Fast ion D-alpha measurements using a bandpass-filtered system on EAST

Zhang, J.; Huang, J.; Chang, Jiafeng; Wu, Cong-Feng; Heidbrink, W. W.; Salewski, M.; Madsen, B.; Zhu, Y. B.; Hellermann, M. G. von; Gao, Wei; Xu, Z.; Wan, Baonian

doi:10.1063/1.5038828

Cited by 8 publications

(4 citation statements)

References 14 publications

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“…Previous studies have shown that reconstructing the velocity distribution function from a diagnostic system with incomplete coverage of velocity space is a challenging task [7,11,[14][15][16]. Specifically at the EAST tokamak, the two-view FIDA diagnostic [17,18] is sensitive to fast ions in substantial regions of velocity space, but leave other regions covered by only one view [19]. To nevertheless enable reliable reconstructions of the fast-ion distribution from sparse datasets, a palette of prior information has been developed [14,15,20].…”

Section: Introductionmentioning

confidence: 99%

Fast-ion velocity-space tomography using slowing-down regularization in EAST plasmas with co- and counter-current neutral beam injection

Madsen¹,

Huang²,

Salewski³

et al. 2020

Plasma Phys. Control. Fusion

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We demonstrate 2D reconstructions of the fast-ion velocity distribution from two-view fast-ion D-alpha (FIDA) measurements at the EAST tokamak. By expressing the distribution in a basis relying on the fast-ion slowing-down process in fusion plasmas, the smoothness and velocity-space resolution of reconstructions are improved. We reconstruct distributions of fast ions born from simultaneous co-and counter-current neutral beam injection and detect the expected distinct change in fast-ion birth pitch when comparing discharges utilizing different neutral beam injectors. For purely co-current injection, we find a good agreement between TRANSP-predicted and reconstructed fast-ion densities, pressures and current densities for energies above 20 keV. We furthermore illustrate the improvement of the reconstructed high-energy range (> 40 keV) of the distribution by combining FIDA with neutron emission spectroscopy (NES) measurements with the compact single-plate EJ301 scintillator.

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Section: Introductionmentioning

confidence: 99%

Fast-ion velocity-space tomography using slowing-down regularization in EAST plasmas with co- and counter-current neutral beam injection

Madsen¹,

Huang²,

Salewski³

et al. 2020

Plasma Phys. Control. Fusion

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“…Therefore, understanding fast-ion behaviour and related physical issues is a critical aspect to achieve the EAST scientific objectives. Accordingly, several complementary fast-ion measurements [13,14] have been developed and validated on EAST, e.g. fast-ion D-alpha (FIDA), fast-ion loss detectors (FILDs), neutral particle analysers (NPA), neutron flux monitor and TOFED neutron spectrometers.…”

Section: Introductionmentioning

confidence: 99%

Improved high-performance fully non-inductive discharge by optimizing the fast-ion confinement on EAST

et al. 2019

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The long-pulse high-performance fully non-inductive plasma is one of the major scientific objectives on EAST using the ITER-like tungsten upper divertor. Understanding and optimizing the fast-ion behaviors is the critical issue to extend the performance on EAST. Recently, using both NBI (neutral beam injection) and RF (low hybrid, electron cyclotron and ion cyclotron) heating, fully non-inductive high-β P scenarios with extension of fusion performance at high density and low rotation have been achieved with β P up to 2.5, β N up to 2.0 and H 98y2 >1.1, with the bootstrap current fraction (f BS) up to 50%. For previous longpulse H-mode plasma at medium density, compared with RF-only discharges, when NBI is added into RF plasma β p is increased from 1.2 to 2.0. In fact, f BS for both discharges are nearly the same ~22%. The analysis shows that the increase in β p is mostly due to fast ions which do not contribute significantly to the neoclassical bootstrap current. Thus, to obtain high performance plasmas with the improved bootstrap current fraction, key parameters (e.g. density, beam energy, etc.) are further optimized. Experimental results show that high density improves bootstrap fraction also by reducing fast-ion slowing down time and loss, as well as the lower beam energy mitigates fast-ion loss which is better for heating and CD performance. The extension of high performance fully non-inductive experiments on EAST at high density and zero/low NBI torque can offer unique contributions towards ITER and CFETR.

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“…They can also drive instabilities, which can act on specific parts of the fast-ion velocity-space distribution, causing anomalous fast-ion redistribution and loss [2] potentially resulting in damage to the components on the first wall. To obtain information about fast-ion velocity-space distribution function, fast-ion D-alpha (FIDA) measurements [3,4] are commonly used in tokamak and stellarator devices, such as DIII-D [5], LHD [6], NSTX [7], ASDEX Upgrade [8], TCV [9], MAST [10], experimental advanced superconducting tokamak (EAST) [11,12]. The principle of the FIDA diagnostic is that the neutralized fast ions, resulting from chargeexchange reactions, are in excited states and emit Balmeralpha radiation with a Doppler shift that is dependent on the fast-ion velocity.…”

Section: Introductionmentioning

confidence: 99%

Reconstructions of velocity distributions from fast-ion D-alpha (FIDA) measurements on EAST

Wan

Huang

et al. 2021

Plasma Sci. Technol.

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2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha (FIDA) measurements on experimental advanced superconducting tokamak (EAST). To make up for the sparse data and incomplete velocity-space coverage with the dual-view, we use nonnegativity and null-measurements as prior information to reconstruct the velocity distribution in experiments with co-and counter-current neutral beam injection. An improved reconstructed fast-ion distribution is achieved by combining the existing O-and B-port FIDA measurements with the proposed A-port FIDA view. To further improve the reliability of FIDA-based reconstructions on EAST, based on real multi-view FIDA measurements on EAST in the near future, various bases will be studied further.

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Fast ion D-alpha measurements using a bandpass-filtered system on EAST

Cited by 8 publications

References 14 publications

Fast-ion velocity-space tomography using slowing-down regularization in EAST plasmas with co- and counter-current neutral beam injection

Fast-ion velocity-space tomography using slowing-down regularization in EAST plasmas with co- and counter-current neutral beam injection

Improved high-performance fully non-inductive discharge by optimizing the fast-ion confinement on EAST

Reconstructions of velocity distributions from fast-ion D-alpha (FIDA) measurements on EAST

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