J=σT 4 Jo ž ef Stefan Institute SEWG meeting Cadarache, June 2009 D retention in inhomogeneous...

j=σT4 Jožef Stefan Institute SEWG meeting Cadarache, June 2009

D retention in inhomogeneous layers and castellation gaps by micro-NRA

WP09-PWI-01-02/MHEST Primož Pelicon, Primož Vavpetič, Zdravko Rupnik, Iztok Čadež

Microanalytical Centre, Department for Low and Medium Energy Physics (F2),Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia

Association EURATOM-MHEST

http://www.rcp.ijs.si/~mic


Contents:

1. Introduction: 2 MV tandetron

2. Elastic Recoil Detection Spectroscopy (ERDA)

3. High Energy Focused Ion Beam: micro-ERDA and micro-NRA

4. Conclusion


RBS/ERDA :Beam: 4230 keV 7Li2+, Sample tilted 75°RBS detector at 160°, ERDA detector at 30°ERDA detector equipped with 11 µm Al foilDose controlled by mesh charge integrator Pelicon et al., NIM B 227, 591 (2005)

2. Elastic Recoil Detection Analysis (ERDA) for hydrogen depth profiling in PFCs


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Measurement Three-layer simulation Single layer simulation

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Li-ERDA, three-layer model Li-ERDA, one-layer model BAM reference value Round-robin average value

Results of the round robin measurements "Hydrogen in Silicon", organized by “Bundesastalt Für Materialforschung und –prüfung” (BAM), Berlin. The result of the IJS, obtained with the Elastic Recoil Detection Analysis (ERDA) with Li ions, is marked by red circle, average value by thick blue line. Result of the laboratory 1 is the result of BAM. (Source: U. Reinholz, H.P. Weise, BAM Berlin, Round robin test "Hydrogen in Silicon", Results sent to the participants of the round-robin, Pelicon et al., NIM B 227, 591 (2005))


In 2008, ERDA has been configured inside new measurement chamber at JSI for studies of hydrogen in surfaces, thin films, dinamic processes of interaction of hydrogen and surfaces.

Fig.1: Erda spectrum of a:C:D film for calibration of D detection methods, measured by 4.2 MeV 7Li beam (In collaboration with Th. Schwartz-Seliger, IPP Garching, sept. 2008)


3. High Energy Focused Ion Beam: micro-ERDA and micro-NRA

Focused beam formation:Magnet quadrupole triplet lensis focusing the beam at the analyzing object.Example: beam envelope for the focusing of 7Li2+ beam to 3x3 µm2

Blue: horizontal planeRed: vertical plane


Data acquisition:All detectors (incl. Chopper RBS) Connected to the sameMultiplexing ADCDetector event:(E,i,Ux,Uy)

On-line datasorting

Off-linedata sorting(list modemeasurements)

PIXE De t. RBS De t.

Protonskižarek

Pre isko va nid e l vzo rc a

Prem iki žarka

SE De t.

STIM Thin samples

AnnularRBS Det.

Deflecting coils (x,y)

Sample positioned in the focal plane

Ion beam

RBSdetector

Chopper(dose normalization)

Quadrupole lens

ERDA With 75º tilted sample

Foil


On-line datasorting



On-line datasorting


PIXE De t. RBS De t.

Protonskižarek

Pre isko va nid e l vzo rc a

Prem iki žarka

SE De t.

STIM Thin samples

AnnularRBS Det.

Deflecting coils (x,y)

Sample positioned in the focal plane

Ion beam

RBSdetector

Chopper(dose normalization)

Quadrupole lens

ERDA With 75º tilted sample

Foil


Areal distribution of molybdenum (islands)measuredby Li-beam excited X-ray emmision (LIXE)

and simultaneously measuredhydrogen lateral distribution by Li-beam ERDA over an area of 1240 x 450 µm2. Sensitivity of the method is 0.1 at. %.

1240 µm

450

µm

Mo Lα

Hydrogen

Distribution of hydrogen is anti-correlated with the distribution of molybdenum. Hydrogen retention is higher in the surface of uncoated graphite.

Micro-ERDA: lateral mapping of hydrogen at plasma-exposed surface of castellated limiter[1]

[1] Litnovsky et al, J. Nucl. Mater. 337-339, 917 (2005).


Cleavage direction

Plasma-exposed surface

Example: Deuterium depth distribution in Carbon Fibre Composite NB31 after deuterium exposure experiment in Textor [2]

Scanned region

As the surface roughness strongly affects the ERDA due to sample tilting to an angle of 75°, micro-NRA with the 3He beam for deuterium detection is alteranatively developed, being less sensitive to surface topography (no sample tilting required). Micro-NRA: 3He focused ion beam with 5 x 5 µm2 with 500 pA. Beam size limited by the brightness of the ion source for neg. 3He beam production. Ion source reliability problem solved in 2008.

Micro:NRA with 3He beam and D(3He,p)4He formation


D counts

90 μm

500 μm

Cleaved CFC NB31: D penetrates below surface (50 micrometers) in distinct points due to CFC micro-structure (fibre, pores)

Kreter et al, Deuterium retention in different carbon materials exposed in TEXTOR, J. of Phys.- Conf. Ser. 100 (2008) 062024.

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CFC NB31 deuterium depth profile in cleavage


3. Conclusion

Fig.1: Lithium charge exchange channel with heather/TC separated from Li melt, installed within the project PWI-08-TA-06/MHEST/PS/01, for 3He beam production (Source: HVEE)

Ion Beam Analytical methods for hydrogen (deuterium) detection for PWI Studies were configured during the last three years and are now available for work within MHEST projects, as well as for Mobility visits.

J=σT 4 Jo ž ef Stefan Institute SEWG meeting Cadarache, June 2009 D retention in inhomogeneous...

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