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Re: Results of new single static gap

to: Russ

I wanted to know the answer to that same question in the early 70's, so I
built a subdivided gap system with 24 electrodes each adjustable and
arranged in rows of 4 so I could jumper them to come up with a wide range
of combinations.  It seems most NST systems running 30 ma seemed to favor
either 2 or 3 max for good performance.  With 60 and 120 ma driving current
the favorite was 5-6 gaps (60 ma) and 7-9 gaps (120 ma).  This system was
tried with 5 different NST powered coils and produced similar results. 
Coil sizes varied with diameters from 3 in thru 18 inch in a 4:5 to 1
aspect ratio for most (one was 6:1).  Multibladed rotors are not necessary
and usually overquench as someone in the List recently posted.  The very
best system for small coils is still the synchro RSG running at 1800 RPM
with a 4 electrode rotor.  We use 2 stationary gaps on each side of the
wheel for a series of 4 total gaps usually set to 1/16th inch each gap. 
This produces a very smooth output which fires early on the variac and
delivers consistently good quenching for NST powered systems.  The synchro
RSG works good with both 60 and 120 ma drives at either 12 kV or 15kV.  The
subdivided stationary gaps I described above usually work best with a
150-200 CFM blower fan arranged at 1 1/2-2 inches away from the active
sparking area.  The vacuum cleaner suction system also works very well to
promote good gap quench but it's usually not necessary unless you drive
above 120 ma.  

----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Results of new single static gap
> Date: Saturday, August 29, 1998 11:23 AM
> 
> Original Poster: Richard Hull <rhull-at-richmond.infi-dot-net> 
> 
> 
> 
> Tesla List wrote:
> 
> > From: "Thornton, Russ #CSR2000" <ThorntoR-at-rc.pafb.af.mil>
> >
> > > Tesla List wrote:
> > >
> > > > ----------
> > > > From:  Thornton, Russ #CSR2000 [SMTP:ThorntoR-at-rc.pafb.af.mil]
> > > > Sent:  Monday, August 24, 1998 6:06 AM
> > > > To:  'Tesla discussion Group'
> > > > Subject:  RE: Results of new single static gap
> > > >
> > > > All,
> > > > This brings up a question that has been rattling around in my head
for a
> > > > while now. Actually two questions.
> > > >
> > > > 1)  How are the static gap distances arrived at and why do
you(generic)
> > > > divide them up the way you do?
> > >
> > > ..........................They are normally arrived at through
serendipity
> > > and
> > > guesstimate, tempered by the effort needed to create large numbers of
well
> > > aligned static gaps and the realization that the distance between
gaps
> > > will
> > > become vanishingly small in high numbered systems with attendant
fouling
> > > and
> > > maintenance nightmares.  The proper distances are arrived at totally
> > > through
> > > good ole trial and error (rank beginner) or educated and calibrated
> > > eyeball
> > > (old
> > > hand).  R. Hull
> > > ..........................
> > >
> > Here is another slant on my question.  Has anyone come up with any kind
of a
> > quantitative or qualitative relationship between the difference
between(for
> > example) ten 0.01 gaps and five 0.02 gaps?
> >
> > Russ Thornton
> > CSR 2040,
> > Building 989, Rm.  A1-N20
> > Phone: (407) 494-6430
> > Email: thorntor-at-rc.pafb.af.mil
> 
>   Russ,
> 
> The distance adjustment differential is totally non-linear and
frighteningly
> near geometric in that the more gaps bust the arc up so bad that micro
> distancing is demanded even with 15KV inputs over 12 gaps.  Thus, only
> elemental
> tungsten can play the game up in these high gap numbers.  (due to near
zero
> fouling).
> 
> Again, your firing point demands on the sine will critically affect
spacing,
> too.  There is not rule other than chaos.
> 
> Richard Hull, TCBOR
>