Surface modification of tungsten due to carbon ion implantation

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Surface modification of tungsten due to carbon
ion implantation

• A. Martinavicius

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Introduction

• The first wall of future fusion devices will be
  made from the materials W, C and Be.
• The W tiles in the divertor chamber are exposed
  to high heat and carbon impurity fluxes which
  will lead to high C concentrations in the W.

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Schematic view of model

• Not all atoms are immediately sputtered.
• Some atoms are activated and relocate.
• Other atoms after relocation also are sputtered.

Target
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Model
Ii flux of arriving ions, Yi sputtering yield
aij sticking coefficient
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Calculations
C YW 0.37 YC 0.34 aCW0.61 aCC1 aWW? aWC?
C YW 0.37 YC 0.34 aCW0.61 aCC0.8 aWW0.4 aWC0.3
CH3 YW 0.37 YC 0.68 aCW0.61 aCC1 aWW? aWC?
CH3 YW 0.37 YC 0.68 aCW0.61 aCC0.72 aWW0.5 aWC0.4
K. Krieger, J. Roth / J. Nucl. Mater. 290-293
(2001) 107-111
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Calculations (2)
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Diffusion data

• D 0 m2/s,
• T 3.66 (103 K-1)
• D 5 10-23 m2/s,
• T 1.29 (103 K-1)
• D 1.5 10-22 m2/s,
• T 1.03 (103 K-1)
• D 5 10-21 m2/s,
• T 0.93 (103 K-1)