[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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



Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

The time it takes for top terminal "energy" to reach a maximum has been noticed with DRSSTCs. Apparently, faster energy rise times give better streamers.

http://drsstc.com/~terrell/modeling/

ScanTesla calls this "LERT" for Load Energy Rise Time. But this is the top terminal energy buildup over the first few cycles of a single burst rather than the time it takes for the terminal voltage to build up in a cycle. The voltage during a single 1/4 cycle is Vo(t) = Vm x SIN(2 x pi x Fo x t).

The buildup of load energy is shown here on page 8.

http://drsstc.com/~terrell/modeling/BigCoilDRSSTC.pdf

LERT is defined as the time it takes the load energy to go from 10% to 90% of the maximum.

If this should be called "Critical Rise Time" rather than "Load Energy Rise Time", I can change it.

BTW - I still need to update ScanTesla and write better instructions still....

Cheers,

        Terry


At 08:03 AM 1/14/2006, you wrote:
Hello Marco.

> Original poster: "Marco Denicolai" <marco.denicolai@xxxxxxxxxx>

>  > 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".

for single pulse (or step) - yes, there is such thing like "optimal
rise time", but how this can be applicable to tc, where the full
discharge length forms from more that one subdischarge?
suppose that with optimal rise time you need 10 bangs for breakdown of
gap of some arbitrary length.
now your rise time is smaller than optimal - first discharge would be
shorter than the optimal one, but first bang leaves an ionised path
(like all the rest subsequent bangs), so after 10 bangs you`ll have a
long ionised chanel and you don`t need optimal rise to break this
channel - right? of course this channel would be shorter than the gap
we want to break, but now you can add 11-th bang, 12-th bang and so on.
and i think that in the end you would have practically the same length
of spark as in case of optimal rise time, the difference would be only
in length of the last bang.
so if for example your spark consists of 10 "optimal" bangs, and my
spark consists of 14 "bad" ones and each of them is 1.5 times shorter
than the optimal, my spark would be only 6.7% shorter?

>  > 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.

is anyone able to get the rise time too big for streamer formation at
all, coz streamers have such thing as minimal velocity?
something like this - in air for positive streamers minimal rate of
voltage rise is about 45GV/s, so for tc with say 800KV output we
must mantain Fo more than about 9KHz?

-----
Let the bass kick! =:-D