing the liquid, just like in a standard proton magnetometer but with much less power and to greater extent.
Actually, the total magnetization vector of the hydrogen liquid is larger in an Overhauser magnetometer, which allows sensitivity to be improved as well. Also, since the liquid can be polarized while the signal is being measured, Overhauser magnetometers have a much higher speed of cycling and sensitivity than standard proton precession magnetometers.
Overhauser magnetometers are without question the most energy efficient magnetometers available with sensitivities suitable for Earth field measurement. Power consumption can be optimized to be as low as 1W for continuous operation, yielding sensitivities between 0.1nT to 0.01nT, and sampling rates as high as 5Hz. Also, no warm up time is required, so for slow reading rates, the sensor can be shut down to save power. Continuous Overhauser magnetometers, like the GSM-19 or GSM-11, operate with continuous polarization, and offer sampling rates up to 10Hz, but require more power (few watts) to operate.
Information obtained from http://www.gemsys.ca/index.htm
Group: Instrument_Details
Entry_ID: OVM
Group: Instrument_Identification
Instrument_Category: Earth Remote Sensing Instruments
Instrument_Class: Passive Remote Sensing
Instrument_Type: Magnetic Field/Electric Field Instruments
Short_Name: OVM
Long_Name: Overhauser Scalar Magnetometer
End_Group
Online_Resource: http://www.gemsys.ca/index.htm
Creation_Date: 2008-07-18
End_Group
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