Re: Speed of Streamer formation

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

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

Good idea...
And though the temperature might be low, it's probably still pretty hot..
Once it cools down to a few thousand K, the radiation cooling's going to
drop off real fast (T^4)... but 1000K is still pretty hot.

Tesla list wrote:
> 
> Original poster: "Bert Hickman by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
> 
> Jim, Dave, and all,
> 
> There's some evidence that the next leader follows the same channel as
> the previous from bang to bang  due to residual hot air left in the
> previous leader's channel. While the channel air temperature is much too
> low, and duration too long, to convincingly explain consecutive
> breakdown on the next bang from  residual ions, residual channel heat
> may simply make the air in the former channel less dense. Since less
> dense air has a lower breakdown voltage than the surrounding colder air,
> the next leader finds this path the "weakest link", and the next leader
> preferentially follows the "warm" path blazed by the previous leader.
> 
> Best regards,
> 
> -- Bert --
> --
> Bert Hickman
> Stoneridge Engineering
> Email:    bert.hickman-at-aquila-dot-net
> Web Site: http://www.teslamania-dot-com
> 
> Tesla list wrote:
> >
> > Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <davep-at-quik-dot-com>
> >
> > Tesla list wrote:
> > >
> > > Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <jimlux-at-earthlink-dot-net>
> >
> > > > I suggest that gradual growth of streamer length may be due
> > > > to increasing number of ions present in the immediate
> > > > vicinity.  Recombination (and air mixing) take a finite
> > > > period of time...
> >
> > > The "burning" question.. how long?
> >
> >         Dunno.
> >         I Assume the answer is out there, at least for some gases
> >         at some temperatures....
> >
> > > Clearly, it's not just the cooling of the plasma until it stops
> > > conducting (which happens VERY fast, considering that there's a
> > > pretty sharp knee in the conductivity vs temp curve).
> >
> > > Although, the radiation cooling (probably dominant?) does go as T^4,
> > > so it might stay pretty hot, but not radiant (at least in visible..).
> > > Hmmm..
> >
> >         Indeed.  I suggest the issue is electrons dropping back down
> >         the orbital levels, which can be cooling, per se, or other
> >         factors.  (Note that lifetime of 'population inversion'
> >         (electrons in high orbitals) is critical to laser function.)
> >         More so: the ions involve electrons physically separated from
> >         atoms.  They need to travel home.  This CAN happen quickly,
> >         or slowly (milliseconds, longer) depending on pressure, gas, etc.
> >
> > > This is an area that isn't covered by much of the spark literature.....
> >
> >         I'd look into physics work on conduction in gases: Cobine, Gaseous
> >         Conductors.