Towards a Multi TeV Linear Collider; Drive Beam Generation with CTF3

Transcription

1 Towards a Multi TeV Linear Collider; rive Beam Generation with CT3 H.H. Braun / CERN, on behalf of the CT3 collaboration Introduction CLIC & CT3 CT3 status and achievements CT3 outlook

2 CLIC aim: develop technology for e - /e + collider with E CMS = 3 TeV covering full LHC physics reach with complementary lepton collision experiments Physics motivation: "Physics at the CLIC Multi-TeV Linear Collider : report of the CLIC Physics Working Group," CERN report Present goal: emonstrate all key feasibility issues by 2010

3 BASIC EATURES O CLIC High acceleration gradient (150 MV/m) Compact collider - 3 TeV with overall length < 50 km Normal conducting accelerating structures High acceleration frequency Two-Beam Acceleration Scheme Cost-effective & efficient Simple tunnel, no active elements Central injector complex Modular design, can be built in stages

4 CLIC TWO-BEAM SCHEME QUA rive beam QUA - High current - Low decelerating field POWER EXTRACTION AN TRANSER STRUCTURE (=PETS) ACCELERATING STRUCTURES R - CLIC TUNNEL CROSS-SECTION Main beam Low current - High accelerating field BPM 4.5 m diameter

5 CLIC 3 TeV old parameters delay 21 m CR1 84 m combiner rings CR2 334 m 352 klystrons 40 MW, 94 μs drive beam accelerator 2.37 GeV,, 937 MHz decelerator, 21 sectors of 669 m BS 2.6 km BS 2.6 km BC2 e - main linac, 30 GHz, 150 MV/m, 14 km IP1 e + main linac BC km train combination Δ B 16 cm 8cm booster linac, 9 GeV,, 3.75 GHz e - injector 2.4 GeV e - R 360m BC1 e + R 360m e + injector, 2.4 GeV

6 Next slides resembles almost the previous, but we have changed 6 details. Who finds them first?

7 CLIC 3 TeV new parameters delay loop CR1 238 klystrons 33 MW, 140 μs drive beam accelerator 2.4 GeV,, 1.3 GHz? combiner rings CR2 decelerator, 17 sectors of 1235 m BS 2.6 km BS 2.6 km BC2 e - main linac, 12 GHz, 100 MV/m, 21 km IP1 e + main linac BC km booster linac, 9 GeV,, 2.4 GHz e - injector 2.4 GeV e - R 360m BC1 e + R 360m e + injector, 2.4 GeV

8 Recent changes of key CLIC parameters Main Linac R frequency Accelerating field Overall E CMS = 3 TeV 30 GHz 12 GHz 150 MV/m 100 MV/m 33.6 km 47.6 km Why? Very promising results of earlier Molybdenum test structures not reproduced for test conditions closer to LC requirements (i.e. long R pulses, low breakdown rate, structures with HOM damping) Copper structure tests don t t indicate advantage of frequencies>12 GHz for achievable gradient Parametric cost model indicates substantial cost savings for 12 GHz/100 MV/m (flat minimum for this parameter range) Increase chance of feasibility demonstration by MV/m is lowest gradient for a 3 TeV machine See Walter Wuensch s talk Thursday

9 CLIC R power source layout rive Beam Accelerator efficient acceleration in fully loaded linac elay Loop x 3 gap creation, pulse compression & frequency multiplication R Transverse eflectors Combiner Ring x 3 Combiner Ring x 3 pulse compression & frequency multiplication pulse compression & frequency multiplication rive Beam ecelerator Section (2 x 17 in total) Power Extraction rive beam time structure - initial rive beam time structure - final 126 ns 126 ns 4.5 μs 100 μs train length - 32 x 21 x 2 sub-pulses A 2.5 GeV - 64 cm between bunches 2 x 17 pulses 180 A - 2 cm between bunches

10 Motivation and Goals of CT3 collaboration Build a small-scale scale version of the CLIC R power source, in order to demonstrate: full beam loading accelerator operation electron beam pulse compression and frequency multiplication using R deflectors Provide the R power to test the CLIC accelerating structures and components Tool to demonstrate until 2010 CLIC feasibility issues identified by ILC-TRC in 2003

11 CT3 layout I b ν b =1.5 GHz 1400 ns t 3.5 A rive Beam Injector rive Beam Accelerator, 150 MeV 30 GHz High Gradient Test stand 10 x I B, 10 x ν B X 2 elay loop 42 m I b X 5 ν b =3 GHz 140 ns t 7A Combiner Ring 84 m CLEX rive beam stability bench marking eceleratortest Beam Line I b ν b =15 GHz 35 A Two-Beam Test stand & Linac subunit CLIC sub-unit 200 MeV Probe Beam Injector 140 ns t

12 CT3 collaboration official members Country 20 member states inland rance India Italy Pakistan Russia Spain Sweden Switzerland Turkey USA Institute CERN Helsinki Inst. of Physics APNIA LAL LAPP BARC RRCAT LN NCP BINP IAP JINR CIEMAT IIC UPC Uppsala University PSI Ankara Universities NWU SLAC collaboration board chairman M. Calvetti / LN spokesperson G. Geschonke / CERN

13 commissioned with beam CT3 build by a collaboration like a particle physics experiment Thermionic Injector SLAC/USA IN2P3/rance Linac NWU/USA CERN L LN/Italy CR 2006 LN/Italy BINP/Russia CIEMAT/Spain IN2P3/rance Photo injector / laser 2008 CCLRC/UK IN2P3/rance 30 GHz production (PETS line) and test stand IAP/Russia Ankara Univ./Turkey ubna TL2 RRCAT/India CLEX (building in 2006) CEA&IN2P3/rance TSL/Sweden CIEMAT+Uni. Valencia+Uni. Barcelona/Spain NCP/Pakistan

14 CT3 in 2006 elay Loop Linac Beam up to here 30 GHz R power testing Transfer Line TL2 and Combiner Ring

15 ully beam loading operation in CT3 High beam current R in No R to load Most of R power to the beam short structure - low Ohmic losses CT3 rive Beam Acc. Structures (3 GHz) SICA (Slotted Iris Constant Aperture): 32 cells 1.2 m long 2π/3 mode 6.5 MV/m av. acc. gradient for 3.5 A beam current HOM damping slots theoretical R-to-beam efficiency: 96% HOM damping slot SiC load

16 CLIC: no R pulse compression length of the drive beam pulse: 100 µs emonstration at CT3: ull beam loading operation in CT3 emonstration for CLIC operation MKS03 MKS05 MKS06 MKS07 Spectrometer 4 Spectrometer 10 Setup: no R pulse compression for this experiment (with exception of MKS03) 1.5 µs long pulses Adjust R power and phase and beam current, that fully loaded condition is fulfilled R pulse at structure input R pulse at structure output analog signal 1.5 µs beam pulse

17 ull beam loading operation in CT3 emonstration for CLIC operation Idea: elay always one klystron pulse after the beam pulse and measure relative energy in spectrometer 10 and compare with calculations. An exact knowledge of the structure input power, the beam current and the energy gain is essential. MKS05 MKS06 MKS07 compare to theoretical energy gain (input power, beam current) in out in in in in total energy lower energy o missing acceleration (energy gain per structure) o deceleration due to direct beam loading from calculations (beam current) measured R-to-beam efficiency: 95.3 % Theory: 96% (~4 % ohmic losses)

18 How does the bunch frequency multiplication work? CT3 Injector with 3 SHB cavities (1.5 GHz) SHB SHB gun SHB buncher 2 accelerating structures Phase coding and bunch frequency multiplication in delay loop Beam combination with transverse R deflector phase coding

19 Commissioning of the elay Loop SHB system Key parameters for the SHB system: 1) time for phase switch < 10 ns ( GHz periods) 2) satellite bunch population < 7 % (particles captured in 3 GHz R buckets) phase switch: satellite bunch population: main bunch satellite bunch Phase switch is done within eight 1.5 GHz periods (<6 ns). Satellite bunch population was estimated to ~8 %.

20 0 2 2 Beam recombination in the elay Loop (factor 2) I [A] More details abio Marcellini s talk (Thursday) t [ns] 2 3 1

21 Summary of recent CT3 Achievements Nominal beam production and stable acceleration of 3.5 A beam with full pulse length without significant emittance growth. Wakefields kept under control with HOM damping+detuning and strong transverse focusing. Measured performance is consistent with predictions from beam dynamics simulations. Measured R power to beam energy transfer efficiency of 95% in fully loaded operation for normal conducting linac! Proves that drive beam production is as efficient as predicted. emonstration of bunch frequency multiplication with delay loop using R deflector cavities and phase coding with rapidly phase switched subharmonic buncher.. This is a key ingredient to achieve bunch train compression. Routine 24h, 7 days a week operation of fully loaded linac for 30 GHz production fully loaded operation can be very reliable and stable.

22 Next step: Combiner Ring commissioning spring 2007 CERN: Layout, infrastructure, cabling, magnets, power supplies, installation CIEMAT: Septa magnets, sextupoles, correctors, extraction Kickers INN: R deflectors, wiggler, vacuum chambers, BPM (BPI) LAPP: BPM electronics LURE: quadrupoles BINP: magnet realization

23 Some remarks about CLIC parameter change and CT3 Bunch repetition frequency of drive beam can be readily chosen asa 6, 9, 12, 15 GHz by varying number of stacking turns in combiner r ring and fine tuning of ring circumference with wiggler. rive beam can produce R on any harmonic of these frequencies. This makes adaptation of CT3 drive beam to new frequency straight forward! efinitive frequency choice was urgent, since ordering of R components for CLEX two beam test has to start now.

24 unctionality and Specifications for TL2 (commissioning spring 2008) Transport of drive beam from combiner ring extraction to CLEX Bunch length manipulation with R 56 variable in the range -0.35m< 0.35m<R 56 <0.35m, with compensated T 566. Emittance dilution < 10% (for 150 MeV, ε x,y =100 μm) Vertical achromat for 50 cm vertical displacement to adapt for different floor level of CLEX relative to EPA building Tailclipper consisting of a fast kicker plus a collimator dump to adjust beam pulse length for drive beam in two beam test stand and TBL rive Beam Injector rive Beam Accelerator 16 structures -3 GHz -7 MV/m 3.5 A μs 150 MeV X 2 elay Loop X 5 Combiner Ring UMP UMP Two-beam UMP Test ITBArea UMP UMP TBL 30 GHz Teststand LIL -ACS 150 MV/m 30 GHz UMP 1m wide passage all around UMP LIL -ACS Probe beam injector 30 GHz and Photo injector test area TL2 35 A ns 150 MeV or more details talk by Amalendu Sharma (Tuesday)

25 1 CLEX building existing building Test Beam Line TBL 8 m UMP 2.0m UMP 6 m UMP 16.5 m TBTS 16 m ITB m Transport path 1.4m UMP TBL 22.4 m 1.85m LIL-ACS TL2 2 m LIL-ACS LIL-ACS 22 m CALIES Probe beam injector UMP 3.0m 3.0m June m Construction on schedule Equipment installation from May 2007, Beam foreseen from March 2008 Jan 2007

26 CLEX Glossary CLEX=CLIC EXperimental area TBTS=Two Beam Test Stand Testbed for 12 GHz R tests of drive beam decelerating structures (PETS) and main beam accelerating structures. emonstration of two beam acceleration TBL=Test Beam Line easibility demonstration of CLIC drive beam decelerator CALIES=Concept Concept d Accd Accélérateur Linéaire pour aisceau d Electronsd Sonde 3 GHz probe beam injector to simulate main beam in TBTS TL2 switchyard for drive beam and drive beam diagnostics ITB=Instrumentation Test Beam Option for 2 nd beamline connected to CALIES for development and test of beam diagnostic equipment

27 Layout of CLEX-A (A=Accelerator housing) floor space 8 m 1.4 m UMP UMP 1 UMP 6 m ITB m 16 m TBTS 2.5m walk around zone 1.4m UMP TBL 22.4 m 1.85m LIL-ACS 23.2 m LIL-ACS LIL-ACS UMP 3.0m 3.0m TL2 CALIES probe beam injector 1.4m Space reservations CALIES TBTS TBL ITB 42.5 m 23.2 m from cathode manipulator arm to exit flange of spectrometer er 16.6 m from output spectrometer to end of beam dump 31.4 m from dogleg bend to end of beam dump ITB 16.0 m from 2 nd dogleg magnet to end of beam dump (optional, not funded yet)

28 180 MeV Probe Beam Injector CALIES=Concept d Accélérateur LInéairepour aisceau d ElectronsSonde choice of architecture : 1 photo-injector 3 LIL sections: 1 for compression and 2 for acceleration 1 beam line with diagnostics (leading to 2-beam teststand) Laser R pulse compression 2 x 45 MW K steerer position monitor profile monitor beam dump quadrupoles 15 MV/m compression 17 MV/m acceleration 17 MV/m acceleration rf gun cavity focusing coils LIL sections R deflector spect. magnet

29 Probe Beam R Gun PHIN

30 Laser system schematic PHIN 400 μs, 5-50 Hz 200 μs, 5-50 Hz 1.5 GHz Nd:YL oscillator Phase coding CW preamp 3-pass Nd:YL amplifier x300 3 kw 2 μj 3 pass Nd:YL 200 μs, 5-50 Hz amplifier x5 ~2332 e - bunches 2.33 nc/bunch ~2332 pulses 370 nj/pulse 1.55 μs iode pump 18 kw pk eedback stabilisation iode pump 22 kw pk 15 kw 10 μj 270 μs 4ω 2ω Optical gate (Pockels cell) Energy stabiliser (Pockels cell) Beam conditioner

31 CERN installation Amplifier 2 Amplifier 1 Preamplifier Pulse slicing Pockels cell Oscillator iber-optics coding system

32 waveguide

33 Conclusions New CLIC key parameters to adapt to recent structure test results s and outcomes of cost optimizations CT3 installations and machine experiments on schedule for feasibility proof by 2010 Organization of CT3 as an international collaboration modeled aftera big particle physics experiment works astonishingly well!