Particle Accelerators and their Applications

Transcription

1 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 Research sponsored by US DOE & DOD ONR 1

2 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: Chaos and Nonlinear Dynamics Space & Fusion Plasmas Beam Physics Microwaves and Electronics Nanoscience and Engineering Materials Processing (using microwaves, plasmas, ion beams) 2

3 Outline 1. What are Particle Accelerators? 2. Common Accelerator Applications 3. Research at Maryland 4. Opportunities for Students 3

4 Do you know how your TV Works? Anode (A) Heat Cathode (K) High Voltage Phosphor Screen 4

5 Accelerator Schematic (many km) Source Transport Target Accelerate 5

6 CERN, LHC The Largest Accelerator Large Hadron Collider (LHC), CERN, Geneva 6

7 Accelerator Applications Science Research Particle Physics Nuclear Physics Astrophysics Probing material structure Biosciences Microscopy Artifact dating Light sources (includes X-ray) Neutron sources Lasers Industry Ion implantation Food Sterilization Lithography Nanotechnology Accelerators Medicine Imaging Isotope production Cancer Radiotherapy Environment Radioactive waste treatment Energy Production Controlled nuclear fusion 7

8 Accelerator-Driven Neutron Sources Spallation Neutron Source, Oak Ridge, TN Transportation Electronics Manufacturing Environment Medicine Engineering Plastics 8

9 Energy: Controlled Fusion w/ Heavy Ion Beams 9

10 Light Sources Bend magnet radiation Undulator radiation Technology Spectrum 10

11 One Solution: Free Electron Lasers (FELs) amplified radiation electron beam bunched electron beam input radiation Radiated wavelength: λ λr + 2γ w (1 K 2 ) 2 w Normalized vector potential of undulator K w = 0.93 B rms (Tesla) λ w (cm) order unity 11

12 Free Electron Lasers illuminate the Nanoworld LCLS, X-ray FEL, Stanford, CA 1.5 Å, femtosec 10-2 m 10-3 m 1 cm 10 mm 10 6 nanometers = Gordon Moore The First Computer DNA, Proteins ~ 2.5 nm Nanoworld Microworld 10-4 m 10-5 m 10-6 m 10-7 m 10-8 m Ultraviolet Visible Infrared Microwave 0.1 mm 100 μm 0.01 mm 10 μm 1,000 nanometers = 1 micrometer (μm) 0.1 μm 100 nm 0.01 μm 10 nm 10-9 m 1 nanometer (nm) m Soft x-ray nm

13 Medical Diagnosis and Treatment Tomography Treatment of Cancer with Protons or Heavy Ions 13

14 Accelerators are complex machines 14

15 Beam Dynamics x y z e Paraxial assumption v x, v y << v z 1. Randomness 2. Mutual Repulsion Space Charge Need to apply focusing Magnets 15

16 Space Charge Adds Complication Beam distribution changes Exotic Phenomena Waves and Fluctuations Halos Instabilities Quality degradation 16

17 Requires Extensive Modeling & Simulation Problem: Space charge force depends on beam distribution, which constantly evolves in response to the forces Typical beam may contain particles Typical accelerator measured in km, while focusing magnets vary on a scale of cm. 17

18 Understanding Requires Detailed Knowledge Beam patterns sensitive to initial velocity distribution! Experiment (100 ma) (top) [Bernal] 1.0 cm Q1 Q2 Q3 Q4 WARP Simulation (below) [Kishek] K-V Distribution 1.0 cm Semi-Gaussian Distribution Hollow-Velocity Distribution 18

19 The University of Maryland Electron Ring Use 10 kev electrons to inexpensively model space charge effects in other accelerators 3.7 m Energy 10 kev Circulation time 200 ns Energy Spread 20 ev Pulse length ns Current Range rms Emittance ma μm Zero-Current Tune Depressed Tune

20 UMER Magnets & Lattice 72 Quads (~ 7.8 G/cm) 32 cm 36 Dipoles (~ 15 G) 20

21 UMER Multi-Turn: Low-Current Results (Work in Progress) test2 : Beam Current Per Turn from BPM Typical BPM signals for low current 1 mv/div up to 125 turns 500 ns/div time along pulse [ns] Zero-current Tune=7.3 Beam Current Estimated Emittance* Tune Depression Tune Shift Injected 690 μa 5.6 μm After 25 turns 300 μa 4.6 μm *4rms, unnormalized S. Bernal, Proc. Advanced Accelerators Concepts Wkshp

22 Multi-Turn: More Intense Space Charge p Beam Current (ma) (Work in Progress) up to 60 turns Time [ns] Zero-current Tune=7.3 Injected Beam Current 18.6 ma Estimated Emittance * 24 μm Tune Depression 0.55 Tune Shift 3.3 After 9 turns 3.6 ma μm *4rms, unnormalized M. Walter, Proc. Advanced Accelerators Concepts Wkshp

23 Opportunities for Graduate Students Research Assistantships available Need strong academic record Good background in Electromagnetism Experiments Diagnostics Electronics Controls Mechanical Skills Theory and Simulation 23

24 Tomography: Characterization of Beams Additional projections at different angles add information to our image of the phase space Different Distribution X X WARP X X Tomography X 1 mrad 1 cm X 1 mrad 1 cm D. Stratakis, PRSTAB, to appear (2006). X WARP simulation hollow-velocity X Reconstructed by tomography on simulation results 25

25 Propagation of Density Perturbation on Beam 20 ma thermal-emission beam current 20 ma photo-emission beam current WARP simulation Beginning Current (A) End Z (m) Y. Huo, to be published 26

26 Space charge converts density perturbation to an energy perturbation 0 Group 1 - initial beam current 10 Group 2 - initial beam current Current/A current/ma current/ma time/ns time/ns Initial Current vs. Time Group 3 - initial beam current Group 4 - initial beam current current/ma current/ma time/ns time/ns time/ns K. Tian, et al., PRSTAB 9, (2006). 27

27 ENEE 686 Spring 2007 Charged Particle Dynamics 3 Credits! Register Now! MW 12:30 1:45 PM Prof. Rami A. Kishek 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: Particle accelerator systems Phase space concepts Focusing and transport optics Acceleration Techniques Collective phenomena Self-consistent theory of beams Emittance growth and control Radiation Applications of Accelerators 28

28 Visit Our Website for More Information 29

29 I like to thank my colleagues University of Maryland Electron Ring (UMER) Team: Patrick O Shea Martin Reiser Rami Kishek Irving Haber Brian Beaudoin Renee Feldman Don Feldman Ralph Fiorito Henry Freund Terry F. Godlove Kevin Jensen Gang Bai Mark Walter Junior Scientists: Santiago Bernal Mark Walter Bryan Quinn Quinn Brian Beaudoin Irving Haber Charles Tobin A. Shkvarunets Christos Papadopoulos Patrick O Shea Graduate: Gang Bai Kai Tian C Papadopoulos Donald Dave Feldman Sutter Diktys Stratakis Charles Tobin Kai Tian Santiago Bernal Mike Holloway Dave Gillingham David Rami Demske Kishek Nathan Moody Renee Feldman Former: Yun Zou Jonathan Diktys Neumann Stratakis Yupeng Cui Hui Li Yijie Huo John Martin Harris Reiser Ralph Fiorito Terry Godlove Webmaster 30