Three-Way Serpentine Slow-Wave Structures with Stationary Inflection Point and Enhanced Interaction ImpedanceWe introduce two novel variants of the serpentine waveguide slow-wave structure (SWS), often utilized in millimeter-wave traveling-wave tubes (TWTs), with an enhanced interaction impedance. Using…Robert Marosi, Tarek Mealy, Alexander Figotin et al.·Mar 10, 2022SaveLearn
Action-angle coordinates for motion in a straight magnetic field with constant gradientThe motion of a charged particle in a straight magnetic field B = B(y)\, z with a constant perpendicular gradient is solved exactly in terms of elliptic functions and integrals. The…Alain J. Brizard·Mar 10, 2022SaveLearn
Modelling of saturated external MHD instabilities in tokamaks: a comparison of 3D free boundary equilibria and nonlinear stability calculations3D free boundary equilibrium computations have recently been used to model external kinks and edge harmonic oscillations (EHOs), comparing with linear MHD stability codes, and nonlinear analytic…Rohan Ramasamy, Guillermo Bustos Ramirez, Matthias Hoelzl et al.·Mar 9, 2022SaveLearn
Enhancing one-dimensional particle-in-cell simulations to self-consistently resolve instability-induced electron transport in Hall thrustersThe advent of high-power Hall thrusters and the increasing interest towards their use as a primary propulsion system for various missions have given a new boost to the efforts aiming at…Farbod Faraji, Maryam Reza, Aaron Knoll·Mar 9, 2022SaveLearn
Direct computation of magnetic surfaces in Boozer coordinates and coil optimization for quasi-symmetryWe propose a new method to compute magnetic surfaces that are parametrized in Boozer coordinates for vacuum magnetic fields. We also propose a measure for quasi-symmetry on the computed surfaces and…Andrew Giuliani, Florian Wechsung, Matt Landreman et al.·Mar 7, 2022SaveLearn
Dimits transition in three-dimensional ion-temperature-gradient turbulenceWe extend our previous work on the 2D Dimits transition in ion-scale turbulence (Ivanov et al. 2020) to include variations along the magnetic field. We consider a three-field fluid model for the…Plamen G. Ivanov, Alexander A. Schekochihin, William Dorland·Mar 5, 2022SaveLearn
Comment on "Comparison of six simulation codes for positive streamers in air"(Plasma Sources Sci. Technol. 27 (2018) 095002)Recently, a comparison of six codes for streamer discharge simulations were performed in [1]. In this comment, we discuss about the big differences between the results obtained by the different codes…Xiang Li·Mar 4, 2022SaveLearn
Research Opportunities in Plasma AstrophysicsMajor scientific questions and research opportunities are described on 10 unprioritized plasma astrophysics topics: (1) magnetic reconnection, (2) collisionless shocks and particle acceleration, (3)…Stuart Bale, Amitava Bhattacharjee, Fausto Cattaneo et al.·Mar 4, 2022SaveLearn
The dispersion and propagation of topological Langmuir-cyclotron waves in cold magnetized plasmasTopological Langmuir-Cyclotron Wave (TLCW) is a recently identified topological surface excitation in magnetized plasmas. We show that TLCW originates from the topological phase transition at the…Yichen Fu, Hong Qin·Mar 3, 2022SaveLearn
Understanding Vacuum Arcs and Gradient LimitsAlthough a general model of vacuum arcs and gradient limits would be widely useful, roughly 120 years after the first good experimental data on these arcs, this important field continues to be…J. Norem, Z. insepov, A. Hassanein·Mar 3, 2022SaveLearn
Different configurations of transferred atmospheric pressure plasma jet and their application to polymer treatmentThe employment of atmospheric pressure plasma jets (APPJs) in a large sort of applications is limited by the adversities related to the size of the treated area and the difficulty to reach the…Fellype do Nascimento, Konstantin Georgiev Kostov, Antje Quade et al.·Mar 3, 2022SaveLearn
Excitation of electrostatic solitary waves and surface waves in ion beam neutralization processUnusually long electrostatic solitary waves (ESWs) are discovered in 2D and 3D Particle-in-Cell studies of the process of ion beam neutralization by electron emission from filaments. These ESWs are…Nakul Nuwal, Igor D. Kaganovich, Deborah A. Levin·Mar 3, 2022SaveLearn
Kinetic modeling of three-dimensional electrostatic-solitary and surface waves in beam neutralizationThis work studies the fundamental plasma processes involved in the neutralization of an ion beam's space-charge by electrons emitted by a filament using Particle-in-Cell simulations. While…Nakul Nuwal, Deborah A. Levin, Igor D. Kaganovich·Mar 3, 2022SaveLearn
Multi-scale analysis of global electromagnetic instabilities in ITER Pre-Fusion-Power Operation plasmasGlobal electromagnetic gyrokinetic simulations are performed with the Particle-in-Cell code ORB5 for an ITER Pre-Fusion-Power-Operation (PFPO) plasma scenario, with half-field (2.65 T) and…T. Hayward-Schneider, Ph. Lauber, A. Bottino et al.·Mar 3, 2022SaveLearn
Analytical expressions for thermophysical properties of solid and liquid beryllium relevant for fusion applicationsThe status of the literature is reviewed for thermophysical properties of pure polycrystalline solid and liquid beryllium which constitute input for the modelling of intense plasma-surface…P. Tolias·Mar 2, 2022SaveLearn
Local cascade and dissipation in incompressible Hall magnetohydrodynamic turbulence: the Coarse-Graining approachWe derive the coarse-graining (CG) equations of incompressible Hall Magnetohydrodynamics (HMHD) turbulence to investigate the local (in space) energy cascade rate as a function of the filtering…Davide Manzini, Fouad Sahraoui, Francesco Califano et al.·Mar 2, 2022SaveLearn
Transfer Learning of High-Fidelity Opacity Spectra in Autoencoders and Surrogate ModelsSimulations of high energy density physics are expensive, largely in part for the need to produce non-local thermodynamic equilibrium opacities. High-fidelity spectra may reveal new physics in the…Michael D. Vander Wal, Ryan G. McClarren, Kelli D. Humbird·Mar 2, 2022SaveLearn
Three-Dimensional Inhomogeneity of Electron-Temperature-Gradient Turbulence in the Edge of Tokamak PlasmasNonlinear multiscale gyrokinetic simulations of a Joint European Torus edge pedestal are used to show that electron-temperature-gradient (ETG) turbulence has a rich three-dimensional structure,…J. F. Parisi, F. I. Parra, C. M. Roach et al.·Mar 2, 2022SaveLearn
3D particle simulations of positive air-methane streamers for combustionStreamer discharges can be used as a primary source of reactive species for plasma-assisted combustion. In this research we investigate positive streamers in a stoichiometric air-methane mixture at 1…Dennis Bouwman, Jannis Teunissen, Ute Ebert·Mar 1, 2022SaveLearn
Gyrokinetic modelling of the Alfvén mode activity in ASDEX Upgrade with an isotropic slowing-down fast-particle distributionIn the present paper, the evolution of the Alfvén modes is studied in a realistic ASDEX Upgrade equilibrium by analysing the results of simulations with the global, electromagnetic, gyrokinetic…Francesco Vannini, Alessandro Biancalani, Alberto Bottino et al.·Mar 1, 2022SaveLearn
Evaluation of direct inversion of proton radiographs in the context of cylindrical implosionsDirect inversion of deflectometry data, such as proton radiographs and shadowgraphs, is a well-posed problem with a unique solution for the transverse deflection of each particle or ray if their…J. R. Davies, P. V. Heuer·Mar 1, 2022SaveLearn
Mode transition (α-γ) and hysteresis in microwave-driven low-temperature plasmasWe discovered a hysteresis in a microwave-driven low-pressure argon plasma during gas pressure change across the transition region between α and γ discharge modes. The hysteresis is manifested in…Kyungtae Kim, Woojin Nam, Jimo Lee et al.·Mar 1, 2022SaveLearn
Chandrasekhar-Kendall-Woltjer-Taylor state in a resistive plasmaWe give a criterion for the Chandrasekhar-Kendall-Woltjer-Taylor (CKWT) state in a resistive plasma. We find that the lowest momentum (longest wavelength) of the initial helicity amplitudes of…Ze-Yu Zhai, Yang-Guang Yang, Xiao-Liang Xia et al.·Mar 1, 2022SaveLearn
Induced Current Due to Electromagnetic Shock Produced by Charge Impact on a Conducting SurfaceThis paper compares the transient induced current due to the electromagnetic shock produced by a charged particle impacting a perfectly conducting plate, with the classical, quasi-static induced…D. Li, P. Wong, D. Chernin et al.·Mar 1, 2022SaveLearn
Neural net modeling of equilibria in NSTX-UNeural networks (NNs) offer a path towards synthesizing and interpreting data on faster timescales than traditional physics-informed computational models. In this work we develop two neural networks…J. T. Wai, M. D. Boyer, E. Kolemen·Feb 28, 2022SaveLearn