TSSP: List Archives

From: "Terrell W. Fritz"
Date: Thu, 28 Feb 2002 19:09:45 -0700
Subject: Re: [TSSP] Ion Cloud Loading

Hi Malcolm,

I seem to have more than enough equipment to do this (almost an obscene
amount in fact ;-))

I set up my 0-50kVDC Bertan X-ray power supply and my little battery
powered (and cheap if something goes wrong) TCT Tesla Coil Tuner (a simple
adjustable square wave generator) in series between ground and the coils
base connection:

http://hot-streamer.com/TeslaCoils/Misc/IonCloudTest/HVDCPower.jpg

http://hot-streamer.com/TeslaCoils/Misc/IonCloudTest/Coil.jpg

Thus, I can inject the ~250kHz signal into the coil riding on top of say
50kVDC :-)

I then set up my antenna and scope to measure the resonant signal.  The
scope was set to read Vrms over many cycles to give a nice stable reading:

http://hot-streamer.com/TeslaCoils/Misc/IonCloudTest/Antenna.jpg

http://hot-streamer.com/TeslaCoils/Misc/IonCloudTest/Scope.jpg

So I could detect if the signal strength dropped (from coil detuning) as
the coil was charged from 0 to 50kVDC.  The "Q" of the coil setup was about
15.8 (253/16).

Here is the measured signal strength of the resonant tuned signal as a
function of terminal voltage.


Voltage (kVDC)	Signal Level (Vrms)
0			2.28
5			2.28
10			2.28
15			2.28
20			2.28
25			2.29
30			2.29
35			2.29
40			2.29
45			2.29
50			Corona Inception

The slight change in voltage seemed real but was at the edge of the
system's measurement capability and may have been due (probably) to the
power supply's switching signal leaking through.  At 50kVDC you could hear
corona breaking out pretty heavily so I stopped in fear I may pop the TCT.

In conclusion, I found no evidence that the coil's DC potential had any
affect on the system's resonant frequency

Cheers,

	Terry


At 08:39 AM 2/28/2002 +1300, you wrote:
>Hello all,
>           For a long time now, many have suggested that an ion cloud 
>hanging around the secondary terminal necessitates detuning the 
>primary downward somewhat to compensate. I have long doubted this 
>mantra (without proof) but have devised a relatively simple test that 
>could be performed to establish where the truth lies. My doubt arises 
>as I think that any detuning of the secondary can be explained (I 
>think) by capacitance (and resistance) added visible streamer length 
>alone.
>       The test does not involve spark production (important). 
>Instead, one uses the usual setup of a signal generator and aerial 
>probe to monitor the secondary ringing alone, and then introduce an 
>ion cloud around the terminal using some other devices (like ozone 
>generators. UV generators etc. Any significant shift in secondary 
>frequency should be quite observable. 
>       I think this is an appropriate forum to check this out and add 
>to the knowledge base. Is anyone equipped to easily do this test?
>
>Regards,
>Malcolm
> 


Maintainer Paul Nicholson, paul@abelian.demon.co.uk.