OPTIMIZATION OF SMES SOLENOIDS WITH REGARD TO THEIR STRAY FIELDS

Solenoidal SMES (Superconducting Magnetic Energy Storage) usually suff er form their remarkable stray field. A certain arrangement was devise d that should reduce the extension of the far ranging stray field. Hen ce, a second solenoid was placed outside the SMES device with a curren t flowing in the opposite direction compared to the inner coil. Config urations with both coils in a single plane were regarded only. As an i mportant factor the minimum energy to be stored was given. In a first step calculations methods have been found that reveal data for the min imum geometrical dimensions of the SMES device in an analytical way. I t was shown that the stray field, compared to a single coil arrangemen t could be reduced remarkably. Evolution strategies and a conjugate gr adient method were used to improve the quality of the above solution.