total 6720took 0.29s

From quantum to classical modelling of radiation reaction: a focus on the radiation spectrumFeb 08 2018Soon available multi petawatt ultra-high-intensity (UHI) lasers will allow us to probe high-amplitude electromagnetic fields interacting with either ultra-relativistic electron beams or hot plasmas in the so-called moderately quantum regime. The correct ... More

Swarm parameter measurement in hydrogen, considering secondary photonic electron emissionFeb 08 2018Discharges in hydrogen at pressures above $1\,$kPa and a reduced electric field of $E/N=100-200\,$Td show a characteristic current oscillation in Pulsed Townsend experiments. This is explained by secondary emission of electrons from the photo-cathode: ... More

Longitudinal structure of the photospheric magnetic field in the Carrington systemFeb 08 2018The observations of the Sun have been performed over the years, even centuries- Whether are there active longitudes? If yes how stable are they? One of the first The Wilcox Solar Observatory data taken over three cycles N 21, N 22, N 23 have been used ... More

Rotation of the photospheric magnetic field through solar cycles 21, 22, 23Feb 07 2018Rotation of the large scale solar magnetic field has a great importance for the understanding of solar dynamic, for the search of longitidinal structure and for the study of solar-terrestrial relations. 30-year long observations taken at the Wilcox Solar ... More

Latitudinal structure and dynamic of the photospheric magnetic fieldFeb 07 2018Analysis of the structure and dynamics of the magnetic field of the Sun is fundamental for understanding of the origin of solar activity and variability as well as for the study of solar-terrestrial relations. Observations of the large scale magnetic ... More

Single and multiple pin(s)-to-liquid discharges: connecting self-organization patterns and ROS production in liquids for plasma agronomy applicationFeb 06 2018Pin-to-liquid discharges are investigated for the activation of liquids dedicated to agriculture applications. They are characterized through their electrical and optical properties, with a particular attention paid to their filaments and self-organized ... More

Synthesis and/or grafting of noble metal nanoparticles by microplasma and by atmospheric plasma torchFeb 06 2018Plasmas at atmospheric pressure are presented as a simple, fast, and versatile tool for the synthesis or/and the grafting of noble metallic NPs (Au, Pt) on substrates. In this study, noble metal NPs are generated either by the reduction of a gold salt ... More

Magnetohydrodynamic Turbulence in the Plasmoid-Mediated RegimeFeb 06 2018Magnetohydrodynamic turbulence and magnetic reconnection are ubiquitous in astrophysical environments. In most situations, these processes do not occur in isolation, but interact with each other. This renders a comprehensive theory of these processes ... More

A fluid-kinetic framework for self-consistent runaway-electron simulationsFeb 06 2018Feb 08 2018The problem of self-consistently coupling kinetic runaway-electron physics to the macroscopic evolution of the plasma is addressed by dividing the electron population into a bulk and a tail. A probabilistic closure is adopted to determine the coupling ... More

Ultrafast Imaging of Laser Driven Shock Waves using Betatron X-rays from a Laser Wakefield AcceleratorFeb 06 2018Betatron radiation from laser wakefield accelerators is an ultrashort pulsed source of hard, synchrotron-like x-ray radiation. It emanates from a centimetre scale plasma accelerator producing GeV level electron beams. In recent years betatron radiation ... More

Microscopic modeling of gas-surface scattering. II. Application to argon atom adsorption on a platinum (111) surfaceFeb 06 2018A new combination of first principle molecular dynamics (MD) simulations with a rate equation model presented in the preceding paper (paper I) is applied to analyze in detail the scattering of argon atoms from a platinum (111) surface. The combined model ... More

Synthesis of Membrane-Electrode Assembly for Fuel Cells by Means of (Sub)-Atmospheric Plasma ProcessesFeb 06 2018An easy procedure to build up membrane-electrode assemblies for applications dedicated to miniaturized PEMFC using H2 or CH3OH by a two-steps atmospheric plasma process is reported. Firstly, catalyst nanoparticles are grafted on carbon substrates by spraying ... More

Ionization injection in a laser wakefield accelerator subject to a transverse magnetic fieldFeb 06 2018The effect of an external transverse magnetic field on ionization injection of electrons in a laser wakefield accelerator (LWFA) is investigated by theoretical analysis and particle-in-cell simulations. On application of a few tens of Tesla magnetic field, ... More

Effect of differential cross section in Breit-Wheeler pair beamingFeb 06 2018The pair beaming in the Breit-Wheeler (BW) process is investigated. We examine the effect of the BW differential cross section on pair angular and energy distributions. Although, this study is relevant for laser induced intense gamma-ray source collisions ... More

Losses in plasmonics: from mitigating energy dissipation to embracing loss-enabled functionalitiesFeb 05 2018Unlike conventional optics, plasmonics enables unrivalled concentration of optical energy well beyond the diffraction limit of light. However, a significant part of this energy is dissipated as heat. Plasmonic losses present a major hurdle in the development ... More

General features of experiments on the dynamics of laser-driven electron-positron beamsFeb 05 2018The experimental study of the dynamics of neutral electron-positron beams is an emerging area of research, enabled by the recent results on the generation of this exotic state of matter in the laboratory. Electron-positron beams and plasmas are believed ... More

Validating Continuum Lowering Models via Multi-Wavelength Measurements of Integrated X-ray EmissionFeb 05 2018X-ray emission spectroscopy is a well-established technique used to study continuum lowering in dense plasmas. It relies on accurate atomic physics models to robustly reproduce high-resolution emission spectra, and depends on our ability to identify spectroscopic ... More

Positivity-preserving scheme for two-dimensional advection-diffusion equations including mixed derivativesFeb 03 2018In this work, we propose a positivity-preserving scheme for solving two-dimensional advection-diffusion equations including mixed derivative terms, in order to improve the accuracy of lower-order methods. The solution to these equations, in the absence ... More

A low-frequency variational model for energetic particle effects in the pressure-coupling schemeFeb 03 2018Energetic particle effects in magnetic confinement fusion devices are commonly studied by hybrid kinetic-fluid simulation codes whose underlying continuum evolution equations often lack the correct energy balance. While two different kinetic-fluid coupling ... More

Modelling of pulse train generation for resonant laser wakefield acceleration using a delay maskFeb 02 2018A new method for the generation of a train of pulses from a single high-energy, ultra short pulse is presented, suited for Resonant Multi-Pulse Ionization injection. The method is based on different transverse portion of the pulse being delayed by a "mask" ... More

Investigation of the dynamics of ionization induced injected electrons under the influence of beam loading effectsFeb 01 2018In laser-driven wakefield, ionization induced injection is an efficient way to inject electrons in the plasma wave. A detailed study on the beam dynamics under the influence of beam loading effects, which can be controlled by the concentration of nitrogen ... More

Magnetothermodynamics: Measurements of the thermodynamic properties in a relaxed magnetohydrodynamic plasmaJan 31 2018We have explored the thermodynamics of compressed magnetized plasmas in laboratory experiments and we call these studies "magnetothermodynamics". The experiments are carried out in the Swarthmore Spheromak eXperiment device. In this device, a magnetized ... More

Global gyrokinetic simulations of intrinsic rotation in ASDEX Upgrade Ohmic L-mode plasmasJan 31 2018Non-linear, radially global, turbulence simulations of ASDEX Upgrade (AUG) plasmas are performed and the nonlinear generated intrinsic flow shows agreement with the intrinsic flow gradients measured in the core of Ohmic L-mode plasmas at nominal parameters. ... More

Regularized $κ$-distributions with non-diverging momentsJan 31 2018Feb 06 2018For various plasma applications the so-called (non-relativistic) $\kappa$-distribution is widely used to reproduce and interpret the suprathermal particle populations exhibiting a power-law distribution in velocity or energy. Despite its reputation the ... More

Laser acceleration of highly energetic carbon ions using a double-layer target composed of slightly underdense plasma and ultrathin foilJan 31 2018We report the experimental generation of highly energetic carbon ions up to 48 MeV per nucleon by shooting double-layer targets composed of well-controlled slightly underdense plasma (SUP) and ultrathin foils with ultra-intense femtosecond laser pulses. ... More

Helically symmetric extended MHD: Hamiltonian formulation and equilibrium variational principlesJan 30 2018Hamiltonian extended MHD (XMHD) dynamics is restricted to respect helical symmetry by reducing the Poisson bracket for 3D dynamics to a helically symmetric one, as an extension of the previous study for translationally symmetric XMHD [D. A. Kaltsas et ... More

X-ray phase-contrast imaging for laser-induced shock wavesJan 30 2018X-ray phase-contrast imaging (XPCI) is a versatile technique with wide-ranging applications, particularly in the fields of biology and medicine. Where X-ray absorption radiography requires high density ratios for effective imaging, XPCI is more sensitive ... More

Oscillatory relaxation of zonal flows in a multi-species stellarator plasmaJan 29 2018The low frequency oscillatory relaxation of zonal potential perturbations is studied numerically in the TJ-II stellarator (where it was experimentally detected for the first time). It is studied in full global gyrokinetic simulations of multi-species ... More

Mean-field theory of differential rotation in density stratified turbulent convectionJan 26 2018A mean-field theory of differential rotation in a density stratified turbulent convection has been developed. This theory is based on a combined effect of the turbulent heat flux and anisotropy of turbulent convection increasing with the rate of rotation ... More

Fully kinetic large scale simulations of the collisionless Magnetorotational instabilityJan 26 2018We present two-dimensional particle-in-cell (PIC) simulations of the fully kinetic collisionless magnetorotational instability (MRI) in weakly magnetized (high $\beta$) pair plasma. The central result of this numerical analysis is the emergence of a self-induced ... More

Observation of ultrafast solid-density plasma dynamics using femtosecond X-ray pulses from a free-electron laserJan 25 2018The complex physics of the interaction between short pulse high intensity lasers and solids is so far hardly accessible by experiments. As a result of missing experimental capabilities to probe the complex electron dynamics and competing instabilities, ... More

Temperature gradient driven heat flux closure in fluid simulations of collisionless reconnectionJan 23 2018Recent efforts to include kinetic effects in fluid simulations of plasmas have been very promising. Concerning collisionless magnetic reconnection, it has been found before that damping of the pressure tensor to isotropy leads to good agreement with kinetic ... More

Modulated dust-acoustic wave packets in an opposite polarity dusty plasma systemJan 23 2018The nonlinear propagation of the dust-acoustic bright and dark envelope solitons in an opposite polarity dusty plasma system (composed of non-extensive $q$-distributed electrons, isothermal ions, and positively as well as negatively charged warm dust) ... More

Can Hall effect trigger Kelvin-Helmholtz instability in sub-Alfvenic flows?Jan 22 2018In the Hall magnetohydrodynamics, the onset condition of the Kelvin Helmholtz instability is solely determined by the Hall effect and is independent of the nature of shear flows. In addition, the physical mechanism behind the super and sub Alfvenic flows ... More

The Role of Proton-Cyclotron Resonance as a Dissipation Mechanism in Solar Wind Turbulence: A Statistical Study at Ion-Kinetic ScalesJan 22 2018We use magnetic field and particle data from the WIND spacecraft MFI and SWE instruments to study the nature of the solar wind turbulence at ion-kinetic scales. We begin by making the first in-flight measurement of the MFI 'noise-floor' using tail-lobe ... More

The effect of interference on the trident process in a constant crossed fieldJan 22 2018We perform a complete calculation of electron-seeded pair-creation (the trident process) in a constant crossed electromagnetic background. Unlike earlier treatments, we include the interference between exchange diagrams. We find this exchange interference ... More

Degenerate Variational Integrators for Magnetic Field Line Flow and Guiding Center TrajectoriesJan 22 2018Symplectic integrators offer many advantages for the numerical solution of Hamiltonian differential equations, including bounded energy error and the preservation of invariant sets. Two of the central Hamiltonian systems encountered in plasma physics ... More

Charge transfer in H + He$^+$ and H$^+$ + He collisions in excited statesJan 21 2018We present a theoretical study of charge transfer in collisions of excited ($n=2,3$) hydrogen atoms with He$^+$ and in collisions of excited ($n=2,3$) helium atoms with H$^+$, extending the results of Phys. Rev. A 82 012708 (2010). A combination of quantum-mechanical ... More

Laser guided ionic windJan 21 2018We report on a method to experimentally generate ionic wind by coupling an external high voltage electric field with an intense femtosecond laser induced air plasma filament. The measured ionic wind velocity could be as strong as >4 m/s. It could be optimized ... More

Dust ion acoustic solitary structures at the acoustic speed in presence of nonthermal electrons and isothermal positronsJan 20 2018The Sagdeev pseudo-potential technique and the analytic theory developed by Das et al. [J. Plasma Phys. 78, 565 (2012)] have been used to investigate the dust ion acoustic solitary structures at the acoustic speed in a collisionless unmagnetized dusty ... More

Strategies for Advantageous Differential Transport of Ions in Magnetic Fusion DevicesJan 19 2018In a variety of magnetized plasma geometries, it has long been known that highly charged impurities tend to accumulate in regions of higher density. Here, we examine how this "collisional pinch" changes in the presence of additional forces, such as might ... More

Onset of fast "ideal" tearing in thin current sheets: dependence on the equilibrium current profileJan 19 2018In this paper we study the scaling relations for the triggering of the fast, or "ideal", tearing instability starting from equilibrium configurations relevant to astrophysical as well as laboratory plasmas that differ from the simple Harris current sheet ... More

A Laser-Plasma Positron Accelerator using Particle-Shower Plasma-Wave interactionsJan 19 2018An all-optical laser-plasma positron accelerator is introduced and modeled using the interaction of laser-driven particle-showers with laser-driven electron plasma-waves. The principle uncovered here shows the trapping and acceleration of positrons that ... More

Axion-plasmon polaritons in strongly magnetized plasmasJan 18 2018Axions are hypothetical particles related to the violation of the charge-parity symmetry, being the most prone candidates for dark matter. Multiple attempts to prove their existence are currently performed in different physical systems. Here, we anticipate ... More

Collisionless Magnetic Reconnection in Curved Spacetime and the Effect of Black Hole RotationJan 18 2018Magnetic reconnection in curved spacetime is studied by adopting a general relativistic magnetohydrodynamic model that retains collisionless effects for both electron-ion and pair plasmas. A simple generalization of the standard Sweet-Parker model allows ... More

Multidimensional effects on proton acceleration using high-power intense laser pulsesJan 18 2018Dimensional effects in particle-in-cell (PIC) simulation of target normal sheath acceleration (TNSA) of protons are considered. As the spatial divergence of the laser-accelerated hot sheath electrons and the resulting space-charge electric field on the ... More

The Uniform Electron Gas at Warm Dense Matter ConditionsJan 17 2018We review the uniform electron gas (UEG) at finite temperature and over a broad density range relevant for warm dense matter (WDM) applications. We provide an overview of different simulation techniques, focusing on recent developments in the dielectric ... More

Laser wakefield acceleration with mid-IR laser pulsesJan 16 2018Jan 17 2018We report on the first results of laser plasma wakefield acceleration driven by ultrashort mid-infrared laser pulses (\lambda= 3.9 \mu m, 100 fs, 0.25 TW), which enable near- and above-critical density interactions with moderate-density gas jets. Relativistic ... More

Adaptive Kinetic-Fluid Models for Expanding PlasmasJan 15 2018We describe gas dynamic and plasma effects for transient plasma jets under different conditions. Our Unified Flow Solver (UFS) is evaluated for simulations of mixed continuum-rarefied flows, transient gas expansion dynamics and collisionless plasma expansion. ... More

Feedforward and feedback control of locked mode phase and rotation in DIII-D with application to modulated ECCD experimentsJan 15 2018The toroidal phase and rotation of otherwise locked magnetic islands of toroidal mode number n=1 are controlled in the DIII-D tokamak by means of applied magnetic perturbations of n=1. Pre-emptive perturbations were applied in feedforward to "catch" the ... More

Spatially inhomogeneous acceleration of electrons in solar flaresJan 15 2018The imaging spectroscopy capabilities of the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) enable the examination of the accelerated electron distribution throughout a solar flare region. In particular, it has been revealed that the energisation ... More

Intermittent fluctuations due to uncorrelated Lorentzian pulsesJan 15 2018Fluctuations due to a super-position of uncorrelated Lorentzian pulses with a random distribution of amplitudes and duration times are considered. These are demonstrated to be strongly intermittent in the limit of weak pulse overlap, resulting in large ... More

Gas cell density characterization for laser wakefield accelerationJan 12 2018In the design of laser plasma electron injectors for multi-stage laser driven wakefield accelerators, the control of plasma density is a key element to stabilize the acceleration process. A cell with variable parameters is used to confine the gas and ... More

Whispering gallery effect in relativistic opticsJan 12 2018A relativistic laser pulse, confined in a cylindrical target, performs multiple scattering along the target surface. The confinement property of the target results in a very effcient interaction. This proccess, which is just yet another example of the ... More

Turbulent heating in an inhomogeneous, magnetised plasma slabJan 12 2018Observational evidence in space and astrophysical plasmas with long collisional mean free path suggests that more massive charged particles may be preferentially heated. One possible mechanism for this is the turbulent cascade of energy from injection ... More

Scattering of radio frequency waves by cylindrical blobs in the plasma edge in tokamaksJan 05 2018Radio frequency waves are routinely used in tokamak fusion plasmas for plasma heating, current control, and as well as in diagnostics. These waves are excited by antenna structures placed near the tokamak's wall and they have to propagate through a turbulent ... More

Linear discriminant analysis based predator-prey analysis of hot electron effects on the X-pinch plasma produced K-shell Aluminum spectraJan 03 2018Linear Discriminant Analysis (LDA) is applied to investigate the electron beam effects on the X-pinch produced K-shell Aluminum synthetic spectra. The radiating plasma is produced by the explosion of two 25-{\mu}m Al wires on a compact L-C (40kV, 200kA ... More

The Physical Foundation of the Reconnection Electric FieldJan 03 2018Jan 05 2018We report on computer simulations and analytic theory to provide a self-consistent understanding of the role of the reconnection electric field, which extends substantially beyond the simple change of magnetic connections. Rather, we find that the reconnection ... More

Hydrodynamic, Optically-Field-Ionized (HOFI) Plasma ChannelsJan 02 2018Jan 04 2018We present experiments and numerical simulations which demonstrate that fully-ionized, low-density plasma channels can be formed by hydrodynamic expansion of plasma columns produced by optical field ionization (OFI). The laser energy required to generate ... More

Generation of large-scale vorticity in rotating stratified turbulence with inhomogeneous helicity: mean-field theoryJan 01 2018We discuss a mean-field theory of generation of large-scale vorticity in a rotating density stratified developed turbulence with inhomogeneous kinetic helicity. We show that the large-scale nonuniform flow is produced due to ether a combined action of ... More

Laser-induced plasma generation of terahertz radiation using three incommensurate wavelengthsDec 31 2017We present the generation of THz radiation by focusing ultrafast laser pulses with three incommensurate wavelengths to form a plasma. The three colors include 800 nm and the variable IR signal and idler outputs from an optical parametric amplifier. Stable ... More

Compressibility effects in turbulent MHD and passive scalar transport: mean-field theoryDec 30 2017We develop a mean-field theory of compressibility effects in turbulent magnetohydrodynamics and passive scalar transport using the quasi-linear approximation and the spectral $\tau$-approach. We find that compressibility decreases the $\alpha$ effect ... More

Propagation speed, linear stability, and ion acceleration in radially imploding Hall-driven electron-magnetohydrodynamic shocksDec 29 2017Plasma density gradients are known to drive magnetic shocks in electron-magnetohydrodynamics (EMHD). Previous slab modeling has been extended to cylindrical modeling of radially imploding shocks. The main new effect of the cylindrical geometry is found ... More

Potentials of EUV light source based on microwave discharge in expanding jet of dense xenon plasmaDec 28 2017Feb 08 2018We discuss a concept of a point-like source of the extreme ultraviolet (EUV) light based on a non-equilibrium microwave discharge in expanding jet of dense xenon plasma with multiply charged ions. A conversion efficiency of microwave radiation to EUV ... More

Coexistence of weak and strong wave turbulence in incompressible Hall magnetohydrodynamicsDec 28 2017We report a numerical investigation of three dimensional, incompressible, Hall magnetohydrodynamic turbulence with a relatively strong mean magnetic field. Using helicity decomposition and cross-bicoherence analysis, we observe that the resonant three--wave ... More

Emergence of Spatial Order in Highly Interacting Rydberg GasesDec 28 2017We describe the emergence of strong spatial correlations, akin to liquid-like behavior and crystallization effects, in low (one and two) dimensional gases of cold Rydberg atoms. The presence of an external electric field permanently polarizes the atoms, ... More

Collisionless Kinetic Theory of Oblique Tearing InstabilitiesDec 27 2017The linear dispersion relation for collisionless kinetic tearing instabilities is calculated for a Harris equilibrium. In contrast to the conventional 2D geometry, which considers only modes at the center of the current sheet, modes can span the current ... More

Dust-acoustic rogue waves in an opposite polarity dusty plasma featuring non-extensive statisticsDec 27 2017Modulational instability (MI) of dust acoustic waves (DAWs), which propagates in an opposite polarity dusty plasma system, containing inertial warm negatively and positively charged dust particles as well as non-extensive q-distributed elec- trons and ... More

Parametric Instability, Inverse Cascade, and the $1/f$ Range of Solar-Wind TurbulenceDec 26 2017In this paper, weak turbulence theory is used to investigate the nonlinear evolution of the parametric instability in 3D low-$\beta$ plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are ... More

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma ChannelDec 25 2017Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma ... More

Laser Driving Highly Collimated $γ$-ray Pulses for the Generation of $μ^-μ^+$ and $e^-e^+$ Pairs in $γ-γ$ ColliderDec 24 2017A scheme to generate highly collimated $\gamma$-ray pulse is proposed for the production of muon and electron pairs in $\gamma-\gamma$ collider. The $\gamma$-ray pulse, with high conversion efficiency, can be produced as the result of electron phase-locked ... More

Ion Species Stratification Within Strong Shocks in Two-Ion PlasmasDec 22 2017Strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan ${\it et \ al.}$, PRE ${\bf 96}$, 053203 (2017)] answered in detail a ... More

Wave kinetics of drift-wave turbulence and zonal flows beyond the ray approximationDec 22 2017Jan 30 2018Inhomogeneous drift-wave turbulence can be modeled as an effective plasma where drift waves act as quantumlike particles and the zonal-flow velocity serves as a collective field through which they interact. We report the first Wigner--Moyal simulations ... More

Multi-color, femtosecond $γ$-ray pulse trains driven by comb-like electron beamsDec 22 2017Photon engineering can be exploited to control the nonlinear evolution of the drive pulse in a laser-plasma accelerator (LPA), offering new avenues to tailor electron beam phase space on a femtosecond time scale. One promising option is to drive an LPA ... More

Stochastic effects on phase-space holes and clumps in kinetic systems near marginal stabilityDec 18 2017The creation and subsequent evolution of marginally-unstable modes have been observed in a wide range of fusion devices. This behaviour has been successfully explained, for a single frequency shifting mode, in terms of phase-space structures known as ... More

A Hybridizable Discontinuous Galerkin solver for the Grad-Shafranov equationDec 12 2017In axisymmetric fusion reactors, the equilibrium magnetic configuration can be expressed in terms of the solution to a semi-linear elliptic equation known as the Grad-Shafranov equation, the solution of which determines the poloidal component of the magnetic ... More

Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyondDec 11 2017Plasma turbulence, and edge density fluctuations in particular, can under certain conditions broaden the cross-section of injected microwave beams significantly. This can be a severe problem for applications relying on well-localized deposition of the ... More

Perpendicular relativistic shocks in magnetized pair plasmaDec 07 2017Perpendicular relativistic ($\gamma_0=10$) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the ... More

Magnetic reconnection in strongly magnetized regions of the low solar chromosphereDec 02 2017Dec 22 2017Magnetic reconnection in strongly magnetized regions around the temperature minimum region of the low solar atmosphere is studied by employing MHD-based simulations of a partially ionized plasma within a reactive 2.5D multi-fluid model. It is shown that ... More

The Mochi.LabJet experiment for measurements of canonical helicity injection in a laboratory astrophysical jetNov 20 2017The Mochi device is a new pulsed power plasma experiment designed to produce long, collimated, stable, magnetized plasma jets when set up in the LabJet configuration. The LabJet configuration aims to simulate an astrophysical jet in the laboratory by ... More

Calculations for the Practical Applications of Quadratic Helicity in MHDOct 24 2017For the quadratic helicity $\chi^{(2)}$ we present a generalization of the Arnol'd inequality which relates the magnetic energy to the quadratic helicity, which poses a lower bound. We then introduce the quadratic helicity density using the classical ... More

Resolving ECRH deposition broadening due to edge turbulence in DIII-D by heat deposition measurementOct 10 2017Interaction between microwave power, used for local heating and mode control, and density fluctuations can produce a broadening of the injected beam, as confirmed in experiment and simulation. Increased power deposition width could impact suppression ... More

Resolving ECRH deposition broadening due to edge turbulence in DIII-D by 3D full-wave simulationsOct 09 2017Edge plasma density fluctuations are shown to have a significant effect on the electron cyclotron resonance heating (ECRH) beam in the DIII-D tokamak. Experimental measurements of the ECRH deposition profile have been taken in three operating scenarios: ... More

Enhancing laser-driven proton acceleration by using micro-pillar arrays at high drive energySep 19 2017The interaction of micro- and nano-structured target surfaces with high-power laser pulses is being widely investigated for its unprecedented absorption efficiency. We have developed vertically aligned metallic micro-pillar arrays for laser-driven proton ... More

Carrier-envelope phase controlled isolated attosecond pulses in the nm wavelength range, based on superradiant nonlinear Thomson-backscatteringSep 07 2017Dec 18 2017A proposal for a novel source of isolated attosecond XUV -- soft X-ray pulses with a well controlled carrier-envelope phase difference (CEP) is presented in the framework of nonlinear Thomson-backscattering. Based on the analytic solution of the Newton-Lorentz ... More

\textit{Ab Initio} results for the Static Structure Factor of the Warm Dense Electron GasSep 07 2017The uniform electron gas at finite temperature is of high current interest for warm dense matter research. The complicated interplay of quantum degeneracy and Coulomb coupling effects is fully contained in the pair distribution function or, equivalently, ... More

Evidence of strong radiation reaction in the field of an ultra-intense laserSep 06 2017Jan 08 2018The motion of an electron in an external field of arbitrary intensity is one of the most fundamental outstanding problems in electrodynamics. Remarkably, there is no unanimously accepted theoretical solution for high intensities and little or no experimental ... More

Excitation and Control of Plasma Wakefields by Multiple Laser PulsesAug 14 2017We demonstrate experimentally the resonant excitation of plasma waves by trains of laser pulses. We also take an important first step to achieving an energy recovery plasma accelerator by showing that unused wakefield energy can be removed by an out-of-resonance ... More

Experimental evidence of radiation reaction in the collision of a high-intensity laser pulse with a laser-wakefield accelerated electron beamJul 21 2017Jan 04 2018The dynamics of energetic particles in strong electromagnetic fields can be heavily influenced by the energy loss arising from the emission of radiation during acceleration, known as radiation reaction. When interacting with a high-energy electron beam, ... More

Kinetic study of plasma current start-up under EBW power in tokamak plasmasMay 18 2017Tokamak plasma current start-up assisted by Electron Bernstein waves (EBW) has been demonstrated successfully in a number of experiments. The dynamic start-up phase involves a change in field topology, as the initially open magnetic field lines form closed ... More

Radiation Pressure Driven Ion Weibel Instability and Collisionless ShocksMay 15 2017Aug 11 2017The Weibel instability from counterstreaming plasma flows is a basic process highly relevant for collisionless shock formation in astrophysics. In this Letter we investigate, via two- and three- dimensional simulations, suitable configurations for laboratory ... More

High Flux Femtosecond X-ray Emission from the Electron-Hose Instability in Laser Wakefield AcceleratorsMay 02 2017Bright and ultrashort duration X-ray pulses can be produced by through betatron oscillations of electrons during Laser Wakefield Acceleration (LWFA). Our experimental measurements using the \textsc{Hercules} laser system demonstrate a dramatic increase ... More

In-situ analysis of optically thick nanoparticle cloudsMay 02 2017Nanoparticles grown in reactive plasmas and nanodusty plasmas gain high interest from basic science and technology. One of the great challenges of nanodusty plasmas is the in-situ diagnostic of the nanoparticle size and refractive index. The analysis ... More

Fast Magnetic Reconnection: "Ideal" Tearing and the Hall EffectApr 28 2017One of the main questions in magnetic reconnection is the origin of triggering behavior with on/off properties that accounts, once it is activated, for the fast magnetic energy conversion to kinetic and thermal energies at the heart of explosive events ... More

QDB: a new database of plasma chemistries and reactionsApr 13 2017One of the most challenging and recurring problems when modelling plasmas is the lack of data on key atomic and molecular reactions that drive plasma processes. Even when there are data for some reactions, complete and validated datasets of chemistries ... More

A kinetic study of microwave start-up of tokamak plasmasApr 03 2017A kinetic model for studying the time evolution of the distribution function for microwave start-up is presented. The model for the distribution function is two dimensional in momentum space, but, for simplicity and rapid calculations, has no spatial ... More

Ab initio Exchange-Correlation Free Energy of the Uniform Electron Gas at Warm Dense Matter ConditionsMar 23 2017In a recent Letter [T.~Dornheim \textit{et al.}, Phys. Rev. Lett. \textbf{117}, 156403 (2016)], we presented the first \textit{ab initio} quantum Monte-Carlo (QMC) results of the warm dense electron gas in the thermodynamic limit. However, a complete ... More

Perturbing microwave beams by plasma density fluctuationsMar 15 2017The propagation of microwaves across a turbulent plasma density layer is investigated with full-wave simulations. To properly represent a fusion edge-plasma, drift-wave turbulence is considered based on the Hasegawa-Wakatani model. Scattering and broadening ... More

Evolving waves and turbulence in the outer corona and inner heliosphere: the accelerating expanding boxFeb 09 2017May 08 2017Alfv\'enic fluctuations in the solar wind display many properties reflecting an ongoing nonlinear cascade, e.g. a well-defined spectrum in frequency, together with some characteristics more commonly associated with the linear propagation of waves from ... More

Quantifying the Tangling of Trajectories Using the Topological EntropyFeb 01 2017Oct 18 2017We present a simple method to efficiently compute a lower limit of the topological entropy and its spatial distribution for two-dimensional mappings. These mappings could represent either two-dimensional time-periodic fluid flows or three-dimensional ... More