Generation of Magnetic Fields
Defined magnetic fields can be generated by permanent magnetic or coil-based structures. There is a great deal of expertise for both processes in the magnetic device construction group. Depending on the application, air coils (e.g. coils in Helmholtz arrangement) or coils with ferromagnetic core are used. All variants can be single or multi-axis and controlled with very precise D/A units as well as highly stable power sources. A zero field or any field configuration can be generated inside the coils. The coil systems can be used to determine and calibrate the gradient and orientation of magnetic field sensitive sensors with high precision.
The coil axes can be driven with the same polarity in homogeneous mode, as well as with opposite polarity in gradient mode. Depending on the application, single-axis or multi-axis AMR or fluxgate magnetometers are used as reference sensors. A specially developed non-magnetic temperature chamber at INNOVENT allows test specimens to be tempered between -55°C and 100°C.
Application examples:
- Compensation of the earth's magnetic field
- Homogeneous and gradient operation mode
- Linearity measurements
- Measurement of the alignment of magnetic sensor elements
- Manipulation of magnetic objects
- Creating in-plane fields inside of wafers
- Yoke assemblies for coupling into ferromagnetic materials
Magnetic Field Shielding
The shielding of electric fields is essential in many applications in order to guarantee the function of the electronics used, and not to interfere with other electronics and systems.
Besides this, the shielding of magnetic fields is becoming more and more important. The spread of magnetic sensors, such as current sensors or displacement and angle sensors, is increasing. There is also an increase of magnetic sources of interference, such as large current-carrying conductors in the field of drive technology.
Our expertise in the area of stray field measurement and simulation of magnetic fields enables us to develop and implement effective, problem adapted shielding concepts. Depending on the application, the shielding can be active through coil systems or passive through a smart combination of materials.
- Static and low frequency magnetic fields
can be actively shielded by coil systems (for example with long coils or Helmholtz coils) and/or with soft magnetic materials, such as ferromagnetic materials with high permeability and low remanence (e.g. NiFe / Permalloy). The magnetic shielding also has an electrical shielding effect, if the material is sufficiently conductive.
- High-frequency magnetic fields
can also be shielded by soft magnetic materials with high permeability. At higher frequencies, the shielding can be done with metal sheets with good electrical conductivity, which do not have to be ferromagnetic. This is because of the eddy currents induced in the shields, which counteract the generating magnetic field. The sheet thickness must be greater than the skin depth to avoid currents on the shielded side.
