Post on 08-Apr-2022
transcript
WG5 Summary
Philippe Piot (NIU)John Lewellen (Argonne)
First things first
• Thanks to all of our participants– Interesting talks on a wide range of ideas– Good questions!
• Thanks to our colleagues in other groups, in particular:– Computation– EM Structures
What we talked about• Beam Sources
– Some quite unusual– Some used for “non-typical” purposes
• Beam Monitoring– Evolving field– Tomography (trans. & long.) becoming more common– Improvements in non-intercepting techniques
• Beam Control & Manipulation– Advanced techniques that need to be tested– Advanced techniques that already are interesting– Starting to use improved beam monitoring techniques
Beam Sources• “Directed” sources
– Time-synchronized pulse radiolysis (U. Tokyo)– Compton backscatter (U. Tokyo)
• “Beam Phyiscs” sources– A0 photoinjector (Fermilab)– SPARC photoinjector (Frascati) (incl. ellipsoidal blowout)– TW/SW photoinjector (UCLA)
• “Enabling” sources– Tevatron e- lenses– Polarized e+ source– Diamond amplifier photocathode
Three current profiles from TEL-1 e-guns
E-beam is strongly magnetzed in 2-40 kGmagnetic field Profile in theinteraction region isthe same (justscaled) as on cathode
Shiltsev
7/06 AAC 06
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Ep=4 keV, Ip=3uA, 81K
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Smedley
Beam Diagnostics• Longitudinal measurements are maturing
– CTR is almost “routine” for bunch length– Advanced methods for profile reconstruction with
CTR, phase-space projection with deflector cavities + dipoles
– Working towards “single-shot” CTR-based meas.
• Transverse measurements– Tomographic reconstruction is now widely used– New BPM designs for position and moment extraction– Ideas for full phase-space projections to a screen
Some Upcoming Non-Intercepting Techniques
• Quad cavity BPMs to extract beam moments, measure rms emittance
• Optical diffraction radiation to monitor high-energy beam size
• Metallic post BPMs• Photonic bandgap structures• Coherent edge radiation
• Questions: wakefields, beam-to-structure clearance
• (Not discussed in our WG: laser wire, EO techniques)
Technion - Israel Institute of Technology
Department of Electrical Engineering
Metallic Post BPM
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Investigations of Optical Diffraction Radiation on 7-GeV Beams at APS are Relevant to ILC Beams
ODR offers the potential for nonintercepting, relative beam-size monitoring with near-field imaging. This is an alternate paradigm to far-field work at KEK.
Submitted to Phys. Rev.
Edge Radiation Frequency SpectrumEdge Radiation Frequency Spectrum• Edge radiation is a variant synchrotron radiation while the beam crosses the boundary of a magnet.• Intensity is much higher than SR for wavelengths λ>>λc
• Spectral resolution will give most information (boost to long wavelength components)• Flat ER spectrum good for faithful response
• Radial polarization allows contrast with SR
E0 ω( ) ~ ω 21 3 cR
<< ω << ωc
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⎞ ⎠ ⎟ Synchrotron radiationSynchrotron radiation
Edge radiationEdge radiation
O.V. Chubar, N.V. Smolyakov, J.Optics, 24(3), 117 (1993) E ω( )~ ˜ I ω( )2
CER
λc ~ 50 nm
Ec ω( ) ~ Ib ω( )2
Rosenzweig
Intercepting Techniques
• OTR screen – commissioning at Fermilabfor p & p-bar imaging @ 150 GeV– Formation length effects observed?
• Movable emittance meter at SPARC probes phase-space evolution
• Transverse deflectors for long. profile measurements
• Phase-space reconstruction of “extreme beams” in UMER
f Preliminary Tevatron Uncoalesced Proton Beam Measurements
(a) Single-turn OTR image of 3e11 uncoalesced protons. (b) and (c) are X and Y beam profile data with fits, respectively.
(a) Two-turn OTR image of 3e11 uncoalesced protons with double Gaussian fit of vertical profile. (b) and (c) Same as (a) but with increased vertical injection mismatch from the Main Injector into the Tevatron.
Scarpine
Phase Space Tomography - Different Distributions
• χ=0.72 , I=7mA (space charge)• Initial Distribution: Five Beamlet• Highly non-uniform distribution
WARP Tomography
Tomography can be used to map the phase space of complex multi-beamlet distributions
Stratakis – U. Md.
Possibilities...
• Combine:– Transverse deflector– Quad cavity BPMs
• Extract– RMS profile information w/o blocking beam
Beam Control• “Beam Taffy” - Manipulate all dimensions of phase space
– Emittance exchange: transverse/longitudinal– Flat-beam: Transverse aspect ratio– Velocity bunch compression
• Beam formation– Elliptical pulse generation– Photocathode drive laser pulse shaping
• Machine control– Response matrix formulation for steering & matching– Migrate SR techniques to ERLs and single-pass linacs
KJK, AAC, July 10-14, 2006, PhaseSpace
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Generating a Flat Beam with Angular Mom. Dominated Beam(D. Edwards, …), (Y.-e Sun)
experiment simulation
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Maximum likelihood: Fermi-Dirac distribution!
Maximum likelihood: Fermi-Dirac distribution!
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Simulation & Modeling
• Advanced codes are being applied to high-brightness sources– Analytic approaches (Green’s function solver)– wavelet-based space charge solvers– “binned” Poisson solvers for energy spreads– full-on 3D PIC codes with improved geometric
modeling
• Realistic cathode modeling
Numerical Solution of Er (C. S. Park)
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Hess
Wanted!• Realistic cathode data to go with the realistic
cathode models– measurements of electron spectra from the cathode is
needed for:• band structure• thermal emittance
– quantum efficiency at multiple wavelengths– surface characterization for various prep. techniques
(metal)– depth profile for material composition (semiconductor)
• See John Smedley (BNL) for details