If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
Most everyone has seen photos of straight "sword-like" Tesla coil arcs with superimposed "spiral" features. The majority of the of the photos that I have seen were of discharges created by VTTCs, but they have also been noted on SSTCs.
There have been several theories proposed to explain the spiral features, but I don't know that there has been a universally-accepted answer.
While researching high-speed photography, I came across some images of exploding balloons filled with hydrogen/oxygen gas mixtures. The ignition of the compressed gas mixture produced the expected bright fireball, but what was unusual was the presence of straight, spiriform streamers extending out from the center of the fireball. These are remarkably similar to the spiraform streamers seen in some Tesla coil discharges.
I have no new insight into how Tesla coils generate spiraform streamers, and I have no idea if there is any commom physical phenomenon behind Tesla coil streamers and the streamers generated by the hydrogen/oxygen explosions, but the similarity in appearance is amazing.
See the negative image in the second column, third from the top:
I'd be interested to hear of anyone's explanation for this ......
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
My guess is that the spiral streaks are just the trails of solid ejecta (such as latex balloon fragments). A few of the flying bits are spinning or tumbling.
[edit] Balloon fragments might get a lot of non-radial momentum from their own elastic contraction.
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
Yes, I go with the fragments theory regarding the balloons too.
With regard to streamers, I have observed this too, and the spirals are quite tight an regular. My guess is that the magnetic field of the TC is twisting the plasma in the streamer as it grows.
Registered Member #2372
Joined:
Location:
Posts: 62
There is a generic plasma instability called the m=1 or "kink mode" in which a straight current carrying wire or plasma column will tend to make a spiral shape. This could be the cause of the spiral features in the tesla coil streamers you speak of. Knowing the current etc. one should in principle be able to run through the math and determine if this is in fact the cause.
Much in the same way that two parallel current carrying wires are attracted to one another or antiparallel wires push away from one another any current carrying system will act to increase its inductance.
Registered Member #2372
Joined:
Location:
Posts: 62
The Z pinch doesnt cause a spiral shape. The main instabilities for a current carrying channel are the M=0 sausage mode and the M=1 kink mode. The Zpinch just leads to the channel being compressed on axis (JxB force, or directly from the Lorentz force), during this compression process the m=0 or m=1 modes can be excited.
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
The spiral streamers have always fascinated me too, and over the last few years I haven't seen a definite explanation for them. Very similar formations can be seen on VTTCs and on SSTCs which have a halfwave input, however the VTTCs always seem to produce the most impressive effect (as they are usually halfwave too). The effect appears to be definitely down to the shape of the RF envelope coming out the top, and for some reason half sine waves produce long swords..!
After working in a company which design and produce high power inverter products of various frequencies and outputs for the last couple of years, I have always meant to try bizarre shaped waveforms at different frequencies (just software changes in the inverter) and see what happens to the spark appearance! What kind of swords would come out the top if the AC waveform has some 3rd harmonic? If people are interested, I might hurry up and post some results one day
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Avalanche wrote ...
After working in a company which design and produce high power inverter products of various frequencies and outputs for the last couple of years, I have always meant to try bizarre shaped waveforms at different frequencies (just software changes in the inverter) and see what happens to the spark appearance! What kind of swords would come out the top if the AC waveform has some 3rd harmonic? If people are interested, I might hurry up and post some results one day
I've been having this same idea in the back of my mind for a long time, and I am sure you would get some very interesting results. I did some primitive experiments that seemed to show that a faster rise of the RF envelope produced more VTTC-like sparks than with just standard half-wave rectified mains. This is certainly only valid up until a certain point of course, as interrupted SSTCs, with a very very fast rise don't make very swordlike sparks at all.
If you have the possibility to try this out, I would be very interested in seeing some results.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hello guys,
dugg wrote ...
There is a generic plasma instability called the m=1 or "kink mode" in which a straight current carrying wire or plasma column will tend to make a spiral shape. This could be the cause of the spiral features in the tesla coil streamers you speak of. Knowing the current etc. one should in principle be able to run through the math and determine if this is in fact the cause.
Much in the same way that two parallel current carrying wires are attracted to one another or antiparallel wires push away from one another any current carrying system will act to increase its inductance.
This is turning genuinely fascinating for me - could you please elaborate it a bit? Are you saying that a current-caryying plasma channel tends to increase it's inductance by twisting itself into a coil? :O
Z pinch is rather simple to visualize, but twisting effect on tesla coil streamers isn't. It also only seems to be happening with low current, long duration streamers and not on short-lived high energy streamers of disruptive TC's, what is the reason for that?
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Spiraform TC streamers & hydrogen/oxygen explosions
