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┴g˙st Valfells

Publications

JOURNAL ARTICLES

A. Singh, A. Valfells,  M.J. Kolander, V.L. Granatstein, “Improvements in depressed collector performance by modifications to electrode geometry vis-a-vis trajectories of backscattered electrons”, IEEE Trans. Plasma Sci., 32, 1267 (2004).

S. Bernal, B. Beaudoin, Y. Cui, M. Glanzer, T. F. Godlove, J. Harris, M. Holloway, I. Haber, R.A. Kishek, W-T. Lee, H. Li, D. Lamb, B. Quinn, M. Qurius, M. Reiser, A. Valfells, M. Virgo, M. Walter, M. Wilson, R. Yun, Y. Zou, and P. G. O'Shea, “Intense Beam Transport Experiments in a Multi-Bend System at the University of Maryland Electron Ring (UMER)”, Nucl. Inst. and Meth. A, 519, 380 (2004).

Y. Cui, Y. Zou, A. Valfells, M. Walter, I. Haber, R.A. Kishek, S. Bernal, M. Reiser, and P.G. O'Shea, "Design and Operation of a Retarding Field Energy Analyzer with Variable Focusing for Space-Charge Dominated Electron Beams," Review of Scientific Instruments, 75, 2736 (2004).

C,M. Celata, et al., “Progress in Heavy Ion Fusion Research”, Phys. Plasmas, 10, 2064 (2003).

P.G. O’Shea, R.A. Kishek, M. Reiser, B. Beaudoin, S. Bernal, Y. Cui, A. Diep, D. Feldman, M. Glanzer, T.F. Godlove, I. Haber, J. Harris, H. Li, J. Neumann, B. Quinn, M. Quirus, M. Snowel, A. Valfells, M. Virgo, M. Walter, R. Yun, Y. Zou, “Experiments with Space-Charge Dominated Beams for Heavy Ion Fusion Applications”, Laser and Particle Beams, Proc. 14th International Symposium on Heavy Ion Inertial Fusion, May 2002, Moscow, Russia (Sam■ykkt til birtingar 2002).

Y. Zou, Y. Cui, V.Yun, A. Valfells, R.A. Kishek, S. Bernal, I. Haber, M. Reiser, P.G. O’Shea, J.G. Wang, “Compact High-Resolution Retarding Field Analyzer for Space-Charge Dominated Electron Beams” Phys. Rev ST Accel. Beams, 5, 72801 (2002).

A. Valfells, A. Singh, M.J. Kolander, V.L. Granatstein, “Advancements in Codes for Computer Aided Design of Depressed Collectors and Tracing of Backscattered Electrons-Part II: Improvements in the Modeling of the Physics of Secondary Electron Emission and Backscattering”, IEEE Trans. Plasma Sci., 30, 1271 (2002).

A. Singh, A. Valfells, C.B. Robey, J. Goldstein, M.J. Kolander, V.L. Granatstein, “Advancements in Codes for Computer Aided Design of Depressed Collectors and Tracing of Backscattered Electrons-Part I: Optimization of Depressed Potentials and Tracking of Multiple Orders of Backscatter”, IEEE Trans. Plasma Sci., 30, 1265 (2002).

A. Valfells, D.W. Feldman, M. Virgo, P.G. O’Shea, “Effects of Pulse-Length and Emitter Area on Virtual Cathode Formation in Electron Guns”, Phys. Plasmas, 9, 2377 (2002).

R.B. Anderson, W.D. Getty, M.L. Brake, Y.Y. Lau, R.M. Gilgenbach, A. Valfells, “Multipactor Experiment on a Dielectric Surface”, Rev. Sci. Instr., 72, 3095 (2001).

A. Valfells, J.P. Verboncoeur, Y.Y. Lau, “Space-Charge Effects on Multipactor on a Dielectric”, IEEE Trans. Plasma Sci., 28, 529 (2000).

A. Valfells, L.K. Ang, Y.Y. Lau, R.M. Gilgenbach, “Effects of an External Magnetic Field, and of Oblique Radio-Frequency Electric Fields on Multipactor Discharge on a Dielectric”, Phys. Plasmas, 7, 750 (2000).

R.A. Kishek, Y.Y. Lau, L.K. Ang, A. Valfells, R.M. Gilgenbach, “Multipactor Discharges on Metals and Dielectrics: Historical Review and Recent Theories”, Phys. Plasmas, 5, 2120 (1998).

A. Valfells, R. A. Kishek, Y.Y. Lau, “Frequency Response of Multipactor Discharge”, Phys. Plasmas, 5, 300 (1998).

J.W. Luginsland, A. Valfells, Y.Y. Lau, “Effects of a Series Resistor on Electron Emission from a Field Emitter”, Appl. Phys. Lett., 69, 2770 (1996).

 

INVITED PAPERS

A. Valfells, D.W. Feldman, Y.Y. Lau, M. Virgo, P.G. O’Shea, “Three Dimensional Effects on Virtual CAthode Formation in Electron Guns”, 43rd Annual Meeting of the Division of Plasma Physics of the American Physical Society, November 2001.

A. Valfells, A. Singh, M. Kolander, V. Granatstein, “Improvements in Modeling of Backscatter of Electrons in a Code for Tracing their Trajectories”, IRMMW 2001, Toulouse, France, September 2001.

 

REPORTS

┴g˙st Valfells, “VistvŠnt eldsneyti: M÷guleikar ═slendinga til ■ess a­ draga ˙r notkun jar­efnaeldsneytis”, ReykjavÝk: Orkustofnun 2005.

 

CONFERENCE PROCEEDINGS

A. Valfells, "Practical pathways toward a 'hydrogen economy' -a view from Iceland", Hydrogen Fuel Cells and Alternatives in the Transport Sector: Issues for Developing Countries; United Nations University International Conference, Maastricht, The Netherlands, 7-9 November 2005.

A. Valfells, I.B. Fridleifsson, T. Helgason, J. Ingimarsson, F. Sophusson, G. Thoroddsson, “Sustainable Generation and Utilization of Energy –The Case of Iceland”, 19th World Energy Congress, Sydney, Australia, September 5-9 2004, 13 bls.

A. Singh, A. Valfells, M. Kolander, and V.L. Granatstein, “Computer Aided Design of Depressed Collectors”, AIP Conf. Proc. 691, 127 (2003)

J. Harris, A. Valfells, B. Quinn, S. Bernal, I. Haber, M. Walter, A. Diep, M. Reiser, and P. G. O'Shea, “Initial Studies of Longitudinal Beam Dynamics on UMER”, Proceedings of the 2003 IEEE Particle Accelerator Conference, Portland OR, ed. J. Chew, P. Lucas, S. Webber, IEEE Cat. No. 03CH37423C, 2312 (2003).

M. Walter, S. Bernal, A. Diep, M. Glanzer, I. Haber, J. Harris, R.A. Kishek, D. Lamb, W. Lee, H. Li, B. Quinn, M. Qurius, A. Valfells, M. Reiser, and P.G. O'Shea, “Alignment of Components at the University of Maryland Electron Ring” , Proceedings of the 2003 IEEE Particle Accelerator Conference, Portland OR, ed. J. Chew, P. Lucas, S. Webber, IEEE Cat. No. 03CH37423C, 2577 (2003)

M. Walter, D. Lamb, S. Bernal, I. Haber, R.A. Kishek, H. Li, B. Quinn, M. Snowel, A. Valfells, M. Reiser, and P.G. O'Shea, “Time Resolved Emittance MeasUreMent in the University of Maryland Electron Ring”,  Proceedings of the 2003 IEEE Particle Accelerator Conference, Portland OR, ed. J. Chew, P. Lucas, S. Webber, IEEE Cat. No. 03CH37423C, 2574 (2003).

M. Walter, S. Bernal, T. Godlove, I. Haber, R.A. Kishek, H. Li, B. Quinn, A. Valfells, Y. Zou, M. Reiser, and P.G. O'Shea, “Electro-Mechanical Design for Injection in the University of Maryland Electron Ring”, Proceedings of the 2003 IEEE Particle Accelerator Conference, Portland OR, ed. J. Chew, P. Lucas, S. Webber, IEEE Cat. No. 03CH37423C, 1673 (2003).

S. Bernal, B. Beaudoin, Y. Cui, A. Diep, T. Godlove, I. Haber, J. Harris, R.A. Kishek, D. Lamb, H. Li, M. Glanzer, B. Quinn, M. Reiser, A. Valfells, M. Walter, M. Wilson, R. Yun, Y. Zou, and P.G. O'Shea, “Beam Transport Experiments over a Half Turn at the University of Maryland Electron Ring”, Proceedings of the 2003 IEEE Particle Accelerator Conference, Portland OR, ed. J. Chew, P. Lucas, S. Webber, IEEE Cat. No. 03CH37423C, 426 (2003).

Y. Cui, Y. Zou, I. Haber, R. Kishek, A. Valfells, M. Reiser, and P.G. O'Shea, “Experimental Study of Beam Energy Spread in the Space-Charge Dominated Beams”, Proceedings of the 2003 IEEE Particle Accelerator Conference, Portland OR, ed. J. Chew, P. Lucas, S. Webber, IEEE Cat. No. 03CH37423C, 3156 (2003).

P.G. O'Shea, B. Beaudoin, S. Bernal, Y. Cui, A. Diep, D. Feldman, M. Glanzer, T.F. Godlove, I. Haber, J. Harris, M. Holloway, D. Lamb, R.A. Kishek, H. Li, W. Lee, S. Martin, J. Neumann, B. Quinn, P.G O'Shea, M. Qurius, M. Reiser, M. Snowel, A. Valfells, M. Virgo, M. Walter, R. Yun, and Y. Zou, "Intense Beam Experiments at the University of Maryland Electron Ring," Proceedings of the Workshop on Advanced Accelerator Concepts, Mandalay Beach, Oxnard, CA, June 2002 (2002).

Y. Cui, Y. Zou, R.A. Kishek, and A. Valfells, "New Energy Analyzer Design and Preliminary Study on the Space-Charge Effect in the Energy Analyzer," Proceedings of the Workshop on Advanced Accelerator Concepts, Mandalay Beach, Oxnard, CA, June 2002 (2002).

R.A. Kishek, P.G. O'Shea, M. Reiser, B. Beaudoin, S. Bernal, Y. Cui, A. Diep, D. Feldman, M. Glanzer, T. F. Godlove, I. Haber, J. Harris, H. Li, J. Neumann, B. Quinn, M. Qurius, M. Snowel, A. Valfells, M. Virgo, M. Walter, R. Yun, and Y. Zou, "Intense Beam Experiments at the University of Maryland Electron Ring (UMER)," 20th ICFA Advanced Beam Dynamics Workshop on High Intensity & High Brightness Hadron Beams, Fermilab, Batavia, IL, April 2002, ed., W. Chou, Y. Mori, D. Neuffer, and J. Ostiguy, (New York: AIP Press 642, 2002), p. 319.

A. Valfells, S. Bernal, Y.P. Cui, R.A. Kishek, P.G. O'Shea, B. Quinn, M. Reiser, M. Virgo, V. Yun, and M. Nishiura, “Energy Analyzer Experiments for the University of Maryland Electron Ring”, Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, ed. P. Lucas and S. Weber, IEEE Cat. No. 01CH37268, 3582 (2001).

D.W. Feldman, A. Valfells, J. Neumann, J. Harris, B. Beaudoin, and P.G. O'Shea, “Combined Thermionic and Photoelectric Emission from Dispenser Cathodes”, Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, ed. P. Lucas and S. Weber, IEEE Cat. No. 01CH372681, 2132 (2001).

I. Haber, S. Bernal, R.A Kishek, P.G. O'Shea, M. Reiser, A. Valfells, and D.P. Grote, “Computer Simulation of the UMER Electron Gun”, Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, ed. P. Lucas and S. Weber, IEEE Cat. No. 01CH37268, 2952 (2001).

P.G. O'Shea, B. Beaudoin, S. Bernal, Y.P. Cui, D.W. Feldman, M. Glanzer, T.F. Godlove, J. Harris, M. Holland, R.A. Kishek, H. Li, B. Quinn, N. Rahimi, M. Reiser, A. Valfells, M. Virgo, M. Walter, R. Yun, V. Yun, D. Kehne, and I. Haber, “The University of Maryland Electron Ring”, Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, ed. P. Lucas and S. Weber, IEEE Cat. No. 01CH37268, 159 (2001).

S. Bernal, H. Li, M. Virgo, S.P. Kwon, M. Holland, R.A. Kishek, A. Valfells, T. Godlove, P.G. O'Shea, M. Reiser and V. Yun, and D. Kehne, “Beam Test of the 10keV Injector for the University of Maryland Electron Ring (UMER)”, Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, ed. P. Lucas and S. Weber, IEEE Cat. No. 01CH37268, 2129 (2001).

Y. Cui, S. Bernal, R.A. Kishek, P.G. O'Shea, N. Rahimi, M. Reiser, A. Valfells, and V. Yun, “Design Studies for an Experiment to Measure Energy Spread Evolution Through a Solenoidal Focusing System”, Proceedings of the 2001 Particle Accelerator Conference, Chicago, IL, ed. P. Lucas and S. Weber, IEEE Cat. No. 01CH37268, 2976 (2001).

A. Valfells, J.P. Verboncoeur, Y.Y. Lau, R.B. Anderson, R.M. Gilgenbach, " Space charge effects on multipactor on dielectric”, Proc. SPIE Vol. 4031, p. 65-74, Intense Microwave Pulses VII, Howard E. Brandt; Ed.

 

CONFERENCE TALKS AND POSTERS (ABSTRACTS ONLY)

┴. Valfells, et al., “Space charge studies on the University of Maryland Electron Ring”, ICFA Beam Dynamics Mini-Workshop on Space Charge Simulation, Trinity College, Oxford, April 2-4 2003.

S. Bernal, B. Beaudoin, Y. Cui, M. Glanzer, T. F. Godlove, J. Harris, M. Holloway, I. Haber, R.A. Kishek, W-T. Lee, H. Li, D. Lamb, B. Quinn, M. Quirus, M. Reiser, A. Valfells, M. Walter, M. Wilson, R. Yun, Y. Zou, P.G. O’Shea, “Intense Beam Transport Experiments in a Multi-Bend System at the University of Maryland Electron Ring (UMER)”, ”, 44th Annual Meeting of the Division of Plasma Physics of the American Physical Society, November 2002.

P.G. O’Shea, B.Beaudoin,S. Bernal, Y. Cui, A. Diep, D. Feldman, M. Glanzer, T.F. Godlove, I. Haber,J. Harris, R.A. Kishek, H. Li, J. Neumann, B. Quinn, M. Quirus, M. Reiser, M. Snowel, A. Valfells, M. Virgo, M. Walter, R. Yun, Y. Zou, “Intense Beam Experiments on the University of Maryland Electron Ring (UMER)”, Proc. LINAC  2002, Gyeongju, Korea, August 2002.

R.A. Kishek, S. Bernal, Y. Cui, D. Feldman, T.F. Godlove, I. Haber, H. Li, P.G. O’Shea, B.Quinn, M. Reiser, A. Valfells, M. Virgo, M. Walter, Y. Zou, “Simulations of Intense Beam Experiments at the University of Maryland”, Proc. LINAC  2002, Gyeongju, Korea, August 2002.

R.A. Kishek, S. Bernal, Y. Cui, D. Feldman, T.F. Godlove, I. Haber, H. Li, P.G. O’Shea, B.Quinn, M. Reiser, A. Valfells, M. Virgo, M. Walter, Y. Zou, “Scaled Experiments with Electrons at the University of Maryland”, Snowmass Fusion Summer Study, Snowmass, Colorado, July 2002.

P.G. O’Shea, S. Bernal, Y. Cui, D. Feldman, M. Glanzer, T. Godlove, J. Harris, I. Haber, H. Li, R.A. Kishek, B. Quinn, M. Reiser, A. Valfells, M. Virgo, M. Walter, M. Wilson, R. Yun, “Experimental Studies of Space-Charge Dominated Beams for Heavy Ion Inertial Fusion (HIF)”, Innovative Confinement Concepts Workshop (ICC2002), Adelphi, Maryland, January 2002.
 
L.K. Ang, A. Valfells, Y.Y. Lau, R.M. Gilgenbach, “Effects of Oblique Magnetic and Electric Fields on Dielectric Multipactor Discharge”, 1999 IEEE International Conference on Plasma Science.

A. Valfells, L. K. Ang, Y. Y. Lau, R. M. Gilgenbach, R. A. Kishek, J. Verboncoeur, A. Neuber, H. Krompholz, and L. L. Hatfield, “A Theory of RF Window Failure”, 1999 IEEE International Conference on Plasma Science.

A. Valfells, L. K. Ang, Y. Y. Lau, R. M. Gilgenbach, R. A. Kishek, J. Verboncoeur, A. Neuber, H. Krompholz, and L. L. Hatfield, “A Theory of RF Window Failure”, 40th Annual Meeting of the Division of Plasma Physics of the American Physical Society, November 1998.

Y.Y. Lau, R.A. Kishek, L.K. Ang, R.M. Gilgenbach, A. Valfells, “Multipactor Discharge on a Dielectric”, 1998 IEEE International Conference on Plasma Science.

A. Valfells, R. Kishek, Y.Y. Lau, R.M. Gilgenbach, “Suppression of Multipactor Discharge by Use of an Auxiliary RF Signal”, 39th Annual Meeting of the Division of Plasma Physics of the American Physical Society, November 1997.

A. Valfells, R.A. Kishek, Y.Y. Lau, R.M. Gilgenbach, “Frequency Response in Multipactor Discharge”, 1997 IEEE International Conference on Plasma Science.

A. Valfells, R.A. Kishek, Y.Y. Lau, R.M. Gilgenbach, “Frequency Response in Multipactor Discharge”, 38th Annual Meeting of the Division of Plasma Physics of the American Physical Society, November 1996.

Y.Y. Lau, J.W. Luginsland, A. Valfells, “Effects of a Base Resistor on Electron Emission from a Field Emitter”, 38th Annual Meeting of the Division of Plasma Physics of the American Physical Society, November 1996.

J.W. Luginsland, A. Valfells, Y.Y. Lau, “Effects of a Base Resistor on Electron Emission from a Field Emitter”, 1996 IEEE International Conference on Plasma Science.