NEW VECTOR NEW VECTOR MAGNETOMETER IN MAGNETOMETER IN

OBSERVATORY PRACTICEOBSERVATORY PRACTICE

L. Hegymegi,L. Hegymegi,11 J. Szöllősy, J. Szöllősy,22 L. Merényi, L. Merényi,33 L. L. SzabadosSzabados33

11MinGeo – MinGeo – 22Araconsys – Araconsys – 33Eötvös L. Geophysical InstituteEötvös L. Geophysical InstituteBudapest, HungaryBudapest, Hungary

XIVth IAGA Workshop on Geomagnetic Observatory Instruments, Data XIVth IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition and Processing, Changchun Magnetic Observatory, China,Acquisition and Processing, Changchun Magnetic Observatory, China,

September 13 - 23, 2010

Fluxset magnetometerFluxset magnetometer

► vector magnetometer with vector magnetometer with analog output signalanalog output signal

► full field magnetometerfull field magnetometer► simple construction and simple construction and

operationoperation► small sizesmall size► low power consumptionlow power consumption

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Main features:

Fluxset sensorFluxset sensor

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

• Magnetic core is saturated periodically Minimizes the memory effect

• Sensor response phase-modulated Higher signal/noise ratio

• Theoretically linear No field feedback is necessary

• Not the actual shape of the B-H curve utilizedHigh reliability and wide operating temperature

range• No cross-talk or cross-field effect

Fluxset sensorFluxset sensor

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

5mm

Metallic glass ribbon Pick-up coil Driving coil

Coil holder

SensitivitySensitivity

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

0 500 1000 1500 2000 2500 3000-100

-90

-80

-70

-60

-50

-40

-30

-20

-10(100T = 0dB)

Sig

na

l pk [

dB

]

Frequency [Hz]

Gain and performance testGain and performance test

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

-2 0 0 -1 0 0 0 1 0 0 2 0 0

3 5

4 0

4 5

Ma

gn

eti

c

fie

ld

[

T]

T e m p e ra tu re [ o C ]

AdvantagesAdvantages

►Small size (~5 mm)►Low power consumption (~4mW)►Good temperature stability►Full-field magnetometer►Good resolution►No Barkhausen noise►Good experience in production

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

DisadvantagesDisadvantages

►Not yet experience in long-term Not yet experience in long-term stabilitystability

►Not yet experience in low field/low Not yet experience in low field/low noise applications (geomagnetic field noise applications (geomagnetic field range)range)

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Different models of Fluxset Different models of Fluxset magnetometermagnetometer

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

AwardAward

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Experimental setup in THYExperimental setup in THY

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

SERVER/INTERNET

MAGREC-4

24 bit A/D

Fluxset T2-10 Thermometer

GPS

Bartington MAG 01H

Experimental setup in THYExperimental setup in THY

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

First resultsFirst results

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

MAG 01H

FXS T2-10

DMI FGE

temperature

27/8/10

Y component

First resultsFirst results

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Future application plansFuture application plans

►Combined observatory magnetometer Combined observatory magnetometer (dIdD + FXS) for fast magnetic (dIdD + FXS) for fast magnetic recording (1 Hz) with good baseline recording (1 Hz) with good baseline stabilitystability

►D/I theodolite equipped with three D/I theodolite equipped with three component FXScomponent FXS

►Field instrument for magnetic surveyField instrument for magnetic survey►Gradiometer for magnetic surveyGradiometer for magnetic survey

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Software for calulation of Software for calulation of magnetic vector data in a magnetic vector data in a

combined systemcombined system

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

dIDD magnetometer:dIDD magnetometer: slow but measures full-field, with good slow but measures full-field, with good baseline stabilitybaseline stabilityfluxset or fluxgate magnetometer:fluxset or fluxgate magnetometer: faster, but can have lower faster, but can have lower baseline stability baseline stability The fast magnetometer XYZ/HDZ data are continously re-The fast magnetometer XYZ/HDZ data are continously re-calibrated with dIdD magnetometer XYZ/HDZ data using the last calibrated with dIdD magnetometer XYZ/HDZ data using the last several minutes or hours recording (either raw data or minute several minutes or hours recording (either raw data or minute averages). averages). For For XX component: component: mxmx and and aa are continousely recalculated using are continousely recalculated using linear regression:linear regression:

Xfast = XdIdD Xfast = XdIdD ** mx + a mx + aChange of Change of mm and and aa can reflect temperature dependence of the can reflect temperature dependence of the magnetometer. magnetometer. The method built into the data acquisition program. The procedure The method built into the data acquisition program. The procedure is tested and now we have to find the optimal calibration period is tested and now we have to find the optimal calibration period and get long-term experience with the method.and get long-term experience with the method.

ConclusionsConclusions

►More time needed for the experimentsMore time needed for the experiments►Industrial version needs more Industrial version needs more

modification/ improvements for modification/ improvements for geomagnetic applicationsgeomagnetic applications

►It seems to be possible to reduce the It seems to be possible to reduce the noise as its main source is in the noise as its main source is in the electronicselectronics

►Because of its simplicity, small size and Because of its simplicity, small size and low power consumption it is promisinglow power consumption it is promising

XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010