Halbach arrays are an arrangement of magnets that boosts the magnetic field on one side and reduces it on the other.
“Continue reading” for interesting applications including supermagnets and fridge magnets.
The magnets don’t want to sit in this array and have to be forced and glued. Hence the wood supports and a wooden rod to push them together.
Halbach array above with magnetic viewing film showing a large field skewed to the top of the array. Yes I did get confused with the poles. The “S” and “N” labels are correct.
In contrast above, a simple north to south magnet arrangement (that magnets will tend to fall into) has little external field.
This shows the maximum field strength of ? 600 mT on one side and 200 mT on the other. The magnet otherwise only reaches 400 mT. Hence it will stick well to iron on one side but not the other.
Halbach arrays are used in fridge magnets. These only need a strong field on one side so a Halbach array is ideal. It is configured as a sequence of linear rows of array.
The arrangement in rows and strong field on the “sticky” side only are due to long Halbach arrays in repeated rows.
The field of the fridge magnet is shown with viewing film and the associated alternating poles are shown measuring in the +/- 18 mT range.
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External links
Halbach arrays plotted field
http://www.gaussboys.com/store/index.php/magnet-information.html
Photo Date: June 29, 2013