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Re: streamer impedance



Subject:      Re: streamer impedance
       Date:  Mon, 19 May 1997 12:36:48 +1200
       From:  "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization:  Wellington Polytechnic, NZ
         To:   tesla-at-pupman-dot-com


Hi theory group :)
                   thought I might have a quick shot at this....

>   From:  pierson-at-ggone.ENET.dec-dot-com
>     To: 
>        
> 
> >> Do you think that the streamer impedance can change as fast as 
> >> the current in the sinusoidal waveform?
> 
>         I should certainly hope so.  The current determines the
> impedance,
>         to some extent...
> 
>         (Interesting challenge to computer model THAT.  8)>>
>         [I ASSume it could be done, but its not gonna be trivial..])
> 
>         regards
>         dwp

Starting point: we know primary ringdown is linear and a linear 
decrement has also been observed with secondary discharges. To date 
my thinking has been that Vgap conducting is nearly constant. I will 
measure this in due course (I could be totally wrong, BUT, the 
ringdown is linear). According to the picture I have, Rgap = k/f(ip)

   So Rgap = Vgap/ip(t)        and we know ip(t) is sinusoidal.
   i.e. ip(t) = Ip.sin(wt)     where Ip is peak current
   => Rgap = Vgap/(Ip.sin(wt))
   => Rgap = Vgap.cosec(wt)/Ip

and Ip itself changes as ringdown progresses due to loss/transfer to 
secondary. This is definitely a first-order shot at it.
     I would dearly love to know or develop a formula for the pri-sec 
transfer as a function of time. Bert's figures suggest there is 
indeed an inertia type of process at work there. Much more to be done.

Musings, comments welcome,
Malcolm