How to enlarge leakage inductance for experiment

Leakage Inductance Issue
It is determined by structure of transformers, not easy for change. a possible way is adding inductance in series with the primary (high voltage side), so as to increase the voltage that applies on the transformers.
The principle behind this the series inductance be in series with equivalent capacitance, but it requires that the insulated voltage level of series inductance should be high enough.

Also increase the gap between winding and core, or between different windings can also enlarge leakage inductance.

Leakage inductance is supposed to be controlled in low value with consideration of applications. And in practice it is not easy to measure and assume, but most of the study and application consider that to be a constant value (due to what kind of use)

IEEETM Notes