QMAGT – Full-Tensor Magnetic Gradiometry

QMAGT System

The QMAGT system is a helicopter-borne magnetic survey system that measures the magnetic field in a robust and detailed manner. The SQUID (superconducting quantum interference device) sensor measures the complete gradient tensor (second-order) of the earth’s magnetic field (otherwise known as full tensor magnetic gradiometry – FTMG). This FTMG measurement provides directional information about the magnetic field which is not available from total field sensors, which have been the industry standard for many years.

The SQUID sensors are developed by Supracon AG of Jena, Germany. Operating within a liquid helium bath, the sensors measure the magnetic field with unrivaled sensitivity. The sensor system is the result of over 20 years of development and testing and has flown many successful exploration campaigns. The QMAGT system is the full commercialization of this established system.

The QMAGT system is deployed in a custom-built airfoil beneath a helicopter. This ‘bird’ effectively reduces motion noise, allowing for the recovery of high-quality data. As a lightweight system, QMAGT can be deployed in most operating environments.

QMAGT Advantages

  • Plug and play helicopter operation for acquisition in most environments.
  • Direct determination of anomaly geometry, irrespective of whether the source is remanent or induced.
  • Better information on magnetization directions. The magnetic moment of compact sources can be directly determined.
  • Gradient measurements, particularly full tensor measurements, determine on which side of a survey line a source lies.
  • Effective survey results in low latitude environments
  • Redundant tensor components (4 of the 9 measured tensors are redundant) give inherent error correction and noise estimates.
  • Desirable mathematical properties, allowing magnetization mapping, rigorous continuation, reduction to the pole, depth slicing, invariants, etc.

QMAGT Specifications

  • SQUID sensor: 6-channel first-order planar gradiometers
  • Intrinsic gradient noise: <100 fT / (m√Hz)
  • Magnetometer: 4-channels of magnetometers
  • Intrinsic noise: 2 pT / √Hz
  • SQUID electronic bandwidth: > 3 MHz
  • Sampling Rate: 10,000 samples per second
  • Operating temperature range: -10°C to +40°C
  • Cryostat operation: 2.5 days per refill
  • Data acquisition: 20 channels of 24 bit ADCs
  • IMU system: 3 fibre optic gyros, 3 accelerometer sensors
  • Radar altimeter: max of 3 % or 0.5 m
  • Laser altimeter: +/- 1 to 2 cm typical
  • Total bird weight: 267 kg
  • Tow rope: DyneemaTM – 32 m +