탄뎀형 가속기용 빔 bunching 시스템의 제작 및 설치 I 2003. 4. 26 홍완, 김기동, 김준곤, 최한우, 우형주, 장종화* 한국지질자원연구원 * 한국원자력연구소

연구의 목적 및 개요 자원연의 Tandem 정전형 가속기 (TV = 1.7 MV) 를 단색 중성자 source로 활용을 목적으로 함 (p, n), (d, n) 높은 중성자 에너지 분해능을 얻기 위해 time-of-flight 법을 수행하려면 기존의 연속 빔을 펄스 빔으로 만들 필요가 있음 설계 목표치 - Beam size : 8 mmf 이하 - Bunch width : 1 ~ 2 ns - Bunching yield : 10 ~ 20 % - Bunch repeatation rate : 8 MHz

Concepts of bunching system for negative ion beam

Tandem Accelerator (1.7 MV) of KIGAM

Beam parameters for simulation Initial energy Ion mass Ion valent number Beam half angle in y-direction Beam diameter Initial distribution of ion along to z-direction Number of ions

Bunching system parameters of dimension Deflector - Distance between two electrodes - Length Slit - Position from deflector - Diameter Buncher - Position of electrodes - Length of electrodes - Diameter of electrodes

Bunching system parameters of operation Deflector voltage Buncher voltage Delay time between deflector and bunching electrodes Frequency of deflector voltage Other parameters for simulation Initial phase shift of bias voltage Total elapsed time

Field calculation by Superfish

Bunching system simulation code * : FWTM

Comparison of the bunch histograms

Bunched beam shapes changed along to z-direction

Beam Profile after the buncher x size : 6.98 mm x angle : 1.88 mR y size : 6.24 mm y angle : 5.06 mR

Bending Magnet of Neutron Beam Line

Bending Magnet of Neutron Beam Line

Target Chamber of Neutron Beam Line

Parameter Fitting of Bending Magnet

Characteristics of Neutron Line Angle at Main Magnet : 30  Angle at Neutron Line Bending Magnet : 45  Beam Transmit Ratio at Target Chamber 98 % compared with current after main magnet Vacuum : 1.6 x 10-7 torr Maximum Beam Current : 5 uA for non-bunched proton ? uA for bunched proton Maximum Proton Energy : 3.4 MeV Available Bunched Particle : H+, D+

Bunching Chamber Buncher Deflector

Movable Slit Einzel Lens SNICS Inj. Magnet

RF Power Supply 2 ~ 32 MHz, 300 W

Summary A New beam line for neutron experiment was set up Beam Transmit Ratio : 98 % Vacuum of new line : 1.6 x 10-7 torr after evacuation for 2 days Bunching chamber was installed between injector magnet and accelerator tank Now, RF power supply and control system are being developed The neutron beam of KIGAM is available Pulsed neutron beam is coming soon !!