definition, working principle, types, and use of magnetometer.

1. MAGNETOMETER
PRESENTED
BY
Ijaz Ul Haq
M Bilal younis
Moazam Ali
1

2. MAGNETOMETER
 Definition
Magnetometer are measurement instruments
used for two general purposes: to measure
the magnetization of a magnetic material like
a ferromagnet, or to measure the strength
and, in some cases, the direction of
the magnetic field at a point in space.
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3. OUTLINE
 Magnetometer data: what are we
measuring?
 Ground magnetic signatures of
 Earth’s magnetic field
 Ring currents
 Auroral currents
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4. MAGNETIC FIELD
MEASUREMENT
 magnetic field sensors can be divided into
two components
I. vector component
II. Scalar magnitude types.
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5. MAGNETIC FIELD FUNDAMENTALS
 The vector types can be further divided into
sensors that are used to measure low fields
(<1 mT) and high fields (>1 mT).
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6.  Instruments that measure low fields are
commonly called magnetometers
 High-field instruments are usually called
gaussmeters.
 Magnetic field sensors are divided into two
categories based on their field strengths and
measurement
 Range: magnetometers measure low fields
and gaussmeters measure high fields.
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7. MAGNETIC FIELD SENSOR
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8. MAGNETIC FIELD FUNDAMENTALS
 An understanding of the nature of magnetic
fields is necessary in order to understand
the
techniques used for measuring magnetic
field
strength. The most familiar source of a
magnetic field is the bar magnet.
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9. Magnets produce magnetic fields. A magnetic field is a vector
quantity with both magnitude and direction properties.
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10.  The field it produces is shown in Figure.
Magnetic field is a vector quantity; that is, it
has both a magnitude and a direction.
The field of a bar magnet or any other
magnetized object, when measured at a
distance much greater than its longest
dimension, is described by Equation
H = 3 ( m × ar ) ar – m / r³
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11. Magnetic fields are also produced by electric
currents
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12. MAGNETOMETER
 Definition
Magnetometer are measurement instruments
used for two general purposes: to measure
the magnetization of a magnetic material like
a ferromagnet, or to measure the strength
and, in some cases, the direction of
the magnetic field at a point in space.
12

13. OBJECTIVES
 Magnetometers are widely used for
measuring the Earth's magnetic field and
in geophysical surveys to detect magnetic
anomalies of various types
 They are also used militarily to detect
submarines
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14. TYPES OF MAGNETOMETER
 There are two basic types of magnetometer
measurement
1. Vector magnetometers
2. scalar magnetometers
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15. 1. VECTOR MAGNETOMETERS
 Vector magnetometers measure the vector
components of a magnetic field
 measure the component of the magnetic field
in a particular direction, relative to the spatial
orientation of the device.
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16. VECTOR MAGNETOMETERS
 Low-Field Vector Magnetometers
 The Induction Coil Magnetometer
 The Fluxgate Magnetomete
 The SQUID Magnetometer
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17. THE INDUCTION COIL MAGNETOMETER
 The induction or search coil, which is one of
the simplest magnetic field sensing devices,
is
based on Faraday’s law.
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18.  This law states that if a loop of wire is
subjected to a changing magnetic flux, f,
through the area enclosed by the loop, then
a
voltage will be induced in the loop that is
proportional to the rate of change of the flux:
e (t )= - dɸ / dt
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19. Induction or search coil sensors consist of a loop of wire (or a
solenoid), which may or may not surround a ferromagnetic core. (a)
Air core loop antenna; (b) solenoid induction coil antenna with
ferromagnetic core
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20. THE FLUXGATE MAGNETOMETER
 The fluxgate magnetometer has been and is
the workhorse of magnetic field strength
instruments both on Earth and in space. It is
rugged, reliable, physically small, and
requires
very little power to operate.
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21. (a) and ring core
(b) fluxgate sensors, the excitation field is at right angles to the
signal winding axis. This configuration minimizes coupling
between the excitation field and the signal winding
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22. THE FLUXGATE
 The heart of the magnetometer is the
fluxgate. It is the transducer that converts a
magnetic field into an electric voltage
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23. 2. SCALAR MAGNETOMETERS
 Total field magnetometers or scalar
magnetometers measure the magnitude of
the vector magnetic field
 measures the total strength of the magnetic
field they are subject to
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24. SCALAR MAGNETOMETERS
The two most widely used scalar
magnetometers are the
1. proton precession
2. optically pumped magnetometer
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25. PROTON PRECESSION
 They have a limited magnetic field magnitude
measurement range: typically 20 mT to 100
mT. And they have limitations with respect to
the orientation of the magnetic field vector
relative to the sensor element
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26. OUTLINE
 Magnetometer data: what are we
measuring?
 Ground magnetic signatures of
 Earth’s magnetic field
 Ring currents
 Auroral currents
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27. EARTH’S MAGNETIC FIELDS
 The Earth's magnetic field is both expansive
and complicated. It is generated by electric
currents that are deep within the Earth and
high above the surface. All of these currents
contribute to the total geomagnetic field
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28. CONTINUE
 In some ways, one can consider the Earth's
magnetic field, measured at a particular
instance and at a particular location, to be
the superposition of symptoms of a myriad of
physical processes occurring everywhere
else in the world.
 Magnetic fields are vectors: they have a
strength (magnitude) and a direction just like
velocity
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29. MAGNETIC FIELD STRENGTH
 The strength of a magnetic field is the
magnetic flux density, B.
 The units of magnetic flux density is the Tesla
or the Gauss
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30.  1 Tesla (T) = 104 Gauss (G)
 The most powerful magnets in the world are
superconducting electromagnets. These
magnets have magnetic fields of around 20
T.
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31. CONTIUE
• Earth’s magnetic field is
 0.000 052T = 52,000 nanotesla (nT) = 0.5 gauss
(G)
• 1 nanotesla = 10-9 T
• Changes in Earth’s magnetic field are
typically 5-100 nT
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32. TESLA
 The applied magnetic field will be one tesla
when one coulumb charge enters in it
perpendicularly with velocity 1 m/s and
experience 1N magnetic force.
 Also Wb/m2 is the unit of magnetic field.
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33. HOW MAGNETOMETERS WORK
 Magnetometer measures the magnetic field it
is applied to. The magnetometer outputs
three magnitudes: X, Y and Z. From these
three values you can construct the magnetic
field vector (magnitude and direction)
B= [X, Y, Z]
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34. COORDINATE SYSTEMS
 Because magnetic fields have a direction, in
order to communicate about magnetic fields,
we need to define a coordinate system.
 Three main coordinate systems are used for
magnetometer data:
– Geographic (XYZ)
– Geomagnetic (XYZ or HDZ - BEWARE!!)
– Compass-type (HDZ)
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35. SOME IMAGES OF EARTH MAGNETIC FIELD
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