Particle Accelerators
and their Applications
Rami A. Kishek
on behalf of the UMER team
Institute for Research in
Electronics & Applied Physics
University of Maryland, College Park, MD, USA
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Research sponsored by US DOE & DOD ONR
Institute for Research in
Electronics & Applied Physics
Research Focus:
Interdisciplinary research in engineering and the physical sciences with
emphasis on large and complex experiments. Faculty and students from
Electrical & Computer Engineering, Physics and Materials Science.
Specialties:
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Chaos and Nonlinear Dynamics
Space & Fusion Plasmas
Beam Physics
Microwaves and Electronics
Nanoscience and Engineering
Materials Processing
(using microwaves, plasmas, ion beams)
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Outline
1. What are Particle Accelerators?
2. Common Accelerator Applications
3. Research at Maryland
4. Opportunities for Students
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Do you know how your TV Works?
Anode
(A)
-Heat
-- Cathode --(K)
High
Voltage
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Phosphor
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Screen
Accelerator Schematic
(many km)
Source
Transport
Target
Accelerate
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CERN, LHC – The Largest Accelerator
Large Hadron Collider (LHC),
CERN, Geneva
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http://www.cern.ch/
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Accelerator Applications
Industry
Science Research
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Particle Physics
Nuclear Physics
Astrophysics
Probing material structure
Biosciences
Microscopy
Artifact dating
Light sources (includes X-ray)
Neutron sources
Lasers
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Ion implantation
Food Sterilization
Lithography
Nanotechnology
Accelerators
Medicine
• Imaging
• Isotope production
• Cancer Radiotherapy
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Energy Production
• Controlled nuclear fusion
Environment
• Radioactive waste treatment
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Accelerator-Driven Neutron Sources
Spallation Neutron Source,
Oak Ridge, TN
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• Transportation
• Electronics
• Manufacturing
• Environment
• Medicine
• Engineering
• Plastics
http://www.sns.gov/
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Energy: Controlled Fusion w/ Heavy Ion Beams
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http://hif.lbl.gov/
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Light Sources
Bend magnet radiation
Undulator radiation
Technology
Spectrum
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One Solution: Free Electron Lasers (FELs)
amplified
radiation
electron
beam
bunched
electron beam
input radiation
Radiated wavelength:
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λw
λ r ≈ 2 (1 + K 2w )
2γ
Normalized vector potential of undulator
Kw = 0.93 Brms (Tesla) λw (cm) ≈ order unity
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Free Electron Lasers illuminate the Nanoworld
LCLS, X-ray FEL, Stanford, CA
1.5 Å, femtosec
10-2 m
~ 2.5 nm
0.1 mm
100 μm
10-5 m
0.01 mm
10 μm
Infrared
10-4 m
1,000 nanometers =
1 micrometer (μm)
Visible
10-6 m
Gordon
Moore
Nanoworld
10-7 m
0.1 μm
100 nm
Ultraviolet
http://www-ssrl.slac.stanford.edu/lcls/
Microworld
The First Computer
DNA, Proteins
106 nanometers
=
Microwave
10-3 m
1 cm
10 mm
10-8 m
0.01 μm
10 nm
10-9 m
Soft x-ray
1 nanometer (nm)
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10-10
m
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0.1 nm
Medical Diagnosis and Treatment
Tomography
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Treatment of Cancer with
Protons or Heavy Ions
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http://www.nirs.go.jp/ENG/nirs.htm
Accelerators are complex machines
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Beam Dynamics
x
z
y•
e–
Paraxial assumption
vx, vy << vz
1. Randomness
2. Mutual Repulsion – Space Charge
Need to apply focusing – Magnets
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Space Charge Adds Complication
• Beam distribution changes
• Exotic Phenomena
– Waves and Fluctuations
– Halos
– Instabilities
• Quality degradation
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Requires Extensive Modeling & Simulation
• Problem:
Space charge force depends on beam distribution, which
constantly evolves in response to the forces
• Typical beam may contain 109 - 1012 particles
• Typical accelerator measured in km, while focusing
magnets vary on a scale of cm.
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Understanding Requires Detailed Knowledge
Beam patterns sensitive to initial velocity distribution!
Experiment (100 mA) (top) [Bernal]
1.0 cm
Q1
T Q2
Q3
Q4
WARP Simulation (below) [Kishek]
1.0 cm
K-V Distribution
Semi-Gaussian Distribution
Hollow-Velocity Distribution
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The University of Maryland Electron Ring
Use 10 keV electrons to
inexpensively model
space charge effects in
other accelerators
3.7 m
Energy
Energy Spread
Current Range
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rms Emittance
10 keV
20 eV
0.6-100 mA
Circulation time
Pulse length
Zero-Current Tune
200 ns
5-100 ns
7.6
0.2-3 μm
Depressed Tune
1.5 – 6.5
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UMER Magnets & Lattice
72 Quads
(~ 7.8 G/cm)
32 cm
36 Dipoles
(~ 15 G)
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UMER Multi-Turn: “Low-Current” Results
(Work in Progress)
Typical
BPM signals
for low current
060525 test2 : Beam Current Per Turn from BPM 2
8.
-4
6.
4.
1 mV/div
up to
125 turns
2.
500 ns/div
0.
0
50
100
time along pulse [ns]
Zero-current
Tune=7.3
Beam
Current
Estimated
Emittance*
Tune
Depression
Tune Shift
Injected
690 μA
5.6 μm
0.89
0.80
After 25 turns
300 μA
4.6 μm
0.94
0.45
*4rms, unnormalized
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S. Bernal, Proc. Advanced Accelerators Concepts Wkshp 2006.
Multi-Turn: More Intense Space Charge
p
Beam Current (mA)
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(Work in Progress)
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up to
60 turns
10
05
0
500
Zero-current
Tune=7.3
1000
Time [ns]
1500
Estimated
Emittance *
24 μm
Tune Depression
Injected
Beam
Current
18.6 mA
0.55
3.3
After 9 turns
3.6 mA
10-25 μm
0.72-0.87
2.0-0.9
*4rms, unnormalized
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Tune Shift
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M. Walter, Proc. Advanced Accelerators Concepts Wkshp 2006.
Opportunities for Graduate Students
Research Assistantships available
– Need strong academic record
– Good background in Electromagnetism
• Experiments
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Diagnostics
Electronics
Controls
Mechanical Skills
• Theory and Simulation
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Tomography: Characterization of Beams
Additional projections at different
angles add information to our image of
the phase space
Different Distribution
X’
WARP
X
Tomography
1 mrad
X
1 cm
1 mrad
X’
1 cm
X’
X’
X
X
WARP simulation Reconstructed by
hollow-velocity
tomography on
simulation results
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D. Stratakis, PRSTAB, to appear (2006).
Propagation of Density Perturbation on Beam
Beginning
20 mA thermal-emission beam current
20 mA photo-emission beam current
Current (A)
WARP
simulation
Z (m)
End
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Y. Huo, to be published
Space charge converts density perturbation
to an energy perturbation
Group 2 - initial beam current
10
-10
0
-10
-20
-20
-30
-30
current/mA
current/mA
Current/A
Group 1 - initial beam current
0
-40
-50
-40
-50
-60
-60
-70
-70
-80
-80
-90
-50
-90
0
50
100
150
-100
-50
200
0
50
time/ns
100
150
200
150
200
time/ns
Initial Current vs. Time
Group 3 - initial beam current
Group 4 - initial beam current
0
0
-10
-10
-20
-20
current/mA
current/mA
-30
-40
-50
-30
-40
-60
-50
-70
-80
-50
time/ns 0
0
50
100
100
time/ns
150
200
200
-60
-50
0
50
100
time/ns
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K. Tian, et al., PRSTAB 9, 014201 (2006).
ENEE 686 – Spring 2007
Charged Particle Dynamics
MW 12:30 – 1:45 PM
3 Credits!
Register Now!
Prof. Rami A. Kishek
301 405 5012
ramiak@umd.edu
This course introduces the basic dynamics of electron and ion beams.
Emphasis on theoretical treatment, with exposure to the latest computer
simulation techniques.
Prerequisites: Graduate-level Electromagnetism
Topics:
¾ Particle accelerator systems
¾ Phase space concepts
¾ Focusing and transport optics
¾ Acceleration Techniques
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¾Collective phenomena
¾Self-consistent theory of beams
¾Emittance growth and control
¾Radiation
¾Applications of Accelerators
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Visit Our Website for More Information
http://www.umer.umd.edu/
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I like to thank my colleagues …
University of Maryland Electron Ring (UMER) Team:
Patrick O’Shea
Martin Reiser
Rami Kishek
Irving Haber Brian
Beaudoin
Junior Scientists:
Santiago Bernal
Mark Walter
BryanQuinn
Bryan
Quinn
Brian Beaudoin
Graduate:
Gang Bai
Kai Tian
Donald
Dave
C Papadopoulos
Feldman
Sutter
Diktys Stratakis
Charles Tobin
Former:
Yun Zou
Jonathan
Neumann
Diktys
Stratakis
Yupeng
Cui
Hui Li
Yijie Huo
Santiago John
Martin
Harris
Renee Feldman
Don Feldman
Ralph Fiorito
Irving
Charles
Kai Tian
Henry FreundGang Bai
Haber
Tobin
Bernal
Terry F. Godlove
A. Shkvarunets
Mike Holloway
Kevin Jensen
Dave Gillingham
Mark
Christos
Patrick David
RamiDemske
Renee
Walter
Papadopoulos O’Shea
Kishek
Feldman
Nathan Moody
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Terry
Godlove
Reiser
Ralph
Fiorito
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