Physics of Plasmas最新文献_第3页

Internal measurements of electromagnetic geodesic acoustic mode (GAM) in EAST plasmas EAST 等离子体中电磁测地声波模式 (GAM) 的内部测量

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0211489

Y. H. Wang, W. X. Ding, C. Zhou, A. D. Liu, X. Feng, H. Lian, H. Q. Liu, Y. Q. Chu, D. L. Brower, W. Z. Mao, J. L. Xie, L. T. Gao, R. J. Zhu, X. M. Zhong, H. J. Ren, Z. Chen, W. X. Shi, S. F. Wang

引用次数: 0

Propagation and stochastic dynamics of ion-temperature-gradient driven fluctuations 离子温度梯度驱动波动的传播和随机动力学

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0221923

Yihan Wang, Zhibin Guo

引用次数: 0

Phase retrieval for refraction-enhanced x-ray radiography using a deep neural network 利用深度神经网络进行折射增强型 X 射线放射摄影的相位检索

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0211331

S. Jiang, O. L. Landen, H. D. Whitley, S. Hamel, R. A. London, P. Sterne, S. B. Hansen, S. X. Hu, G. W. Collins, Y. Ping

{"title":"Phase retrieval for refraction-enhanced x-ray radiography using a deep neural network","authors":"S. Jiang, O. L. Landen, H. D. Whitley, S. Hamel, R. A. London, P. Sterne, S. B. Hansen, S. X. Hu, G. W. Collins, Y. Ping","doi":"10.1063/5.0211331","DOIUrl":"https://doi.org/10.1063/5.0211331","url":null,"abstract":"X-ray refraction-enhanced radiography (RER) or phase contrast imaging is widely used to study internal discontinuities within materials. The resulting radiograph captures both the decrease in intensity caused by material absorption along the x-ray path, as well as the phase shift, which is highly sensitive to gradients in density. A significant challenge lies in effectively analyzing the radiographs to decouple the intensity and phase information and accurately ascertain the density profile. Conventional algorithms often yield ambiguous and unrealistic results due to difficulties in including physical constraints and other relevant information. We have developed an algorithm that uses a deep neural network to address these issues and applied it to extract the detailed density profile from an experimental RER. To generalize the applicability of our algorithm, we have developed a technique that quantitatively evaluates the complexity of the phase retrieval process based on the characteristics of the sample and the configuration of the experiment. Accordingly, this evaluation aids in the selection of the neural network architecture for each specific case. Beyond RER, the model has potential applications for other diagnostics where phase retrieval analysis is required.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Transition characteristics, fluctuation evolution, and the role of coherent mode in electron cyclotron resonance heated low to high mode transition in KSTAR KSTAR 中电子回旋共振加热低模向高模转变的转变特性、波动演变和相干模式的作用

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0225207

Hogun Jhang, Minjun J Choi, Hyun-Seok Kim

{"title":"Transition characteristics, fluctuation evolution, and the role of coherent mode in electron cyclotron resonance heated low to high mode transition in KSTAR","authors":"Hogun Jhang, Minjun J Choi, Hyun-Seok Kim","doi":"10.1063/5.0225207","DOIUrl":"https://doi.org/10.1063/5.0225207","url":null,"abstract":"An experimental study is conducted on macro- and microscopic characteristics of low to high (LH) transition acquired by electron cyclotron resonance heating (ECRH) in KSTAR. A scan of pre-transition density demonstrates the existence of the characteristic minimum density, which requires minimum power to make LH transition. The minimum density in KSTAR shows a tendency to be lower than that evaluated from an empirical scaling law proposed by Ryter et al. [Nucl. Fusion 54, 083003 (2014)]. A comprehensive study of the evolution of low wavenumber electron temperature fluctuations is carried out using electron cyclotron emission imaging diagnostics. An analysis of the fluctuation amplitude in L-mode in terms of the electron collisionality and the electron temperature scaling length suggests that the dissipative trapped electron mode is likely to be a dominant instability before the LH transition. The fluctuation amplitude reduces first as the transition starts. A coherent mode that chirps down from 60 to 20 kHz emerges when the transition further develops. This coherent mode is then shown to revive turbulence that has been reduced significantly during the initial stage of the LH transition. The revival of turbulence could be a possible origin of the absence of the large edge localized mode when the coherent mode is persistent in ECRH-induced H-mode plasmas.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Current loss experiments of a conical MITL and PHC system on a megaampere-class LTD module 百万安培级 LTD 模块上锥形 MITL 和 PHC 系统的电流损耗实验

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0220464

Yaping Hong, Hao Wei, Jiachen Wang, Hanyu Wu, Liangping Wang, Chuangsi Cheng, Mo Li, Aici Qiu

{"title":"Current loss experiments of a conical MITL and PHC system on a megaampere-class LTD module","authors":"Yaping Hong, Hao Wei, Jiachen Wang, Hanyu Wu, Liangping Wang, Chuangsi Cheng, Mo Li, Aici Qiu","doi":"10.1063/5.0220464","DOIUrl":"https://doi.org/10.1063/5.0220464","url":null,"abstract":"A series of current transport experiments of a conical magnetically insulated transmission line (MITL) and a single post-hole convolute (PHC) had been done on a 12-stage linear transformer driver (LTD). The LTD produced a current with a rise time of about 120 ns and a peak varying from 0.5 to 0.8 MA depending on the terminated connection loads. The conical MITL was designed with a constant gap distance of 8 mm, which was equivalent to the MITL segments that are close to the PHC locations in the multi-level conical MITL in tens of megaampere current drivers. A single PHC was also designed to operate at conditions close to those fielded on tens of MA current drivers such as the Z machine. The experiment results indicated that there was almost no current loss along the constant-gap MITL before the peak current even the MITL figure of merit, i.e., E/cB varied from 0.1 to 1. However, the time when current trails appeared gradually advanced. The effects of the geometric sizes on the current transport efficiency of a single PHC were studied. It was indicated that the current transport efficiency of the single PHC was considerable high while the gap distance is larger than 6 mm. Whereas the PHC current loss was increased to about 30% when the gap is 3 mm. The dynamic impedance of the single PHC was obtained. During the pulse, as the plasma diffused, the convolute shunt impedance rapidly decreased, which was consistent with the known mechanism.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Density-gradient-driven drift waves in the solar corona 日冕中的密度梯度驱动漂移波

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0223417

M. Brchnelova, M. J. Pueschel, S. Poedts

{"title":"Density-gradient-driven drift waves in the solar corona","authors":"M. Brchnelova, M. J. Pueschel, S. Poedts","doi":"10.1063/5.0223417","DOIUrl":"https://doi.org/10.1063/5.0223417","url":null,"abstract":"It has been suggested that under solar coronal conditions, drift waves may contribute to coronal heating. Specific properties of the drift waves to be expected in the solar corona have, however, not yet been determined using more advanced numerical models. We investigate the linear properties of density-gradient-driven drift waves in the solar coronal plasma using gyrokinetic ion–electron simulations with the gyrokinetic code Gene, solving the Vlasov–Maxwell equations in five dimensions assuming a simple slab geometry. We determine the frequencies and growth rates of the coronal density gradient-driven drift waves with changing plasma parameters, such as the electron β, the density gradient, the magnetic shear, and additional temperature gradients. To investigate the influence of the finite Larmor radius effect on the growth and structure of the modes, we also compare the gyrokinetic simulation results to those obtained from drift-kinetics. In most of the investigated conditions, the drift wave has positive growth rates that increase with increasing density gradient and decreasing β. In the case of increasing magnetic shear, we find that from a certain point, the growth rate reaches a plateau. Depending on the considered reference environment, the frequencies and growth rates of these waves lie on the order of 0.1 mHz–1 Hz. These values correspond to the observed solar wind density fluctuations near the Sun detected by WISPR, currently of unexplained origin. As a next step, nonlinear simulations are required to determine the expected fluctuation amplitudes and the plasma heating resulting from this mechanism.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spatially resolved measurements of electron density of a magnetically confined split-ring resonator source 磁约束分环谐振源电子密度的空间分辨测量结果

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-04 DOI: 10.1063/5.0215171

Andrew T. Walsten, Brian Z. Bentz, Kevin Youngman, Kunning G. Xu

引用次数: 0

Relationship between cosmic ray intensity and Earth's magnetic field: Cross-wavelet analysis during intense and moderate geomagnetic storms 宇宙射线强度与地球磁场之间的关系：强烈和中等地磁暴期间的交叉小波分析

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-04 DOI: 10.1063/5.0201135

Chali Idosa Uga, Sujan Prasad Gautam, Binod Adhikari, Ashok Silwal, Ashutosh Giri

引用次数: 0

Trapping and detrapping of electrons in a typical DC glow discharge plasma under double layer condition 双层条件下典型直流辉光放电等离子体中的电子俘获和脱俘

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-04 DOI: 10.1063/5.0222639

Thangjam Rishikanta Singh, Sneha Latha Kommuguri, Suraj Kumar Sinha

{"title":"Trapping and detrapping of electrons in a typical DC glow discharge plasma under double layer condition","authors":"Thangjam Rishikanta Singh, Sneha Latha Kommuguri, Suraj Kumar Sinha","doi":"10.1063/5.0222639","DOIUrl":"https://doi.org/10.1063/5.0222639","url":null,"abstract":"Observation of a dip in plasma density with the rise of ion plasma waves demonstrates the process of detrapping electrons under the double-layer conditions in a DC glow discharge plasma. This study presents an experimental observation of self-excitation and interplay between electron and ion plasma waves when a high positive DC voltage (Vp∼+100 V) is applied to a planar probe immersed in plasma. For lower voltages (Vp∼+5 V), the electron sheath forms on the surface of the probe; however, for sufficiently high applied voltage, plasma could not supply the sufficient number of electrons to shield it from penetrating deep into the plasma. Therefore, the electron-deficient sheath attracts plasma electrons toward the probe, resulting in the excitation of plasma waves and the formation of double layers. Low energy streaming electrons get trapped in the double layers potential step. On ionization of background neutrals, trapped electrons get detrapped. It results in the excitation of ion waves and damping of electron plasma waves. The wavelet analysis of the observed floating potential fluctuations exhibits the interplay between electron and ion plasma waves. The trapping of electrons causes the excitation of electron plasma waves, and detrapping results in the excitation of ion plasma waves as overall electron density dips. It provides new insight into the nonlinear effects of the wave–wave interaction, the onset of Buneman instability, and streaming instability under the double-layer condition.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modifications to Swisdak (2013)'s rejection sampling algorithm for a Maxwell–Jüttner distribution in particle simulations 修改 Swisdak (2013) 粒子模拟中 Maxwell-Jüttner 分布的拒绝采样算法

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-04 DOI: 10.1063/5.0226859

Seiji Zenitani

引用次数: 0