Using the output of one charge pump as the constant supply of another, with the same voltage pulse source for both.
The pot's there because every power supply should be tested with a load.
With a single stage, I noted:
It looks like peak voltage is limited by the 2 diodes: 5*2-1.4=8.6.
Applying the same formula, I'd expect 12.2V; 5*3-2.8. It goes up to 12.3V at low/no load, which is close enough that I think my formula still fits.
