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The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006 M.Valentino, C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri Istituto Nazionale Fisica Nucleare, Legnaro National Laboratories, Legnaro (PD), Italy Magnetometry and Non Destructive Evaluation

M.Valentino, C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

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Magnetometry and Non Destructive Evaluation. M.Valentino, C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri Istituto Nazionale Fisica Nucleare, Legnaro National Laboratories, Legnaro (PD), Italy. Outline:. Sensors for magnetometry - PowerPoint PPT Presentation

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Page 1: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

M.Valentino, C. Bonavolontà Coherentia CNR -INFM, Naples, Italy

V. Palmieri

Istituto Nazionale Fisica Nucleare, Legnaro National Laboratories, Legnaro (PD), Italy

Magnetometry and Non Destructive Evaluation Magnetometry and Non Destructive Evaluation

Page 2: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Outline:

Sensors for magnetometry

Design of high sensitivity magnetic sensors working in unshielded environment

Giant Magneto Resistance (GMR) sensors

GMR devices for magnetic field detectors and Eddy-current measurements

Real time correlation between magnetic signal and corrosion on bulk Niobium

Real time magnetic detection of fatigue stress in metals

2D high sensitivity magnetic image

Page 3: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Magnetic field (Tesla)

Magnetic sensors & applications

10-4

10-5

10-6

10-7

10-8

T

10-9

10-10

10-11

nT

10-12pT

10-13

10-14

10-15fT

Magnetometer field resolution

Applications

NDE

Bio

mag

net

ic a

pp

lica

tio

ns

Hall

Flux-gate

HTS

LTS

GMR

corr

osi

on

Fat

igu

e

Page 4: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Main magnetic sensors characteristics

Sensor Range Temperature

stabilitySensitivity

(Unsh.Environment) Cost

Hall probe ± 10 mT low0.8 T /Hz @

1Hzlow

Flux Gate ± 70T low236 nT/Hz @

1Hzmedium

GMR ± 50 T high320 pT /Hz @

1Hzlow

SQUID ± 5T low176 pT/Hz @

1Hzhigh

Page 5: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

GMR Sensors Principles

Alloy and base transition metal targets (Ni/Fe, Co/Fe, Co/Cr/Pt, Pt/Mn, Ta, Cu, Au)

Ferromagnet Co

Ferromagnet CoNon magnetic metal Cu

No external Magnetic Field

J JHigh Electrical Resistance

J JLow Electrical Resistance

Ferromagnet Co

Ferromagnet CoNon magnetic metal Cu

Applied external Magnetic Field

Giant Magneto Resistance, (1988)

Page 6: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

R/R ~ 10%-20%

GMR Sensors Principles

Electrical resistance variation due to the magnetic field

Page 7: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

magnetic field noise responses in magnetic unshielded environment

Comparison between magnetic field responses of magnetometer, 1st and 2nd order gradiometer

0.01 0.1 1 10 100 1000 100001E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

2st grad

INFM 1st grad

INFM mag

B (

Tes

la)

Hz

Page 8: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

m

r

b

2

1

z

1st order Radial gradiometer

m

r

b

2 1

z

1st order off axis gradiometer

m

r

b

2

1

z

1st order transverse gradiometer

Useful Gradiometers configuration

dz

dBzdx

dBzdz

dBx

m

r

b

3

1

b

2

z

2nd order transverse gradiometer

2

2

dz

Bd x

Page 9: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

detector

reference

1

2

3 4

5

Experimental set-up. 1) Niobium disk; 2) Teflon vessel filled with 40ml of Acid solution; 3) Fluxgate magnetometers sensors housed in a Plexiglas holder: detector and reference magnetometers are in a first order gradiometer configuration; 4) Aluminium shields; 5) mu-metal shield.

Niobium Buffered Chemical Polishing

BCP Solution :-Hydrofluoric acid -Phosphoric acid

Page 10: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5

0.1

1

112111.8111.6111.4111.2111 without solution

nT /(

Hz)

1/2

Hz

Niobium corrosionBCP 1:1:1 to BCP 1:1:2 increasing the H3PO4 percentage the magnetic signalIntensity increase

Page 11: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

The average magnetic field is plotted versus etching rate.

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1 1.5 2 2.5 3

Etching Rate [micron/min]

nT/H

z1/2

Niobium corrosion

Page 12: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Cell width

(mm)

w[g] at 4V

weighing

w[g] at 4V

field

w[g] at 7V

weighing

w[g] at 7V

field

8 0,012 0,011 0,025 0,048

16 0,023 0,020 0,035 0,020

24 0,05 0,032 0,13 0,035

lF

BMr

t

w

0

24

Corrosion rate

Corrosion Rate evaluationCorrosion Rate evaluation

According to Faraday law

cells 50 mm long

Not explained by Faraday law

Page 13: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Curve cathode

Magnetic field distribution

Flat cathode

Line-scan

0 20 40 60 80 100 120

2.10

2.45

2.80

3.15

3.50

ma

gn

etic

fie

ld (T

)

mm

flat cathode curve cathode

-40 -20 0 20 40

0.0

0.1

0.2

0.3

0.4

0.5

0.6

curr

ent

densi

ty (

A/m

m^2

)

mm

flat cathode curve cathode

nF

jStMw

Cells with different cathode geometries

Optimization of the Cu-polishing

Cells with different cathode geometries

Optimization of the Cu-polishing

Page 14: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

GMR 2nd order gradiometer

GMR 2nd order electronic gradiometer. It detects the in plane magnetic field component reducing the environmental noise

1st GMR

2nd GMR

3th GMR

2nd order Radial gradiometer

m

r

b

3

1

b

2

z

2

2

dzBd x

Page 15: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

GMR testing on the electropolishing

The solution used: 55% Phosphoric acid45% n-buthanol

Flux gate 1st order gradiometer imaging GMR 2nd order gradiometer imaging

Page 16: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

5 mm

4 mm

GMR sensors for Eddy-current probe

Circular excitation coil to induce eddy current into the specimen

Page 17: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Back side

Surface

GMR Eddy current probe has been tested using a specimen of AL-Ti alloy with rivets and artificial slots

GMR Eddy Current probe testing

Slot 1 Slot 2Slot 1 Slot 2

Page 18: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

50 mm

20 mm

Detection of sub- millimetric scratch on Niobium surface

20

m

m50 mm

Artificial sub millimetric scratches have been produced on the Nb surface

Test sample GMR imaging

Page 19: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Working frequency: 3MHz

50 mm

20 mm

Test sample Eddy Current induction coil imaging

50 mm

20

mm

Comparison with conventional Eddy current induction system

Page 20: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Physical etching of titanium surface

Page 21: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

mm

mm

GMR Eddy current Probe detection

Page 22: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Magnetic field scanner to detect fatigue effect in metals

System characteristics Speed: 3mm/s (0-6/mm/s)

Spatial resolution: 0,1mm

Position Reproducibility : 0,05mm

Magnetic field signal Reproducibility 0.01%-5 0 5 10 15 20 25 30 35

-17,3

-17,2

-17,1

-17,0

-16,9

-16,8

-16,7

-16,6

-16,5

-16,4

-16,3

-16,2

-16,1

-16,0

-15,9

Riproducibilità tra due misure successive

Bx (T

)

Posizione (mm)

Prima Dopo

Page 23: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Detection of the localized Fatigue process in steelMonitoring the Magnetic field

… around the cut

0 20 40 60 80 100 1203,8

4,2

4,5

4,9

5,2

5,6

Campione P3; sensore fermo sull'apice del tagliorosso -carico; verde- scarico

Bx

(T

)

(Rif. carico) -20 0 20 40 60 80 100 120 140-18,2

-17,8

-17,5

-17,1

-16,8

-16,4

-16,1

Campione P3; sensore a 20 mm dall'apice del tagliorosso -carico; verde- scarico

Bx

(T

)

(Rif. carico)

…20 mm far from the cut

Page 24: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Sub-millimetric Magnetic field imaging

9,5 kN 0,0 kN

23 kN 0,0 kN

0,1 mm

0,1 mm

Page 25: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Surface plastic deformation imaging, preliminary results

GMR responses, spatial resolution: 50m

Magnetic field resolution: 1nT/Hz1/2

mm

mm

0,1 mm

Page 26: M.Valentino,  C. Bonavolontà Coherentia CNR -INFM, Naples, Italy V. Palmieri

The International Workshop on THIN FILMS APPLIED TO SUPERCONDUCTING RF AND NEW IDEAS FOR PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY M. Valentino, Padova-Italy, October 9 – 12, 2006

Conclusions Emerging magnetic sensors, like GMR, allows to detect with high sensitivity the magnetic field produced during the following process:

The ongoing corrosion of the metals electropolished as Cu and Nb.

The Fatigue stress effects in steels.

2D magnetic field imaging of sub-millimetric defects and plastic deformation in metals with a spatial resolution better than 100 micron.

Development of GMR Eddy current probe

Detection of surface sub-millimetric defects and scratches with depth less than 0.1 mm in Niobium plate.

Detection of corrosion effect with a depth less than 100micron, due to Ion etching on Titanium surface.

ProspectiveDevelopment of magnetic sensors array to measure the magnetic field during the electropolishing process of metals on non- planar geometry.