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Patrick O'Shea
Vice President for Research
Professor of Electrical
& Computer Engineering
Distinguished
Scholar Teacher
Affiliate
Appointments:
Institute
for Research in Electronics & Applied Physics
Department of Physics
Maryland
Nano Center
Maryland Energy Research
Center
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Land mail:
Division of Research Lee Hall
University
of Maryland
College
Park, MD 20742
Phone:
(301) 405-6499
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Patrick
G. O’Shea is Vice President for Research and Senior Research Officer of the University of Maryland, and Professor of Electrical & Computer Engineering. He holds affiliate appointments in Institute for Research in Electronics
& Applied Physics, Department of
Physics,
Maryland Nano Center, and Maryland Energy Research Center.
He
is a Fellow of the Institute
of Electrical and Electronic Engineers, a Fellow of the American
Physical Society, a Fellow of the American Association
for the Advancement of Science, and a University of
Maryland Distinguished Scholar-Teacher. Professor
O’Shea’s technical expertise lies in the field of
applied electromagnetics, nonlinear dynamics and particle accelerator
technology, and applications. He is also interested in history. Advice to young researchers: “If you do not work on important problems, you will not do important work.” You and Your Career by Richard Hamming |
O'Shea Group Projects
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Photo: Tim Koeth |
University of Maryland Electron Ring
Project - UMER Continuing A Space Charge
Odyssey The
nonlinear dynamics of electron swarms is important for several
applications, including high energy physics accelerators where we are
exploring space charge dominated beams for advanced accelerators; particle beam driven high energy density physics,
including, inertial fusion energy; applications to galactic dynamics; and
free-electron light sources.
The
group began studying space charge dominated beams (AKA intense beams) in the
1980s under the direction of Professor Martin
Reiser, who is now Professor Emeritus. UMER is the culmination of Prof. Reiser's dream of a dedicated facility for the study of
intense beam physics and engineering. |
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Photo: Chip Simons |
Free-Electron lasers: Creating coherent light where there is darkness since 1990. Regions of the spectrum were there is a need for brighter light include the x-ray (coherent x-ray probes for Nanoscale Science and Technology); UV and infrared radiation for industrial processing, and far infrared THz sources for biological probes. Prof. O'Shea began exploring the development of free-electron light sources and enabling technologies in 1990 at Los Alamos where he was project leader of the APEX Free-Electron Laser. This was the first photoinjector linear accelerator driven ultra-violet FEL. Photoinjectors use laser switched photoemitters to generate the bright beams required for certain kinds of FELs. Recently the research group has been working on several aspects of the generation of bright electron beams including: novel photocathodes, the dynamics of beams with space charge, and beam diagnostic probes, and FEL theory and simulation. Laboratory
for Photocathode Research
Review article: Free-Electron Lasers,
Science 8 June
2001, Vol. 292, page 1853 Review Article: Electron Sources for Accelerators,
Physics Today, February, 2008, page 44 |
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Selected Recent Publications: |
Emittance of a
field emission electron source, K. L. Jensen, P. G. O'Shea, D. W.
Feldman, and J. L. Shaw, J. Appl. Phys. 107, 014903 (2010) Terahertz laser
modulation of electron beams, J.G Neumann, R.B. Fiorito, P.G. O'Shea,
H. Loos, B. Sheehy, Y. Shen, Z. Wu, J. Appl. Phys. 105,
053304 (2009) Time-dependent
Phase Space Characterization of Intense Charged Particle Beams," Physical
Review Special Topics - Accelerators & Beams D. Stratakis,
R.A. Kishek, R.B. Fiorito, K. Tian, I. Haber, P.G.
O'Shea, M. Reiser, and J.C.T. Thangaraj,12, 020101 (2009). Aperture effects
and mismatch oscillations in an intense electron beam, J.R Harris, P.G.
O’Shea, Phys. Plasmas 15, 123106 (2008) Multicomponent measurements of the Jefferson Lab energy
recovery linac electron beam using optical
transition and diffraction radiation M.A. Holloway, R.B. Fiorito, A.G.
Shkvarunets, P. G. O’Shea, S.V. Benson, D. Douglas, P. Evtushenko, and K.
Jordan, Phys. Rev. ST Accel. Beams 11, 082801 (2008) Theory of photoemission from cesium antimonide
using an alpha-semiconductor model, K L Jensen, BL Jensen, EJ
Montgomery, DW Feldman, PG O'Shea, and NA Moody, J. Appl. Phys. 104, 044907 (2008) Electron emission contributions to dark current and its relation to
microscopic field enhancement and heating in accelerator structures,
K L. Jensen, Y. Y. Lau, D. W. Feldman and P. G. O’Shea, Phys. Rev. ST Accel. Beams 11, 081001 (2008) Application of a
general electron emission equation to surface nonuniformity
and current density variation KL Jensen, JJ Petillo, EJ
Montgomery, ZG Pan, DW Feldman PG
O'Shea, NA Moody, M. Cahay, JE Yater,
JL Shaw J. Vac. Sc. & Tech B, 26, 831 (2008) Negative transconductance in apertured electron guns, J. R. Harris and P. G
O'Shea, Journal of Applied Physics. 103, 113301 (2008) Time-Dependent Imaging of Space-Charge-Dominated Electron
Beams, K. Tian, R.A. Kishek, P.G. O'Shea,
R.B. Fiorito, D.W. Feldman, and M. Reiser, Physics of
Plasmas 15, 056707 (2008). Longitudinal density
modulation and energy conversion in intense beams J. R.
Harris, J. G. Neumann, K. Tian, and P. G. O’Shea,
Phys. Rev. E, 76 026402 (2007) Theoretical
model of the intrinsic emittance of a photocathode, K. L. Jensen P.
G. O'Shea, D. W. Feldman, and N. A. Moody, Applied Physics Letters. 89, 224103 (2006) A photoemission model for low
work function coated metal surfaces and its experimental validation, Kevin
L. Jensen, Donald W. Feldman, Nathan A. Moody, and Patrick G. O'Shea, J.
Appl. Phys. 99, 124905 (2006) Field-enhanced
photoemission from metals and coated materials, Kevin L. Jensen,
Donald W. Feldman, Nathan A. Moody, and Patrick G. O'Shea, Journal of
Vacuum Science & Technology B: Microelectronics and Nanometer Structures 863,
(2006) Fixed-Geometry RMS Envelope Matching of Electron Beams
from 'Zero' Current to Extreme Space-Charge, S. Bernal, H. Li,
R.A. Kishek, B. Quinn, M. Walter, M. Reiser, P.G. O'Shea, and C.K.
Allen, Physical Review ST - Accelerators & Beams
9, 064202 (2006). Tomography as a Diagnostic Tool for Phase Space Mapping of
Intense Particle Beams, D. Stratakis, R.A. Kishek, H. Li, S. Bernal, M. Walter, B. Quinn,
M. Reiser, and P.G. O'Shea, Physical
Review Special Topics - Accelerators & Beams 9, 112801 (2006).
Gridded
Electron Guns and Modulation of Intense Beams, J.R. Harris and P.G.
O'Shea, IEEE Transactions on Electron Devices 53(11), 2824-2829
(2006). Experimental
observations of longitudinal space-charge waves in intense electron beams,
K. Tian, Y. Zou, Y. Cui, I. Haber, R. A. Kishek, M. Reiser,
and P. G. O’Shea, Physical Review. ST Accel. Beams 9, 014201 (2006) Governing factors for production of photoemission-modulated
electron beams J. R. Harris, J. G. Neumann, and P. G. O'Shea, J.
Appl. Phys. 99, 093306 (2006) RMS envelope matching of electron beams
from “zero” current to extreme space charge in a fixed lattice of short
magnets, Bernal, H. Li, R. A. Kishek, B. Quinn, M. Walter, M. Reiser, P. G. O’Shea, and C. K. Allen. Phys. Rev.
ST Accel. Beams 9, 064202 (2006) Nonlinear Harmonic Generation in Free-Electron Lasers
with Helical Wigglers, H.P. Freund, P.G. O’Shea, S. Biedron, Physical Review
Letters, 94, 074802 (2005) Observation
of anomalous increase of longitudinal energy spread in a space-charge
dominated electron beam, Y. Zou, Y. Cui, M. Reiser, and P. G. O'Shea, Physical
Review Letters, 94,
134801 (2005) The quantum efficiency of dispenser photocathodes: Comparison of theory to experiment K. L. Jensen, D. W. Feldman and P.G. O’Shea, Applied Physics Letters. 85, 5448 (2004) |
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Vincit veritas |
"Restraint
in the pursuit of excellence is no virtue"
Last updated September 2011