Xuru Duan's research while affiliated with Southwestern Institute of Physics and other places

Publications (89)

Article
The China Fusion Engineering Test Reactor (CFETR) is the next step in China's roadmap for magnetic confinement fusion development. It aims to bridge the gap between the ITER fusion experimental reactor and the demonstration fusion power reactor (DEMO). The CFETR will be operated in two phases. Phase I aims to achieve fusion power of 50–200 MW, Qpla...
Article
Mitigation of long-lived mode (LLM) by lower hybrid wave (LHW) is recently achieved on the HL-2A tokamak. The long-lived mode changes from a typical steady-state to a fishbone- like frequency-chirping characteristic, and its higher poloidal harmonics disappear when LHW is injected into toroidal plasma. It is found that density fluctuation declines...
Article
Full-text available
Fusion energy is a promising source of clean energy, which could solve energy shortages and environmental pollution. Research into controlled fusion energy has been ongoing for over half a century. China has created a clear roadmap for magnetic confinement fusion development, where superconducting tokamaks will be used in commercial fusion reactors...
Article
Collapse of the edge flow shear as the line-averaged density approaches the Greenwald density limit has been observed as a precursor to the enhanced edge particle flux characteristic of proximity to the density limit regime. Here, we report the use of a biased electrode to sustain the edge shear layer in high density discharges, in which the shear...
Article
A newly designed divertor Langmuir probe diagnostic system has been installed in a rare closed divertor of the HL-2A tokamak and steadily operated for the study of divertor physics involved edge-localized mode (ELM) mitigation, detachment and redistribution of heat flux, etc. Two sets of probe arrays including 274 probe tips were placed at two port...
Article
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Tritium breeding blanket (TBB) is an essential component in a fusion reactor, which has functions of tritium breeding, energy generation, and neutron shielding. Tritium breeding ratio (TBR) is a key parameter to evaluate whether the TBB could produce enough tritium to achieve the tritium self-sufficiency (TBR >1) for fusion reactor. Current codes o...
Article
The artificial neural networks (NNs) are trained, based on the numerical database, to predict the no-wall and ideal-wall β N limits, due to onset of the n = 1 (n is the toroidal mode number) ideal external kink instability, for the HL-2M tokamak. The database is constructed by toroidal computations utilizing both the equilibrium code CHEASE and the...
Article
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 transpo...
Article
The active control of internal transport barriers (ITBs) is an important issue to achieve high performance plasma in a fusion reactor. A critical challenge of ITB control is to increase the ITB position. The ITBs with internal kink modes (IKMs), such as fishbone instability and long-live mode (LLM) with mode number of m/n = 1/1 are frequently obser...
Article
Enhanced particle transport events are discovered and analyzed as the density limit of the J-TEXT tokamak is approached. Edge shear layer collapse is observed and the ratio of Reynolds power to turbulence production decreases. Simultaneously, the divergence of turbulence internal energy flux (i.e. turbulence spreading) increases, indicating that sh...
Article
Full-text available
A tritium breeding blanket (TBB) is an essential component in a fusion reactor, which has functions of tritium breeding, energy generation and neutron shielding. Tritium breeding ratio (TBR) is a key parameter to evaluate whether the TBB could produce enough tritium to achieve tritium self-sufficiency (TBR > 1) for a fusion reactor. Current codes o...
Article
Full-text available
Blanket, including its first wall (FW), is one of the key components in the fusion reactor, which works in the severe condition with the huge high energy neutron irradiation, high heat flux and electromagnetic load. Facing these technical challenges for the blanket and its FW, Southwestern Institute of Physics is engaging in the development of the...
Article
Multiple broadband Alfvénic chirping modes (CMs), with frequencies in the wide range of f ∼ 35-150 kHz and chirping down rapidly, are found in HL-2A neutral beam injection plasmas, and the CMs can even coexist. The frequency chirping down process can be completed within ∼1 ms, and the frequency shift can reach 30-50 kHz. The CMs propagate in ion di...
Article
We reproduce nonlinear behaviors, including frequency chirping and mode splitting, referred to as bump-on-tail instabilities. As has been reported in previous works, the generation and motion of phase-space hole-clump pairs in a kinetically driven, dissipative system can result in frequency chirping. We provide examples of frequency chirping, both...
Article
The supersonic molecular beam injection (SMBI) technique is widely used in magnetic fusion devices for plasma fueling and active control of particles. The beam flow formed by the SMBI system is directly visualized by a newly established schlieren diagnostic system on the SMBI testing platform. This schlieren system could provide a 2D density distri...
Article
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The inward particle flux associated with the global long-lived mode (LLM) during the L-I-H transition on HL-2A tokamak has been measured. The inward particle flux arises from the phase change between density and radial velocity fluctuations, where density and velocity fluctuations are strongly correlated with magnetic fluctuations of LLM. Moreover,...
Article
An edge-coherent oscillation (ECO) with a bursting feature was observed in the steep-gradient pedestal region of H-mode plasmas in the HL-2A tokamak, where the type-I edge-localized modes (ELMs) were mitigated by application of n = 1 ( n is the toroidal mode number) resonant magnetic perturbation (RMP). Utilizing a newly developed beam emission spe...
Article
A radiofrequency (RF) ion source with a megawatt power extraction, thunder I, has been developed for the neutral beam injector (NBI) on HL-2A tokamak. A full solid-state RF generator with output power of 80 kW and frequency of 2 MHz was built by an RF combiner using 8 modules of solid-state RF generator with power of PRF = 10 kW. The line electric...
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Turbulent transport of impurity ions with hollow density profiles (HDPs), which are widely observed in magnetically confined plasmas and desirable for fusion reactor, is self-consistently investigated. A full gyrokinetic description is employed for main and impurity ions. Instead of conventional ion temperature gradient (ITG, including impurity ITG...
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Experimental investigations of thermal ions heat transport induced by reversed shear Alfvén eigenmodes (RSAEs) have been carried out on the HL-2A tokamak. It is found that the RSAEs are driven unstable by passing particles during the second half of sawtooth periods, and can not only degrade the bremsstrahlung radiations, but also cause obvious redu...
Article
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In this paper, the SF- (with the second X-point located near the outer target surface) in-out asymmetry and detachment bifurcation in HL-2M were explored by the edge plasma code SOLPS5.1 including electric but neglecting magnetic drifts. The modeling results reveal that the radial electric drift component (Epol × B) can play a key role on inducing...
Article
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HL-2M is a new medium-sized tokamak under construction at the Southwestern Institute of Physics, dedicated to supporting the critical physics and engineering issues of ITER and CFETR. Analyzing integrated plasma scenarios is essential for assessing performance metrics and foreseeing physics as well as the envisaged experiments of HL-2M. This paper...
Article
The Chinese Fusion Engineering Testing Reactor (CFETR), complementing the ITER facility, is aiming to demonstrate fusion energy production up to 200 MW initially and to eventually reach DEMO relevant power level 1 GW, to manifest a high duty factor of 0.3-0.5, and to pursue tritium self-sufficiency with tritium breeding ratio (TBR) >1. The key chal...
Article
A low-frequency electromagnetic mode (LF-mode) has been observed in a stellarator/heliotron device, Heliotron J. The LF-mode is observed only in neutral beam heated plasmas with a co-current, which increases the rotational transform. The observed LF-mode peaks at rho = 0.86-0.91, where rho = r/a is the normalized minor radius. The LF-mode propagate...
Article
System validation and density fluctuation calibration of phase contrast imaging (PCI) on an HL-2A tokamak are presented. Signals from different channels show not only a pronounced modulation of an incident laser beam induced by a sound wave, but also an excellent magnification and low image distortion of optics. The frequencywavenumber spectrum is...
Article
The tungsten spectrum in the extreme ultraviolet (EUV) wavelength range has been investigated in tokamak HL-2A to find line emissions from low-ionized tungsten ions which can be used for tungsten transport study in the plasma edge. For this purpose, tungsten is injected in the HL-2A plasma using the laser blow-off (LBO) technique with a newly devel...
Article
Electron cyclotron resonance heating and current drive (ECRH/ECCD) are deemed to be one of the best option to control the neoclassical tearing modes (NTMs), which are potential danger for steady state operation in fusion reactors. Recently, one of the two ECRH equatorial launchers on HL-2A tokamak has been upgraded to satisfy the real-time control...
Article
Depth profiling analysis for alloys which were corroded by liquid alkali metal can provide information on elemental distributions that is useful for determination of corrosion degree. In our work, laser induced breakdown spectroscopy (LIBS) was introduced to probe trends of elemental concentration in surface layer of weld type 316 L stainless steel...
Article
Er2O3 could be used to prevent the liquid alkalis corrosion as one candidate material for corrosion resistance coating in self-cooled blanket system of tokamak device. In our work, Er2O3 coatings were deposited on type 316 stainless steel substrates by direct current magnetic sputtering and corroded by liquid lithium for corrosion resistance study....
Article
Frequency chirping properties of Alfvén modes driven by energetic ions in HL-2A have been analyzed with a method based on the so-called Berk-Breizman model, which predicts that the interaction between wave, energetic ions and collision effects may exhibit steady-state, periodic, chaotic and explosive regimes. Nonlinear wave-particle interaction beh...
Article
In HL-2A, an inverse sawtooth oscillation is observed with a long-lasting m/n = 1/1 mode during ECRH phase with power deposition inside sawtooth inversion radius (inner-deposited ECRH), while a normal sawtooth instead appears when the ECRH power is deposited outside sawtooth inversion radius (outer-deposited ECRH). Aluminum is then injected as a tr...
Article
Kinetic Alfvén and pressure gradient driven instabilities are very common in magnetized plasmas, both in space and the laboratory. These instabilities will be easily excited by energetic particles (EPs) and/or pressure gradients in present-day fusion and future burning plasmas. This will not only cause the loss and redistribution of the EPs, but al...
Article
Effect of the pedestal deposited impurity on the edge-localized mode (ELM) behaviour has been observed and intensively investigated in the HL-2A tokamak. Impurities have been externally seeded by a newly developed laser blow-off (LBO) system. Both mitigation and suppression of ELMs have been realized by LBO-seeded impurity. Measurements have shown...
Article
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Dynamics of the pedestal between type-III ELMs have been studied by a particular designed four-step probe array on HL-2A tokamak. The recovery of the edge transport barrier (ETB) can be divided clearly into three different phases. Inconsistent with the dynamics during the type I ELMy discharge, our results on HL-2A show that the (electron) temperat...
Article
Systematic calibration experiment of Langmuir probe sheath potential coefficient λ, which is a critical coefficient for estimating plasma sheath potential, has been carried out in the HL-2A tokamak deuterium plasmas. The electron energy probability function (EEPF) shows that electron outside last-closed-flux-surface (LCFS) is Maxwell distribution,...
Article
The type of edge turbulence transition from resistive ballooning modes (RBM) to drift-type ion temperature gradient (ITG) modes has been observed in the gas puffing modulation experiments and also simulations at the HL-2A tokamak. The experimental evidence on RMB and ITG characteristics is given by Langmuir probe and Doppler reflectometry data. In...
Article
A phase contrast imaging (PCI) diagnostic has recently been developed on HL-2A tokamak. It can diagnose plasma density fluctuations with maximum wave number of 15 cm⁻¹ and wave number resolution of 2 cm⁻¹. The time resolution reaches 2 μs. A 10.6 μm CO2 laser is expanded to a beam with a diameter of 30 mm and injected into the plasma as an incident...
Article
The stability and performance of tokamak plasmas are routinely limited by various magneto-hydrodynamic instabilities, such as neoclassical tearing modes (NTMs). This paper presents a rather simple method to control the NTMs in real time (RT) on a tokamak, including the control principle of a feedback approach for RT suppression and stabilization fo...
Article
We report an experimental result on the stabilization of the energetic–ion driven internal kink mode (ion fishbone) by electron cyclotron resonance heating (ECRH), observed for the first time in a toroidal plasma. The mode asserts itself a resistive branch close to the marginal stability point. The resulting fishbone mode depends not only on the in...
Article
The China Fusion Engineering Test Reactor (CFETR) is the next device in the roadmap for the realization of fusion energy in China, which aims to bridge the gaps between the fusion experimental reactor ITER and the demonstration reactor (DEMO). CFETR will be operated in two phases. Steady-state operation and self-sufficiency will be the two key issu...
Article
Significant achievements have been made in the last 60 years in the development of fusion energy with the tokamak configuration. Based on the accumulated knowledge, the world is embarking on the construction and operation of ITER (International Thermonuclear Experimental Reactor) with a production of 500 MWf fusion power and the demonstration of ph...
Article
Multi-scale interactions have been observed recently in the HL-2A core NBI plasmas, including the synchronous coupling between kink mode and tearing mode, nonlinear couplings of TAE/BAE and TM near surface, AITG/KBM/BAE and kink mode near surface, and between kink mode and high-frequency turbulence. Experimental results suggest that several couplin...
Article
This paper discusses edge oscillatory plasma flows, geodesic acoustic mode (GAM) and limit cycle oscillations (LCOs), which have been measured by Doppler reflectometry prior to the high confinement mode (H-mode) in the HL-2A tokamak. The complex relations between the flows and background turbulence have been analyzed. It was observed that the GAM a...
Article
New mesoscale electric fluctuations (MSEFs) are identified in the edge plasmas of the HL-2A tokamak using multiple Langmuir probe arrays. The MSEFs, resulting from the synchronization and having components of dominant geodesic acoustic mode (GAM) and m/n = 6/2 potential fluctuations, are found at the same frequency as that of the magnetic fluctuati...
Article
Liquid metal lithium cause severe corrosion on the surface of metal structure material that used in the blanket and first wall of fusion device. Fast and accurate compositional depth profile measurement for the boundary layer of the corroded specimen will reveal the clues for the understanding and evaluation of the liquid lithium corrosion process...
Article
Since the last Fusion Energy Conference, significant progress has been made in the following areas. The first high coupling efficiency low-hybrid current drive (LHCD) with a passive–active multi-junction (PAM) antenna was successfully demonstrated in the H-mode on the HL-2A tokamak. Double critical impurity gradients of electromagnetic turbulence w...
Article
The strong fishbone mode (FB) and long-lived mode (LLM) have been observed during neutral beam injection (NBI) on the HL-2A tokamak. The FB and LLM can transit between each other. The LLM is identified as an internal kink mode (IKM) with the mode structure obtained using a newly developed electron cyclotron emission radiometer imaging (ECEI) system...
Conference Paper
Materials are the foundation for realizing fusion reactors, in which the in-vessel materials, such as plasma-facing materials, structural materials, and functional materials, are more critical since they will be exposed to high flux of edge plasma, high heat load, and 14 MeV neutron irradiations. Therefore, good performances at high temperatures an...
Article
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A research has been conducted to develop an 8MW electron cyclotron resonance heating and current drive (ECRH/ECCD) system on HL-2M tokamak. The ECRH system compromise eight 1MW gyrotrons, eight evacuated transmission lines and three launchers. The main purpose of the ECRH system was to suppress the neo-classical tearing modes and control the plasma...
Article
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Understanding the physics of energetic particles (EP) is crucial for the burning plasmas in next generation fusion devices such as ITER. In this work, three types of internal kink modes (a saturated internal kink mode (SK), a resonant internal kink mode (RK), and a double e-fishbone) excited by energetic particles in the low density discharges duri...
Article
A novel 16-channel fixed frequency Doppler backward scattering (DBS) reflectometer system has been developed on the HL-2A tokamak. This system is based on the filter-based feedback loop microwave source (FFLMS) technique, which has lower phase noise and lower power variation compared with present tunable frequency generation and comb frequency arra...
Article
Full-text available
On HL-2A, two different injections (supersonic molecular beam injection (SMBI) and pellet injection (PI)) are used to mitigate edge localized mode (ELM)-filament convective transport. The changes of their characteristics are studied in this paper. A high spatiotemporal resolution probe shows there are many similar phenomena, and the filament densit...