Parametric pumping for tesla coils?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jolyon Vater Cox by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

Dear List,
If I may be so bold, I have been thinking that instead of using switching 
devices to vary currents and voltages as we presently do, how about 
changing say, the capacitance instead -charging at low voltage and 
discharging at high
since charge ,Q,  on an isolated capacitor doesn't change with a change in 
capacitance but stored energy and voltage do vary with changes in the 
capacitance.

Reading from previous postings on the List I understand that it is possible 
to get more voltage out of the secondary of a transformer if the frequency 
of the AC is increased -and vice versa-
the trouble is, the primary voltage must be increased or decreased in the 
same proportion so there is normally no net advantage in changing the 
frequency.
However, if the capacitance of a capacitor, C, resonating in a tuned 
circuit with an inductor ,L, at a frequency ,f1, is changed the oscillation 
changes to a new frequency, f2, and with it the energy in the capacitor and 
the voltage across it.

Now, when a charged capacitor is connected to an inductor energy is 
ordinarily lost in the "damped" oscillation -but if the capacitance (or 
inductance) can  be made to change quickly enough it is possible to 
overcome the losses resulting in a comtinuously-oscillating system. With 
this in mind would it not be entirely possible -at least in theory- to use 
these "parametric" methods in the pumping of Tesla coils?

Could parametric TCs, Q-switching TCs etc, be just be round the corner?