Multichannel Microwave Interferometer for Simultaneous Measurement of Electron Density and its Fluctuation on HL-2A Tokamak

Shi, P.W.; Shi, Z.B.; Chen, Wei; Zhong, Weizhi; Yang, Z.C.; Jiang, M.; Boyu, Zhang; Li, Yonggao; Yu, Liming; Liu, Zetian; Ding, X.T.

doi:10.1088/1009-0630/18/7/02

Cited by 23 publications

(19 citation statements)

References 22 publications

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“…The phenomenon is perfectly reproducible. Mode features, including its frequency, mode-number and propagation direction, can be observed by ECEI, soft X-ray and microwave interference signals, respectively [14]. vector and L is the distance between two poloidal ECEI signals.…”

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confidence: 99%

Alfvénic ion temperature gradient activities in a weak magnetic shear plasma

Chen

et al. 2016

EPL

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We report the first experimental evidence of Alfvénic ion temperature gradient (AITG) modes in HL-2A Ohmic plasmas. A group of oscillations with f = 15 − 40 kHz and n = 3 − 6 is detected by various diagnostics in high-density Ohmic regimes. They appear in the plasmas with peaked density profiles and weak magnetic shear, which indicates that corresponding instabilities are excited by pressure gradients. The time trace of the fluctuation spectrogram can be either a frequency staircase, with different modes excited at different times or multiple modes may simultaneously coexist. Theoretical analyses by the extended generalized fishbone-like dispersion relation (GFLDR-E) reveal that mode frequencies scale with ion diamagnetic drift frequency and ηi, and they lie in KBM-AITG-BAE frequency ranges. AITG modes are most unstable when the magnetic shear is small in low pressure gradient regions. Numerical solutions of the AITG/KBM equation also illuminate why AITG modes can be unstable for weak shear and low pressure gradients. It is worth emphasizing that these instabilities may be linked to the internal transport barrier (ITB) and H-mode pedestal physics for weak magnetic shear. Kinetic Alfvén and pressure gradient driven instabilities are very common in magnetized plasmas both in space and laboratory[1][2][3]. In present-day fusion and future burning plasmas, they are easily excited by energetic particles (EPs) and/or pressure gradients. They can not only cause the loss and redistribution of EPs but also affect plasma confinement and transport[4][5]. The physics associated with them is an intriguing but complex area of research. For weak magnetic shear (s = (r/q)(dq/dr) ∼ 0) and low pressure gradients (α = −R 0 q 2 dβ/dr < 1; with β the ratio of kinetic to magnetic pressures.), the stability and effect of them, such as Alfvénic ion temperature gradient (AITG) mode[6][7]/kinetic ballooning mode (KBM)[8], have not been hitherto unrecognized. At weak magnetic shear, the first pressure gradient threshold becomes very small or vanishes and the AITG/KBM spectrum is unstable in the very low pressure gradient region[9][10]. For equilibria with reverse shear where q min is off axis and α max near q min , there exists an unstable low-n global branch of AITG and trapped electron dynamics can further destabilize it[11].The AITG/KBM modes, on the one hand, can cause cross-field plasma transport that set an upper limit on the arXiv:1611.05538v1 [physics.plasm-ph]

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confidence: 99%

Alfvénic ion temperature gradient activities in a weak magnetic shear plasma

Chen

et al. 2016

EPL

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“…Thereby, to estimate the particle flux, the radial profile is divided into edge part and core part as below

where

is the innermost radius that the reflectometer covers. As the density profile and its temporal evolution at core region (i.e., the region where

) is unknown, a quadratic-like core density profile is assumed according to the interferometer diagnostic system [ 22 ].

where

is the electron density at radius

(

).…”

Section: Resultsmentioning

confidence: 99%

“…where r 1 is the innermost radius that the reflectometer covers. As the density profile and its temporal evolution at core region (i.e., the region where r < r 1 ) is unknown, a quadratic-like core density profile is assumed according to the interferometer diagnostic system [22].…”

Section: Edge Transportmentioning

confidence: 99%

Experimental study of perturbative particle transport in the HL-2A tokamak

Zhang

Inagaki

Shi

et al. 2020

Heliyon

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Perturbative particle transport experiment has been performed in the HL-2A tokamak by using supersonic molecular beam injection (SMBI) as an external particle source. The spatiotemporal evolution of edge density perturbation is traced and the particle source and the flux-gradient relation are obtained experimentally. The flux-gradient relation is found to be far from the diffusive model and three different transport processes are revealed, including pinch-dominant process, diffusion-pinch process and intermittent decays.

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“…The layout of the microwave diagnostic systems is shown in figure 1. Three microwave interferometer systems are developed to measure the plasma line-averaged density and density fluctuations in the main plasma and divertor regions [22,23]. The multi-channel ECE and ECEI are developed to measure the electron temperature profiles and fluctuations [24][25][26][27][28][29][30].…”

Section: Overview Of Microwave Diagnostics On Hl-2amentioning

confidence: 99%

“…Three microwave interferometer systems have been developed to measure the plasma line-averaged density and the density fluctuations [22,23]. As shown in figure 1, two divertor interferometers are installed in the inner and outer divertor legs, respectively.…”

Section: Microwave Interferometersmentioning

confidence: 99%

Progress of microwave diagnostics development on the HL-2A tokamak

Shi

Zhong

Jiang

2018

Plasma Sci. Technol.

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Sets of powerful microwave diagnostic systems have been developed on the HL-2A tokamak, including 18 subsystems with high spatial and temporal resolutions. These systems have been applied in the HL-2A tokamak experiments to investigate the core plasma transport, turbulence, MHD, energetic particle physics and so on. In this paper, the microwave diagnostics and their applications are reviewed. Some new technologies, including GHz sampling digital correlation electron cyclotron emission (DCECE), multi-channel correlation reflectometers, and solid state terahertz interferometers, are also presented in the paper.

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Multichannel Microwave Interferometer for Simultaneous Measurement of Electron Density and its Fluctuation on HL-2A Tokamak

Cited by 23 publications

References 22 publications

Alfvénic ion temperature gradient activities in a weak magnetic shear plasma

Alfvénic ion temperature gradient activities in a weak magnetic shear plasma

Experimental study of perturbative particle transport in the HL-2A tokamak

Progress of microwave diagnostics development on the HL-2A tokamak

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