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COMMISSIONING of the ALBA LINAC M.Pont XVI ESLS 27-28 November 2008. SCHEDULE. 10/2005 Contract signed with THALES Communications (turn-key system) 09/2006 Design report approved 10/2007 Linac ready at THALES ….. CELLS building not ready for installation

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Commissioning of the alba linac m pont xvi esls 27 28 november 2008

COMMISSIONING of the ALBA LINAC

M.Pont

XVI ESLS

27-28 November 2008


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

SCHEDULE

10/2005 Contract signed with THALES Communications

(turn-key system)

09/2006 Design report approved

10/2007 Linac ready at THALES

….. CELLS building not ready for installation

02/2008 Linac installation at CELLS

…. Additional waiting for conventional facilities

05/2008 Start conditioning

07/2008 First beam

10/2008 Site Acceptance Tests



Commissioning of the alba linac m pont xvi esls 27 28 november 2008

Main components:

  • Electron Gun : Thermionic (Pierce type), 90 kV DC gun with grid modulator at 500 MHz

  • Bunching Section: Pre-buncher: single cell @ 500MHz

  • Pre-buncher: single cell @ 3 GHz

  • Buncher: 1 SW bunching section @ 3GHz

  • Energy at the bunching section output = 16 MeV

  • 2 Acc. sections: TW 2/3πConstant Gradient3 GHz.

  • Energy gain= 55 MeV @ 20MW nominal input power.

  • 2 Klystron modulators: 35 MW each klystron at 3GHz.

  • The first one feeds the 3 GHz bunching section and the 1st acc. structure.

  • The second one feeds the second accelerating structure

E-gun electronics

Buncher

Accelerating structure

klystron



Commissioning of the alba linac m pont xvi esls 27 28 november 2008

E-gun

500 MHz pre-buncher

Service Area

1st accelerating structure

Cooling loop


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

LT installation done by CELLS

FCUP

(Beam Dump)

to Booster

SCR

FSOTR2

BCM2

FCT-LiDia

Diagn. Line

(LiDia)

FSOTR1

BPM2

AE

Vac. Valve

(Linac End)


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

Conditioning started May 08

After 3 weeks of conditioning

P = 32.5 kV POUT = 29.10 MW

V = 244 kV PAS1 = 17.60 MW

I = 249 A Pbuncher = 5.20 MW

  • Requeriments for a 100 MeV beam

    • PAS1 = 15 MW

    • Pbuncher = 5 MW

    • PAS2 = 10 MW

AS1

AS2

POUT = 18.0 MW

PAS2 = 16.7 MW

  • Break down, no recovery

  • At last window broke

  • Fast replacement thanks to SOLEIL

Buncher focusing ON

1 Hz

3 Hz


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

FIRST BEAM IN THE LINAC

02.07.08

Q=0.2 nC

Pulse length 240 ns


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

FCT4

AE

Li-BPM

LT-BPM

FIRST BEAM IN THE LT

03.07.08

FCT1

FCT2

FCT3


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

PULSES: Time characterisation

SBM, 2 nC in 8 pulses (zoom on 1st pulse)

4 % amplitude reduction

420ps

specs <1ns

Jitter: 28 ps (rms)

Specs < 100 ps (rms)


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

Energy and energy spread

Bending

Linac

SCRH

BCM2

BCM1

  • Energy scan through bending magnet or scraper offset

  • Log BCM ratios (before and after bending)

Plotting BCM ratio vs energy provides E0 and DE/E0:

E

MBM DE/E0 = 0.2 %

SBM DE/E0 = 0.3 %

FWHM


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

Beam optimisation at 108 MeV, MBM

Beam loading compensation to reduce the energy spread

The beam is injected during the filling time of the 2nd structure

Measured energy spread is

1.55 MeV FWHM (no beam loading comp.)

After using beam loading compensation

New energy spread is 0.5 MeV FWHM

Beam loading compensation allows for a reduction of the energy spread by a factor 3


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

Emittance measurements

FS/OTR

Q triplet

Linac

  • Scan one Q (usually Q1) around a beam waist at FS/OTR

  • Record beam size vs Q strength

  • YAG FS vs OTR

  • Online & offline analysis

Typical fitted beam profile


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

Emittance measurements

MBM, 112 ns, 3.8 nC, 106.5 MeV

OTR screen


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

RESULTS OF SAT

* Beam dynamics optimised

** Limited by instrumentation noise

*** Operation at 5 Hz is not required (Booster runs at 3 Hz max)


Commissioning of the alba linac m pont xvi esls 27 28 november 2008

CONCLUSIONS

  • The tests on the Linac have been very succesful

  • Specifications achieved in the different operation modes: SBM and MBM in terms of charge, energy spread and emittance

  • Final Acceptance to be signed before end of the year (waiting for the final documentation)

  • After restarting the Linac in spring 2009 more measurements are needed in order to fully characterize the beam (improve transmission, look for max E achievable, re-measure emittance …)