Re: Spark Gap VI Scope Capture

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Once I low pass filtered/decimated the data, it looks like V and I line up 
quite nicely.  The V transients are right at the I zero crossings.

The overall baseline shift during the pulse is interesting.  I wonder if 
it's just representative of some AC coupling.  Essentially you've got 
3000V, then zero volts, (ignoring the LC ringing and transients)and maybe 
the voltage probe system is a bit overcompensated so you're getting 
negative overshoot.
The overshoot looks like about 10%, peak.

The little spikes at the beginning of each conduction interval might be the 
resonance of the spark gap wiring etc, that you observed in frequency 
domain several years ago. The overshoot looks like about 80-100%, and it's 
real fast, so it might also be a probe compensation artifact.  Very much 
shorter timescale, though, than the big overshoot mentioned above.  It 
could also be a termination thing. When I look at the unfiltered data, the 
overshoot is a lot bigger... 500%, making me think very capacitance 
coupling the edge through.

The final ringing is interesting too.. a much higher frequency (1 MHz?) 
than the other stuff. Perhaps a parasitic in the gap circuit after it has 
finally quenched.

At 01:09 PM 5/20/2003 -0600, you wrote:
>Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
>
>Hi Jim,
>
>The scope is a 100MHz Tek 3012.  The current probe is a Pearson 101 only 
>goes to 4MHz for -3dB so maybe there is phase shift there.  I could 
>probably go to a 20MHz type 411.  The voltage probe is a Tek 6015 should 
>be good to 75MHz.
>
>Cheers,
>
>         Terry
>
>At 11:56 AM 5/20/2003 -0700, you wrote:
>>This is kind of odd...  It looks like there must be some phase shift 
>>between the I and V measurements, since presumably, I and V should be 
>>reasonably in phase.  I wonder what happens if you low pass filter the 
>>data (say, to 5-10 times the Fres) to get rid of the HF spiky stuff, so 
>>that you can get an idea of the bulk properties.  I'll have to download 
>>your raw data and do some fiddling..
>>
>>
>>At 12:32 PM 5/20/2003 -0600, you wrote:
>>>Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
>>>
>>>Hi Jim,
>>>
>>>Looks like this:
>>>
>>>http://hot-streamer-dot-com/temp/03-05-20-01.gif
>>>
>>>I tried over smaller times spans but it did not really seems to show much.
>>>
>>>Cheers,
>>>
>>>         Terry
>>>
>>>At 07:03 AM 5/20/2003 -0700, you wrote:
>>>>One might want to plot V vs I for the gap... While time domain behavior is
>>>>interesting, I'd be interested to see the VI characteristic for the gap...