VDU/LEI project in FUSION: background, goals,
methods and expected results
(PhD student Birutė Bobrovaitė, Dr. Liudas Pranevičius)
Project title:
Characterisation of W-Coatings for Fusion Applications
Project duration 30 months originated from 2006 01 01
The project is coordinated by
the Materials Research and Testing Laboratory,
Lithuanian Energy Institute, Kaunas.
The project partner is
the Physics Department of the
Vytautas Magnus University, Kaunas.
Outline of the presentation
o
o
o
Goals of the work;
Work package;
Expected results.
Main problem
Mechanism of restructuring and surface relocations under high-flux
irradiation at elevated temperatures.
Material erosion by continuous or transient plasma ion and neutral
impact, the subsequent transport of the released impurities through and by
the plasma and their deposition and/or eventual re-erosion constitute the
process of migration.
Due to erosion mechanism and re- deposition materials will interact on
plasma facing surfaces.
....is to understand physical phenomena of mechanical properties of W
and to reduce the impurities in the main chamber
The goal of the research is
 the fabrication of W films to be used in plasma-facing
components in fusion devices, and the understanding of the
mechanism of physical phenomena initiating modifications of
mechanical properties of W-based thin films on carbon based
substrates under high-flux, low-energy H+ ions irradiation in the
range of temperatures up to 1000°C.
Descriptions of work
Fabrication of W coatings by magnetron sputter deposition;
Structural and compositional investigation of W coatings;
 Plasma/ion beam H exposure of W coatings ;
Studies of W coatings properties after hydrogen ion irradiation ;
Modelling of the surface restructuring and re-deposition effects
in W film under high-flux, high-fluence, low-energy hydrogen ion
irradiation;
Fabrication of W films
Magnetron sputter deposition of W films on carbon based
substrates.
Thickness – 3-10 m.
The film surface area – 17  20 cm.
Thickness homogeneity – better than 20%.
Irradiation experiment
Extraction of ions from thermionic arc plasma generated in hydrogen
working gas.
Pulsed plasma immersion hydrogen ion implantation using
acceleration voltage up to 500 V.
Hydrogen beam implantation using Kauffman ion source (2-5 mAcm2, 300 eV) using facilities of the Poitiers University (France).
Characterization
Microstructure and grain size of films by XRD analysis;
Surface morphology analysis using SEM and AFM analysis;
Film and interface compositional analysis using glow discharge optical
emission spectrometry (GDOES) analysis;
Film resistivity measurements using four probe method;
Film thickness homogeneity analysis using large area laser
interferometry views;
Studies of film nano-hardness and film erosion properties in
collaboration with the Laboratory of Metallurgic Physics of the Poitiers
University (France).
Modelling
It is planned to consider surface redeposition and reconstruction
effects on composition and structure of W films initiated H+
irradiation.
The modelling includes three processes:
surface diffusion (thermally activated process),
ballistic surface atom relocation (ion irradiation activated
process)
and redeposition of sputtered atoms (W atoms, oxygen, etc.)
arriving from plasma.
Expected results
To form dense nanocrystallline thin W films (optimization of film
deposition parameters for thickness and homogenity of W films);
To investigate structure and composition of W cotings;
To commit iradiation experiments;
To model surface redoposition and reconstruction effects on
composition and structure of W films initiated initiated H
irradiation.
Work package list
Work
package
No1
Work package title
Lead
contractor
No2
Personmonths3
Start
month4
End
month5
Deliverable
No6
WP1
Fabrication of W coatings by
magnetron sputter deposition
1a
4
0
8
D1
WP2
Structural and compositional
investigation of W coatings
1b
8
0
8
D2
WP3
Plasma/ion beam H exposure
of W coatings
1b
14
8
27
D3
WP4
Studies of W coatings
properties after hydrogen ion
irradiation
1b
10
20
30
D4
WP5
Modelling of the surface
restructuring and re-deposition
effects in W film under highflux, high-fluence, low-energy
hydrogen ion irradiation
2c
18
6
30
D5
TOTALS
54
Thank You for your attention