Voltage Quadrupler - Capacitor and Charging Sequence question
It may be called a quadrupler in textbooks,  but it only 2x the peak to peak input voltage to a DC output voltage (minus the diode drops). the reason is the input is an AC signal so the each stage must clamp the negative waveform then the next diode can rectify it followed by the 3rd as a clamp then the 4tbh diode another rectifier.

There are four C-CR pairs (cap + current rectifiers.)


The series Cap shunt diode is called a "signal clamp" as the diode only conducts briefly, partially charges the cap like a momentary switch.
The series diode shunt cap is called a peak and hold detector or "rectifier and filter" or "envelope detector""


If we were to number the diodes from your image from left to right as D1,D2,D3,D4 we get voltage test points as follows;


D1: -ve clamp
D2: +ve Peak &amp; Hold  = Vin_pp minus 2 diode drops
D3: -ve clamp
D4: +ve Peak &amp; Hold = Vin pp minus 4 diode drops


Falstad Sim



High V Quadrupler

Hi V Quadrupler that works ( with plastic caps)


Just remember it takes 2 didoes and 2 caps to make ONE DOUBLER and all the diodes are cascaded in reverse bias like a ladder 


shunt, series, shunt, series ..etc