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Optimal design and fabrication of a RF cavity for accelerator mass spectrometry system cyclotron
Ha Donghyup,송호승,Ghergherehchi Mitra,Choi Hyojeong,Shin Seung-wook,Lee Jongchul,Namgoong Ho,Mumyapan Mustafa,채종서 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.8
This study designed a radio frequency (RF) cavity for a cyclotron-based accelerator mass spectrometry (AMS) system. A cyclotron-based AMS system was used to accelerate 12C−, 13C−, and 14C− particles. The experiment results confrmed that three resonant frequencies of the designed RF cavity accelerated the three particles. The RF cavity was a quarter-wavelength resonator (QWR) type and had an external inductor–capacitor (LC) circuit. The operating frequency range of the fabricated RF cavity was 8.5–10 MHz with coupling coefcients of 0.86, 0.99, and 1.11 at resonant frequencies of 8.85, 9.17, and 9.52 MHz, respectively. The refected power at each frequency was less than 1%.
Measurement of Characteristic of X-band RF Cavity for 6 MeV Electron Linac
신승욱,이승현,오세영,Donghyup Ha,Mitra Ghergherehchi,채종서,이병노,채문식 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.7
A compact 6 MeV electron linear accelerator (linac), intended to be used as an X-ray source for a dual-head gantry radiotherapy system has been developed. In order to meet the size requirements of the dual-head gantry machine, an X-band radio frequency (RF) technology is used, which facilitates a reduction in the size of the linac, which is nine times smaller than the conventional medical purpose linac using S-band RF technology. Nevertheless, the X-band RF technology requires much higher machining precision and higher-quality surface finish owing to the electrical breakdown phenomena resulting from its small size. After the design was completed, the RF cavity was machined using high-precision machining technology, achieving machining tolerances of ±2 μm, and a surface roughness less than 50 nm. Various RF properties were measured in the fabricated RF cavity by using a network analyzer, and the distribution of the electric field generated in the RF cavity was verified by a bead-pull measurement technique. RF conditioning and beam commissioning experiments were performed, following the fabrication and tuning of the RF cavity.
SangbumKim,Pham van Duong,Donghyup Ha,Young-Hoon Oh,Won Nam Kang,Seung Pyo Hong,Ranyoung Kim,Jong Seo Chai 한국초전도.저온공학회 2016 한국초전도저온공학회논문지 Vol.18 No.2
Superconducting properties of thin film MgB2 superconductors irradiated with 45 MeV -particle beam were studied. After the irradiation, enhancement of the critical current density and pinning force was observed, scaling close to strong pinning formula. Double logarithmic plots of the maximum pinning force density with irreversible magnetic field show a power law behavior close to carbon-doped MgB2 film or polycrystals. Variation of normalized pinning force density in the reduced magnetic field suggests scaling formulas for strong pinning mechanism like planar defects. We also observed a rapid decay of critical current density as the vortex lattice constant decreases, due to the strong interaction between vortices and increasing magnetic field.
딥러닝 기반 화력발전 보일러 출구 NOx 농도 선행 예측 모델
조현빈(Hyunbin Jo),강동협(Donghyup Kang),박성민(Seongmin Park),이종욱(Jongwuk Lee),류창국(Kang Y. Huh) 한국연소학회 2022 KOSCOSYMPOSIUM논문집 Vol.2022 No.11
In this study, we developed a deep learning model to forecast the NOx and oxygen concentration, and gas temperature at the boiler exit of a coal-fired power plant. The target boiler is a 500 MWe tangential firing boiler, which is one of 20 units often referred to as standard coal power plant. From the database of the power plant, 73 raw items of operation data with one-minute frequency were collected for a period of approximately 5 months. Through the feature selection procedure, the raw data items were condensed into 19 features which include coal feeder throughput to burners, air flow rate, and burner tilt. The features were then used to establish two types of data segments: segment #1 for current operation status and segment #2 for recent histories measured at the boiler exit. Considering the large fluctuations, the histories of the recent values at the boiler exit values were averaged over 5 min. After evaluating different prediction models with respect to the nature of the data segments, suitable models were applied in the form of ensemble model to forecast the boiler exit values 1 min in advance. When compared to measured data, the prediction quality was sufficiently high with a mean square error of 0.0123 for NOx emission.
Design of cyclotron magnet with tenth harmonics for accelerator mass spectrometry
Namgoong Ho,Choi Hyojeong,Ha Donghyup,Ghergherehchi Mitra,Chai J. S.,Lee Jongchul 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.2
In this study, we developed a carbon-beam cyclotron for accelerator mass spectrometry (AMS). A cyclotron magnet for AMS was developed for particle acceleration systems using cyclotrons rather than the tandem accelerator used in conventional accelerator mass spectrometry systems. Design parameters were selected for the development of cyclotrons for AMS, and the magnetic feld design and equilibrium orbit (EO) analysis beam trajectory were analyzed using the Cyclone and CST Microwave Studio. Additionally, by measuring the magnetic feld of the manufactured cyclotron, magnetic feld optimtableization was performed through shimming, and the beam trajectory was verifed based on the measurement results. The cyclotron magnet was designed with a mass resolution of 2890, with harmonic 10 and turn number 92. The minimum turn separation was optimized at 2 mm to reduce the loss caused by the collision of the beam during acceleration. This cyclotron for AMS could accelerate the 12C−, 13C−, and 14C− particles at 40 keV to obtain a beam of 400 keV.
Development of the RF cavity for the SKKUCY-9 compact cyclotron
Shin, Seungwook,Lee, Jongchul,LEE, Byeong-No,Ha, Donghyup,Namgoong, Ho,Chai, Jongseo Elsevier 2015 Nuclear Instruments & Methods in Physics Research. Vol.795 No.-
<P><B>Abstract</B></P> <P>A 9MeV compact cyclotron, named SKKUCY-9, for a radiopharmaceutical compound especially fludeoxyglucose (FDG) production for a positron emission tomography (PET) machine was developed at Sungkyunkwan University. H<SUP>−</SUP> ions which are produced from a Penning Ionization Gauge(PIG) ion source, travel through a normal conducting radio frequency (RF) cavity which operates at 83.2MHz for an acceleration and electro-magnet for a beam focusing until the ions acquire energy of about 9MeV. For installation at a small local hospital, our SKKUCY-9 cyclotron is developed to be compact and light-weight, comparable to conventional medical purpose cyclotrons. For compactness, we adapted a deep valley and large angle hill type for the electro-magnet design. Normally a RF cavity is installed inside of the empty space of the magnet valley region, which is extremely small in our case. We faced problems such as difficulties of installing the RF cavity, low <I>Q</I>-value. Despite of those difficulties, a compact RF cavity and its system including a RF power coupler to feed amplified RF power to the RF cavity and a fine tuner to compensate RF frequency variations was successfully developed and tested.</P>
Kim, Sangbum,Duong, Pham van,Ha, Donghyup,Oh, Young-Hoon,Kang, Won Nam,Hong, Seung Pyo,Kim, Ranyoung,Chai, Jong Seo The Korea Institute of Applied Superconductivity a 2016 한국초전도저온공학회논문지 Vol.18 No.2
Superconducting properties of thin film MgB2 superconductors irradiated with 45 MeV ${\alpha}$-particle beam were studied. After the irradiation, enhancement of the critical current density and pinning force was observed, scaling close to strong pinning formula. Double logarithmic plots of the maximum pinning force density with irreversible magnetic field show a power law behavior close to carbon-doped MgB2 film or polycrystals. Variation of normalized pinning force density in the reduced magnetic field suggests scaling formulas for strong pinning mechanism like planar defects. We also observed a rapid decay of critical current density as the vortex lattice constant decreases, due to the strong interaction between vortices and increasing magnetic field.
Improvement of the RF cavity for the SKKUCY-10 cyclotron
Lee Jongchul,Ghergherehchi Mitra,Gad Khaled M. M.,Ha Donghyup,Namgoong Ho,Lee Seunghyun,Song Ho Seung,Karatas Berat Can,Chai Jong-Seo 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.9
The SKKUCY-10 cyclotron based on 83.2 MHz, 40 kV half-wave RF cavity was developed at Sungkyunkwan University for the production of medical radioisotopes. The resonant frequency fRF of the cyclotron and the RF coupling coefficient βc of the RF cavity system were measured at various vacuum, and temperature conditions. The normalized multi-pacting intensities at four positions in the power coupler were analyzed to predict the multi-pacting power. Differences, ΔfRF and Δβc , caused by the vacuum, and temperature conditions were modified based on the coupler and tuner gap distances. During the RF conditioning, a constant 15 kW pulse mode and a variable 1 to 15 kW continuous wave mode were employed. The values of the reflection coefficient Γ and βc were 1.2% and 0.8, respectively, when the cavity dissipation power was 12.4 kW at 83.2 MHz. Good agreement between the simulation and experimental data was obtained.
X-band Linac for a 6MeV dual-head radiation therapy gantry
Lee, Seung Hyun,Shin, Seung-Wook,Lee, Jongchul,Kim, Hui-Su,Lee, Byeong-No,Lee, Byung-Chul,Park, Hyung-dal,Song, Ki-back,Song, Ho-seung,Mun, Sangchul,Ha, Donghyup,Chai, Jong-Seo Elsevier 2017 Nuclear Instruments & Methods in Physics Research. Vol.852 No.-
<P><B>Abstract</B></P> <P>We developed a design for a 6MeV X-band linear accelerator for radiation therapy in a dual-head gantry layout. The dual-head gantry has two linacs that can be operated independently. Each X-band linac accelerates electron bunches using high-power RF and generates X-rays for radiation therapy. It requires a versatile RF system and pulse sequence to accomplish various radiation therapy procedures.</P> <P>The RF system consists of 9.3GHz, 2MW X-band magnetron and associated RF transmission components. A test linac was assembled and operated to characterize its RF performance without beam. This paper presents these results along with a description of the gantry linacs and their operational requirements.</P>