Fast equilibrium reconstruction by deep learning on EAST tokamak

A deep neural network is developed and trained on magnetic measurements (input) and EFIT poloidal magnetic flux (output) on the EAST tokamak. In optimizing the network architecture, we use automatic optimization in searching for the best hyperparameters, which helps the model generalize better. We compare the inner magnetic surfaces and last-closed-flux surfaces (LCFSs) with those from EFIT. We also calculated the normalized internal inductance, which is completely determined by the poloidal magnetic flux and can further reflect the accuracy of the prediction. The time evolution of the internal inductance in full discharges is compared with that provided by EFIT. All of the comparisons show good agreement, demonstrating the accuracy of the machine learning model, which has the high spatial resolution as the off-line EFIT while still meets the time constraint of real-time control

A Novel Temperature Model of Regions Formed during the Preheating Stage of Belt Heating in Incremental Sheet Forming

The temperature of a forming region has a gradient distribution characteristic in the belt heating incremental sheet forming process, in which the relation between the heating power and the temperature distribution is ambiguous in the pre-heating stage. The setup of the heating power is therefore challenging, and the whole forming efficiency might decrease due to the above issue. Therefore, this paper proposes a belt heating method for electric conduction heating and presents a temperature calculation model for the forming region of the plate in the preheating state based on the heat conduction model. The calculated accuracy of the model is analysed through physical experiments, and the thermal transfer efficiency of heating tubes is analysed in detail. Based on the result, the thermal transfer efficiency value for heating tubes is determined to improve the accuracy of the suggested model. In addition, the effect of the model slope on the calculated result is further analysed, and the setting method of the slope value for the model is proposed according to different accuracy requirements

Model of defect formation in annealed undoped and Fe-doped liquid encapsulated Czochralski InP

Infrared absorption spectroscopy measurements indicate high concentration of hydrogen indium vacancy complex VInH4 in undoped and Fe-doped liquid encapsulated Czochralski (LEC) InP. Annealed undoped and Fe-doped semi-insulating (SI) InP are studied by room temperature Hall effect measurement and photocurrent spectroscopy. The results show that a mid gap donor defect and some shallow intrinsic defects are formed by high temperature annealing. This mid gap defect is shown to be phosphorus antisite related. Defect formation process and compensation mechanism in annealed SI InP are discussed.published_or_final_versio

Modelling of plasma response to 3D external magnetic field perturbations in EAST

Sustained mitigation and/or suppression of type-I edge localized modes (ELMs) has been achieved in EAST high-confinement plasmas, utilizing the resonant magnetic perturbation (RMP) fields produced by two rows of magnetic coils located just inside the vacuum vessel. Systematic toroidal modelling of the plasma response to these RMP fields with various coil configurations (with dominant toroidal mode number n = 1, 2, 3, 4) in EAST is, for the first time, carried out by using the MARS-F code (Liu et al 2000 Phys. Plasmas 7 3681), with results reported here. In particular, the plasma response is computed with varying coil phasing (the toroidal phase difference of the coil currents) between the upper and lower rows of coils, from 0 to 360°. Four figures of merit, constructed based on the MARS-F computations, are used to determine the optimal coil phasing. The modelled results, taking into account the plasma response, agree well with the experimental observations in terms of the coil phasing for both the mitigated and the suppressed ELM cases in EAST experiments. This study provides a crucial confirmation of the role of the plasma edge peeling response in ELM control, complementing similar studies carried out for other tokamak devices

The influence of instrumental line shape degradation on NDACC gas retrievals: Total column and profile

We simulated instrumental line shape (ILS) degradations with respect to typical types of misalignment, and compared their influence on each NDACC (Network for Detection of Atmospheric Composition Change) gas. The sensitivities of the total column, the root mean square (rms) of the fitting residual, the total random uncertainty, the total systematic uncertainty, the total uncertainty, degrees of freedom for signal (DOFs), and the profile with respect to different levels of ILS degradation for all current standard NDACC gases, i.e. O3, HNO3, HCl, HF, ClONO2, CH4, CO, N2O, C2H6, and HCN, were investigated. The influence of an imperfect ILS on NDACC gases’ retrieval was assessed, and the consistency under different meteorological conditions and solar zenith angles (SZAs) were examined. The study concluded that the influence of ILS degradation can be approximated by the linear sum of individual modulation efficiency (ME) amplitude influence and phase error (PE) influence. The PE influence is of secondary importance compared with the ME amplitude. Generally, the stratospheric gases are more sensitive to ILS degradation than the tropospheric gases, and the positive ME influence is larger than the negative ME. For a typical ILS degradation (10 %), the total columns of stratospheric gases O3, HNO3, HCl, HF, and ClONO2 changed by 1.9, 0.7, 4, 3, and 23 %, respectively, while the columns of tropospheric gases CH4, CO, N2O, C2H6, and HCN changed by 0.04, 2.1, 0.2, 1.1, and 0.75 %, respectively. In order to suppress the fractional difference in the total column for ClONO2 and other NDACC gases within 10 and 1 %, respectively, the maximum positive ME degradations for O3, HNO3, HCl, HF, ClONO2, CO, C2H6, and HCN should be less than 6, 15, 5, 5, 5, 5, 9, and 13 %, respectively; the maximum negative ME degradations for O3, HCl, and HF should be less than 6, 12, and 12 %, respectively; the influence of ILS degradation on CH4 and N2O can be regarded as being negligible

Industrial SO2 emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm

SO2 variability over a large concentration range and interferences from other gases have been major limitations in industrial SO2 emission monitoring. This study demonstrates accurate industrial SO2 emission monitoring through a portable multichannel gas analyzer with an optimized retrieval algorithm. The proposed analyzer features a large dynamic measurement range and correction of interferences from other coexisting infrared absorbers such as NO, CO, CO2, NO2, CH4, HC, N2O, and H2O. The multichannel gas analyzer measures 11 different wavelength channels simultaneously to correct several major problems of an infrared gas analyzer including system drift, conflict of sensitivity, interferences among different infrared absorbers, and limitation of measurement range. The optimized algorithm uses a third polynomial instead of a constant factor to quantify gas-to-gas interference. Measurement results show good performance in the linear and nonlinear ranges, thereby solving the problem that the conventional interference correction is restricted by the linearity of the intended and interfering channels. The results imply that the measurement range of the developed multichannel analyzer can be extended to the nonlinear absorption region. The measurement range and accuracy are evaluated through experimental laboratory calibration. Excellent agreement was achieved, with a Pearson correlation coefficient (r(2)) of 0.99977 with a measurement range from approximately 5 to 10 000 ppmv and a measurement error of less than 2 %. The instrument was also deployed for field measurement. Emissions from three different factories were measured. The emissions of these factories have been characterized by different coexisting infrared absorbers, covering a wide range of concentration levels. We compared our measurements with commercial SO2 analyzers. Overall, good agreement was achieved