Vector Potential and Magnetic Field of Axially Symmetric Currents
  A solution is proposed for finding the vector potential and magnetic field of any distribution of currents with axial symmetry. In this approach, the magnetic field and the vector potential are looked for not by solving a differential equation but rather through straightforward calculation of integrals of one scalar function. The solution is expressed in terms of the associated Legendre polynomials P_{lm} with the index m of the Legendre polynomials assuming one value only, m = 1. The solution has the form of a series, with the coefficients of the polynomials being combinations of multipole moments.   Key words: electrodynamics, vector potential, spherical harmonics, Legendre polynomials, magnetic field. 
Andrey Vasilyev
physics.class-ph