Electron Heating Rate Research Articles

Cascade-Dissipation Balance in Astrophysical Plasmas: Insights from the Terrestrial Magnetosheath.

The differential heating of electrons and ions by turbulence in weakly collisional magnetized plasmas and the scales at which such energy dissipation is most effective are still debated. Using a large data sample measured in Earth's magnetosheath by the magnetospheric multiscale mission and the coarse-grained energy equations derived from the Vlasov-Maxwell system, we find evidence of a balance over two decades in scales between the energy cascade and dissipation rates. The decline of the cascade rate at kinetic scales (in contrast with a constant one in the inertial range), is balanced by an increasing ion and electron heating rates, estimated via the pressure strain. Ion scales are found to contribute most effectively to ion heating, while electron heating originates from both ion and electron scales. These results can potentially impact the current understanding of particle heating in turbulent magnetized plasmas as well as their theoretical and numerical modeling.

Turbulence, and Proton and Electron Heating Rates in the Solar Corona: Analytical Approach

Analytical solutions for 2D and slab turbulence energies in the solar corona are presented, including a derivation of the corresponding correlation lengths, with implications for the proton and electron temperatures in the solar corona. These solutions are derived by solving the transport equations for 2D and slab turbulence energies and their correlation lengths, as well as proton and electron pressures. The solutions assume background profiles for the solar wind speed, solar wind mass density, and Alfvén velocity. Our analytical solutions can be related to those obtained from joint Parker Solar Probe and Solar Orbiter Metis coronagraph observations, as reported in Telloni et al. We find that the solution for 2D turbulence energy in the absence of nonlinear dissipation decreases more slowly compared to the dissipative solution. The solution for slab turbulence energy with no dissipation exhibits a more rapid increase compared to the dissipative solution. The proton heating rate is found to be about 82% of the total plasma heating rate at 6.3 R ⊙, which gradually decreases with increasing distance, eventually becoming ∼80% of the total plasma heating rate at ∼13 R ⊙, consistent with that found by Bandyopadhyay et al. (2023). These analytical solutions provide valuable insight for our understanding of turbulence, and its effect on proton and electron heating rates, in the solar corona. We compare the numerically solved turbulent transport equations for the 2D and slab turbulence energies, correlation lengths, and proton and electron pressures with the analytical solutions, finding good agreement between them.

The dynamical behavior of the capacitively coupled argon plasma driven by very high frequency

The dynamical behavior of the capacitively coupled Ar plasma driven by four frequencies (54, 80, 94 and 100[Formula: see text]MHz) at fixed pressure are simulated by the particle-in-cell/Monte-Carlo collisions (PIC/MCC) model based on the electromagnetic field. The magnetic field is generated by plasma current itself. The results show that the electron density, charge density, and electron temperature increase with the frequency increase when radio frequency (RF) power is 40[Formula: see text]W. The electron heating rate and argon ion heating rate near the sheath increase with the frequency increase. The high-energy electron density ([Formula: see text] [Formula: see text]eV) varies nonlinearly with the frequency increase. The high-energy electron density is highest at 80[Formula: see text]MHz among the four frequencies. The electron density, charge density, and high-energy electron density increase with RF power (30, 45, 60, and 75[Formula: see text]W) increase at 80[Formula: see text]MHz. The electron temperature decreases with RF power increase at 80[Formula: see text]MHz. The electron heating rate and argon ion heating rate near the sheath have no change with RF power increase at 80[Formula: see text]MHz. The electron energy probability distributions (EEPF) show that the number of high-energy electrons ([Formula: see text] [Formula: see text]eV) is highest at 80[Formula: see text]MHz. The reason may be the electron resonant heating that occurs in the plasma when the electron cyclotron frequency equals source frequency at 80[Formula: see text]MHz. The electron dynamics of capacitively coupled plasma is important for microelectronics etching and membrane deposition.

Investigation of core transport changes in DIII-D discharges with off-axis T e profile peaks

DIII-D discharges that transition to H-mode solely with off-axis electron cyclotron heating (ECH) often exhibit strong off-axis peaking of electron temperature profiles at the heating location. Electron heat transport properties near these off-axis temperature peaks have been studied using modulated ECH. The Fourier analyzed electron temperature data have been used to infer electron thermal diffusivity. Comparisons with numerical solutions of the time-dependent electron thermal equation find that the data are consistent with a narrow region with electron diffusivity χ e an order of magnitude lower than the average value across the plasma, suggesting an electron internal transport barrier (ITB) near the ECH heating location. Detailed profile analysis and equilibrium reconstructions suggest that the formation of these ITBs are correlated with off-axis values of the safety factor q being near 1. Furthermore, the ECH driven H-mode discharges demonstrate more rapid electron heating rate near the ECH deposition location than L-mode discharges with higher auxiliary ECH heating power. Additional modeling attributes this difference to the modification of electron heat transport in the core at the L-H transition, which also sustains the off-axis electron temperature peaks.

Calibrated heating rate measurements using electric-field-induced electron extraction in ultracold neutral plasmas

The heating rate of plasma electrons induced by external fields or other processes can be used as an experimental tool to measure fundamental plasma properties such as electrical conductivity or electron–ion collision rates. We have developed a technique that can measure electron heating rates in ultracold neutral plasmas (UNPs) with $\sim 10\,\%$ precision while simultaneously referencing the measurement to a calibrated amount of heating. This technique uses a sequence of applied electric fields in four sections: to control the ratio of electrons to ions in the UNP; to provide a time for the application of fields that cause electron heating and subsequent thermalization of the electrons after the application of those fields; to extract electrons from the UNP using a method sensitive to electron temperature that allows the measurement of electron heating; and to extract the remaining electrons to measure the total electron (and therefore ion) number. The primary signal used to measure the heating rate is the measurement of the number of electrons that escape in the third section of the experiment as a larger number of escaping electrons indicates a larger amount of heating. We illustrate the use of this technique by measuring electron heating caused by high-frequency radiofrequency (RF) fields. In addition to the main technique, several subtechniques to calibrate the electron temperature, electron density, amount of heating and applied RF field amplitude were developed as well.

Estimates of Proton and Electron Heating Rates Extended to the Near-Sun Environment

A central problem of space plasma physics is how protons and electrons are heated in a turbulent, magnetized plasma. The differential heating of charged species due to dissipation of turbulent fluctuations plays a key role in solar wind evolution. Measurements from previous heliophysics missions have provided estimates of proton and electron heating rates beyond 0.27 au. Using Parker Solar Probe (PSP) data accumulated during the first 10 encounters, we extend the evaluation of the individual rates of heat deposition for protons and electrons to a distance of 0.063 au (13.5 R ⊙) in the newly formed solar wind. The PSP data in the near-Sun environment show different behavior of the electron heat conduction flux from what was predicted from previous fits to Helios and Ulysses data. Consequently, the empirically derived proton and electron heating rates exhibit significantly different behavior than previous reports, with the proton heating becoming increasingly dominant over electron heating at decreasing heliocentric distances. We find that the protons receive about 80% of the total plasma heating at ≈13 R ⊙, slightly higher than the near-Earth values. This empirically derived heating partition between protons and electrons will help to constrain theoretical models of solar wind heating.

Heating rate of thermal electrons by the fast part of EDF in the ionosphere

An alternative conclusion to the work of W. R. Hoegy [“Thermal electron heating rate: A derivation,” J. Geophys. Res. 89(A2), 977–985 (1984)] is presented, and rigorous analytical expressions for heating thermal Maxwellian electrons by the fast part of the energy distribution function (EDF) with an arbitrary dependence on energy are obtained. This makes the calculation of thermal electron heating under specific conditions possible, as well as scaling the obtained results. For the most convenient bi-Maxwell approximation of the EDF, comparatively simple analytical expressions for heating, convenient for practical calculations, are obtained. It has been shown that these expressions are in good agreement with the results of the fundamental Hoegy's work. Analytical expressions for heating thermal electrons by fast electrons, with a power-law distribution dependence on energy, are also presented.

Energy dissipation in turbulent reconnection

We study the nature of pressure-strain interaction at reconnection sites detected by NASA's Magnetospheric Multiscale Mission. We employ data from a series of previously published case studies, including a large-scale reconnection event at the magnetopause, three small-scale reconnection events at the magnetosheath current sheets, and one example of the recently discovered electron-only reconnection. In all instances, we find that the pressure-strain shows a signature of conversion into (or from) internal energy at the reconnection site. The electron heating rate is larger than the ion heating rate and the compressive heating is dominant over the incompressive heating rate in all cases considered. The magnitude of thermal energy conversion rate is close to the electromagnetic energy conversion rate in the reconnection region. Although in most cases the pressure-strain interaction indicates that the particle internal energy is increasing, in one case, the internal energy is decreasing. These observations indicate that the pressure-strain interaction can be used as an independent measure of energy conversion and dynamics in reconnection regions, in particular, independent of measures based on the electromagnetic work. Finally, we explore a selected reconnection site in a turbulent Particle-in-Cell simulation which further supports the observational results.

In Situ Heating of the Nightside Martian Upper Atmosphere and Ionosphere: The Role of Solar Wind Electron Precipitation

Abstract In the absence of solar radiation, precipitating electrons from the solar wind (SW) are generally thought to be the dominant source of energy deposition in the nightside Martian upper atmosphere, creating a patchy ionosphere and possibly also affecting the nightside thermal budget of various neutral and ionized species. Previous model calculations have not taken into account in situ heating via SW electron impact. In the present study, we utilize extensive measurements made by several instruments on board the Mars Atmosphere and Volatile Evolution spacecraft, in order to perform data-driven computations of the nightside neutral, ion, and electron heating rates. Considering the large range of energetic electron intensity observed on the nightside of Mars, we divide the entire data set into two subsamples, either with or without energetic electron depletion, a notable feature of the nightside Martian ionosphere. Our calculations indicate that in situ nightside neutral heating is dominated by exothermic chemistry and Maxwell interaction with thermal ions for regions with depletion, and by direct SW impact for regions without. Collisional quenching of excited state species produced from a variety of channels, such as electron impact excitation, dissociation, and ionization, as well as dissociative recombination, makes a substantial contribution to neutral heating, except during depletion. For comparison, nightside ion heating is mainly driven by energetic ion production under all circumstances, which occurs mainly via ion-neutral reaction O+ + CO2 and CO2 + predissociation.

Electron Bernstein wave excitation and heating by nonlinear interactions of Laguerre and Hermite Gaussian laser beams in a magnetized plasma

In this paper, we have studied the nonlinear interaction of Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) laser beams in magnetized plasma, and electron Bernstein wave (EBW) excitation and heating of electron is evaluated. The beat wave with frequency ω=(ω1-ω2) and wave vector k→=k→1+k→2, exert a pondermotive force on electrons. This force has potential to drive electron Bernstein wave in both homogeneous and inhomogeneous plasma. The convective loss of waves in inhomogeneous plasma is discussed. An analytical theory is also developed for the anomalous heating of electrons. The variation of normalized potential and power distribution with normalized frequency and beam direction is demonstrated to excite EBWs under resonance conditions. The laser parameters such as beam width, modes index, and frequency affect the EBWs excitation and rate of electron heating. In addition, the spatial tuned shape of beams and the optimum laser beams parameter is proposed for much more exaction and heating.

Observations of Particle Acceleration in Magnetic Reconnection–driven Turbulence

Abstract The Magnetospheric Multiscale Mission observes, in detail, charged particle heating and substantial nonthermal acceleration in a region of strong turbulence ( , where is the magnetic field) that surrounds a magnetic reconnection X-line. Magnetic reconnection enables magnetic field annihilation in a volume that far exceeds that of the diffusion region. The formidable magnetic field annihilation breaks into strong, intermittent turbulence with magnetic field energy as the driver. The strong, intermittent turbulence appears to generate the necessary conditions for nonthermal acceleration. It creates intense, localized currents ( ) and unusually large-amplitude electric fields ( ). The combination of turbulence-generated and results in a significant net positive mean of , which signifies particle energization. Ion and electron heating rates are such that they experience a fourfold increase from their initial temperature. Importantly, the strong turbulence also generates magnetic holes or depletions in that can trap particles. Trapping considerably increases the dwell time of a subset of particles in the turbulent region, which results in significant nonthermal particle acceleration. The direct observation of strong turbulence that is enabled by magnetic reconnection with nonthermal particle acceleration has far-reaching implications, since turbulence in plasmas is pervasive and may occupy significant volumes of the interstellar medium and intergalactic space. For example, strong turbulence from magnetic field annihilation in the supernova nebulae may dominate large volumes. As such, this observed energization process could plausibly contribute to the supply and development of the cosmic-ray spectrum.

Electron heating by HF pumping of high-latitude ionospheric F-region plasma near magnetic zenith

Abstract. High-frequency electromagnetic pumping of ionospheric F-region plasma at high and mid latitudes gives the strongest plasma response in magnetic zenith, antiparallel to the geomagnetic field in the Northern Hemisphere. This has been observed in optical emissions from the pumped plasma turbulence, electron temperature enhancements, filamentary magnetic field-aligned plasma density irregularities, and in self-focusing of the pump beam in magnetic zenith. We present results of EISCAT (European Incoherent SCATter association) Heating-induced magnetic-zenith effects observed with the EISCAT UHF incoherent scatter radar. With heating transmitting a left-handed circularly polarized pump beam towards magnetic zenith, the UHF radar was scanned in elevation in steps of 1.0 and 1.5∘ around magnetic zenith. The electron energy equation was integrated to model the electron temperature and associated electron heating rate and optimized to fit the plasma parameter values measured with the radar. The experimental and modelling results are consistent with pump wave propagation in the L mode in magnetic zenith, rather than in the O mode.

Subsolar Electron Temperatures in the Lower Martian Ionosphere

AbstractMartian subsolar electron temperatures obtained below 250 km are examined using data obtained by instruments on the Mars Atmosphere Evolution Mission (MAVEN) during the three subsolar deep dip campaigns and a one‐dimensional fluid model. This analysis was done because of the uncertainty in MAVEN low electron temperature observations at low altitudes and the fact that the Level 2 temperatures reported from the MAVEN Langmuir Probe and Waves instrument are more than 400 K above the neutral temperatures at the lowest altitudes sampled (~120 km). These electron temperatures are well above those expected before MAVEN was launched. We find that an empirical normalization parameter, neutral pressure divided by local electron heating rate, organized the electron temperature data and identified a similar altitude (~160 km) and time scale (~2,000 s) for all three deep dips. We show that MAVEN data are not consistent with a plasma characterized by electrons in thermal equilibrium with the neutral population above 100 km. Because of the lack data below 120 km and the uncertainties of the data and the cross sections used in the one‐dimensional fluid model above 120 km, we cannot use MAVEN observations to prove that the electron temperature converges to the neutral temperature below 100 km. However, the uncertainty of the electron temperature altitude profile below 120 km does not impact our understanding of the role of electron temperature in determining ion escape rates because ion escape is determined by electron temperatures above 180 km.

Transplanet: A web service dedicated to modeling of planetary ionospheres

We present a new web service (http://transplanet.irap.omp.eu/) dedicated to the modeling of planetary ionospheres. Thanks to the development made for IRAP ionospheric model IPIM, it uses a unified description of the different ionized environments (presently Venus, Earth, Mars and Jupiter). The service provides a complete set of parameters characterizing these environments, including the concentration, velocities, temperatures, production rates of the different ions and electron heating rates. It is based on a modular approach allowing for selection of species, date of simulation and location. It is intended to be a support tool to data processing and analysis and we describe how simulation results can be used for such a purpose. The output format has been chosen to ease the interface with external data processing or vizualization tools, including online services. This web service is an open service which aims at providing users with the most relevant and consistent description of the couplings in planetary space environments and it will evolve in a way to increase user control on the simulation through a simplified Human-machine interface (HMI).

Kinetic model for stochastic heating in the INCA discharge

A novel electron heating mechanism based on periodically structured vortex fields induced in a plane was first proposed in 2014 (Czarnetzki and Tarnev 2014 Phys. Plasmas 21 123508). This theoretical concept has now been realized in an experiment which confirms efficient collisionless heating in such array structures (Ahr et al 2018 Plasma Sources Sci. Technol. 27 105010). The new concept is called ‘INductively Coupled Array’: INCA. Here, the physical mechanism behind the collisionless (stochastic) heating is investigated by two analytical models. Firstly, the electron heating rate in an array field structure with an exponential spatial decay of the field in the direction perpendicular to the plane is investigated by stochastically averaging single electron trajectories. The approach is similar to the Lieberman model for the classical stochastic heating in standard inductively coupled plasmas. This analysis shows that classical stochastic heating by thermal motion along the vertical direction makes a negligible contribution. However, there is a strong collisionless nonlocal heating effect in the plane. In conclusion, heating is nonlocal in the plane but local in the vertical direction. This insight allows a straightforward solution of the collisionless Boltzmann equation which not only confirms the results of the Lieberman model but provides also explicit expressions for the complex conductivity. Based on the conductivity an effective stochastic collision frequency, the complex damping coefficient and the related penetration of the field into the plasma is calculated. Finally, elastic collisions with neutral background atoms are included in the model and a condition for dominance of stochastic heating over Ohmic heating is derived.

Effects of HF frequency on plasma characteristics in dual-frequency helium discharge at atmospheric pressure by fluid modeling

On the basis of the fluid theory and the drift–diffusion approximation, a numerical model for dual-frequency atmospheric pressure helium discharge is established, in order to investigate the effects of the high frequency source (HF) on the characteristics of dual-frequency atmospheric pressure helium discharge. The numerical results showed that the electron heating rate increases with enhancing HF frequency, as well as the particles densities, electron dissipation rate, current density, net electron generation and bulk plasma region. Moreover, it is also observed that the efficient electron heating region moves when the HF frequency has been changed. The plasma parameters are not linear change with the HF frequency linearly increasing.

Alpha heating, isotopic mass, and fast ion effects in deuterium–tritium experiments

Alpha heating experiments in the Tokamak Fusion Test Reactor (TFTR) and in the Joint European Torus (JET) 1997 DTE1 campaign are reexamined. In TFTR supershots central electron heating of both deuterium only and deuterium–tritium supershots was dominated by thermal ion-electron heat transfer rate . The higher in deuterium–tritium supershots was mainly due to higher largely caused by isotopic mass effects of neutral beam—thermal ion heating. The thermal ion–electron heating dominated the electron heating in the center. The ratio of the predicted alpha to total electron heating rates is less than 0.30. Thus alpha heating (and possible favorable isotopic mass scaling of the thermal plasma) were too small to be measured reliably.The JET alpha heating Hot-Ion H-mode discharges had lower , and thus had lower and the deuterium–tritium DT discharges had higher than in TFTR. There were not enough comparable discharges to verify alpha heating. The high performance phases consisted of rampup to brief flattop durations. At equal times during the rampup phase central and were linearly correlated with the thermal hydrogenic isotopic mass which co-varied with beam ion pressure, the tritium fraction of neutral beam power, and the time delay to the first significant sawteeth which interrupted the increases.For both devices the expected alpha heating rate and the null hypothesis of no alpha heating are consistent with the measurements within the measurement and modeling uncertainties.

Manipulation of the plasma-dust layer in high-frequency discharge with an additional alternative phase

Abstract. In this paper, the properties of complex plasma and the manipulation of plasma-dust layer in high-frequency discharge with an additional alternative phase have been investigated. The computer simulation of the high-frequency capacitive discharge has been carried out under the influence of an additional alternative phase on the basis of the particle-in-cell and Monte Carlo (PIC / MCC) methods. The parameters describing the kinetic and transport properties (density and temperature of electrons, electron and ion heating rates) of complex plasma of high-frequency capacitive discharge have been obtained. The charging processes of dust particles, the forces acting on dust particles, as well as the equilibrium positions of the dust particles in the plasma have been studied. A method for manipulating particles of micro and nano sizes in a low-temperature complex plasma has been developed. The results have shown that the dust charge can be tuned by the properties of the excitation waveform and in connection with it we have suggested that the dust component of the plasma can be heated through a variation of the excitation waveforms via a mechanism similar to second-order Fermi acceleration. G M T Английский Испанский Итальянский Казахский Китайский Трад Китайский Упр Корейский Русский Турецкий Французский Английский Испанский Итальянский Казахский Китайский Трад Китайский Упр Корейский Русский Турецкий Французский Звуковая функция ограничена 200 символами Настройки : История : Обратная связь : Donate Закрыть

Turbulent heating due to magnetic reconnection

Dissipation of plasma turbulent energy is a phenomenon having significant implications for the heating of the solar corona and solar wind. While processes involving linear wave damping, stochastic heating, and reconnection have been postulated as contributors to heating mechanisms, the relative role that they play is not currently understood. In this manuscript, we establish a theoretical framework for applying reconnection heating predictions to turbulent systems. Kinetic particle-in-cell (PIC) simulations are used to study heating due to reconnection, and these results are then adapted to a turbulent medium. First, the factors controlling the heating of plasmas in reconnection exhausts are examined using laminar reconnection simulations; predictions for heating are determined which require only the plasma conditions just upstream of the reconnection diffusion region as input. The laminar predictions are then applied to PIC simulations of turbulence. Key assumptions are: (1) the plasma conditions just upstream of the diffusion region are consistent with Kolmogorov scaling of turbulent fluctuations at the ion inertial scale and (2) the statistics of the numbers of reconnecting x-lines do not vary significantly between the various turbulent simulations. We find that the reconnection theory predicts quite well the scaling of the ratio of ion to electron heating, in which the statistics of the turbulent reconnection sites are expected to roughly cancel. Separate ion and electron heating rates scale differently from the theory, however. This suggests that the statistics of the turbulent reconnection (e.g., number of x-lines, percentage of x-lines reconnecting) is playing an important role in determining the ion and electron heating.

Kinetic Alfvén Turbulence: Electron and Ion Heating by Particle-in-cell Simulations

Abstract Three-dimensional particle-in-cell simulations of the forward cascade of decaying kinetic Alfvén turbulence have been carried out as an initial-value problem on a collisionless, homogeneous, magnetized, electron–ion plasma model with and m i/m e = 100, where subscripts e and i represent electrons and ions, respectively. Initial anisotropic narrowband spectra of relatively long-wavelength modes with approximately gyrotropic distributions in undergo a forward cascade to broadband spectra of magnetic fluctuations at shorter wavelengths. Maximum electron and ion heating rates are computed as functions of the initial fluctuating magnetic field energy density on the range . In contrast to dissipation by whistler turbulence, the maximum ion heating rate due to kinetic Alfvén turbulence is substantially greater than the maximum electron heating rate. Furthermore, ion heating as well as electron heating due to kinetic Alfvén turbulence scale approximately with ε o. Finally, electron heating leads to anisotropies of the type , where the parallel and perpendicular symbols refer to directions parallel and perpendicular, respectively, to the background magnetic field, whereas the heated ions remain relatively isotropic. This implies that, for the range of ε o values considered, the Landau wave–particle resonance is a likely heating mechanism for the electrons and may also contribute to ion heating.