F.Y.I.Good observation - using high voltage pulses to "fill" a capacitor (in the form of a helical coil)
with "electrons." Recall around 1775 Alessandro Volta named the device "Electtroforo Perpetuo."
Charge it once and it provides a "perpetual" charge. The idea was already developed from
experiments by Wilcke in Sweden around 1762.
The next challenge is to "extract" the excess electrons from this "capacitor-coil" without
rendering it's sequential effect inefficient while still providing an output in the form of
"conventional electricity." Hint; conventional current (electron) flow removal from the device
will result in back electromotive force (B-EMF) if conventional methods are used.
The coil is made as "non-inductive" as possible for good reason but must remain in "coil" form to
facilitate electron extraction and conversion to conventional "hot" electrical form (electrons
passing "through" a wire) in order to complete the system.
Therefore, other techniques must be employed; for example, bi-filar winding or other asymmetric
means. The source of excess electrons is isolated, to a great extent, by nature of electrophoretics;
but that's only half the requirement. The extraction-conversion process is worthy of equal,
or even more, consideration; as is cost and safety.
The
(a) "output" can not disturb the "input," the scheme
(b) has to be extremely efficient,
and should be
(c) very stable; even when considering environmental effects (changes in humidity
and temperature, for example, as well as variations in output loading - current draw).
It's also worth noting that Tesla used high voltage to charge a metal plate, at some distance, and
then extract electrons (current) from that plate through a ground connection. Coating the plate
with dielectric may have helped retard the loss of acquired electrons into the atmosphere.
Anyway, just some humble, simplified thoughts! I'm sure there must be more to it...
FIN