Physics of Plasmas最新文献_第5页

Analysis of the role of the ion polarization current on the onset of pre-disruptive magnetic islands in JET 分析离子极化电流对 JET 中前破坏性磁岛发生的作用

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0189722

L. Bonalumi, E. Alessi, E. Lazzaro, S. Nowak, C. Sozzi, D. Frigione, L. Garzotti, E. Lerche, F. Rimini, D. van Eester

{"title":"Analysis of the role of the ion polarization current on the onset of pre-disruptive magnetic islands in JET","authors":"L. Bonalumi, E. Alessi, E. Lazzaro, S. Nowak, C. Sozzi, D. Frigione, L. Garzotti, E. Lerche, F. Rimini, D. van Eester","doi":"10.1063/5.0189722","DOIUrl":"https://doi.org/10.1063/5.0189722","url":null,"abstract":"The problem of the trigger of the neoclassical tearing mode is addressed in this work by evaluating the non-linear terms of the generalized Rutherford equation (GRE) for a set of JET disruptions. The linear stability index Δ′0, even for positive values, is not enough to describe the trigger of the mode as the stabilizing non-linear effects tend to prevent the growth of a mode below a certain width. First, an analysis on the contribution of the stabilizing effect of the curvature and the destabilizing effect of the bootstrap is done. Second, the work focuses on the role of the ion polarization current, a return current that flows parallel to the magnetic field due to the difference in the drift motion of the electrons and ions. This contribution is thought to play an important role in the onset of an island of width W, because it scales as 1/W3, making it a dominant term in the GRE when W is small. The assessment is carried out over a subset of pulses, producing interesting observations that were then generalized across the entire database, obtaining consistent results.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"142 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140760737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental validation of momentum transport theory in the core of H-mode plasmas in the ASDEX Upgrade tokamak ASDEX 升级型托卡马克中 H 模式等离子体核心动量传输理论的实验验证

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0203092

C. F. B. Zimmermann, C. Angioni, R. McDermott, B. P. Duval, R. Dux, E. Fable, A. Salmi, U. Stroth, T. Tala, G. Tardini, T. Pütterich

{"title":"Experimental validation of momentum transport theory in the core of H-mode plasmas in the ASDEX Upgrade tokamak","authors":"C. F. B. Zimmermann, C. Angioni, R. McDermott, B. P. Duval, R. Dux, E. Fable, A. Salmi, U. Stroth, T. Tala, G. Tardini, T. Pütterich","doi":"10.1063/5.0203092","DOIUrl":"https://doi.org/10.1063/5.0203092","url":null,"abstract":"This study employs the established momentum transport analysis at ASDEX Upgrade [Zimmermann et al., Nucl. Fusion 63, 124003 (2023)] to investigate the parametric variations of the momentum transport coefficients in the core of H-mode plasmas. These experimental results are compared to a comprehensive database of gyrokinetic calculations. Generally, good agreement between predicted and measured diffusive and convective transport coefficients is found. The predicted and measured Prandtl numbers correlate most dominantly with the magnetically trapped particle fraction. The experimentally inferred pinch numbers strongly depend on the logarithmic density gradient and magnetic shear, consistent with the theoretical predictions of the Coriolis pinch. The intrinsic torque from residual stress in the inner core is small, scales with the local logarithmic density gradient, and the data indicate a possible sign reversal. In the outer periphery of the core, the intrinsic torque is always co-current-directed and scales with the pressure gradient. This is consistent with prior experimental findings and global, non-linear gyrokinetic predictions. It suggests that profile shearing effects generate the intrinsic torque in the inner core. Toward the outer core, most likely, effects from E×B-shearing become more influential. These results offer the first comprehensive picture of this transport channel in the core plasma and contribute to validating the corresponding theoretical understanding. The derived scaling laws are used to construct a reduced momentum transport model, which has been validated against an additional dataset. This demonstrates that the model captures the essential contributions to momentum transport in the core of H-mode plasmas.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"355 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140781813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Reviewer acknowledgment for 2023 2023 年审稿人确认

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0208999

M. Mauel

引用次数: 0

Radiation transfer in the spectra of short-pulse laser-heated targets 短脉冲激光加热目标光谱中的辐射传递

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0191273

R. A. London, H. A. Scott, Madison E. Martin

引用次数: 0

Magnetoacoustic waves in a partially ionized astrophysical plasma with the thermal misbalance: A two-fluid approach 部分电离天体物理等离子体中的磁声波与热失衡：双流体方法

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0201945

N. Molevich, S. Pichugin, D. Riashchikov

{"title":"Magnetoacoustic waves in a partially ionized astrophysical plasma with the thermal misbalance: A two-fluid approach","authors":"N. Molevich, S. Pichugin, D. Riashchikov","doi":"10.1063/5.0201945","DOIUrl":"https://doi.org/10.1063/5.0201945","url":null,"abstract":"We consider the propagation of magnetoacoustic (MA) and acoustic waves of various frequency ranges in a partially ionized plasma at an arbitrary angle to the magnetic field, taking into account the influence of heating, radiative, and thermo-conductive cooling, as well as ion-neutral collisions. A dispersion equation that describes the evolution of nine modes was obtained in a compact mathematical form using the two-fluid model. The number and type of propagating waves (modified fast and slow MA waves, MA waves in the ion component, acoustic waves in the neutral component, as well as isothermal MA and isothermal acoustic waves) vary in different frequency ranges depending on the parameters of the medium. Analytical expressions are found for the speed and damping rates of all these propagating waves, and it is shown how dispersion and damping are formed by three processes: thermal misbalance, ion-neutral collisions, and thermal conductivity. Comparison of analytical calculations of the velocity and damping rates of MA waves with the numerical solution of the dispersion relation under conditions characteristic of the low solar atmosphere and prominences showed high accuracy of the obtained analytical expressions. The strong influence of thermal misbalance caused by gasdynamic perturbations on the speed and damping rate of modified magnetoacoustic waves in a strongly coupled region is shown as well.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"143 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140758706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental investigation of the characteristics of the plasma flow generated in quasi-stationary plasma accelerator using optical methods 用光学方法对准稳态等离子加速器中产生的等离子流特性进行实验研究

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0198341

A. A. Kartasheva, K. M. Gutorov, V. Podkovyrov, E. A. Muravyeva, K. S. Lukyanov, N. S. Klimov

{"title":"Experimental investigation of the characteristics of the plasma flow generated in quasi-stationary plasma accelerator using optical methods","authors":"A. A. Kartasheva, K. M. Gutorov, V. Podkovyrov, E. A. Muravyeva, K. S. Lukyanov, N. S. Klimov","doi":"10.1063/5.0198341","DOIUrl":"https://doi.org/10.1063/5.0198341","url":null,"abstract":"The spatial and temporal dependencies of the characteristics of the hydrogen plasma flow generated in quasi-stationary plasma accelerator were investigated. The spatiotemporal structure of discharge radiation in the interelectrode gap was studied. The range of changes in the length of the plasma glowing region in the interelectrode gap during the discharge pulse was determined. The region with bright plasma radiation located in the output face of the accelerator electrode system was observed. The presence of impurities and increased electron concentration values were observed in this region. Fluctuations in the radiation intensity of the plasma flow were detected along the entire length of its propagation. The spatial and temporal characteristics of these fluctuations were determined. The electron concentration values near the output face of the electrode system were obtained by measuring the Stark broadening of the Hβ line. For the first time, the time dependence of the electron concentration of free plasma flow was obtained using two methods simultaneously. The measurements were conducted at a distance, which significantly exceeds the characteristic size of the electrode system and where the influence of interelectrode processes of plasma flow generation is reduced. The first is based on measuring the Stark broadening of Hβ. As a second method, heterodyne interferometry was used.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"517 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140788079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Filamentary velocity scaling validation and spin dynamics in the DIII-D tokamak DIII-D 托卡马克中的丝状速度缩放验证和自旋动力学

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0195025

S. C. Molesworth, J. Boedo, C. Tsui, R. Perillo, D. Rudakov

引用次数: 0

Review of electron emission and electrical breakdown in nanogaps 纳米间隙中的电子发射和电击穿回顾

Physics of Plasmas Pub Date : 2024-04-01 DOI: 10.1063/5.0202607

Yimeng Li, L. Ang, Bing Xiao, F. Djurabekova, Yonghong Cheng, G. Meng

{"title":"Review of electron emission and electrical breakdown in nanogaps","authors":"Yimeng Li, L. Ang, Bing Xiao, F. Djurabekova, Yonghong Cheng, G. Meng","doi":"10.1063/5.0202607","DOIUrl":"https://doi.org/10.1063/5.0202607","url":null,"abstract":"With the continual miniaturization of electronic devices, there is an urgent need to understand the electron emission and the mechanism of electrical breakdown at nanoscale. For a nanogap, the complete process of the electrical breakdown includes the nano-protrusion growth, electron emission and thermal runaway of the nano-protrusion, and plasma formation. This review summarizes recent theories, experiments, and advanced atomistic simulation related to this breakdown process. First, the electron emission mechanisms in nanogaps and their transitions between different mechanisms are emphatically discussed, such as the effects of image potential (of different electrode's configurations), anode screening, electron space-charge potential, and electron exchange-correlation potential. The corresponding experimental results on electron emission and electrical breakdown are discussed for fixed nanogaps on substrate and adjustable nanogaps, including space-charge effects, electrode deformation, and electrical breakdown characteristics. Advanced atomistic simulations about the nano-protrusion growth and the nanoelectrode or nano-protrusion thermal runaway under high electric field are discussed. Finally, we conclude and outline the key challenges for and perspectives on future theoretical, experimental, and atomistic simulation studies of nanoscale electrical breakdown processes.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"157 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140758528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Impact of divertor neutral pressure on confinement degradation of advanced tokamak scenarios at ASDEX Upgrade 分流器中性压力对 ASDEX 升级版先进托卡马克方案约束退化的影响

Physics of Plasmas Pub Date : 2024-02-01 DOI: 10.1063/5.0184405

D. Silvagni, M. Dunne, T. Luda, A. Bock, A. Burckhart, R. Fischer, M. Griener, R. M. McDermott, U. Plank, T. Pütterich, M. Reisner, J. Stober, B. Tal, G. Tardini, H. Zohm

{"title":"Impact of divertor neutral pressure on confinement degradation of advanced tokamak scenarios at ASDEX Upgrade","authors":"D. Silvagni, M. Dunne, T. Luda, A. Bock, A. Burckhart, R. Fischer, M. Griener, R. M. McDermott, U. Plank, T. Pütterich, M. Reisner, J. Stober, B. Tal, G. Tardini, H. Zohm","doi":"10.1063/5.0184405","DOIUrl":"https://doi.org/10.1063/5.0184405","url":null,"abstract":"Over previous campaigns, an intense experimental program on advanced tokamak (AT) scenarios, has been carried out at the ASDEX Upgrade tokamak with full-tungsten wall. These discharges have been executed shortly after the boronization of the first wall to reduce the density and the impurity influx. The confinement level of such AT discharges was found to vary considerably, even when discharges with similar, if not identical, engineering parameters were carried out. This work investigates the causes of such confinement variations. Among all plasma quantities analyzed, confinement quality of AT scenarios correlates best with divertor neutral pressure, highlighting the key role of edge and scrape-off layer physics in determining global plasma confinement. In particular, it is found that the main cause of confinement degradation is the reduction of pedestal stability, which is in turn caused by the outward shift of the maximum density gradient position typically observed when the divertor neutral pressure increases. Owing to the low density of AT discharges under analysis, the movement of the maximum density gradient position can be caused entirely by changes in deuterium outgassing from the wall, which is strongly influenced by the boron layer deposited on the plasma-facing components and by the deuterium wall inventory. Finally, the predictive capability of confinement quality with the integrated model IMEP [Luda et al., Nucl. Fusion 60, 036023 (2020)] is tested on these discharges and shows promising results.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"149 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139821129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Divertor turbulent transport in the single null and snowflake in the TCV tokamak TCV 托卡马克中单个空洞和雪花中的湍流矢量输运

Physics of Plasmas Pub Date : 2024-02-01 DOI: 10.1063/5.0175437

C. Tsui, J. Boedo, J. Myra, D. Galassi, C. Wüthrich

{"title":"Divertor turbulent transport in the single null and snowflake in the TCV tokamak","authors":"C. Tsui, J. Boedo, J. Myra, D. Galassi, C. Wüthrich","doi":"10.1063/5.0175437","DOIUrl":"https://doi.org/10.1063/5.0175437","url":null,"abstract":"The relative importance of divertor radial turbulent particle fluxes is considered by comparing it against the fluxes in the main-chamber outer midplane (OMP) in a variety of conditions and divertor geometries in the tokamak à configuration variable. Within the first power falloff length, the radial turbulent fluxes in the leg of the outer divertor are consistently found to be small, and about 1/5th the magnitude measured at the OMP. In a low-density single null divertor, magnetic shear is found to play a strong role in isolating the main-chamber turbulence from the divertor. The snowflake divertor is purported to have turbulence-enhancing properties in the volume between the two X-points but was instead found to further reduce the divertor turbulent fluxes compared to the single null. Depending on the collisionality, the electric field fluctuations and radial turbulent fluxes were higher near the X-point than at the outer midplane, which is likely due to the binormal compression of the flux bundles consistent with analytical models of the resistive X-point mode. Density and potential fluctuation amplitudes decrease monotonically with distance from the OMP with a slope that depends on collisionality.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"38 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139965461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0