Magnetic Field Reconstruction for a Realistic Multi-Point, Multi-Scale Spacecraft Observatory

Future in situ space plasma investigations will likely involve spatially distributed observatories comprised of multiple spacecraft, beyond the four and five spacecraft configurations currently in operation. Inferring the magnetic field structure across the observatory, and not simply at the observation points, is a necessary step towards characterizing fundamental plasma processes using these unique multi-point, multi-scale data sets. We propose improvements upon the classic first-order reconstruction method, as well as a second-order method, utilizing magnetometer measurements from a realistic nine-spacecraft observatory. The improved first-order method, which averages over select ensembles of four spacecraft, reconstructs the magnetic field associated with simple current sheets and numerical simulations of turbulence accurately over larger volumes compared to second-order methods or first-order methods using a single regular tetrahedron. Using this averaging method on data sets with fewer than nine measurement points, the volume of accurate reconstruction compared to a known magnetic vector field improves approximately linearly with the number of measurement points.Comment: 18 pages, 12 figures, 3 table

HelioSwarm: A Multipoint, Multiscale Mission to Characterize Turbulence

HelioSwarm (HS) is a NASA Medium-Class Explorer mission of the Heliophysics Division designed to explore the dynamic three-dimensional mechanisms controlling the physics of plasma turbulence, a ubiquitous process occurring in the heliosphere and in plasmas throughout the universe. This will be accomplished by making simultaneous measurements at nine spacecraft with separations spanning magnetohydrodynamic and sub-ion spatial scales in a variety of near-Earth plasmas. In this paper, we describe the scientific background for the HS investigation, the mission goals and objectives, the observatory reference trajectory and instrumentation implementation before the start of Phase B. Through multipoint, multiscale measurements, HS promises to reveal how energy is transferred across scales and boundaries in plasmas throughout the universe

Laser Spark Ignition Modeling

Laser spark phenomena are studied in air and ammonia-oxygen mixtures by the use of a two-dimensional, axially-symmetric, time-accurate computational fluid dynamic model. The initial laser spark temperature distribution is generated to simulate a post-breakdown profile that is consistent with theoretical, experimental, and computational investigations for a nominal 10-ns optical breakdown laser pulse. Thermodynamic properties of various species are extended to 35,000 K to cover the range of the initial temperature distribution. The developed computational model includes a kinetics mechanism that implements plasma equilibrium kinetics in ionized regions. The computational model time-accurately predicts species concentrations, free electron number density decay, blast wave formation and propagation, vortex formations, temperature profiles, ignition kernel dynamics, flame front formation and propagation, and flow field interactions of laser spark decay in various non-combustible and combustible gaseous mixtures. The computationally predicted fluid phenomena are shown to agree with various flow patterns characteristic of laser spark decay by direct comparison with experimental records

A New Method of 3-D Magnetic Field Reconstruction

A method is described to model the magnetic field in the vicinity of three-dimensional constellations of satellites (at least four) using field and plasma current measurements. This quadratic model matches the measured values of the magnetic field and its curl (current) at each spacecraft, with ∇ • B zero everywhere, and thus extends the linear curlometer method to second order. Near the spacecraft, it predicts the topology of magnetic structures, such as reconnecting regions or flux ropes, and allows a tracking of the motion of these structures relative to the spacecraft constellation. Comparisons to particle-in-cell simulations estimate the model accuracy. Reconstruction of two electron diffusion regions definitively confirms the expected field line structure. The model can be applied to other small-scale phenomena (e.g., bow shocks) and can also be modified to reconstruct the electric field, allowing tracing of particle trajectories

Two‐dimensional velocity of the magnetic structure observed on 11 July 2017 by the Magnetospheric Multiscale spacecraft

International audienceIn order to determine particle velocities and electric field in the frame of the magnetic structure, one first needs to determine the velocity of the magnetic structure in the frame of the spacecraft observations. Here, we demonstrate two methods to determine a two-dimensional magnetic structure velocity for the magnetic reconnection event observed in the magnetotail by the Magnetospheric Multiscale (MMS) spacecraft on July 11, 2017, Spatio-Temporal Difference (STD) and the recently developed polynomial reconstruction method. Both of these methods use the magnetic field measurements; the reconstruction technique also uses the current density measured by the particle instrument. We find rough agreement between the results of our methods and with other velocity determinations previously published. We also explain a number of features of STD and show that the polynomial reconstruction technique is most likely to be valid within a distance of 2 spacecraft spacings from the centroid of the MMS spacecraft. Both of these methods are susceptible to contamination by magnetometer calibration errors

Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 White Paper Plasma turbulence: Challenges and next transformative steps from the perspective of multi-spacecraft measurements

Synopsis We recommend to bring into reality the following within the next decade: 1. Measurements from multiple spacecraft covering a 3D volume and simultaneously spanning the MHD to kinetic scales (such as HelioSwarm). 2. Coordination of the new multi-scale mission(s) with existing multi-spacecraft missions such as MMS to maximize the power of cross-scale ion and electron measurements

Disentangling the Spatiotemporal Structure of Turbulence Using Multi-Spacecraft Data

This white paper prepared for the 2024 Decadal Survey for Solar and Space Physics concerns the importance of research related to multi-spacecraft missions to address fundamental questions concerning plasma turbulence. In this white paper, some of the important questions facing the turbulence community that can only be addressed by funding research related to multipoint measurements are presented