디지털 트윈 기반의 핵융합에너지 시설 운용 시스템 개발

기재석(Ki, Jae-Seok),권재민(Kwon, Jae-Min),최호생(Chaoi, Ho-Saeng) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.6

이 논문에서는 핵융합 연구 장치인 KSTAR의 실험에 가상현실과 디지털트윈 기술을 적용한 Virtual KSTAR 개발을 소개하고자 한다. Virtual KSTAR 개발을 통해 KSTAR 실험 성과 향상에 기여 가능성을 살펴보고, 디지털트윈 기술을 통해 핵융합 에너지 개발이 마주한 과학 기술적 도전의 극복 가능성을 고찰해 보고자 한다. In this paper, we would like to introduce the development of Virtual KSTAR by applying digital twin technology to visualize the experiment and simulation of the KSTAR. Through the study on the development of Virtual KSTAR, we examine the possibility of contributing to the improvement of KSTAR experiment and future potential of V-KSTAR will be examined, and consider the possibility of overcoming the scientific and technological challenges faced by fusion energy development through digital twin technology.

미래 청정에너지원 KSTAR의 냉각수설비

이제묘(J. M. Lee),김영진(Y. J. Kim),박동성(D. S. Park),임동석(D. S. Lim) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6

Because of insufficiency of energy resources and pollution of environment, it is necessary to develop alternative energy sources. Nuclear fission energy is used widely for source of electric power but being restricted due to radioactivity problem. Nuclear fusion is highlighted as the new generation of nuclear energy and researched worldwide because of low risk of radiation effect. The representatives of fusion research is China's EAST, KSTAR of Korea and ITER of world. Korea Superconducting Tokamak Advanced Research(KSTAR) project is on progress for the completion in August, 2007. In this study, the research of utility system for KSTAR be carried out. The utility system of KSTAR is consist of water cooling & heating system, N₂ gas system, DㆍI water system, service water system and instrument air & auto control system. The progress of KSTAR utility system is under commissioning state after construction completion. The optimal operation scenario will be verified during commissioning and adopted to the KSTAR operation.

무한에너지원 KSTAR의 냉각수설비

이제묘(J. M. Lee),김영진(Y. J. Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

Because of insufficiency of energy resources and pollution of environment, it is necessary to develop alternative energy sources. Nuclear fission energy is used widely for source of electric power but being restricted due to radioactivity problem. Nuclear fusion is highlighted as the new generation of nuclear energy and researched worldwide because of low risk of radiation effect. The representatives of fusion research is China’s EAST, KSTAR of Korea and ITER of world. Korea Superconducting Tokamak Advanced Research(KSTAR) project is on progress for the completion in August, 2007. In this study, the research of utility system for KSTAR be carried out. The utility system of KSTAR is consist of water cooling & heating system, N₂ gas system, DㆍI water system, service water system and instrument air & auto control system. The progress of KSTAR utility system is under commissioning state after construction completion. The optimal operation scenario will be verified during commissioning and adopted to the KSTAR operation.

Overview of recent progress in 3D field physics in KSTAR

Park Gunyoung,In Yongkyoon,Park Jong-Kyu,Ko Won-Ha,Lee Jaehyun,Kim Minwoo,Shin Giwook,Hahn Sang-Hee,Kim SangKyeun,Yang Seong Moo,Hu Qiming,Rhee Tongnyeol,Choi Minjun J.,Kim Kimin,Lee Hyung-Ho,Jeon You 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.8

Various 3D field physics challenges of magnetically confined plasmas arise when the driving source comes from either externally applied non-axisymmetric 3D magnetic perturbations or plasma instabilities inside the plasma. Recently, several key outstanding topics of 3D field physics have been extensively studied in the Korean Superconducting Tokamak Advanced Research (KSTAR), such as edge-localized-mode (ELM) control by resonant magnetic perturbation (RMP), error field (EF) control, 3D field effects on rotation and transport, and RMP-induced alteration of divertor heat flux and detachment. KSTAR has a few physically unique features (i.e., high rotation and long-pulse plasmas with a low intrinsic EF) and machine/diagnostic capabilities (i.e., 3-row in-vessel control coil and state-of-the-art 2D/3D imaging diagnostics), which have been taken advantage of until now to address critical 3D field physics issues relevant to ITER and K-DEMO. Among many remarkable achievements are the robust access to and control of n = 1 RMP ELM suppression, along with a development of its physics basis tools, parameter expansion, optimization, and long-pulse control techniques. Nonetheless, a series of unresolved 3D physics themes, as well as limited coverage of 3D field operating regimes, have also been identified as future works for the 3D field research in KSTAR. In this paper, we provide an overview about the recent progress of KSTAR 3D field physics and present future plans of KSTAR 3D research toward a future fusion reactor.

An assessment of axial pre-compression for the KSTAR central solenoid

Ahn, H.J.,Kim, H.T.,Kim, Y.O.,Chu, Y.,Park, H.K.,Park, K.R.,Oh, Y.K.,Kim, Y.S.,Han, D.W.,Kim, Y.H. Elsevier 2017 Fusion engineering and design Vol.124 No.-

<P><B>Abstract</B></P> <P>The central solenoid (CS) of the KSTAR consists of four pairs of superconducting coils compressed axially by preloading structures. The axial pre-compression is needed to suppress the maximum attractive or repulsive force of the coils based on reference operation scenarios. All CS coils were assembled with eight sets of preloading and supporting structures under precise dimensional control. Only shells of preloading structures were heated to make 6mm gap between the preloading structure and coil assembly. The gap was, then, filled up by wedge movement so that axial pre-compression be applied after thermal contraction of shells. However measured pre-compression is about 55% of the design value. A detailed investigation has been carried out to find reasons for the preloading reduction by comparing strain measurement and structural analysis results. The minimum residual compression is estimated as 6.5MN. It is expected to have no serious problem during large plasma current H-mode discharge with consideration of the anti-slip design. A structural analysis model of KSTAR CS magnet has been developed based on the measured strains during operations and will give a guide line for future high performance and long pulse operations of KSTAR.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A detailed investigation has been carried out to find reasons for the preloading reduction for KSTAR CS by comparing strain measurement and structural analysis results. </LI> <LI> A structural analysis model of KSTAR CS magnet has been developed based on the measured strains during operations. </LI> <LI> It is expected to have no serious problem during large plasma current H-mode discharge in future with consideration of the anti-slip design of each component. </LI> </UL> </P>

Effective diagnostic DAQ systems to reduce unnecessary data in KSTAR

Lee, T.,Lee, W.,Hong, J.,Park, K. North-Holland 2016 Fusion engineering and design Vol.112 No.-

The plasma status of Korea Superconducting Tokamak Advanced Research (KSTAR) is measured by various diagnostics systems. The measured data size has been increasing every year due to increasing plasma pulse lengths, higher diagnostics operating frequencies, the additions of new diagnostic systems, and an increasing number of diagnostics channels. At times, when plasma shots do not successfully perform during the intended target time, the diagnostics systems continue to record these unusable data, contributing to increasing data size. In addition, the analysis time was affected, as these data need to be separated from the relevant data set. To overcome this problem, KSTAR's Standard Framework (SFW), Real Time Monitoring (RTMON), and Pulse Automation and Scheduling System (PASS) were upgraded to monitor the plasma status in real_time. When the plasma current is less than 200kA, RTMON sends the plasma status information every second to the SFW via EPICS Channel Access. With the real-time information on plasma status, some of the KSTAR diagnostic systems stop the acquisition process of unnecessary data. This paper describes a method for reducing the storage of unnecessary data and its results in the KSTAR 7th campaign.

Neutron emission in neutral beam heated KSTAR plasmas and its application to neutron radiography

KSTAR team,Kwak, J.G.,Kim, H.S.,Cheon, M.S.,Oh, S.T.,Lee, Y.S.,Terzolo, L. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

The main mission of Korea Superconducting Tokamak Advanced Research (KSTAR) program is exploring the physics and technologies of high performance steady state Tokamak operation that are essential for ITER and fusion reactor. Since the successful first operation in 2008, the plasma performance is enhanced and duration of H-mode is extended to around 50s which corresponds to a few times of current diffusion time and surpassing the current conventional Tokamak operation. In addition to long-pulse operation, the operational boundary of the H-mode discharge is further extended over MHD no-wall limit(β<SUB>N</SUB>~4) transiently and higher stored energy region is obtained by increased total heating power (~6MW) and plasma current (I<SUB>p</SUB> up to 1MA for ~10s). Heating system consists of various mixtures (NB, ECH, LHCD, ICRF) but the major horse heating resource is the neutral beam(NB) of 100keV with 4.5MW and most of experiments are conducted with NB. So there is a lot of production of fast neutrons coming from via D(d,n)<SUP>3</SUP>He reaction and it is found that most of neutrons are coming from deuterium beam plasma interaction. Nominal neutron yield and the area of beam port is about 10<SUP>13</SUP>-10<SUP>14</SUP>/s and 1m<SUP>2</SUP> at the closest access position of the sample respectively and neutron emission could be modulated for application to the neutron radiography by varying NB power. This work reports on the results of quantitative analysis of neutron emission measurements and results are discussed in terms of beam-plasma interaction and plasma confinement. It also includes the feasibility study of neutron radiography using KSTAR.

Development of pellet injection system for KSTAR

Park, Soo-Hwan,Kim, Hong-Tack,Vinyar, Igor,Lee, Juhyoung,Lukin, Alexander,Kim, Kyungmin,Park, Hyun-Ki,Ahn, Hee-Jae,Lee, Jonghwa Elsevier 2017 Fusion engineering and design Vol.123 No.-

<P><B>Abstract</B></P> <P>KSTAR (Korea Superconducting Tokamak Advanced Research) has used a gas puffing system as a main fueling method since 2008. Up to date total fueling efficiency of the gas puff is less than 30%. A pellet injection is a more effective technique to control a plasma density than the gas puffing system and a supersonic molecular beam injection. Therefore, we have developed the pellet injection system for KSTAR. The pellet injection system for KSTAR consists of a pellet injector which injects pellets of a deuterium (diameter of 2mm, length of 1.5–2mm) at a velocity above 200m/s with an injection frequency of 1–20Hz, a 2-stage differential pumping system, a guide tube, a control system and so on. It is planned to inject pellets through a high field side and increase the plasma performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of the pellet injection system for KSTAR is carried out successfully. </LI> <LI> The performance of pellet injector meets requirements and our expectation during commissioning. </LI> <LI> Modification of guide tube, optimization of cooling facility and so on will be done. </LI> </UL> </P>

On confinement characteristics of the newly developed sawtooth-free plasmas in KSTAR tokamak

Byun, C.s.,Na, Y.S.,Kim, H.S.,Kim, S.H. Elsevier 2014 Current Applied Physics Vol.14 No.1

Development of advanced scenarios, an important experimental goal of the Korea superconducting tokamak advanced research (KSTAR) project, has just begun. The safety factor (q) profile is a key to achieve these advanced scenarios. Particularly the hybrid scenario, one of the advanced scenarios, can be established generally with low magnetic shear (s) at the center with central q-value above unity so to avoid sawtooth instability. This q-profile was successfully produced using early divertor formation during a plasma current ramp-up phase in KSTAR. Auxiliary heating was also employed during the current ramp-up phase to delay the inductive current diffusion to the center of the plasma. In addition to the early divertor formation method, the target q-profile was attempted to be achieved by modifying the plasma current waveform using the so-called, 'current-overshoot' method and the timing of L-mode to H-mode transition. In this work, the confinement characteristics of these sawtooth-free regimes are investigated. The global energy confinement time is calculated and compared with that of conventional H-modes in KSTAR. The confinement enhancement factor reveals that the newly developed discharges are not improved over H-modes contrary to results of other tokamaks. To investigate the reason, transport modeling is performed self-consistently with an integrated simulation package incorporating plasma equilibrium, transport, and heating and current drive. The current ramp-up phase is simulated and impact of early divertor formation, current-overshoot, and early L-H transition on the target q-profile and s/q profile is addressed. The s/q profile is found to be not improved in these discharges compared with hybrid scenarios reported in other tokamaks. Based on these results, future experimental directions are addressed to access the hybrid regimes in KSTAR.

On confinement characteristics of the newly developed sawtooth-free plasmas in KSTAR tokamak

변철식,나용수,H.-S. KIM,S.H.Kim 한국물리학회 2014 Current Applied Physics Vol.14 No.1

Development of advanced scenarios, an important experimental goal of the Korea superconducting tokamak advanced research (KSTAR) project, has just begun. The safety factor (q) profile is a key to achieve these advanced scenarios. Particularly the hybrid scenario, one of the advanced scenarios, can be established generally with low magnetic shear (s) at the center with central q-value above unity so to avoid sawtooth instability. This q-profile was successfully produced using early divertor formation during a plasma current ramp-up phase in KSTAR. Auxiliary heating was also employed during the current ramp-up phase to delay the inductive current diffusion to the center of the plasma. In addition to the early divertor formation method, the target q-profile was attempted to be achieved by modifying the plasma current waveform using the so-called, ‘current-overshoot’ method and the timing of L-mode to H-mode transition. In this work, the confinement characteristics of these sawtooth-free regimes are investigated. The global energy confinement time is calculated and compared with that of conventional H-modes in KSTAR. The confinement enhancement factor reveals that the newly developed discharges are not improved over H-modes contrary to results of other tokamaks. To investigate the reason, transport modeling is performed self-consistently with an integrated simulation package incorporating plasma equilibrium, transport, and heating and current drive. The current ramp-up phase is simulated and impact of early divertor formation, current-overshoot, and early LeH transition on the target qprofile and s/q profile is addressed. The s/q profile is found to be not improved in these discharges compared with hybrid scenarios reported in other tokamaks. Based on these results, future experimental directions are addressed to access the hybrid regimes in KSTAR.