Development of 1-MeV L-bandL Electr Linac for CESC * 양해룡 #, 김상훈, 장성덕 1), 손윤규 1), 권세진 1), 박성주 1), 오종석 1), 조무현, 남궁원포항공과대학교물리학과, 1) 포항가속기연구소 한국물리학회가을학술논문발표회 27년 1월 18~19일, 제주 *Work supported by KAPRA, # highlg@postech.ac.kr 1/21
Introducti L-band traveling-wave electr linac Irradiati applicatis 1 MeV and average 3 kw Single klystr (pulsed 25 MW) Single accelerating column Vertical mount 2/21
Accelerator Parameters Operating Frequency Pulsed RF Power Pulse Length Repetiti Rate Average RF Power High Voltage Pulsed Beam Current Pulse Length RF System Parameter E-gun Parameter 1.3 GHz 25 MW 7 μs 35 Hz 6 kw 8 kv 1.6 A 6 μs Beam Energy Pulsed Beam Current Beam Transmissi Rate Average Beam Power Type of Structure Shape of Cell Operating Mode RF Filling Time Accelerating Structure Parameter Operating Temperature Average Accelerating Gradients Beam Loading Factor Temperature Shift Factor Beam Parameter 1.7 MeV 1.4 A 9% 35 kw Cstantimpedance Disk-loaded 2π/3 mode.8 μs 4 C ± 1 C 4.2 MV/m - 4.7 MeV/A - 2.3 MeV/ C 3/21
System Layout To be installed at CESC (Cheorw Electr-beam Service Center) Accelerator E-gun Pulser Temp. Ctroller Waveguide Klystr Modulator CCPS & Ctrol Panel 4/21
Schematic Diagram of Linac System Inverter Master Trigger Modulator Cooling Stand Source RF Generator Klystr Cooling Water Distributor E-gun HV Pulser E-gun Heater PS ATT PS RF Window IP Vacuum Gauge Ctroller IP Ctroller RF Window IP Load Beam Diagnostics System Beam Scanner BEM E-Gun PB Accelerating Column BCM IP PGV Temperature Ctroller PGV IP Ctroller Vacuum Gauge Ctroller Solenoid Magnet PS Steering Coil Ctroller PB: Pre-buncher PGV: Pneumatic Gate Valve ATT: Attenuator BCM: Beam Current Mitor IP: I Pump PS: Phase Shifter BEM: Beam Energy Mitor 5/21
Beamline Cfigurati Ir-wrapped Solednoids Magnet E-gun Steering coil PGV Pre-buncher Solenoids Magnets Accelerating Column Vacuum System RF Window Waterload BCM PGV The beam scanner system is followed by this drift tube. 6/21
Accelerating Column Bunching Secti Normal Secti Cell Characteristics 5 4 Phase shift for cavity cell Cumulative phase shift for per cell relative to No. Cell 1 st buncher 2 nd buncher 3 rd buncher 4 th buncher 5 th buncher Normal Phase velocity / c.65.75.88.92.98 1. Attenuati Coefficient (Nep/m).538.489.442.431.415.623 RF Phase Deviati (deg.) 3 2 1-1 -2-3 -4-5 5 1 15 2 25 3 Cavity Cell Number 7/21
RF Couplers Measurement Setup (Khyl s mothod TRwave coupler) Impedance Smith-chart to Coax adapter Network analyzer (Agilent E8362B) z ( ω 2) 2 π / Tapered 1 2 Shorting bar z ( ω ) 2 m ϕ( ω m ) ϕ( ω π / 2) ϕ( ω 2π / 3) z 1 ( ω) ω = ( ω π + ω 3) / 2 m ϕ( ω ) π / 2 ϕ( ω m ) ϕ( ω 2π / 3) / 2 2π / Input coupler 12.1 179.2-119.9 Output coupler 117.7 179.4-12.6 z ( ω 3) 2 2π / 8/21
Focusing Solenoids Lgitudinal Magnetic Field (G) 15 125 1 75 5 25 Lgitudial B-filed 5 1 15 2 25 3 1 2 3 4 5 Lgitudinal Distance (cm) Solenoids Characteristics Solenoid s 1 2 3 4 5 Ampereturn 2 32 36 44 44 Current (A) 3.6 32 32 32 32 Powered by single DC power supply 9/21
Waveguide Network with Coax Line e-gun L-band Waveguide Network Prebuncher Coax. D/C Variable ~53 db Φ-Shifter Low loss Dielectric Coaxial Cable ( ~4 m lg) Variable Attenuator Compents inside the red boxes are filled with SF6 gas. Vacuum Pumping port RF Window [Thales] -D/C 7 db Straight Secti E-bend Arc Sensing View Port L-band Accelerating Column [IHEP in China] Compents inside the blue boxes are operated under vacuum. High-power Load Straight Secti -D/C 7 db Gas Feeding Port RF power 25 MW-pulsed 6 kw-average Klystr Output -Coax Cverter CX-DC 38 db Straight Secti Gas Feeding Port -D/C 7 db E-bend Arc Sensing View Port Vacuum Pumping port RF Window [Thales] E-bend Arc Sensing View Port Low- power Load e-beam 1/21
Klystr Thales TV222D Tube Specificatis Frequency RF output peak power RF output average power Peak drive power RF pulse durati Cathode voltage Beam current Perveance Heater 1.3 GHz 3 MW 6 kw 3 W 7 us 264 kv 23 A 1.7 μperv 28 V / 25 A 1 : 13 Pulse Transformer 11/21
Pulse Modulator Number of Stages Capacitor Inductor 15 stages 5 nf 2.2 μh Peak Charging Rate 33 kj/sec 1: 13 Output Voltage Average Output Power Number of Units 45 kv 3 kw 8 units CX2412X Peak forward voltage Peak forward current Average anode current 5 kv max 15 ka max 15 A max 12/21
High-voltage Pulse Test Load beam voltage Test Result 247.72 kv 246.4 A Load beam Current Load Impedance Load Voltage Load Current Charging Voltage Pulse Width (7 %) Repetiti Rate 1 kω 247.72 kv 246.4 A 42 kv 9.3 μs 1 Hz 2 4 6 8 1 Time (μs) 12 13/21
Ctrol System Remote PC Accelerator Ctrol RS485 Power Detector - 1R Arc Detector -1, 2, 3 E-gun HV Pulser E-gun Heater PS F S F F Master Trigger Main F F S Modulator Ctrol Cooling water Ctrol PGV - 1,2 S F PGV Ctroller F Vacuum Guage Ctroller S Ctrol S Cveyor belt Ctrol Solenoid Magnet PS Steering Coil PS IP Ctroller BCM Power Detector - 1F, 2, 3 S S S S Radiati & Protecti Ctrol Ctrol Interlock Mitoring 14/21
Beam Commissiing Scenario Step Steering Coils Solenoids Input RF Power (into acc.) Input Current (A) Prebuncher Remarks Goal (transmissi) 1. Initial Cditi.1 Check the output beam current. 2. Alignment Check.1 Search the max. transmissi cditi of the steering coils. Find the set rate. 87% 3. Solenoids On re-adjust.1 Turn the solenoids. Adjust the steering coil refer to the simulati result. 1% 4. RF On to 12 MW.1 Raise the input power Until the output beam energy is 1 MeV. 85% 5. Nominal Current 12 MW to 1.6 Raise the input current at the operati cditi. 86% 6. Nominal RF Power to 25 MW 1.6 Raise the input power until the output beam energy at the operati cditi. 77% 7. Operati Cditi 25 MW 1.6 Obtain the optimum cditi by the commissiing of the pre-buncher. 89% 15/21
Beam Commissiing Alignment Check 1 Input beam current:.1 A 1 Input beam current:.1 A.9.9.8.8 Transmissi rate.7.6.5.4.3 Transmissi rate.7.6.5.4.3.2.2.1.1.2.4.6.8 1 Misalignment angle (deg.).2.4.6.8 1 R-directi E-gun positi set (cm) Initial cditi: no power, no solenoid, no pre-bunching, operati the E-gun emitting.1 A ly 1 misalignment no output beam Steering coils find the value of the misalignment 16/21
Beam Commissiing Solenoids On x, y positi (cm) 2 1.5 1.5 -.5-1 x mean x 99% x 1% y mean y 99% y 1% Beam Size 5 1 15 2 25 3 35 Lgitudinal positi (cm) 1 misalignment, solenoils -1.5 x, y positi (cm) -2 2 1.5 1.5 -.5-1 x mean x 99% x 1% y mean y 99% y 1% Beam Size 5 1 15 2 25 3 35 Lgitudinal positi (cm) Re-adjusted by steering coils -1.5-2 Focusing by solenoids 1% transmissi Re-adjusted by steering coils refer to simulati result Optimum cditi 17/21
Beam Commissiing RF On 1.95 Transmissi Energy (MeV) Input beam current:.1 A 18 16 14 Transmissi.9.85.8.75.7 12 1 8 6 4 2 5 1 15 2 25 Input Power (MW) Energy (MeV) Raise the RF power at 12 MW : Beam energy limited by 1 MeV due to neutr producti 18/21
Beam Commissiing Nominal Cditi.9 Input RF power: 12 MW 1.9 Input current: 1.6 A 16.88 nominal value 8.85 12 Transmissi rate.86.84 6 4 Energy (MeV) Transmissi rate.8 nominal value 8 Energy (MeV).82 2.75 4 Transmissi Transmissi.8 Energy (MeV).4.8 1.2 1.6 2 Input Current (A).7 Energy (MeV) 12 15 18 21 24 27 3 Input Power (MW) Raise the input current to nominal value: 1.6 A Raise the RF power to nominal value: 25 MW 19/21
Beam Commissiing Operati Cditi 16 max. power point Input current: 1.6 A Pre-buncher input power: 3.75kW 1 14 Energy (MeV), Power (MW) 12 1 8 6 4 2 Energy (25MW, 1.6A) Power (25MW, 1.6A) Transmissi rate.8.6.4.2 Transmissi rate 6 12 18 24 3 36 Phase difference ( ) Scanning the transmissi rate during change the pre-buncher phase Pre-buncher optimizing Δφ PB 1, transmissi 9%, 1.7 MeV 2/21
Current Status and Plan Klystr & Modulator Fabricati and Assembling finished. PFN to be tuned for the flat-top requirement. Installed at the CESC site. Waveguide and Coaxial-line Ready to installati. Accelerating Column Delivered to Pohang. Beamline also to be assembled. Under Development Beam Scanner Cooling System Ctrol System Commissig is planned this year. 21/21