Simulation of impurity transport in the peripheral plasma due to the emission of dust in long pulse discharges on the Large Helical Device
TL;DR: In this article, two different plasma termination processes by dust emission were observed in long pulse discharges in the Large Helical Device, and the effect of the dust emission on the sustainment of the long-pulse discharges was investigated using a three-dimensional edge plasma transport code (EMC3-EIRENE) coupled with a dust transport code.
Abstract: Two different plasma termination processes by dust emission were observed in long pulse discharges in the Large Helical Device. One is a plasma termination caused by large amounts of carbon dust released from a lower divertor region. The other is termination caused by stainless steel (iron) dust emission from the surface of a helical coil can. The effect of the dust emission on the sustainment of the long pulse discharges are investigated using a three-dimensional edge plasma transport code (EMC3-EIRENE) coupled with a dust transport code (DUSTT). The simulation shows that the plasma is more influenced by the iron dust emission from the helical coil can than by the carbon dust emission from the divertor region. The simulation revealed that the plasma flow in divertor legs is quite effective for preventing dust from terminating the long pulse discharges.
Citations
More filters
15 citations
TL;DR: In this article, the authors evaluated and predicted the hazardous phenomenon of dust in the western strip of Iran using panel data-hybrid neural network and adaptive neuro-fuzzy inference system.
Abstract: Dust is a particulate matter in the atmosphere that is created by natural and human agents Dust has negative effects on various parts of human life, including agriculture, health and economics In recent decades, in various areas with a lack of rainfall and drought being contested, dust has happened there One of these areas is the northern part of the Persian Gulf in Iran which has been exposed to dust in recent years The purpose of the present study was to evaluate and predict the hazardous phenomenon of dust in the western strip of Iran Therefore, the data of dust from 14 synoptic stations of the study area (1990–2018) using panel data-hybrid neural network and adaptive neuro-fuzzy inference system (ANFIS) models were used Finally, TOPSIS and simple additive weighting (SAW) multi-criteria decision-making (MCDM) models were used to prioritize more dust-prone areas The results showed that the reliability of the panel data-hybrid neural network error estimation models is more than the ANFIS Based on prediction models, the highest probability of occurrence of the maximum dust in the future was observed at Sarpol-e Zahab and Abadan stations (128917 and 120709%, respectively) According to the SAW model, the highest probability of occurrence of dust was at Abadan station (998%) and based on the TOPSIS model, Eslamabad-e Gharb, with 997% It is necessary the inter-organizational cooperation by contracting an international memorandum with neighbouring countries in addition to domestic actions to reduce the damage caused by the dust phenomenon in the study area
12 citations
TL;DR: In this article, the authors used adaptive-network-based fuzzy inference systems (ANFIS) and the core of the radial base function (RBF) models to predict the hazardous dust phenomenon in dusty regions of Iran.
Abstract: In recent years, the damage caused by dust in different parts has increased dramatically. There are many dusty areas around the world. One of these regions in the southwest of Asia is Iran. The purpose of this study is to model and predict the hazardous dust phenomenon in dusty regions of Iran. For this purpose, dust data from 28 stations of intense dusty areas in Iran were collected at 29-year time intervals. Then, adaptive-network-based fuzzy inference systems (ANFIS) and the core of the radial base function (RBF) models were used for modelling and then the two models were compared to the future exact prediction. Finally, the dust data for all stations are prioritized using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multivariate decision-making model and output data are mapped by ArcGIS software. According to the results of this study, RMSE of the ANFIS model was 10.5 and the RBF model was 2.18. Therefore, the accuracy of RBF was more than the ANFIS model for prediction of the dust simulated in years, so the RBF model was used to predict. Based on the dust data obtained from the output of the RBF model in both the mean and maximum of dust abundance, the western and southwestern stations of the study areas were more exposed to dust in the future. Also, according to TOPSIS model, in the prioritization of stations involved with dust for simulated years, Abadan, Masjed Soleyman and Ahwaz were ranked by the amount of 100, 95% and 81%, respectively. Dust is one of the atmospheric phenomena that have adverse environmental effects and consequences. Dust storms have detrimental effects on the health and economy of society and climate change. Understanding the nature, origin and effects of dust storms plays an important role in determining its control methods.
4 citations
TL;DR: Monitoring aerosol temporal and spatial variations in Iran showed that aerosol values in terms of intensity and frequency of optical depth (AOD) increased over the 20-year time series, and its intensity was higher in the last 5 years.
Abstract: Natural hazards affect different parts of living organisms. One of these hazards is aerosols. Addressing this issue in areas that suffer from this hazard is of critical importance. Scientific research over the past two decades has shown that aerosol particles are one of the main pollutants from the perspective of public health and health. The purpose of the present study is to monitor and model aerosol temporal and spatial variations in Iran. Aerosols or airborne particles with health effects such as heart, vascular and respiratory diseases are associated. For this purpose, MODIS (or Moderate Resolution Imaging Spectroradiometer) and NOAA (or National Oceanic and Atmospheric Administration) satellite data and BTD (or Brightness Temperature Difference) were used. Given the 20-year study period (2000–2019), the output of much satellite data was divided into four five-year periods to monitor aerosols with high accuracy. The results showed that aerosol values in terms of intensity and frequency of optical depth (AOD) increased over the 20-year time series, and its intensity was higher in the last 5 years. According to the results obtained from the NODIS and NOAA satellite data and comparing their outputs, NOAA satellite data were associated with outliers, which was significantly different from the other cohort data. For this reason, the MODIS satellite image output was used to monitor aerosol images. The innovation of the present study is the use of remote sensing science to monitor the effects of aerosols on the environment and human’s health. According to the results from MODIS satellite data, the maximum optical depth (AOD) of the aerosols is for July 2003 with a value of 0.63, but according to the NOAA satellite data output, the maximum optical depth (AOD) of the aerosols is for March 2013 with a value of 2.54. As the values of aerosols increase in frequency and intensity and the areas with the highest intensity of aerosols have been identified, it can be overcome by careful planning of their problems. Areas, where the amount and volume of aerosols were higher, should be observed in health protocols. By preventing and maintaining good hygiene, the negative effects of aerosols can be reduced.
4 citations
1 citations
References
More filters
TL;DR: The EIRENE neutral gas transport Monte Carlo code has been developed initially for TEXTOR applications and can be used to solve more general linear kinetic transport equations by applying a stochastic rather than a numerical or analytical method of solution.
Abstract: The EIRENE neutral gas transport Monte Carlo code has been developed initially for TEXTOR since the early 1980s. It is currently applied worldwide in most fusion laboratories for a large variety of...
528 citations
TL;DR: In this article, the authors studied the transport of dust particles in tokamak fusion devices using computer simulations with the dust transport code, DUSTT, and showed that the dust particle can experience net deposition in relatively cold carbon-contaminated plasma regions.
Abstract: The transport of dust particles in tokamak fusion devices is studied using computer simulations with the dust transport code, DUSTT. Recent developments in modelling with the DUSTT code are reported. The improved model of dust dynamics in edge plasmas takes into account several additional effects, including thermionic and secondary electron emission which affects dust charging and heating, dust grain size effect on thermal radiation, and the presence of impurities in the plasma. It is shown that thermionic emission leads to enhanced dust heating by the plasma that boosts destruction of dust particles. The zone structure of tokamak plasmas is introduced for a qualitative analysis of dust survivability conditions. It is shown that a dust particle can experience net deposition in relatively cold carbon-contaminated plasma regions. Trajectories of sample dust particles in the DIII-D tokamak are simulated and analysed using the zone plasma description. Statistical averaging over an ensemble of particle trajectories is used to obtain spatial distributions of dust characteristics in the edge plasma of tokamaks. It is shown that transport of dust in tokamaks can significantly enhance penetration of carbon impurities towards the core plasma.
165 citations
TL;DR: In this article, a self-consistent treatment of impurity transport in the EMC3-EIRENE code has been implemented for high-density discharges in island divertors, with the downstream density never exceeding the upstream density.
Abstract: Basic plasma transport properties in island divertors are compared to those of standard tokamak divertors. A realistic plasma transport modelling of high-density discharges in island divertors has become possible by implementing a self-consistent treatment of impurity transport in the EMC3-EIRENE code. In contrast to standard tokamak divertors, the code predicts no high recycling prior to detachment, with the downstream density never exceeding the upstream density. This is mainly due to momentum losses arising from the cross-field transport associated with the specific island divertor geometry. This momentum loss is effective already at low densities, high temperatures and is responsible for the high upstream densities needed to achieve detachment. Numerical scans of carbon concentration for high-density plasma typically show first a smooth, then a sharp increase of the carbon radiation, the latter being accompanied by a sharp drop of the downstream temperature and density indicating detachment transition. The jumps of the radiation and temperature are due to a thermal instability associated with the form of the impurity cooling rate function and can be reproduced by a simple 1D radial energy model based on cross-field transport and impurity losses. This model is used as a guideline to illustrate and discuss the detachment physics in details, including detachment condition and thermal instability. Major EMC3-EIRENE code predictions have been verified by the first W7-AS divertor experiments. A comparison of calculations and measurements is presented for high-density, high-power W7-AS divertor discharges and the physics related to rollover and detachment is discussed in detail. The code has been recently extended to general SOL configurations with open islands and arbitrary ergodicity by using a new highly accurate field-line mapping technique. The method correctly reproduces flux surfaces and islands over a high number of toroidal field periods, thus ensuring a clear distinction between parallel and radial transport. The technique has been tested successfully on W7-AS, W7-X, LHD and TEXTOR DED, and first applied to solve the coupled heat conduction equations for a typical ergodic W7-AS configuration.
98 citations
TL;DR: In this article, an extended mesh system for EMC3-EIRENE has been developed to simulate peripheral plasma including the ergodic and the divertor leg regions of LHD.
Abstract: An extended mesh system for EMC3-EIRENE has been developed to simulate peripheral plasma including the ergodic and the divertor leg regions of LHD. Both the open and the closed divertor configurations are available. A series of simulations for 8MW input power, five different electron densities at the LCFS (last closed flux surface) and the open/closed configurations were carried out. Approximately 10 times larger neutral pressure was observed under the dome structure compared with the open configuration, which is in good agreement with experimental measurements. In the case of the closed configuration, the leg regions have a large contribution of ionization to hydrogen recycling. In the case of high density discharges, however, electron temperature in the legs becomes low and the major contribution of ionization moves to the ergodic region. Significant influence of configurations is observed in the inboard side of LHD, where closed divertor components are installed but little influence is seen near the LCFS. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
37 citations
TL;DR: In this article, a physical model for dust transport in tokamak devices is presented, as well as modeling results on dynamics of dust particles in plasma and conditions necessary for particle growth in plasma.
34 citations