A Quick Introduction to Halbach Array Rings

The Halbach array is a magnet structure with a special shape. Its design idea is to combine multiple magnets of the same shape but different magnetization directions into a circular ring magnet to enhance the uniformity and stability of the working surface or center magnetic field.

Permanent magnet motors using the Halbach array structure have an air gap magnetic field that is closer to a sinusoidal distribution than traditional permanent magnet motors. When the amount of permanent magnet material is the same, the air gap magnetic density of the Halbach permanent magnet motor is larger and the iron loss is smaller.
In addition, the Halbach annular array is also widely used in permanent magnet bearings, magnetic refrigeration equipment, magnetic resonance equipment and other equipment.

Advantages

1. Strong magnetic field: The Halbach array rings adopts the design of ring magnet, so that the magnetic field can be concentrated and focused in the whole ring structure. Compared with ordinary magnets, ring magnets can generate higher intensity magnetic fields.
2. Space saving: The ring structure allows the magnetic field to loop in a closed loop path, thereby reducing the space occupied by the magnet. This makes the ring magnet more convenient to install and use in some occasions.
3. Uniform distribution of magnetic field: Due to the special design structure of the annular Halbach magnet, the magnetic field is distributed more evenly in the annular path. This means that when using an annular magnet, the intensity change of the magnetic field is relatively small, which is conducive to improving the stability of the magnetic field.
4. Multi-polar magnetic field: The design of the Halbach array rings can generate multi-polar magnetic fields, allowing more complex magnetic field configurations to be achieved in specific application scenarios. This provides greater flexibility and operability for experiments and applications with special needs.
5. Energy saving and environmental protection: The design materials of the Halbach array rings usually use materials with high energy conversion efficiency. At the same time, the waste of energy can be reduced through reasonable design and optimization of the magnetic circuit structure, thus achieving the purpose of energy saving and environmental protection.

Under traditional technology, various types of Halbach arrays are mostly assembled after pre-magnetization when used. However, due to the variable force direction between the permanent magnets in the Halbach permanent magnet array and the high assembly precision, the permanent magnets after pre-magnetization often require special molds when assembled.
The overall magnetization technology adopts the method of assembly first and then magnetization. The permanent magnets are non-magnetic during assembly, and the Halbach array can be assembled without custom molds. At the same time, the overall magnetization technology can also improve the magnetization efficiency, reduce energy costs and assembly risks, and has broad application prospects. However, due to the high technical difficulty, it is still in the exploratory stage, and the mainstream market is still produced by pre-magnetization and then assembly.

Application

1. Medical imaging: Halbach array rings are also commonly used in medical imaging equipment, such as magnetic resonance imaging (MRI) equipment. This type of magnet can generate a stable magnetic field to locate and excite the nuclei in the object being tested, thereby obtaining high-resolution imaging information.
2. Particle accelerators: Halbach array rings can also be used in particle accelerators to guide and control the movement path of high-energy particles. This magnet can generate a strong magnetic field to change the trajectory and speed of particles, thereby achieving particle acceleration and focusing.
3. Ring motor: Halbach array rings can also be used in motor design to generate driving torque. This magnet can generate different magnetic fields by changing the direction and magnitude of the current, thereby driving the motor to rotate.
4. Laboratory research: Halbach array rings are often used in physics laboratories to generate stable and uniform magnetic fields for research in magnetism, material science, etc.

Key Parameter

1. Magnetic field requirements: According to actual needs, determine the magnetic field strength required by the magnet to meet the application requirements. This will determine the size, material and design of the selected magnet.
2. Size limitation: Consider the limitation of magnet installation space and determine the appropriate outer diameter, inner diameter and height to ensure the appropriate selection.
3. Temperature requirements: Determine the maximum temperature limit when the magnet is running to select appropriate materials and cooling measures.
4. Corrosion resistance: Consider the corrosion resistance of the magnet in special environments and select suitable materials and coatings to protect the magnet.
5. Stability requirements: For applications that require maintaining a stable magnetic field, select magnets with higher magnetic field stability and lower magnetic field drift rate.
6. Magnet weight: According to the requirements of the application scenario, consider the weight limit of the magnet and outer ring to facilitate installation and transportation.
7. Cost-effectiveness: Consider the performance and price of the magnet comprehensively, and select magnets with higher cost-effectiveness to best meet application requirements.