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Conventional Source for ILC (300Hz Linac scheme and the cost) Junji Urakawa, KEK LCWS2012 Contents : 0. Short review of 300Hz conventional positron source 1. 300Hz Linac Scheme for Beam Loading Compensation 2. Cost 3. Plan for beam loading compensation experiment at ATF

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The baseline choice of the ILC positron source is the helical undulator scheme. After accelerating the electron beam in the main linac, it passes a 150 m long helical undulator to create a circularly polarized photon beam, and goes to the interaction point. The photon beam hits the production target and generates electron–positron pairs. The positrons are captured, accelerated to 5 GeV, damped, and then accelerated to the collision energy in the main linac. Thus the undulator based positron generation gives interconnection to nearly all sub-systems of the ILC. The proposed ILC positron source contains risks only in the target area. As for the conventional positron source, we concentrate to cure these risks in two ways: (1)pulse stretching by 300 Hz generation; the proposed scheme creates 2600 bunches in about 60 ms, and (2) optimized drive beam and target thickness parameters. Following design is the backup for proposed ILC positron source. From T. Omori et al. / NIMA 672 (2012) 52–56 0. Short review of 300Hz conventional positron source

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Time structure of beam 0<t<264.45ns, i=0.532A 264.45<t<362.85ns, 0A 362.85ns<t<627.3ns, 0.532A 627.3ns<t<725.7ns, 0A 725.7ns<t<990.15ns, 0.532A

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Bunch by bunch extraction from Damping Ring to make ILC beam train. This is the model for positron target system to confirm the generation of ILC positron beam.

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Abstract of the paper. A possible solution to realize a conventional positron source driven by a several-GeV electron beam for the International Linear Collider is proposed. A 300 Hz electron linac is employed to create positrons with stretching pulse length in order to cure target thermal load. ILC requires about 2600 bunches in a train which pulse length is 1 ms. Each pulse of the 300 Hz linac creates about 130 bunches, then 2600 bunches are created in 63 ms. Optimized parameters such as drive beam energy, beam size, and target thickness, are discussed assuming a L-band capture system to maximize the capture efficiency and to mitigate the target thermal load. A slow rotating tungsten disk is employed as positron generation target.

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Phase to Amplitude Modulation Method for Beam Loading Compensation 200MW, 3 s 300Hz Power Supply Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50 High Power Terminator 80MW Klystron Speed of phase control is about 100 degrees/10ns.

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Q0=13000 R0=60MOhm One accelerator unit for 6GeV Electron Drive Linac

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One accelerator unit for 5GeV Positron Linac

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Total 26793MYen for 6GeV and 5GeV S-band 300Hz Linac

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200MW, 3 s 300Hz Power Supply Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50 High Power Terminator 80MW Klystron 3m long constant gradient travelling wave structure We do not need the system of correction structure for beam loading compensation. We need the precise control of the phase shifters. Also, I am researching the time structure of RF power feeding to increase energy gain and decided 20% of the margin +wave guide loss is too much and we can reduce it to 10% because of the experience at ATF Linac. 3x10 10 positron/bunch 300Hz triplet beam Less than +/- 0.7%

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6GeV Drive Linac with 2x10E10 e/bunchunit :M\5GeV Positron Linac with 3x10E10 e/bunchunit :M\ 38 RF units36 RF units 2 main klystrons x 38 with 10% margin and 10% loss02 main klystrons x 36 with 10% margin and 10% loss0 2.6GHz 64MW at RF cavity, total 76 Klystrons17482.6GHz 64MW at RF cavity, total 72 Klystrons1656 number of 3m long cavities, total 76 structures1157number of 3m long cavities, total 72 structures1096 2 phase shifters x 38, total 76 phase shifters382 phase shifters x 36, total 72 phase shifters36 HP combinor x 38130HP combinor x 36120 3dB divider x 38703dB divider x 3666 waveguide x 3820waveguide x 3620 2 modulators x 38, total 76 modulators39522 modulators x 36, total 72 modulators3744 Computor Control Unit x 3830Computor Control Unit x 3630 2 correction klystrons x 38 with 10% margin and 10% loss02 correction klystrons x 36 with 10% margin and 10% loss0 2.6GHz 64MW at RF cavity, total 76 Klystrons17482.6GHz 64MW at RF cavity, total 72 Klystrons1656 number of 0.33m long cavities, total 76 structures468number of 0.33m long cavities, total 72 structures443 2 phase shifters x 38, total 76 phase shifters382 phase shifters x 36, total 72 phase shifters36 HP combinor x 38130HP combinor x 36120 3dB divider x 38703dB divider x 3666 waveguide x 3820waveguide x 3620 2 modulators x 38, total 76 modulators39522 modulators x 36, total 72 modulators3744 Computor Control Unit x 3830Computor Control Unit x 3630 35 quads3534 quads34 27 horizontal steerings1026 horizontal steerings10 27 vertical steerings1026 vertical steerings10 power supplies for magnets50power supplies for magnets50 beam monitor devices50beam monitor devices50 1375613037 26793M\-12571M\=14222M\, which is 142 Oku-Yen for 300Hz 6GeV Drive Linac and 5GeV positron Linac.

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6GeV Drive Linac with 2x10 10 electrons/bunch 38 RF units 2 main klystrons (x 38) with 10% margin and 10% loss 2.6GHz 64MW at RF cavity (total 76 klystrons) 1748 number of 3m-long cavities (total 76 structures) 1157 2 phase shifters (x 38, total 76 phase shifters) 38 HP combinor (x 38) 130 3dB divider (x 38) 70 waveguide (x 38) 20 2 modulators (x 38, total 76 modulators) 3952 Computor Control Unit (x 38) 30 2 correction klystrons x 38 with 10% margin and 10% loss 2.6GHz 64MW at RF cavity (total 76 Klystrons) 1748 number of 0.33m long cavities (total 76 structures) 468 2 phase shifters (x 38, total 76 phase shifters) 38 HP combinor (x 38) 130 3dB divider (x 38) 70 waveguide (x 38) 20 2 modulators (x 38, total 76 modulators) 3952 Computor Control Unit (x 38) 30 35 quads 35 27 horizontal steerings 10 27 vertical steerings 10 power supplies for magnets 50 beam monitor devices 50 total 13756 26793M\-12571M\= 14222M\, which is 142 Oku-Yen for 300Hz 6GeV Drive Linac and 5GeV positron Linac. 6456 saved

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5GeV Positron Linac with 3x10 10 positrons/bunch 36 RF units 2 main klystrons x 36 with 10% margin and 10% loss 2.6GHz 64MW at RF cavity (total 72 Klystrons) 1656 number of 3m long cavities (total 72 structures) 1096 2 phase shifters (x 36, total 72 phase shifters) 36 HP combinor (x 36) 120 3dB divider (x 36) 66 waveguide (x 36) 20 2 modulators (x 36, total 72 modulators) 3744 Computor Control Unit (x 36) 30 2 correction klystrons x 36 with 10% margin and 10% loss 2.6GHz 64MW at RF cavity (total 72 Klystrons) 1656 number of 0.33m long cavities (total 72 structures) 443 2 phase shifters (x 36, total 72 phase shifters) 36 HP combinor (x 36) 120 3dB divider (x 36) 66 waveguide (x 36) 20 2 modulators (x 36, total 72 modulators) 3744 Computor Control Unit (x 36) 30 Total 26793MYen for 6GeV and 5GeV S-band 300Hz Linac, Total 26993 Myen 34 quads 34 26 horizontal steerings 10 26 vertical steerings 10 power supplies for magnets 50 beam monitor devices 50 total 13037 26793M\-12571M\= 14222M\, which is 142 Oku-Yen for 300Hz 6GeV Drive Linac and 5GeV positron Linac. 6115 saved

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200MW, 3 s 12.5Hz Power Supply Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50 High Power Terminator 80MW Klystron 3m long constant gradient travelling wave structure Essential Beam Loading Compensation Scheme

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Photo-cathode RF gun (electron source) S-band Linac Extraction line Damping Ring Plan for beam loading compensation experiment at ATF

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3.6 cell RF-Gun started beam acceleration test from 1/11,2012. 11MeV beam at 120MV/m, from 100bunches/pulse to 1000bunches/pulse beam generation 9.6MeV beam in a week RF aging with ~20.3MW RF input power Two years ago In this year 3.6 cell RF Gun Installation Now, 10MeV multi - bunch trains are generated and accelerated. With RF amplitude modulation And without beam Energy of multi-bunch beam

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Phase to Amplitude Modulation Method for Beam Loading Compensation 200MW, 3 s 300Hz Power Supply Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50 High Power Terminator 80MW Klystron Speed of phase control is about 100 degrees/10ns.

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200MW, 3 s 300Hz Power Supply Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50 High Power Terminator 80MW Klystron 3m long constant gradient travelling wave structure We do not need the system of correction structure for beam loading compensation. We need the precise control of the phase shifters. Also, I am researching the time structure of RF power feeding to increase energy gain and decided 20% of the margin +wave guide loss is too much and we can reduce it to 10% because of the experience at ATF Linac. 0.9x10 10 electrons/bunch With 2.8nsec bunch spacing And 2856MHz Linac

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3.6 cell RF Gun 3m long TW 2x10 10 with 6.15nsec bunch spacing corresponds to 0.9x10 10 in the case of 2.8nsec bunch spacing as same beam loading in multi-bunch trains. ATF Triplet Beam : 10 bunches/train with 30nsec train gap And 2.8nsec bunch spacing 90 degrees bending magnet to measure the energy of multi-bunch Beam Transport ATF Injector for 1.5GeV ATF Linac will be modified for beam loading compensation experiment in next year.

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From NIM A 560 (2006) 233–239. S-band RF Gun, more than 100MV/m Operation:120MV/m,max.:140MV/m 250mm 1.6 cell RF Gun already Demonstrated Multi-bunch Beam loading Compensation.

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Thank you. We should make the demonstration experiment for the improvement of Linac acceleration techniques at ATF Linac. 10mA at STF-QB Achieved ~7mA FLASH 9mA

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