Overview of the electron cyclotron emission measurements on EAST

Liu, Yong; Zhao, Hailin; Zhou, Tianfu; Liu, Xiang; Zhang, Zhu; Han, Xiang; Schmuck, S.; Fessey, J.; Trimble, P.; Domier, Calvin; Luhmann, N. C.; Ti, Ang; Li, Erzhong; Ling, Bili; Hu, Liqun; Feng, Xi; Liu, Ahdi; Rowan, W. L.; Huang, He; Phillips, P. E.

doi:10.1016/j.fusengdes.2017.12.032

Cited by 26 publications

(13 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The density profile is measured by means of fast frequencysweeping reflectometry [20][21][22], for which the horizontal view is approximately 3 cm above the low-field side (LFS) on the midplane at port J. A 48-channel heterodyne radiometer (Xmode electron cyclotron emission (ECE)) is used to measure the electron temperature perturbation [23]. In addition, 11-channel polarimeter-interferometer (POINT) diagnostics [24] are used to measure the line-averaged densities.…”

Section: Methodsmentioning

confidence: 99%

Power threshold and confinement of the I-mode in the EAST tokamak

Liu

et al. 2020

Nucl. Fusion

View full text Add to dashboard Cite

Sixty-five discharges have been confirmed as I-mode discharges after searching the EAST database from 2016 to 2018, and some additional I-mode discharges were obtained in 2019. The I-mode regime features no edge localized modes (ELMs), high energy confinement, and a steep temperature pedestal, while particle confinement remains at L-mode levels. The I-mode regime has been obtained over a small parameter space (B T = 2.4 -2.7 T, I p = 0.4 -0.6 MA, q 95 = 4 -6) using a configuration with B × ▽B drift away from the active X-point. Most of the discharges in EAST are dominated by lower hybrid wave (LHW) heating. In addition, some are heated with both LHW and neutral beam injection (NBI) heating, and a few discharges are heated by NBI and electron cyclotron resonance heating (ECRH). Turbulence suppression in density perturbation has been defined as signaling the onset of the L-I transition. The power threshold of the I-mode is slightly larger than that of the 2008 ITPA scaling law of H-mode. The minimum L-I power threshold varies only weakly with B T , and the power range for the I-mode increases with increasing B T . The I-mode is superior to the L-mode in terms of energy confinement but is still slightly inferior to the H-mode under similar conditions, although the energy confinement time decreases more slowly with increasing heating power than it does in the typical H-mode case. NBI has some benefit for achieving higher confinement. The I-mode is very sensitive to the density near the edge. Under a constant high heating power, a small enhancement in the density will terminate the I-mode, sometimes leading to the I-H transition.

show abstract

Section: Methodsmentioning

confidence: 99%

Power threshold and confinement of the I-mode in the EAST tokamak

Liu

et al. 2020

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…Essential diagnostics help observe the behaviors of REs with a broad energy range in EAST. A multi-channel ECE diagnostic [27,28] can indicate the onset of the TQ by a rapid drop in the electron temperature and provides information on non-relativistic REs at energies below several tens of keV. CdTe and bismuth germinate (BGO) hard x-ray (HXR) detectors [29,30] help measure HXRs with energies in the ranges of 30-300 keV and 0.34-6.13 MeV emitted during RE collisions with impurities or the vessel wall.…”

Section: Methodsmentioning

confidence: 99%

Runaway electron generation and loss in EAST disruptions

et al. 2021

Self Cite

View full text Add to dashboard Cite

Runaway currents have been detected during unintended disruptions in the circular plasma with the limiter configuration in the Experimental Advanced Superconducting Tokamak (EAST). The runaway electron (RE) plateau can carry up to 80% of the pre-disruption plasma current. The highest runaway currents correspond to the lowest loop voltage, which is contrary to the observations made in most tokamaks. This anomalous behavior is attributed to the acceleration of the pre-existing wave resonant suprathermal electrons by lower hybrid waves during the disruption decay phase. Two distinct types of RE-related relaxation phenomena, distinguished on the basis of the amplitude of the magnetic fluctuations, have been found during the disruptions. Large-amplitude magnetohydrodynamic activity with indications of RE loss is observed during the RE plateau when the edge safety factor decreases to less than 3, and the external kink mode is discussed to resolve this anomaly. Burst-like relaxations with small-amplitude magnetic fluctuations and ∼0.6 kHz frequency are confirmed from the spikes in the hard x-ray array signals under a negative loop voltage. Measurement of the RE energy distribution suggests that the instability is driven by medium-energy REs.

show abstract

“…The ion temperature is detected using charge exchange recombination spectroscopy [28] and a tangential x-ray imaging crystal spectrometer [29]. The electron temperature is measured by Thomson scattering diagnosis [30] and electron cyclotron emission diagnosis [31]. The magnetic fluctuations were monitored by the Mirnov probe.…”

Section: Methodsmentioning

confidence: 99%

Dynamics between toroidal Alfvén eigenmode evolution and turbulence suppression under resonant magnetic perturbations on EAST

et al. 2021

Nucl. Fusion

View full text Add to dashboard Cite

Since Alfvén activity and turbulence are ubiquitous in magnetically confined plasma, it is important to understand the possible roles Alfvén activity have in the nonlinear evolution of turbulence. The designed experiments in low collisionality are dedicated to studying the dynamics between turbulence and toroidal Alfvén eigenmodes (TAEs), and assessing the multi-scale physics on the long-term scale behavior of fusion plasma. In TAEs (f ∼ 200 kHz, n = 1) mitigation experiments under resonant magnetic perturbations (RMP, n upper = 2 and n lower = 3), there is a long-term (∼500 ms) quasi-stationary state after RMP rapidly reduces the TAEs amplitude four times. Turbulence suppression (2.0 < kρ s < 3.8) and low-frequency zonal flow (LFZF) generation are observed in this period. Similar experiments show that energetic particles (EPs) may act as a mediator of the cross-scale interactions and are beneficial for turbulence suppression and LFZF generation. Besides the synchronous couplings of turbulence (2.0 < kρ s < 3.8) and TAEs, TAEs and LFZF are observed. The dynamics between turbulence and TAEs provides an idea for synchronous control of TAEs and turbulence, and the resulting EPs confinement improvement, T e increase, T i increase and plasma stored energy increase are favorable for plasma performance.

show abstract

Overview of the electron cyclotron emission measurements on EAST

Cited by 26 publications

References 10 publications

Power threshold and confinement of the I-mode in the EAST tokamak

Power threshold and confinement of the I-mode in the EAST tokamak

Runaway electron generation and loss in EAST disruptions

Dynamics between toroidal Alfvén eigenmode evolution and turbulence suppression under resonant magnetic perturbations on EAST

Contact Info

Product

Resources

About