j.s. wurtele- x-ray free electron lasers

Download J.S. Wurtele- X-Ray Free Electron Lasers

Post on 15-Oct-2014

25 views

Category:

Documents

6 download

Embed Size (px)

TRANSCRIPT

X-Ray Free Electron LasersJ.S. WurteleUCB and LBNLS N S N

e

N S N S

P

Davidson Symposium Light PPPL June 12, 2007

w

X-Ray FELs

Two Livingston PlotsParticle accelerators Light Sources

Panofsky

EU FEL

Evolution of synchrotron radiation sourcesX-Ray FELsGoals: High average flux High peak power Temporal coherence Spatial coherence Attosecond pulses Synchronization Flexibility Implications (current technology): Large machines, GeV Energies Critical Physics Optical manipulation of phase space High brightness beam generation and preservation Wiggler technology

X-ray sources expand

JAPAN [SPRING 8]EU XFEL [DESY]

LCLS [SLAC] FEL

Current Energy Repetition rate Peak X-Ray Power

~3.5kA ~13.6GeV ~120Hz

~8GW

Vision for a future LBNL light source

FEL array at the Bevatron site

ALS

Injector

Linac in tunnel

Vision for a future light source facility at LBNLA HIGH REP-RATE, SEEDED, VUV SOFT X-RAY FEL ARRAY Array of configurable FELs Independent control of wavelength, pulse duration, polarization Configured with an optical manipulation technique; seeded, attosecond, ESASE Beam distribution and individual beamline tuning ~2 GeV CW superconducting linac

Beam manipulation and conditioning

Low-emittance, high rep-rate electron gun

Laser systems, timing & synchronization

FEL BASICSS N S N

e

Light

N S N S

P w

Limits

Spread in this term is harmful!

What drives X-ray FELs towards large energy electron beams?

1. Coherent emission--bunching at X-ray wavelengths

2. Limits on our ability to create and propagate high brightness electron beams

3. Limits on our ability to build short wavelength wigglers

Dephasing from transverse motion

JBz

JBundulator

d] K Kr ! 2k w dz Krz

OJ B

JBE/E

our inability to We are limited bymake high quality beams

with conditioning

allows relaxed emittance requirement in FEL-but we do not know how to produce required conditioning in a practical system (yet)

SASE FEL: amplification of fluctuations

Single pass synchrotron radiation spectrum (Catravas, et al, @BNL/ATF,)

SASE spectrum and temporal shape has spikes-poor longitudinal coherence

Seeded FELENHANCED CAPABILITIES FOR CONTROL OF X-RAY PULSE

Pulse profile0.35 0.30 0.3 0.25 Power (GW) 0.20 0.15 0.10 0.05 0.00 -700 0.0 12389

Spectrum0.4 Photons/meV (X10 )

SASE

0.2

0.1

-600

-500

-400 Time (fs)

-300

-200

-100

1239

1240 Photon Energy (eV)

1241

1242

0.6

0.14 0.12

0.5 ) Photons/meV (X10 0.4 Power (GW)9

0.10 0.08 0.06 0.04 0.02 0.00 1238

0.3

25 fs seedSeeded FEL close to-600 -500 -400 Time (fs) -300 -200 -100

0.2

0.1

0.0 -700

1239

1240 Photon Energy (eV)

1241

1242

0.6

transform limit9

30 25 ) 20 15 10 5 0 1238

No monochromator

0.5

0.3

500 fs seed

0.2

0.1 0.0 -700

-600

-500

-400 Time (fs)

-300

-200

-100

Photons/meV (X10

0.4 Power (GW)

1239

1240 Photon Energy (eV)

1241

1242

Electron beam is 1.5 GeV, energy spread 100 keV, 250 A current, 0.25 micron emittance; laser seed is 100 kW at 32 nm; undulator period 1 cm

Phase space manipulationManipulate beam phase space can have many advantages:Enhanced gain Seeding radiation pulse for harmonic cascades Attosecond pulses Synchronization Relax beam quality constraints (conditioning) Lower energy for given wavelength

Many of these ideas are realized by laser interactions with the electron beam prior to the radiation generation. Some examples

Lasers manipulate longitudinal phase space during interaction in wigglerE( t )slice ~ 1 fs

Laser pulse ~ 5 fs 100 fs e-beam ~

Harmonic cascade seedThis cartoon is realized by manipulation of beam phase space with short pulse lasers. The idea is to condition and select specific slices of electrons to radiate differently (in direction, frequency, intensity, etc.). For synchrotron sources this has already been accomplished: Zholents & Zoloterev(1996); Schoenlein, et al, 2000; Khan, Part. Acc. Conf. 2005. For FEL see Zholents et al (20032007)

High Gain Harmonic Generation (HGHG) seed with a laser pulse and radiate at a harmonic

Extends energy reach, lower powere- bunch laser pulse

P

0

P0 nRadiator Longer wiggler

Modulator Short wigglerOutput

e- beam phase space:

dispersive chicane

Input Energy

T

phase

T

nT

nT

Laser modulates e-beam energy

Bunched beam radiates strongly at harmonic in a downstream undulator Dispersive section introduces bunching

L.-H. Yu et al, Science 289 932-934 (2000) L.-H. Yu et al, Phys. Rev. Let. Vol 91, No. 7, (2003)

Cascaded harmonic generation schemeseed laser pulsemodulator radiator

disrupted regionmodulator radiator

tail

head Unperturbed electrons WE ~ WE (0)

Low I electron pulse

Delay bunch in micro-orbit-bump (~50 Qm)

Seed laser pulse Tbunch >> TMO PMO >> Pshot

FEL modulator LW < LSAT Strong bunching

3rd - 5th harmonic radiator

3 - 5th harmonic FEL modulator / low gain amplifier LW < LSAT

3rd - 5th harmonic radiator

HHG laser seed--an alternative to harmonic cascadesExample with seed at 30 nm, radiating in the water window First stage amplifies low-power seed with optical klystron More initial bunching than could be practically achieved with a single modulator Output at 3.8 nm (8th harmonic)100 kW P=30 nm

Modulator30 nm, L=1.8 m

Modulator30 nm, L=1.8 m

Radiator3.8 nm, L=12 m

1 GeV beam 500 A 1.2 micron emittance 75 keV energy spread

300 MW output at 3.8 nm (8th harmonic) from a 25 fs FWHM seed

Courtesy H. Kapteyn

Or, X-ray laser seed

Gullans et al. (2007)

Gun

Beam manipulation linac

FELs

FEL performance is governed by beam brightness: Brightness = # electrons/6D-phase space volume This number will NOT get larger---determined by gun physics and can grow through various instabilities

RCD circa 89

Gullans et al, 2007

Plasma-based Electron Linac~ ( ~ ! [ d Klystr on M icrow ave ( P ow er Sou r ceConventional Linac

W ave-gu id e stru ctu re

E

Ez : 10 - 200 MV/ m Lint : km 's

W = e Ez LintElectron beam surfing on plasma electric field Laser driven plasma based linacEz : 1 0 - 1 0 0 GV / m L int : laser dif fr act ion lengt h

laser pulse 40 0 10 20 30 50 60 (B. Shadwick, UC C B/ BP)

19

Performance comparisonPARAMETER SPACE COMPLEMENTS OTHER FACILITIES10 10 Average Brightness [Ph/(s 0.1% BW mm mrad )]2 26Seeded FEL, 750 fs (1.2 keV)

25European XFEL (12 keV)

10 10 10 10 10 10 10 10 10 10 10

24 23 22 21BESSY FEL (1 keV)

2

Seeded FEL, 50 fs (1.2 keV)

Cornell ERL (6 keV) LCLS (8 keV) FLASH (200 eV)

20 19 18 17 16 15 14Seeded FEL, 100 as (1.2 keV)

3rd Generation Storage Rings

2nd Generation Storage Rings

10

-5

10

-4

10

-3

10

-2

10

-1

10

0

10

1

10

2

10

3

X-Ray Pulse Duration [ps]

Many people within LBNL contribute to new light source

Walter Barry Dan Bates Ken Baptiste Ali Belkacem John Byrd Chris Celata Chris Coleman-Smith John Corlett Stefano DeSantis Larry Doolittle Roger Falcone Bill Fawley Graham Fleming Miguel Furman Tom Gallant Mike Greaves Steve Gourlay Michael Gullens Gang Huang Zahid Hussein

Preston Jordan Jerry Kekos Janos Kirz Jim Krupnick Slawomir Kwiatkowski Steve Leone Derun Li Steve Lidia Steve Marks Bill McCurdy Pat Oddone Howard Padmore Emanuele Pedersoli Gregg Penn Dave Plate Ilya Pogorelov Ji Qiang Alex Ratti Ina Reichel David Robin

Kem Robinson Glenna Rogers Rob Ryne Fernando Sannibale Bob Schoenlein Andy Sessler Kiran Sonnad John Staples Christoph Steier Jean-Luc Vay Marco Venturini Will Waldron Weishi Wan Russell Wells Russell Wilcox Jonathan Wurtele Sasha Zholents Mike Zisman Max Zolotorev

Extras

Potential for attosecond x-ray production

800 nm

spectral broadening and pulse compression e-beam

e-beam harmonic-cascade FEL

one period wiggler tuned time delay for FEL interaction at chicane 800 nm

2 nm light from FEL

2 nm modulator

chicane-buncher

1 nm coherent radiation

dump end station

1 nm radiator end station

Zholentz and Fawley PRL 2004

X-rays from plasma sources

Already demonstratedbeams make x-rays More elaborate ideas based on ion channels [Whittum; E157SLAC]The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Rousse et al, PRL 04

Many groups worldwide are working on this Plasma yield naturally short pulses, but hard to reach FEL intensities with spontaneous emission [N vs N^2]

The Advanced Photoinjector Experiment rate RF photocathode gun High repetitionCathode Mounted on Coaxial Center

Recommended

View more >