Paper: Issan O, Koshkarov O, Halpern F, Kramer B, Delzanno GL (2024). Anti-symmetric and Positivity Preserving Formulation of a Spectral Method for Vlasov-Poisson Equations. Journal of Computational Physics (in press). doi: 10.1016/j.jcp.2024.113263
Plasma wave theory involves understanding how the perturbation of particle orbits by mean-field waves produces charge densities and currents that self-consistently create the mean-fields. Exact solutions are known in only a few special cases. However, given this self-consistent relationship, it is natural to ask – how much about the wave fields in a given region of space can be known by...
Magnetic reconnection is an ubiquitous phenomenon observed in laboratory, fusion and space plasmas. It is usually accompanied by the energy conversion between electromagnetic fields and plasmas [1]. Recently, a new regime called “electron-only magnetic reconnection” (e-rec hereafter) was observed and studied in the Earth’s magnetosheath [2] and in laboratory plasmas [3]. The novelty of e-rec...
We present the formation of positronium (Ps) through charge-exchange of magnetically confined positrons and background gas in the laboratory. A bunch of 10⁵ positrons is extracted from a buffer-gas trap and injected into the dipole field of a permanent magnet trap with E×B drifts [1]. Once injected, the positrons are confined through a combination of magnetic mirroring and electrostatic...
Alfvénic fluctuations - fluctuations with magnetic-field and velocity fluctuations perpendicular to the background magnetic field which are proportional to each other - are thought to be ubiquitous in magnetized astrophysical plasma environments and are observed across scales in our own solar wind. Recent theoretical work by Mallet et al [1] proposes a mechanism by which small-scale, oblique...
We investigate tearing modes driven by current density gradient in collisionless tokamak plasmas by using the electromagnetic gyrokinetic simulation code ORB5. Two aspects of the dynamics of magnetic island due to the tearing mode, its width and rotation, are studied by simulations for flat and finite-gradient profiles of density and temperature. The evolution of the width (rotation) is...
In controlled laboratory setups, when lasers interact with solid or gaseous targets, various phenomena such as shock formation, plasma instability, and magnetic reconnection can be observed. Understanding the behavior of electromagnetic fields in plasmas is crucial in these experiments. To measure these fields, scientists utilize a method called ion radiography, also known as proton imaging....
Magnetic reconnection has been established as a fast and efficient particle accelerator in dramatic astrophysical flares. However, the significance of nonideal fields in the early states ("injection") of acceleration has been debated. Using particle-in-cell simulations, we demonstrate the importance of nonideal fields in accelerating the particles to high energies. We define nonideal fields as...
The Magnetized Plasma Research Laboratory (MPRL) at Auburn University explores fundamental plasma and complex/dusty plasma phenomena covering a large parameter regime from unmagnetized plasmas to strongly magnetized plasmas with a mission to serve as an open access, multi-user collaborative research facility. The centerpiece of the laboratory is the Magnetized Dusty Plasma Experiment (MDPX), a...
Advanced thrusters are needed for deep space missions to Mars and beyond. For such thrusters, it is critical to determine how to generate large thrust-to-power at sufficiently high specific impulse with long lifetime and flexibility in propellant. To address these challenges, we are exploring a new electrodeless Magnetic Reconnection Thruster (e-MRT), which will use asymmetric,...
Nonthermal particle acceleration is believed to account for a large portion of the energy dissipated during magnetic reconnection. However, this process remains poorly understood, and laboratory observation of non-thermal acceleration remains limited. Here, we present a novel design for a multi-channel electron energy analyzer for studies of electron acceleration in magnetic reconnection. This...
Local precipitation loss due to pitch angle scattering by magnetospheric waves is the focus of our analysis. Plasma waves can alter the course of a charged particle and influence a previously trapped electron from the magnetosphere to penetrate the Earth’s upper atmosphere. Once in the upper atmosphere, a charge particle can ionize air molecules leading to the destruction of ozone and...
Coulomb collisions effectively relax plasma velocity distribution function to a near-Maxwellian form and often hamper the relevance of laboratory experiments to tenuous and near-collisionless space plasma. To overcome this challenge, the Terrestrial Reconnection Experiment (TREX)[1] at the Wisconsin Plasma Physics Laboratory (WiPPL)[2] is specially designed to be relevant to reconnection in...
Turbulence and magnetic reconnection are intrinsic to space and astrophysical plasmas. Recent observations revealed a novel type of reconnection occurring in the turbulent Earth’s magnetosheath, dubbed “electron-only reconnection” [Phan 2018]. This distinctive form of reconnection occurs in the absence of ion outflows, signifying a reconnection event without an Ion Diffusion Region (IDR). 2D...
Weakly magnetized plasmas are found in natural plasmas such as the solar wind, but also in laboratory applications, e.g. in the edge of fusion plasmas. Ordering assumptions made in gyrokinetic theory—like low frequency or moderate gradients—may be challenged, particularly for the heavier ions. To overcome these limitations, the group derived equations for a hybrid model that includes fully...
Coronal Mass Ejections (CMEs) are major drivers of Space Weather (SWx) effects on Earth, and predicting their arrival is a major aspect of SWx forecast. Several CME propagation models have been developed for this purpose, but the overall arrival time error still exceeds 12 hours. In this study, we aim to improve these predictions by employing machine learning (ML) techniques that utilize the...
Turbulence is ubiquitous throughout different space plasma environments, facilitating the cascade of energy down to smaller and smaller length scales. That said, the different parameter regimes at which these plasmas exist have a significant effect on the way the cascade develops- turbulence at the MHD limit will not have the same attributes as turbulence at the kinetic limit. For instance,...
Terrella (“little Earth” [1]) is a metalized spherical magnet with a dipolar magnetic field that can serve as a laboratory model of compact space objects with large magnetic fields (neutron stars, white dwarfs, etc.). In our case, Terrella is a spherical neodymium magnet with a diameter of $19~\mathrm{mm}$ supplied by high voltage (up to $400\,\mathrm{V}$) at a pressure between...
Collisionless shocks are ubiquitous objects in the universe. Many of these shocks are magnetized due to preexisting magnetic fields in the upstream, which is the case for the Earth’s bowshock in heliophysics and supernova remnants. Despite decades of observations and numerical simulations, there remains no clear understanding on how energy is partitioned between electrons and ions across a...
Our multi-view soft X-ray measurement system detected for the first time high-energy electrons localized at the X-point of two merging tokamak plasmas. We found their energies increase with the guide toroidal field. These electrons are considered to be accelerated by the reconnection electric field along the guide magnetic field.
Under a high guide field, the reconnection electric field is...
Neutron stars are rotating objects with a strong magnetic field. The consequent induced field in the rotating reference frame is expected to support the creation of pair plasma in the vicinity of the neutron star. Presumably, electrons and positrons reside in separated domains above the poles and around the equator. This model is supported by several fully kinetic particle-in-cell (PIC)...
Magnetic reconnection is a ubiquitous plasma phenomenon that plays an important role in particle heating and energization. During reconnection, the topology of magnetic field rearranges, depositing energy into the surrounding plasma through bulk flow, thermal heating, or non-thermal particle acceleration. The pathways of this transformation from magnetic energy into kinetic have been studied...
Using tracer particles propagating in an environment that simulates the accretion disk surrounding a black hole, this work aims to provide insight into the confinement of high energy particles in the galaxy NGC 1068 ( J. Bland-Hawthorn et al., 1997, Astrophysics and Space Science; K. Murase, 2022, The Astrophysical Journal Letters ), which is believed to be the source of the neutrino...
The study of bound states in dense plasma has always been of great scientific interest. It is known that the plasma environment leads to screening of the charge’s field not only in free states but also in the bound states. In particular, this leads to broadening and shift of the spectral lines [1-2]. Also, due to the screening effect, as well as the energy level broadening in the external...
Collisions between charged and neutral particles in plasma can lead to energy and momentum transfer, which can affect plasma temperature and density profiles. Understanding and controlling these transport properties is necessary to achieve and maintain the conditions required for nuclear fusion reactions to occur in a tokamak.
In this study, we investigate collision frequency and energy...
The interaction region between the solar wind and planetary atmospheres is a critical window for investigating planetary evolution. Mars, with its complex magnetic environment, offers an ideal setting for studying this interaction region. Within this region, particles of varying energies interact in a complex plasma environment, facilitating diverse material and energy transfer processes. This...
