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

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

Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>



So you are basically saying that the Q of the system is very high during a
pre-breakout condition and that the voltage
will rise to very high voltages before break-out occurs.

Any suggestions or ideas on how to accomodate this in a pspice model????

Perhaps some sort of equation block which detects some threshold voltage
level before switching to an alternate
circuit which is the equivalent circuit during discharge.

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