Laser chain

Laser chain

1) Present status of the laser for PHIN &CALIFES photo injector Achieved vs Target results

2) Preliminary results from the last PHIN photo injector3) Conclusion

e-

OUTLOOK

CLIC workshop Massimo Petrarca CERN 2009

AMP13-pass Nd:YLF

amplifier

AMP22 pass Nd:YLF

amplifier

Optical gate (Pockels cell)

Dt

24

Drive Beam (PHIN) & Main Beam (CALIFES)

Nd:YLF Oscillator 300mW

+ Nd:YLF Preamplifier

10W avg1.5GHz

400ms amplification window

250ms amplification windowUV

Dt Dt

Green

Dt

IR

Laser chain overview

Micro pulses at 1.5 GHz~666ps ~8ps

262nm 523nm 1047 nm

January 2008:no UV beam

commissioning of the laser to be done (… laser chain to be debugged)

December 2008: UV beam produced (not yet nominal energy)

1st run CALIFES & PHIN

September 2009:all laser main target parameters fulfilled !!!stable laser beam @ nominal energy sent to

cathode3rd CALIFES & PHIN runCLIC workshop Massimo Petrarca CERN

2009

CTF3 electron sources:

The same laser is used to drive two photo injectors:CALIFES for the generation of the “main beam”PHIN for feasibility study of the “drive beam” generation

D FFD

D F D

D F D D F D

D F D

DF DF DF DF DF DF DF DF DF

D F DF DF D

D FFFDD

D F DD F D

D F DD F D D F DD F D

D F DD F D

DF DF DF DF DF DF DF DF DF DFDF DF DF DF DF DF DF DF DF DF DF DF DF DF DF DF

D F DD F DF DF DF DF D

Drive Beam Accelerator

DL

Delay Loop:2

CR

Combiner Ring: x4

CLEX2 beams test area 100 MV/m

Drive Beam Injector thermionic gun

PHIN

From January 2008 in less than 1.5 year the laser has been settled up to a satisfactory condition for the commissioning of both the two photo injectors; During 2009, 30% of the time has been devoted to laser development


LASER target parameters for PHIN photo injector

distance between micro bunches ns 0.667

synch to external rf @ 1.5GHz ps <1

micro bunch width (FWHH) ps <10

micro bunch energy (@ cathode) nJ 370

laser pointing stability std mm 0.5

ok ok ok ok......

.

Laser

March 2009

Even though the target UV energy has been reached in March 2009 the available UV energy before was 2/3 of the nominal : enough for commissioning of the photo injectors

Laser

2.5 3 3.5 40

5

10

15

20

25

30Laser horizontal pointing stability

position [mm]

Eve

nt fr

eque

ncy

[a.u

]

3.5 4 4.5 5 5.5 60

10

20

30

40

50

60Laser vertical pointing stability

position [mm]

Eve

nt fr

eque

ncy

[a.u

]

s =0.16 mms =0.15 mm


LASER target parameters for PHIN photo injector


Synch to external rf @ 1.5GHz ps <1




ok ok ok okokOctober 2009

Stability laser effects on electron beam

0 100 200 300 400 500 600300320340360380400420440

Number of shots

Ener

gy (n

J)

Laser energy over 600 shotsavg ~ 369nJ/ micropulse on the cathode

1.3% RMS

Target: 0.25% rms (1%rms optional)

0 100 200 300 400 500 6000.3200000000000010.3300000000000010.3400000000000010.3500000000000010.3600000000000010.3700000000000010.380000000000001

Number of shots

Inte

nsity

a.u

.

Electron beam over 1000 shots

0.8% RMS

Current stability from the beam positioning monitors.

Preliminary

Retrieved energy measurement from integrated area of the laser beam profile picture @ virtual cathode; values are calibrated to the energy measurements by the Joule meter.


October 2009

Quantum efficiency

Preliminary


200 400 600 800 1000 1200 14001.8

1.851.9

1.952

2.052.1

2.152.2

2.252.3

QE vs laser train length

Train length (ns)

QE

(%)

old cathode

High Field Low Field

October 2009


0 200 400 600 800 1000 1200 14005

5.25.45.65.8

66.26.46.66.8

7

QE vs laser train length (av. 175 nJ on cathode)

Train length (ns)

QE

(%)

new cathode

Preliminary

Quantum efficiency

October 2009


PHIN:All the main LASER target parameters for PHIN photo injector

has been fulfilledMeasured Intensity Stability: <1.3% rms

can be lowered but it is already satisfactory for a laser without stabilization feedback

CALIFES: the laser has not been designed to produce the UV energy (~1mJ) required to obtain 0.6nC by 0.3% cathode QE. Nevertheless the amplification scheme can still be improved to get UV energy close to the nominal.

Summary for the LASER

Phase coding required for e-beam frequency multiplicationStabilization system to reduce the intensity fluctuationAmplification scheme higher ir energy Harmonic generation more UV energy

Future work

September 2009: +1 person on EN/STI/LP section to work on the laser welcome Marta Csatari !


DRIVE BEAM MAIN BEAM

UnitCTF3 / PHIN[17]

CLIC 3 TeV

CLIC Compton

ring

CLIC 3 TeV

m pulse charge nC 2.33 8.6 9.3 0.96m pulse width (FWHH) ps 10 12 100 100peak current A 233 716 93 9.6number of m pulses - 1908 92664 312 312distance between m pulses

ns 0.667 1.49 0.5 0.5

Macro pulse duration ns 1272 140000 156 156Macro pulse charge nC 4446 796900 3120 300

More powerful amplifiers can be added at this laser so that it can be used as a source for CLIC 3TeV “Drive Beam” if CeTe cathode with a QE of 3% is maintained.

For CLIC Compton ring: 2GHz laser oscillator is feasible but more powerfulamplifiers have to be designed if QE ~3% is maintained. Robustness of the cathode

must investigated

For the CLIC 3 TeV “Main Beam”The CTF3 laser scheme has to be reviewed in order to use cathode for polarized

electron generation like GaAs that work in range of wavelength different from the one offered by this laser ; other factors like the

peak current @ the cathode and its lifetime have to be investigated !!

Sur la route pour CLIC


AcknowledgmentLaser :

Nathalie Lebas (CERN, EN/STI/LP )Marta Csatari (CERN, EN/STI/LP )Valentine Fedosseev (CERN, EN/STI/LP section leader)Roberto Losito (CERN, EN/STI group leader)

2 months collaboration:M. Martyanov (Institute of Applied Physics, Nizhny Novgorod, Russia)G. Luchinin (Institute of Applied Physics, Nizhny Novgorod, Russia)V. Lozhkarev (Institute of Applied Physics, Nizhny Novgorod, Russia)

Photo injector:

Eric Chevallay (CERN, EN/STI/LP )Steffen Doebert (CERN, BE)Thibaut Lefevre (CERN, beam diagnostic group)Anne Dabrowski (CERN, beam diagnostic group)R. Roux (LAL; photo injector designer)


• We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 “Structuring the European Research Area” programme (CARE, contract number RII3-CT-2003-506395).

Acknowledgements


….. Oznur Mete


SPARES SLIDES


0 200 400 600 800 1000 1200 14000

0.5

1

1.5

2

2.5

QE for a fix field @ the cathode versus macro bunch length

macro bunch length

QE

%

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

-1-0.8-0.6-0.4-0.2

00.20.40.60.8

1

Position change in X (normalised to size) electron beam to laser beam

Normalized laser ‘’X’’ positionNor

mal

ized

e- ‘

X’ p

ositi

on-0.8 -0.4 0 0.4 0.8

-0.8

-0.4

0

0.4

0.8

Position change in Y (normalised to size) electron beam to laser beam

Normalized laser ‘’Y’’ positionNor

mal

ized

e- ‘

Y’ p

ositi

on

Stability laser effects on electron beam

Preliminary


Laser parameters :

…to fulfill PHIN photo injector requirements

micro bunches repetition rate ns 0.667





Micro bunches time structure


Laser parameters :

LASER target parameters to fulfill PHIN photo injector requirements






22 JNFJJ measreal Jreal ~ 634 fs (rms jitter required <1ps)

JNF: Jitter noise floor ~ 350 fs Jmeas: 724fs

Lecroy SDA (16GHz, 60GS/s+ NewFocus Photodetector25GHz)

Laser parameters :

LASER target parameters to fulfill PHIN photo injector requirements



micro bunch width (FWHH) ps 10



-15 -10 -5 0 5 10 150

0.5

1

Autocorrelation of IR amplified laser pulses

Time [ps]

Inte

nsity

[a.u

.]


FWHM~10ps ->7ps with considering deconvolution factor

Laser parameters :LASER target parameters to fulfill PHIN photo injector

requirements






200 400 600 800 1000 1200 1400290300310320330340350360370380

Laser pulse energy @ cathode

Bunch length (ns)

UV

pulse

ene

rgy

@ c

atho

de

(nJ)

no crystal angle adjustment performed

LaserLASER target parameters to fulfill PHIN photo injector

requirements






2.5 3 3.5 40

5

10

15

20

25

30Laser horizontal pointing stability

position [mm]

Eve

nt fr

eque

ncy

[a.u

]

3.5 4 4.5 5 5.5 60

10

20

30

40

50

60Laser vertical pointing stability

position [mm]

Eve

nt fr

eque

ncy

[a.u

]

s =0.16 mms =0.15 mm



IR 1047 nm



Laser chain

Documents

uv laser beam

stable laser beam

laser performances

laser target parameters

laser chainpresent status

laser main target parameters

phin califes photo injector

connection laser electron