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Title: An in-situ spectroscopic erosion yield measurement with applications to sputtering and surface morphology alterations

Technical Report ·
DOI:https://doi.org/10.2172/6933215· OSTI ID:6933215

An in-situ spectroscopic erosion yield measurement is developed and used to monitor material surface erosion during bombardment by a plasma. The experiments are performed in a plasma that has the characteristics of a fusion tokamak boundary plasma but the technique is applicable to many processes where plasma erosion is important. Erosion yield of materials bombarded in a high flux (up to 10/sup 18/ion/cm/sup 2//s) plasma environment has been previously studied using weight loss measurements. In the present study, the sputtered flux from a material is monitored by the line emission intensities of atoms eroded from the surface. The line intensities can be used to infer erosion yields after proper calibration. The method agrees well with results from weight loss measurements. Earlier work established that the material surface structure can substantially influence the erosion yield. When a change of surface morphology (e.g. cone formation) occurs, weight loss methods cannot be used to determine the erosion yield. However, the in-situ erosion measurement is suitable and is used to investigate the relation between the on-set of morphology changes and alternations in erosion yield during plasma bombardment. Experiments are reported for copper, as an example of pure material, and stainless steel, as a example of an alloy system. The formation of surface cones is observed only when both the sample temperature is above a critical value and surface impurities exist. If the source of impurities is removed, or the sample temperature is lowered below the critical values, a surface rough with cones will be returned to smooth state. 20 refs., 10 figs.

Research Organization:
California Univ., Los Angeles (USA). Dept. of Mechanical, Aerospace and Nuclear Engineering
DOE Contract Number:
AS03-84ER52104
OSTI ID:
6933215
Report Number(s):
UCLA/PPG-1167; ON: DE88014085
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English