RE: Critical rise time (RE: Terry's New Plane Wave Antenna)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Leigh Copp" <Leigh.Copp@xxxxxxxxxxx>


Just a thought with regard to the comment that "Rise time implies
waveform shape, that is "fo"." I think that you meant the frequency
-content-, and not fo.

The sum of the Fourier components of the wave each impart their own
contribution on the rise time. The bandwidth of the system can be
calculated as 0.35/risetime, but this would be the highest frequency
components only. Fo of the system, as has been well discussed in this
group, is 1/(2*pi*sqrt(L*C)). The higher order harmonics of the system
however, are what contribute to the "steepness" of the wave front. These
are going to be multiples of fo.

The current we are applying to our TC's is resonant at some fo and
modulated by our spark gap (which itself is very rich in 3nth order
harmonics) and it's own pulse rise time. Rotary spark gaps or SSTC's are
modulating by the break rate additionally.

If anyone is brave enough to apply the convolution theorem to that one
the actual system bandwidth can be expressed in terms of break rate and
fo.

Leigh



-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: January 13, 2006 2:28 AM
To: tesla@xxxxxxxxxx
Subject: Re: Critical rise time (RE: Terry's New Plane Wave Antenna)

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Thankyou Marco,

Maybe someday one can quantify this range of rise times by a range of
frequencies.  Im now wondering if the "critical rise time" is fixed
or dependent on some other factors.

Gerry R


>Original poster: "Marco Denicolai" <marco.denicolai@xxxxxxxxxx>
>
>Hi Gerry,
>
> > -----Original Message-----
> > From: Tesla list [mailto:tesla@xxxxxxxxxx]
> > Sent: Friday, January 06, 2006 19:04
> > To: tesla@xxxxxxxxxx
> > Subject: Re: Terry's New Plane Wave Antenna
> >
> > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> >
> > Hi Marco,
> >
> > What you are saying is one can get the rise time of the topload
> > voltage too small for optimum streamer formation???
>
>Yes. The optimal rise time is often called "critical rise time". It is
the
>one for which time-to-crest is equal to time-to-breakdown.
Time-to-crest
>means time for the waveform to reach its maximum value. Sorry for the
odd
>words but this is the naming often used in the literature.
>
> > If so, does
> > this relate directly to "fo" of the coil (rise within one RF cycle)
> > or to the coupling coefficient "k" (affects the peak to peak
> > rise).
>
>Rise time implies waveform shape, that is "fo".
>
> > Also, I presume there is an upper limit on the rise time for
> > optimum streamers as well.
>
>Probably, I mean for TC kind of bangs. For single surge pulses (like
those
>used in classical literature) using larger rise time gives, of course,
>larger time to breakdown.
>
> > What other factors affect these boundary
> > constraints??
>
>I hope to shed some light on this in my PhD work, if it ever gets done
:)
>
>Best Regards
>
>