Why do we need two toroidal cores?

[onemilimeter]

I read somewhere that two or more cores are stacked together to design an inductor or transformer. What is the reason to stack two or more cores?

[Time]

Thats not common.  Might have just been application specific.  Ideally you would want one solid core with no breaks or air gaps for the best Q.

[tecman]

Stacking cores and winding through both increases inductance and power.  Disadvantage is greater losses from leakage inductance, which is the benefit of toroids.

This is usually done as a quick fix.

paul

[onemilimeter]

Stacking cores and winding through both increases inductance and power.  Disadvantage is greater losses from leakage inductance, which is the benefit of toroids.

This is usually done as a quick fix.

One of the parameters given in a toroidal datasheet is AL. When two toroidal cores are stacked together, do you think the effective AL of stacked cores is equivalent to double of the individual core's AL? Thanks.