Faraday Cage and a high voltage discharge arc

[jaydnul]

In the following video:

I understand how the Faraday Cage works, but what has me confused is the arching. If charge is building up on the sphere and then arching over to the cage, where then is that charge sunk to? You would think it would stop arching when there was sufficient charge on the isolated cage, no?

 

[rootone]

Probably the charge leaks away to ground through the air is my guess. (Unless the cage is intentionally grounded.)
Air is not a perfect insulator.

 

[jaydnul]

Leaking through the air in a matter of seconds each time it arcs?

 

[sophiecentaur]

The sphere leaks less charge than the angular cage. The sparks show there is a continuing Potential Difference (like in a potential divider)

 

[jaydnul]

How is it leaking that quickly through the air? Air is a dielectric, which means it is polarizable but doesn't carry and current (unless it ionizes, but i don't see any arcs going to ground), right?

 

[sophiecentaur]

i don't see any arcs going to ground),

If the sphere keeps discharging then there must be current leaking somewhere. You can get fine corona on corners which you may not actually see except in a darkened room. Or, of course, there could be a resistive path through the support of the faraday cage.

 

[jaydnul]

Ok thanks!