Title: Secondary electron emission from plasma-generated nanostructured tungsten fuzz

Abstract

Recently, several researchers (e.g., Q. Yang, Y.-W. You, L. Liu, H. Fan, W. Ni, D. Liu, C. S. Liu, G. Benstetter, and Y. Wang, Scientific Reports 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 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 suchmore » as tungsten fuzz can be desirable for improved performance of many plasma devices.:7px« less

Authors:

Patino, M.  ^[1];

• Search DOE PAGES for author "Patino, M."
• Search DOE PAGES for ORCID "0000-0002-2622-7110"

Raitses, Y.  ^[2];

• Search DOE PAGES for author "Raitses, Y."
• Search DOE PAGES for ORCID "0000-0002-9382-9963"

Wirz, R.  ^[3]

• Search DOE PAGES for author "Wirz, R."
• Search DOE PAGES for ORCID "0000-0001-5309-3659"

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+ Show Author Affiliations

1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Los Angeles, CA (United States)
2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
3. Univ. of California, Los Angeles, CA (United States)

Publication Date:

Mon Nov 14 00:00:00 EST 2016

Research Org.:

Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1335459

Alternate Identifier(s):

OSTI ID: 1332367

Grant/Contract Number:  

AC02-09CH11466; AF9550-09-1-0695; FA9550-11-1-0282; FA9550-14-1-0053; FA9550-14-10317

Resource Type:

Accepted Manuscript

Journal Name:

Applied Physics Letters

Additional Journal Information:

Journal Volume: 109; Journal Issue: 20; Journal ID: ISSN 0003-6951

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Secondary emission; Tungsten; X-ray photoelectron spectroscopy; Sputtering; Plasma