Tungsten 'fuzz' growth re-examined: the dependence on ion fluence in non-erosive and erosive helium plasma
Tungsten 'fuzz' growth re-examined: the dependence on ion fluence in non-erosive and erosive helium plasma
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DOI：
10.1088/0029-5515/55/9/093033
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发表时间：
2015-09-01
期刊：
影响因子：
3.3
通讯作者：
Bradley, J. W.
中科院分区：
文献类型：
--
作者：
Petty, T. J.;Baldwin, M. J.;Bradley, J. W.
在低能量He离子冲击（50-80）eV下，在1000-1140 K下，在非变化氦（He）等离子体暴露条件下，测量了钨绒毛层的厚度x，覆盖4个离子影响量级Phi (10(24)-10（28)m(-2)）和Gamma (10(19)-10(23) m（-2) s(-1)）。获得的数据与先前公布的类似生长条件的数据相补充，并进行集体分析。新的分析允许快速的高通量增长与通常观察到的较低通量的较慢增长相协调。结果表明，固定t（1/2）时间依赖性是确定层厚的更一般表达式的特殊情况，x(Phi) = (C(Phi - Phi(0)))(1/2)，这取决于Phi，培养通量Phi(0)，生长常数C = 2.36(-0.56)(+1.54) x 10(-38) m(4)，这与温度有关。在观察绒毛表面形态开始之前必须超过的孵育通量确定为Phi(0) = 2.5(-1.0)(+1.5) x10(24) m（-2）。在以侵蚀常数epsilon（fuzz）为特征的模糊生长-侵蚀机制中，它与溅射产量成正比，通过用Lambert W函数解决先前工作的生长-侵蚀平衡问题，找到了x（Phi）的解析解。从解中得到了简单的极限表达式，用于确定平衡通量和绒毛厚度；这种预测与文献中先前的模糊生长-侵蚀平衡结果很好地一致。
The thickness x, of tungsten fuzz layers are measured for non-varying helium (He) plasma exposure conditions spanning four orders of ion fluence Phi (10(24)-10(28)m(-2)) and flux Gamma (10(19)-10(23) m(-2) s(-1)), at 1000-1140 K under low energy He ion impact (50-80) eV. The data obtained are complemented by previously published data of similar growth conditions, and collectively analysed. The new analysis allows for the reconciliation of fast high flux growth with commonly observed slower growth at lower flux. It is demonstrated that the standing t(1/2) time dependence is a special case of a more general expression for determining the layer thickness, x(Phi) = (C(Phi - Phi(0)))(1/2), that depends on Phi, an incubation fluence Phi(0), and the growth constant C = 2.36(-0.56)(+1.54) x 10(-38) m(4) , which is temperature dependent. The incubation fluence, which must be exceeded before the observation on the onset of fuzz surface morphology is determined to be Phi(0) = 2.5(-1.0)(+1.5) x10(24) m(-2). In fuzz growth-erosion regimes, characterized by an erosion constant epsilon(fuzz), that is proportional to the sputter yield, an analytic solution for x(Phi) has been found, by solving the growth-erosion equilibria problem of prior work with the Lambert W function. Simple limit expressions follow from the solution for determining the equilibrium fluence and fuzz thickness; the predictions of such being in good agreement with previous fuzz growth-erosion equilibria results in the literature.