Cryogen Cooling Coil Isolation for Low Eddy Current MRI Magnets

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Solution Overview

Problem

Superconducting MRI magnets face increased heat loads due to eddy currents generated by fringe fields, which degrade imaging quality and require reducing AC field strength, compromising system performance.

Innovation Solution

A low eddy current cryogen circuit with electrically conducting cooling coils incorporating electrical isolators to inhibit induced eddy currents, maintaining AC field strength while reducing heat loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If electrical isolators are incorporated in cooling coils to inhibit eddy currents, then heat load is reduced, but device complexity increases

Engineering Contradiction:

Improveheat load from eddy currentsVSAvoidcomplexity of cooling coil structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The cooling coil is segmented into multiple sections with electrical isolators positioned at specific locations. This segmentation interrupts the continuous electrical path that would otherwise allow large eddy current loops to form, thereby reducing the heat load while maintaining cooling effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Electrical isolators are introduced as intermediary components within the cooling coil structure. These isolators act as mediators that block electrical current flow between different sections of the coil, preventing eddy current formation without significantly impacting the thermal conduction path.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If AC field strength is reduced to minimize eddy currents, then heat load decreases, but imaging quality deteriorates

Engineering Contradiction:

Improveheat load from eddy currentsVSAvoidimaging quality

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

By segmenting the cooling coil with electrical isolators, the system can maintain full AC field strength for high-quality imaging while the segmented structure naturally limits eddy current loops to smaller sections, reducing overall heat load without compromising imaging performance.

Inventive Principle:

Principle #1Segmentation

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

Effectively reduces heat generated from eddy currents without compromising AC field strength, enhancing imaging quality and system performance by using a low eddy current cryogen circuit with electrical isolators in the cooling coils.

Implementation Method 1

eddy currents are produced. These eddy currents generate joule heating which increases the heat load

Methodology Applied

Scientific EffectEddy Currents: Eddy Currents

Implementation Method 2

inductive coupling of the first cooling coil with eddy current inducing field sources

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 3

passing a cryogen through the first cooling coil

Methodology Applied

Scientific EffectThermal Conduction: Conduction (thermal)

Implementation Method 4

superconducting magnets which utilize superconducting magnets

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Implementation Method 5

These eddy currents generate joule heating which increases the heat load

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Data Source

PatentUS7464558B2Low eddy current cryogen circuit for superconducting magnets

Publication Date: 2008.12.16 GE PRECISION HEALTHCARE LLC

AI summary

A low eddy current cryogen circuit for superconducting magnets including at least a first cooling coil made of an electrically conducting material and having at least one electrical isolator incorporated in the first cooling coil. The electrical isolator is located to inhibit induced eddy current loops due to inductive coupling of the first cooling coil with eddy current inducing field sources.