Large-amplitude electric fields in the inner magnetosphere: Van Allen Probes observations of subauroral polarization streams

The subauroral polarization stream (SAPS) is an important magnetosphere-ionosphere (MI) coupling phenomenon that impacts a range of particle populations in the inner magnetosphere. SAPS studies often emphasize ionospheric signatures of fast westward flows, but the equatorial magnetosphere is also affected through strong radial electric fields in the dusk sector. This study focuses on a period of steady southward interplanetary magnetic field (IMF) during the 29 June 2013 geomagnetic storm where the Van Allen Probes observe a region of intense electric fields near the plasmapause over multiple consecutive outbound duskside passes. We show that the large-amplitude electric fields near the equatorial plane are consistent with SAPS by investigating the relationship between plasma sheet ion and electron boundaries, associated field-aligned currents, and the spatial location of the electric fields. By incorporating high-inclination DMSP data we demonstrate the spatial and temporal variability of the SAPS region, and we suggest that discrete, earthward propagating injections are driving the observed strong electric fields at low L shells in the equatorial magnetosphere. We also show the relationship between SAPS and plasmasphere erosion, as well as a possible correlation with flux enhancements for 100s keV electrons

Breakdown of the Landauer bound for information erasure in the quantum regime

A known aspect of the Clausius inequality is that an equilibrium system subjected to a squeezing \d S of its entropy must release at least an amount |\dbarrm Q|=T|\d S| of heat. This serves as a basis for the Landauer principle, which puts a lower bound $T\ln 2$ for the heat generated by erasure of one bit of information. Here we show that in the world of quantum entanglement this law is broken. A quantum Brownian particle interacting with its thermal bath can either generate less heat or even {\it adsorb} heat during an analogous squeezing process, due to entanglement with the bath. The effect exists even for weak but fixed coupling with the bath, provided that temperature is low enough. This invalidates the Landauer bound in the quantum regime, and suggests that quantum carriers of information can be much more efficient than assumed so far.Comment: 13 pages, revtex, 2 eps figure

Population control of 2s-2p transitions in hydrogen

We consider the time evolution of the occupation probabilities for the 2s-2p transition in a hydrogen atom interacting with an external field, V(t). A two-state model and a dipole approximation are used. In the case of degenerate energy levels an analytical solution of the time-dependent Shroedinger equation for the probability amplitudes exists. The form of the solution allows one to choose the ratio of the field amplitude to its frequency that leads to temporal trapping of electrons in specific states. The analytic solution is valid when the separation of the energy levels is small compared to the energy of the interacting radiation.Comment: 6 pages, 3 figure

On the validity of entropy production principles for linear electrical circuits

We discuss the validity of close-to-equilibrium entropy production principles in the context of linear electrical circuits. Both the minimum and the maximum entropy production principle are understood within dynamical fluctuation theory. The starting point are Langevin equations obtained by combining Kirchoff's laws with a Johnson-Nyquist noise at each dissipative element in the circuit. The main observation is that the fluctuation functional for time averages, that can be read off from the path-space action, is in first order around equilibrium given by an entropy production rate. That allows to understand beyond the schemes of irreversible thermodynamics (1) the validity of the least dissipation, the minimum entropy production, and the maximum entropy production principles close to equilibrium; (2) the role of the observables' parity under time-reversal and, in particular, the origin of Landauer's counterexample (1975) from the fact that the fluctuating observable there is odd under time-reversal; (3) the critical remark of Jaynes (1980) concerning the apparent inappropriateness of entropy production principles in temperature-inhomogeneous circuits.Comment: 19 pages, 1 fi

An optimization principle for deriving nonequilibrium statistical models of Hamiltonian dynamics

A general method for deriving closed reduced models of Hamiltonian dynamical systems is developed using techniques from optimization and statistical estimation. As in standard projection operator methods, a set of resolved variables is selected to capture the slow, macroscopic behavior of the system, and the family of quasi-equilibrium probability densities on phase space corresponding to these resolved variables is employed as a statistical model. The macroscopic dynamics of the mean resolved variables is determined by optimizing over paths of these probability densities. Specifically, a cost function is introduced that quantifies the lack-of-fit of such paths to the underlying microscopic dynamics; it is an ensemble-averaged, squared-norm of the residual that results from submitting a path of trial densities to the Liouville equation. The evolution of the macrostate is estimated by minimizing the time integral of the cost function. The value function for this optimization satisfies the associated Hamilton-Jacobi equation, and it determines the optimal relation between the statistical parameters and the irreversible fluxes of the resolved variables, thereby closing the reduced dynamics. The resulting equations for the macroscopic variables have the generic form of governing equations for nonequilibrium thermodynamics, and they furnish a rational extension of the classical equations of linear irreversible thermodynamics beyond the near-equilibrium regime. In particular, the value function is a thermodynamic potential that extends the classical dissipation function and supplies the nonlinear relation between thermodynamics forces and fluxes

Asymptotology of Chemical Reaction Networks

The concept of the limiting step is extended to the asymptotology of multiscale reaction networks. Complete theory for linear networks with well separated reaction rate constants is developed. We present algorithms for explicit approximations of eigenvalues and eigenvectors of kinetic matrix. Accuracy of estimates is proven. Performance of the algorithms is demonstrated on simple examples. Application of algorithms to nonlinear systems is discussed.Comment: 23 pages, 8 figures, 84 refs, Corrected Journal Versio

Anthropogenic Space Weather

Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

Relation between magnetosonic waves and pitch angle anisotropy of warm protons

In the past decade, many observations of transversely heated low energy protons were reported in the inner magnetosphere. Interestingly, most of the time heated protons were observed along with magnetosonic waves. Due to the strong correlation, it was often assumed that magnetosonic waves were responsible for the heating of low energy protons. By performing a case study under unusually disturbed geomagnetic conditions, this paper unravels the controversial relationship between the observed pitch angle anisotropy of warm protons and the accompanying magnetosonic waves in the inner magnetosphere. We perform a comparative analysis involving two nearly identical cases of pitch angle anisotropy of warm protons in low L-shell region–one with magnetosonic waves and one without them. It is found that magnetosonic waves are not responsible for primary heating of low-energy protons and may just marginally alter the shape of the distribution of heated protons in the events analyzed. Based on the recent Cluster and POLAR observations, we also show how the recirculated polar wind plasma in the Earth’s magnetosphere can cause the concurrent appearance of heated protons and magnetosonic waves.FG-2018-10936 - Alfred P. Sloan FoundationPublished versio

Substorm driven chorus waves: Decay timescales and implications for pulsating aurora

Energetic electron precipitation (EEP) associated with pulsating aurora can transfer greater than 30 keV electrons from the outer radiation belt region into the upper atmosphere and can deplete atmospheric ozone via collisions that produce NOx and HOx molecules. Our knowledge of exactly how EEP occurs is incomplete. Previous studies have shown that pitch angle scattering between electrons and lower-band chorus waves can cause pulsating aurora associated with EEP and that substorms play an important role. In this work, we quantify the timescale of chorus wave decay following substorms and compare that to previously determined timescales. We find that the chorus decay e-folding time varies based on magnetic local time (MLT), magnetic latitude, and wave frequency. The shortest timescales occur for lower-band chorus in the 21 to 9 MLT region and compares, within uncertainty, to the energetic pulsating aurora timescale of Troyer et al. (2022, https://doi.org/10.3389/fspas.2022.1032552) for energetic pulsating aurora. We are able to further support this connection by modeling our findings in a quasi-linear diffusion simulation. These results provide observations of how chorus waves behave after substorms and add additional statistical evidence linking energetic pulsating aurora to substorm driven lower-band chorus waves

Origins of the Ambient Solar Wind: Implications for Space Weather

The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure