Superconducting Magnet Assembly With Voltage Peak Attenuation

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Solution Overview

Problem

Superconducting magnet systems for high-resolution NMR face challenges in maintaining field stability due to ohmic resistance, especially in high-field magnets using high-temperature superconductors, leading to field fluctuations and heat input issues when using conventional current sources or flux pumps.

Innovation Solution

Incorporating a network with at least one inductor and resistor to smooth out voltage fluctuations, acting as a low-pass filter, which temporarily stores and releases energy to maintain a constant voltage across the magnet, effectively damping field fluctuations and reducing heat input.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional current source is used as feed, then current fluctuations are damped, but large amounts of heat are introduced into the cryostat

Engineering Contradiction:

Improvefield stabilityVSAvoidheat input

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the conventional electrical current source with a flux pump that uses electromagnetic induction to generate current. The flux pump uses a superconducting coil system driven by a periodic voltage source, creating current through electromagnetic induction rather than direct electrical connection, thereby reducing heat input into the cryostat while maintaining field stability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If a flux pump is used as feed, then heat input into the cryostat is reduced, but voltage spikes and periodic fluctuations occur

Engineering Contradiction:

Improveheat inputVSAvoidvoltage stability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent introduces an intermediary RC circuit (resistor-capacitor network) between the flux pump and the magnet coil system. This RC circuit acts as a buffer that smooths out voltage spikes and periodic fluctuations from the flux pump, providing stable voltage to the magnet while allowing the flux pump to operate with reduced heat input.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the operational parameters of the flux pump system by introducing an external voltage source with specific frequency and amplitude characteristics. The periodic voltage source is designed to drive the superconducting coil at optimal parameters, and the RC circuit further adjusts the voltage parameters to eliminate spikes and fluctuations.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If high-temperature superconductors are used, then magnet performance is improved, but ohmic resistance increases causing voltage fluctuations

Engineering Contradiction:

Improvemagnet field strengthVSAvoidfield stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the harmful ohmic resistance effect into a beneficial one by using the flux pump system. Instead of trying to eliminate resistance, the periodically driven superconducting coil in the flux pump generates current that compensates for resistive losses. The RC circuit further stabilizes the voltage, transforming the resistance problem into an opportunity for active current generation that maintains field stability despite high-temperature superconductor limitations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This solution ensures stable high-resolution NMR measurements by smoothing voltage fluctuations, allowing for the use of flux pumps in sensitive applications without disrupting measurements, and enabling the development of stronger and more compact magnet systems.

Implementation Method 1

A magnet arrangement with a superconducting magnet coil system, which has a working volume and in the operating state an ohmic resistance greater than or equal to zero, and with at least one current path

Methodology Applied

Scientific EffectLow-pass filtering: Filter (electronic)

Implementation Method 2

Magnet arrangements with a superconducting magnet coil system are required in particular for magnetic resonance measurements (NMR)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

Superconducting magnet systems for high-resolution NMR are normally operated in 'persistent' mode, ie the circuit is short-circuited so that no active excitation is required once the magnet is charged

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentEP1720179A3Magnet assembly with means for the attenuation of voltage peaks of a power supply and method for operating the magnet assembly

Publication Date: 2008.07.30 BRUKER BIOSPIN AG

AI summary

The connection points (AP1,AP2) of a current path (P) in a solenoid coil system (M) are connected to the connection points (AD1,AD1) of an electrical network (D1) while a supply (PS') is connected to the connection points (AD3,AD4) of the electrical network. The electrical network includes at least one resistor (R1) and an inductor (L1) that interconnects the connection points (AD1,AD2) to the connection points (AD3,AD4). An independent claim is also included for a magnet arrangement operation method.