HIF Research on the University of Maryland Electron Ring (UMER)

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HIF Research on the University of Maryland
Electron Ring (UMER)
Rami A. Kishek on behalf of UMER collaboration
Institute for Research in Electronics Applied
PhysicsUniversity of Maryland, College Park, MD
Research sponsored by US Department of Energy
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We Thank
University of Maryland Electron Ring (UMER) Team University of Maryland Electron Ring (UMER) Team University of Maryland Electron Ring (UMER) Team University of Maryland Electron Ring (UMER) Team University of Maryland Electron Ring (UMER) Team
Patrick OShea Martin Reiser Irving Haber Rami Kishek Junior Scientists Santiago Bernal Mark Walter Yun Zou Bryan Quinn Graduate Yupeng Cui Hui Li John Harris Yijie Huo Gang Bai Kai Tian Undergraduate D. Lamb W-T. Lee A. Gregory M. Holloway W. Tze Undergraduate D. Lamb W-T. Lee A. Gregory M. Holloway W. Tze
Terry F. Godlove Don Feldman Renee Feldman Junior Scientists Santiago Bernal Mark Walter Yun Zou Bryan Quinn Graduate Yupeng Cui Hui Li John Harris Yijie Huo Gang Bai Kai Tian Undergraduate D. Lamb W-T. Lee A. Gregory M. Holloway W. Tze Undergraduate D. Lamb W-T. Lee A. Gregory M. Holloway W. Tze

Virtual National Lab for Heavy Ion Fusion (also provided WARP) Alex Friedman Dave Grote Jean-Luc Vay Christine Celata Steve Lund John Barnard
NIU Court Bohn Ioannis Sideris
Others Ingo Hoffman Tom Wangler Ingo Hoffman Tom Wangler
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Outline

1. The University of Maryland Electron Ring
2. Source Physics
3. Transverse Physics
4. Longitudinal Physics
5. Future Directions

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HIF with electrons? Scaling Laws
1 keV 1 MeV 1 GeV 1 TeV
UMER
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Beam Dynamics Challenges for HIF

• Transverse
• Halo Formation
• Emittance Growth
• Instabilities
• Longitudinal
• Energy Spread
• Transverse-Longitudinal Coupling
• Compression
• Instabilities

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University of Maryland Electron Ring
UMER is designed to serve as a research platform
for intense beam physics

• Variable-Parameter over a wide range
• Long Path
• Well-Diagnosed
• Low-Cost!

The most intense beam in a strong focusing
lattice
A Tabletop Accelerator Experiment
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Dimensionless Space Charge Intensity
Matched Beam envelope equation (force balance)
0 ? c ? 1
In UMER, force from space charge can be as much
as 55 times the force from thermal pressure
(emittance)!
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Scalings with Space Charge Intensity
UMER Range
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UMER Schematic
10 kV Gun
Extraction/ diagnostic section
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UMER lattice
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Diagnostics Available

• Fast Current Monitors (2)
• Beam Position Monitors (17 BPMs)
• Phosphor Screens (18 P-Screens)
• End Diagnostic Chamber
• Energy Analyzer
• Pepper-pot Emittance (Phase Space) Monitor
• Slit-Wire Emittance (Phase Space) Monitor
• Faraday Cup

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UMER is a Complex Machine
Injection Line
Electron Gun
Ring Chambers
Diagnostic Chamber
gt 150 Magnets
Assembly, Alignment
Power Supplies, Wiring
Diagnostics
Beam Control
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UMER Photos (2002)
July 20022 Sections
Sep. 20024 Sections
Dec. 20029 Sections
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UMER Photos (2003)
July 200312 Sections
Sep. 200313 Sections Y
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New Injection Y-Design
Injector
IQF
RQ1
Ring
Mark Walter poster, Today (W)
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Source Physics
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Simulation with WARP PIC-code
WARP combines features of a plasma simulation
and an accelerator code

Courtesy of Alex Friedman

The Heavy Ion Fusion Virtual National Laboratory
D. P. Grote, et. al., Fus. Eng. Des. 32-33,
193-200
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Intense Beams Can Carry Waves
Experiment (100 mA) (top)
Beam patterns sensitive to initial velocity
distribution!
WARP Simulation (below)
S. Bernal, et al., NIM A 519, 380-387 (2004)
R.A. Kishek, et al., Phys Plasmas 10 (5), 2016
(2003).
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UMER Electron Gun
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Hollow Velocity Distribution
Construct New Distribution Uniform in
Space Velocity is a Gaussian with non-zero mean,
rotated about z axis, i.e. hollow in center.
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Hollow Velocity better fits experiment
Simulated Pepper-Pot
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Phase Space at Source Exit
Irv Haber poster, Tomorrow (Th)
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Transverse Physics
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First Experiments (during construction)
Rotated Beam
24 mA, 10 keV
1.0 m
RMS Mismatched
1.0 cm
S. Bernal (PAC 03)
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Skew Quadrupole (Rotational) Errors
Kishek, Barnard, and Grote, PAC 1999
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Injecting Rotated Beams ? Halo
Simulations R. Kishek Proc Halo 03
Experiment (Bernal, Li)shows similar features
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Quadrupoles with Electronically Adjustable
Skewness
H. Li (PAC 01)
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Beam Rotation Correction

• 24mA Beams (RC1-12)

Hui Li ( S. Bernal) poster, Today (W)
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Computer Control Tomography
700 mA pinhole beam
Note striations in beam and phase space ? due
to cathode grid
Hui Li ( S. Bernal) poster, Today (W)
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New 5-Beamlet Experiment
Bernal Haber Kishek
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Particle Trajectories x-x Phase Space
Isotropic
Anisotropic
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Longitudinal Physics
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Long Solenoid Experiment (LSE)
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Experimental Study of BeamEnergy Spread Energy
Analyzer Design

• High resolution
• (lt 1 eV for 10 keV beam)
• ns temporal resolution

Yupeng Cui poster, Tomorrow (Th)
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Energy Spread Measurement Results
Yun Zou poster, Tomorrow (Th)
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Laser-Generation of Perturbations
Courtesy Yijie Huo
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Photo Thermal Emission Beam
Thermionic only, 100ns pulse
Photoemission Thermionic 5ns pulse
Photoemission only (Cool cathode)
Current measurement with a fast (ltns) Bergoz
current monitor
Courtesy Yijie Huo
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Propagation of Longitudinal Perturbation
20mA Thermal-Emission Current 20mA Photo-Emission
Current
Beginning
End
Courtesy Yijie Huo
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Longitudinal Capture

• Beam End Evolution
• Focusing with Induction Gaps
• Multiple Pulses on beam

John Harris poster, Today (W)
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Spiral Generator for Gap Pulsers
Diode Ringing Suppression
Output Transformer
MOSFET Switching
Delay Line
Inversion of One Channel
Patents Pending
John Harris poster, Today (W)
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UMER Research Program

• Transverse
• Quadrupole Rotations
• Halos
• 5-Beamlets
• Anisotropic Beams
• Chaotic Mixing
• Longitudinal
• Electron Gun
• Beam Ends
• Perturbations Waves
• Energy Spread

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Conclusions

• Scaled experiments are an efficient way to learn
  about long-path beam dynamics issues
• Many new results during construction
• Closure of the ring promises exciting results
• See our Posters (3 Wed / 3 Thu)

Website http//www.ireap.umd.edu/umer Publication
s http//www.umer.umd.edu/