Recent experiment results and progress of Tsinghua Thomson Scattering X-ray source

(TTX)

Ch.X. Tang (唐传祥)

*Tang.xuh@tsinghua.edu.cn

清华大学工程物理系

Department of Engineering Physics, Tsinghua University

@ Workshop on The Physics and Applications of High Brightness Electron BeamsMaui, Hawaii – November 16-19, 2009

Content• 1. Introduction to TTX Project• 2. Recent beam experiments • 3. Progress of TTX• 4. Summary

1 An Electron and Photon Multidisciplinary Research Lab. In Tsinghua University

1 Tsinghua Thomson Scattering X-ray Source - Phase I

Time Step rms−emittance vs Time or Zparameter_3_3.tbl 5−25−2008 3:20:02

Z(cm)

kE(MeV)

0

5

10

15

20

25

30

35

40

45

0 50 100 150 200 250 300 350 400 450

kE(M

eV)

Time Step rms−emittance vs Time or Zgood2.TBL 6−09−2008 22:12:24

Z(cm)mm−mrad

.05

.10

.15

.20

.25

.30

.35

10 20 30 40 50 60 70 80 90 100 110 120

Xrms

(mm)

Yrms(mm)

UV & TW Lasers

x-ray

TW fsLaser

UV Laser

Control Room

RF Power Source

Cooling Water

Layout of the TTX-I

1 TTX- Phase I

1 TTX-Simulated Parameters of Phase I

0.33%Energy spread

8.4X106(90deg)~5.5X107(180deg), Number of photons160(90deg)~1000(180deg) fsPulse duration24(90deg)~48(180deg) keVPhoton energy

x-ray pulse0.03 mm(x),0.025mm(y)Beam radius

0.7 nCCharge/microbunch1 psBunch duration45 MeVEnergy

Electron beam~0.031 mmFocal spot radius30 fsPulse duration500 mJPulse energy800 nmWavelength

Laser beam

1 TTX- Phase II Mini SR

Circumference ~12meterselectron : energy 50MeV, pulse length10ps, RMS energy spread 0.2%laser photon : wavelength 800nm and stored energy 1mJ.Frequency 25MHzX-ray Photons ~109s-1

Courtesy from Peicheng Yu, et al, Optics for the lattice of a compact storage ring forCompton X-ray source, Chinese Physics C (HEP & NP) Vol 32, 2008

1 TTX- Optics Parameters of the LESR

2 A Primary Experiment in THU

Macro-pulse of electron beam about 4μs

Pulse of Laser beam about 10ns

B W 电 子 束 激 光 束

瑞 利 长 度

Electron Bunches Laser Pulse

Rayleigh Length

CCD image of electron and laser beam at interaction point (up:electron, down:laser)

2 A Primary Experiment in THU

电子束能散测量

-5

0

5

10

15

20

25

14.5 15 15.5 16 16.5 17

E（Mev）

I(m

A) 0.85MeV(FWHM)

Energy Spread

2 A Primary Experiment in THU

1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.60.6

0.8

1

1.2

1.4

1.6

1.8

2

T (T/m)

Hor

izon

al b

eam

siz

e (m

m)

Experiment data Least squares fit

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.70.6

0.8

1

1.2

1.4

1.6

1.8

2x 10

−3

T (T/m)

Ver

tical

bea

m s

ize

(mm

)

X direction

εrms,x=15.1 π.mm.mrad

Y direction

εrms,y=12.7 π.mm.mradEmittance Measured by Quad.

Pulse Current 105mA

The scattering x-ray photon number simulation at the measured electron beam emittance

Parameters of Preliminary experimentSimulation of X-ray flux by Cain

2 A Primary Experiment in THU

Pulse Width： 5.8 ns Amplitude： 6.5 mV

Efficiency of the Detector：~5% Working Voltage： 1400 V

Amplified Factor： ～2X105 Photon Number per Pulse：～1.7X 104

2 A Primary Experiment in THU

190mm 175mm 175mm 316

180 23

0

ICT

771mm

891mm

1792mm

2395mm

Photocathode RF gun

Quadrupole

Diagnostic cavity

Compressor chamber & interaction chamber

MCP

Dipole CollimatorNormal incidence cavity for UV light

Off-axis parabolic mirror with hole

2 A Recent Thomson Scattering Experiment with Photocathode RF Gun

Thomson scattering X-ray source experiment

TW laser

Photocathode RF gunInteraction chamber

2 A Recent Thomson Scattering Experiment with Photocathode RF Gun

Scattering X-ray

Bremsstrahlung

Scattering X-ray+ Bremsstrahlung

2 Signals from MCP

Laser beamWavelength 800 nmPulse energy 120 mJPulse duration 60 fsFocal spot radius <50 μm

Electron beamEnergy 3 MeVBunch duration <3 psCharge/microbunch ～0.1 nCBeam radius 0.8 mm(x),0.4mm(y)

x-ray pulsePhoton energy 280eVPulse duration <3 psNumber of photons 7.3X103 / 6.4x103 (Measured)

2 A Recent Thomson Scattering Experiment with Photocathode RF Gun

Transverse Phase Space Measurement Based on Computerized Tomography

SART（simultaneous algebraic reconstruction technique ）

Bunch length measurement with coherent diffraction radiation

Emittance measurement by multi-slit

2 Beam Diagnostics: By Y.C. Du & D. Xiang

Bunch Length Measurement by RF Deflecting Cavity

2 Beam Diagnostics: By J.R. Shi

Subsystem installation completed

800nm, 3TW,30fs

266nm, 1mJ, 30fs

50MW,50Hz

4 TTX in Progress-Laser System: by LX Yan

Hor

izon

-CO

scill

ator

Evol

utio

n-30

20m

J@1k

Hz

Spec

traPh

ysic

s Pro

-350

-10

1.4J

,532

nm@

10H

z

SpectraPhysics Pro-350-101.4J,532nm@10HzSpectraPhysics Pro-350-10

1.4J,532nm@10Hz

25m

J@10

Hz

Evol

utio

n-30

20m

J@1k

Hz

Fara

day

isol

ator

Pock

els c

ell

¼ w

avep

late

Pock

els

cell

Gra

ting

IP 1

P 2

BBO

BBO H

WP

L 1L 2

Gra

ting

II

UV

Stre

tche

r

THG

Oscillator

Reg

enA

mp

To Compressor

To Photocathode

For future updating

BBO

BBO

HW

P

GTF

Sha

per

DA

ZZLE

R

TW Laser System Layout

Construction schedulePhase I 3TWPhase II 20TWPhase III 200TW

Design parameters for phase IICentral wavelength 800nmPulse energy >600mJPulse duration 30fsRepetition rate 10HzEnergy jitter <2%rmsDuration jitter <2%rmsBeam quality(M2) <1.5Beam size jitter <2%rmsPointing jitter <15μradContrast ratio 107@1ns

106@100ps104@1ps

ApplicationsThomson scattering X-ray light sourcesAccelerate-based THz light sourcesLaser wakefield particle acceleration Other laser-matter interaction fields

3TW

20TW

200TW

4 TTX in Progress-Laser System

800nm, 3TW,30fs

266nm, 1mJ, 30fs

4 TTX in Progress-50MW RF Power Source

4 TTX in Progress-50MW RF Power Source

4 TTX in Progress-Installation of New RF Gun Finished

4 TTX in Progress-Installation of 3-m SLAC TW linac

• Tsinghua Thomson Scattering X-ray Source (TTX) is under construction now and will be ready for commissioning at the end of this year.

• Beam diagnostic technologies ( emittance, bunch length, energy spread, et al) have been developed and tested.

• Different kinds of MeV electron diffraction experiments have been done during TTX construction.

• Synchronization between electron bunch and laser pulse has been tested.

• A LESR is under design for TTX.

4 Summary

Thanks for your attention!

1 TTX- Mini SR

For the pulse mode, the transverse emittance right before the beam is dumped is 2.2x10-7m.rad, the energy spread is 0.3%.

1 TTX- Mini SR

As for the steady mode, the equilibrium transverse emittance is 1.2 x10-6m.rad, the equilibrium energy spread is 4.4%

The working point of the steady mode is (Qx;Qy) = (3:197;1:662), which is close to the 5th order resonance. The dynamics is greatly influenced by the node (3:211;1:685), which limits the vertical DA. Moreover, the 5th order resonance may be further excited by the magnet errors. Nevertheless, the DA horizontal size is sufficient for the steady mode.

1 TTX- Mini SR