Transient Model of Fuzzy Tungsten Growth, Annealing, and Erosion in Fusion Environments

Under fusion conditions, tungsten can develop a porous (fuzzy) surface microstructure [1]. This is concerning for most metallic divertor materials, especially during Edge Localized Mode (ELM) events with high particle bombardment [2,3]. If this fuzzy layer breaks off, it could introduce significant high Z impurities into the bulk plasma, potentially quenching the fusion reaction [4]. Several models have been proposed to model fuzz growth and erosion [4-6]. In this study, we combine elements of several prior theories to model transient growth, annealing, and erosion processes in fuzzy tungsten using a zero-dimensional kinetic model. We find steady-state conditions for fuzz layer thickness – including novel pseudo-steady-states induced by ELMs – and compare to previous models. Extensions to higher dimensionalities and tungsten alloys will be addressed.

 

[1] M. J. Baldwin and R. P. Doerner, Nucl. Fusion 48, 035001 (2008).

[2] H. Zohm, Plasma Phys. Contr. F. 38, 105 (1996).

[3] G. Sinclair et al., J. Nucl. Mater. 508, 26-32 (2018).

[4] R. P. Doerner et al., Nucl. Fusion 51, 043001 (2011).

[5] T. J. Petty et al., Nucl. Fusion 55, 093033 (2015).

[6] G. De Temmerman et al., Plasma Phys. Contr. F. 60, 044018 (2018).