Instrumentation for a multichord motional Stark effect diagnostic in KSTAR

Chung, Jae-Hoon; Ko, Jinseok; Bock, de Mfm Maarten; Jaspers, Rje Roger

doi:10.1063/1.4891161

Cited by 25 publications

(13 citation statements)

References 6 publications

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“…It measures the emission of high velocity neutral deuterium particles injected by one of KSTAR's neutral heating beams. A detailed report of the setup, including a description of the invessel calibration and correction of the Faraday rotation, can be found at [4,6,7]. A brief overview of the setup will be given for completeness.…”

Section: Methodsmentioning

confidence: 99%

Evolution of the central safety factor during stabilized sawtooth instabilities at KSTAR

Messmer

Chung

et al. 2017

Nucl. Fusion

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Section: Methodsmentioning

confidence: 99%

Evolution of the central safety factor during stabilized sawtooth instabilities at KSTAR

Messmer

Chung

et al. 2017

Nucl. Fusion

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“…A Two-Colour Interferometer (TCI) with the CO 2 laser and Diodepumped-solid-state (DPSS) laser 64 and Electron Cyclotron Emission (ECE) measurements are used to determine the electron density and the temperature complementary to the TS measurements. The Motional Stark effect (MSE) diagnostic 65 is employed to extract the core current density pro le for the kinetic equilibrium construction. The properties of fast ions are diagnosed through the fast ion loss detector (FILD) 66 and the fast-ion D α (FIDA) 67…”

Section: Diagnosticsmentioning

confidence: 99%

A new regime that “FIRE”s fusion plasmas for long sustained and high performance reactor conditions

Han

Park

et al. 2021

Preprint

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We report a discovery of a fusion plasma regime suitable for commercial fusion reactor where the ion temperature was sustained above 100 million degree about 20 s for the first time. Nuclear fusion as a promising technology for replacing carbon-dependent energy sources has currently many issues to be resolved to enable its large-scale use as a sustainable energy source. State-of-the-art fusion reactors cannot yet achieve the high levels of fusion performance, high temperature, and absence of instabilities required for steady-state operation for a long period of time on the order of hundreds of seconds. This is a pressing challenge within the field, as the development of methods that would enable such capabilities is essential for the successful construction of commercial fusion reactor. Here, a new plasma confinement regime called fast ion roled enhancement (FIRE) mode is presented. This mode is realized at Korea Superconducting Tokamak Advanced Research (KSTAR) and subsequently characterized to show that it meets most of the requirements for fusion reactor commercialization. Through a comparison to other well-known plasma confinement regimes, the favourable properties of FIRE mode are further elucidated and concluded that the novelty lies in the high fraction of fast ions, which acts to stabilize turbulence and achieve steady-state operation for up to 20 s by self-organization. We propose this mode as a promising path towards commercial fusion reactors.

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“…plasma density and temperature profiles) in tokamak plasmas is well established and will not be discussed in this paper. There are two principal methods for measurement of the current density (or equivalently, poloidal field) in tokamak plasmas and both methods are technically complex and many factors can limit the required accuracy for the stability analysis: polarimetric measurement based on Faraday rotation [13][14][15] and spectroscopy based on the motional Stark effect (MSE) [16][17][18][19][20][21]. Since the required accuracy level varies for different instabilities under study, it is important to be aware of limitations of these methods which are critical for the model validation process.…”

Section: Measurement Of the Current Density Profile In Tokamak Plasmasmentioning

confidence: 99%

“…The spectroscopic method based on the Motional Stark Effect (MSE) [16][17][18][19][20][21] and Zeeman splitting [22] measures polarization angle of the MSE or Zeeman splitting and the resultant pitch angle measured depends on system geometry from equilibrium reconstruction. The nature of the MSE spectroscopy is the local measurement of the magnetic field line pitch angle by measuring the polarization of the emission of the injected neutral beam (which is usually the neutral beam used for heating the plasma) with known energy as illustrated in Figure 3.…”

Section: Measurement Of the Current Density Profile In Tokamak Plasmasmentioning

confidence: 99%

Newly uncovered physics of MHD instabilities using 2-D electron cyclotron emission imaging system in toroidal plasmas

Park

2019

Advances in Physics: X

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Validation of physics models using the newly uncovered physics with a 2-D electron cyclotron emission imaging (ECEi) system for magnetic fusion plasmas has either enhanced the confidence or substantially improved the modeling capability. The discarded "full reconnection model" in sawtooth instability is vindicated and established that symmetry and magnetic shear of the 1/1 kink mode are critical parameters in sawtooth instability. For the 2/ 1 instability, it is demonstrated that the 2-D data can determine critical physics parameters with a high confidence and the measured anisotropic distribution of the turbulence and its flow in presence of the 2/1 island is validated by the modelled potential and gyro-kinetic calculation. The validation process of the measured reversed-shear Alfvéneigenmode (RSAE) structures has improved deficiencies of prior models. The 2-D images of internal structure of the ELMs and turbulence induced by the resonant magnetic perturbation (RMP) have provided an opportunity to establish firm physics basis of the ELM instability and role of RMPs. The importance of symmetry in determining the reconnection time scale and role of magnetic shear of the 1/1 kink mode in sawtooth instability may be relevant to the underlying physics of the violent kink instability of the filament ropes in a solar flare.

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Instrumentation for a multichord motional Stark effect diagnostic in KSTAR

Cited by 25 publications

References 6 publications

Evolution of the central safety factor during stabilized sawtooth instabilities at KSTAR

Evolution of the central safety factor during stabilized sawtooth instabilities at KSTAR

A new regime that “FIRE”s fusion plasmas for long sustained and high performance reactor conditions

Newly uncovered physics of MHD instabilities using 2-D electron cyclotron emission imaging system in toroidal plasmas

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