PSN-L Email List Message
Subject: Re: diamagnetic levitation seismometer possibility
From: chrisatupw@.......
Date: Wed, 11 Jul 2012 04:27:10 -0400 (EDT)
From: Charles R Patton charles.r.patton@........
Sent: Wed, 11 Jul 2012 1:41
Subject: Re: diamagnetic levitation seismometer possibility
On 7/9/2012 9:34 AM, chrisatupw@....... wr=
ote:=20
From: Bob McClure bobmcclure90@.........
Sent: Mon, 9 Jul 2012 15:02
Subject: Re: diamagnetic levitation =
seismometer possibility
=20
=20
=20
=20
=20
I, too, have carried out diama=
gnetic levitation experiments =
similar to those by Meredith L=
amb. 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 ten=
ds to hung up in the hills and=
valleys of the resulting forc=
e.=20
=20
I don't =
understand this. I would =
only expect 'field =
roughness' to show up =
for linear motions c=
omparable to the levitation =
height, of 1/2 to 1 mm, NOT =
for tiny movements of ~100 =
nano metres.=20
=20
One problem that I had w=
ith 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 e=
asily. I clean magnets using=
a roll of PVC tape - you st=
ick it onto the surface and =
then peel it of with the =
rubbish attached. Chris & al=
l ...
=20
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" an=
d 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 set=
up was affected by the 200 watt 10 meter amateur radio repeater I was =
operating at the time.=20
=20
=20
Chris & all ...
=20
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" an=
d 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 set=
up was affected by the 200 watt 10 meter amateur radio repeater I was =
operating at the time.=20
=20
=20
After more thought, there is a material related "roughness" that co=
mes to mind. For a moment follow me with a thought experiment. You hav=
e 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 ve=
ry similar to the carbon in a magnetic field. We know that the preparat=
ion method is important to making diamagnetic carbon, and therefore I d=
on't think it's a great leap of imagination to believe that is not entir=
ely diamagnetically uniform at the macroscopic level. Now for the =
leap in this analogue. Back to the stick. Instead of a smoothly varyi=
ng profile, imagine a sawtooth, perhaps even a bit re-entrant. As it is=
pushed in the water the pressure required will have steps -- the "rough=
ness" characteristic. Furthermore if the ridges form actual water holdi=
ng ridges (like a water fountain made from bowls) then this will even ha=
ve 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. =20
Regards,
Charles R. Patton
=20
Hi Charles,
=20
I get your point, but two comments :-=20
Pyrolitic graphite is almost increadibly pure carbon. You can peel off =
single atomic layers.=20
And any consideration of roughness the levitating force is immaterial. =
The PG is there to lift the armature and it stays ~put as the armature slid=
es at RIGHT ANGLES to the direction of lift. We have been discussing errors=
/ hangups in this horizontal motion, not in any vertical displacement.=20
Regards,=20
Chris Chapman =20
=20
=20
=20
=20
=20
I, too, have carried out diama=
gnetic levitation experiments =
similar to those by Meredith L=
amb. 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 ten=
ds to hung up in the hills and=
valleys of the resulting forc=
e.=20
=20
I don't =
understand this. I would =
only expect 'field =
roughness' to show up =
for linear motions c=
omparable to the levitation =
height, of 1/2 to 1 mm, NOT =
for tiny movements of ~100 =
nano metres.=20
=20
One problem that I had w=
ith 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 e=
asily. I clean magnets using=
a roll of PVC tape - you st=
ick it onto the surface and =
then peel it of with the =
rubbish attached. Chris & al=
l ...
=20
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" an=
d 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 set=
up was affected by the 200 watt 10 meter amateur radio repeater I was =
operating at the time.=20
=20
=20
Chris & all ...
=20
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" an=
d 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 set=
up was affected by the 200 watt 10 meter amateur radio repeater I was =
operating at the time.=20
=20
=20
After more thought, there is a material related "roughness" that co=
mes to mind. For a moment follow me with a thought experiment. You hav=
e 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 ve=
ry similar to the carbon in a magnetic field. We know that the preparat=
ion method is important to making diamagnetic carbon, and therefore I d=
on't think it's a great leap of imagination to believe that is not entir=
ely diamagnetically uniform at the macroscopic level. Now for the =
leap in this analogue. Back to the stick. Instead of a smoothly varyi=
ng profile, imagine a sawtooth, perhaps even a bit re-entrant. As it is=
pushed in the water the pressure required will have steps -- the "rough=
ness" characteristic. Furthermore if the ridges form actual water holdi=
ng ridges (like a water fountain made from bowls) then this will even ha=
ve 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. =20
Regards,
Charles R. Patton
=20
Hi Charles,
=20
I get your point, but two comments :-=20
Pyrolitic graphite is almost increadibly pure carbon. You can peel off =
single atomic layers.=20
And any consideration of roughness the levitating force is immaterial. =
The PG is there to lift the armature and it stays ~put as the armature slid=
es at RIGHT ANGLES to the direction of lift. We have been discussing errors=
/ hangups in this horizontal motion, not in any vertical displacement.=20
Regards,=20
Chris Chapman =20
=20
=20
=20
=20
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.
=20
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.
=20
One
problem that I had with
levitating graphite was
due to it's propensity
to pick up lint, hairs
and dust. These can an=
d
do effect a very light
slider. Another proble=
m
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. &nbs=
p; 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.&=
nbsp;
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 importan=
t
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.&nbs=
p;
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 arg=
ue 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
=20
Hi Charles,
I get your point, but two comments=
:-
Pyrolitic graphite is almost incre=
adibly pure carbon. You can peel off single atomic layers.
And any consideration of roughness=
the levitating force is immaterial. The PG is there to lift the armature a=
nd it stays ~put as the armature slides at RIGHT ANGLES to the direction of=
lift. We have been discussing errors / hangups in this horizontal motion, =
not in any vertical displacement.
Regards,
Chris Chapman &n=
bsp;
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