Quantitatively measuring the influence of helium in plasma-exposed tungsten

• Published in: Nuclear materials and energy Vol. 12; pp. 372 - 378
• Main Authors: Doerner, R.P., Baldwin, M.J., Simmonds, M., Yu, J.H., Buzi, L., Schwarz-Selinger, T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-08-2017; Elsevier
• Subjects: Helium; Plasma-material interactions; Retention; Tungsten; Helium; Retention; Plasma-material interactions; Tungsten
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2016.09.002

•Tungsten samples are exposed to 3He plasma to quantify their helium retention behavior.•The retention saturates quickly with helium fluence and increases only slightly from 4.3×1019He/m2 at 773K, to 7.5×1019He/m2 at 973K.•The helium content increases to 6.8×1020He/m2 when fuzz is formed on a sample exposed at 1173K, but the majority of the retained helium (5.1×1020He/m2) is found to reside below the layer of fuzz tendrils.
Tungsten samples are exposed to 3He plasma to quantify their helium retention behavior. The retention saturates quickly with helium fluence and increases only slightly from 4.3×1019He/m2 at 773K, to 7.5×1019He/m2 at 973K. The helium content increases dramatically to 6.8×1020He/m2 when fuzz is formed on the surface of a sample exposed at 1173K, but the majority of the retained helium (5.1×1020He/m2) is found to reside below the layer of fuzz tendrils. Additional tungsten samples were exposed to either simultaneous, or sequential, D/He plasma, followed by TDS. Measurements show the majority of the D retained during simultaneous exposures is located in the near surface region of helium nano-bubbles. No deuterium was detected in any of the samples after the heating to 1273K, but 67% of the helium was released from simultaneously exposed samples, and only 23% of the helium was released from the sequentially exposed samples.