Drive Beam Generation in CTF3S. Bettoni (CERN) for the CTF3 commissioning team

Talk outlineDrive beam manipulation:o Combiner ring (factor 4)o Delay loop (factor 2)o Delay loop AND combiner ring (factor 8)

Beam delivery to CLEX

Conclusions

CTF3 for CLIC

fully loaded acceleration

recombination x 2

phase-coding

bunch length control

recombination x 4

bunch compression

PETS on-off

two-beamacceleration

structures 12 GHz

structures 30 GHz

deceleration stability

StructuresStructure materialsDrive Beam generation PETS on-offDB deceleratorCLIC sub-unit

CTF3 is a small scale version of the CLIC drive beam complex: Provide the RF power to test the CLIC accelerating structures and components Full beam-loading accelerator operation Electron beam pulse compression and frequency multiplication Safe and stable beam deceleration and power extraction High power two beam acceleration scheme

Achievements in the past

Beam routinely sent during the week-ends to the PETS structures

MKS03 MKS07MKS06MKS05 To the rings

To the 30 GHz test stand

Measured RF to beam efficiency: 95.3 %

Expected from the theory: 96%

The status of the machine up to CLIC08: Provide the RF power to test the CLIC accelerating structures and components (since 2005)

Full beam-loading accelerator operation (since 2004)

Electron beam pulse compression and frequency multiplication (since 2006)

RF pulse with beam

RF pulse without beam

Analog signal

*AFTER THE CURE OF THE VERTICAL INSTABILITY IN THE RF DEFLECTOR, D. ALESINI (LNF) ET AL.

*

CTF3 operation scenarios

DBA CRDL

TBTSCLEX

CTF3

CTF2

#1

<30A

#2

CRDL

CTF3

14 ACLEXCTF2 TBTS

#3

CRDL

CTF3

4 ACLEXCTF2 TBTS

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

Delay loop: the recombination

0 500 1000 1500 2000 2500

6

4

2

0

t [ns]

I [A

]

2007

Delay loop: improvement of the recombination

ONGOING

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

PUT A COUPLE OF 180º PHASE SWITCHES IN THE TRANSIENT PART OF THE TRAIN

THE FIRST PHASE SWITCH INTRODUCES DIFFERENT

LOADING

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

Delay loop: current stability

CL.SVBPM1590S CT.SVBPM0515S Min. (A) -3.858 -6.300 Max. (A) -3.828 -6.234 Mean (A) -3.845 -6.277 Std (A) 0.007 0.014

Variation (%) 0.17 0.22

Through DLBy-passing DL

Delay loop: control of the optics

Delay loop optics:

Control of the optics enough to have successful recombination (betas and dispersion)

Small adjustments (order of %) necessary to have full transmission (worse for the model):o Identified regions of model/machine discrepancies by means of kick measurements

The optics is quite transparent for the beam

Combiner ring: the recombination

2008

Combiner ring: current stability

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

Combiner ring: control of the optics

20 21 22 23 24 250

0.2

0.4

0.6

0.8

1

IQ560 (A)

Frac

tiona

l par

t of t

he tu

nes

Qx (measured)

Qx (simulated)

Qy (measured)

Qy (simulated)

0 20 40 60 80 100

-0.5

0

0.5

1

s (m)

Dx (m

)

Model (at BPM only)Model (all the elements)Measurement

To validate the MAD-X model of the combiner ring: High precision kick measurements compared to the model predictions:

o Symmetric kick analysis to identify single quadrupole erroro Multi-turn analysis to magnify the effect of the discrepancy

Other independent measurements are used to check the correction:o Dispersiono Tunes

TURN 1 TURN 2 TURN 3

P. Skowronski

The status of the machine up to CLIC08: Provide the RF power to test the CLIC accelerating structures and components (since 2005)

Full beam-loading accelerator operation (since 2004)

Electron beam pulse compression and frequency multiplication (2009)

NowAchievements in the pastThe status of the machine up to CLIC08:

Provide the RF power to test the CLIC accelerating structures and components (since 2005)

Full beam-loading accelerator operation (since 2004)

Electron beam pulse compression and frequency multiplication (2006-present)

Delay loop & combiner ring: THE recombination

ONLY DL

ONLY CRDL & CR

New lines installed in 2008/2009

42.5 m

8 m

2m

D FFD

DF

F

D F DDUMPD F D

F

FD

ITB

1.85m

CALIFES Probe beam injectorLIL-ACSLIL-ACSLIL-ACSD F D

D F D

DFDUMP

0.75

1.4m

1

DUMP

22.4 mTBL

2.5m

Transport path

DUMP

DUMP 22 m2.0m

DF DF DF DF DF DF DF DF

3.0m3.0m6 m

D F DF DF D

16.5 mTBTS16 m

TL2’

42.5 m42.5 m

8 m8 m

2m2m

D FFFDD

DF

FDD

FF

FF

D F DD F DDUMPD F DD F D

F

FD

F

FD

F

FD

ITB

1.85m1.85m

CALIFES Probe beam injectorLIL-ACSLIL-ACSLIL-ACSLIL-ACSLIL-ACSLIL-ACSD F DD F D

D F DD F D

DF DFDUMP

0.75

1.4m1.4m

11

DUMP

22.4 m22.4 mTBL

2.5m2.5m

Transport path

DUMP

DUMP 22 m22 m2.0m2.0m

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

3.0m3.0m3.0m3.0m6 m6 m

D F DD F DF DF DF DF D

16.5 m16.5 mTBTS16 m16 m

TL2’

DRIVE BEAM LINAC

Injector

CLEX

30 GHZ test stand

30 GHz power station

DELAY LOOP

COMBINERRINGchicane

TL1

TL2

probe beam linac

two-beam test stand

TBL - decelerator

CTF3 – Main components

New lines installed: TL2 → transfer line from CR to the CLEX area CLEX area:

o TBL → study the drive beam stability during the decelerationo TBTS → test the two-beam acceleration schemeo CALIFES → probe beam linac

RRCAT

Module-1 Horizontal achromat

Module-3 Tunable R56 (from -0.35

to +0.35) Achromatic arc Final matching doublet

Module-2 Straight section for tail

clipper Vertical achromat Matching section

Going to CLEX

3x

4x

TWISS PARAMETERS FOR THE DIFFERENT EXTRACTED TURNS QUITE SIMILAR

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

Transfer line 2: control of the optics

CR

TL2

Steps of the commissioning: New MTV monitor installed in the line during the 2008/2009 winter shut down Commissioning made more difficult by the BPM not working properly yet (work in

progress) Uncombined beam transported almost to the end of the line, combined with more

losses Kick measurements evidenced two regions where the model and the machine don’t

agree (check on the two identified quadrupoles this week)

CR combined beam

Uncombined beam

The control of the orbitIn CTF3 the control of the orbit is more critical than in other machines:

The efficiency of the recombination depends on the ring length The subpulses which go through the DL must be put on top of the ones which go straight The orbit of the recombined subpulses in the CR is the superposition of more orbits The closure of the orbit in the CR is crucial also for the transport of the recombined beam

Input: Maximum tolerance Maximum strength of the correctors Response matrix measured or from the model (CR)

111

1

1

1

1

,, yxI

I

yIorbitV

I

xIorbitH

j

kk

j

kkk

jTurn

j

kk

j

kkk

jTurn

measured

ONGOINGInput:

Maximum tolerance on:o The orbit difference o The overall orbit excursion

Maximum strength of the correctors

CTF3 reliabilityFully loaded operation mode + RF compression don’t make CTF3 reliable “for free”:

Orbit references (Indian collaboration)

RF loading and beam current references (tool to do it automatically to be tested)

Phase loop (A. Dubrovskiy, CERN)

ConclusionsSEVERAL OF THE CTF3 GOALS HAVE BEEN ALREADY DEMOSTRATED IN THE PAST YEARS:

Fully loading operation mode (consistent with theory predictions) First demonstration in delay loop

2009 MILESTONES: Successful factor 4 recombination achieved Successful factor 2 recombination in delay loop obtained Factor 2x4 recombination putting in operation delay loop AND combiner ring Beam through PETS in the CLEX area

FUTURE SHORT TERM PROGRAMS: Improve the reliability and the stability of the machine Further optics studies in the delay loop and in the new lines Test of the two beam acceleration scheme in CLEX (acceleration and stability studies)

SPARE SLIDES

Measurements in TL2

CC.QDH0220 = -23 %CC.QFL0530 = +20 %

Delay loop: fast phase switch & satellites

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

666 ps

1 8

Streak camera image

mainsatellite

Fast phase switch from SHB system

Gap creation and x2 multiplication

odd buckets

even buckets Delay

Loop

RF deflector

Combination scheme

Ldelay = n l0 = c Tsub-pulse Phase coding

180 phase switch

Acceleration n0

Deflection n0 / 2

Sub-Harmonic Bunching n0 / 2

How to “code” the sub-pulses

Combiner ring multiplication

3rd

lo/4

4rd

2ndinjection line

septum

localinner orbits

1st deflector 2nd deflector

1st turn

lo RF deflector field

Fully loaded operation mode

Lstruct

loaded

Gacc

s

unloaded

E0

t

tfill

steady state E0 /2

Ebeam

400300

-5

0

5

time (nsec)

P/P (%)

P1050Central =107.5MeV/c

-50

5

600

700

800

900-10-5

05

10-1

-0.5 0 0.5 1

P/P (%)

Ppeak =108.5 MeV/c, PFWHH =11.68%

600700

800900

0 1 2 3 4 5

IBeam (A)

time (nsec)

600700

800900

108

110

112

Ppeak (MeV/c)

time (nsec)600

700800

9001 2 3

PFWHH (%)

200100

Transient

Steady stateP/P

(%)

Time (ns)

Time resolved beam energy spectrum measurement in CTF3

THE recombination: current stability

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

4 A – 1.2 ms150 Mev

32 A – 140 ns150 Mev

CL.SVBPM0502S CT.SVBPM0515S CR.SVBPM0155SMin. (A) -4.085 -5.322 -25.585Max. (A) -4.067 -5.280 -24.255Mean (A) -4.078 -5.308 -25.210Std (A) 0.005 0.011 0.254

Variation (%) 0.13 0.20 1.01

FIRST MEASUREMENT

(NOT BEST CONDITIONS)

THE END