A5020232612- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Educational Systems and Policies
- Technology and Data Analysis
- Internet of Things and Social Network Interactions
Huazhong University of Science and Technology
2022-2024
Abstract The J-TEXT capability is enhanced compared to two years ago with several upgrades of its diagnostics and the increase electron cyclotron resonance heating (ECRH) power 1 MW. With application wave (ECW), ECW assisted plasma startup achieved; tearing mode suppressed; toroidal injection 300 kW drives around 24 kA current; fast electrons are generated injected runaway current conversion efficiency increases ECRH power. coupling between 2/1 3/1 modes extensively studied. coupled usually...
Abstract A large number of runaway electrons (REs) generated during disruption will cause huge damage on next generation large-scale tokamak. The influence three-dimensional (3D) helical magnetic perturbations the suppression REs has been explored by a set 3D coils in J-TEXT tokamak, which can excite m/n = −2/2 perturbations. Experimental evidence shows that caused opposite coil current direct plasma towards high field side, simultaneously enhancing fluctuations, would enhance radial loss...
The phenomena of island healing and configuration transition induced by high-power electron cyclotron resonance heating (ECRH) have been investigated in the divertor on J-TEXT tokamak. Experimental results reveal that size edge open magnetic with mode number m/n = 3/1 decreases substantially under specific ECRH conditions. This process, referred to as healing, occurs when a power 500~600 kW is deposited plasma core or 250 at r 0.5 a, where minor radius. reduction width makes ineffective into...
Abstract The phenomena of island healing and configuration transition induced by high-power electron cyclotron resonance heating (ECRH) have been investigated in the divertor on J-TEXT tokamak. Experimental results reveal that size edge open magnetic with mode number m/n = 3/1 decreases substantially under specific ECRH conditions. This process, referred to as healing, occurs when a power 500~600 kW is deposited plasma core or 250 at r_EC 0.5 a, where minor radius. reduction width makes...
Abstract The coupling of multiple magnetohydrodynamic (MHD) modes can lead to mode locking and major disruption in tokamak plasmas. In the J-TEXT tokamak, between two small modes, i.e. m / n = 2/1 3/1 ( are poloidal toroidal numbers, respectively), appears when edge safety factor is reduced vicinity 3. After coupling, phase difference equals 0 low field side midplane. This relation coupled leads mutual destabilization even disruption. A control scheme avoid caused by resonant magnetic...
Abstract Magnetohydrodynamic (MHD) instabilities are widely observed during tokamak plasma operation. Magnetic diagnostics provide important information which supports the understanding and control of MHD instabilities. This paper presents current status magnetic dedicated to measuring at J-TEXT tokamak; consist five Mirnov probe arrays for high-frequency perturbations two saddle-loop low-frequency perturbations, such as locked mode. In recent years, several changes have been made these...
Abstract The spectrum effect on the penetration of resonant magnetic perturbation (RMP) is studied with upgraded in-vessel RMP coils J-TEXT. poloidal field, especially amplitudes 2/1 and 3/1 components, can be varied by phase difference between upper lower coil rows, Δ ϕ = top − bottom , where are toroidal phases n 1 field each row. type found to related including either or successive penetrations followed RMP. For cases only one component, thresholds measured corresponding component close...
Abstract Toroidal coupling between m / n = 2/1 and 3/1 modes frequently occurs in the J-TEXT, where ( ) is poloidal (toroidal) mode number. These coupled destabilize each other, leading to confinement degradation even triggering a major disruption. This paper presents two control strategies for preventing through application of proper static resonant magnetic perturbation (RMP) field. Experimental results demonstrate that moderate RMP can suppress small, rotating thus prevent modes. The...
Abstract A significant reduction of the external resonant magnetic perturbation (RMP) required for exciting locked mode (LM) has been observed experimentally due to presence an existing LM on J-TEXT. In a plasma with edge safety factor q slightly smaller than 3, 3/1 and 2/1 modes are be destabilized successively by rotating RMP field. The is excited first identified as kink mode, whose excitation threshold decreases operating increasing from 2.67 2.8 absence rational surface. Shortly after...
Abstract It is observed in EAST that the non-axisymmetric helical currents induced by lower hybrid waves (LHWs) scrape-off layer (SOL) can produce resonant magnetic perturbations (RMPs), hence mitigate edge-localized modes (ELMs) significantly and cause strike points splitting. In this work, SOL current driven an alternative method, i.e. biased electrode, shown to influence plasma boundary, especially points, divertor configuration on J-TEXT. With positive bias upper target plate split as...
Abstract The phase difference Δ ξ between locked islands (2/1 and 3/1) has been found to influence the heat transport on thermal quench during disruptions by numerical modeling [Hu Q et al 2019 Nucl. Fusion 59 , 016005]. To verify this experimentally, a set of resonant magnetic perturbation (RMP) coils is required excite coupled with different . spectrum analysis shows that current RMP J-TEXT can only produce sufficient 2/1 3/1 fields limited ∈[−75°, 75°]. In order broaden adjustable range...
Abstract It has been found that a higher-frequency rotating resonant magnetic perturbation (RRMP) can suppress large tearing mode (TM) and avoid subsequent disruption (Li et al 2020 Nucl. Fusion 60 056022). To clarify the mechanism of stabilizing effect RRMP, experiments on effects RRMPs with different frequencies TM amplitude are presented in this paper. After eliminating destabilizing statistical analysis reveals notable negative correlation between changes frequency. Further investigation...
Abstract Accurate measurement of the average plasma parameters in edge region, including temperature and density electrons ions, is critical for understanding characteristics scrape-off layer (SOL) divertor transport magnetically confined fusion research. On J-TEXT tokamak, a multi-channel retarding field analyzer (RFA) probe has been developed to study region under various poloidal island configurations. The radial profile ion-to-electron ratio, τ i/e , determined, which gradually decreases...
The rotating resonant magnetic perturbation (RMP) could lock the tearing mode (TM) and prevent disruption. It is found that TM instantaneous frequency oscillates during locking on RMP. In this work, oscillation was derived analytically based toroidal torque balance, which verified experimentally. two peaks with higher (2fTM0-fRMP) lower (fRMP) occurred in spectrum when window width of FFT shorter than oscillating period. Those were explained description frequency. independence temporal...
Plasma disruption in the tokamak is a huge threat to safe operation of ITER, which will cause serious damage device. At present, massive impurity injection main mitigation method, include gas (MGI) and shattered pellet (SPI) can dissipate most internal thermal energy via radiation. However, radiation asymmetry still device when it results concentration small area. It has been observed on many devices that n=1 mode strong influence asymmetry. In this paper, experimental J-TEXT have...
Abstract The behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations (RMPs) has been studied on a J-TEXT tokamak. main component RMPs is m / n = 2/1, where are numbers poloidal toroidal modes, respectively. During mode-locking caused by RMPs, it found that or major (if there no disruption), strong oscillations in both electron temperature density occur if edge safety factor q > 3. analysis shows 3/1 ode. In addition, using ECE,...
In order to investigate the effect of island divertor on peak heat load reduction in a tokamak, new was developed and installed J-TEXT tokamak. The engineering design takes into account complexity device based physical design, also needs ensure insulation performance coil. Before installing coil, electromagnetic forces conductors thermal conditions were simulated, force magnetic coil will not cause damage there be no failure behavior.