The relationship of levitation force between single and multiple YBCO bulk superconductors

The levitation forces have been measured for many individual and multiple single-domain YBCO bulk superconductors. It is found that the levitation force of multiple YBCO bulk is closely related with levitation force of each individual single-domain YBCO bulk (used for composing the multiple bulks). The resultant force of the multiple YBCO bulks is slightly less than the summation levitation force of each individual single-domain YBCO bulks, while each individual YBCO bulk is fixed in position the same as that in the multiple YBCO bulk. The difference is about 5%, so that we can predict the resultant levitation force of multiple YBCO bulks with various shape and complex configuration more easily. This is very important and useful for simplifying the experimental tests on superconducting devices during designing and constructions for practical applications.