Magnetic Fields: Harmonic Perturbation 1

Dear all,

I'm simulating a multi-turn coil (N=100) with Icoil=1Ampere. When I put Harmonic Perturbation on, the coil inductance changes. Why? what is happening in harmonic perturbation?
In Frequency domain: i have frequencys of 10.000, 1000 and 100.

I thought: the current in Multi-Turn Coil is DC, and the current in Harmonic Perturbation is AC.
but when i put harmonic perturbation off, the 3 frequencys in frequency domain still work. so.... that's neither correct is it?

So.. what is Harmonic Perturbation then?

I hope you can help me?

Regards,

Job.