Hydrogenic retention of high-Z refractory metals exposed to ITER divertor-relevant plasma conditions

被引:20
作者
Wright, G. M. [1 ,2 ]
Alves, E. [3 ]
Alves, L. C. [3 ]
Barradas, N. P. [3 ]
Carvalho, P. A. [4 ,5 ]
Mateus, R. [4 ]
Rapp, J. [1 ,6 ]
机构
[1] EURATOM FOM, FOM Inst Plasma Phys Rijnhuizen, Nieuwegein, Netherlands
[2] MIT, Plasma Sci & Fus Ctr, Cambridge, MA 02139 USA
[3] Inst Tecnol & Nucl, P-268693 Sacavem, Portugal
[4] Inst Super Tecn, Inst Plasma & Fusao Nucl, Assoc Euratom IST, P-1049001 Lisbon, Portugal
[5] Inst Super Tecn, Dept Engenharia Mat, ICEMS, P-1049001 Lisbon, Portugal
[6] EURATOM, FZ Juelich, Inst Energy Res, D-52425 Julich, Germany
关键词
DEUTERIUM RETENTION; LOW-ENERGY; MICROSTRUCTURAL EVOLUTION; THERMAL-DESORPTION; ION IRRADIATION; INDUCED DEFECTS; HIGH FLUENCES; TUNGSTEN; MOLYBDENUM; BACKSCATTERING;
D O I
10.1088/0029-5515/50/5/055004
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
Tungsten (W) and molybdenum (Mo) targets are exposed to the plasma conditions expected at the strike point of a detached ITER divertor (n(e) similar to 10(20) m(-3), T-e similar to 2 eV) in the linear plasma device Pilot-PSI. The peak surface temperatures of the targets are similar to 1600 K for W and similar to 1100 K for Mo. The surface temperatures and plasma flux densities decrease radially towards the edges of the target due to the Gaussian distribution of electron density (n(e)) and temperature (T-e) in the plasma column. A 2D spatial scan of the W and Mo targets using nuclear reaction analysis (NRA) shows D retention is strongly influenced by surface temperature in the range 800-1600 K and this dependence dominates over any plasma flux dependence. NRA and thermal desorption spectroscopy (TDS) show no clear dependence of retention on incident plasma fluence for the W targets with retained fractions ranging from 10(-8)-10(-5) D-retained/D-incident. NRA and TDS for the Mo targets show retention rates a factor of 4-5 higher than the W targets and this is likely due to the lower surface temperatures for the Mo plasma exposures. NRA also reveals a thin boron layer on the Mo targets but the presence of boron does not correspond to a significant increase in D retention. Overall hydrogenic retention in W and Mo is shown to be low (D-retained = 10(19)-10(20) Dm(-2)) despite exposure to high plasma flux densities (similar to 10(24) Dm(-2) s(-1)). This is likely due to the elevated surface temperature due to plasma thermal loading during exposure.
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