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Re: Coupling vs secondary voltage chart

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Malcolm,

At 12:22 AM 6/17/2005, you wrote: 
Hi Terry,
          Nice work on your program. I might be able to explain one
or two anomalies Steve noticed with primary current.

     I decided to plug my large SG coil figures into the program and
varied only the coupling from 0.05 to 0.25. "New Highs" were reached
as the coupling increased right up to k = 0.25 (the limit I set).

 _However_, it is clear from several runs that the outputs are
*heavily* dependent on the figure given for Rp. Intially I tried 2
Ohms which got barely 1J out of 3.2J to the secondary. I then tried
0.5 Ohms which did somewhat better which ended up with 1.95J (which I
think is still much too low) and Vc about 318kV which again I think
is on the low side (based on singleshot sparklength - I estimated
about 340kV).

      The moral of the story is that the primary resistance specified
is crucial to ouput accuracy. Finally, I did a run with Rp = 0.1
Ohms. Now Vc looks more in the ballpark (about 350kV) and load energy
got to 2.755J (certainly believable).

Rp is indeed very important. I had measured it before on my big conventional coil as 3 ohms and that is what I used. I have just been guessing at Rp for the DRSSTC case at 0.5 ohms. Rp includes spark gaps losses.


      Finally, I did another run, this time allowing k to climb to
0.5. Still the program kept finding New Highs, the last occurring at
k = 0.499. By this time though, load energy had dropped to about
2.74J despite Vc reaching about 387kV.

The coil is becoming more like a conventional transformer at high K values. Mine seems to peak at about K=0.6


Some comments on the program:
      It would be nice if instead of reporting a bunch of new highs,
the program simply gave an output of best results (there might be
more than one) at the end of its run.

I like to update progress so I can watch it and stop it if something is going wrong. The screen and file updates slow it a bit but I like to see what is going on. I may input flags to supres various outputs. It gets bad if the files get to be like 100Meg on big runs. Right now I need to see a lot just for diagnostics.

      I cannot understand how the coil gets to a higher output
voltage with a lower secondary energy.


High coupling,  It is just a single shot pulse transformer.

      I didn't see any mention of sparklength in the output. This
would depend on breakrate and I didn't see any room for entering this
in the input file.

The outputs are BPS independant. Since the DRSSTC really can have any BPS rate, I left BPS stuff to the user. You just multiply the bang energies by the BPS to get power. For primary current, you multiply by SQRT(BPS).

For the Freau formula:

Spark length = 1.7 x SQRT(BangEnergy x BPS)

      For disruptive coils it would be nice if the program could
calculate a figure for Rp based on some function of primary current
(averaged if that is what is called for). That way there would be no
guessing.


How?


     I would greatly appreciate you comments on any or all of these
points. I applaud the efforts of yourself and all those who have
contributed to the making of this program.


:-)



Cheers,

        Terry


My regards to all of you,
Malcolm