Re: SSTC Pspice Simulation - Valid or changes needed? ? ? ?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Terry and Dan,

A couple of possibilities...

1. The V2=V1*Sqrt(L2/L1) relationship was actually derived using 
Conservation of Energy and an assumed fixed "bang size". This approach is 
really not appropriate for a resonator being driven from a CW or pulsed CW 
source that can continually add energy into the oscillating system from 
"outside".  For this case, it's more appropriate to use Q-multiplication to 
estimate pre-breakout output voltage. Under CW excitation, secondary 
voltage will build up until secondary losses (per cycle) balance power 
being added into the TC primary (per cycle). Since pre-breakout Q is 
normally quite high (>=100) in a well designed coil the multiplication 
factor is also of similar magnitude. If you're seeing 12 inch discharges, 
you are definitely getting significantly more than 20 kV output.

2. Terry's model simplified corona and streamer losses by assuming constant 
corona loading, but was actually estimated by by looking at "no breakout" 
ringdown of the secondary. It's very likely that Rcorona of 250 ohms is 
artificially depressing the model's secondary Q during (pre-breakout) 
ring-up and artificially reducing peak voltage reached by the SPICE model. 
In reality, secondary Q should remain high during most of the ring-up. It 
should begin to measurably decline only after initial corona breakout 
begins to sap additional energy from the secondary. However, significant 
reductions in secondary Q should only be evident after full fledged 
streamers and leaders begin to tap significant energy from the 
secondary/toroid system.

The secondary model may be more accurate by removing Rcorona. However, it 
may also be appropriate to include an R term which accounts for additional 
AC resistance of the resonator at Fo (to account for skin and proximity 
effects in addition to the DC resistance of the resonator). The effective 
AC resistance of the resonator can be estimated by calculating resonator Q 
(such as base-driving the resonator from Terry's pinger, and measuring 
ringdown response).

Best regards,

-- Bert --
-- 
Bert Hickman
Teslamania, from Stoneridge Engineering
"Electromagically" (TM) Shrunken Coins
http://www.teslamania-dot-com

Tesla list wrote:
>Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>Hi Dan,
>Hmmmm,  "seems" kind of low to me too but can't say for sure.
>If we look at it as a pure transformer:
>V2 = SQRT(L1/L2) V1
>Gives about 10kV peak to peak.  So that seems to support a lower 
>voltage.  However, the sparks look like more than 10kV to me ;-))  I would 
>hook up a current probe and stuff but I am not sure what you have there to 
>test high voltage things.  Models are neat but they can always us a little 
>solid verification especially when the results don't feel right.
>Cheers,
>         Terry
>At 11:14 AM 12/6/2002 -0500, you wrote:
>
>>Does the voltage output of my SSTC PSPICE simulation look valid????  It
>>reports about a 20kVDC peak-peak output voltage, but
>>to me that seems kind of low.  Or is it as in real life, streamer length is
>>about 12 inches.
>>
>>http://www.spacecatlighting-dot-com/sstc_pspice.htm
>>
>>Am I missing something?
>>
>>Anything I could add to my tesla resonator model to improve it????
>>
>>Any help appreciated.
>>Thanks
>>
>>Dan
>
>