By: Michael Brand, President, SM Magnetics

Linear Halbach Arrays can be the perfect solution for many applications. But is it right for yours?  There is much about a Linear Halbach that requires technical consideration, but let’s start with some of the basics. 

Benefits of Using a Linear Halbach

  1. The main application we see using linear Halbach arrays is for holding or pull force, however these can be used in other applications, ranging from medical, research, and sensors.
  1. Just like a circular Halbach, a Linear Halbach is self-shunting. This means that the magnetic field on one side of the Halbach array is very strong while the opposite side is almost zero.  The image below shows the simulated magnetic field profile of a common Linear Halbach array.  From this simulation you will notice the orientation of the magnets from the arrows, and you can see that the magnetic field on the bottom is very strong, while the magnetic field on the top is almost non-existent. 

      

  1. A Linear Halbach can be designed to “throw the field” further or keep it closer to the surface. Even though it is possible to design these arrays to increase the field further from the surface, there is a point of diminishing returns and a linear Halbach is not the correct choice.  Since the purpose of the Linear Halbach is to provide more focused magnetic field on the surface, it has a limit to its usefulness if the air gap between the surface and its target is too large.
  1. The array can be “tuned” to a specific air gap. As long as the air gap is appropriate for a Linear Halbach, the array can be tuned so the application is utilizing the correct amount of magnetic field within the required air gap.        

Other Considerations of Using a Linear Halbach

  1. The magnetic materials used to make a Linear Halbach should have a higher coercivity.Magnets have the potential to demagnetize if exposed to a high magnetic field.  Since Halbach arrays require magnets assembled in ways that push an opposing fields toward each other, Linear Halbach arrays should be made with a magnet that can withstand this demagnetizing force. 
  1. Assembly of a Linear Halbach is more difficult than an assembly with multiple poles.This is because the magnets will want to push apart during assembly.  For this reason, there is usually a one-time jig or fixturing charge.
  1. Linear Halbachs are generally more expensive. This is mainly due to the need for a higher, more expensive coercivity material, and the added labor time for assembly and manufacturing.   

It is always best to speak with a magnetics consultant to determine if a Linear Halbach is correct for your application, and the array needed. 

About SM Magnetics:  SM Magnetics is a privately-owned company which provides assistance with magnets, magnetic circuit design, engineering support, and production.  For more information, log on to our website, www.smmagnetics.com, or contact us at 205-621-8841.


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