Investigation of arcing on fiber-formed nanostructured tungsten by pulsed plasma during steady state plasma irradiation

• Published in: Fusion engineering and design Vol. 112; pp. 156 - 161
• Main Authors: Yajima, M., Ohno, N., Kajita, S., De Temmerman, G., Bystrov, K., Bardin, S., Morgan, T.W., Masuzaki, S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2016; Elsevier Science Ltd
• Subjects: Arc heating; Arcing; ELM; Fiber-formed nanostructure; Heat; Heat flux; Heat transfer; Hydrogen; Linear plasma device; Nanostructure; Nanostructured materials; Plasma physics; Sheaths; Steady state; Superposition (mathematics); Transient heat load; Tungsten; Voltage drop; 28.52.-s (Fusion reactors); 28.52.Fa (Materials); Arcing; 52.55.Rk (Divertors); Tungsten; ELM; ohmic heating, arcs; Fiber-formed nanostructure; 52.50.Nr (Plasma heating by DC fields; Linear plasma device; Transient heat load
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2016.07.026

Arcing on fiber-formed nanostructured tungsten samples during ELM-like pulses was investigated using the superimposition of high power pulsed plasma on a steady state plasma with hydrogen gas in the linear plasma device Pilot-PSI. The ignition of arcing was observed when the floating potential of the samples was less than −75V with sufficient heat flux. The surface observation showed that the arc spots were not in the center, but in the peripheral area of the plasma column. Considering the plasma potential profile in the Pilot-PSI, the arcing occurred at the position where the heat flux and the sheath potential drop are sufficiently large.