Re: VERY HIGH BPS at 6kw!

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

Original poster: "tesla by way of Terry Fritz <teslalist-at-qwest-dot-net>" <tesla-at-paradise-dot-net.nz>

Team
I've run a very similar coil system (but Cp was 90nF)
Got similar ARC lenghts too
With a ASRSG capable of high bps I noted that the arcs would tend to be
vertical at high BPS.

The attachment point to the toroid could be selected by the speed of the
ASRSG.

I do not believe that the near vertical arcs were the result of the heating
effect proposed by Malcolm and sometimes mentioned by others on the list.
I have the theory that at high bps the PRF is more affected by WHERE the
effective toroid capacitance is coming from.

The effective toroid capacitance is mostly downwards to the ground. This
means that the arcs will tend vertical due to the fact that there is a field
SHUNTING effect towards the ground due to the high bang rate. The arcs will
go in the direction away from the capacitance of ground and this is more
pronounced when the PRF is higher.

Any other opinions
Rgds
Ted L in NZ
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, May 09, 2003 4:14 PM
Subject: Re: VERY HIGH BPS at 6kw!


 > Original poster: "Malcolm Watts by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
 >
 > Hi Steve,
 >
 > On 8 May 2003, at 21:46, Tesla list wrote:
 >
 >  > Original poster: "Steven Ward by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>
 >  >
 >  > Hi all,
 >  >
 >  > I built a 4 pack MOT supply and it works ok.  There is no limiting
besides
 >  > the wires that come from the 240V outlet.  But thats not so
 >  > important.  This coil is running with a static sucker gap, and only
about
 >  > .0475uf of capacitance.  In this scenario, the arcs SCREAM!  It sounds
like
 >  > 1000bps or maybe more!  The sparks are WHITE and hot when the arc to
the
 >  > ground.  But, the coil is dissapointing with only 6-6.5 feet of
 >  > spark.  Also, the sparks will start downward, and end up vertical in
the
 >  > air!  This is common for high BPS i guess.
 >
 > It is common where there is effectively continuous heating of the air
 > channel.
 >
 >    But, i want about 9 feet or
 >  > more, so i need to lower the bps.  So, im thinking of making the cap in
the
 >  > .09 to .1uf range!  I know, this is HUGE.
 >
 > I wouldn't regard it as such. I've happily used caps of that size in
 > the past.
 >
 >    Right now, im using 13 turns on
 >  > the primary (7"ID  23"OD
 >  > .25" cu) with a 6.5"x36" 24awg secondary and a 4.5"x30" toroid.  I know
 >  > that with that huge cap, i will only use a small fraction of those
primary
 >  > turns.  But, just how BAD is this scenario?  Im basically limited to
9kv or
 >  > so.  I do plan to eventaully (if a 5 turn primary works good for
example)
 >  > make the primary from .5" copper or something bigger.  How bad will the
 >  > caps be stressed?  I have 3 strings of the geek type MMC caps, maybe 4
or 5
 >  > with the larger cap values (those nearing .1uf).  Are there any coils
 >  > similar to mine out there?  IF so, what is the typical output?  Id like
10
 >  > feet if possible.
 >
 > It is *not* the number of turns that count (how many times have I
 > said this before??) - it is the *inductance* that matters and if you
 > are concerned about very high primary currents and consequent gap
 > losses, then build a much lower frequency coil to get Xp (Lp) up. I
 > think your biggest problem is going to be a voltage limitation with
 > your relatively short secondary as Ep climbs.
 >
 > Malcolm
 >
 >
 >