Cyclic boundary conditions

Goodmorning everybody,
I’m using freefem for the solution of magnetostatic problems. My problem is the simulation of a toroidal solenoid that of course it is discrete over the toroidal direction since it is composed, over the 360°, of 18 spires. I was able to evaluate without problems the self-field of each spire but now I actually want to simulate the entire solenoid. For computational cost reasons I do not want to model all the 18 spires, but I suppose that it should be possible to model only 1/18 of the total domain and,given that the remainig 17/18 of the domain behaves in the same way, imposing cyclic boundary conditions obtain the results representative of the total solenoid.
Since I am pretty new of the use of this software and I was not able to find out anything similar in the documentation I’m asking if some of you have already encoutered such a problem and if some of you can suggest me the way in which this kind of condition can be imposed!

I’m already thanking a lot anyone will help me in the solution of this problem!

Best regards,