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Re: [TCML] still stuck at 36

Hi John,
The single gap with low loss sounds reasonable. The idea of quenching sluggishly, well, some variation is possible, but the consequence is not a cap charge issue. The charge time on a typical coil versus the maximum energy transfer time is over 1000x. For my 4.5"D coil, a 12/60 NST charging a .0188uF cap, charge time is 18.8ms for 120bps operation versus a 17.16us for complete energy transfer (3.9 cycles at 230kHz). If we quench slowly, the cap has all day to charge since the 17us makes little difference (0.01% of charge time).
A quench variation entails a quenching early scenario which would leave a charge on the cap (and energy in the cap). The cap would then charge to breakdown more quickly to the next due to the charge left on the cap (the line between A and B just got shorter, bps increases, spark length diminishes). But this also states that all the energy in the cap did not make it through the transfer (this is why spark length decreases and not so much the bps which was simply a result). I think nearly all of the energy transfers, and so much so, that the voltage left on the cap is insignificant in the same fashion as the ratio between cap charge time and energy transfer time, and more so in a static voltage clamping gap as opposed to a rotary.
Energy transfer time does make a difference of course (energy and time). But the gap cannot affect the energy transfer time significantly by quenching early (but it can by preventing extensions of the transfer time in an extremely bad situation). This would be due to gap impedance.
Energy transfer time is based on the mutual inductance and frequency. For my 4.5"D coil, reactance as based off of the mutual inductance is 123 ohms. If the gap was ridiculously lossy, it's resistance would add to this reactance. In a completely theoretical case where the gap resistance was equal to this reactance, the transfer time would be double. It is still insignificant regarding cap charge time. However, the em force enveloping the secondary would certainly be reduced (time and energy), and this would affect energy stored in the top load.
But now for the gotcha! Gap resistances are less than 1 ohm. So gap losses are not affecting energy transfer times. I think it's all about simple power losses at the gap that are the real cause of pain and suffering with spark lengths which is why significant air cooling drastically improves any static gap style (some styles are better than others at accomplishing this). There is always the issue of too high a velocity at the breakdown point that blows out the spark. This is a quenching early issue, which of course doesn't transfer "all" the energy in the cap and thus we see spark lengths diminish and bps rise. This is why some find using a variac on the air voltage is not always best at 100%.
Hope I'm making sense. Sorry for being long winded, but it's one of those "devil in the details" subjects. 
Best Regards,
Bart

futuret@xxxxxxx wrote:

I think what makes a hyperbaric gap perform well is that it's
a single gap.  This makes it a low loss gap.  Once you have a
low loss gap then all that's needed is to quench it adequately.
Since a single gap is harder to quench than a multi-gap, this
is why a good amount of air flow is needed.

The air flow is
also needed to cool the electrodes.  If there's not enough
air flow the gaps may run too hot and may begin to power arc,
or quench very sluggishly.  If a gap quenches too slowly,
then less time is available to recharge the capacitor and
output suffers.

If there's too much air, then
the gap may fire intermittently with a sort of stuttering
action and this cuts the spark length too.  It's not really
over-quenching, it's simply erratic firing in the first place.
It's not that the gap quenches too fast, rather it's that
the gap does not fire consistently.

John
--


-----Original Message-----
From: DC Cox <resonance@xxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tue, 27 Jan 2009 4:58 pm
Subject: Re: [TCML] still stuck at 36
It's not clear why to me either. My best guess is better cooling due to the 
high velocity air, and perhaps increased turbulence
around the ends of the copper pipes.
I know that most coils performance jumps in amazing quantity of spark output 
when the hyperbaric gap is used.  I have never used it above 4 kVA as a
single gap, but did some experiments at 7 kVA with a dual series hyperbaric 
gap and it seemed to work as good as a small rotary.
Perhaps looking at scope ringdowns with and without a hyperbaric gap might 
provide some clues.

Dr. Resonance




On Tue, Jan 27, 2009 at 1:51 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
I don't disagree that hyperbaric gaps work well, but I'd like to be 
clear
on why. Too often on this List, the word "quenching" is used 
incorrectly.
My measurements showed conclusively that hyperbaric gap losses were 
lower
than in a sucker gap, but I made no attempt to measure actual 
quenching.
Quenching is unrelated to gap losses and refers to how many pri-sec 
energy
trades occur before the gap extinguishes. In fact, I think that 
typically,

lossy gaps (at least multi-segment gaps) have superior quenching.
So, have you seen evidence that actual quenching, as observed on a 
scope,
was superior with the hyperbaric gap? Was this with free-air 
streamers or

grounded (connected) streamers?  Seems like a very difficult thing to
accurately compare between two systems.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of DC Cox
> Sent: Tuesday, January 27, 2009 1:31 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] still stuck at 36
>
> Bill:
>
> What was your maximum spark before you used the hyperbaric sparkgap?
>
> Also, put a variac on the vac. cleaner motor, and fine adjustment 
of the

> speed will increase your output even more.  Usually best output
> around 75% of the variac.
>
> I know they work great.  They always increase your sec spark output
> dramatically which means we have been underquenching
> with most of our previous designs.
>
> Dr. Resonance
>
>
>
>
> On Tue, Jan 27, 2009 at 5:50 AM, Bill Bohn <b.jbohn@xxxxxxxxxxx> 
wrote:

>
> > I built the hyperbaric gap as described WOW!Now I get 44" I am 
using a

shop
> > vac for suction.I am using 5 of the 6 strings of caps.I think I 
did

some
> > damage
> >
> > To my 5-1/4 coil.Now I have a 6.625" secondary wound 26.5" 1060 
turns.

Top
> > load is 4.5x18 toroid and a 7" sphere.Seems best with the primary
clamped
> >
> > At turn 5.The spark sounds somewhat eratic and choppy.IT will 
smooth

out
> > some by adjusting the spark gap closer at the loss of streamer 
length .

> >
> > What is the method of measuring BPS?IT doesn't seem to sound 
right.The
> > coupling between primary and secondary is 0.I am going to put the 
6

strings
> > of
> >
> > My mmc cap in but I think it will be best tuned at about turn 2 
and

become
> > even more erratic.
> >
> > I am getting positive results and thank everyone for all the 
ideas and

2
> > cents worth.
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
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