A5054023717- Magnetic confinement fusion research
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Superconducting Materials and Applications
- Laser-induced spectroscopy and plasma
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Meteorological Phenomena and Simulations
- Ion-surface interactions and analysis
- X-ray Spectroscopy and Fluorescence Analysis
Southwestern Institute of Physics
2014-2024
Durham University
2020
Culham Centre for Fusion Energy
2020
Culham Science Centre
2020
Australian National University
2020
University of Science and Technology of China
2020
Abstract Ion internal transport barriers (iITBs) are first observed in neutral beam injection (NBI) heated plasmas at the HL-2A tokamak. The position of barrier foot, stationary state, coincides with q = 1 surface within its uncertainty measurement. iITBs can develop more easily beginning NBI heating. Also, unstable for sawtooth plasma. Simulations reveal that thermal diffusivity ions ( χ i ) inside be as low neoclassical level. It is flow shear iITB state reaches level required suppressing...
A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. high throughput spectrometer (F/2.8) pitch-controlled fiber bundle enable temporal resolution of up to 400 Hz. The observation geometry an optimized optic highest radial ∼1 cm at edge. CXRS monitors carbon line emission (C VI, n 8-7, 529.06 nm) whose Doppler broadening...
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...
A 32/64-channel Charge eXchange Recombination Spectroscopy (CXRS) and a 7-channel motional Stark effect (MSE) polarimeter have been developed on the HL-2A tokamak. To extract maximum time resolution of system, incidence fibers spectrometer are pitch-controlled; double-slit fiber bundle can increase spatial channels with one charge-coupled device detector. The ion temperature plasma rotation resolutions up to 5 ms 1 cm obtained. Sawtooth oscillation, transition from intermediate phase (I...
Abstract The HL-2A tokamak has a very closed divertor geometry, and new infrared camera been installed for high resolution studies of edge-localized mode (ELM) heat load onto the outer targets. characteristics power deposition patterns on lower target plates during ELMs are systematically analysed with thermography. ELM energy loss is in range 3%–8% total plasma stored energy. peak flux targets currently achieved about 1.5–3.2 MW m −2 , wetted area 0.5–0.7 2 corresponding integrated decay...
Z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> is measured by two visible bremsstrahlung diagnostics on HL-2A tokamak, one of which uses a high spectral resolution spectrometer coupled with an electron multiplied CCD (temporal 100 Hz), and the other filterscope system 1 MHz). The brightness them coincides each very well. Z̅ systematically under different discharge conditions, such as divertor limiter configurations, ohmic auxiliary...
A shattered pellet injector based on in situ technology was installed the HL-2A tokamak, and preliminary experiments were performed recently. In this paper, a fast current shutdown experiment introduces injection (SPI). comparison with spontaneous disruptions massive gas injection, SPI has advantages for disruption mitigation. The experimental results show hard-X-ray radiation intensity (40 to 60 keV) rapidly falling from 20 0 when is used. From this, we can infer that runaway electrons are...
Abstract Recent progress towards an increased understanding of detached divertor physics has been made with the highly closed geometry in HL-2A. Non-intrinsic impurities were injected into outer chamber, and neutral pressure enhanced volumetric energy loss observed. Meanwhile main chamber decreased slightly, compression between greatly. This led to detachment a low upstream plasma line-averaged electron density ( <?CDATA $\sim0.5{n_{{\text{GW}}}}$?> <mml:math...
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...
A new Doppler coherence imaging spectroscopy interferometer has been developed on the HL-2A tokamak for scrape-off-layer impurity flow measurement. Its spatial resolution is estimated to be up ∼0.8 mm in horizontal direction and ∼9 vertical direction, with a field of view ∼34°. typical temporal about 1 ms. This salient feature allows time-resolved 2D measurements short-time phenomena HL-2A, such as edge localized modes. Group delay interference fringe pattern were calibrated dedicated...
A 7-channel motional Stark effect polarimeter based on four polarizers and a spectrometer has been developed in the HL-2A tokamak, which is first time successful utilizing this kind of tokamak. The accuracy angle can reach ±0.25° calibration experiments. Pilot experiments measuring magnetic pitch have successfully carried out weak plasma discharge with toroidal field ~1.3 T beam energy ~25 keV/amu. angles are obtained for 7 spatial points covering 24 cm along major radius resolution 40 ms;...
Abstract Edge localized mode (ELM) is successfully mitigated by helium and deuterium supersonic molecular beam injections (SMBIs) on HL-2A. During the ELM mitigation SMBIs, gradients of ion temperature ( T i ) electron density are softened in pedestal. It has been observed that averaged gradient decreases around 44% well depth radial electric field E r reduced SMBI during mitigation. Furthermore, at least 20% decrements have to be attained achieve a noticeable increase (decrease) frequency...
An experiment on edge localized modes (ELMs) during the vertical swing is performed in HL-2A tokamak. ELM mitigation observed when plasma moves upward. The column expands accompanied by a decrease both lower triangularity and absolute value of local magnetic shear at outer mid-plane upward moving. critical pressure gradient pedestal reduced for mitigating case according to linear simulation based peeling-ballooning theory. physics crash process also explored through nonlinear simulation. For...
L-shell electron-impact ionization (EII) cross sections for highly charged tungsten ions were measured at incident electron energies of 29.10 and 38.92 keV using the Shanghai-EBIT. Resolved x-rays from radiative recombination (RR) processes recorded with a high-purity Ge detector in static energy scanning mode. Absolute EII obtained by normalizing to theoretical RR sections. The experimental results compared calculated relativistic distorted-wave method implemented flexible atomic code Lotz...
Abstract A reduced-turbulence regime has been observed in HL-2A NBI-heated deuterium plasmas. The transition to this is achieved by injecting a certain amount of tungsten into the plasma based on laser blow-off technique. It found that amplitude geodesic acoustic mode (GAM) zonal flow and turbulent vortex size together with eddy tilting angle are all significantly increased edge region after injection. However, frequency GAM remains nearly unchanged. Measurement shows nonlinear coupling...
A qualitative model which includes three loops of zonal flow vs. turbulence and pressure gradient is proposed for the experimentally observed two types limit cycle oscillations (LCOs) low-intermediate-high (L-I-H) confinement transitions. The experimental evidences supporting revealing roles turbulence– pressure-gradient–induced flows in triggering H-mode at marginal heating power tokamak plasmas are presented. dominant role played by I-phase type-J LCO as well I-H transition demonstrated,...
Abstract The effect of impurity ions on the coupling between geodesic acoustic mode (GAM) zonal flow and local turbulent transport has been studied using a Langmuir probe array in HL-2A ohmically heated deuterium plasmas. experimental results illustrate that both frequency amplitude level GAM significantly reduce with increase carbon ion concentration, which is qualitatively consistent theoretical predictions (Xie et al 2018 Plasma Phys. Control. Fusion 60 025015). Meanwhile less energy...
Abstract Charge-exchange (CX) recombination spectroscopy is a powerful tool monitoring ion temperature and plasma rotation with good temporal spatial resolutions. A compact, new design for high-throughput, tri-band high spectral resolution spectrometer has been developed the charge-exchange measurement on HL-2A tokamak. The simultaneous measurements of He II (468.57 nm), C VI (529.1 D α (656.1 nm accompanied by beam emission spectra) an acquisition frequency up to 400 Hz are achieved...
Abstract Effect of impurity on edge turbulence was investigated the HL-2A tokamak by using Neon supersonic molecular beam injection (SMBI). For first time, a stationary radiative layer accompanied localized lasting more than 100ms is observed at region ρ=0.7-0.9. This duration much longer SMBI pulse length (1.2ms), indicating that diffusion whole cancelled out convection without spreading during this period. implies reversed from positive to negative density gradient region. reversal could...
Three visible imaging diagnostics, including a tangential view, an extreme wide-angle and downward-looking diagnostic, are installed on the HL-2M tokamak for high-performance plasmas. The entire field of view (FOV) covers up to 80% vacuum vessel. They aim at meeting requirements safe machine operation, plasma position identification, magnetohydrodynamic (MHD) instabilities study, so on. diagnostics based bilateral telecentric relay optics, while diagnostic utilizes guide bundle with large...