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The Challenges of Low-Energy Secondary Electron Emission Measurement

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The Challenges of Low-Energy Secondary Electron Emission Measurement Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 11-2019 The Challenges of Low-Energy Secondary Electron Emission Measurement Matthew J. Vincie Follow this and additional works at: https://scholar.afit.edu/etd Part of the Electromagnetics and Photonics Commons Recommended Citation Vincie, Matthew J., "The Challenges of Low-Energy Secondary Electron Emission Measurement" (2019). Theses and Dissertations. 3151. https://scholar.afit.edu/etd/3151 This Dissertation is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. THE CHALLENGES OF LOW-ENERGY SECONDARY ELECTRON EMISSION MEASUREMENT DISSERTATION Matthew J. Vincie, Captain, USAF AFIT-ENG-DS-19-D-007 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. The views expressed in this prospectus are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENG-DS-19-D-007 THE CHALLENGES OF LOW-ENERGY SECONDARY ELECTRON EMISSION MEASUREMENT DISSERTATION Presented to the Faculty Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Matthew J. Vincie, BSEE, MSEE Captain, USAF November 2019 DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENG-DS-19-D-007 THE CHALLENGES OF LOW-ENERGY SECONDARY ELECTRON EMISSION MEASUREMENT DISSERTATION Matthew J. Vincie, B.S.E.E., M.S.E.E. Captain, USAF Committee Membership: Tod V. Laurvick, PhD Chair Hengky Chandrahalim, PhD Member Richard G. Cobb, PhD Member ADEDEJI B. BADIRU, PhD Dean, Graduate School of Engineering and Management AFIT-ENG-DS-19-D-007 Abstract The phenomena known as secondary electron emission was discovered over a century ago. Yet, it remains very difficult to model accurately due to the limited availability of reliable experimental data. With the growing use of computer simulations in hardware development, the need for accurate models has increased. This research focused on determining what factors may be causing measurement discrepancies and methods for increasing the accuracy of measurements. It was found that several assumptions are commonly invoked when these measurements are performed that may not always be consistent with reality. The violation of these assumptions leads to measurement bias that is contingent upon the apparatus and the voltages used during the measurement. This research showed that secondary electron yield measurements are sensitive to changes in the apparatus geometry, the current level, and the electron gun settings. New techniques, hardware, and models were developed in order facilitate greater measurement repeatability and accuracy. iv AFIT-ENG-DS-19-D-007 Ut Prosim v Acknowledgments This research presented many challenges which could not have been overcome without the contributions of many. I will forever be grateful to those that aided in my success. To Dr. Tod Laurvick, for always taking the time to listen to me, offering advice, and helping with software, contracting, and infrastructure issues. Thank you for your mentorship. To my committee members, Dr. Richard Cobb and Dr. Hengky Chandrahalim, for your support and feedback throughout my research. To Dr. James Sattler, for the procurement and installation of the secondary electron emission measurement apparatus used in this research. To Mr. Brian Crabtree and the machinists of the AFIT Model Fabrication Shop, for fabricating the parts used in this research and providing advice throughout my research. To Mr. Adam Fritzche, for your assistance with test equipment calibration and setup. To Ms. Angela Hayden, for your assistance with contracting and test equipment. To Mr. Richard Johnston, for your advice and assistance in sputtering gold on the fasteners of the modified sample puck. To Mr. Michael Hill, for your help in procuring the materials necessary to complete this research. To Mr. Greg Smith, for your support in the operation of the ultrahigh vacuum chamber used in this research. To the staff of the Department of Electrical and Computer Engineering, for assistance with travel, finance, and academic requirements. To my classmates, for all your support and humor throughout the past three years. vi To my daughter, for the love and joy you have brought to my life. To my wife, for your continual love, faithful support, and sacrifice. I could not have achieved this without you. Matthew J. Vincie vii Table of Contents Page I. Introduction ..................................................................................................................1 1.1 Research Goal ......................................................................................................3 1.2 Research Objectives ............................................................................................5 1.3 Chapter Outline ...................................................................................................6 1.4 Summary .............................................................................................................7 II. Literature Review .........................................................................................................8 2.1 Historical Overview ............................................................................................8 2.1.1 SEE Discovery ......................................................................................... 8 2.1.2 Classification of Secondaries ................................................................... 9 2.1.3 First Device to Harness SEE .................................................................. 11 2.1.4 Auger Electrons ...................................................................................... 12 2.1.5 Electron Diffraction................................................................................ 13 2.1.6 Vacuum Tube Distortion ........................................................................ 14 2.1.7 Multipactor Discovery............................................................................ 15 2.1.8 Multipactor Semi-empirical Modeling ................................................... 18 2.1.9 Multipactor Simulation .......................................................................... 21 2.1.10 SEE Measurement Difficulties ............................................................... 23 2.1.11 Summary of History ............................................................................... 26 2.2 Secondary Electron Yield ..................................................................................27 2.2.1 Measurement Techniques ....................................................................... 29 2.2.2 Application of Potential Bias ................................................................. 30 2.2.3 The Universal Curve .............................................................................. 36 2.2.4 Material Dependency ............................................................................. 38 2.2.5 Temperature Effects ............................................................................... 39 2.2.6 Surface Effects ....................................................................................... 40 2.2.7 Angle of Incidence Effects ..................................................................... 41 2.2.8 Effects of Primary Current Level ........................................................... 44 2.2.9 Models .................................................................................................... 44 2.2.10 Mitigation ............................................................................................... 48 2.3 Secondary Electron Energy Spectrum ...............................................................51 2.3.1 Measurement Techniques ....................................................................... 53 2.3.2 Models .................................................................................................... 61 2.4 Angular Distribution of Secondaries .................................................................63 2.4.1 Measurement Techniques ....................................................................... 68 2.4.2 Material Dependence.............................................................................. 71 2.4.3 Models .................................................................................................... 73 2.5 Multipactor Simulation Software ......................................................................74 2.6 The Challenges to Accurate Measurement ........................................................77 2.6.1 Assumption 1.......................................................................................... 77 2.6.2 Assumption 2.......................................................................................... 79 viii 2.6.3 Assumption 3.........................................................................................
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