PSN-L Email List Message

Subject: Re: diamagnetic levitation seismometer possibility
From: Charles R Patton charles.r.patton@........
Date: Tue, 10 Jul 2012 20:48:57 -0700


Well, one way to get around this problem would be to use an AC current 
to modulate the permanent magnets by an amount bigger than the 
valley/crest amplitude.
Chas.

On 7/10/2012 8:24 PM, meredith lamb wrote:
> Charles and all,
>
> PG comes in a range of impurity levels.  The "worst" seems to
> range roughly up to ~ 30 parts per million.  The average use PG
> seems to vary roughly around 12 to 9 parts per million; I suspect this
> is the usual material ~ we, use or commonly obtain.  Lab grade
> PG may range around 6 to 8 ppm.  Some "super" pure PG
> (usually used in government nuclear instrumentation), may have
> around 1 to 3 parts per million.  These are my "memory"
> estimates...which could be off now....or, manufacturing process's
> could have improved since.
>
> Years back I built a levitation device that consisted of a large
> ring neodymium magnet, and ~ forced a smaller neodymium
> magnet in the center (opposing fields).  This was a replica
> of one David Lamb built.  With, the right size of round or
> even square PG (that levitates); one can approximate the
> locations of impurities, simply by bringing a much smaller
> magnet near the levitating PG.  The PG will rotate and
> settle closest to the small hand held magnet where the
> magnetic impurity exists, and/or for various ~ spots therein.
> All this demonstrates is the existence of the Minuit impurity's and
> in itself it's preference for the PG seeking, say, the greatest
> magnetic field at those locations.
>
> In my experience, with any given horizontal (directional)
> magnet setup and using, say, a 5/8" square of PG; the
> PG will "prefer" ~ several locations along it's path.  With
> a gentle slow finger push, the PG will speed up, slow down
> as it crosses these (~ broad) area magnetic peaks and valleys.
> In other words one can adjust the leveling for whatever location
> works best or is more convenient, or, stable, or smoother
> for operation.  One could, ascribe such erratic movement
> to variations in the magnetic fields and/or impurities in
> the PG, or other (?) possibilities.  Yes; the faster the PG
> moves, the less obvious these peaks and valleys are seen.
>
> Meredith
>
> On Tue, Jul 10, 2012 at 6:40 PM, Charles R Patton 
> > wrote:
>
>     On 7/10/2012 7:50 AM, Thomas Dick wrote:
>>     On 7/10/2012 7:51 AM, chrisatupw@.......
>>      wrote:
>>>     From: Charles R Patton charles.r.patton@........
>>>     
>>>     Subject: Re: diamagnetic levitation seismometer possibility
>>>     Interesting observations about the possibility of diamagnetic
>>>     roughness. This brings up two observations:
>>>     1) By the current theories of magnetic flux lines as I
>>>     understand them, there is no possibility for them to exhibit
>>>     "kinks or roughness" at the scales and method of field
>>>     generation we're discussing.
>>>     Hi Charles,
>>>     That is correct as I understand it. Flux lines in free space are
>>>     often curved, but never kinky!
>>>
>>>     2) So that leaves two possibilities in my mind:
>>>         a) The magnetic field is undergoing slight changes in field
>>>     strength with the actual counterpressure of the carbon being
>>>     levitated. Hard to imagine with the relative strengths of the
>>>     permanent magnets -- but still a possibility.
>>>     There is no reason to suppose that the tiny reaction is in any
>>>     way 'rough' or inelastic.
>>>
>>>         b) The carbon diamagnetic properties exhibit a domain
>>>     phenomenon in a similar vein to the ferromagnetic properties of
>>>     iron.
>>>     The diamagnetic materials don't form domains. The domains in
>>>     some ferrous materials are a property of the close coupled
>>>     interaction in that particular crystal stucture between the iron
>>>     atoms. But you DO get alloys containing a high proportion of
>>>     iron which are NOT ferro-magnetic !! eg the Austenitic Stainless
>>>     Steels.
>>>     While the field strength at the magnet's surface is likely to
>>>     vary along the length, the levitation is maybe 1/2 to 1 mm, but
>>>     small quakes are measured in 10s of nano metres, maybe 1/10,000
>>>     of this.
>>>     In a more blue sky way of reasoning, project the following thoughts:
>>>     1) Dr. Randall Peters has brought to this list the interesting
>>>     concepts of mesoscale damping. Part of what I take away from
>>>     that concept is that as we burrow down in dimension, the concept
>>>     of an amorphous solid with smooth mathematically described
>>>     properties breaks down. Just as ferrous magnetics were thought
>>>     to be smooth, the discovery of Barkhausen noise was discovered
>>>     early on to be the individual magnetic domains switching.
>>>     Diamagnetic  properties come from electron properties of masses
>>>     of atoms just as the ferrous magnetic properties do.  So, atoms
>>>     can move within a "solid".  The most stable solids are
>>>     crystalline in nature, where the atoms are locked in both space
>>>     and orientation.    The big question, "Would a crystalline
>>>     diamagnetic solid exhibit this magnetIc "roughness", perhaps
>>>     equivalent to the Barkhausen noise? The experiment to perform
>>>     here is to use a Barkhausen test setup, but substitute carbon
>>>     for iron.
>>>
>>>     Charles R. Patton
>>>
>>>     On 7/9/2012 9:34 AM, chrisatupw@.......
>>>      wrote:
>>>     From: Bob McClure bobmcclure90@.........
>>>     
>>>     Sent: Mon, 9 Jul 2012 15:02
>>>     Subject: Re: diamagnetic levitation seismometer possibility
>>>>     I, too, have carried out diamagnetic levitation experiments
>>>>     similar to those by Meredith Lamb. Although the large amplitude
>>>>     motion looks smooth and frictionless, what I concluded for very
>>>>     small amplitudes, such is not the case. The supporting magnetic
>>>>     field has small-scale roughness, and the levitated graphite
>>>>     tends to hung up in the hills and valleys of the resulting force.
>>>>
>>>>     I don't understand this. I would only expect 'field roughness'
>>>>     to show up for linear motions comparable to the levitation
>>>>     height, of 1/2 to 1 mm, NOT for tiny movements of ~100 nano
>>>>     metres.
>>>>     One problem that I had with levitating graphite was due to it's
>>>>     propensity to pick up lint, hairs and dust. These can and do
>>>>     effect a very light slider. Another problem is the extremely
>>>>     high field gradients at the edges of the magnets picks up
>>>>     magnetic and paramagnetic dust only too easily. I clean magnets
>>>>     using a roll of PVC tape - you stick it onto the surface and
>>>>     then peel it of with the rubbish attached.
>>>>     Regards,
>>>>     Chris Chapman
>>>
>>>
>>     Chris & all ...
>>
>>     All of you seem locked in on the material being the problem ...
>>     and you may be correct. But what if, the "change" you are
>>     "seeing" and blaming on the field roughness is being induced by 
>>     earth's magnetic field or from other radiations from space. I
>>     suggest shielding could be an issue. Some of you might remember a
>>     seismic unit I created years ago using a large horseshoe shaped
>>     magnet dampened with oil. That setup was affected by the 200 watt
>>     10 meter amateur radio repeater I was operating at the time.
>>
>     After more thought, there is a material related "roughness"  that
>     comes to mind.  For a moment follow me with a thought experiment. 
>     You have a stick that smoothly alternates in diameter along it
>     length and whose density is less than that of water.  You push the
>     stick lengthwise into the water while plotting the pressure it
>     takes. This  plot will show a pressure variation due to the
>     diameter variation.  This immersion is very similar to the carbon
>     in a magnetic field.  We know that the preparation method is
>     important to making diamagnetic carbon,  and therefore I don't
>     think it's a great leap of imagination to believe that is not
>     entirely diamagnetically uniform at the macroscopic level.    Now
>     for the leap in this analogue.   Back to the stick.  Instead of a
>     smoothly varying profile, imagine a sawtooth, perhaps even a bit
>     re-entrant.  As it is pushed in the water the pressure required
>     will have steps -- the "roughness" characteristic.  Furthermore if
>     the ridges form actual water holding ridges (like a water fountain
>     made from bowls) then this will even have a hysteresis
>     characteristic.  I  argue that inclusions of low or
>     non-diamagnetic particles/portions in the carbon will lead to a
>     roughness of the levitating force as the carbon moves up and down
>     in the levitating field.
>     Regards,
>     Charles R. Patton
>
>



  
    
  
  
    
Well, one way to get around this problem would be to use an AC current to modulate the permanent magnets by an amount bigger than the valley/crest amplitude. 
Chas.

On 7/10/2012 8:24 PM, meredith lamb wrote:
Charles and all,

PG comes in a range of impurity levels.  The "worst" seems to
range roughly up to ~ 30 parts per million.  The average use PG
seems to vary roughly around 12 to 9 parts per million; I suspect this
is the usual material ~ we, use or commonly obtain.  Lab grade
PG may range around 6 to 8 ppm.  Some "super" pure PG
(usually used in government nuclear instrumentation), may have
around 1 to 3 parts per million.  These are my "memory"
estimates...which could be off now....or, manufacturing process's
could have improved since.

Years back I built a levitation device that consisted of a large
ring neodymium magnet, and ~ forced a smaller neodymium
magnet in the center (opposing fields).  This was a replica
of one David Lamb built.  With, the right size of round or 
even square PG (that levitates); one can approximate the
locations of impurities, simply by bringing a much smaller
magnet near the levitating PG.  The PG will rotate and
settle closest to the small hand held magnet where the
magnetic impurity exists, and/or for various ~ spots therein.
All this demonstrates is the existence of the Minuit impurity's and
in itself it's preference for the PG seeking, say, the greatest
magnetic field at those locations.  

In my experience, with any given horizontal (directional)
magnet setup and using, say, a 5/8" square of PG; the
PG will "prefer" ~ several locations along it's path.  With
a gentle slow finger push, the PG will speed up, slow down
as it crosses these (~ broad) area magnetic peaks and valleys.
In other words one can adjust the leveling for whatever location
works best or is more convenient, or, stable, or smoother
for operation.  One could, ascribe such erratic movement
to variations in the magnetic fields and/or impurities in
the PG, or other (?) possibilities.  Yes; the faster the PG
moves, the less obvious these peaks and valleys are seen.

Meredith
 

On Tue, Jul 10, 2012 at 6:40 PM, Charles R Patton <charles.r.patton@........> wrote:
On 7/10/2012 7:50 AM, Thomas Dick wrote:
On 7/10/2012 7:51 AM, chrisatupw@....... wrote:
From: Charles R Patton charles.r.patton@........
Subject: Re: diamagnetic levitation seismometer possibility
Interesting observations about the possibility of diamagnetic roughness.  This brings up two observations:
1) By the current theories of magnetic flux lines as I understand them, there is no possibility for them to exhibit "kinks or roughness" at the scales and method of field generation we're discussing. 
Hi Charles,
 
    That is correct as I understand it. Flux lines in free space are often curved, but never kinky!

2) So that leaves two possibilities in my mind:
    a) The magnetic field is undergoing slight changes in field strength with the actual counterpressure of the carbon being levitated.  Hard to imagine with the relative strengths of the permanent magnets -- but still a possibility. 
 
    There is no reason to suppose that the tiny reaction is in any way 'rough' or inelastic.

    b) The carbon diamagnetic properties exhibit a domain phenomenon in a similar vein to the ferromagnetic properties of iron. 
    The diamagnetic materials don't form domains. The domains in some ferrous materials are a property of the close coupled interaction in that particular crystal stucture between the iron atoms. But you DO get alloys containing a high proportion of iron which are NOT ferro-magnetic !! eg the Austenitic Stainless Steels.  
    While the field strength at the magnet's surface is likely to vary along the length, the levitation is maybe 1/2 to 1 mm, but small quakes are measured in 10s of nano metres, maybe 1/10,000 of this.
In a more blue sky way of reasoning, project the following thoughts:
1) Dr. Randall Peters has brought to this list the interesting concepts of mesoscale damping.  Part of what I take away from that concept is that as we burrow down in dimension, the concept of an amorphous solid with smooth mathematically described properties breaks down.  Just as ferrous magnetics were thought to be smooth, the discovery of Barkhausen noise was discovered early on to be the individual magnetic domains switching.  Diamagnetic  properties come from electron properties of masses of atoms just as the ferrous magnetic properties do.  So, atoms can move within a "solid".  The most stable solids are crystalline in nature, where the atoms are locked in both space and orientation.    The big question, "Would a crystalline diamagnetic solid exhibit this magnetIc "roughness", perhaps equivalent to the Barkhausen noise?    The experiment to perform here is to use a Barkhausen test setup, but substitute carbon for iron.     

Charles R. Patton
 
On 7/9/2012 9:34 AM, chrisatupw@....... wrote:
From: Bob McClure bobmcclure90@.........
Sent: Mon, 9 Jul 2012 15:02
Subject: Re: diamagnetic levitation seismometer possibility
I, too, have carried out diamagnetic levitation experiments similar to those by Meredith Lamb. Although the large amplitude motion looks smooth and frictionless, what I concluded for very small amplitudes, such is not the case. The supporting magnetic field has small-scale roughness, and the levitated graphite tends to hung up in the hills and valleys of the resulting force.

I don't understand this. I would only expect 'field roughness' to show up for linear motions comparable to the levitation height, of 1/2 to 1 mm, NOT for tiny movements of ~100 nano metres.
    One problem that I had with levitating graphite was due to it's propensity to pick up lint, hairs and dust. These can and do effect a very light slider. Another problem is the extremely high field gradients at the edges of the magnets picks up magnetic and paramagnetic dust only too easily. I clean magnets using a roll of PVC tape - you stick it onto the surface and then peel it of with the rubbish attached.
 
    Regards,
 
    Chris Chapman
 
 


Chris & all ...

All of you seem locked in on the material being the problem ... and you may be correct. But what if,  the "change" you are "seeing" and blaming on the field roughness is being induced by  earth's magnetic field or from other radiations from space. I suggest shielding could be an issue. Some of you might remember a seismic unit I created years ago using a large horseshoe shaped magnet dampened with oil. That setup was affected by the 200 watt 10 meter amateur radio repeater I was operating at the time.

After more thought, there is a material related "roughness"  that comes to mind.  For a moment follow me with a thought experiment.  You have a stick that smoothly alternates in diameter along it length and whose density is less than that of water.  You push the stick lengthwise into the water while plotting the pressure it takes.  This  plot will show a pressure variation due to the diameter variation.  This immersion is very similar to the carbon in a magnetic field.  We know that the preparation method is important to making diamagnetic carbon,  and therefore I don't think it's a great leap of imagination to believe that is not entirely diamagnetically uniform at the macroscopic level.    Now for the leap in this analogue.   Back to the stick.  Instead of a smoothly varying profile, imagine a sawtooth, perhaps even a bit re-entrant.  As it is pushed in the water the pressure required will have steps -- the "roughness" characteristic.  Furthermore if the ridges form actual water holding ridges (like a water fountain made from bowls) then this will even have a hysteresis characteristic.  I  argue that inclusions of low or non-diamagnetic particles/portions in the carbon will lead to a roughness of the levitating force as the carbon moves up and down in the levitating field. 
Regards,
Charles R. Patton




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