At the high frequency at which it operates, the secondary winding of the Tesla coil does not behave as a lumped element inductor, as transformer windings at lower frequencies do, but must be viewed using the distributed element model.
At the high frequency at which it operates, the secondary winding of the Tesla coil is long enough that it is a significant fraction of a wavelength. Therefore it does not behave as a lumped element inductor, as transformer windings at lower frequencies do, but must be viewed using the distributed element model.