PoS(EPS-HEP2017)537 https://pos.sissa.it/ * ´ nski Roberto.Corsini@cern.ch [email protected] Speaker. The CLIC Test Facility (CTF3)acceleration was scheme. built The to main demonstrate issues the tousing be feasibility a verified of fully were the loaded the CLIC highly high current efficientRF two drive deflectors, linac beam beam to and generation increase a beam beam current combination andused bunch for scheme, repetition GW based frequency. level on The RF drive transverse power beam productiona has and test been two ground beam for acceleration development experiments. of CTF32016 many was and accelerator also in technologies. this Its contribution operationaccelerator the was physics concluded results community will in relevant be for presented. the CLIC design as well as for the whole * © Copyright owned by the author(s)Attribution-NonCommercial-NoDerivatives 4.0 under International the License terms (CC of BY-NC-ND the 4.0). Creative Commons The European Physical Society Conference on5-12 High July, Energy 2017 Physics Venice CERN, Geneva, Switzerland E-mail: Piotr K. Skowro Roberto Corsini CERN, Geneva, Switzerland E-mail: Lessons from CTF3 PoS(EPS-HEP2017)537 ) 1 ´ nski Piotr K. Skowro ]. It consisted of a 150 MeV 1 RF power is produced by decelerating ]: 2 1 CTF3 tested a novel technique based on fully-loaded Schematic CTF3 layout. Figure 1: the drive beam intures). dedicated Using cavities waveguides called it PETS100 is MV/m. (Power delivered to Extraction Deceleration studies accelerating and wereLine structures Transfer (TBL) performed operating in Struc- using CTF3 at a experimental gradient area string of (CLEX). of Alternatively, the PETS drive in beam the was Test delivered Beam Efficient production of high-current electronfor drive 12 beam GHz with RF time power structure production. suitable RF power production and two-beam acceleration. acceleration in normal conducting travellingbunch wave frequency structures multiplication followed in by a beam seriesthis current way of and a delay 28 lines A and electron rings. beam with CTF3 12 was GHz producing bunch in repetition frequency. The CTF3 studies can be divided into two categories [ The CLIC International Collaboration built at CERN the CLIC Test Facility CTF3 (see Fig. 1. 2. in order to prove feasibility of the two-beam acceleration technology [ Lessons from CTF3 1. Introduction electron linac, 42 m long Delayflector Loop the delay (DL) loop and was a interleaving the 84ble 1120 m ns current, Combiner beam which pulse Ring were to (CR). produce combined With four intobeam help 140 single of ns was pulses 140 RF delivered of ns de- to dou- pulse the by12 CLIC the GHz combiner experimental RF ring. area power (CLEX) The accelerating recombined injector where a (Concept it d’Accélérateur probe was Linéaire beam. decelerated pour to Faisceauxin The produce d’Electrons the probe same Sondes, area. beam CALIFES) located was generated with a 200 MeV PoS(EPS-HEP2017)537 2 ]. 5 RF ´ nski ◦ Piotr K. Skowro 2 ]. 6 ]. A streak camera at the end of the linac measured a bunch length of 1 mm [ phase switch. The switching time is less than 6 ns (eight 1.5 GHz periods), which 4 ◦ ]. SHBs were 6-cell travelling wave (TW) structures with a nominal power of 40 kW. 3 to another beam line called Two(TBM), Beam Test where Stand one (TBTS) renamed or later200 more Test MeV Beam PETS electron Module beam powered provided one by CALIFES. or more structures, further accelerating a The optimization of the transverse emittance, the bunch length and the satellite population was The overall efficiency is one of the key parameter of linear colliders. Full beam-loading opera- CTF3 was constructed and commissioned in stages. The linac started operation in 2003, the The drive beam injector consisted of a thermionic gun delivering up to 10 A beam, three carried out by means ofoptimized exhaustive to PARMELA keep simulations. the emittance Themeasurements at magnetic [ the field exit distribution of was the injector below 50 µm, which was confirmed by tion is one of the key pointsto in the the drive CLIC design beam. because it Ittravelling-wave yields RF is a structures achieved very with by efficient relatively RF the low energy acceleration gradient. transfer of When a the beam high is beam present current in (about the 4 cavity A) by short phase switches. Following, a 3create GHz the single-cell final bucket pre-buncher structure and2 and a cm accelerate long TW pre-buncher the buncher was 100 beam were kW, while up installed for to to the half-meter ~6 long MeV/c. buncher it The was maximum nominal 40 power MW. of Some electrons were forming unwanted satellitemeasured bunches fraction in of between the the satellites main was 1.5 GHz about ones. 8%, The compared to the design value ofis well 7%. below the Figure 10 ns target [ 2.2 Linac - Full Beam-Loading Acceleration presents a projection of a streakduring camera the image 180 that shows the bunch population in function of time They generated the initial energy-time modulation and phase coding by means of fast 180 delay loop in 2006 andcluding the the CALIFES combiner injector, ring and inRecombination the the with transfer the following line DL year. and from CRof the In together combiner beam 2009 was ring current. achieved CLEX in were beam In autumn commissioned. lines,beam of 2010 2009 in- test the yielding was PETS up performed, started to 28 producing reachinggradient A the a of nominal measured 145 power gradient MV/m level ofsuccessfully was and 100 tested. the reached MV/m. A first in 2 two- m 2011. Ultimately,Module, long accelerating fully TBM, The representative replaced unit same the of year the TBTSby the CLIC at 50% main PETS of the linac On-off its end called initial mechanism Two-Beam ofwere energy. was 2014. continually The improved Drive In after beam 2015 the stability TBLlast initial and years decelerated commissioning, the of until the overall operation performances the drive CTF3 of final beam hostedthe the run several initial facility additional in planning. experiments 2016. and Most During beam of tests the them that - were but not not in all - were2. CLIC related. Drive Beam generation 2.1 Injector - Beam Current and Time Structure 1.5 GHz sub-harmonic bunchers (SHBs)buncher and [ a 3 GHz system composed of a pre-buncher and a Lessons from CTF3 PoS(EPS-HEP2017)537 ´ nski ]. The large 7 3 mode. They 10 µm confirm- / π ≈ Piotr K. Skowro ]. As predicted by y , 8 x ε 3 pulses and over 60 MW. The pulse compression system uses a s µ 3 . Fast bunch phase switch, measured by a streak camera. At the top the 1.5 GHz periods are shown. The design beam current and pulse length were rapidly established during beam commission- The beam-to-RF phase was adjusted by maximizing the beam loading. It was achieved by average current leads to pronounced effectsbe of damped transverse higher in order order modesSlotted to (HOMs). Iris avoid They must beam - instabilities Constant Aperture andirises (SICA) that emittance are structures growth. radially were slotted Dedicated designedmodes to cavities for are guide selected called this dipole through purpose. their and field quadrupolebelow distribution, They modes 20), strongly feature into damping while the SiC monopole HOMs loads. modes (Qditional are factor The typically not HOM damped influenced. detuning Nose along conesgroup the of velocity structure. to variable control geometry the This yield gradient improves ad- structure profile. their short Thanks range to suppression wake-fields the and are aperture modulates reduced. thatklystrons is the The providing kept structures 5.5 constant were along µs powered the RF bypulses 35 pulses. were MW compressed to Each to 45 1 unit MW was powering 2 accelerating structures and the simulations the normalized emittance at the end of the CTF3 linac was about ing in June 2003.at The high beam current. was remarkably It stable proved for and the no first sign time of the beam fully break-up loaded was beam observed operation [ minimizing the RF amplitude observed at the structure output couplers. The acceleration efficiency no RF power is transmitted toof the the load CLIC and structures the an resistive overall losses efficiencythe of in pulse about the 98% there walls is is are achieved. minimal. an However, atof energy In the the the transient beginning case steady-state effect, of part. such that This thethe mode first of beam bunches operation energy. may also The have strongly CTF3 twice coupleswere the beam 3 1.22 current energy GHz m fluctuations long TW to and accelerating operated structures at worked a in loaded the gradient 2 (nominal current) of 6.5 MV/m [ programmed phase ramp to provide a constant RF power. ing negligible effects of the wake-fields.could The also energy be spread reduced to of a the few initial percent beam by transient partial (~100 RF ns) filling of the structures at beam injection. Figure 2: Lessons from CTF3 PoS(EPS-HEP2017)537 ) ´ cm nski 1 | ≤ 56 R | Piotr K. Skowro transfer matrix element is non 56 R 4 ]. The beam current and RF power measurements were 9 shows that the RF power is almost fully absorbed by the beam. The 3 RF power measured at the accelerating structure input and output with beam. Figure 3: CTF3 performed the beam recombination in two stages. First, the Delay Loop (DL) converted The first RF deflector, operating at 1.5 GHz, sent odd phase-coded sub-pulses to the DL and The combination process must preserve transverse and longitudinal beam emittances: isochro- in the DL, the CRthree-dipole and isochronous the cells transfer with line three connecting independent quadrupole them. families, The whose CR tunability range layout was based on the use of a 1120 ns long bunch trainthe with a charge current contained of ~4 in Apulses satellite into to 4 produce bunches). pulses a of single 140 Later, 140 ns ns the and long ~7.5 Combiner pulse A with Ring (not a counting the maximum (CR) current even interleaved of ones these about straight 30 towards 4 A. DL. the CR. The The bunches sub-pulse leaving length thefrom must DL the correspond were bunches to coming of the the to following length thepulses even of deflector sub-pulse. with the at Their twice orbits half the were of initial mergedRF current the obtaining deflectors and wavelength 140 created distance ns twice a long the time-dependent bunch closed repetition bump at frequency. injection In to the interleave CR thenous a sub-trains. lattices, pair smooth of linear optics,RF low active impedance elements vacuum are chambers all andPETS requires needed diagnostics, a HOM to short bunch free accomplish length. this The bunches task. get elongated if Efficient RF power production in the 2.3 Delay Loop and CR - Bunch Combination zero. Therefore the bunch length preservation requires the use of isochronous optics ( Lessons from CTF3 was assessed in a dedicatedcarefully experiment calibrated [ to compute the beam energyusing gain. a It spectrometer. was Figure then compared with theenergy measurements gain measurements were inRF-to-beam excellent transfer efficiency agreement was with 95.3% including the thethe computed resistive losses. values. stable CTF3 and successfully The proved highly obtained several efficient years with acceleration fully of loaded structures. the drive beam as it was routinely operated over PoS(EPS-HEP2017)537 f N ´ nski / RF λ . After the linac 566 Piotr K. Skowro R for the drive beam current , where N is an integer num- 3 − ]. RF λ 10 11 ) · f ] and these values correspond to a N 75 12 . / 1 at 12 GHz. ◦ ± N ( is the RF wavelength. The fractional part 5 RF λ ]. The operational mode, i.e. the lowest order horizontal dipole one, naturally 10 at 12 GHz for the drive beam bunch phase after combination are allowed. This is ◦ the combination factor (here 4), and f The CLIC two-beam acceleration scheme imposes tight tolerances on the stability of the drive The recombination requires that the ring length is In the RF deflectors of the CR wake-fields in the vertical plane were minimized by detuning Demonstrating the very high beam quality required for CLIC was an integral part of the CTF3 N maximum of 1% to the luminosity- loss per discussed parameter. later This - already capable assumes of a reducing feed-forward the system phase jitter to 2 beam current, energy and phase. A maximum variation of 0 2.4 Beam Stability Issues could not be damped or detuned.fill-time The of turn-by-turn the direct travelling wake-field wave build-upof deflectors was avoided the was because orbit short errors enough by (~1000.6 wake-fields ns). in was The both minimized residual planes. by amplification setting Forthe the the deflectors. fractional same tune reason of the the beam CR optics to was about chosen to minimize the beam size in and damping [ experimental program. In thedrive last beam years performance of optimization. the Thewas machine control particularly operation of improved. special emittance effort growth, Emittance wasgood availability preservation closure put and required of stability into the a the DL good andpersion. control CR The orbits, of isochronous proper optics the matching in optics, from DL,This, the a CR linac combined and very and the with control transfer a of lines spurious were r.m.s.which relatively dis- was strongly the energy focusing. main spread source of ofoptics emittance about growth. was 0.6%, The particularly lead most important constrained to growthoptimized by a was in to building large the space nonlinear reduce DL, dispersion, whose limitations. theof growth, A was Twiss new commissioned. parameters DL and optics, Alsodispersion dispersion tools which was in for was minimized more the with precise helpprocedures. different measurements of beam-lines While Dispersion were the Free beam developed. Steering< combined and 150 only µm The Dispersion by in Target spurious the both Steering planes, CRbeam the was met minimum about the horizontal 250 CLIC emittance µm emittance forbunch ( the requirements combination 100 full of principle, µm factor CTF3 in 8 has recombined vertical).of allowed drive such Besides us a demonstrating to process, the develop validating feasibility an also of the optimized the special setting-up diagnostics CLIC procedure needed [ Lessons from CTF3 fits well the requirements. The DLquadrupoles. loop Sextupoles could was be made used out to of controlthe the 2 bunch second-order six-dipole length matrix was cells term less with than eight 1from independent mm r.m.s. RF In power CLEX a production bunchwas length and of consistent confirmed ~2 with mm by required r.m.s. was direct isochronicityavoiding estimated also conditions streak coherent and camera synchrotron entirely radiation, measurements. sufficient which would for Such affect CTF3 shorter length operation, bunches. ber, was measured precisely by Fourierwas transform adjusted of using a the dedicated beam wiggler phase which monitor could elongate signal. the trajectory The up ring to length 7 cm. and about 2 because they contribute quadratically to the luminosity loss [ PoS(EPS-HEP2017)537 · ´ nski ]. With 16 r.m.s. was 3 − 10 · Piotr K. Skowro and r.m.s. amplitude ◦ 05 ], better than the required . 13 [ 3 − and to keep it at such level on time 10 · ◦ 2 . 54 . 10 min.) was measured within the CLIC 0 ≈ = I / I . It was improved by better stabilizing the gun ∆ 3 . After further improvements, in 2016 the r.m.s. 6 − 3 ]. The stability of the combined beam current in − 10 ]. 14 · 10 2 · 15 ]. = 75 18 . I 0 / I = ∆ (3 GHz). The relative pulse-to-pulse amplitude jitter has been I ◦ / I ]. ∆ 035 . 17 ]. In CTF3 the mean pulse-to-pulse phase jitter measured with respect to ]. In the final CTF3 runs, experiments aiming at demonstrating performances 12 15 , meaning that the observed jitter was the same with and without the beam. Such a performance In CTF3, PETS prototypes were tested with beam in TBL and in TBTS (and later TBM). Another CLIC feasibility verification was the PETS On-Off mechanism. It switches off indi- The pulse-to-pulse current variations in the CTF3 linac were measured using inductive beam To assure the required drive beam timing stability below 50 fs r.m.s., or equivalently a phase During the initial years of operation CTF3 suffered from relatively large beam jitters and drifts. 4 − scales of about 10 minutes [ The structures in thenominal two CLIC lines parameters for had power and different pulseMaximum lengths length RF were power and reached reached a and at exceeded the little for nominalthe both pulse nominal bit of length value different them. of for 240 construction. CLIC, ns 135 was MW about The [ 300 MW, well above 3. Two-beam acceleration 3.1 Power generation, PETS On-Off was achieved for periods of tens of hours [ vidual PETS whenever localized breakdowns threatenalso the needs normal to machine provide operation. aeither The gradual the system ramp-up main of accelerating structure theextension and/or generated to the power PETS PETS in itself. consisting order of The to two prototype reprocess high is afterwards power a variable compact RF external reflectors. It was extensively tested heater power supply and by acurrent feedback, stability to for obtain CLIC of current jitter at the end of the10 drive linac was at the level of the electronic noise floor of the BPMs 2 additional fine-tuning in 2016, the finalthe year achieved of phase operation jitter at to CTF3, below it the was CLIC possible requirement to of further 0 reduce position monitors. Initially it was stability (jitter) below 0.2 degrees ofsystem. 12 GHz, This CLIC system will poses beTherefore, a equipped a significant with prototype challenge a was ’phase in designed, feed-forward’ terms installedphase and of jitter tested of bandwidth, in 0.28±0.02 resolution CTF3. has and been After latency. one demonstrated, year very of close experience to a the CLIC specifications [ an external reference was 0 0.21%. 2.5 The Drive Beam Phase Feed-Forward Dedicated studies identified their sources,feedback which systems [ were either removed or compensated by proper Lessons from CTF3 close to the CLICshort-term requirements RF were stability over added 500 consecutive to RF pulses the ( CTF3 program. For the CTF3 klystrons the CLEX, at the end of the experimental lines, was also largely improved and 3 tolerances, for instance. The CLIC requires r.m.s. phase jitter below 0 jitter below 0.2% [ measured for periods longer then 5 hours [ PoS(EPS-HEP2017)537 ), 3 ´ E = E = nski − Δ Δ shows an 4 Piotr K. Skowro ]. Figure 18 ]. The measurement of all the 19 7 ]. 21 E = 32 MeV were reached with breakdown rates of a few 10 Δ ]. The beam was accelerated in three 3 GHz accelerating structures recuperated 20 At the end of 2014 in place of the TBTS the Two-Beam Module, TBM, a 2 m long fully The Test Beam Line (TBL) served to study the stability of the drive beam during deceleration. The key purpose of CTF3 was to demonstrate the CLIC two-beam acceleration scheme. An 21.4 MeV. Energy gains of up to while higher gradients, up to 165 MV/m were achieved with higher rates [ representative unit of the CLICThe main module linac, was including conditioned anthe to active module alignment the functionality system, nominal were was CLIC carriedactive installed. alignment gradient/pulse out. system length and This measurements and included ofexperimental extensive precision transverse results tests wake-field is and effects. still of reliability undergoing. A studies So fullsimulations. far of analysis all of the the the results are consistent with specifications and 3.3 The Test Beam Line, TBL It consisted of a FODO lattice withalignment 14 was consecutive possible PETS thanks installed to in high thebeam precision drift was spaces. BPM’s and Precise decelerated quadrupole beam from active movers.corresponds it 25 to initial A the energy drive 50% of decelerationaverage 135 each milestone, MeV PETS which produced down was 90 to one MW20 a of of m power minimum the deceleration and line of initial the reached goals 67 total 1.3 of peak MeV. GW. RF This CTF3. power produced On in less then efficient power transfer to high-gradientthe structures and heart acceleration of of this a technology.stalled "probe" delivering electron In single beam bunches CLEX, is or along bunchto the trains 200 MeV. drive at It consisted 1.5 beam, of GHz a a bunchcathode 24 probe repetition source m beam long rate [ electron and accelerator injector energies was linac up from CALIFES in- with the ~5 MeV/c LEP RF Injector photo- ing Linac 5.5 (LIL). µs A via single anCALIFES 3 RF was pulse GHz usually compressor operated klystron powered with delivering bunch the charges 45tance accelerating of of structures MW around 10 and 0.1 RF nC the µm. pulses and photo-injector. a The dur- beam normalized probe 3 r.m.s. beam emit- GHz energy RF was measured phase,timing in which between a was spectrometer probe phase-locked in and to functionThe the drive of nominal laser the beam CLIC pulse probe for accelerating timing. gradient maximum To of acceleration adjust 100 phase the MV/m scans relative corresponded were to an performed. energy gain of RF signals were in remarkable agreementset to with off the the model accelerating predictions structure in receivesimpossible. less all Also than conditions. the 1% power of When inside the it PETS powerthe is is what likelihood makes attenuated of any to a breakdowns ~ breakdown 25% by of a the factor nominal 102-103. value what reduces 3.2 Acceleration, Two-Beam Module example measurement of probe beam31 acceleration MeV using corresponds a to an spectrometer acceleratingthe screen. probe gradient beam The of was 145 value also MV/m. extensively studied The [ effect of breakdown kicks on Lessons from CTF3 with beam in the TBTS and thewith switching different off of beam the and PETS power RF production settings, has been up demonstrated to 16 A and 200 MW [ PoS(EPS-HEP2017)537 ´ nski Piotr K. Skowro ]. In some cases a BDR reduction up to an 23 8 at the design gradient of 100 MV/m. Nevertheless, beam-loading significantly 7 − Probe Beam observed in the TBTS spectrometer screen with the 12 GHz RF power from the drive ]. 22 The RF breakdown rate (BDR) is critical for the luminosity performance of the CLIC lin- The dynamics of drive beam undergoing deceleration in the transverse planes was studied in changes the field profile in theexperiment structures, using and the potential CTF3 effects need drivetions to beam be were was understood. setup collected A and in dedicated data between for 2014 different and beam-loading 2016 configura- [ 4. Other experimental tests in CTF3 4.1 The Beam-Loading Experiment ear collider. High powerstrated RF rates of testing 10 of a number of 12 GHz CLIC prototype structures demon- detail. At the beginningof and the end beam of energy the loss linequadrupolar and a scans. its time-resolved energy Both spectrometer spread. longitudinal provided andtions Transverse measurement [ Twiss transverse parameters parameters were agree measured very with well with the simula- Figure 4: beam on (top) and off (bottom). The energy gain is about 31 MeV, corresponding to a gradient of 145 MV/m. order of magnitude was measured. Theby results the support the peak hypothesis gradient of and theinduced BDR its by being reduction dominated the being beam. associated to Also,lows the roughly the the modification measured gradient of distribution profile, the of which gradient additionally the confirms profile breakdowns this inside hypothesis. the Therefore, structure a fol- further Lessons from CTF3 PoS(EPS-HEP2017)537 ´ nski ]. ]. 25 30 , 24 Piotr K. Skowro ]. Also, the cavity BPMs of ]. Also, the amplitude of the 26 29 , 28 ]. 27 9 ] program, using the CALIFES linac, will give the opportunity to maintain some 31 The CLIC Test Facility CTF3 conducted a rich experimental program, addressing various as- Prototypes of drive beam BPM were also tested yielding 2 µm resolution. However, the per- At CLEX, along TBL and TBM lines, a cost effective optical fibre Beam Loss Monitor (BLM) As a part of development of non-destructive profile monitors based on diffraction radiation, An extensive test program for the main CLIC beam instrumentation components was estab- Wake Field Monitors (WFM) detects particular HOMs excited by the beam in the CLIC ac- pects of the accelerator technologyissues needed related for to drive the beam CLIC generation, power concepthigh-gradient production and and acceleration two-beam solving beyond acceleration. the 100 In vast particular, MV/m majoritylished, using of as X-band well room as temperature the issource now production of well and X-band estab- use RF of power aexperimental in high-current program the drive in range beam December of as 2016new hundreds an as CLEAR of efficient planned, [ and MWs. and reliable stopped CTF3 operation.local successfully testing The completed capability approval its at of CERN the forbeam, CLIC alongside instrumentation with and other high-gradient non-CLIC-related structure testing accelerator with R&D. 5. Conclusions formance of the initial versiondrive beam. was largely An degraded improved design in was presence successfully of tested 12 in GHz 2015 RF [ power from the system was installed. Thewere performed. system The was provoked successfully losses along commissionedthe the expected and accelerator accuracy lines various below were verification 2 localised tests by m, the within BLMs CLIC with requirements [ optical transition radiation interferenceeffects was were measured studied. in imaging In conditions, confirming particular, the for theoretical predictions the [ first time shadowing signals agreed very well with conventional ionization chambers. lished in CTF3 inThese order devices to need to verify provide the state-of-the-artis performance, performance such or that of above. cost-effective solutions the In are many prototypesthe mandatory. cases direct Additionally, in their they vicinity number a need of to hundreds realistic detect MW environment. tiny RF signals power in and operate in highlycelerating radioactive structures. environment. HOM signals arestructure picked cells. up Two different by frequency 4 bands are waveguideto analysed antennas the to attached structure measure to with the one beam a offset of requiredCTF3, with resolution the and respect of both 3.5 demonstrated µm. performances Two better slightly or different close versions to were the tested required in ones [ Lessons from CTF3 optimization of the CLIC structurebreakdowns along is the possible structure during by the profiling operation the with beam gradient is such constant. that4.2 distribution Beam of Diagnostics Tests the main linac initially showedwas worse below than specifications. required Stainless time steelcavity resolution was and replaced when the with the copper Q position as valueencouraging resolution the but was building still optimized. quite material far of The from the requirements improved [ version showed a resolution below 1 µm, PoS(EPS-HEP2017)537 ´ nski Piotr K. Skowro 10 2002-008 (RF). Design Report", CERN, Geneva, Switzerland, CERN-2012-007;PSI-12-01; SLAC-R-985; JAI-2012-001. KEK-Report-2012-1; Conf., Monterey, CA, USA, August 2000, pp. 95-97. CERN", in Proc. EPAC 2006, Edinburgh, UK, June 2006, pp. 798-800. International Particle Accelerator Conf., Kyoto, Japan, May 2010, pp. 1107-1109. CTF3 Injector", in Proc. EPAC 2006, Edinburgh, UK, June 2006, pp. 771-773. Gyeongju, Korea, August 2002, pp. 34-36. Particle Accelerator Conf., Lucerne, Switzerland, July 2004, pp. 39-41. Accelerator Conf., Knoxville, Tennessee, USA, August 2006, pp. 31-33. facility and mitigation by damped deflecting022001 structures", (2011). Phys. Rev. ST Accel. Beams, vol. 14, p. Linear Accelerator Conf., Tsukuba, Japan, September 2010, pp. 103-105. Linear Colliders, Geneva, Switzerland (2010), http://agenda.linearcollider.org/event/4507/contributions/17550/attachments/14172/23264/CTF3BeamCurrentStability.pdf Test Facility CTF3", in Proc. IPAC 2016,3350. Busan, Korea, May 2016, paper THPMB046, pp. 3347 - Busan, Korea, May 2016, paper WEPOR007, pp. 2677 - 2680. This paper documents, surely in a largely incomplete manner, over more than a decade long [1] G. Geschonke and A. Ghigo Eds, "CTF3 Design Report", CERN, Geneva,[2] Switzerland, CERN/PS M. Aicheler et al., "A Multi-TeV Linear Collider Based on CLIC Technology - CLIC Conceptual [3] Y. Thiery, J. Gao, J. LeDuff, "CTF3 Drive-Beam Injector Design", in Proc.[4] 20th InternationalP. Linac Urschutz et al., "Beam Dynamics Studies and Emittance Optimization in the[5] CTF3 LinacA. at Dabrowski et al. "Measuring the Bunch Frequency Multiplication at CTF3"[6] in Proc. 1st P. Urschutz et al., "Beam Dynamics and First Operation of the Sub-Harmonic[7] Bunching SystemE. in Jensen, the "CTF3 Drive Beam Accelerating Structures", in Proc. 21st International[8] Linac Conf., R. Corsini et al. "First Full Beam Loading Operation with the[9] CTF3 Linac"P. in Urschu?tz Proc. et 9th al. European "Efficient Long-Pulse Fully Loaded CTF3 Linac Operation" in Proc. 2006 Linear collective effort of a largeparticipated over collaboration. this period The to the authorsof conception, the wish design, CLIC construction, to Test commissioning Facility, acknowledge CTF3. and all operation individuals who References [10] D. Alesini et al., "Beam instability induced by RF deflectors in the combiner ring of the[11] CLIC test R. Corsini et al., "CTF3 Status[12] and Plans",D. ICFA Schulte Beam et Dynamics al., Newsletter, vol. "Status 62, Of p. The 165 CLIC (2013). Phase and Amplitude[13] Stabilisation Concept",G. in Sterbini, Proc. "Beam 25th current stability in CTF3", presented at the International Workshop on Future [14] P.K. Skowronski et al., "Status and Plans for Completion of the Experimental Programme of the CLIC [15] L. Malina et al., "Recent Improvements in Drive Beam Stability in CTF3", in Proc. IPAC 2016, Lessons from CTF3 6. ACKNOWLEDGEMENTS PoS(EPS-HEP2017)537 ´ nski Piotr K. Skowro 11 Latency Drive Beam Phase Feedforward System2016, at Busan, the Korea, CLIC May Test 2016, Facility paper CTF3", WEPOR006, in pp. Proc. 2673 IPAC - 2676. 2002-008 (RF). Sebastian, Spain, September 2011, pp. 1042-1044. Mechanism", in Proc. IPAC 2012, New Orleans, Louisiana, USA, pp. 1852-1854. Conf., Victoria, British Columbia, Canada, September-October 2008, pp. 389 - 391. accelerator structure", Phys. Rev. ST Accel. Beams, vol. 16, 081004 (2013). thesis, Norwegian University of Science andCERN-THESIS-2010-246. Technology, Trondheim, Norway, 2010, CTF3", presented at IPAC’17, Copenhagen, Denmark, May 2017, paper TUPAB017, this conference. Tests", in Proc. of LINAC 2014,pp. Geneva, Switzerland, 121 August - - 123. September 2014, paper MOPP030, 2016, Busan, Korea, May 2016, paper WEOBB02, pp. 3347 - 3350. Beam Line of the CLIC Two-Beampaper Module MOPMR019, at pp. CTF3", 3347 in - Proc. 3350. IPAC 2016, Busan, Korea, May 2016, Linac", in Proc. IBIC15, Melbourne, Australia, September 2015, paper TUPB060, pp. 475 -Melbourne, 478. Australia, September 2015, paper MOPB045, pp. 148 - 151. electron pulses", in Proc. IBIC15, Melbourne,584. Australia, September 2015, paper WEBLA03, pp. 580 - IBIC15, Melbourne, Australia, September 2015, paper TUPB057, pp. 461 - 464. Lessons from CTF3 [16] J. Roberts et al., "Demonstration of CLIC Level Phase Stability using a High Bandwidth, Low [17] J. Roberts? and A. Ghigo Eds, "CTF3 Design Report", CERN, Geneva,[18] Switzerland, CERN/PS P.K. Skowronski et al., "The CLIC Feasibility Demonstration in CTF3", in Proc.[19] IPAC 2011, San I. Syratchev et al., "High Power Operation with Beam of a[20] CLIC PETS EquippedF. Peauger with et On/Off al., "Status of the CTF3 Probe Beam Linac CALIFES",[21] in Proc.A. 24th Palaia Linear et Accelerator al., "Effects of RF breakdown on the beam in[22] the CompactR. Linear Lillestol, Collider "Power prototype production experiments at the Test Beam Line in the CLIC Test Facility 3", Ph.D. [23] E. Senes et al., "Results of the Beam-Loading Breakdown Rate Experiment[24] at the CLICJ.L. Test Navarro Facility Quirante et al., "CALIFES: A Multi-Purpose Electron Beam for Accelerator Technology [25] R. Lillestol et al., "Status of wakefield monitor experiments at the[26] CLIC Test Facility",A. in Benot-Morell Proc. et IPAC al., "Beam Tests of the Prototype Beam Position Monitoring System for the Drive [27] J.R. Towler et al., "Development and Test of High Resolution Cavity BPMs[28] for theM. CLIC Kastriotou, Main et Beam al., "BLM crosstalk studies on the CLIC Two-Beam Module",[29] in Proc.E. IBIC15, Nebot Del Busto, et al., "Position resolution of optical fibre-based beam loss monitors using long [30] R. Kieffer et al., "Development of a Versatile OTR-ODR Station for Future[31] Linear Colliders",http://clear.web.cern.ch in Proc.