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Re: Analysis of streamer observations

Hi,

At 01:59 PM 5/21/99 -0400, you wrote:
>Hi Terry, All,
>    I noticed the following things from your streamer current scope
>waveform:
>
>1.  When the first voltage rise begins on the toroid and reaches a
>voltage of approximately 50 kV there is a large current spike for the
>streamer waveform.  Is this real or an artifact?

At the first instant, when the gap first conducts, there is a huge high
frequency burst that I belive is caused by parasitics suddenly being
drained into the gap.  Like the gap capacitance suddenly being shorted.
This causes a very powerful high frequency burst.  I have been triggering
my equipment off this burst from a small plane wave antenna for about a
year now.  It is very high frequency and very real.  Perfect for scope
triggering!

>
>2.  After the spike, the streamer current waveform appears to be 180
>degrees out of phase with the voltage on the toroid for about 1/2
>period.  Not quite sure I understand this.

In the first 10uS, the streamer does not appear to have started yet.  Then
at 12uS, the streamer seems to have suddenly started and the voltage
waveform seems to be a little drained by it.

>
>3.  At about 10 us after the spike the streamer current begins to
>track the toroid voltage.  The waveform appears to be distorted or
>nonlinear.  Could this be from streamer channel heating effects?

Before 10uS I don't think the streamer has started.  There is very little
current flow out of the terminal.  I suspect the spike is caused by
suddenly beginning to short out the E-fields in the streamer path.  Sort of
like shorting a cap in air.

>
>4.  At about 20 us after the spike the streamer waveform appears to
>become more sinusoidal.  There appears to be a very slight saw tooth
>(RC charge and discharge) curvature to the waveform.

There is a noise level in the waveform you can see in the none firing
areas.  This may be distorting fine detail and making that sawtooth form.
Hard to tell.  It may be something profound, but I don't know...

>
>5.  Some of the peaks appear to have spikes.  Could these be
>oscillations within the streamer itself?  Alfven waves?  Digital scope
>effects?

I am pretty sure they are real.  I have no idea what an "Alfven wave" is??
I assume the rough spikyness is like dart leaders or the streamer being a
bit unstable.  Perhaps it is crackling a bit...  I don't know...

>
>6.  At about 32 us, 34 us, 38 us, and  43 us there appear to be
>shoulders or plateaus on the sides of the peaks.  Could this be from
>branching of the streamer?

Your guess is as good as mine....

>
>7.  From 60 to 75 us the sawtooth waveform shape in the streamer
>current becomes pronounced.

Yes,  A little my be due to the sampling or digital nature of the picture.
Hard to say... 

>
>8.  At around 200 us the streamer current appears to extinguish below
>about 100 microAmperes.  Could this be the measurement noise floor?

It looks like the streamer loss goes away and the terminal continues to
oscillate with much lower loss as shown by the voltage waveform.  It is a
little hard to say because the gap may have quenched too.  It looks like
the streamer stopped at the same time the gap quenched.  I would not go
basing a whole lot on this single scope capture though...

>
>9.  The streamer current waveform appears to be symmetric w.r.t. the
>axis whereas the toroid voltage waveform appears to be biased
>positively.  The baseline at the beginning of the trace appears to be
>offset also.  Is this a measurement artifact?  Is this bias polarity
>really positive?

The voltage bias is common.  I think it is because negative voltages arc
much easier than positive voltages.  This voltage bias on the terminal is
very common.  I assume if you integrate the current, you will find that it
flows more in one direction than the other.

>
>10.  After about 100 us the streamer current appears to extinguish
>completely.  The voltage on the toroid appears to ring with a very
>steady amplitude indicating a state of high Q.  This ringing at about
>+ and - 40 kV appears to not cause any observable streamer current.

The streamer stopped and the gap quenched.

>Is this a R.O.C. limit for your salad bowl toroid?  B.T.W. I replaced
>my silver soldered salad bowls with a real toroid (24 by 4 maybe) and
>the spark length doubled with minor retuning at the same input energy.
>It would be very interesting to see comparison waveforms between the
>two types of terminal.  It would also be interesting to see streamer
>current measurements with various types of discharge electrodes
>ranging from needle points to spheres of different sizes.?????

This is two salad bowls taped together with that fancy copper tape stuff.
It makes it easy to change batteries and stuff.  I am going to build
another current probe that simply sets on any terminal to measure anything.
 However that project is about 6 months behind :-(

I don't know the answer to many of your questions.  I think the scope
waveforms are very accurate given the noise floor.  Such things could use
more study obviously.

Glad your enjoying the pictures!  Which I knew more about what all the
things are...

Cheers,

	Terry


>
>
>----- Original Message -----
>From: Tesla List <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Thursday, May 20, 1999 7:05 PM
>Subject: Re: Secondary Theory (Was Bipolar Coil)-Heretical view
>
>
>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>It is my understanding that these are all streamers.  I know mine
>were.  I
>cannot verify if Greg's were???  When a streamer hits a grounded
>target the
>currents are giant and the system is instantly drained!!!  Another
>paper I
>never got around to writing yet...
>
>Terry
>
>
>>http://www.peakpeak-dot-com/~terryf/tesla/experiments/modact/modact.html
>>
>>in the very last photo, you can see my current to the arc was also at
>>the
>>fundamanetal of 110kHz in my case.
>>Terry
>
>
>
References: