Measurements of the fast electron bremsstrahlung during lower hybrid current drive in the HL-2A tokamak

Zhang, Y. P.; Mazon, D.; Peysson, Y.; Malard, P.; Zhang, P. F.; Zhang, J.; Zou, X. L.; Zhou, J.; Xu, Huang; Bai, Xue; Yang, Jianhua; Yuan, Guoliang; Song, Xiao Yan; Li, X.; Zhong, W.L.; Ding, X.T.; Chen, W.; Li, Y. G.; Hoang, T.; Delpech, L.; Isobe, M.; Lü, B.; Liu, Yi; Shi, Z.B.; Yang, Qingwei; Xu, M.; Duan, X.R.; Liu, Y.

doi:10.1063/1.5110233

Cited by 11 publications

(4 citation statements)

References 39 publications

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“…It can be clearly seen that there is no RE beam during disruption with LBO. The measurement results from the HXR camera [19] show that almost all energetic electrons are lost under strong magnetic fluctuation before disruption. That is, the 'seed' electrons that would form the RE beam are 'killed' [20], which prevents or suppresses the generation of REs during disruption.…”

Section: Disruption Mitigation 231 Lbo For Disruption Mitigationmentioning

confidence: 99%

Progress of HL-2A experiments and HL-2M program

Duan¹,

Xu²,

Zhong³

et al. 2022

Nucl. Fusion

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Since the last IAEA Fusion Energy Conference in 2018, significant progress of the experimental program of HL-2A has been achieved on developing advanced plasma physics, edge localized mode (ELM) control physics and technology. Optimization of plasma confinement has been performed. In particular, high-N H-mode plasmas exhibiting an internal transport barrier have been obtained (normalized plasma pressure N reached up to 3). Injection of impurity improved the plasma confinement. ELM control using resonance magnetic perturbation (RMP) or impurity injection has been achieved in a wide parameter regime, including Types I and III. In addition, the impurity seeding with supersonic molecular beam injection (SMBI) or laser blow-off (LBO) techniques has been successfully applied to actively control the plasma confinement and instabilities, as well as the plasma disruption with the aid of disruption prediction. Disruption prediction algorithms based on deep learning are developed. A prediction accuracy of 96.8% can be reached by assembling convolutional neural network (CNN). Furthermore, transport resulted from a wide variety of phenomena such as energetic particles and magnetic islands have been investigated. In parallel with the HL-2A experiments, the HL-2M mega-ampere class tokamak was commissioned in 2020 with its first plasma. Key features and capabilities of HL-2M are briefly presented.

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Section: Disruption Mitigation 231 Lbo For Disruption Mitigationmentioning

confidence: 99%

Progress of HL-2A experiments and HL-2M program

Duan¹,

Xu²,

Zhong³

et al. 2022

Nucl. Fusion

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“…The lower-hybrid wave/current drive (LHW/LHCD) at 2. 45 GHz was deposited in the plasma core with the power of 0.3-0.5 MW [40]. Figure 1(a) shows the sight lines of two soft x-ray (SX) spectroscopies, the positions of the beam emission spectroscopy (BES), electron cyclotron emission (ECE) and charge exchange recombination spectroscopy (CXRS) in the poloidal cross section.…”

Section: Methodsmentioning

confidence: 99%

Coupling among neoclassical tearing modes, edge localized modes and Alfvén eigenmodes in HL-2A high β H-mode plasmas

Jiang¹,

Xu²,

Chen³

et al. 2022

Nucl. Fusion

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In this work, the coupling among several MHD modes across different spatial regions, including the neoclassical tearing mode (NTM) and two branches of Alfvén eigenmode (AE) in the core and the edge localized mode (ELM), has been investigated in the HL-2A high beta H-mode plasmas. The NTMs induce a saturated m/n=1/1 helical core (m and n are the poloidal and toroidal mode numbers, respectively) through the ”magnetic-flux pumping” effect. The ELM crash results in a rapid (< 1 ms) decrease of the NTM island width followed by a much slower recovery. The degree of the island-width drop is proportional to the normalized beta as well as the ELM size, and can be up to 60%. In addition, two branches of AEs, in the toroidal Alfvén eigenmode (TAE) and beta-induced Alfvén eigenmode (BAE) bands, become evident after the 2/1 NTM onset and their magnitudes are modulated by the 2/1 NTM rotation. Besides, the changes of the TAE and BAE amplitudes are closely related to the temporal evolution of the ELM crash event, implying the strong interaction between AEs and the ELM. It is found that the coupling among these MHD modes in the core region during the NTM phase regulates the edge transport, i.e., relaxation of the pressure profiles, mitigation of the peeling-ballooning instability, reduction of the radial electric field shear and enhancement of the turbulent transport in the pedestal region.

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“…Main plasma parameters of the HL-2A tokamak are listed as follows: major radius 𝑅 = 1.65 m, minor radius 𝑎 ≈ 0.4 m, plasma current 𝐼 p = 150-430 kA, central line-averaged electron density 𝑛 e = (0.8-6) × 10 19 m −3 , toroidal magnetic field 𝐵 T = 1.3-2.7 T, electron temperature 𝑇 e up to 5 keV, and ion temperature 𝑇 i up to 2.8 keV [7]. Since the physics related to energetic electrons in lower hybrid current drive (LHCD) plasma is an important issue in plasma physics [10], it is of interest to study the local HXR emission profiles on HL-2A when the LHCD system [19] is available.…”

Section: Application In the Hl-2a Experimental Campaign 41 Experimentsmentioning

confidence: 99%

“…Determination for the local HXR emission profile is crucial for energetic electron behavior analyses. The hard X-ray camera, which is arranged by focusing multichord layout, provides the line-integrated HXR emission profiles with a time resolution of 2 ∼ 16 ms [10]. In order to evaluate the spatial distribution of the HXR emissivity, i.e., the local HXR emission profile, a reconstruction 2021 JINST 16 P03034 procedure is necessary.…”

Section: Introductionmentioning

confidence: 99%

Application of the Abel-inversion method for the hard X-ray camera on the HL-2A tokamak

Zhang¹,

Zhang²,

Li³

et al. 2021

J. Inst.

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The hard X-ray camera on the HL-2A tokamak has been used to study the behavior of energetic electrons in fusion plasma. In order to get precise hard X-ray emissivity information from the camera, a new hard X-ray emission profile reconstruction procedure based on the Abel-inversion method has been developed in the present paper. According to the verification results, the accuracy of the Abel-inverted profile depends on the accuracy of the interpolation and fitting processes. However, the error of the Abel-inverted profile is acceptable for the hard X-ray camera in general. For its applications, the procedure has been used to calculate the experimental local hard X-ray emission profiles. The calculation results show that the hard X-ray emission profiles were peaked at the center of the plasma, indicating the main energy of the lower hybrid wave was deposited at the center producing more energetic electrons than elsewhere. In addition, the calculation results can also indicate the confinement quality for energetic electrons, which can also be supported by statistical analyses for the line-integrated HXR emission profiles. The present paper lays a good foundation for the application of the hard X-ray camera on the HL-2A tokamak.

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Measurements of the fast electron bremsstrahlung during lower hybrid current drive in the HL-2A tokamak

Cited by 11 publications

References 39 publications

Progress of HL-2A experiments and HL-2M program

Progress of HL-2A experiments and HL-2M program

Coupling among neoclassical tearing modes, edge localized modes and Alfvén eigenmodes in HL-2A high β H-mode plasmas

Application of the Abel-inversion method for the hard X-ray camera on the HL-2A tokamak

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