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Title: Experimental gun brightness measurements on a 300 kV CFEG

Abstract

Effective use of the ANL 300kV CFEG/AAEM requires a knowledge of the probe current and size distribution during operation. In most cases this can be calculated once basic parameters of the system are experimentally determined. Central to this is a determination of the source brightness of the Cold Field Emission Gun (CFEG) under standard operating conditions of the instrument. For the last ten years most probe calculations of CFEG`s have been done assuming a brightness parameter of {beta}{approximately}1{times}10{sup 9} A/cm{sup 2}/sterad{sup 2} at 100 kV, while few if any experimental values have been reported at 300 kV. In order to determine {beta}, and thus characterize the source, the authors have measured the probe size, current and convergence angles on the ANL AAEM and from this calculated the effective brightness as a function of operating conditions. They compute d{sub g} = 0.92 nm and effective source brightness for the system of {beta} = 8.6{times}10{sup 8} A/cm{sup 2}/sterad. A value which is within experimental errors of the commonly used parameter at 100 kV, but is less than the expected value of {approximately}4{times}10{sup 9} A/cm{sup 2}/sterad.

Authors:
 [1];  [2]
  1. Argonne National Lab., IL (United States). Materials Science Div.
  2. Univ. of Illinois, Chicago, IL (United States). Research Resource Center
Publication Date:
Research Org.:
Argonne National Lab., IL (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
638236
Report Number(s):
ANL/MSD/CP-95599; CONF-980713-
ON: DE98057803; TRN: 98:007840
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: Microscopy and microanalysis 1998, Atlanta, GA (United States), 12-16 Jul 1998; Other Information: PBD: Jan 1998
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; ELECTRON GUNS; CALCULATION METHODS; ELECTRON PROBES; ELECTRON MICROPROBE ANALYSIS; BRIGHTNESS; SIZE

Citation Formats

Zaluzec, N J, and Nicholls, A. Experimental gun brightness measurements on a 300 kV CFEG. United States: N. p., 1998. Web.
Zaluzec, N J, & Nicholls, A. Experimental gun brightness measurements on a 300 kV CFEG. United States.
Zaluzec, N J, and Nicholls, A. Thu . "Experimental gun brightness measurements on a 300 kV CFEG". United States. https://www.osti.gov/servlets/purl/638236.
@article{osti_638236,
title = {Experimental gun brightness measurements on a 300 kV CFEG},
author = {Zaluzec, N J and Nicholls, A},
abstractNote = {Effective use of the ANL 300kV CFEG/AAEM requires a knowledge of the probe current and size distribution during operation. In most cases this can be calculated once basic parameters of the system are experimentally determined. Central to this is a determination of the source brightness of the Cold Field Emission Gun (CFEG) under standard operating conditions of the instrument. For the last ten years most probe calculations of CFEG`s have been done assuming a brightness parameter of {beta}{approximately}1{times}10{sup 9} A/cm{sup 2}/sterad{sup 2} at 100 kV, while few if any experimental values have been reported at 300 kV. In order to determine {beta}, and thus characterize the source, the authors have measured the probe size, current and convergence angles on the ANL AAEM and from this calculated the effective brightness as a function of operating conditions. They compute d{sub g} = 0.92 nm and effective source brightness for the system of {beta} = 8.6{times}10{sup 8} A/cm{sup 2}/sterad. A value which is within experimental errors of the commonly used parameter at 100 kV, but is less than the expected value of {approximately}4{times}10{sup 9} A/cm{sup 2}/sterad.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {1}
}

Conference:
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