Physics of Plasmas最新文献_第2页

High-yield implosion modeling using the Frustraum: Assessing and controlling the formation of polar jets and enhancing implosion performance with applied magnetization 使用 Frustraum 进行高产能内爆建模：评估和控制极地喷流的形成，利用外加磁化提高内爆性能

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-17 DOI: 10.1063/5.0215638

D. D.-M. Ho, P. A. Amendt, K. L. Baker, O. L. Landen, J. D. Lindl, M. M. Marinak, H. Sio, A. L. Velikovich, G. B. Zimmerman, A. L. Kritcher, E. L. Dewald, D. A. Mariscal, J. D. Salmonson, C. R. Weber

{"title":"High-yield implosion modeling using the Frustraum: Assessing and controlling the formation of polar jets and enhancing implosion performance with applied magnetization","authors":"D. D.-M. Ho, P. A. Amendt, K. L. Baker, O. L. Landen, J. D. Lindl, M. M. Marinak, H. Sio, A. L. Velikovich, G. B. Zimmerman, A. L. Kritcher, E. L. Dewald, D. A. Mariscal, J. D. Salmonson, C. R. Weber","doi":"10.1063/5.0215638","DOIUrl":"https://doi.org/10.1063/5.0215638","url":null,"abstract":"Frustraums have a higher laser-to-capsule x-ray radiation coupling efficiency and can accommodate a large capsule, thus potentially generating a higher yield with less laser energy than cylindrical Hohlraums for a given Hohlraum volume [Amendt et al., Phys. Plasmas 26, 082707 (2019]. Frustraums are expected to have less m = 4 azimuthal asymmetries arising from the intrinsic inner-laser-beam geometry on the National Ignition Facility. An experimental campaign at Lawrence Livermore National Laboratory to demonstrate the high-coupling efficiency and radiation symmetry tuning of the Frustraum has been under way since 2021. Simulations benchmarked against experimental data show that implosions using Frustraums can achieve more yield with higher ignition margins than cylindrical Hohlraums using the same laser energy. Hydrodynamic jets in capsules along the Hohlraum axis, driven by radiation-flux asymmetries in a Hohlraum with a gold liner on a depleted uranium (DU) wall, are present around stagnation, and these “polar” jets can cause severe yield degradation. The early-time Legendre mode P4&lt;0 radiation-flux asymmetry is a leading cause of these jets, which can be reduced by using an unlined DU Hohlraum because the shape of the shell is predicted to be more prolate. Magnetization can increase the implosion robustness and reduce the required hotspot ρR for ignition; therefore, magnetizing the Frustraum can maintain the same yield while reducing the required laser energy or increase the yield using the same laser energy—all under the constraint that the ignition margin is preserved. Reducing polar jets is particularly important for magnetized implosions because of the intrinsic toroidal hotspot ion temperature topology.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"22 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259331","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

Two-plasmon-decay instability in the non-eigenmode regime in laser–plasma interaction 激光-等离子体相互作用非特征模式下的双质子衰减不稳定性

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-17 DOI: 10.1063/5.0206054

Charles F. Wu, Yao Zhao, Hang-Hang Ma, Xu-Yan Jiang, Xiao-Feng Li, Su-Ming Weng, Min Chen, Zheng-Ming Sheng

引用次数: 0

The long road to ignition: An eyewitness account 漫长的点火之路目击者的叙述

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-17 DOI: 10.1063/5.0221005

Mordecai D. Rosen

{"title":"The long road to ignition: An eyewitness account","authors":"Mordecai D. Rosen","doi":"10.1063/5.0221005","DOIUrl":"https://doi.org/10.1063/5.0221005","url":null,"abstract":"This paper reviews the many twists and turns in the long journey that culminated in ignition in late 2022 using the laser heated indirect-drive approach to imploding DT filled targets at the National Ignition Facility (NIF), located at the Lawrence Livermore National Laboratory (LLNL). We describe the early origins of the Laser Program at LLNL and key developments such as the paradigm shifting birth of high energy density physics (HEDP) studies with lasers, changes in choice of laser wavelength, and the development of key diagnostics and computer codes. Fulfilling the requirements of the multi-faceted Nova Technical Contract was a necessary condition for the approval of the NIF, but more importantly, the end of the Cold War and the cessation of nuclear testing were key catalysts in that approval, along with the ready-and-waiting field of HEDP. The inherent flexibility of the field of laser driven inertial confinement fusion played a fundamental role in achieving success at the NIF. We describe how the ultimately successful ignition target design evolved from the original “point design” target, through the lessons of experiment. All key aspects of that original design changed: The capsule's materials and size were changed; the hohlraum's materials, size, laser entrance hole size, and gas fills were also all changed, as were the laser pulse shapes that go along with all those changes. The philosophy to globally optimize performance for stability (by raising the adiabat and thus lowering the implosion convergence) was also key, as was progress in target fabrication, and in increasing NIF's energy output. The persistence of the research staff and the steadfast backing of our supporters were also necessary elements in this success. We gratefully acknowledge seven decades of researcher endeavors and four decades of the dedicated efforts of many hundreds of personnel across the globe who have participated in NIF construction, operation, target fabrication, diagnostic, and theoretical advances that have culminated in ignition.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"29 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259330","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

Symmetry and structure in the “Generalized Plasma Focus problem” 广义等离子体焦点问题 "中的对称性和结构

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-17 DOI: 10.1063/5.0225122

S. K. H. Auluck

{"title":"Symmetry and structure in the “Generalized Plasma Focus problem”","authors":"S. K. H. Auluck","doi":"10.1063/5.0225122","DOIUrl":"https://doi.org/10.1063/5.0225122","url":null,"abstract":"The “Generalized Plasma Focus problem” refers to a generic class of plasma propagation phenomena that share many features of a dense plasma focus device. Its recent theoretical development has been shown to predict some features of the pinch phase in PF-1000 and POSEIDON. The theory attempts to decompose the plasma propagation problem into two weakly interdependent subproblems. This is achieved by expressing every physical variable of an applicable continuum model of the plasma as the product of a scaling parameter, which contains device-related information and represents its numerical magnitude, and a scaled variable that is devoid of device-related information, is of order unity, and represents the spatiotemporal structure of that variable. The first subproblem seeks a traveling surface of revolution whose local normal velocity equals the scaling parameter for velocity and is aligned with the magnetic force density. Spatiotemporal distributions of all the scaled variables must move along with this reference surface by definition. This paper explores the resulting scaling theory and its symmetry properties. A new coordinate transformation results in a formula for the spatiotemporal distribution of the magnetic field of the curved and non-steady plasma sheath. New insights into the snowplow effect are obtained. A current sheath with a rear boundary exists only when the current is decreasing and only when the current carrying plasma is less dense than the fill gas. The current sheath thickness is the same for small and large devices. The geomagnetic flux compression problem has an exact solution.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"10 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259329","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

Time-dependent probability density functions and information geometry in a stochastic prey–predator model of fusion plasmas 聚变等离子体随机捕食者-捕食者模型中与时间相关的概率密度函数和信息几何学

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-11 DOI: 10.1063/5.0193622

Patrick Fuller, Eun-jin Kim, Rainer Hollerbach, Bogdan Hnat

引用次数: 0

Modeling of nonequilibrium effects in a compressible plasma based on the lattice Boltzmann method 基于晶格玻尔兹曼法的可压缩等离子体非平衡效应建模

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-10 DOI: 10.1063/5.0211465

Haoyu Huang, Ke Jin, Kai Li, Xiaojing Zheng

{"title":"Modeling of nonequilibrium effects in a compressible plasma based on the lattice Boltzmann method","authors":"Haoyu Huang, Ke Jin, Kai Li, Xiaojing Zheng","doi":"10.1063/5.0211465","DOIUrl":"https://doi.org/10.1063/5.0211465","url":null,"abstract":"A magnetohydrodynamic lattice Boltzmann method (MHD-LBM) model for a 2D compressible plasma based on the finite volume scheme is established. The double distribution D2Q17 discrete velocities are used to simulate the fluid field. The hyperbolic Maxwell equations, which satisfy the elliptic constraints of Maxwell's equations and the constraint of charge conservation, are used to simulate the electromagnetic field. The flow field and electromagnetic field are coupled to simulate a compressible plasma through the electromagnetic force and magnetic induction equations. Four typical cases, the Taylor vortex flow, strong blast, Orszag–Tang vortex, and one-dimensional Riemann problems, are simulated to validate the MHD-LBM model for a compressible plasma. It is found that shock waves widely exist in a compressible plasma, and strong nonequilibrium effects exist around each shock wave. The quantitative simulation for the Brio–Wu problem demonstrates that this model can easily obtain the physical characteristics of nonequilibrium effects at sharp interfaces (shock waves and detonation waves). The magnetic fields can affect the magnitudes to which the system deviates from its equilibrium state. The viscosity can increase the magnitudes to which the system deviates from its equilibrium state. Compared with existing compressible MHD, these results for nonequilibrium effects can provide mesoscopic physical insights into the flow mechanism of a shock wave in a supersonic plasma.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"40 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221797","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

Theory of phase-space hydrodynamics of electron and ion holes in collisionless plasmas 无碰撞等离子体中电子和离子空穴的相空间流体力学理论

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0216144

Allen Lobo, Vinod Kumar Sayal

{"title":"Theory of phase-space hydrodynamics of electron and ion holes in collisionless plasmas","authors":"Allen Lobo, Vinod Kumar Sayal","doi":"10.1063/5.0216144","DOIUrl":"https://doi.org/10.1063/5.0216144","url":null,"abstract":"Phase-space holes are well-known Bernstein–Greene–Kruskal (B.G.K.) modes and are formed by particle-trapping in solitary potential waveforms. They exhibit orbital particle trajectories in the phase-space, due to which they are also referred to as phase-space vortices. In this article, we develop the theory of phase-space hydrodynamics for electron and ion phase-space in collisionless plasmas. The analogy between ordinary two-dimensional fluids and 1D−1V phase-space has been explored by introducing a momentum equation and a phase-space vorticity field, which enable the fluid-like analyses of the plasma phase-space. The developed kinetic-hydrodynamic equations are then employed to address the vortical nature of phase-space holes by exploring their fluid-analogous vortex-like characteristics, an identification technique of phase-space vortices, an exact derivation of the Schamel-df equations, and a measurable definition of the particle-trapping β parameter. This article introduces a new technique to the study of phase-space holes which focuses on the fluid-analogous vortical nature of the phase-space holes and prevents the need for an initial assumption of the trapped and free particle phase-space densities, thus presenting itself as a precursor to the Schamel-pseudopotential method.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"8 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221805","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

EFIT-Prime: Probabilistic and physics-constrained reduced-order neural network model for equilibrium reconstruction in DIII-D EFIT-Prime：用于 DIII-D 平衡重建的概率和物理约束降阶神经网络模型

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0213609

S. Madireddy, C. Akçay, S. E. Kruger, T. Bechtel Amara, X. Sun, J. McClenaghan, J. Koo, A. Samaddar, Y. Liu, P. Balaprakash, L. L. Lao

{"title":"EFIT-Prime: Probabilistic and physics-constrained reduced-order neural network model for equilibrium reconstruction in DIII-D","authors":"S. Madireddy, C. Akçay, S. E. Kruger, T. Bechtel Amara, X. Sun, J. McClenaghan, J. Koo, A. Samaddar, Y. Liu, P. Balaprakash, L. L. Lao","doi":"10.1063/5.0213609","DOIUrl":"https://doi.org/10.1063/5.0213609","url":null,"abstract":"We introduce EFIT-Prime, a novel machine learning surrogate model for EFIT (Equilibrium FIT) that integrates probabilistic and physics-informed methodologies to overcome typical limitations associated with deterministic and ad hoc neural network architectures. EFIT-Prime utilizes a neural architecture search-based deep ensemble for robust uncertainty quantification, providing scalable and efficient neural architectures that comprehensively quantify both data and model uncertainties. Physically informed by the Grad–Shafranov equation, EFIT-Prime applies a constraint on the current density Jtor and a smoothness constraint on the first derivative of the poloidal flux, ensuring physically plausible solutions. Furthermore, the spatial location of the diagnostics is explicitly incorporated in the inputs to account for their spatial correlation. Extensive evaluations demonstrate EFIT-Prime's accuracy and robustness across diverse scenarios, most notably showing good generalization on negative-triangularity discharges that were excluded from training. Timing studies indicate an ensemble inference time of 15 ms for predicting a new equilibrium, offering the possibility of plasma control in real-time, if the model is optimized for speed.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"5 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221809","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

Sheet model description of spatiotemporal evolution of upper-hybrid oscillations in an inhomogeneous magnetic field 非均质磁场中上混合振荡时空演变的片状模型描述

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0220066

Nidhi Rathee, Someswar Dutta, R. Srinivasan, Sudip Sengupta

{"title":"Sheet model description of spatiotemporal evolution of upper-hybrid oscillations in an inhomogeneous magnetic field","authors":"Nidhi Rathee, Someswar Dutta, R. Srinivasan, Sudip Sengupta","doi":"10.1063/5.0220066","DOIUrl":"https://doi.org/10.1063/5.0220066","url":null,"abstract":"Spatiotemporal evolution of large amplitude upper-hybrid oscillations in a cold homogeneous plasma in the presence of an inhomogeneous magnetic field is studied analytically and numerically using the Dawson sheet model [J. Dawson, Phys. Fluids 5, 445–459 (1962)]. It is observed that the inhomogeneity in magnetic field, which causes the upper-hybrid frequency to acquire a spatial dependence, results in phase mixing and subsequent breaking of the upper-hybrid oscillations at arbitrarily low amplitudes. This result is in sharp contrast to the usual upper-hybrid oscillations in a homogeneous magnetic field, where the oscillations break within a fraction of a period when the amplitude exceeds a certain critical value [R. C. Davidson, Methods in Nonlinear Plasma Theory (Academic, New York, 1972)]. Our perturbative calculations show that the phase mixing (wave breaking) time scales inversely with the amplitude of magnetic field inhomogeneity (Δ) and amplitude of imposed density perturbation (δ) and scales directly with the ratio of magnetic field inhomogeneity scale length to imposed density perturbation scale length [(α/kL)−1] as ωpeτmix∼(1+β2)3/2kL/(β2δΔα), where β is the ratio of electron cyclotron frequency to electron plasma frequency. Further phase mixing time measured in simulations, performed using a 1–1/2 D code based on the Dawson sheet model [J. Dawson, Phys. Fluids 5, 445–459 (1962)], shows good agreement with the above-mentioned scaling. This result may be of relevance to plasma based particle acceleration experiments in the presence of a transverse inhomogeneous magnetic field.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221803","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

Three-wave coupling observed between a shear Alfvén wave and a kink-unstable magnetic flux rope 在剪切阿尔弗波和不稳定磁通绳之间观测到的三波耦合

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0217895

S. Vincena, S. K. P. Tripathi, W. Gekelman, P. Pribyl

{"title":"Three-wave coupling observed between a shear Alfvén wave and a kink-unstable magnetic flux rope","authors":"S. Vincena, S. K. P. Tripathi, W. Gekelman, P. Pribyl","doi":"10.1063/5.0217895","DOIUrl":"https://doi.org/10.1063/5.0217895","url":null,"abstract":"Results from a laboratory experiment are presented in which, for the first time, a shear Alfvén wave is launched using an antenna in a current-carrying plasma column that is tailored to be either stable or unstable to the kink oscillation. As the plasma is driven kink unstable, the frequency power spectrum of the Alfvén wave evolves from a single peak to a peak with multiple sidebands separated by integer multiples of the kink frequency. The main sidebands (one on either side of the launched wave peak in the power spectrum) are analyzed using azimuthal wavenumber matching, perpendicular and parallel wavenumber decomposition, and bispectral time series analysis. The dispersion relation and three-wave matching conditions are satisfied, given each sideband is a propagating Alfvén wave that results from the interaction of the pump Alfvén wave and the co-propagating component of a half-wavelength, standing kink mode. The interaction is shown to generate smaller perpendicular wavelength Alfvén waves that drive energy transport to scales that will approach the dissipation scale of k⊥ρs=1, with k⊥ being the perpendicular wavenumber and ρs being the ion gyroradius at the electron temperature.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"3 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221804","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