Industrial Gaussmeter IGM11 Operating Instructions
Chapter 3 Function of the Gaussmeter
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3.1.2.2
Reasons for the Field Dependence of the Sensitivity
There are several influences for the flux density dependence of the sensitivity:
The mobility of the charge carriers depends on the flux density. This influence
generally leads to a negative
α
Hall
and is irrelevant for the used Hall sensors. More
important is the geometry of the used sensors. The lamellar structure generates a
geometry-based field dependence of the sensitivity. The non-homogeneous
distribution of the current density in such a structure causes this effect. Already in
field-free cases, this current distribution on the Hall element is relatively complex. This
entails a lowering of S
0
and influences the field dependence of the sensitivity. A
complex real-time correction of the gaussmeter IGM11 compensates for the inherent
non-linearities of the used Hall probes and thus ensures a stable zero point.
3.1.2.3
Field Dependence of the Cross-Current Resistance
The current distribution is the cause of the Hall probe resistance. Current components
which – alike the Hall voltage – run vertically to the direction of the current feed,
cause a diverted Hall effect. This becomes noticeable as a flux density modulated
resistance.
For measuring fast magnetic impulses, the device must have sufficiently high
dynamics in order to equalize this effect. The gaussmeter IGM11 is optimized for this
operating mode.
3.1.2.4
Temperature Dependence of the Sensitivity
Due to the large band gap of the used Hall sensors the temperature dependence of
the probe sensitivity is low. It is approx. −0.06 %/ºC.
3.1.2.5
Temperature Dependence of the Cross-Current Resistance
The temperature dependence of the cross-current resistance is appox. 0.3 %/ºC and
is automatically equalized by the device.
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