Article
Nuclear Science & Technology
Youngho Lee, Jinseok Ko, Yong-Su Na
Summary: A newly developed systematic approach has been introduced to evaluate the impact of multi-ion-source neutral beam injection on the motional Stark effect (MSE) diagnostic in KSTAR. Through its application to a group of plasma discharges, this method has demonstrated its capability to guide researchers on neutral beam operation and high-quality MSE measurements.
FUSION ENGINEERING AND DESIGN
(2021)
Article
Instruments & Instrumentation
D. M. Liu, X. H. Yang, J. Fu, L. C. Liu, B. Lyu
Summary: The plasma current density profile is crucial for the development of a high poloidal beta scenario on a tokamak. A real-time signal processing system has been developed to control the plasma current density profile, with successful validation of its effectiveness and fast response capability.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Physics, Fluids & Plasmas
Yichao LI, Jia Fu, Yao Huang, Jinping Qian, Ang Ti, Cheonho Bae, Shengyu Fu, Jiankang LI, Yongqi Gu, Zhengping Luo, Jinseok Ko, Yongqing Wei, Dongmei Liu, Bingjia Xiao, Bo Lyu, Xianzu Gong, Baonian Wan
Summary: A new multi-channel motional Stark effect (MSE) diagnostic system has been developed on the EAST tokamak for observing a tangential neutral beam. The system utilizes a telecentric imaging lens and a square fiber head with 23 fiber bundles. The MSE system currently has 10 channels, but will be extended to 23 channels in the future, providing measurements with high temporal and spatial resolutions.
PLASMA SCIENCE & TECHNOLOGY
(2023)
Article
Optics
J. Rosato
Summary: The shape of spectral lines in strongly magnetized plasmas is theoretically investigated in this paper, which belongs to the field of astrophysical research. It is found that the broadening of lines observed on white dwarf spectra is mainly dominated by the motional Stark effect caused by the Lorentz electric field v ($) over right arrow x B ($) over right arrow. The modification of motional Stark broadening is demonstrated through dedicated line shape calculations based on a stochastic model for the atomic velocity. A universal line shape formula applicable to any isolated atomic line is proposed for implementation in line shape codes.
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
(2023)
Article
Instruments & Instrumentation
B. S. Victor, S. L. Allen, C. T. Holcomb, C. Samuell, A. Thorman
Summary: A new diagnostic technique has been developed that integrates a spectrometer and an image-intensified camera into the traditional motional Stark effect system on DIII-D, allowing for the measurement of polarization dependent phase shift likely caused by a plasma facing mirror. The technique can spectrally resolve the Stokes parameters and detect a change in polarization angle across the MSE spectrum of approximately 8 degrees.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Instruments & Instrumentation
Jinseok Ko, Steve Scott, Fred Levinton, Matthew Galante, Steve Sabbagh, Sang-hee Hahn, YoungMu Jeon
Summary: A new MSE diagnostic technique has been successfully developed and applied to address the issues of polarized background light in MSE measurements in the KSTAR device. A new calibration method has been devised to avoid potential contamination in conventional calibration processes, and has been validated through plasma jog experiments.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Instruments & Instrumentation
M. A. Makowski, B. S. Victor
Summary: The FFT based method significantly improves the frequency response of the MSE system, providing more accurate signal analysis compared to traditional analog lock-in methods. It operates by using fits to rigorous analytic expressions for the FFT spectral components of the MSE signal.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Instruments & Instrumentation
M. Sanders, K. Ida, M. Yoshinuma, C. Suzuki, Y. Yoshimura, R. Seki, M. Emoto, M. Yoshida, T. Kobayashi
Summary: The analysis method of the Motional Stark Effect (MSE) diagnostic has been improved to measure rotational transform and current profiles in the Large Helical Device. This improvement allows for higher accuracy in the measurements, especially near the magnetic axis.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Instruments & Instrumentation
Jinseok Ko
Summary: The MSE diagnostic system at KSTAR suffers from possible systematic uncertainties in measurements due to overlap of the MSE spectra generated from three different ion sources. A Stokes-vector analysis combined with practical factors has been conducted to generate a quantitative guideline for operating the multiple-ion-source neutral beam heating system.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Nuclear Science & Technology
YoungHwa An, Boseong Kim, Haewon Shin, Yeonjung Kim, Changrae Seon, Inwoo Song, MunSeong Cheon
Summary: An I & C system has been developed to facilitate the stable monitoring of impurity species in plasmas, providing both machine protection and plasma control. The system includes automated data acquisition and remote control of VUV spectrometer systems, as well as the implementation of interlocks to protect the main vacuum and the VUV spectrometers.
FUSION ENGINEERING AND DESIGN
(2022)
Article
Instruments & Instrumentation
J. W. Yoo, J. Kim, M. W. Lee, J. Kang, W. H. Ko, S. G. Oh, J. Ko, J. H. Lee, Y. U. Nam, L. Jung, B. H. Park, S. W. Yoon
Summary: A fast-ion D alpha (FIDA) diagnostics system was installed on KSTAR for core and edge measurements, with effective prevention of signal saturation by the cold D alpha line from the plasma edge and good quantitative matching of indices. Additionally, FIDA radiance was found to be consistent with neutron rate and responses in core FIDA radiance were observed during the edge-localized mode cycle.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Nuclear Science & Technology
J. W. Yoo, J. Kim, M. K. Kim, S. H. Park, B. H. Park, Y. U. Nam, J. W. Kim, H. Wi, M. Lehnen, W. C. Kim
Summary: Fast visible cameras can provide detailed dynamics of fusion plasma, with images from different toroidal positions helping understand the 3D structure of the plasma phenomena. The FVC system installed in KSTAR investigates the assimilation process during plasma disruptions induced by Shattered Pellet Injections, requiring good toroidal coverage and high spatial and temporal resolution.
FUSION ENGINEERING AND DESIGN
(2022)
Article
Nuclear Science & Technology
Jong-ha Lee, Seung Ju Lee, Ha Jin Kim, Sang Hee Hahn, Ichihiro Yamada, H. Funaba
Summary: This paper presents a prototype real-time Thomson scattering system that successfully transferred electron temperature data to the KSTAR plasma control system. The system utilizes a 155-channel 5 GS/s digitizer and applies pulse fitting and Fast Fourier Transformation (FFT) method to remove noise from the signals. A neural-network analysis method is employed for plasma parameter calculation. The data transfer was achieved within 50 ms.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Chemistry, Multidisciplinary
Ryan P. Sullivan, John T. Morningstar, Eduardo Castellanos-Trejo, Mark E. Welker, Oana D. Jurchescu
Summary: Molecular electronic devices have the potential to miniaturize electronic circuits and introduce novel functionalities. Quantum effects play a crucial role in device properties, and understanding the mechanisms of charge transport is important. Our investigation revealed that efficient current rectification in molecular diodes can be achieved by enhancing the Stark effect and enabling a large number of molecules to participate in transport. These findings provide insights for the design and operation of molecular devices.
Article
Multidisciplinary Sciences
Kirill Vasilev, Benjamin Doppagne, Tomas Neuman, Anna Roslawska, Herve Bulou, Alex Boeglin, Fabrice Scheurer, Guillaume Schull
Summary: The authors demonstrate the internal Stark effect by observing spectral shifts in the fluorescence spectrum of a phthalocyanine molecule caused by electrostatic fields generated within the molecule itself. This phenomenon of tuning chromophores' optical properties using electrostatic fields is known as the internal Stark effect (ISE) and plays a crucial role in optimizing complex functions in living organisms. By sequentially removing central protons from a free-base phthalocyanine chromophore with a scanning tunneling microscope, the authors were able to measure the Stark shift in the emission energy caused by the charges confined within the chromophore.
NATURE COMMUNICATIONS
(2022)
