Centre for
SPACE PHYSICS
Centre for Space Physics

Detecting ULF waves

 

There are two common instruments used to detect the signatures of ULF waves. These are induction and fluxgate magnetometers.

Induction magnetometer

A time varying magnetic flux through a coil of wire generates a voltage. We have designed induction magnetometer systems that are used in Antarctica, South Africa, China, and Australia.
The sensor has 190,000 turns of cooper wire wound onto a PVC bobbin, which is then threaded with mu-metal strips. The resulting inductance is about 10,000 Henries. A specially designed, chopper type, pre-amp boosts the signal which is then fed to an A/D board, designed by Peter McNabb.

Fluxgate magnetometer

These are very good for the low end of the ULF wave spectrum, measuring the ambient (steady) field up to variations of about 1 Hz. Hysteresis of the ring core material produces harmonics that depend on the applied magnetic field (Earth's field). Our systems were designed and built by Narod Geophysics, Vancouver, Canada.