4th Japan-France Cooperative Program Seminar

Nara - Japon - 4/7 Oct 2004

Electromagnetic levitation Electromagnetic levitation under pulsated magnetic fieldunder pulsated magnetic field

J. ETAY and B. BARDET

EPM-Madylam ENSHMG BP95 38402 S t Martin d'Hères Cedex (FRANCE)

Local balance e.m. shaping ρ

us2

2+2γκ+ρgzs +

Bs2

2μ=cst

LevitationLevitation

Global balance e.m. levitation Mg= j×B( )dV

V∫

Levitation : main instabilitiesLevitation : main instabilities

global oscillations

fv =

12π

g2Δzo

to be eliminated

local oscillations

f2 =

12π

8γ

ρa3

to be promoted

Cummins D.L. and Blackburn, D.A., 1991, Journal of Fluid Mechanics, vol 224

Why ?Why ?

levitation - centering heating-exciting

250 kHz 350 kHz0,1 à 10 Hz

Sketch of the TEMPUS-MSLSketch of the TEMPUS-MSL

performe measurements of thermophysical properties of liquid metal alloys, in space

How ?How ?

Surface tension γ =

38

π ⋅M ⋅ fmeasured2

Viscosity ρν=

320

⋅π⋅Ma

⋅1

τmeasured

no gravity

Lamb, H, 1975, Hydrodynamics, Cambridge University Press

Levitation under pulsated magnetic fieldLevitation under pulsated magnetic field

a good tool to more accurate measurementaccurate measurement

easy to use +no-contact + double checking

Measuring equipmentMeasuring equipment

LCω12 =1

With our power suppy

I

f1

Δf1 t( ) =fsampling

25f1max− f1min( ) tn( )

n=1

25

∑

Experimental facilityExperimental facility

Set-upSet-up

Nickel physical propertiesNickel physical properties

Characteristics of the experimentCharacteristics of the experiment

achieved levitation

achieved melting

no thermal equilibrium

Experimental ResultsExperimental Results

pargon=2,1.10−5bar

Spectra of Io(t)Spectra of Io(t)

pargon

= 2.10

-5

b a r

f2=0 Hz

f2=8.5 Hzf2=7.5 Hz

f2=8 Hz

Comparison ∆f1 and peak valuesComparison ∆f1 and peak values

∆f1 is a relevant for the global stability of the load

ConclusionsConclusions

Stable electromagnetic levitation achieved

Original system of measurement tested

Detection of the state of global stability of the load achieved

Can be use on all induction system powered by triode power supply

To be validate : remote control of f2

= automatic excitation of the first resonance.