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Re: TC Electrostatics

You wrote: 

snip
>>
>> Bert and Richard ,
>>
>>Our work shows that the collecting electrode takes on negative 
>>charge regardless!  An ES voltmeter can't make this determination.  
>>An electrometer can.  Note that we have recorded DC output even from 
>>a non-discharging disruptive system.  This output is of a much lower 
>>level than the discharging system, but there nonetheless!  The 
>>electrometer is a pivotal instrument in quantitative measurements of 
>>such systems.
>>
>> Richard Hull, TCBOR
>
>Richards,
>
>I can understand how a build-up of negative charge might occur based
>upon the higher mobility of free electrons versus ions. I was _really_
>stumped about how a positive charge build-up could be occuring! Thanks
>for the additional clarification. Still certainly a lot of mystery 
>about this phenomenon however...
>
>-- Bert --
>

12/1/96

I recently obtained a 20kV electrostatic VM at a hamfest.  After 
Richard suggested ESVMs measure both DC and AC, I opened up the 
cabinet. Essentially there are two capacitor plates - one fixed and one 
movable. The movable one is attaced to a coiled hair spring and has a 
moving indicator attached.  The mechanism is simplicity itself.  
Oppositely charged plates experience attractive force.  If the fixed 
plate is at ground potential then the movable plate is attracted 
whether it's positively or negatively charged in reference to the 
grounded plate.

I tested my ESVM with 1/2 of a 9 kV neon with the center grounded and 
connected to the ESVM.  The high voltage side was coupled to the ESVM 
by an air cap with a gap about 1".  Sure enough the ESVM measured the 
AC high voltage.  Just as Richard predicted.

I then ran a series of experiments with the same TC set up and 14" x 
14" Al target.  These are only qualitative at present, but the the 
results are very interesting.  I plan to repeat the attenuation 
experiments.  

I put a bypass cap across the ESVM to ground to get rid of the TC AC  
component.  The ESVM charging was slower and not as high, but it still 
charged to several kV.  The ESVM holds a charge after charging is over. 
I measured this charge with a 40 kV probe with both a digital and high 
impedence electronic voltmeter.  Both indicate the charge is positive.
I measured at various TC voltage inputs, used different caps and 
various distances (R).  Always positive charge.

I next conducted the same experiment using a 0.02 mF mica cap instead 
of the ESVM.  Same results - positive charge.  Tested several different 
caps and same results.  Switched around leads to the TC primary.  Still 
Positive. 
 
Here's one everyone can confirm.  Connect the negative lead of a 
digital volt meter to system ground and hold on to the positive lead.  
Fire a small TC at low power at a safe distance.  You are now a 
capacitor plate.  If you have an auto ranging DVM it will tell you if 
you have collected a positive or negative charge.

Next I put two 12kv PIV 550 mA microwave diodes in series with the 
ESVM. I put two together for approximately 24 kV PIV.  When oriented to 
permit the positive AC component to conduct the ESVM charged very fast 
and high.   When oriented to permit only the negative AC component to 
conduct, the ESVM charged slowly and lower, but it did charge.  When 
four diodes - two back to back to two others - were placed in series 
with the ESVM all AC was blocked.  Charging was very similar to 
bypassing with caps.  The four opposing diodes actually permit passage 
of electrostatic charge but not AC current!  This is amazing.  These 
experiments were repeated with the mica cap with similar results.

I make the observation that with this particular set up TC 
electrostatic discharge power predominates over EM discharge, since the 
capacitor or ESVM is charged positively (albeit slower and to a lower 
value) when only the negative EM component is conducted and summed with 
the electrostatic component.  Perhaps the TC electrostatic component 
creates the ionized arc channels first and the EM componet then 
conducts in this lowered resistance channel.  This could explain some 
of behavior and questions we have had about theses arc channels.  Isn't 
lightning sometimes also modeled on this observation?

My experimental data strongly indicates positive charging for my 
system.  This does not invalidate R. Hull's findings of negative 
charging on another system.  There are endless variables in these 
systems.  These TCs emit an explosive scalar wave.  They are also 
scalar translators and these scalar waves are immediately reconverted 
back to EM.  At this point our knowledge is limited and no one knows
for sure how this is accomplished and what all the variables are.

Bert you are correct that for a positively charging system, electrons 
are not likely to be the charge vector.  The fan air stream is 
perpendicular to the path from the TC terminal to target.  The idea of 
the fan is to remove any ions or charged particals.  Ozone and ions 
move more slowly, but electrons are accelerated much easier and 
probably won't be affected by the air stream.  However, since the 
target is being charged more positively, electrons should be moving 
from a flat 14" x 14" surface to a point surface (actually a 1 1/2" 
brass ball).  Not likely.  If charging negatively, electrons would be a 
more approriate vector.

R. Hull does your Keithly electrometer measure both positive and 
negative charges.  Coulombs may have either positive or negative 
charge.

RWW