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

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Bert,

At 09:47 PM 12/6/2002 -0600, you wrote:
>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.


Oops, you right :-)  CW coils have hardly anything to do with inductance 
ratios.  It is a Q effect.  Caught me ;-))



>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 220k + 1pF of capacitance per foot of streamer length things does not 
apply to CW coils.  The notes at:

http://hot-streamer-dot-com/TeslaCoils/MyCoils/CWCoil/CWImpedance.txt

Probably give a far better idea of CW coil streamer impedance but this is 
just a one time observation so I don't know how much different coils vary.

Cheers,

         Terry




>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