가속기 개발 현황 제 3 회 한국 국제선형가속기 워크숍 (The Third Korean ILC Workshop) 건국대학교 2005 년 4 월 1 일 -4 월 2 일 ILC-Korea Task Force Team PAL/POSTECH 1. ILC-Korea and International Collaboration 2. Modulator R&D

1. ILC-Korea and International Collaboration ILC-Korea Task Force Team, PAL/POSTECH H. Matsumoto, KEK

ILC-Korea Task Force Team at PAL TFT Head: W. Namkung WG1: J. Choi, M.H.Cho WG2: J.S.Oh, W.H.Hwang WG3: S.J.Park, E.S.Kim WG4: J.Y.Huang, H.S.Lee WG5: S.H.Kim, Y.U.Son

- Diagnostics (J. Y. Huang) - Damping Ring (E. S. Kim) - Injector, MBK Development (J. S. Park) - Klystron Power Supply (J. S. Oh) - RF Power Distribution (W. H. Hwang) - Beam Dump (H. S. Lee) - Superconducting Cavity (Y. U. Son) Possible PAL Contributions

Collaboration with PAL/POSTECH 1989: Prof. Won Namkung (PAL) visit KEK to investigate high power klystron for 2-GeV injector linac. We started to collaborate for linac technologies. 1994: Prof. Moo-Hyun Cho (PAL) introduce us a new modulator technology, which use an inverter power supply for the PFN charging. (compact: 48cm x 35cm x 65 cm, stable: +/-0.1%) 1996~1997: Dr. Jong-Seok Oh (PAL) developed a first new klystron modulator (smart modulator No.1) using inverter power supply for the C-band 50-MW klystron. (compact: 1.5m x 2m x 1.2m, low EMI, cost reduction) 2002~2003: We (KEK/RIKEN/PAL) developed second smart modulator, which is oil filled closed metal case. (compact: 1.5m x 1m x 1m, low EMI, low cost) 2003~2004: Shanghai light source group accepted the concept of smart modulator No.1, and made it their self. We are going to collaborate each other for the modulator and brazing technologies as a starting period. H. Matsumoto, KEK

Collaboration with Asian Area for ILC 45 MV/m Possible items are; 1) Power modulator We have developed the first smart modulator with PAL/POSTECH in 1997 at KEK. In 2003, this modulator concept was accepted in China for the Shanghai light source. They fabricated it there themselves, and it was tested in May Also, RIKEN developed an oil-filled closed type modulator, which was evolved from first modulator. We would like to develop the new power modulator, which realize the electric circuit simple, compact size and low cost. 2) Input coupler  very urgent work It was just started to develop the new coupler, which meet an aim of the high gradient acceleration at 45 MV/m. One of key technologies are materials and brazing. We would like to realize structure simple, good reliability and low cost. 3) Waveguide components It was just started only a paper work. So far, waveguide use natural air with atmosphere pressure, which seems to be not enough margin at 5-MW peak rf power and 1-msec pulse width. We would like to develop vacuum type waveguide components, especially circulator. H. Matsumoto, KEK

2. ILC Modulator R&D J. S. Oh, W. Namkung, PAL/POSTECH H. Matsumoto, KEK

TESLA 500/800 RF Requirements

TESLA Energy Upgrade TESLA RF Unit 2 Modulator/Unit 2 Klystron/Unit 3 Cryomodule/Unit Total 1,212 Modulators 1,212 Klystrons 1,818 Cryomodules TESLA RF Unit 1 Modulator/Unit 1 Klystron/Unit 3 Cryomodule/Unit Total 572 Modulators 572 Klystrons 1,716 Cryomodules TESLA RF Unit 3 Modulator/Unit 3 Klystron/Unit 3 Cryomodule/Unit Total 1,818 Modulators 1,818 Klystrons 1,818 Cryomodules

Power Supply for 10 MW Klystron Klystron Gun Voltage 115 (120) kV Klystron Gun Current 130 (140) A HV Pulse Width (70% to 70%)< 1.7 (1.7) ms HV Rise and Fall Time (0 to 90%)<0.2 (0.2) ms HV Flat Top1.37 (1.5) ms Pulse Flatness during Flat Top< ±0.5 (±0.5)% Pulse-to-Pulse Voltage Fluctuation< ±0.5 (±0.5)% Maximum Energy Deposit of Gun Spark < 20 (20) J Pulse Repetition Rate5 (10) Hz Transformer Turn Ration1:12 Filament Voltage9 (11) V Filament Current50 (60) A

Principle of TESLA Modulator Pulse cable : 4 parallel, 6.45 Ohm, max. ~2.8 km Pulse cable : 4 parallel, 6.45 Ohm, max. ~2.8 km Pulser unit : 2.8m(L) x 1.6m(W) x 2.0 m(H) Pulser unit : 2.8m(L) x 1.6m(W) x 2.0 m(H) Pulse transformer tank : 2m(L) x 1.2m(W) x 1.4m(H), 6.5 ton! Pulse transformer tank : 2m(L) x 1.2m(W) x 1.4m(H), 6.5 ton!

New Magnetic Material is available! FINEMET TM : Nano-crystalline Fe-based Soft Magnetic Material with High Saturation Flux Density and Low Core Loss

What is FINEMET? The precursor of FINEMET is amorphous ribbon (non-crystalline) obtained by rapid quenching at one million °C/second from the molten metal consisting of Fe, Si, B and small amounts of Cu and Nb. These crystallized alloys have grains which are extremely uniform and small, “about ten nanometers in size”. Amorphous metals which contain certain alloy elements show superior soft magnetic properties through crystallization. It was commonly known that the characteristics of soft magnetic materials are “larger crystal grains yield better soft magnetic properties”. Contrary to this common belief, soft magnetic material consisting of a small, “nano-order”, crystal grains have excellent soft magnetic properties.

Crystallization Process of FINEMET Amorphous metal as a starting point, Amorphous  Cu-rich area  the nucleation of bcc Fe from Cu bcc  Fe(-Si) shows the crystallization process. At the final stage of this crystallization process, the grain growth is suppressed by the stabilized remaining amorphous phase at the grain boundaries. This stabilization occurs because the crystallization temperature of the remaining amorphous phase rises and it becomes more stable through the enrichment of Nb and B. Synergistic effects of Cu addition, “which causes the nucleation of bcc Fe” and Nb addition, “which suppresses the grain growth” creates a uniform and very fine nano-crystalline microstructure.

Features of FINEMET 1) Satisfy both high saturation magnetic flux density and high permeability High saturation magnetic flux density comparable to Fe-based amorphous metal. High permeability com-parable to Co-based amorphous metal. 2) Low core loss 1/5th the core loss of Fe based amorphous metal and approximately the same core loss as Co-based amorphous metal. 3) Low magnetostriction Less affected by mechanical stress. Very low audio noise emission. 4) Excellent temperature characteristics and small aging effects Small permeability variation (less than  10%) at a temperature range of -50  C~150  C. Unlike Co-based amorphous metals, aging effects are very small. 5) Excellent high frequency characteristics High permeability and low core loss over wide frequency range, which is equivalent to Co-based amorphous metal. 6) Flexibility to control magnetic properties “B-H curve shape” during annealing Three types of B-H curve squareness, high, middle and low remanence ratio, corresponding to various applications

1.Efficiency improvement 2.Pulse transformer with new materials 3.Cost reduction 4.New switching devices 5.New designs 6.Charging supply technology 7.Power distribution 8.Standardization Modulator R&D items