Interaction of nitrogen ions with beryllium surfaces

[摘要] The interaction of energetic nitrogen projectiles with a beryllium surface is studied using a highly sensitive quartz crystal microbalance technique. The overall mass change rate of the beryllium sample under N-2(+) ion impact at an ion energy of 5000 eV (i.e. 2500 eV per N) is investigated in situ and in real-time. A strong dependency of the observed mass change rate on the nitrogen fluence (at constant flux) is found and can be attributed to the formation of a nitrogen-containing mixed material layer within the ion penetration depth. The presented data elucidate the dynamics of the interaction process and the surface saturation with increasing nitrogen fluence in a unique way. Basically, distinct interaction regimes can be discriminated, which can be linked to the evolution of the surface composition upon nitrogen impact. Steady state surface conditions are obtained at a total cumulative nitrogen fluence of similar to 80 x 10(16) N atoms per cm(2). In dynamic equilibrium, the interaction is marked by continuous surface erosion. In this case, the observed total sputtering yield becomes independent from the applied nitrogen fluence and is of the order of 0.4 beryllium atoms per impinging nitrogen atom. (C) 2014 Elsevier B.V. All rights reserved.

[发布日期] 2014-12-01

[效力级别]  Proceedings Paper

[关键词] Plasma wall interaction;Sputtering;Erosion;Beryllium