Highlights of the 47th ICFA Workshop on the Physics and
Applications of High Brightness Electron Beams
J.B. Rosenzweig
UCLA Dept. of Physics and Astronomy
Future Light Sources 2010
SLAC March 3, 2010
Physics and Applications of High Brightness Electron BeamsMaui, November 16-19, 2009
Latest in series resulting from joining “High Brightness” and “Arcidosso” workshops
Endorsed by ICFA subpanels on Beam Dynamics and Advanced and Novel Accelerators
Mid-Pacific setting to encourage
Asian participation
Committees
Organizing committee
Co-chairs J. Rosenzweig (UCLA) L. Palumbo (Univ. Roma “La
Sapienza”) M. Uesaka (U. Tokyo)
L. Serafini (INFN-Milano) C. Brau (Univ. Vanderbilt) H. Braun (PSI) K-J. Kim (UC/ANL) G. Dattoli (ENEA) S. Milton (Sinc. Trieste/ANL) S. Chattopadhay (Cockroft Inst.) P. Emma (SLAC) J. Rossbach (DESY) W. Leemans (LBNL) V. Yakimenko (BNL)
Program committee M. Ferrario (INFN-LNF), Chair
C. Pellegrini (UCLA) W. Barletta (MIT) Z. Huang (SLAC) G. Krafft (JLAB) M. Poole (Daresbury) L. Giannessi (ENEA) X. Wang (BNL) R. Kishek (Univ. Maryland) M. Eriksson (MAXLAB) F. Gruner (LMU/MPQ) T. Kamps (BESSY) D. Giulietti (Univ. Pisa) G. Hoffstaetter (Cornell) F. Stephan (DESY) T. Shintake (SPring-8)
History
1999-Los Angeles: The Physics of High Brightness Beams - merging of ion/electron communities
2002-Chia Laguna: The Physics of and Applications High Brightness Beams – joining of Arcidosso series, light source applicaitons
2005-Erice: The Physics of and Applications High Brightness Beams. Theme: birth of the SASE FEL
2009-Maui: The Physics of and Applications High Brightness Beams. Theme: New directions, plasma sources, etc.
Statistics
The workshop had 105 registered attendees from across the beam physics community, among them 10 students with partial support from the workshop.
The workshop received financial contributions from ANL, LBNL Sincrotrone Trieste, SLAC, UCLA, and the Univ. of Tokyo.
Conference secretariat headed by Carly Nguyen of UCLA, and included Francesa Casarin and Daniela Ferrucci of INFNLNF.
Further information on the workshop is available at:
http://pbpl.physics.ucla.edu/HBEB/index.html
MissionHigh brightness electron beams are playing an increasingly critical role in two frontier fields that are now yielding results that provoke considerable excitement and activity across the scientific community: radiation generation methods and advanced acceleration schemes. Such cutting edge radiation production methods include variations on the revolutionary 4th generation device, the free-electron laser, as well as inverse Compton scattering of intense lasers. These diverse approaches are thus able to create high peak and high average power light sources, with applications in ultrafast sciences and the Å level, as well as in nuclear and high-energy physics. Likewise, high brightness beams are at the center of many future accelerator schemes, e.g. based on high gradient electron and laser wakefields. Indeed, laser wakefield accelerators are now entering the proof-of-application phase, where unique light sources based on advanced acceleration schemes are enabled. The goal of this workshop is to provide a comparative study of the generation, manipulating, modeling and measuring of high brightness electron beams, and the multitude of underlying, interdisciplinary methods linking the physics of these beam systems to the physics of advanced applications.
Plenary talks and working groups
1. Sources, including photoinjectors and plasma-based sources2. Manipulation and diagnosis of high brightness beams 3. Theory and modeling, simulation challenges4. Applications of high brightness beams in advanced accelerators and light sources.
* November 16 LCLS Injector Performance and Impact on Lasing - D. Dowell High Brightness Beam Measurements at PITZ - F. Stephan Superconducting RF Photoinjector Development - T. Kamps Intense Space Charge Effects of Relevance to FEL Injectors - R. Kishek On the Control of e-Beam Parameter with Laser Plasma Accelerators - V. Malka Overview of Advanced Cathodes for HBB - L. Cultrera Novel high brightness beyond photocathodes - C. Brau * November 17 Advanced Laser Pulse Shaping - H. Tomizawa Photoinjector Blow Out Regime Experiments at UCLA - P. Musumeci Velocity Bunching at SPARC - D. Filippetto Generation of Train of Short Electron Pulses for Wakefield Expts. - P. Muggli Beam Diagnosis at the Fs frontier - H. Loos Tomographic Phase-Space Mapping of High-Brightness Beams - D. Stratakis X-ray FEL Oscillator: Promises and Challenges - K-J. Kim
* November 18 Emittance Compensation Theory & Experimental Results - C. Wang Thermal Beam Equilibria in Periodic Focusing Fields - C. Chen Physics of a 10 GeV laser-plasma accelerator - E. Esarey Brightness Characterization of Electro Beams from Plasma Injectors - A. Rossi Echo harmonic-techniques for Introducing NM Beam Structures - D. Xiang Overview of LWFA Experiments - W. Leemans High Average Power, High Brightness Electron Beam Sources - F. Sannibale
* November 19 Overview of Thomson/Compton Sources - R. Kuroda Plasma and Dielectric Wakefield Acceleration Experiments at SLAC - M. Hogan Sub-fs Electron Pulses for FEL and PWFA applications - J. Rosenzweig Soft X-ray Undulator Radiation from Laser Accelerated Electrons - M. Fuchs Prospects for a Table Top FEL - C. Schroeder Laser-structure accelerators - B. Cowan The Coolest Beam in the World - J. Luiten
Lets proceed from the cathode forward….
Overview of photocathodes- L. Cultrera (INFN-KNF)
Fundamental tension between QE and thermal emittance…
Mitigated by using semi-conductor cathodes… but these are slower
Coatings on metal photocathodes: improving lifetime
Wide band-gap thin film coatings give interesting results Example: CsBr, transmissive
at 257 nm
MgF coatings improve Schottky by field inside coating
Emission in the visible: Yttrium
Photoemission at 400 nm
Lifetime issues in SPARC studies
Superconducting guns: Pb cathodes
Lead is excellent candidate cathode for SC guns
Usual tradeoff between QE and thermal emittance
J. Smedley, T. Rao and J Sekutowicz, Phys. Rev. ST Accel. Beams, 11, 13502 (2008)
Semiconductor photocathodes
High QE through electron-phonon scattering (slow)
Coatings improve lifetime here too
Polarization with strained GaAs
Frontier: diamond amplifier cathode
Gain over 200; beams emitted
Life after photocathodes-C. Brau (Vanderbilt)
Field emission approaches quantum brightness limit
Dedicated study of diamond tips…
6 nm tip radius
Improvements through gated array
Diamond FEA already FEL quality (high average power oscillator)
Diamond FEAs to be installed in SC guns
Carbon nanotubes approach quantum emission limit
Central role of adsorbate atoms in mediating emission
The coolest beams in the world
-O.J. Luiten (Eindhoven)
Standard photocathodes at othe 0.1-1 eV temperature
Rydberg atom gas in laser trap gives orders of magnitude improvement possibility
Ultra-cold beam experimentsFirst tests give three orders of magnitude
temperature improvement
Immediate applications
Ultra cold ion beams
Ultra-fast electron diffraction
Ultrashort laser pulses on the cathode: blow-out regime and multiphoton photoemission – P. Musumeci (UCLA)Blowout regime dynamically produces high quality
electron bunch – ellipsoidal shape
Very high 6D brightness with low Q
Deflector enabled observations
Application: ultra-relativistic electron diffraction
Multiphoton photoemissionPhotoemission observed in IR!
Lower efficiency compensated by regaining uv conversion losses
Superconducting RF Photoinjector Development -- T. Kamps (HZB)Obvious approach to high average current
photoinjectors for FEL BNL, Berlin, Dresden…
Challenges: cathode, beam focusing
High Average Power, High Brightness Electron Beam Sources - F. Sannibale (LBNL)
Normal conducting option presented
Cooling gives strong field limitations
LCLS Injector Performance and Impact on Lasing- D. Dowell (SLAC)
Remains the gold standard
Many problems in high field photoinjectors mitigated
Very low charge mode at LCLSHigher brightness, ultra-short pulse for advanced
FEL
Velocity bunching at SPARC –D. Fillipetto (INFN-LNF)Advanced compression technique, avoids “the
bends”
Compression x3 with little emittance growth
Longitudinal phase space schematic for velocity bunching
An X-Ray FEL Oscillator: Promises and Challenges -- Kwang-Je Kim (Chicago/ANL)
An X-ray pulse is stored in a diamond cavity
multi-pass gain & spectral cleaning
Provide transform limited BW
Zig-zag path cavity for wavelength tuning
Compelling brightness argument
Low charge, high brightness beams… again
Plasma and Dielectric WakefieldAcceleration Experiments at -- M. Hogan
Enormous accomplishments at FFTB, looking towards FACET
A Light Source Scenario using Dielectric Wakes
Pulse train may not be needed or desirable…
Instead, look for enhanced transformer ratio with ramped beam
Does this work with multi-mode DWA?
Scenario: 500-1000 MeV ramped driver; 5-10 GeV FEL injector in <10 m
Ramped beam R>>2
Symmetric beam R<2
Ramped beam R>>2
A FACET scenarioCharge: 3 nC
Ramp: L=2.5 mm
Energy: 500 MeV
Structure: a=100 mm, b=100 mm, e=3.8
Fundamental f=0.74 THz
Performance: >GV/m accel., R=24 (12 GeV possible)
Sag in wake due to multi-mode
TV/m plasma wakefield accelerator using low charge, ultra-short beam –-J. Rosenzweig, UCLA
Original proposal to scale beam charge to pC levelVelocity + chicane bunching preserves <3-6 E-8
emittance
Single spike FEL, sub-fs (few 100 attosecond) operation
€
B = 2 ×1017 A/m2
€
ΔωΔt = 1.67
Use Table-top XFEL undulator?LMU MPQ-centered collaboration (BESSY, LBNL, UCLA, etc.)
UCLA collaboration on advanced hybrid cryo-undulator (Pr-based, SmCo sheath, Fe pole), 9 mm period, >2 T
Need short lu high field undulator for X-rays @1 GeV – critical for traditional linac sources too…
With ultra-high brightness beam, one may have very compact, extended capability FELs
Simulated 9 mm cryounduator performance at 30K (Maxwell, Radia, Pandira)
Example: SPARX w/sub-fs pulseWavelength reduction (3 nm->6.5 Å)
Ultra-short saturation length (10 m)
LCLS photon reach at 2.1 GeV on 5th harmonic
Simulated performance on fundamentalMW peak power at 1.5 Å, 5th harmonic
Example: LCLS w/sub-fs pulseUse even shorter 0.25 pC beam, 150 as pulse
Single spike w/standard LCLS undulator
Obtain ultra-compact “LCLS” at 4.3 GeV
Extend energy reach to 83 keV (0.15Å)
Gain evolution for 1.5 Å 4.3 GeV (0.25 pC)Gain evolution at
13.6 GeV, 0.15 Å
Ultra-short, high brightness beam:IR wavelength PWFA
Ultra-high brightness, fs beams impact HEP strongly…
Use 20 pC LCLS beam in high n plasma
In “blowout” regime: total rarefaction of plasma e-sBeam denser than plasmaVery nonlinear plasma dynamicsPure ion column focusing for e-sLinac-style EM acceleration General measure of nonlinearity:
€
˜ Q ≡Nbkp
3
n0
= 4πkpreNb
<<1, linear regime
>1, nonlinear "blowout"
⎧ ⎨ ⎩
MAGIC simulation of blowout PWFA case
-1.5
-1
-0.5
0
0.5
1
1.5
0 0.5 1 1.5 2 2.5
.
F/m
ec
ω
p
k
p
r
F
z
F
r
Wakes in blown out region
Optimized excitation at LCLSBeam must be short and narrow compared to plasma skin depth
In this case implies , blowout
With 2 fs LCLS beam we should choose
For 20 pC beam, we have
Linear “Cerenkov” scaling
1 TV/m fields (converted Er)
Collaboration initiated UCLA-SLAC-USC Basic science: coherent radiation, BSI ionization
€
nb >n0
€
σ r <kp−1
€
σz <kp−1
€
n0 = 7 ×1019 cm-3
€
˜ Q = 7
OOPIC simulation of LCLS case
€
eEz,dec≅4e2Nb
σ z2
Laser-driven undulator source -- M. Fuchs (MPQ)
Plasma acceleration gives 1st observed X-rays
W. Leemans discusses application further…
Aloha from MauiMahalo: thank to all for coming, and contributing at
such a high level
Look for updates on publications on website JACOW submission formalities, open soon
Particular emphasis on invited, summary talks (6 pages)
PRSTAB special option
To the farther future...
First suggestion (from D. Stratakis): Crete 2011We are open to all ideas that fit the theme!