good luck with the experiments, in my setup a two coating system is needed for the inner cylinder one n-type one p-type to make a large diode and work like a polyfuse too... the source doesnt see the outer cylinder but the water as positive while the outer cylinder sees the inner cylinder as negative.. energy is stored in the capacitor device and because electrons from inner cylinder have done chemical work (electrolysis) the energy stored in the capacitor is over farady , ofcourse you need ns pulses and high voltage otherwise displacement current kicks in I suppose...and some way to discharge the capacitors to reuse this energy without thermal loss prob LC circuit..