ctf3 – status and plans

Frank TeckerCTF3 - IEFC Workshop 2012

CTF3 – Status and Plans

Frank Tecker – BE-OPfor the CTF3 team*

* Many thanks for all the material, esp. to R.Corsini

08/03/12

Highlights from 2011CLIC Feasibility DemonstrationPlans for 2012Running in 2013


CTF 3

CLEX

30 GHz “PETS Line”

Linac

Delay Loop – 42mCombiner Ring – 84m

Injector

Bunch lengthchicane

30 GHz test area

TL1

TL2

RF deflector

Laser

4A – 1.2µs150 MeV

32A – 140ns150 MeV

demonstrate remaining CLIC feasibility issues, in particular:

Drive Beam generation (fully loaded acceleration, bunch frequency multiplication)

CLIC accelerating structures

CLIC power production structures (PETS)

08/03/12


200 40 0 60 0 8 00 10 00

5 0

100

150

200

250

CLICtarget pulse

12 GHz RF power

135 MW

Power Extraction Structure (PETS)

P [M

W]

t [ns]

Many improvements on optics, hardware, feed-backs, beam stability, reproducibility…

PETS operation to power levels (~250 MW) well above CLIC goal, at nominal CLIC pulse length

Measured gradient in two-beam acceleration test 145 MV/m (CLIC nominal gradient of 100 MV/m)

Nine PETS tanks installed in the Test Beam Line (TBL), 20 A decelerated by ~ 25%, matching well with expectations

First successful test of PETS with on-off mechanism

First measurements of break-down kicks in TBTS

CTF3 Highlights - 2011

Test Beam Line (TBL) in CTF3

Two-beam acceleration in TBTS

Optics model checks in Combiner Ring

08/03/12


2011 ImprovementsGun pulse current flatteningAll RF phase sags made the same, including TWTs and MKS02Allowed for very quick setup of the factor 4 recombination in CR CTF3 Monitor: watches all signals stability, complete references, …FeedbacksIncreased recombined beam stabilityThe recombination is now much less vulnerable to drifts and jitters14A in CLEX, 13A routinely

08/03/12

Beam currentCombiner Ring4x combination


DL current

H

V

Problems: • TWT availability – still working with 2 (out of 3) SHB only

– plus day-to-day power fluctuations => Mainly working with 3 GHz beam for most of the year

• Difficult DL set-up after last stop – suspect misaligned quadrupole (+ radiation alarm problem)

Eventually able to get good recombination (current record), but:

• Bad pulse shape (phase switches?)

• Still limited acceptance -> stability was improved, but it is still not good enough

• DL quads measured and realigned

Future work:

• Work on phase switches, gun current compensation, back to 3 TWTs, improve trajectories

P. Skowronski

Drive Beam Generation – Factor 8

08/03/12t [ns]

I [A]


Repeatibility and long term current stability improved

Pulse charge stability measured at end of the linac better than CLIC requirements

P [M

W]

RF power feedback, MKS 13

Time [h:m]

Feedback on

Feedback off

Feedback on

Several feed-back loops operational, for temperature, RF phase and power and gun current.

G. Sterbini

Charge stabilityFactor 4

P. Skowronski, T. Persson

T. Perssons [m]

5 10-41 10-3

CTF3 Stability - Feedbacks

08/03/12


Beam recombination - Emittance

Best results in CLEX for factor 4: eH= 250 um eV= 140 umfor factor 8: eH= 640 um eV= 170 um

Different turns are ~ ok, no unknown effectsEmittance increase due to non perfect combination

• Improve measurements• Correct dispersion (linear, nonlinear)• Correct multi-turn orbit• Control RF deflector bump

2012

Horiz. Vert.

Measurements in TL2 - uncombined

Uncombined beam

Drive Beam Generation - Emittance

08/03/12

Nor

mal

ized

rms e

mitt

ance

(mm

mra

d)


TBL – Test Beam Line Decelerator

Drive beam has high current and gets high energy spreadStable transport in simulations verified experimentally with 9 PETSno losses in TBL, optics understoodSo far 19 A beam decelerated by ~25%, 0.5 GW power produced!Good agreement of power production, beam current and deceleration

08/03/12

9 PETS – 19 ANovember 2011

Steffen Doebert, Reidar Lillestol

TBL line in CLEX


PETS operated routinely above 200 MW peak RF power

providing reliably pulses ~ 100 MW peak to accelerating structure.

About twice the power needed to demonstrate 100 MV/m acceleration in a two-beam experiment with TD24 structure.

2 00 4 00 60 0 80 0 1 00 0

5 0

10 0

15 0

20 0

25 0

CLICtarget pulse

12 GHz RF power in PETS

135 MW

P [M

W]

t [ns]R. Ruber, I. Syratchev

Two-Beam Test Stand (TBTS) – power production

08/03/12


TD24

Drive beam OFF

Drive beam ON

Achieved Two-Beam Acceleration

Maximum probe beam acceleration measured: 31 MeV Corresponding to a gradient of 145 MV/m

08/03/12


ONOFF

PETS outputTo Structure input

(as predicted by computer simulation)

TBTS PETS layout with internal recirculation to test the ON/OFF concept

Movable RF short circuit (to tune the resonant length)

Variable reflector (to tune the recirculation coupling)

Igor Syratchev

PETS ON/OFF mechanism in TBTS

08/03/12


Simulation vs. experiment

0N

0FF

Combination x 4 0N

0FF

0N

0FF

Beam current PETS, forward RF

RF to structurePETS, reflected RF

Signal evolution during On-Off

Igor Syratchev, Alexey Dubrovskiy

PETS output, forward

PETS On-Off mechanism - results

PETS on-off principle fully tested

Conditioned at high power (135 MW - nominal) by recirculation08/03/12

PETS

1

2

3

1

3

2


Bunch length control < 1 mm rms (end of linac)

Full beam loading (95% transfer) high current acceleration (up to 5 A)

Ring isochronicity ap < 10-4

Sub-Harmonic bunching with fast (< 6ns) 180 phase switch(8.5% satellites)

Control of ring length to better than 0.5 mm

Factor 2 combination in Delay Loop (from 3.5 to 7 A)

Bunch train recombination factor 4 in Combiner Ring (from 3 to 12 A)

Beam current stability ~ 0.1 % end-of-linac,~ 0.2 % combiner ring

Transverse rms emittance 100 p mm mrad (end of linac)

Bunch train recombination 2 x 4 in DL and CR (from 3.5 to 28 A)

Transverse rms emittance < 150 p mm mrad (combined beam)

Bunch length control < 1 mm rms (combined beam)

Beam current stability ~ 0.2 % for fully combined beam

CTF3 Achievements – What is still missing for feasibility – Drive Beam Generation

~ 0.05 % end-of-linac !

13

~ 0.1 % factor 4~ 0.1% factor 2 after DL

~ 1 %

DB generation , 2012:

Improve beam quality for factor 8 beam (emittance, bunch length, stability)

CTF3 Achievements – Drive Beam

08/03/12


Beam-powered test of a PETS with external recirculation to 170 MW, <200 ns - ~10 A beam currentPower & drive beam energy loss measurements.

CTF3 Achievements – What is still missing for feasibility – TBL / TBTS

Beam-powered test of a PETS to nominal parameters (135 MW, 240 ns) with external recirculation (10 A) and without (20 A) – including probe beamImproved power & drive beam energy loss measurements

Break-down kick measurements

PETS On-off mechanism demonstration

Drive beam phase 2012/2013

8 (12 > 16) PETS + spectrometer installed to verify transport of a 28 A beam with up to 30% of energy extracted.

Probe beam acceleration to 100 MV/m. (up to 145 MV/m measured)

14

9 PETS20 A beam25% deceleration

TBL:

• 12 PETS start 2012

• 16 PETS in 2013 (TBL+)

TBTS, 2012:

• Continue studies with two new structures

• Wakefield monitors

CTF3 Achievements – Two-Beam issues

08/03/12


CTF3 in green colour

Technical system tests and

simulations

RF Test StandsSLAC – KEK -CERN

System Item Feasibility Issue Unit Nominal Achieved How Feasibility CommentsFully loaded accel effic % 97 95 CTF3 Freq&Current multipl - 2*3*4 2*4 CTF3Combined beam current (12 GHz) A 4.5*24=100 3.5*8=28 CTF3 Combined pulse length (12 GHz) nsec 240 140 CTF3Intensity stability 1.E-03 0.75 < 0.6 CTF3 End of DBA. To be demonstrated for combined beam in 2011Drive beam linac RF phase stability Deg (1GHZ) 0.05 0.035 CTF3, XFEL Achieved in CTF3, XFEL designPETS RF Power MW 130 >130 TBTS/SLAC PETS Pulse length ns 170 >170 TBTS/SLACPETS Breakdown rate /m < 1·10-7 ≤ 2.4 10-7 TBTS/SLACPETS ON/OFF - @ 50Hz - CTF3/TBTS 2011 Prototype under fabrication for tests with beam Drive beam to RF efficiency % 90% - CTF3/TBL

2012TBL with 8 (16) PETS in 2011(12) for 30(50%) efficiency. Benchmark beam simulation for safe extrapolation of high efficiency at high drive beam energy(2GeV).

RF pulse shape control % < 0.1% - CTF3/TBTS 2011-2012Structure Acc field MV/m 100 100Structure Flat Top Pulse length ns 170 170 Structure Breakdown rate /m MV/m.ns < 3·10-7 5·10-5(D) 2011Rf to beam transfer efficiency % 27 15 2011

Power production in Two Beam Test Stand (TBTS) Probe beam acceleration by Two Beam Test Stand(TBTS)

Drive to main beam timing stability psec 0.05 - CTF3 2012Main to main beam timing stability psec 0.07 - XFEL? 2012Emitttance generation H/V nm 500/5 3000/12 Damping Ring design nom perf. Relax emitt achieved ATFEmittance preservation: Blow-upH/V

nm 160/15 160/15 2011-12 Simulation + alignment/stabilityMain Linac components microns 15 2011Final-Doublet microns 2 to 8 2011Quad Main Linac nm>1 Hz 1.5

Final Doublet (assuming feedbacks) nm>4 Hz 0.2drive beam power [email protected] beam power of [email protected]

Operation and Machine Protection System (MPS)

CTF3 simulations 2011 Report integrating LHC experience under preparation

Principle demonstrated in CTF2, to be adapted to long distances and integrated in Two Beam Module in 2010

Vertical stabilisation

0.13 (principle)

Stabilisation Test Bench 2011-12 Adaptation to quad prototype and detector environment in

2010. Integrated in Two Beam Module with beam till 2012.

2011

Ultra low beam

emittance & sizes

Ultra low Emittances

ATF, NSLS/SLS + simulation

Alignment 10 (princ.) Alignement & Mod.Test Bench

Two Beam Acceleration

Power producton and probe beamacceleration in Two beam module MV/m - ns 100 - 170 106 - 170 TBTS

Two Beam Acceleration

Drive beam generation

Accelerating Structures

(CAS)

CTF3 Test Stand, SLAC,

KEK

Nominal performances of 3 structures without damping. 1 structure equipped with damping features under RF conditionning to reduce breakdown rate.

Novel scheme fully demonstrated in CTF3 in spite of lower current since beam dynamics more sensitive than nominal

due to lower energy (250MeV/2Gev)

Beam Driven RF

power generation

BD rate at nominal power and pulse lenght, measured on Klystron driven PETS. Beam driven tests under way in CTF3

CLIC Feasibility Benchmarks

08/03/12


Main goals for 2012Improve beam quality: emittance, beam current (losses), bunch length, reproducibility, long & medium term stability, current & phase jitter – especially for factor 8

- It’s a goal in itself, but will also ease all other experimental goalsImprove existing feedbacks, develop & deploy new onesincrease beam repetition rateCorrect/cross-calibrate BPMs, improve DB phase diagnostics (BPRs, phase monitors)

TBTSPETS on/off:

Measure break-down rates in different conditions (recirculation high-power, nominal on and off)New accelerating structure with wakefield monitorsBD measurements & BD kicks measurements, wake-field monitor testsRF pulse shaping tests

TBLRF power production: 12 to 13 PETS tanks, from 20 A to 30 Afurther improve precision of current, energy, bunch length & RF power measurementsReach more than 1/3 decelerationDrive beam phase stability monitoring

TERA run for medical accelerator testPHIN photoinjector tests

08/03/12

Frank Tecker

2012/13 - BDR with beam loading

Beam loading reduces field => BDR lower?CLEX probe beam has only low current=> use CTF3 drive beam and klystron driven X-band structurereactivate the old ‘30 GHz PETS’ line

CLEX

DRIVE BEAM LINAC

DELAY LOOP

COMBINER RINGBL - BDR

experiment


CTF3 plans for 2013+ - TBL+12 PETS installed start 2012Improve Drive Beam quality for combination 8in 2012 (emittance, bunch length, stability)Study deceleration, power production, and beam stability16 PETS installed late 2012

Upgrade TBL to a test facility relevant for CLIC TDR work

12 GHz power production for structure conditioning and component testingWorking experience with a real deceleratorBeam dynamics studies, pulse shaping, feedbacks, etc.

Timeline:Last batch of four PETS installed in late 2012 will be adapted to high-power testingOne (or two) slots tested at beginning of 2013Gradual increase to 4-8 slots and higher rep rate

08/03/12

PETS tank

Accelerating structure under test Beam

RF

S. Doebert


CTF3 plans 2013+ - Two-beam modulesTests of a series of full-fledged Two-Beam Accelerator modules with beamTests of RF, beam instrumentation, cooling, alignment, etc. in real accelerator environmentFirst module in CLEX TBTS in 2013Three modules types foreseen for 2014

08/03/12

3D model of integration of the first CLIC Module in CLEX (2013)

CLEX - Three two-beam modules(2014)

G. Riddone

Schematic layout of T0 module

Drive beam

Probe beam


Phase monitor

DRIVE BEAM LINAC

CLEXCLIC Experimental Area

DELAY LOOP

COMBINERRING

10 m

Phase & energy measurement

Fast feed-forward kicker in final

compression line

CTF3 - Phase feed-forward

Phase monitor

Stripline kicker

P. Skowronski,P. Burrows, A.Ghigo

Fast kickers

CLIC drive beam phase feed-forward concept

Drive Beam feed-forward and feedback

Show principle of CLIC fast feed-forwardSeries of related studies at CTF3 to measure phase and energy jitter, identify sources, devise & implement cures, extrapolate to CLICPhase monitor tests in 2012First feedback/feed-forward tests in 2013Close link to collaborating partners(INFN, Oxford…)

08/03/12


2013 - CTF3 operation wish listBeginning March: water, electrical systems, CO, etc. for HW testsBeginning April: start with beamMid December: Beam stop

During operation CTF3 normally uses the resources of:Piquet ControlFirst line PO

Both not absolutely essential for CTF3 operation (at expense of efficiency) Best effort service from specialist has been done for limited time in the past

RP controlsAccess control

Discussion started how this can be doneCCC for night and weekend supervision

Can be droppedOccasionally EN/CV for water stations and some vacuum support

08/03/12


SummaryVery good progress in 2011 through many improvements

>250 MW produced in PETSup to 145 MV/m acceleration19A beam decelerated by ~25%, >0.5 TW RF power producedPETS ON/OFF mechanism verified

Main goals in 2012improve beam quality in particular for factor 8 combinationdeceleration studies with 12/13 PETS in TBLBreakdown rate measurements for PETS ON/OFFAccelerating structure test with wakefield monitors in TBTScontinue breakdown kick and breakdown rate studies

Further planningincrease beam energy and repetition ratemeasure breakdown rate with beam loadingstudy CLIC two-beam modulesupgrade TBL to an RF testing facilityimplement a phase feed-forward for the drive beam

08/03/12

ctf3 – status and plans

Documents