Magnetic Sensor Field Nulling With Programmable Remanent Magnets
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Solution Overview
Problem
Magnetic sensors, such as SQUIDs and Rydberg cells, are saturated by ambient magnetic fields like the Earth's magnetic field, leading to loss of sensitivity and linearity, and active field nulling techniques introduce thermal noise.
Innovation Solution
Position programmable permanent magnets near the sensor to generate counteracting fields using pulsed currents, adjusting remanent magnetization to nullify the terrestrial field without introducing additional noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active feedback systems are used to cancel ambient magnetic fields, then the sensor can operate in zero net field condition, but thermal noise is introduced through Johnson noise in the electronic circuits
Solution Approach 1:
The patent applies periodic pulsed currents to the magnetic structures instead of continuous feedback currents. The controller periodically adjusts the remanent magnetization of the magnetic structures by applying pulsed currents only when needed to maintain the sensor in its linear range, rather than using continuous active feedback. This periodic action reduces thermal noise while maintaining measurement precision.
Solution Approach 2:
The magnetic structures with remanent magnetization serve themselves to cancel ambient fields without requiring continuous external power or active feedback circuits. Once magnetized, the magnetic structures passively generate the necessary counteracting fields, eliminating the need for continuously powered feedback electronics that generate Johnson noise.
2Object-affected harmful factors
If continuous feedback currents are applied to nulling coils, then ambient magnetic fields are canceled, but power consumption increases and thermal noise is generated
Solution Approach 1:
Instead of applying continuous feedback currents, the system uses periodic pulsed currents to adjust the remanent magnetization of magnetic structures. The controller monitors the sensor output and applies pulsed currents only when the sensor approaches the boundaries of its linear range, significantly reducing power consumption compared to continuous operation.
Solution Approach 2:
The magnetic structures, once magnetized with remanent magnetization, provide continuous field cancellation without requiring continuous power input. The stored magnetic energy in the magnetized structures sustains the nulling effect passively, eliminating the need for continuously powered coils and reducing overall system power consumption.
3Measurement precision
If quantum-effect based magnetometers are used, then high sensitivity and low noise characteristics are achieved, but saturation occurs at field strengths many orders of magnitude below terrestrial magnetic field
Solution Approach 1:
The patent introduces magnetic structures as intermediary elements between the ambient magnetic field and the sensitive quantum magnetometer. These magnetic structures, with controllable remanent magnetization, act as a mediator that generates counteracting fields to cancel ambient fields, allowing the sensor to operate in its sensitive linear range even in the presence of strong terrestrial magnetic fields.
Solution Approach 2:
The system dynamically changes the magnetic field parameters by adjusting the remanent magnetization of the magnetic structures. The controller monitors the ambient field strength and adjusts the magnetization state of the magnetic structures to maintain the net field at the sensor within the linear range, effectively expanding the usable dynamic range of the quantum magnetometer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces power consumption and noise floor by precisely canceling ambient fields, maintaining sensor sensitivity and linearity without thermal noise.
Implementation Method 1
a magnetic sensor configured to detect an ambient magnetic field
Implementation Method 2
generate a pulsed current based on the generated error signal, the pulsed current applied to an electromagnetic coil surrounding the one or more magnetic structures
Implementation Method 3
adjust a remanent magnetization of the one or more magnetic structures based on the generated error signal
Data Source
AI summary
A system for nulling ambient magnetic fields is disclosed. The system includes a magnetic sensor for detecting an ambient magnetic field, one or more magnetic structures positioned proximate to the magnetic sensor, and a controller. The controller includes one or more processors and is configured to receive a signal from the magnetic sensor, the signal associated with a strength value of the detected magnetic field; compare the strength value to a linear range associated with the magnetic sensor; generate an error signal, via an integrating amplifier, in response to the signal approaching one or more extreme values within the linear range; generate a pulsed current based on the error signal and apply the pulsed current to an electromagnetic coil surrounding the one or more magnetic structures; and adjust a remanent magnetization of the one or more magnetic structures based on the error signal.