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Demonstration of the Beam loading compensation

Demonstration of the Beam loading compensation (Preparation status for ILC beam loading compensation experiments at ATF injector in this September) ( PoP experiment on beam loading for truly conventional positron source at ATF injector ).

mandelina-jorgensen
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Demonstration of the Beam loading compensation

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  1. Demonstration of the Beam loading compensation (Preparation status for ILC beam loading compensation experiments at ATF injector in this September) (PoP experiment on beam loading for truly conventional positron source at ATF injector ) AWLC14 at FNAL, 12-16 May 2014 KEK, Junji Urakawa Contents : 1. Short review of conventional positron source for ILC 2. 300Hz Linac Scheme for Beam Loading Compensation using TW. 3. Plan for beam loading compensation experiment at ATF 4. Preparation status 5. Summary

  2. 1. Short reviewof conventional positron source for ILC A conventional positron source for international linear collider, NIM A Volume 672, 21 April 2012, Pages 52-56

  3. 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 0.532A is beam loading current.

  4. 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.

  5. 2. 300Hz Linac Scheme for Beam Loading Compensation Phase to Amplitude Modulation Method for Beam Loading Compensation 300Hz Power Supply Low Level RF Phase Shifter and Amp. 80MW Klystron 3dB High Power RF Combiner 50W High Power Terminator

  6. 3x1010 positron/bunch 300Hz triplet beam Less than +/- 0.7% Beam loading current 0.78A. 300Hz Power Supply 80MW Klystron We need the precise control of the phase shifters. Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50W High Power Terminator 3m long constant gradient travelling wave structure Also, I assume 10% margin as wave guide loss and so on because of the experience at ATF Linac. So, klystron output power 80MW and 3ms pulse width are necessary.

  7. Control of input RF power by phase shifters Detail of beam loading compensation: Less than ±0.7% is possible For ILC 300Hz multi-bunch beam.

  8. 300ns 53.2ns 53.2ns 53.2ns 12.5Hz Power Supply Essential Beam Loading Compensation Scheme for proof-principle experiment at ATF in this September 80MW Klystron Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50W High Power Terminator 3m long constant gradient travelling wave structure 3m long constant gradient travelling wave structure

  9. ATF laser system for photo-cathode RF Gun can generate triplet laser beam of 20 pulse with 2.8ns bunch spacing and about 100ns gap by minor modifications. 357MHz Laser oscillator Pockels cell to make triplet laser pulse train 12.5Hz Amp. 4th higher harmonics generator (crystal:BBO)

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

  11. 1.4x1010 electrons/bunch with 2.8nsec bunch spacing and 2856MHz Linac beam loading current: 0.78A 12.5Hz Power Supply 80MW Klystron Low Level RF Phase Shifter and Amp. We need the precise control of the low level phase shifters. 3dB High Power RF Combiner 50W High Power Terminator 3m long constant gradient travelling wave structure Also, I assume 10%margin as wave guide loss and so on because of the experience at ATF Linac. So, klystron output power 80MW and 3ms pulse width are necessary.

  12. ATF Injector for 1.3 GeV ATF Linac will be modified for beam loading compensation experiment in this summer. 3m long TW 3m long TW Beam Transport 3.6 cell RF Gun 45 degrees bending magnet to measure the energy of multi-bunch 3x1010 with 6.15nsec bunch spacing corresponds to 1.4x1010 in the case of 2.8nsec bunch spacing withsame beam loading in multi-bunch trains. ATF Triplet Beam : 3x20 bunches/train with 60nsec train gap and 2.8nsec bunch spacing. This operation is possible in the safety of the radiation for ATF accelerator. However, since I want to make more safety margin, following doublet beam scheme is proposed.

  13. 166.4ns 53.2ns 53.2ns ~60.0ns 80MW, 4.5ms 12.5Hz Power Supply Essential Beam Loading Compensation Scheme for proof-of-principle experiment at ATF 80MW Klystron Low Level RF Phase Shifter and Amp. 3dB High Power RF Combiner 50W High Power Terminator 3m long constant gradient travelling wave structure 3m long constant gradient travelling wave structure

  14. 12.5Hz Power Supply 12.5Hz Power Supply 80MW, 3ms 40MW, 1.5ms Amplitude Modulation Low Level RF Phase Shifter and Amp. 60MW Klystron 3dB High Power RF Combiner 50W High Power Terminator fast phase control Generation of three mini-train per pulse 45 degrees bending magnet to measure the energy of multi-bunch 3.6 cell RF Gun SW 3m long TW 3m long TW Chicane 150 bunches/pulse with 2.8ns bunch spacing Energy spread 0.1% in rms 2nC/bunch

  15. ATF laser system for photo-cathode RF Gun can generate doublet laser beam of 20 pulse with 2.8ns bunch spacing and about 100ns gap by two Pockels cells. 357MHz Laser oscillator Pockels cell to make doublet laser pulse train 12.5Hz Amp. 4th higher harmonics generator (crystal:BBO) Delay line

  16. Present laser system, Two Pockels cells, 1.6 cell RF Gun, Chicane and BPM were used to generate doublet pulse train and to measure energy of each bunch. 0.78 x1010 electrons per bunch.

  17. Waveguide system should be changed to match the beam loading experiment after summer shutdown of ATF operation. Following plan was proposed and necessary components were ordered. We want to start the change of the waveguide system from mid. of July and will complete it by mid. of August. Present waveguide for KLY#0 Present waveguide for KLY#1 Present waveguide for KLY#2

  18. Present waveguide system KLY#0 KLY#1 KLY#2 New waveguide system for beam loading compensation experiment To L0 To Gun KLY#2 KLY#1 KLY#0 Generation of two mini-train per pulse 45 degrees bending magnet to measure the energy of multi-bunch L0 3m long TW 3.6 cell RF Gun SW 3m long TW Chicane

  19. Several modules and function generators were ordered for the control of RF phase and amplitude which are necessary for the beam loading compensation experiment. We will install necessary control devices and monitor system by mid. of August. Then, we will start the RF aging and test new instrumentation from end of August. I-Q modulation & detection Function Generator

  20. 5. Summary Injector for 1.3GeV ATF Linac will be modified for beam loading compensation experiment in this summer. Due to the lack of 2013 budget, we delayed this experiment, sorry. 3m long TW 3m long TW Beam Transport 3.6 cell RF Gun 45 degrees bending magnet to measure the energy of multi-bunch 2x1010 with 6.15nsec bunch spacing corresponds to 0.9x1010 in the case of 2.8nsec bunch spacing with same beam loading in multi-bunch trains. 3x1010with 6.15nsec bunch spacing corresponds to 1.4x1010 in the case of 2.8nsec bunch spacing with same beam loading in multi-bunch trains.

  21. 80MW, 3ms 12.5Hz Power Supply 40MW, 1.5ms 12.5Hz Power Supply Amplitude modulation Low Level RF Phase Shifter and Amp. 60MW Klystron 3dB High Power RF Combiner 50W High Power Terminator Generation of three mini-train per pulse 45 degrees bending magnet to measure the energy of multi-bunch 3.6 cell RF Gun SW 3m long TW 3m long TW Chicane 150 bunches/pulse with 2.8ns bunch spacing Energy spread 0.1% in rms 1nC/bunch

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