Project Description

custom permanent dipole magnet

What Is Permanent Magnetic Dipole?

The permanent magnetic dipole is a high field of magnet assembly, a magnetic lab device for physical research projects. It consists of a pair of permanent magnets across a gap. The magnets are usually mounted on a steel frame (also called a yoke) for magnetic efficiency, magnetic shielding and/or mechanical strength.

In particle accelerators, the dipole magnet is usually made from electromagnet. For example, all the magnets on the LHC are electromagnets. But permanent magnets have many advantages over electromagnets in terms of electric power consumption, stability and reliability. So, the dipole based on permanent magnets can be an alternative for small bore accelerators.

The specific advantages and disadvantages of dipole magnets using permanent magnet are as follows:

Advantages of Permanent Magnetic Dipole

  • No Power Required – permanent magnet based dipole magnets require no current to provide a constant field. No large power supplies are required, and no current-carrying cables, and there is a less risk of power supply failure.
  • Lower Cost – Permanent magnet dipole assemblies are physically more compact, their cost will be lower than the cost of making electromagnets. At the same time, no electronics or moving parts, there is no maintenance other than keeping them clean and protected from damage; no heat dissipation and therefore no need for water cooling (which also eliminates a potential source of vibration). As a result, running costs can be lower than electromagnets in the long term, and of course, CO₂ emissions during operation are significantly reduced.
  • Less Exposure to Magnetic Fields –  The magnetic field in a permanent magnet dipole assembly is confined by or contained within the gap, so exposure to “stray magnetic fields” is far less likely than exposure to a strong electromagnetic field.

Disadvantages of Permanent Dipole Magnets

  • Temperature Stability – Remanent field Br changes as a function of temperature. The temperature coefficient of samarium cobalt is approximately -3×10-4/°C and NdFeB is about -1×10-3/°C, so this affects NdFeB magnet more than samarium cobalt.
  • Radiation – Impact of a high-energy particle in a permanent magnet material can cause a release of energy, leading to nucleation of inverse domains in a permanent magnet.
  • Tolerances – A batch of permanent magnet blocks will have tolerances on dimensions and magnetisation strength and direction.
  • Magnetic Field Limitations & Adjustability – Based on the magnetic materials, gap size and physics, there is a limit to the magnetic field that a permanent magnet dipole can generate. While electromagnets can easily generate magnetic fields of 3-5 Tesla in a large gap, permanent magnet dipole assemblies is more difficult. However, scientists are constantly working on new magnet materials, pole arrangement and assembly techniques to create permanent magnetic dipoles with higher magnetic fields.

Applications of Permanent Magnet Dipole

Halbach dipole is the most efficient permanent magnet structure for generating magnetic field higher than the remanence of the magnetic material. So dipole magnets and magnetic yokes are special designed for critical applications where highly-concentrated magnetic strength or high-uniform magnetic fields are required.

The dipole magnet can be used to identify the long-lived atoms, to bend particle beams, to create a homogeneous magnetic field. It is a device commonly used in physics laboratories to study particle accelerators.

Other uses are as follows:

  • mass spectrometer
  • probe calibration
  • nano particle separation
  • portable nuclear magnetic resonance (MR & MRI) equipment
  • magnetic annealing (thin films, alloy ribbon and amorphous cores)

Magnet Materials for PM-based Dipole

All current permanent magnets can be used to make dipole magnets. But different materials have different magnetic properties. Therefore, we need to choose magnetic materials according to the actual application requirements.

Neodymium Iron Boron has the highest magnetic energy, so it is chosen when a large magnetic field is required. Sm2Co17 magnets have the highest magnetic energy equivalent to N35 NdFeB magnets, but they are more resistant to high temperatures compared to NdFeB  (>300°C).

Hard ferrite is used if cost is more important than large magnetic fields. Alnico is generally used if dipole is to be used in high temperature environment (>450°C).

Manufacturing of Dipole Magnet Assemblies

Dipole magnets, driven by permanent magnet (NdFeB or SmCo) blocks rather than a coil, resulting in low environmental impact due to zero energy consumption. While the potential advantages are great, the practicalities of manufacture and use pose some significant challenges.

Permanent magnets have strong magnetic force, which causes strong attraction and repelling forces occur when they are brought close to iron objects or themselves. Magnets are difficult to handle and position.

It is therefore essential in the production of dipole magnets that the magnets are assembled safely without damaging the block or the assembler.

permanent dipole magnets for DIRAC

permanent dipole magnets by CERN

Design of Earth Dipole Magnet

The design of a permanent magnet dipole assembly requires consideration of gap, magnetic field, dimensions, and operating conditions. Also, as these factors are interconnected, they need to be considered together and not just separately.

Inquiry of Custom High Field Permanent-magnet Dipole

When you send us an inquiry for dipole magnet, please make sure to include the following information:

  • What is the minimum magnetic field strength required?
  • How large a volume?
  • How large can the dipole be, does it have to fit within other devices?
  • Will the dipole be exposed to elevated or cryogenic temperatures?
  • Will the dipole be exposed to vacuum or corrosive gases/fluids?
  • Do you need the polarity marked?

Manufacturer of Various High Field Permanent Dipole Magnets

Magnet researchers have been on a quest to generate a magnetic field strength as high as possible. And the dipole magnet is a magnetic equipment tool designed and constructed to this aim. Different Physics research projects require different magnetic fields, so scientists often need to design new dipole magnets.

They usually achieve much higher magnetic fields through a special Halbach type magnetic circuit. The highest magnetic field is constantly setting new records from 1T, 2T, 4T, 6T to 10T or higher.

If you are looking for dipole magnet unit or single magnet for high field assembly for research project, kindly contact us by below form.

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