I needed clarifications on how the parameters (current, frequency etc) that causes a sparkplug electrode (in an electrohydraulic lithotripter) to generate a shockwave of a particular pressure. Basically what factors controls the output pressure of the wave...?

From what i understood it's the collapsing of a bubble that produces a wave in water. So what factor is responsible so that we obtain the desired output when a spark-gap electrode is used.

Any suggestions, materials or links are most welcome. I require this information for a coursework. Thank you.