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!