A.S. Liang
A5046273870- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- Precipitation Measurement and Analysis
- Radar Systems and Signal Processing
- Nuclear Physics and Applications
- Meteorological Phenomena and Simulations
Southwestern Institute of Physics
2017-2024
Forschungszentrum Jülich
2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2020
CEA Cadarache
2020
Abstract Since the last IAEA Fusion Energy Conference in 2018, significant progress of experimental program HL-2A has been achieved on developing advanced plasma physics, edge localized mode (ELM) control physics and technology. Optimization confinement performed. In particular, high- β N H-mode plasmas exhibiting an internal transport barrier have obtained (normalized pressure reached up to 3). Injection impurity improved confinement. ELM using resonance magnetic perturbation or injection a...
The radial profiles of perpendicular flows in the presence magnetic island were firstly measured HL-2A tokamak by hopping work frequency Doppler backward scattering reflectometer system along with a two-dimensional electron cyclotron emission imaging diagnostic identifying locations. It has been observed that across O-point cut flow is quite small at center and strongly enhanced around boundary island, resulting large increase shear outer half while X-point almost flat whole region....
The mission of HL-2A is to explore the key physical topics relevant ITER and advanced tokamak operation (e.g. future HL-2M), such as access H-mode, energetic particle physics, edge-localized mode (ELM) mitigation/suppression disruption mitigation. Since 2016 Fusion Energy Conference, team has focused on investigations following areas: (i) pedestal dynamics L–H transition, (ii) techniques ELM control, (iii) turbulence transport, (iv) physics. results demonstrated that increase mean shear flow...
Abstract The effect of lower hybrid current drive (LHCD) on edge velocity shear and turbulence in the HL-2A tokamak has been investigated. Experimental results demonstrate that LHCD leads to an increase at both inner outer layers, with magnitude increment found be proportional applied power. This enhancement is primarily attributed changes plasma pressure gradient induced by heating wave. In addition, also modifies edge, it observed higher wavenumbers exhibits a clear LHCD, whereas shows no...
Impurity seeding experiments in ELMy H-mode plasmas by using supersonic molecular beam injection (SMBI) have been performed the HL-2A tokamak. Besides pure impurity gas (neon, argon), impurities mixed with main ion fuelling different ratios were seeded into plasma. It has observed that ELM behavior and plasma confinement are very sensitive to ratio. For 30% Ne seeding, large ELMs replaced high frequency bursts (HFBs), which higher smaller amplitude compared peak heat load on divertor plate...
Abstract Since the first plasma realized in 2020, a series of key systems on HL-3 (known as HL-2M before) tokamak have been equipped/upgraded, including in-vessel components (the wall, lower divertor, and toroidal cryogenic/water-cooling/baking/glow discharge systems, etc.), auxiliary heating system 11 MW, 28 diagnostic (to measure density, electron temperature, radiation, magnetic field, etc.). Magnet field were commissioned firstly for divertor discharges. During 2nd experimental campaign...
Abstract Electron Cyclotron Emission Imaging (ECEI) is a critical diagnostic tool for measuring two-dimensional electron temperature fluctuations. The optical system, key component of the ECEI diagnostic, determines spatial resolution, field view, and imaging performance In this study, comprehensive laboratory tests characterizations including Local Oscillator (LO) coupling optics Radio Frequency (RF) receiving optics, were conducted to ensure optimal during plasma discharge experiments....
Abstract The application of resonant magnetic perturbation (RMP) with toroidal mode number n=1 on HL-3 tokamak inhibits the L-H transition at specific heating power. Following RMP application, electron density increases in outer plasma region (ρ>0.85, where ρ is normalized flux), while electron/ion temperature decreases. Notably, equilibrium flow shear edge substantially reduced. This reduction, combined enhanced micro-instabilities driven by increased profile gradients, leads to...
Abstract Improved energy confinement mode (I-mode) has been observed on the HL-2A tokamak. The I-mode features an edge transport barrier (ETB) in electron temperature and a low like density. A weakly coherent (WCM) is region with frequency of <?CDATA $f\sim 60{-}160$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>f</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>60</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> <mml:mn>160</mml:mn> </mml:math> kHz poloidal...
Abstract The evolutions of MHD instability behaviors and enhancement both electrostatic electromagnetic turbulence towards the plasma disruption have been clearly observed in HL-2A plasmas. Two types disruptive discharges investigated for similar equilibrium parameters: one with a distinct stage small central temperature collapse ( $$\sim$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>∼</mml:mo> </mml:math> 5–10%) around 1 millisecond before thermal quench (TQ), while...
The influence of resonant magnetic perturbations (RMPs) on the dynamics turbulence and flows at edge HL-2A tokamak is analyzed utilizing transfer entropy technique. results have shown that RMP damps poloidal as well E × B shearing rate, whereas enhances toroidal leads to a broadened particle spectrum with increased small scale transport. causality analysis indicates regulation impact flow turbulent fluctuations flux weakened, while rotation latter strengthened by field. changes in dominates...
Research on beta induced Alfvén eigenmodes (BAEs) driven by energetic ions has been carried out the HL-2A tokamak. The BAEs can be observed in cases of being beyond or below unity. mode frequencies are around 60–95 kHz. radial structures have detected multi-channel microwave reflectometer and soft x-ray arrays. results suggest that highly localized at normalized radius –0.26. Theoretical analyses based general fishbone-like dispersion relation code support experimental measurements both...
Turbulent fluctuations within a quasi-coherent frequency range (peak of ~ 130 kHz, ∆f ≈ tens kHz) are modulated by the rotation low tearing modes in core HL-2A ohmic plasmas. The (QCMs) emerge outside island boundary as O-point passes large cases (w > 4.5 cm), where local electron temperature profile is steepened. Statistical analysis shows that for QCM excitation, threshold value gradient identified and solely observed density discharges, consistent with linear confinement regime. These...
Dedicated experiments have been carried out at the J-TEXT tokamak for investigating plasma responses to externally applied resonant magnetic perturbation (RMP) field with various RMP currents under four different toroidal phases. After its penetration, dominant component of resonated q = 2 surface and excited an m/n 2/1 island, which rotated poloidally when changing phase RMP. The experimental results show significant influence on perpendicular rotations, density fluctuations geodesic...
Interactions among pedestal shear flows, turbulence, and the formation of edge transport barrier have been studied in H-mode plasmas HL-2A tokamak by multi-channel Doppler reflectometry with high spatiotemporal resolution. Geodesic acoustic mode (GAM) has observed during L-I-H transition. It that plasma transits into I-phase when mean E×B flow reaches a critical value. The bi-spectrum analysis shown there is strong interaction between GAM limit cycle oscillation (LCO), energy transfer from...
The Doppler backward scattering (DBS) reflectometer has become a well-established and versatile diagnostic technique for the measurement of density fluctuations flows in magnetically confined fusion experiments. In this work, novel multiple fixed-frequency array source with multiplexer is developed applied multi-channel DBS system. details system design laboratory tests are presented. Preliminary results shift frequency spectra measured by systems obtained. Characteristics plasma rotation...
The impact of supersonic molecular beam injection (SMBI) fuelling on the plasma turbulence and shear flows, which form a self-consistent state, has been studied in HL-2A tokamak. SMBI flattens layer by collisional flow damping increases intensity. It is found that can enhance non-linear regulation dynamics acts as an external tool for quench via stimulating two dynamic processes. SMBI-stimulated interactions facilitate L-H transition at marginal heating power accessing H-mode. effective...
Abstract Impurity seeding has been confirmed to be a potential way for edge localized modes (ELMs) mitigated in tokamaks. This paper mainly combines the integrated equilibria reconstruction framework and simulation codes such as BOUT++ dive deeper into mechanism of ELM mitigation by impurity injection. On one hand, injection changes pedestal pressure current profiles that are closely related activities. The nonlinear result shows size decreases factor 2 4 when exceeds threshold after other...
Abstract Instabilities in multiplies of ion cyclotron frequency range are identified and termed as core emission (ICE) recent HL-2A neutral beam injection heated experiments. Characteristics the ICE presented, including dependence harmonics features. The detected frequencies found to agree well with deuterium around magnetic axis. Additionally, exhibits a predominantly compressional property. Observations distinct spectrum features individual excitation each harmonic have demonstrated that...
As the plasma beta (β) increases in high-performance tokamaks, electromagnetic turbulence becomes more significant, potentially constraining their operational range. To investigate this turbulence, a cross-polarization scattering (CPS) diagnostic system is being developed on HL-3 tokamak for simultaneous measurements of density and magnetic fluctuations. In work, quasi-optical has been designed analyzed Q-band CPS diagnostic. The includes lens group beam waist size optimization, rotatable...
Abstract As the newly built tokamak in China, HL-3 will explore high-performance operation scenarios, such as super H-mode. The energy confinement and core parameters H-mode can be much larger than that normal Based on pedestal simulation code EPED, space of is obtained HL-3. Magnetic shear decreases with increasing triangularity; consequently, a achieved. threshold triangularity for accessing around 0.4. By using BOUT++, nonlinear study instabilities equilibrium executed first time....
The control of the edge localized mode (ELM) in tokamaks has been intensively investigated with different techniques. Recently, ELM impurity seeding also raised to be a hot topic. This paper reports effect laser blow-off on pedestal turbulence and ELMs. It found that seeded could have dual impacts instabilities, depending quantity injected impurity. enhances further mitigates ELMs when its exceeds lower threshold. Instead, impurities suppress particles reaches second higher observed ion...