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209 results on '"Kang, Hyoungku"'

7. Electromagnetic Characteristics of a Superconducting Magnet for 28GHz ECR Ion Source according to the Series Resistance of a Protection Circuit

Author

Lee, Hongseok, Mo, Young Kyu, Lee, Onyou, Kim, Junil, Bang, Seungmin, Kang, Jong O, Hong, Jonggi, Nam, Seokho, Choi, Sukjin, Hong, In Seok, Ahn, Min Chul, and Kang, Hyoungku

Subjects
Physics - Accelerator Physics
Abstract

A linear accelerator, called RAON, has been being developed as a part of Rare Isotope Science Project (RISP) by Institute for Basic Science (IBS) [1]. The linear accelerator utilizes an electron cyclotron resonance (ECR) ion source for providing intense highly charged ion beams to the linear accelerator. 28GHz ECR ion source can extract heavy ion beams from proton to uranium. A superconducting magnet system for 28GHz ECR ion source is composed of hexapole coils and four solenoid coils made with low Tc superconducting wires of NbTi [2]. The electromagnetic force acts on the superconducting magnets due to the magnetic field and flowing current in case of not only normal state but also quench state [3]. In case of quench on hexapole coils, unbalanced flowing current among the hexapole coils is generated and it causes unbalanced electromagnetic force. Coil motions and coil strains in quench state are larger than those in normal state due to unbalanced electromagnetic force among hexapole coils. Therefore, analysis on electromagnetic characteristics of superconducting magnet for 28GHz ECR ion source according to the series resistance of protection circuit in case of quench should be conducted. In this paper, analysis on electromagnetic characteristics of superconducting hexapole coils for 28GHz ECR ion source according to the series resistance of protection circuit in case of quench is performed by using finite elements method (FEM) simulation.

Published
2015

12. Development of a 5-Axis Winding Method for Saddle-Shaped Coils Using Coated ReBCO High Temperature Superconductors

Author

Yang, Seongjin, Song, Woojin, Park, Jeonghwan, Kim, Geonyoung, Huang, Jung Yun, Hahn, Seungyong, Choi, Seyong, Kang, Hyoungku, and Hahn, Garam

Abstract

Saddle-shaped superconducting coils are efficient in terms of generating an ideal multipole field inside a cylindrical bobbin which is the typical shape used in particle accelerators, electric motors, nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), and other application. Compared to low-temperature superconductors, rare earth barium copper oxide (ReBCO) high-temperature superconductor (HTS) wires exhibit excellent electromechanical behavior, high current carrying capacity to generate high magnetic fields and high thermal stability to reduce cooling costs. Despite such advantages, attempts to wind a saddle-shaped coil by using the coated HTS conductor have been rarely reported due to a hard-way bending characteristics of the thin tape-shaped HTS conductor. Here, we introduce the concept of a dedicated winding machine capable of winding saddle-shaped coils including the numerical modelling and visualization. To simplify the implementation of the winding machine, we utilized one universal joint and two 2D linear stages. We also derived control variables that can be directly applied in practical operations.

Published
2024
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13. Distributed-Circuit Method for Replication of Fast-Ramping of Saddle-Shaped REBCO Dipole Magnet Wound With Two-Tape Bundled Conductor

Author

Kim, Geonyoung, Park, Hyunsoo, Im, Chaemin, Park, Jeonghwan, Koo, Jaheum, Jung, Wonju, Lee, Jung Tae, Jang, Wonseok, Cha, JuKyung, Yan, Yufan, Kim, Jaemin, Bang, Jeseok, Hahn, Garam, Choi, Seyong, Kang, Hyoungku, and Hahn, Seungyong

Abstract

This work presents a distributed-circuit model for analyzing experimental results of fast-ramping behaviors of a saddle-shaped REBCO dipole magnet wound with a bundled conductor. Terminal voltage and center magnetic field were measured during the test performed at 77 K temperature. Our distributed-circuit model accurately reproduced the observed electromagnetic behaviors, demonstrating its validity for the fast-ramping operation of an HTS magnet. We also analyzed the current discrepancy between bundled conductors and Joule dissipation due to the various ranges of contact resistivity.

Published
2024
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14. Experimental Study for Modified Lumped-Circuit Model to Analyze Saddle-Shaped No-Insulation HTS Coil Operated in Overcurrent Situation

Author

Kim, Geonyoung, Jung, Wonju, Koo, Jaheum, Park, Jeonghwan, Park, Hyunsoo, Cha, JuKyung, Lee, Jung Tae, Jang, Wonseok, Park, Seong Hyeon, Yan, Yufan, Kim, Jaemin, Bang, Jeseok, Hahn, Garam, Choi, Seyong, Kang, Hyoungku, Hahn, Seungyong, and Lee, Sangjin

Abstract

This work presents a modified lumped-circuit model for a saddle-shaped no-insulation (NI) high temperature superconductor (HTS) coil in overcurrent, which is defined by the situation that azimuthal current is close to or greater than the critical current. We suggested the variation of the coil's circuit parameters, such as inductance, ‘index’ resistance, and characteristic resistance. We modified the base assumptions of the conventional lumped-circuit model and experimented to validate the suggested model. An 82-turn saddle-shaped NI coil was fabricated, and terminal voltage and magnetic field were measured during the overcurrent test in a 77 K liquid nitrogen bath. Compared to the conventional model, our modified lumped-circuit model reduced the error between measurement and simulation from 44.2% to 2.9%. We inversely calculated the variation of circuit parameters and magnet constant, which cannot be the constant value, and the results are presented.

Published
2024
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15. Electrical Breakdown Characteristics in High-Vacuum Conditions for the Design of Superconducting Coils

Author

Park, Junyoung, Shin, Woocheol, Jeong, Minkyung, Ku, Bonhyuk, Lee, Hobin, Park, Jeonghwan, Hahn, Garam, Choi, Seyong, Hahn, Seungyong, and Kang, Hyoungku

Abstract

In recent years, the utilization of high-temperature superconductors (HTS) in medical devices, such as magnetic resonance imaging (MRI) and particle accelerators for cancer treatment, has seen significant growth. This study focuses on the electrical insulation design of fast-ramping HTS saddle magnets, pivotal in reducing the volume and consequent operational costs of particle accelerators. Generally, these HTS magnets are operated under high-vacuum conditions to deter external heat intrusion and optimize thermal efficiency. However, their intricate geometries can inadvertently result in areas of localized vacuum degradation, undermining their electrical insulation capabilities, especially in environments with pressures less than 0.001 Pa. Further, this research delves into the influence of vacuum degree and insulator surface roughness on the electrical breakdown properties. The focus is primarily on the distinctions between sparkover and flashover. Due to their fast-ramping nature, HTS magnets undergo substantial current changes in short durations, leading to the induction of potentially dangerous voltages that might trigger electrical breakdown at sensitive junctures. In light of these challenges, we embarked on a series of experiments to understand electrical breakdown phenomena under diverse vacuum scenarios. These experiments, supplemented with finite element method (FEM) analysis, paved the way for the derivation of empirical formula. These formulas intend to guide the design of HTS magnets, ensuring their electrical insulation remains robust across a range of vacuum conditions.

Published
2024
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17. Investigation on nonuniform current density and shape deformation affecting the magnetic field performance of a saddle-shaped no-insulation HTS cosine–theta dipole magnet

Author

Kim, Geonyoung, primary, Park, Jeonghwan, additional, Bang, Jeseok, additional, Hahn, Garam, additional, Park, Seong Hyeon, additional, Im, Chaemin, additional, Park, Hyunsoo, additional, Kim, Jaemin, additional, Choi, Seyong, additional, Kang, Hyoungku, additional, Hahn, Seungyong, additional, and Lee, Sangjin, additional

Published
2023
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22. Experimental Study for Modified Lumped-Circuit Model to Analyze Saddle-Shaped No-Insulation HTS Coil Operated in Overcurrent Situation

Author

Kim, Geonyoung, primary, Jung, Wonju, additional, Koo, Jaheum, additional, Park, Jeonghwan, additional, Park, Hyunsoo, additional, Cha, JuKyung, additional, Lee, Jung Tae, additional, Jang, Wonseok, additional, Park, Seong Hyeon, additional, Yan, Yufan, additional, Kim, Jaemin, additional, Bang, Jeseok, additional, Hahn, Garam, additional, Choi, Seyong, additional, Kang, Hyoungku, additional, Hahn, Seungyong, additional, and Lee, Sangjin, additional

Published
2023
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23. Distributed-Circuit Method for Replication of Fast-Ramping of Saddle-Shaped REBCO Dipole Magnet Wound With Two-Tape Bundled Conductor

Author

Kim, Geonyoung, primary, Park, Hyunsoo, additional, Im, Chaemin, additional, Park, Jeonghwan, additional, Koo, Jaheum, additional, Jung, Wonju, additional, Lee, Jung Tae, additional, Jang, Wonseok, additional, Cha, JuKyung, additional, Yan, Yufan, additional, Kim, Jaemin, additional, Bang, Jeseok, additional, Hahn, Garam, additional, Choi, Seyong, additional, Kang, Hyoungku, additional, and Hahn, Seungyong, additional

Published
2023
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24. Degradation Characteristics of REBCO Tapes according to Electrical Breakdown

Author

Afif, Bimaridi, primary, Oh, Seunghee, additional, Jeong, Minkyung, additional, Park, Jinhyung, additional, Shin, Woocheol, additional, Jo, Uhyeon, additional, Handito, Ragil, additional, Park, Jeonghwan, additional, Kim, Geonyoung, additional, Hahn, Garam, additional, Choi, Seyong, additional, Hahn, Seungyong, additional, and Kang, Hyoungku, additional

Published
2023
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