Rectifying a TC (a bit?)

Tesladownunder, Sun Apr 08 2007, 03:32AM

We know that TC's don't make your hair stand on end like a van der Graaff generator. This is because charges don't accumulate but are dissipated in the reverse direction continuously with the spark ring down which occurs at the TC frequency of perhaps 100kHz.
This became obvious to me with the non-performance of my 14 foot spinner.

Consider a spark from a needle point to a plane surface. The voltage at which this breaks down is lowest when the needle is negative. From my experiments, this is perhaps as much as 1.4 times as great as the opposite polarity. Unlike a diode, though, when the spark fires, the diode is short circuited (in both directions) and any accumulated charge is lost.

Consider the situation where there is just a corona, depositing charge without the spark. It may be possible to accumulate some charge. This might show up with the equivalent of a head full of hair which is an electrometer just two foils together which separate if a constant DC charge is present.

My experimental setup is based on Coke Zero cans. (I have not replicated this with any other cans like Coke plain or other generic Colas ). By twisting and cutting the ringpull, a sort of needle point is obtained. This is brought up to 1.5cm from another cans base which is concave. In this way a string of cans can be made, each with a polarising gap and with few sharp edges exteriorly to generate spurious corona. It is run from my mini TC (2 inch sparks) connected to the right can. Earth is the left. Note that this is below sparking threshhold.

By the use of an aluminium foil electrometer I can show (with constant TC output)
Pic 1 Eathed side: No electrometer reading (only few mm)
Pic 2 Central can: Electrometer shows wide separation
pic 3 TC side: Electrometer shows mild separation

I interpret this to show some charge accumulation, presumably positive, since this is the charge that can't escape.

Anyone have any thoughts or how to progress this?

TDU