CLIC Feasibility Demonstration at CTF3 Roger Ruber Uppsala University, Sweden, KVI Groningen 20 Sep 2011 20 Sep 2011
The Key to CLIC Efficiency • NC Linac for 1.5 TeV/beam Main Linac – accelerating gradient : 100 MV/m C.M. Energy 3 TeV – RF frequency: 12 GHz 2x10 34 cm -2 s -1 2x10 34 cm 2 s 1 Peak luminosity Peak luminosity • Total active length for 1.5 TeV: 15 km Beam Rep. rate 50 Hz individual klystrons not realistic Pulse time duration 156 ns • Two-beam acceleration scheme Average gradient 100 MV/m • Luminosity of 2x10 34 cm -2 s -1 # cavities 2 x 71,548 – short pulse (156ns) p ( ) – high rep-rate (50Hz) – very small beam size (1x100nm) • 64 MW RF power / accelerating structure of 0.233m active length 275 MW/m • Estimated wall power 415 MW at 7% efficiency Estimated wall power 415 MW at 7% efficiency Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 2
CLIC Layout Drive Beam Drive Beam Generation Generation Complex Complex Drive Beam Drive Beam Main Beam 3 TeV (CM) Main Beam 3 TeV (CM) Main Beam Main Beam Generation Generation Complex Complex Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 3
CLIC Two-beam Acceleration Scheme Drive Beam Accelerator Delay Loop (2x) efficient acceleration in fully loaded linac gap creation, pulse compression & frequency multiplication Combiner Ring (4x) RF Transverse pulse compression & Deflectors frequency multiplication Combiner Ring (3x) C bi Ri (3 ) pulse compression & frequency multiplication RF Power Source Drive Beam Decelerator (24 in total) Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 4
CLIC Test Facility CTF3 • Drive beam generation , with – appropriate time structure, and – fully loaded acceleration • Two-beam acceleration , with CLIC prototype (TBTS) CLIC prototype (TBTS) Delay Loop – accelerating structures Combiner – power production power production Ring Ring Drive Beam D i B structures (PETS) Linac • Deceleration stability CALIFES Probe Beam Linac Probe Beam Linac (TBL) Two-beam Test Stand • Photoinjector (PHIN) Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 5
CTF3 Experimental Program • Two-beam acceleration – conditioning and test PETS and accelerating structures – breakdown kicks of beam breakdown kicks of beam – dark (electron) current accompanied by ions – install 1, then 3, two-beam modules • Drive beam generation • Drive beam generation TBTS is the only place – phase feed forward for phase stability available to investigate – increase to 5 Hz repetition rate effects of RF breakdown – coherent diffraction radiation experiments coherent diffraction radiation experiments on the beam on the beam • Drive beam deceleration – extend TBL to 8 then 16 PETS – high power production + test stand • 12GHz klystron powered test stand – power testing structures w/o beam – significantly higher repetition rate (50 Hz) Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 6
The CTF3 Facility as CLIC Test Bench 48.3 km 48 3 km Delay loop Drive beam Combine X4 r ring Probe beam Probe beam 12 GHz Stand alone Test-stand Test Beam Line 12 GHz Stand-alone Test Stand Two-beam Test Stand Test beam Line 140 m Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 7
CTF3 Drive Beam • Several operation modes possible, • Tail clipper (TC) after the CR to adjust the pulse length, length • Upgrade possible to 150 MeV at 5 Hz repetition rate. Mode #1 #2 #3 Energy 120 [MeV] Energy spread Energy spread 2 2 [%] [%] Current (1) 30 15 4 [A] Pulse length (2) 140 240 1100 [ns] DBA frequency DBA frequency 1 5 1.5 3 3 3 3 [GHz] [GHz] Bunch frequency 12 12 3 [GHz] Repetition rate 0.8 [Hz] PETS power PETS power 200 200 61 61 5 5 [MW] [MW] Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 8
Demonstration Fully Loaded Operation Efficient power transfer • “Standard” situation: • • small beam loading small beam loading • power at exit lost in load • “Efficient” situation: V ACC ≈ 1/2 V unloaded • high beam loading high beam loading • no power flows into load 95.3% RF % ut Pou power to beam field builds up linearly (and stepwise, for point-like bunches) Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 LINAC'10 (13-Sep-2010) 9
Recombination Principle D l Delay Loop L even buckets odd buckets RF deflector C Combiner Ring bi Ri 4 th Turn DELAY LOOP 4 A – 1.2 s COMBINER 150 Mev RING DRIVE BEAM LINAC 32 A – 140 ns 150 Mev CLEX 10 m CLIC Experimental Area /4 o /4 Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 10
Bunch Re-combination DL + CR • Streak camera From DL Turn 1 images from CR Turn 2 Turn 2 • bunch spacing: – 666 ps initial Turn 3 – 83 ps final 83 fi l Turn 4 • circulation time correction by wiggler adjustment by wiggler adjustment • Signal from BPMs from Linac Signal from BPMs in DL DL CR after DL 30A 30A in CR Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 11
Ongoing Work • Beam current stabilization LINAC DL CR – CLIC requires stability at 0.075% level 0.13% 0.20% 1.01% Variation – ok from linac and DL ok from linac and DL need improvement in CR • Phase stabilization – temperature stabilization t t t bili ti pulse compressor cavity • Transfer line commissioning – transport losses from CR to experiment hall RF phase stability along pulse l l klystron off (for different ambient temperatures) Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 12
CALIFES Probe Beam • A standing-wave photo-injector g p j Energy 200 MeV Energy spread 1% (FWHM) • 3 travelling-wave structures, the first one Pulse length 0.6–150 ns used for velocity bunching Bunch frequency 1.5 GHz Bunch length 1.4 ps • A single klystron (45 MW – 5.5 ms) with • A single klystron (45 MW 5 5 ms) with Bunch charge Bunch charge 0.085 0.6 nC 0 085–0 6 nC Intensity pulse compression (120 MW – 1.3 ms) - short pulse 1 A - long pulse 0.13 A • A RF network with splitters, phase shifters, Repetition rate 0.833 – 5 Hz attenuator, circulator and couplers tt t i l t d l Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 13
Two-beam Test Stand S Spectrometers t t Experimental area and beam dumps Construction supported by the Swedish Research Council and the Council and the Knut and Alice Wallenberg Foundation Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 14
Two-beam Test Stand Prospects Versatile facility • two-beam operation – 28A drive beam [100A at CLIC] 28A drive beam [100A at CLIC] – 1A probe beam [like CLIC ] • excellent beam diagnostics, long lever arms • easy access & flexibility for future upgrades Unique test possibilities • power production in prototype CLIC PETS p p p yp • two-beam acceleration and full CLIC module • studies of – beam kick & RF breakdown beam kick & RF breakdown – beam dynamics effects – beam-based alignment Roger Ruber (Uppsala University) - CLIC Feasibility Demonstration at CTF3 KVI, 20-Sep-2011 15
TBTS Test Area 1x PETS w/ recirculation 11 March 2010 11 March 2010 RR201003110009 1x accelerating g structure Roger Ruber (Uppsala University) - Two-beam Test Stand CTF3 Collaboration Meeting (05- 16 May-2010)
Structures Test Program • Drive Beam Area – Installed: • TBTS PETS, 1m long • external RF power recirculation – Next test foreseen: • PETS On/Off option (active reflector) A C A. Cappelletti (04-May-2010) ll tti (04 M 2010) 4 th X-band Workshop Courtesy A. Cappelletti http://indico.cern.ch/event/75374 • Probe Beam Area Probe Beam Area – Installed: • TD24 = disks, tapered, damped, 24 cells A. Samoshkin (07-Apr-2010) CLIC RF struct. dev. meeting http://indico.cern.ch/event/72089 – Next test foreseen: • TD24 with wakefield monitor • TD24 with wakefield monitor Courtesy A. Samoshkin Roger Ruber (Uppsala University) - Two-beam Test Stand CTF3 Collaboration Meeting (05- 17 May-2010)
PETS Power Recirculation • PETS length 1m, to compensate for lower to load beam current compared to CLIC variable splitter variable (coupling: 0 1) phase shifter • External recirculation loop External recirculation loop PETS output – increase PETS power in long pulse, PETS input drive low current mode #3 beam • power recirculation i l ti through external feedback loop: – electron bunch generates field burst generates field burst – field burst returns after roundtrip time t r = 26ns PETS operates as amplifier (LASER like) • phase shifter to adjust phase error in the loop Roger Ruber (Uppsala University) - Two-beam Test Stand CTF3 Collaboration Meeting (05- 18 May-2010)
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