Magneto-Science
Magnetic field effects on dia- and paramagnetic (“non-magnetic”)substances.
Moses effect(growth of cucumber)
Magneto-Archimedes levitation
Vaporization under magnetic field
Magnetic wind tunnel
Magnetic dipole interaction
Magntohydrodynamic motor
Koichi Kitazawa
Introduction
Energy
Force
 2
E
B
20
Fmagnetic
 B

B
 0 z
 ; Magnetic susceptibility [-] ,
0 ; Permeability of vacuum [4p×10-7 A/m],
B ; Magnetic flux density [T]
Diamagnetic material
Repelled from
magnetic field
Paramagnetic material
Attracted from
magnetic field
Magnetic energy is very small comparing
with the energy of room temperature RT.
Electric, permanent
magnet
B ～1 T
Higher field
B ～10 T 10 times
Force
100 times! (∝B 2)
Cryo-cooler cooled magnet
Maximum field：10 T
Room temperature bore : f 100 mm
2
B∂B /∂ z (T /m)
B (T)
10
8
6
4
2
0
400
200
0
-200
-400
-300 -200 -100
0 100 200 300
z (mm)
Fig. Distributions of magnetic field B and
the index of magnetic force B∂B/∂z
Sumitomo Heavy Industries, Ltd.
Liquid Helium free
The Moses Effect & the Reversed Moses Effect
Height difference
 2
Dh  
B
20 g 
1
D h=38.9mm
 (water) =－9.031×10-6
B=10T
D h=32.6 mm
 =8.397×10-6
Fig. Photographs of surface profiles of liquid samples water (a)
and CuSO4 aqueous solution (b) in a magnetic field of 10 T.
N. Hirota et al., Jpn. J. Appl. Phys., 34 (1995) L991
Liquid surface profile was changed by strong magnetic field.
Enhanced Moses Effect
By lying two immiscible
liquids
B
Dh  
D 2
B
2 0 g D
1
Making Δ smaller
Fig. Profile of the interface between an organic
solvent (upper) and a copper sulfate aqueous
solution (lower). Bmax =0.56 T
Large interface height difference
by week magnetic fields.
H. Sugawara, et al., J. Appl. Phys. 79 (8), 4721- 4723(1996)
The deformation of interface profile by permanent magnet.
Magnetic Levitation –Diamagnetic Levitation
Fig. Water ball(left) and frog(right)
levitating in the bore of a hybrid magnet.
http://www.sci.kun.nl/hfml/froglev.html
B
B ～1400 T 2 /m
z
The balance of the gravity and magnetic
(repulsive) force
c.f. B(B/z)max.< 500 T2/m
(for ordinary superconducting
magnets)
It is necessary to use a ultrahigh field for diamagnetic levitation.
Magneto-Archimedes Levitation
Considering magnetic buoyant
force from atomsphere
(a)
H2O
=－9.0×10-6
(diamagnetic)
B  0 gD
B

z
D
(b)
Making the susceptibility difference larger
CuSO aq.
4
1 cm
χ=+0.30×10-6
(paramagnetic)
P(O2)=18.2 atm
Fig. Water(a) and paramagnetic CuSO4aq.(b)
levitating in the bore of a s.c. magnet.
Small B∂B/∂z is required.
Paramagnetic substances
can be levitated.
Y. Ikezoe et al., Nature, 393 (1998) 749
Magnetic levitation with usual superconducting magnet
Levitation of paramagnetic substances.
Magnetic Separation
B
B  0 g 1   2   0 gD


z
1   2
D
Stable positions of the substances in
the magnetic field are determined by
Pressure of oxygen gas,
Magnetic field distribution,
Susceptibility of substances,
Density of substances, etc.
Magnetic separation is
possible by utilizing MagnetoArchimedes principle.
Fig. Photographs of separated sugar & salt in
32 atm oxygen gas(upper), and the glasses of
different colors in MnCl2aq.(lower).
Y. Ikezoe et al., Trans. Mater. Res. Soc. Jpn., 25 [1] (2000) 77
Magnetic separation of NaCl & CuSO4
磁場を掃引
Magnetic Wind Tunnel
-6
Paramagnetic oxygen O2=1.80×10
 Air T    O 2 T   12
Susceptibility of air
χAir T  dB
f 
B
μ0
dx
Magnetic force
T；high B
 ；small
f ;small
T
T；low
 ；large
f ;large
Heating
x
flow
heater
Airflow was induced magnetically.
Fig. Creation of magnetic wind
tunnel under 8 T field.
25.0
15.0
4T
2T
10.0
5.0
0T
0
120
240
360
480
T ime,t / min
600
720
Fig. The amount Fig.
of 5oxygen
dissolved
in water
N. Hirota
et al.
at 15℃ in a field at 0 T, 2 T, and 4 T. It is seen
that the rate of dissolution is enhanced
significantly by the magnetic field while the
equilibrium solubility remains the same.
Water surface
O2
O2
O2
O2
O2
O2
O2
O2
O2
Smaller
20.0
Larger
O2 gas
Magnetic susceptibility
Oxygen concentration, C / g m-3
Enhancement of oxygen gas dissolution rate into water
O2
H2O
O2
Smaller
Larger
Magnetic field intensity
v ＞ 1 cm
Fig. The mechanism proposed for the magnetoenhancement of the dissolution rate of oxygen
into water. The susceptibility of water near the
surface becomes slightly larger due to the
higher concentration of paramagnetic oxygen
relative to that of water in the bulk.
Magnetically induced convection accelerates
oxygen dissolution.
Interaction between magnetically induced dipoles
S
S
N
N
N
S
N
Magnetic fields
or
S
N
dia
S
para
Feeble magnetic materials in high magnetic fields
Weak magnet
Interaction between permanent magnets
S
N
S
N
S
N
N
S
N
S
repulsive
repulsive
S
N
N
attractive
N
repulsive
S
N
S
S
S
N
attractive
Energy of interaction
Interaction energy between magnetic moments
 0  μ a・ μ b 3μ a・ r μ b・ r 
U
 3 
 J 
5
4p  r
r

μa
r
μa(b)：magnetic moments of particle a and b [Am2]
r
： distance between magnetic moments [m]
μ a(b)∝ B
μb
Energy of this interaction changes
by the square of magnetic field intensity
This interaction between feeble magnetic materials
should be observed under high magnetic fields
Experimental
Samples
Pd (Paramagnetic)
  7.78  104   
Polyester thread
  12.02 103  kg/m 3 
Samples
Au (Diamagnetic)
  3.45 105   
  19.32 10 3  kg/m 3 
Shape of the sample
φ1mm×5mm （rod shape)
Samples were fixed at z=150 mm
fields
Superconducting
coil
Schematic figure of the
experimental set up
Experimental results
Pd-Pd
Au-Pd
0T
6T
Direction of
induced dipoles
0T
0T
1.0mm
Direction of
magnetic fields
Au-Au
6T
6T
1.0mm
repulsive
1.0mm
1.0mm
1.0mm
attractive
1.0mm
repulsive
Attractive and repulsive interactions between
magnetically induced dipoles
in feeble magnetic materials were observed
Interaction in many bodies system
Observation of the modification
of particles arrangement
Samples
Glass particles（spherical）
diameter ~0.8mm
   1.8 10   
Cu particles（Spherical）
5
diameter ~1.0mm
   9.7 10 6  
media
MnCl2 aqueous solution
（20～40wt% ）
Paramagnetic
Magnet bore
B
Samples
CCD camera
MnCl2 aq mirror Center of field
Schematic figure of
experimental set up
Results
glass in MnCl2aq 20wt%
glass in MnCl2aq 40wt%
Cu in MnCl2aq 40wt%
0T
0T
0T
4.7T
2.5T
5.5T
B
Magnetically induced
dipoles
Particles were connected like a chain due to the interaction
MagnetoHydrodynamic Motor
I
40 mm
F
B
Glass vessel
Electrode
(width=20 mm)
B
(//g)
FL
I=1.0 A
V = 50 V, I = 1.0 A
Monochlorobenzene(upper)
CuSO4 aq.(lower)
Fig. CuSO4aq. was rotating
in a glass vessel.
Lorentz force on aqueous solution rotated the liquid.
Summary
Creating a new process utilizing magnetic field
Process control
Moses effect, Enhanced Moses effect
Magneto-Archimedes levitation
Convection control
Material process
Crystal growth in levitating state
Magnetic orientation
Separation technique
Magneto-Archimedes separation
Poccoble application to the Nano-technology!