ecloud´12 novel types of anti-e cloud surfaces · sey of graphene oxide critical experimental...

Novel Types of Anti-e Cloud Surfaces

I. Montero1, V. Nistor2, L.Aguilera1, L.Galán2, D. Raboso3, L.A.

González2, M.E. Dávila1, P. Costa Pinto4, M.Taborelli4 and

F.Caspers4

1ICMM-CSIC 2UAM, 3ESA, 4CERN

ECLOUD´12

• Main goals

• Basic Objectives and Concepts

• Critical Experimental Activities

• Anti-ecloud-Multipactor Coatings:

SEY Research

• Summary and Conclusions

Isabel Montero, ICMM-CSIC ECLOUD’12

Outline

Main goals

To mitigate:

1. The electron cloud

and its adverse consequences

2. The multipactor effect

in space-related

high-power

RF hardware

Isabel Montero, ICMM-CSIC

Development of coatings with

low secondary electron

emission yield (SEY)

p

sample

Basic Objectives and Concepts

by surface material of low SEY

by surface roughness of high aspect ratio and density

Very low SEY

Very low RF

surface resistance

► by optimization of depth

of surface roughness

Very slow aging in air by stable surface material

MAIN OBJECTIVES:



Very low SEY

Very low RF

surface resistance

►

Very slow aging in air

MAIN OBJECTIVES:


like Au / roughAg

max < 1.5

E1 > 200 eV

Stability one year

close to Ag

Rs< 3x Rsurf(Ag)


Critical experimental activities

MAIN CONCEPTS: Multilayer coating

roughness layer

conductive

layer

low-SEY layer

Multilayer coating


Ag, Cu, Au roughness layer

conductive

layer

low-SEY layer

Ag, Cu

Rh, TiN, …,

Au, Rh, Ir,

TiN, BC,… 50 – 1000 nm

5 – 20 μm

50 – 500 nm

5 – 50 nm

Material Thickness



SEY suppression increases with roughness shape

(aspect ratio, density, profile)

RF surface resistance increases with roughness size

Multilayer coating




SEY and Roughness

to be optimized

Ag, Cu, Au roughness layer

conductive

layer

low-SEY layer

Ag, Cu

Rh, TiN, …,

Au, Rh, Ir,

TiN, BC,… 50 – 1000 nm

5 – 20 μm

50 – 500 nm

5 – 50 nm

Material Thickness Multilayer coating



ITI Innovation Triangle Initiative

Optimization of Surface Roughness of Anti-Multipactor

Coatings for Low Insertion Losses and Secondary

Emission Suppression for High Power RF Components in

Satellite Systems

ESA PROJECT

Departamento de

Física Aplicada

Departamento de

Física Aplicada

Anti-Multipactor Coatings

Two different kinds tested


Aluminum

Nickel Silver etched

Au 2 µm

Magnesium

device

MgO

5 µm

Au, Ag

2 µm

2 µm

1µm Rr /Rs = 2.2 @ 9.5 GHz 1µm Rr /Rs = 2.4 @ 12 GHz

Gold-coated anomag Gold-coated etched silver

1/e

skin depth

silver 2

1 gold

silver 1

vacu

um

Bu

lk

Al


Insertion losses /surface rough. is a crucial issue

Ni

z

At sufficient high ω, the induced Is are confined by the skin

effect to a surface region of poor because of surface

roughness


fo

dc

fo

dc

f πμ

ρ δ

o

dc


f R dc o

dc

s

1

surface region formed by a coating of thickness dcoat over a substrate,

A Layered Model for RF Surface Resistance Calculation

-0.5

0.0

0.5

1.0

0 0.5 1 1.5 2 2.5 3

Distance along flat surface x /p

Heig

t over

flat

surf

ace h

/p rough surface

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

RF current

A: Factor of increased current path at

depth z due to roughness

Rs = RF SURFACE RESISTANCE

Resonant circuit

Anti-ecloud Coatings

0 ·

11dze

AR

z

0 ·

11dze

AR

z

0 ·

11dze

AR

z

0 ·

11dze

AR

z

1.0

1.5

2.0

0 2 4 6 8 10 12

Normalized Roughness Heigh h o /

R /

Ro

Our model

Filipovic (2007)

ho/p = ½3

/p = ¼ ho/p

=

R/R

o

Using this function with three fitting parameters it is possible

to fit the results of Filopovic or Matsushima

M V Lukic, D S Filipovic:; IEEE, 55, 518-525 (2007)

A. Matsushima and K. Nakata: Elect. Commun. Jpn. 89 (1) 1 (2006).

ho/

A Layered Model for RF Surface Resistance Calculation

h p -- Matshusima (2006)

_ _ _ _ Our model

Liquid

Chemical Bath

Deposition

Chemical Etching

Gas (UHV)

Evaporation

Sputtering

Anodization Ion implantation

Physical Vapor

Deposition

Solid

Particle

Deposition


Deposition Methods



RF ion gun control units

pressure gauge and microAmp

turbo pump

RF ion gun

spherical prep chamber

UHV preparation chamber with RF ion gun for

deposition of anti-multipactor coatings

Departamento de

Física Aplicada

Departamento de

Física Aplicada


Selected materials

• Silver

• Gold

• NEG

• Graphene like coatings

• Magnetic and dielectric/metal

composites:

particulated surfaces


Selected materials

• Silver


Al bulk

Ni

Ag

SEY Characteristics

of Mo-Masked, Ion-Textured Silver

Al bulk

Ni

Ag 40 µm

10 µm

Al bulk

Method for producing

1. uniform,

2. highly textured surface

on high-conductivity Ag

Device


Mo cone Ar ion beam

Al bulk

Ni

Ag

Ar ion beam

Mo cone

SEY Characteristics

of Mo-Masked, Ion-Textured Silver

Al bulk

Ni

Ag 40 µm

10 µm

Al bulk

Method for producing

1. uniform,

2. highly textured surface

on high-conductivity Ag

Device


SEM of Ag treated coating

Surface roughness depends on

1. Ion density

2. Ion energy

3. Time


The purpose was to develop a basicaIly Ag surface having

very low-SEY characteristics.

SEY of Ag plating after treatment and exposure to the air.

Its untreated

surface

displays

relatively

very high

levels of

SEY

SEY of Ag treated coating



HEATER

SAMPLE

Growing rough Ag coating CBD Chemical Bath Deposition Method

electrodes

Electrical

Contact

Preparation conditions

Growth Temperature 50ºC

TEA

AgNO3

SnClx

With and without Efield

Selected materials

• Gold


Nanometric Au layer to prevent aging process

to decrease SEY

ALUMINIUM

SILVER

NICKEL

GOLD



Au coated CuO nanowires


First

stadies of

NW

growth

XPS

NW

0 200 400 600 800 10000.0

0.5

1.0

1.5

2.0

SE

Y

Primary Electron Energy (eV)

Cu foil +Au

CuO 500ºC-2h +Au

CuO 500ºC-4h +Au

CuO 500ºC-6h + Au

CuO 500ºC-8h + Au

CuO 500ºC-10h +Au

SEY experimental measurements Au coated CuO nanowires


SEY of Nano-structured Materials

aspect ratio 1:1000

Selected materials

• NEG

Non-Evaporable Getter


Substrate: Rough Al

Etching time (s)

SEY results

Correlation between SEY and Ra



Aluminium etched, HCl

profilometry measurements

t




EDC curves for Al



NEG coated rough Al

SEM

NEG

Al



AFM image

NEG/flat Al


SEY of Rough NEG

Rough NEG, before activation Rough NEG, after activation


Selected materials

• Graphene like coatings


0 200 400 600 800 1000 1200 1400 1600 18000.0

0.2

0.4

0.6

0.8

1.0

Al foil-aC

Al 60s-aC

Al 120s-aC

Al 150s-aC

Al 210s-aC

Al 300s-aC

Al 360s-aC

SE

Y

Primary Electron Energy (eV)

SEY <1


Introduction: a-C coated rough Al

AFM image

aC/flat Al

SEM image

aC/roughAl

Graphite and Graphene Oxide (GO)


The results reveal that the GO sheets are rough and the

structure is predominantly amorphous due to distortions from

the high fraction of sp3 C−O bonds. Isabel Montero, ICMM-CSIC

SEY of graphene oxide



Selected materials

• Magnetic particulated

surfaces: ferrites



SEY OF MAGNETIC PARTICULATED

SURFACES: ferrites

the surface coating

including a multitude of

particles sized

Reexamining the effects of

magnetized surfaces on the SEY

properties

primary


Selected materials

• Composites: dielectric/metal



New Insights into metal/dielectric particulated

surfaces and their SEY properties composite



surfaces and their SEY properties

Composite

Alumina/aluminium




surfaces and their SEY properties

+ +

+ + + + + + +

+ + + + +

substrate

Secondary

electrons

Primary

electrons SEY<<1

Dielectric

metal

SUMMARY

Anti-eCloud coatings exposed to the air.


SE

Y

Rough

Surfaces Flat

Surfaces


Summary and Conclusions

Future work

This work is directed to providing surfaces

having extremely low secondary electron

emissions.

The molybdenum-masked, ion-textured

silver surface wiII be a promising material for

inhibiting multipactor.

Extremely reduction of SEY is observed in

different particulated metal/dielectric systems.


As far as the achievement of low SEY coatings

should rely heavily on surface morphologies with

roughness of high aspect ratio, insertion losses due

to surface resistance become a crucial issue.

It is necessary the optimization of surface

roughness of anti-multipactor coatings for low

insertion losses and secondary emission

suppression for high power RF components in

satellite systems

.


Thank you for your attention

ecloud´12 novel types of anti-e cloud surfaces · sey of graphene oxide critical experimental...

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