CRP(2007-2011): Data for Surface Composition Dynamics Relevant to Erosion Processes

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Contents

Motivation

This CRP is organized to increase understanding of erosion processes in fusion devices, such as ITER. Plasma constituents, such as ions and electrons interact with the solid wall materials of fusion devices, leading to erosion of wall materials and later re-deposition of those materials. Several different processes can take place in such interactions, such as physical sputtering, reflection, and various chemical reactions. Often, the details of such interactions are not well enough known to understand and predict erosion processes in fusion devices. In many cases even the pathways of eroded materials are not well known. This CRP will use experimental and theoretical techniques to address these issues, resulting in a better overall understanding of erosion processes and possible methods to mitigate such effects in future fusion devices.


CRP(2007-2011) Research Activities

The 2nd Research Coordination Meeting

Publications

Discussion Topics of Research Coordinated Meetings

The list of data requirements for understanding Erosion in Fusion devices was formulated at the first RCM.

  • Phase diagram for the BeC system
  • Understand the behaviour of WC under irradiation
  • Ratios of sputtering yields of atomic Be to molecular BeD from deuterium saturated Be surface
  • Both physical and chemical differential sputtering yields from Be2C surfaces
  • D-retention level in pre-damaged W
  • He bubble growth rates as a function of temperature in W
  • Diffusion coefficients of hydrogen in W/Be/C compound materials, e.g. Be12W
  • Self-diffusion coefficients of W, Be, C for pure materials, materials with voids and mixtures of such materials
  • Oxidation of JET tiles (mixed Be C) at temperatures below 350ºC
  • Removal of Be/mixed co-deposited layers on tungsten and removal of hydrogen from such layers
  • H measurements of retention and erosion products for C+ and D+ implantation during simultaneous irradiation of W at elevated temperatures by means of a dual beam accelerator and LOS detection
  • MD model to assist in the interpretation of D retention in W during combined He, D irradiation
  • Measurements of reflection, sputtering, sticking, implantation and deposition of dynamically-hydrogenated (deuterated) carbon surfaces over the energy range 1 eV to 1 keV, with angular and energy distributed impacts of hydrogen, inert gases, carbon and hydrocarbons, and information on the final state (sputtered, reflected) spectra (angular, energy, rovibrational
  • Sound inter-potentials for H, C, W and Be for MD simulations
  • MD calculations to gain insight into the preparation of surfaces (D + C and He + C on W), and assessment of the applicability of the BCA model
  • Quantification of erosion products during simultaneous bombardment of W with D + C and He + C
  • Experimental data on absorption, adsorption and retention of H and D by Be and mixed materials for comparison with theory:
  • ab initio MD calculations on very large computer systems for the above processes involving Be and W
  • Surface loss probabilities and sticking for different hydrocarbons on various pure and mixed surfaces
  • Integrated modelling of retention in all materials, including mixed systems
  • High fluence retention measurements in ITER PFCs

Research Activities related to Erosion


Future Work

References

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