Secondary electron emission from plasma-generated nanostructured tungsten fuzz
Abstract
Recently, several researchers [e.g., Yang et al., Sci. Rep. 5, 10959 (2015)] have shown that tungsten fuzz can grow on a hot tungsten surface under bombardment by energetic helium ions in different plasma discharges and applications, including magnetic fusion devices with plasma facing tungsten components. This work reports the direct measurements of the total effective secondary electron emission (SEE) from tungsten fuzz. Using dedicated material surface diagnostics and in-situ characterization, we find two important results: (1) SEE values for tungsten fuzz are 40%–63% lower than for smooth tungsten and (2) the SEE values for tungsten fuzz are independent of the angle of the incident electron. The reduction in SEE from tungsten fuzz is most pronounced at high incident angles, which has important implications for many plasma devices since in a negative-going sheath the potential structure leads to relatively high incident angles for the electrons at the plasma confining walls. Overall, low SEE will create a relatively higher sheath potential difference that reduces plasma electron energy loss to the confining wall. Thus, the presence or self-generation in a plasma of a low SEE surface such as tungsten fuzz can be desirable for improved performance of many plasma devices.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 14, 2016
- Source ID
- 10.1063/1.4967830
Entities
People
- M. Patino
- Richard E. Wirz
- Yevgeny Raitses
Organizations
- Air Force Office of Scientific Research
- Office of Science
- Princeton Plasma Physics Laboratory
- United States Department of Energy
- University of California