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Resonant magnetic perturbation (RMP) system is a powerful auxiliary system on tokamaks. On the J-TEXT tokamak, a set of new in-vessel coils is designed to enhance the amplitude of the RMP. The new coils are designed to be two-turn saddle coils. These two-turn saddle coils have been optimized in terms of their structure, support, and protection components to overcome the limitations of the narrow in-vessel space, resulting in a compact coil module that can be accommodated in the vessel. To verify the feasibility of this design, an electromagnetic simulation is performed to investigate the electrical parameters and the generated field of the coils. A multi-field coupled simulation is performed to investigate the capacity of heat dissipation. As a result of these efforts, the new RMP coils have been successfully installed on the J-TEXT tokamak. It has significantly enhanced the RMP amplitude and been widely applied in experiments.

The identification of magnetohydrodynamic (MHD) modes is a crucial issue in the control of magnetically confined plasmas. This paper proposes a novel method for identifying the evolution of MHD modes from a signal with a low signal-to-noise ratio. The proposed method generates a weighted directed graph from the time-frequency spectrum and calculates the evolution of the mode frequency by solving the shortest path. This method addresses the limitations posed by the lack of data channels and the disturbance of noise in the estimation of mode frequency and yields much better results compared to traditional methods. It is demonstrated that, using this method, the evolution of an unlocked tearing mode was more accurately calculated on the J-TEXT tokamak. This method remains feasible even with a low signal-to-noise ratio of 0.5, as shown by its uncertainty. Furthermore, with appropriate parameters, this method can be applied to not only signals with MHD modes, but also to general signals with continuous modes.

The coupling of multiple magnetohydrodynamic (MHD) modes can lead to mode locking and major disruption in tokamak plasmas. In the J-TEXT tokamak, the coupling between two small modes, i.e. m/n = 2/1 and 3/1 modes (m and n are poloidal and toroidal mode numbers, respectively), appears when the edge safety factor is reduced to the vicinity of 3. After the mode coupling, the toroidal phase difference between the 2/1 and 3/1 modes equals 0 in the low field side midplane. This phase relation of coupled modes leads to mutual destabilization and even major disruption. A control scheme to avoid disruption caused by coupled modes by resonant magnetic perturbations (RMPs) is presented. It is found that the application of RMP significantly changes the evolution of the coupled modes. The coupling of the 2/1 and 3/1 modes occurs earlier as the RMP amplitude increases. The RMP with moderate amplitude can suppress the growth of 2/1 and 3/1 coupled modes and hence avoid disruption. These results provide a possible strategy for the suppression of neoclassical tearing mode (NTM) seed islands on International Thermonuclear Experimental Reactor (ITER) or future fusion reactors.

In order to explore the deformation characteristics and stiffness degradation of loess near active faults under subway loading, a series of dynamic triaxial tests were utilized to model the effect of subway loading on loess near active faults. The cumulative plastic strain characteristics and stiffness degradation laws of loess under different dynamic stress amplitudes and different loading frequencies are obtained, and the cumulative plastic strain and stiffness degradation indices are fitted using empirical formulas and degradation models, respectively. The results show that the growth rate of cumulative plastic strain and the attenuation degree of stiffness degradation index are large under large dynamic stress amplitude and low loading frequency. And the empirical formula accurately fits the cumulative plastic strain curve, and the correlation coefficient is more than 0.9. Furthermore, the degradation model fits the stiffness degradation index curve well, and the degradation parameter increases with increasing dynamic stress amplitude and decrease with increasing frequency. The findings of the study can be used to guide the construction and safe operation of subway tunnels that traverse active faults.

The anisotropy of loess has been widely studied. However, most studies only consider the difference in soil quality and do not consider the impact of special areas. In addition, the conclusions of scholar researches are differences, and not representative. With the development of underground engineering construction, the direction of principal stress of loess is no longer just vertical, and the study of loess anisotropy has become a key issue. Therefore, this study takes the loess near-fault area of the Lishan piedmont fault as the research object, the differences of shear strength parameters in different directions were studied by routine triaxial shear test. The results show that the anisotropy of loess in this area is obviously different, which is greater than that of loess in other sites. The difference mainly reflect in the cohesion. The cohesion of the sample of the θ=90° is 1.62 times that of the sample of the θ=0° about. The difference of saturated loess is decreases, and the difference of cohesion is about 30%. The results provide a reference for the construction of the underground engineering for this areas, the engineering construction should pay attention to the difference in the strength and deformation on different directions of the loess.

The phase difference Δξ between locked islands (2/1 and 3/1) has been found to influence the heat transport on the 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 to excite coupled magnetic islands with different Δξ. The spectrum analysis shows that the current RMP coils on J-TEXT can only produce sufficient 2/1 and 3/1 RMP fields with a limited phase difference of Δξ∈[−75°, 75°]. In order to broaden the adjustable range of Δξ, a set of coils on the high field side (HFS) is proposed to generate 2/1 and 3/1 RMP fields with Δξ = 180°. As a result, RMPs with adjustable Δξ∈[−180°, 180°] and sufficient amplitudes could be achieved by applying the HFS coils and the low field side (LFS) coils. This work provides a feasible solution for flexible adjustment of the phase difference between m and m + 1 RMP, which might facilitate the study of major disruptions and their control.

The spectrum effect on the penetration of resonant magnetic perturbation (RMP) is studied with upgraded in-vessel RMP coils on J-TEXT. The poloidal spectrum of the RMP field, especially the amplitudes of 2/1 and 3/1 components, can be varied by the phase difference between the upper and lower coil rows, Δϕ = ϕ top−ϕ bottom, where ϕ top and ϕ bottom are the toroidal phases of the n = 1 field of each coil row. The type of RMP penetration is found to be related to Δϕ, including the RMP penetration of either 2/1 or 3/1 RMP and the successive penetrations of 3/1 RMP followed by the 2/1 RMP. For cases with penetration of only one RMP component, the penetration thresholds measured by the corresponding resonant component are close for various Δϕ. However, the 2/1 RMP penetration threshold is significantly reduced if the 3/1 locked island is formed in advance. The changes in the rotation profile due to 3/1 locked island formation could partially contribute to the reduction of the 2/1 thresholds.

The acceleration of the magnetic island rotation by the modulated resonant magnetic perturbation (MRMP) has been studied in J-TEXT tokamak experiments. After applying the MRMP, the phase difference between the tearing mode (TM) and MRMP, Δξ, oscillated near the effective phase difference, Δξ eff, which was defined as the time averaged value of Δξ. When the Δξ eff was closed to the—π/2, the MRMP only contributed an accelerating torque on the TM. As the result, the TM rotation frequency was increased by a few kilohertz for the optimized relative phase by small RMPs of the order of 10−5 of the toroidal field and the locked mode induced disruption was avoided. It is found that the TM rotation could be increased to a higher frequency by applying a stronger MRMP. There is a negative sinusoidal relationship between TM frequency and Δξ eff.

It is observed in EAST that the non-axisymmetric helical currents induced by lower hybrid waves (LHWs) in the scrape-off layer (SOL) can produce resonant magnetic perturbations (RMPs), hence mitigate edge-localized modes (ELMs) significantly and cause the strike points splitting. In this work, the non-axisymmetric SOL current driven by an alternative method, i.e. biased electrode, is shown to influence the plasma boundary, especially the strike points, in the divertor configuration on J-TEXT. With positive bias to the electrode, the upper strike points on the divertor target plate is observed to split as captured by the visible camera. Such splitting is usually observed with the RMPs. In addition, the SOL plasma parameters measured by the reciprocating probe, such as floating potential (V f), electron temperature (T e), and ion saturation current (I s), are significantly altered by applying modulation bias, which is closely related to the SOL current. A SOL current model has been extended from the limiter configuration version to the poloidal divertor configuration, and the magnetic field generated by SOL current and the change of magnetic topological structure of plasma boundary can be simulated. The simulation results shows that the magnetic perturbation generated by the SOL current can induce the lobes near the X-point, which is three-dimensional asymmetric structure, and shows good agreement with the experimental observation. The active control of the boundary magnetic topology indicates that the SOL current is capable of generating strong magnetic perturbations, and hence might be sufficient for the control of ELMs.

In the last two years, three major technical improvements have been made on J-TEXT in supporting of the expanded operation regions and diagnostic capabilities. (1) The successful commission of the 105 GHz/500 kW/1 s electron cyclotron resonance heating (ECRH) system increasing the core electron temperature from 0.9 keV up to around 1.5 keV. (2) The poloidal divertor configuration with an X-point in the high-field side has been achieved. In particular, the 400 kW electron cyclotron wave has also been successfully injected into the diverted plasma. (3) A 256-channel electron cyclotron emission imaging diagnostic system and two sets of four-channel Doppler backscattering diagnostics have been successfully developed on J-TEXT, allowing detailed measurement of the electron temperature and density fluctuations for turbulence and MHD research. The locked mode (LM), especially the 2/1 LM, is one of the biggest threats to the plasma operation. Both the thresholds of 2/1 and 3/1 LM are observed to vary non-monotonically on electron density. The electrode biasing was applied successfully to unlock the LM from either a rotating or static resonant magnetic perturbation (RMP) field. In the presence of 2/1 LM, three kinds of standing wave (SW) structures have been observed to share a similar connection to the island structure, i.e. the nodes of the SWs locate around the O- or X-points of the 2/1 island. The control and mitigation of disruption is essential to the safe operation of ITER, and it has been systematically studied by applying a RMP field, massive gas injection (MGI) and shattered pellet injection on J-TEXT. When the RMP-induced 2/1 LM is larger than a critical width, the MGI shutdown process can be significantly influenced. If the phase difference between the O-point of LM and the MGI valve is +90° (or −90°), the penetration depth and the assimilation of impurities can be enhanced (or suppressed) during the pre-thermal quench (TQ) phase and result in a faster (or slower) TQ. A secondary MGI can also suppress the runaway electron (RE) generation, if the additional high-Z impurity gas arrives at the plasma edge before TQ. When the secondary MGI has been applied after the formation of the RE current plateau, the RE current can be dissipated, and the dissipation rate increases with the injected impurity quantity but saturates with a maximum of 28 MA s−1. The non-local transport is experimentally observed in the ion transport channel. The electron thermal diffusivity significantly increases with the ECRH power. Theoretical work shows that significant intrinsic current can be driven by electromagnetic turbulence, and the robust formation mechanism of the E × B staircase is identified from the Hasegawa–Wakatani system.

Epilepsy is the second largest disease after headache in the neurology department of the hospital. Previous studies have shown that Xiao Chai Hu Tang (XCHT) has a certain therapeutic effect on epilepsy. We used the gene expression array data of epilepsy patients, and the relevant data of the Chinese medicine components in the TCMSP database and DrugBank database, combined with bioinformatics analysis methods, to construct herbs-compounds-targets (HCT) network and protein-protein interaction (PPI) core network of XCHT. The result suggests that Caveolin 1 (CAV1) may be a key target in the treatment of epilepsy, and β-carotene may have potential antiepileptic activity. In addition, the PPI core function network is enriched in the process of transcription factor regulation, and the related protein is located on the nuclear chromosome and closely related to the immune process, which provides a reference for other researchers.

The field penetration threshold of magnetic perturbations has been observed to vary nonmonotonically with an increase of density in ohmic plasmas on the J-TEXT tokamak. This observation appears contradicting the previous empirical density scaling law. Disentanglement of plasma density and rotation dependences of the field penetration threshold has been carried out. It shows that the field penetration threshold depends only weakly on the density but linearly on the plasma rotation. This result is not only important for the prediction of error field tolerance in fusion devices, but also opens a question on the role of density in the forced magnetic reconnection process in magnetized plasmas.

In view of the pollution problem of rain and sewage overflow in old urban area, the pollution characteristics and the pollution load are calculated and analysed, and then it is proposed that the initial rainwater storage technology be used to deal with the rainwater and sewage overflow. Based on the rainfall datas of years in Wuhan, and balance rainfall field controlling rate, annual runoff controlling rate and storage area to determine the initial rainfall storage standard. Then, the benefits of storage and disposal are forecasted. Finally, suggestions for further solving the problem of rain and sewage overflow pollution in the old city are put forward.

In this experiment, the whole fruit of passion fruit was used as raw material. The effects of the ratio of material to liquid (RML), the amount of sucrose addition and the pH on the quality of passion fruit juice beverage were investigated by single factor test. And the optimum process conditions of passion fruit juice beverage were determined by orthogonal test. The results show that the optimum process paramenters were as follow: RML was 1:3, pH was 4.0 and sucrose addition was 8%. Under such optimal conditions, the color of passion fruit juice beverage was red, the flavor of passion fruit was rich and it tasted pleasant.

Cascaded exploitation of diversion-type small hydropower (SHP) offers a source of new energy as well as socioeconomic benefits; however, it inevitably causes environmental disturbance and damage. Previous studies on the cumulative effect of cascaded diversion SHP rarely discussed using quantitative analysis method. In this paper, the ecological footprint analysis approach is proposed to assess the positive and negative impacts of cascaded diversion SHP on environment of a small-scale river in Southwest China. Positive impact is defined as ecological supply footprint (ESF), which refers to vegetation protection by replacing firewood with SHP. Negative impact is defined as ecological loss footprint (ELF), which includes fish and net primary productivity loss, vegetation destruction and soil erosion. With the raising in the number (n>4) of diversion SHP stations, the difference between ELF and ESF increases remarkably, suggesting that the adverse impacts of cascaded diversion SHP accumulate in the study area. Compared with vegetation destruction and soil erosion, the cumulative loss of fish and net productivity is the most important aspect of the adverse impacts which needs more attentions.