RE: Longitudinal Waves

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

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

Hi Peter,

>Many of us have direct experience that radios and RC car/plane transmitters
do work when the receiver is in the perpendicular plane of the rod antenna
of the transmitter, and that the receiver does not work when the antenna is
pointing directly at it (many RC model planes have been lost this way!

You're making a good effort.  Technically, yes, the energy radiating
directly in line with the antenna is longitudinal.  But the transceiver was
designed to completely ignore this part of the wave, so that is a design
characteristic of the radio and not a characteristic of longitudinal waves.

To really understand longitudinal waves we need to look first at the basic
unit of all waves, the pulse.  The radio transmissions from your transmitter
are wave constructs.  That is, they are formed from several consecutive
pulses.  In a transmitter, the longitudinal component of the pulses is
completely ignored.  Only the first second of each pulse is registered in a
sine wave.  So by the time the pulse has damped to a longitudinal wave, the
transmitter has no interest in it.

I have just finished posting my journal entries online for my most recent
longitudinal wave experiments.  It is graphic intensive, so if you have a
slow connection you'll want to do something else for a few minutes while the
pictures load.  I split the journal entries into two pages...
http://www.tesla-coil-builder-dot-com/FlatSpiralSecondaryLongitudinal.htm
http://www.tesla-coil-builder-dot-com/FlatSpiralSecondaryPlasmaBall01.htm

Dave

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, February 12, 2002 9:32 PM
To: tesla-at-pupman-dot-com
Subject: RE: Longitudinal Waves


Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Peter.Lawrence-at-Sun-dot-com>

Dave,
     I can't claim to know what you mean by longitudinal waves, but I've got
a hunch, so lets see...

Many of use are familiar with walkie-talkie radios, and maybe also radio
controlled car/plane transmitters - the ones I'm talking about have straight
rod antennas.

I'm sort of guessing that you are using the term transverse wave to describe
the emissions that extend outward perpendicular to the rod antenna, and
longitudinal wave to describe the emissions that extend outward directly
in the direction the antenna is pointing.

Many of us have direct experience that radios and RC car/plane transmitters
do work when the receiver is in the perpendicular plane of the rod antenna
of the transmitter, and that the receiver does not work when the antenna is
pointing directly at it (many RC model planes have been lost this way!).

Many of us on this list concure with what our experience tells us and what
physics books tell us which is that there is energy transfer in transverse
waves (electromagnetic radiation), but that there is no energy transfer
in the longitudinal direction. This is why many of us are wondering how
a TC (which is transfering energy from a primary LC to a secondary LC) can
work with longitudinal waves since sparks require lots of energy.

Peter Lawrence.






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>Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dave-at-volantis-dot-org>
>
>Hi Malcolm,
>
>>Maybe we are not talking about the same thing. I can induce ringing in a
>typical TC resonator and watch it ring down. I can vary ringdown times from
>>10mS if the Q of the circuit is high enough to as short as I want by
>increasing its resistive losses. I don't need longitudinal waves to explain
>that result do I?
>
>The ring down envelope has nothing to do with the longitudinal wave.  It is
>still a part of the voltage.  The longitudinal wave is not electromotive
>force.  In fact, I keep coming down to the idea that longitudinal waves are
>electrostatic force.
>
>It seems to me that the very first moment of the pulse is electrostatic,
>then there is the damped wave that is electromotive, and then the wave
>returns to electrostatic after the electromotive force has damped out.
>Perhaps the electrostatic nature of the wave is always there, but the
>electromotive force overwhelms the electrostatic during its short life
span?
>
>Tonight I hooked up my wye coil.  It's three parallel wires wound in a flat
>spiral secondary and all three leads are joined at the terminal.  I decided
>to operate the coil with no secondary ground and with the terminal
connected
>to an electrostatically sealed 30" diameter flat aluminum disk.  I have a
>1/4" layer of Plexiglas plus 1/4" of hot glue separating the primary and
>secondary, and even with this nearly 500,000 volts of dielectric, I was
>still getting an arc between primary and secondary.  This, and no sparks at
>the terminal.  My thought is that I have succeeded in generating an
>electrostatic (longitudinal) wave of high pressure.
>
>Indeed, the plasma globe shows concentric spheres of light as though
>spherical standing waves separated the layers.  The color was an eerie
>green.
>
>The way standard solenoid coils are wound and configured, the object is to
>increase the resonant rise of the voltage.  This is what causes the long
>sparks.  Voltage tends to be near the terminal and current tends to be near
>the ground wire.
>
>Flat spiral coils do not break out sparks easily unless an object is
brought
>near the terminal, such as the outer lead or a hand held fluorescent tube.
>This is probably due to voltage being mostly between the outer windings,
>which is near where the ground wire would normally be.  The terminal is
>highly positively charged.  But this is where the research needs to be
done.
>It is tempting to call the strong electrostatic charge a high voltage, but
>it doesn't behave like a solenoid voltage peak.  It behaves like a
>longitudinal wave.
>
>If I remove my 30" electrostatically sealed disk from the terminal and
>connect a standard copper ball, the charge of the ball is leaked into the
>air and there is no arcing between the primary and secondary.  If the high
>pressure being exerted against the terminal were voltage oscillations,
there
>would be long streamers breaking out.  But there are none.  If the high
>pressure were longitudinal waves, then the charge would be overstuffed into
>the flat disk causing a pressure in the disk with back pressure on the
>terminal and thus higher pressures within the secondary.  And this is what
>appears to be evident due to arcing through 500,000 volts of dielectric.
>
>It's getting late.  I'll give this some more thought and measurement
>tomorrow.
>
>Dave
>
>
>