Recent Progress at the CLIC Test Facility 3 at CERN

Transcription

1 Recent Progress at the CLIC Test acility 3 at CERN P. Urschütz

2 Talk outline Introduction to the CLIC two-beam scheme The CLIC Test acility CT3 Results from CT3 Past Recent Results Outlook on future activities Conclusions

3 CLIC aim: evelop technology for e - /e + collider with E CM = 1-5 TeV Present mandate: Motivation: emonstrate all key feasibility issues by 2010 (CT3) Aim to provide the High Energy Physics community with the feasibility of CLIC technology in due time, when physics needs will be fully determined following LHC results (2010?).

4 WORL WIE CLIC COLLABORATION Ankara University (Turkey) Berlin Tech. Univ. (Germany) BINP (Russia) CERN CIEMAT (Spain) APNIA/Saclay (rance) epartment of Atomic Energy (India) innish Industry (inland) Helsinki Institute of Physics (inland) IAP (Russia) Instituto de isica Corpuscular (Spain) INN / LN (Italy) JASRI (Japan) JINR (Russia) KEK (Japan) LAL/Orsay (rance) LAPP/ESIA (rance) LLBL/LBL (USA) North-West. Univ. Illinois (USA) Polytech. University of Catalonia (Spain) RAL (England) SLAC (USA) Svedberg Laboratory (Sweden) Uppsala University (Sweden)

5 CLIC main parameters at 3 TeV Center of mass energy E cm 3000 GeV Main Linac R requency f R 30 GHz Luminosity L cm -2 s -1 Luminosity (in 1% of energy) L 99% cm -2 s -1 Linac repetition rate f rep 150 Hz No. of particles / bunch N b No. of bunches / pulse k b 220 Bunch separation Δt b (8 periods) ns Bunch train length τ train 58.4 ns Beam power / beam P b 20.4 MW Unloaded / loaded gradient G unl/l 172 / 150 MV/m Overall two linac length l linac 28 km Total beam delivery length l B 2 x 2.6 km Proposed site length l tot 33.2 km Total site AC power P tot 418 MW Wall plug (R) to main beam power efficiency η tot 10 %

6 Basic features of CLIC High acceleration gradient (150 MV/m) Compact collider - overall length < 40 km Normal conducting accelerating structures High acceleration frequency (30 GHz) Two-Beam Acceleration Scheme Capable to reach high frequency Simple tunnel, no active elements OVERALL LAYOUT O CLIC OR A CENTER-O-MASS ENERGY O 3 TeV Central injector complex Modular design, can be built in stages

7 QUA rive beam A, 70 ns from 2.5 GeV to 250 MeV QUA POWER EXTRACTION STRUCTURE ACCELERATING STRUCTURES Main beam 0.6 A, 60 ns from 9 GeV to 1.5 TeV BPM 30 GHz 150 MW CLIC TUNNEL CROSS-SECTION CLIC MOULE (12000 modules at 3 TeV) CLIC two-beam scheme 3.8 m diameter

8 CT II - ismantled in 2002, after having achieved its goals CT II 30 GHz MOULES rive beam line Main beam line

9 Peak Accelerating field (MV/m) High-gradient tests in CT II cell clamped tungsten-iris structure CLIC goal unloaded 154 MV/m continued after inspection still no damage 4.0 mm copper structure - damaged 3.5 mm copper structure - damaged 3.5 mm (177 tungsten MV/m iris at 8 - ns) undamaged 3.5 mm molybdenum iris- undamaged CLIC goal loaded No. of shots 10 6 A 30-cell structure with Mo irises and low E S /E A largely exceeded the CLIC accelerating field requirements without any damage 190 MV/m accelerating gradient in first cell - tested with beam! (but only 16 ns pulse length)

10 The CLIC R power source rive Beam Generation Complex Main Beam Generation Complex

11 What does the R Power Source do? The CLIC R power source can be described as a black box, combining very long R pulses, and transforming them in many short pulses, with higher power and with higher frequency 350 Klystrons Power stored in electron beam Power extracted from beam in resonant structures Accelerating Structures low frequency high efficiency high frequency high gradient Long R Pulses P 0,n 0, τ 0 Electron beam manipulation Short R Pulses P A = P 0 N 1 τ A = t 0 / N 2 ν A = ν 0 N 3

12 rive Beam Accelerator efficient acceleration in fully loaded linac elay Loop 2 gap creation, pulse compression & frequency multiplication R Transverse eflectors Combiner Ring 4 Combiner Ring 4 pulse compression & frequency multiplication pulse compression & frequency multiplication R Power Source Layout rive Beam ecelerator Section (2 21 in total) Power Extraction rive beam time structure - initial 70 ns 70 ns rive beam time structure - final 4.5 μs 100 μs train length sub-pulses A 2.5 GeV - 64 cm between bunches 2 21 pulses 180 A - 2 cm between bunches

13 CT3 motivations and goals Build a small-scale version of the CLIC R power source, in order to demonstrate: full beam loading accelerator operation (power is zero at downstream end of the structure). electron beam pulse compression & frequency multiplication using R deflectors Provide the 30 GHz R power to test the CLIC accelerating structures and components at and beyond the nominal gradient and pulse length (150 MV/m for 70 ns). 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 Two-beam Test Area 150 MV/m Main Beam Injector 35 A ns 150 MeV R ELECTORS HIGH POWER 30 GHz TEST STANS

14 P. Urschütz ESY 31 Oct 2006 CT3 Status Tunable R56 Chicane (INN/LN) Commissioned with beam Commissioned with beam Commissioning starting end 2006 INJECTOR Main beam parameters irst module Cleaning Chicane Nominal Achieved I 3.5 A 5A τp 1.5 μs 1.5 μs E 150 MeV 100 MeV ε n,rms 100 π mm mrad 100 π mm mrad τb,rms 5 ps 4 ps

15 ully beam loading operation in CT3 High beam current R in No R to load short structure - low Ohmic losses Most of R power to the beam 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 HOM damping slot SiC load

16 ull beam loading operation in CT3 Compressed R Pulse: Beam current Beam pulse lenght Power input/structure Ohmic losses (beam on) R power to load (beam on) 4 A 1.5 μs 35 MW 1.6 MW 0.4 MW R signals / output coupler of structure beam off 30 MW R-to-beam efficiency ~ 94%* * No beam energy measurements have been performed 1.5 μs R power 0.4 MW beam on

17 ull beam loading operation in CT3 emonstration for CLIC operation No R Pulse compression one klystron pulse at a time was delayed after the beam pulse measured the difference in energy ( missing acceleration, deceleration due to direct beam loading) Power at structure input irect beam loading signal elayed R pulse, structure input and output power 1.5 µs beam pulse P out = 0, fully beam loaded measured R-to-beam efficiency: 95.3 % (~4 % ohmic losses)

18 Emittance Optimization of the CT3 Injector CT3 Injector in 2005, new coils (decrease of emittance by a factor 2 (Parmela Simulations)) 20 off crest 2 different modes of operation: 30 GHz power 5 A Bunch frequency multiplication (L, Combiner Ring commissioning): 3.5 A beam current 3 sub harmonic buncher (1.5 GHz) on crest acceleration in all structures 3.5 A 30 GHz Power production mode: 5 A beam current sub harmonic buncher off off crest acceleration before magnetic chicane Nominal emittance (normalised, rms): 100 π mm mrad (for 3.5 A on crest operation) Simulation: π mm mrad (3.5 A/ 5 A, on/off crest, after magnetic chicane) Bunch length: 5 ps, < 2 ps in power mode

19 Emittance measurements in the CT3 Linac 3 positions to measure emittance (by means of a quadrupole scan and OTR screen) Measurement results: Mode of operation Bunch frequency Emittance n,rms (Position 1) Emittance n,rms (Position 2) going straight 3 GHz 35 π mm mrad 50 π mm mrad Emittance n,rms (Position 3) going straight 1.5 GHz 60 π mm mrad 80 π mm mrad 30 GHz power 3 GHz 50 π mm mrad 80 π mm mrad At girder 5 we are not to far from simulations Measurement results always below the nominal emittance (100 π) Power production: good transmission through the PETS (90%) Increase of emittance towards the end of the Linac related to the measurement (resolution, different quadrupole scan range) or beam property? to be investigated

20 Commissioning of the elay Loop elay Loop: installed in 2005, commissioned in 2005/2006 L CR transverse deflector e -

21 How does the frequency multiplication work? CT3 Injector with SHB system SHB 0134 SHB 0204 SHB 0214 Phase coding and bunch frequency multiplication in delay loop Beam combination with transverse R deflector phase coding

22 Commissioning of the elay Loop - SHBs Key parameters for the sub-harmonic bunching system: 1) phase switch time < 10 ns 2) satellite bunch population < 7 % phase switch: satellite bunches: main bunch satellite bunch Phase switch is done within eight 1.5 GHz periods (<6 ns). Satellite bunch population was estimated to ~8 %.

23 elay Loop, path length tuning L wiggler has path length tuning range of ~ 9 mm R phase monitor after the L to measure phase error in the R bunch combination GHz Wiggler off Wiggler on R Signal Amplitude (mv) GHz GHz measure harmonics of 1.5 GHz. Better R combination 7.5 & 10.5GHz GHz Time (ns) 9 & 12 GHz

24 I [A] t [ns] 1 Beam recombination in the elay Loop (factor 2)

25 P. Urschütz ESY 31 Oct 2006 High-power transfer line High-gradient test stand CT3 linac Power extraction & transfer structure (PETS) Produced power up to about 100 MW - structure tests started in structures tested until now 30 GHz power production in CT3

26 P. Urschütz ESY 31 Oct 2006 Acceleration structures Structures tested so far (or under test) in CT3: Structure Assembly Circular Cu Brazed cells Circular Mo Clamped cells HS 60 - Cu Clamped quad HS 60 Cu (rev) Clamped quad HS 11 - Mo Clamped quad 11 ~300 HS 11 - Ti Clamped quad 11 just started Phase advance/cell in degree Cell length [mm] Iris radius (first, last) [mm] Iris thickness (first, last) [mm] Q-factor (first, last) Ncell Active structure length [mm] Pin [MW] N. of cells test. time [h] , , , Copper prototype of the new HS geometry

27 CT3 High-Power test results Break own Rate Experiments Cu Mo Results & open questions: HS geometry tested (Cu) no major problem small decrease of performance (under investigation) Mo HS tests just finished slope as steep as for copper! Breakdown rate slope for Mo less steep than Cu material or clamping dependent? Titanium HS under test right now (first results look promising)

28 uture CT3 Activities elay Loop - commissioned with beam Linac - commissioned with beam TL1 CR CLEX TL2 Combiner Ring - commissioning starting end 2006 Commissioning Steps: Transfer Line 1 and CR Injection at the end of 2006 Combiner Ring and Transfer Line 2 in 2007 CLEX (CT3 Experimental Area) from 2008 on

29 uture CT3 Activities - CLEX 40 m 6 m UMP UMP UMP UMP UMP Instrumentation Test beam TBL 30 GHz Test stand UMP 1m wide passage all around LIL-ACS LIL-ACS Probe beam injector UMP 2 m 8 m 3 activities: 30 GHz Test Stand: 1) emonstration of the operation of a full CLIC module. 35 A drive beam with 140 ns pulse length, PETS to produce up to 300 MW power, acceleration of the probe beam. 2) Measure effects of R breakdown on the drive beam, crucial for acceptable breakdown rate. Test Beam Line: Validation of the rive beam stability. Instrumentation Test beam: Use of the probe beam for various instrumentation tests.

30 uture CT3 Activities - CLEX Test Beam Line: Instrumentation section UMP BPM PETS BPM ecelerator OO modules PETS 35 A, 150MeV beam from combiner ring UMP 20 m Main concerns for CLIC drive beam decelerators Beam of very high current (180 A) and damage potential Total energy spread of up to 90%. Beam is decelerated to 10% of its initial energy Wakefield effects TBL as a scaled model of a CLIC drive beam decelerator allows to test the operation and instrumentation for such a decelerator and to benchmark the simulation tools.

31 CONCLUSIONS CLIC is the only possible scheme to extend the Linear Collider energy into the Multi-TeV range CLIC technology is not mature yet, requires a lot of challenging R& Very promising results were already obtained in CT II and in the first stages of CT3 e.g. recently the elay Loop commissioning Aim to provide the High Energy Physics community with the feasibility of CLIC technology in due time, when physics needs will be fully determined following LHC results (2010?). Safety net to the SC technology in case sub-tev energy range is not considered attractive enough for physics.

32 P. Urschütz ESY 31 Oct 2006 Acceleration structure fabrication E-field (breakdown) Pulsed currents (fatigue) Öuse of Mo, or alternative refractory metal. Ö use of CuZr, or improved mechanical strength high conductivity alloy. ÖUse bi-metallic CuZr C15000: pulsed currents Mo: high E-field

33 P. Urschütz ESY 31 Oct 2006 Power Extraction & Transfer Structure ast (15 ms) linear movers etuning wedges ON In interaction with the drive beam, the PETS must produce and efficiently extract a few hundreds MW of R power. O The PETS is a periodically corrugated structure with low impedance (big a/λ). PETS ON/O mechanism Reconstructed from GIL data PETS output pulse envelopes 10 Beam eye view ON Power, norm O Time, ns 8 10