Re: Magnetization of Toroid

>Message-ID: <199608040425.WAA10682-at-poodle.pupman-dot-com>
>Date: Sat, 3 Aug 1996 22:25:04 -0600
>From: Tesla List <tesla-at-poodle.pupman-dot-com>
>To: Tesla-list-subscribers-at-poodle.pupman-dot-com
>Subject: Re: Magnetization of Toroid

>Date: Sat, 3 Aug 1996 06:42:13 -0700
>From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
>To: tesla-at-pupman-dot-com


>This is all true for a nonmagnetized piece of ferromagnetic material 
>and a compass.  However, an oriented magnetic field seems to be 
>imparted to the toroid by the TC discharge.  It can be "mapped" by 
>moving a compass around the outer diameter of the toroid.  Also, 
>placing and centering the compass in the the center of the toroid 
>definitely aligns it to the magnetic field imparted to the toroid.  The 
>field in the toroid has two magnetic poles by this method.  The 
>interesting part is that the orientation of this field can be changed 
>somewhat by firing the coil with the toroid in a different position in 
>reference to the coil.
>Questions are.  Does a TC RF field impart an oriented field magnetic 
>field on a ferromagnetic toroid?  Would a DC TC discharge impart an 
>oriented field magnetic field on a ferromagnetic toroid?  Do 
>surrounding environmental EM fields influence TC discharges?

   This is interesting.

   A magnetic material placed into a magnetic field (the earth's) will
   eventually become magnetized in the direction of the ambient field.
   This process can be hurried along by disturbing the molecules with
   heat or shock.  This shock can be physical or magnetic or perhaps
   electric.  I think the toroid sees all 3 of these during operation.

   How does the orientation of the induced field in the toroid compare
   with the earth's field?  Can you control at will the orientation of
   the toroid's resultant remanence field?  How does one explain the
   effect of 'firing the coil with the toroid in a different position
   in reference to the coil' ?  Is there anything else about the
   operation of the TC that affects the orientation of the toroid's
   remanence field?  And what exactly do you mean about 'a different
   position in reference to the coil' ?  Thanks.

   Another question might be about the actual time profile of the
   magnetic field in the vicintiy of the toroid.  It sees some field
   from the primary and from the current flowing in the secondary.
   Breakdown (loss of charge) to the air is easier when the toroid is
   negative, so the secondary current's time profile would be a little
   different on the negative half of the cycle than the positive half. 
   This different current profile should distort the magnetic field
   around the top of the secondary.  Due to hysteresis effects
   materials are more likely to pick up the more significant of the
   peaks in the magnetic field, resulting in a net DC field from and
   AC field.  Does anybody have a measurement of the magnetic field
   *waveshape* in the vicinity of the toroid?  It could be significant.


   Incidentally, only a little mention of ambient magnetic fields was
   present in the articles about the separation of ions from the
   plasma around the toroid during operation.  The electrons are more
   deflected by a magnetic field than the ions are (remember the old
   ion traps on TV CRT's?) .  Thus I would expect some spatial
   separation of the electrons and the ions by this process alone.

   Being thousands of times lighter, the electrons are very fast
   compared to the ions.  We have this problem in some of our
   secondary-emission chambers in our primary proton beamline here. 
   The proton beam passes through the monitors and produces a shower
   of secondary electrons from the plates inside.  If the beampipe
   vacuum is poor the beam also produces positive gas ions.  The
   balance of charges collected by the collecting plates is affected
   by the timing of the beam pulses.  Whereas the steady-state flow of
   positive ions and (negative) electrons to the collecting plates
   results in such-and-such a current (which we measure in the control
   room and which is proportional to beam), a fast interruption in the
   beam current results in the loss of electrons first and so there is
   quite a momentary disturbance in the calibration of the
   secondary-emission chambers.  An opposite effect happens when we
   turn the beam on.  Needless to say, these monitors work a lot
   better in a good vacuum where there are very few gas ions to change
   the calibration.  Considering the mobility of the ions as compared
   to the electrons, and considering that the TC is s pulsed device, I
   imagine that this effect, combined with deflection by ambient
   magnetic fields, is resulting in DC charge being picked up by an
   electrometer placed a good distance away from the toroid.

 Fred W. Bach ,    Operations Group        | Internet: music-at-triumf.ca
 TRIUMF (TRI-University Meson Facility)    | Voice:  604-222-1047 loc 6327/7333
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 University of British Columbia, Vancouver, B.C., CANADA   V6T 2A3
 "Accuracy is important. Details can mean the difference between life & death."
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