Despite the conclusion of the COVID-19 pandemic, the coronavirus-killing ability of cold atmospheric plasma (CAP) remains impressive, and investigations into its underlying mechanisms are still ongoing. The fusion peptide (FP) is a crucial site of membrane fusion and toxicity exerted by the S-protein in severe acute respiratory syndrome CoV-2 (SARS-CoV-2). In this study, reactive molecular dynamics simulations were performed to investigate the interaction mechanisms of FP and reactive oxygen species (ROS). The simulation results show that the given ROS (O atoms and OH radicals as examples) can destroy hydrophobic residues, negatively charged acidic residues, and peptide bonds through structurally altering essential sites. Furthermore, the reaction typically initiates from the H-abstraction reaction, followed by various types of oxidative modifications such as dehydrogenation, hydroxylation, carbonylation, cyclogenesis, ring cleavage, and decarboxylation, which are consistent with the experimental findings made on peptides. Therefore, it can be predicted that the membrane fusion ability of FP and the toxicity of SARS-CoV-2 will be reduced, with CAP functioning as a bactericidal disinfectant. The dose effects were also investigated, providing experimental guidance for the optimization of CAP. In this study, the interaction processes of FP and CAP are explored by revealing the chemical pathways and final reaction products from the computational data, thus providing a fundamental understanding of the mechanisms for inactivating SARS-CoV-2 by CAP.
尽管 COVID-19 大流行已经结束，但冷大气等离子体（CAP）杀灭冠状病毒的能力仍然令人印象深刻，对其潜在机制的研究仍在继续。融合肽（FP）是严重急性呼吸系统综合征冠状病毒 2 型（SARS-CoV-2）中 S 蛋白与膜融合并产生毒性的关键部位。本研究通过反应分子动力学模拟研究了 FP 与活性氧（ROS）的相互作用机制。模拟结果表明，给定的 ROS（以 O 原子和 OH 自由基为例）可通过改变重要位点的结构来破坏疏水残基、带负电的酸性残基和肽键。此外，该反应通常从 H-萃取反应开始，然后是各种类型的氧化修饰，如脱氢、羟基化、羰基化、环化、环裂解和脱羧，这与肽的实验结果是一致的。因此，可以预测，FP 的膜融合能力和 SARS-CoV-2 的毒性都会降低，而 CAP 则起到杀菌消毒的作用。此外，还研究了剂量效应，为优化 CAP 提供了实验指导。本研究通过从计算数据中揭示化学途径和最终反应产物，探索了 FP 和 CAP 的相互作用过程，从而从根本上了解了 CAP 灭活 SARS-CoV-2 的机制。
{"title":"Interaction mechanism of cold atmospheric plasmas and fusion peptides of spike protein in SARS-CoV-2 revealed by reactive molecular dynamics simulation","authors":"Yang Chen, Zhao-Nan Chai, Yuan-Tao Zhang","doi":"10.1063/5.0216072","DOIUrl":"https://doi.org/10.1063/5.0216072","url":null,"abstract":"Despite the conclusion of the COVID-19 pandemic, the coronavirus-killing ability of cold atmospheric plasma (CAP) remains impressive, and investigations into its underlying mechanisms are still ongoing. The fusion peptide (FP) is a crucial site of membrane fusion and toxicity exerted by the S-protein in severe acute respiratory syndrome CoV-2 (SARS-CoV-2). In this study, reactive molecular dynamics simulations were performed to investigate the interaction mechanisms of FP and reactive oxygen species (ROS). The simulation results show that the given ROS (O atoms and OH radicals as examples) can destroy hydrophobic residues, negatively charged acidic residues, and peptide bonds through structurally altering essential sites. Furthermore, the reaction typically initiates from the H-abstraction reaction, followed by various types of oxidative modifications such as dehydrogenation, hydroxylation, carbonylation, cyclogenesis, ring cleavage, and decarboxylation, which are consistent with the experimental findings made on peptides. Therefore, it can be predicted that the membrane fusion ability of FP and the toxicity of SARS-CoV-2 will be reduced, with CAP functioning as a bactericidal disinfectant. The dose effects were also investigated, providing experimental guidance for the optimization of CAP. In this study, the interaction processes of FP and CAP are explored by revealing the chemical pathways and final reaction products from the computational data, thus providing a fundamental understanding of the mechanisms for inactivating SARS-CoV-2 by CAP.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"40 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221856","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}
L. A. Bakaleinikov, V. I. Kuznetsov, E. Yu. Flegontova, D. P. Barsukov, I. K. Morozov
Steady state stability features of a diode with electrons and positrons entering from opposite boundaries and moving without collisions in plasma are numerically studied. The most complex regime when charged particles are reflected from potential barriers is considered. This problem arises, in particular, when modeling pulsar diodes. A small perturbation evolution is studied. It has been established that at the initial stage of the process the perturbation amplitude changes in time according to an exponential law. It is shown that stationary solutions with a potential barrier for electrons located near the electron-emitting electrode and a potential barrier for positrons located near the opposite electrode are stable when the inter-electrode distance is below a certain threshold. As the inter-electrode distance increases, the solutions become unstable. Solutions of another type when barriers reflecting particles are located in the opposite to the emitting electrode parts of the gap are also studied. However, these solutions turned out to be unstable.
{"title":"Steady state stability features of the electron–positron plasma diode in a mode with particle reflection from potential extrema","authors":"L. A. Bakaleinikov, V. I. Kuznetsov, E. Yu. Flegontova, D. P. Barsukov, I. K. Morozov","doi":"10.1063/5.0225861","DOIUrl":"https://doi.org/10.1063/5.0225861","url":null,"abstract":"Steady state stability features of a diode with electrons and positrons entering from opposite boundaries and moving without collisions in plasma are numerically studied. The most complex regime when charged particles are reflected from potential barriers is considered. This problem arises, in particular, when modeling pulsar diodes. A small perturbation evolution is studied. It has been established that at the initial stage of the process the perturbation amplitude changes in time according to an exponential law. It is shown that stationary solutions with a potential barrier for electrons located near the electron-emitting electrode and a potential barrier for positrons located near the opposite electrode are stable when the inter-electrode distance is below a certain threshold. As the inter-electrode distance increases, the solutions become unstable. Solutions of another type when barriers reflecting particles are located in the opposite to the emitting electrode parts of the gap are also studied. However, these solutions turned out to be unstable.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"60 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221857","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}
Num Prasad Acharya, Suresh Basnet, Amar P. Misra, Raju Khanal
We study the oblique propagation of weakly nonlinear dust–ion–acoustic (DIA) solitary waves (SWs) and shocks in collisional magnetized nonthermal dusty plasmas that are relevant in laboratory and space (Saturn's E-ring) environments. We consider plasmas to be composed of q-nonextensive hot electrons, thermal positive ions, and immobile negatively charged dust grains immersed in a static magnetic field and take into account the effects of ion creation (source), ion loss (sink), ion–neutral and ion–dust collisions, anisotropic ion pressure, and dust-charge fluctuations on the evolution of small-amplitude SWs and shocks. The ion–neutral collision enhancement equilibrium dust-charge number is self-consistently determined using Newton–Raphson method. We found that in laboratory dusty plasmas with adiabatic dust-charge variation [i.e., when the dust charging frequency (νch) is much higher than the dust–plasma oscillation frequency (ωpd)], the DIA solitary waves (DIASWs) get damped by the effects of the ion–dust and ion–neutral collisions, whereas the ion creation and ion loss lead to the amplification of solitary waves, and they appear as only compressive types with positive potential. On the other hand, in Saturn's E-ring plasmas, where the collisional and ion creation or ion loss effects are insignificant, the non-adiabaticity of dust-charge variation can give rise to the evolution of either damped DIASWs or DIA shocks, depending on the smallness of the ratios νch/ωpd or ωpd/νch, respectively. Furthermore, two critical values of the nonextensive parameter q exist, below (or above) which, the DIASWs and shocks can appear as rarefactive (or compressive) types. The characteristics of DIASWs and shocks are also analyzed numerically for parameters relevant to the laboratory and Saturn's E-ring plasmas.
我们研究了弱非线性尘埃-离子-声（DIA）孤波（SW）和冲击在碰撞磁化非热尘埃等离子体中的斜向传播，这与实验室和太空（土星的 E 环）环境相关。我们认为等离子体是由浸没在静态磁场中的q-nonextensive热电子、热正离子和不动的带负电尘粒组成的，并考虑了离子产生（源）、离子损失（汇）、离子-中性碰撞和离子-尘粒碰撞、各向异性离子压力和尘粒电荷波动对小振幅SW波和冲击演化的影响。利用牛顿-拉斐森方法自洽地确定了离子-中性碰撞增强平衡尘荷数。我们发现，在绝热尘埃电荷变化的实验室尘埃等离子体中[即尘埃电荷频率（νch）远高于尘埃等离子体振荡频率（ωpd）时]，DIA孤波（DIASWs）会被离子-尘埃和离子-中性碰撞的影响所阻尼，而离子的产生和离子的损耗会导致孤波的放大，它们仅以正电势的压缩类型出现。另一方面，在土星的 E 环等离子体中，碰撞和离子产生或离子损耗的影响并不显著，尘埃电荷变化的非绝热性可能导致阻尼 DIASW 或 DIA 冲击的演化，这分别取决于 νch/ωpd 或 ωpd/νch 的比率是否很小。此外，非广延性参数 q 存在两个临界值，低于（或高于）这两个临界值，DIASW 和冲击可以表现为稀疏（或压缩）类型。我们还根据与实验室和土星 E 环等离子体相关的参数对 DIASW 和冲击的特征进行了数值分析。
{"title":"Dust–ion–acoustic damped solitary waves and shocks in laboratory and Saturn's E-ring magnetized nonthermal dusty plasmas with anisotropic ion pressure and dust-charge fluctuation","authors":"Num Prasad Acharya, Suresh Basnet, Amar P. Misra, Raju Khanal","doi":"10.1063/5.0220030","DOIUrl":"https://doi.org/10.1063/5.0220030","url":null,"abstract":"We study the oblique propagation of weakly nonlinear dust–ion–acoustic (DIA) solitary waves (SWs) and shocks in collisional magnetized nonthermal dusty plasmas that are relevant in laboratory and space (Saturn's E-ring) environments. We consider plasmas to be composed of q-nonextensive hot electrons, thermal positive ions, and immobile negatively charged dust grains immersed in a static magnetic field and take into account the effects of ion creation (source), ion loss (sink), ion–neutral and ion–dust collisions, anisotropic ion pressure, and dust-charge fluctuations on the evolution of small-amplitude SWs and shocks. The ion–neutral collision enhancement equilibrium dust-charge number is self-consistently determined using Newton–Raphson method. We found that in laboratory dusty plasmas with adiabatic dust-charge variation [i.e., when the dust charging frequency (νch) is much higher than the dust–plasma oscillation frequency (ωpd)], the DIA solitary waves (DIASWs) get damped by the effects of the ion–dust and ion–neutral collisions, whereas the ion creation and ion loss lead to the amplification of solitary waves, and they appear as only compressive types with positive potential. On the other hand, in Saturn's E-ring plasmas, where the collisional and ion creation or ion loss effects are insignificant, the non-adiabaticity of dust-charge variation can give rise to the evolution of either damped DIASWs or DIA shocks, depending on the smallness of the ratios νch/ωpd or ωpd/νch, respectively. Furthermore, two critical values of the nonextensive parameter q exist, below (or above) which, the DIASWs and shocks can appear as rarefactive (or compressive) types. The characteristics of DIASWs and shocks are also analyzed numerically for parameters relevant to the laboratory and Saturn's E-ring plasmas.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"175 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221855","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}
Swadesh M. Mahajan, Prerana Sharma, Manasvi Lingam
It is demonstrated through a succinct derivation as to how the linear waves in Hall magnetohydrodynamics (HMHD) constitute a fundamental departure from the standard MHD waves. Apart from modifying the conventional MHD spectrum, the Hall current induces a distinct and new branch consisting of purely circularly polarized waves that may become the representative shear waves.
{"title":"Hall MHD waves: A fundamental departure from their MHD counterparts","authors":"Swadesh M. Mahajan, Prerana Sharma, Manasvi Lingam","doi":"10.1063/5.0227375","DOIUrl":"https://doi.org/10.1063/5.0227375","url":null,"abstract":"It is demonstrated through a succinct derivation as to how the linear waves in Hall magnetohydrodynamics (HMHD) constitute a fundamental departure from the standard MHD waves. Apart from modifying the conventional MHD spectrum, the Hall current induces a distinct and new branch consisting of purely circularly polarized waves that may become the representative shear waves.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"433 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221854","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}
Hee-Jung Yeom, Gwang-Seok Chae, Min Young Yoon, Wooram Kim, Jae-Heon Lee, Jun-Hyung Park, Chan-Woo Park, Jung-Hyung Kim, Hyo-Chang Lee
Real-time monitoring of plasma parameters at the wafer plane is important because it significantly affects the processing results, yield enhancement, and device integrity of plasma processing. Various plasma diagnostic sensors, including those embedded in a chamber wall and on-wafer sensors, such as flat-cutoff sensors, have been developed for plasma measurements. However, to measure the plasma density on the wafer surface in real-time when processing plasma with bias power, such as in the semiconductor etching process, one must analyze the transmission spectrum of the flat-cutoff sensor in an environment with bias power applied. In this study, the transmission-spectrum and measured plasma-density characteristics of an electrode-embedded flat-cutoff sensor are analyzed via electromagnetic simulations and experiments under applied bias power. Our findings indicate that the flat-cutoff sensor accurately measures the plasma density, which is equivalent to the input plasma density under low bias power. Conversely, under high bias power, the plasma density measured by the sensor is lower than the input plasma density. Also, a thick-sheath layer is formed owing to the high bias power, which may complicate the measurement of plasma parameters using the flat-cutoff sensor. Plasma diagnostics using a flat-cutoff sensor in thick-sheath environments can be achieved by optimizing the flat-cutoff sensor structure. Our findings can enhance the analysis of plasma parameters on-wafer surfaces in processing environments with bias power applied.
{"title":"Effect of radiofrequency bias power on transmission spectrum of flat-cutoff sensor in inductively coupled plasma","authors":"Hee-Jung Yeom, Gwang-Seok Chae, Min Young Yoon, Wooram Kim, Jae-Heon Lee, Jun-Hyung Park, Chan-Woo Park, Jung-Hyung Kim, Hyo-Chang Lee","doi":"10.1063/5.0221016","DOIUrl":"https://doi.org/10.1063/5.0221016","url":null,"abstract":"Real-time monitoring of plasma parameters at the wafer plane is important because it significantly affects the processing results, yield enhancement, and device integrity of plasma processing. Various plasma diagnostic sensors, including those embedded in a chamber wall and on-wafer sensors, such as flat-cutoff sensors, have been developed for plasma measurements. However, to measure the plasma density on the wafer surface in real-time when processing plasma with bias power, such as in the semiconductor etching process, one must analyze the transmission spectrum of the flat-cutoff sensor in an environment with bias power applied. In this study, the transmission-spectrum and measured plasma-density characteristics of an electrode-embedded flat-cutoff sensor are analyzed via electromagnetic simulations and experiments under applied bias power. Our findings indicate that the flat-cutoff sensor accurately measures the plasma density, which is equivalent to the input plasma density under low bias power. Conversely, under high bias power, the plasma density measured by the sensor is lower than the input plasma density. Also, a thick-sheath layer is formed owing to the high bias power, which may complicate the measurement of plasma parameters using the flat-cutoff sensor. Plasma diagnostics using a flat-cutoff sensor in thick-sheath environments can be achieved by optimizing the flat-cutoff sensor structure. Our findings can enhance the analysis of plasma parameters on-wafer surfaces in processing environments with bias power applied.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"62 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221816","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}
M. Chernyshova, K. Malinowski, K. Mikszuta-Michalik, S. Jabłoński, M. Jagielski
This work addresses the development of diagnostics for core plasma radiated power and soft x-ray intensity measurements, which will be useful in future fusion reactors to ensure reliable plasma control (by monitoring the power loss across the separatrix) in accordance with the DEMO control requirements. For this purpose, we look into the development of such a detection system that will provide the required information via soft x-ray diagnostics. The target photon range for such a detecting system is considered to be 3–50 keV. The aspects of the development have included detailed diagnostics design, physics, engineering and integration studies, as well as an investigation into the feasibility and performance of the diagnostics and its components. The development is currently in the design phase. Nevertheless, the answer is already needed regarding the fulfillment of system requirements. In order to monitor the power crossing the separatrix, a precise estimation of the plasma radiation is needed to maintain the high-efficiency plasma. This requires strict measurement accuracy criteria, with 3% accuracy margin for the core plasma radiated power estimate and 5% noise for a single measurement of a single detector within the detector array. Here, an initial estimation of the detecting system's accuracy was provided based on an analysis of both the tomography reconstruction and detector measurement capabilities. The optimal number of lines of sight for tomography reconstruction was found for the considered plasma field of view. Additionally, the initial concept for a photon-sensitive chamber of the detecting system was developed. This allowed for the assessment of the predicted measurement accuracy of the detector for horizontal and vertical lines of sight.
这项工作旨在开发核心等离子体辐射功率和软 X 射线强度测量诊断系统，这将有助于未来的聚变反应堆按照 DEMO 控制要求确保可靠的等离子体控制（通过监测分离矩阵的功率损耗）。为此，我们将研究开发这样一种探测系统，通过软 X 射线诊断提供所需的信息。这种探测系统的目标光子范围为 3-50 千伏。开发工作包括详细的诊断设计、物理、工程和集成研究，以及对诊断及其组件的可行性和性能进行调查。研发工作目前正处于设计阶段。不过，在满足系统要求方面已经有了答案。为了监测穿过分离矩阵的功率，需要对等离子体辐射进行精确估算，以保持高效等离子体。这需要严格的测量精度标准，核心等离子体辐射功率估算的精度裕度为 3%，探测器阵列中单个探测器的单次测量噪声为 5%。在此，根据对层析成像重建和探测器测量能力的分析，对探测系统的精度进行了初步估算。针对所考虑的等离子体视场，找到了用于层析成像重建的最佳视线数量。此外，还提出了探测系统光子敏感室的初步概念。这样就可以评估探测器对水平和垂直视线的预测测量精度。
{"title":"Conceptual research on meeting tomographic reconstruction and measurement accuracy requirements: Key factors in the development of a radiated power diagnostics for DEMO","authors":"M. Chernyshova, K. Malinowski, K. Mikszuta-Michalik, S. Jabłoński, M. Jagielski","doi":"10.1063/5.0209330","DOIUrl":"https://doi.org/10.1063/5.0209330","url":null,"abstract":"This work addresses the development of diagnostics for core plasma radiated power and soft x-ray intensity measurements, which will be useful in future fusion reactors to ensure reliable plasma control (by monitoring the power loss across the separatrix) in accordance with the DEMO control requirements. For this purpose, we look into the development of such a detection system that will provide the required information via soft x-ray diagnostics. The target photon range for such a detecting system is considered to be 3–50 keV. The aspects of the development have included detailed diagnostics design, physics, engineering and integration studies, as well as an investigation into the feasibility and performance of the diagnostics and its components. The development is currently in the design phase. Nevertheless, the answer is already needed regarding the fulfillment of system requirements. In order to monitor the power crossing the separatrix, a precise estimation of the plasma radiation is needed to maintain the high-efficiency plasma. This requires strict measurement accuracy criteria, with 3% accuracy margin for the core plasma radiated power estimate and 5% noise for a single measurement of a single detector within the detector array. Here, an initial estimation of the detecting system's accuracy was provided based on an analysis of both the tomography reconstruction and detector measurement capabilities. The optimal number of lines of sight for tomography reconstruction was found for the considered plasma field of view. Additionally, the initial concept for a photon-sensitive chamber of the detecting system was developed. This allowed for the assessment of the predicted measurement accuracy of the detector for horizontal and vertical lines of sight.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"14 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221858","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}
Plasmoid instability accelerates reconnection in collisional plasmas by transforming a laminar reconnection layer into numerous plasmoids connected by secondary current sheets in two dimensions (2D) and by fostering self-generated turbulent reconnection in three dimensions (3D). In large-scale astrophysical and space systems, plasmoid instability likely initiates in the collisional regime but may transition into the collisionless regime as the fragmentation of the current sheet progresses toward kinetic scales. Hall magnetohydrodynamics (MHD) models are widely regarded as a simplified yet effective representation of the transition from collisional to collisionless reconnection. However, plasmoid instability in 2D Hall MHD simulations often leads to a single-X-line reconnection configuration, which significantly differs from fully kinetic particle-in-cell simulation results. This study shows that single-X-line reconnection is less likely to occur in 3D compared to 2D. Moreover, depending on the Lundquist number and the ratio between the system size and the kinetic scale, Hall MHD can also realize 3D self-generated turbulent reconnection. We analyze the features of the self-generated turbulent state, including the energy power spectra and the scale dependence of turbulent eddy anisotropy.
等离子体不稳定性通过在二维（2D）范围内将层状再连接层转化为由次级电流片连接的无数等离子体，以及在三维（3D）范围内促进自生湍流再连接，从而加速碰撞等离子体中的再连接。在大尺度天体物理和空间系统中，质点不稳定性很可能始于碰撞机制，但随着电流片的破碎向动力学尺度发展，可能会过渡到无碰撞机制。霍尔磁流体动力学（MHD）模型被广泛认为是碰撞再连接向无碰撞再连接过渡的一种简化但有效的表示方法。然而，二维霍尔 MHD 模拟中的质点不稳定性往往会导致单 X 线再连接构造，这与全动力学粒子-胞室模拟结果有很大不同。本研究表明，与二维相比，单X线再连接在三维中发生的可能性较小。此外，根据伦奎斯特数和系统大小与动力学尺度之间的比例，霍尔 MHD 也可以实现三维自生湍流重联。我们分析了自生湍流状态的特征，包括能量功率谱和湍流涡各向异性的尺度依赖性。
{"title":"Three-dimensional plasmoid-mediated reconnection and turbulence in Hall magnetohydrodynamics","authors":"Yi-Min Huang, Amitava Bhattacharjee","doi":"10.1063/5.0216561","DOIUrl":"https://doi.org/10.1063/5.0216561","url":null,"abstract":"Plasmoid instability accelerates reconnection in collisional plasmas by transforming a laminar reconnection layer into numerous plasmoids connected by secondary current sheets in two dimensions (2D) and by fostering self-generated turbulent reconnection in three dimensions (3D). In large-scale astrophysical and space systems, plasmoid instability likely initiates in the collisional regime but may transition into the collisionless regime as the fragmentation of the current sheet progresses toward kinetic scales. Hall magnetohydrodynamics (MHD) models are widely regarded as a simplified yet effective representation of the transition from collisional to collisionless reconnection. However, plasmoid instability in 2D Hall MHD simulations often leads to a single-X-line reconnection configuration, which significantly differs from fully kinetic particle-in-cell simulation results. This study shows that single-X-line reconnection is less likely to occur in 3D compared to 2D. Moreover, depending on the Lundquist number and the ratio between the system size and the kinetic scale, Hall MHD can also realize 3D self-generated turbulent reconnection. We analyze the features of the self-generated turbulent state, including the energy power spectra and the scale dependence of turbulent eddy anisotropy.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"284 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221859","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}
The turbulence mixing initiated by the Rayleigh–Taylor instability has been reported in a two-dimensional (2D) strongly coupled dusty plasma system using classical molecular dynamics simulation. The entire evolution cycle, including the initial equilibrium, the instability, turbulent mixing, and, finally, a new equilibrium through the thermalization process, has been demonstrated via the respective energy spectra. The fully developed spectrum follows the Bolgiano-Obukho k−11/5 scaling at smaller wavenumbers, a characteristic 2D buoyancy-driven turbulent flow feature. At higher wavenumbers, the energy spectrum E(k)∝k represents the thermalization of the system and is a characteristic feature of 2D Euler turbulence. At longer timescales, the system reflects the Kolmogorov scale of k−3. Moreover, strong coupling slows the turbulent mixing process, though the final state is a complete thermalized system. Our results also help us to understand the thermalization process in Yukawa fluids, other strongly coupled plasma families, and turbulent mixing in low Reynolds number fluids.
{"title":"Rayleigh–Taylor turbulence in strongly coupled dusty plasmas","authors":"Rauoof Wani, Mahendra Verma, Sanat Tiwari","doi":"10.1063/5.0216032","DOIUrl":"https://doi.org/10.1063/5.0216032","url":null,"abstract":"The turbulence mixing initiated by the Rayleigh–Taylor instability has been reported in a two-dimensional (2D) strongly coupled dusty plasma system using classical molecular dynamics simulation. The entire evolution cycle, including the initial equilibrium, the instability, turbulent mixing, and, finally, a new equilibrium through the thermalization process, has been demonstrated via the respective energy spectra. The fully developed spectrum follows the Bolgiano-Obukho k−11/5 scaling at smaller wavenumbers, a characteristic 2D buoyancy-driven turbulent flow feature. At higher wavenumbers, the energy spectrum E(k)∝k represents the thermalization of the system and is a characteristic feature of 2D Euler turbulence. At longer timescales, the system reflects the Kolmogorov scale of k−3. Moreover, strong coupling slows the turbulent mixing process, though the final state is a complete thermalized system. Our results also help us to understand the thermalization process in Yukawa fluids, other strongly coupled plasma families, and turbulent mixing in low Reynolds number fluids.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"6 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221861","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}
Ian E. Ochs, Mikhail E. Mlodik, Nathaniel J. Fisch
Synchrotron radiation losses are a significant cause of concern for high-temperature aneutronic fusion reactions such as proton–Boron 11. The fact that radiation losses occur primarily in the high-energy tail, where the radiation itself has a substantial impact on the electron distribution, necessitates a self-consistent approach to modeling the diffusion and drag induced by synchrotron absorption and emission. Furthermore, an accurate model must account for the fact that the radiation emission spectrum is momentum-dependent, and the plasma opacity is frequency-dependent. Here, we present a simple Fokker–Planck operator, built on a newly solved-for blackbody synchrotron diffusion operator, which captures all relevant features of the synchrotron radiation. Focusing on magnetic mirror fusion plasmas, we show that significant suppression of the electron distribution occurs for relativistic values of the perpendicular electron momentum, which therefore emit much less radiation than predicted under the assumption of a Maxwell–Jüttner distribution.
{"title":"Electron tail suppression and effective collisionality due to synchrotron emission and absorption in mildly relativistic plasmas","authors":"Ian E. Ochs, Mikhail E. Mlodik, Nathaniel J. Fisch","doi":"10.1063/5.0228464","DOIUrl":"https://doi.org/10.1063/5.0228464","url":null,"abstract":"Synchrotron radiation losses are a significant cause of concern for high-temperature aneutronic fusion reactions such as proton–Boron 11. The fact that radiation losses occur primarily in the high-energy tail, where the radiation itself has a substantial impact on the electron distribution, necessitates a self-consistent approach to modeling the diffusion and drag induced by synchrotron absorption and emission. Furthermore, an accurate model must account for the fact that the radiation emission spectrum is momentum-dependent, and the plasma opacity is frequency-dependent. Here, we present a simple Fokker–Planck operator, built on a newly solved-for blackbody synchrotron diffusion operator, which captures all relevant features of the synchrotron radiation. Focusing on magnetic mirror fusion plasmas, we show that significant suppression of the electron distribution occurs for relativistic values of the perpendicular electron momentum, which therefore emit much less radiation than predicted under the assumption of a Maxwell–Jüttner distribution.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"38 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221862","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}
This study investigates the causal relationships among azimuthal Fourier modes in linear plasma turbulence using multivariate time series models. We elucidate the dynamics of mode interactions in magnetized plasmas by employing the vector autoregressive model and Granger causality analysis. Our analysis, based on data from the plasma assembly for nonlinear turbulence analysis, reveals significant variations in causality with changing pressure conditions. Modes form weakly coupled clusters at lower pressures, while higher pressures lead to stronger coupling and larger clusters. The impulse response function further provides insights into the temporal propagation and nature of influences between modes. These findings enhance the understanding of spatial pattern formation in magnetized plasmas and offer a quantitative framework for analyzing plasma turbulence dynamics.
{"title":"Causal analysis among azimuthal Fourier modes in linear plasma based on multivariate time series models","authors":"F. Miwakeichi, M. Sasaki","doi":"10.1063/5.0223028","DOIUrl":"https://doi.org/10.1063/5.0223028","url":null,"abstract":"This study investigates the causal relationships among azimuthal Fourier modes in linear plasma turbulence using multivariate time series models. We elucidate the dynamics of mode interactions in magnetized plasmas by employing the vector autoregressive model and Granger causality analysis. Our analysis, based on data from the plasma assembly for nonlinear turbulence analysis, reveals significant variations in causality with changing pressure conditions. Modes form weakly coupled clusters at lower pressures, while higher pressures lead to stronger coupling and larger clusters. The impulse response function further provides insights into the temporal propagation and nature of influences between modes. These findings enhance the understanding of spatial pattern formation in magnetized plasmas and offer a quantitative framework for analyzing plasma turbulence dynamics.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"183 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221863","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}
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