Electrostatic Questions


I have a couple of questions regarding electrostatics.

In the metal pail capacitor experiment where the cap is charged and the 
pails are removed and grounded and then later replaced, it is obvious 
that the charge resides on the dielectric rather than the metal plates.

Question 1: If a gas (air) or liquid dielectric cap is charged and the 
liquid is drained or the air is blown away from the plates what happens 
to the charge on the cap?

I am very interested in DC properties of TCs.  I have devised various 
schemes to add DC bias to the coil so that the TC discharge will also 
exhibit a DC bias  - sort of pulsating DC from the toroid.  
Incredibible DC voltage and current may be developed with only a small 
to moderate TC.  

One way to introduce this DC bias is with a main capacitor that 
selectively charges during the AC waveform, ie., charges easier 
positively or negatively or vise versa.  Note this is not an 
electrolytic or any other polarized cap.  Since most caps are 
essentially two metalic plates on either side of a dielectric, 
selective charging would ordinarily be unusual.

Question 2:  Has anyone made a cap by placing the metal plates on an 
electret dielectric?  Seems to reason that an "electret cap" would 
selectively charge/discharge.  The big question is can ordinary 
polymers such as polyethelene be made (converted) into an electret?
Richard H. or Kim G?