Plasma Conditions Research Articles

Beam‐Driven Electron Cyclotron Harmonic and Electron Acoustic Waves as Seen in Particle‐In‐Cell Simulations

AbstractRecent study has demonstrated that electron cyclotron harmonic (ECH) waves can be excited by a low energy electron beam. Such waves propagate at moderately oblique wave normal angles (∼70°). The potential effects of beam‐driven ECH waves on electron dynamics in Earth's plasma sheet is not known. Using two‐dimensional Darwin particle‐in‐cell simulations with initial electron distributions that represent typical plasma conditions in the plasma sheet, we explore the excitation and saturation of such beam‐driven ECH waves. Both ECH and electron acoustic waves are excited in the simulation and propagate at oblique wave normal angles. Compared with the electron acoustic waves, ECH waves grow much faster and have more intense saturation amplitudes. Cold, stationary electrons are first accelerated by ECH waves through cyclotron resonance and then accelerated in the parallel direction by both the ECH and electron acoustic waves through Landau resonance. Beam electrons, on the other hand, are decelerated in the parallel direction and scattered to larger pitch angles. The relaxation of the electron beam and the continuous heating of the cold electrons contribute to ECH wave saturation and suppress the excitation of electron acoustic waves. When the ratio of plasma to electron cyclotron frequency ωpe/ωce increases, the ECH wave amplitude increases while the electron acoustic wave amplitude decreases. Our work reveals the importance of ECH and electron acoustic waves in reshaping sub‐thermal electron distributions and improves our understanding on the potential effects of wave‐particle interactions in trapping ionospheric electron outflows and forming anisotropic (field‐aligned) electron distributions in the plasma sheet.

Enhancing particle string detection in electrorheological plasmas using asymmetrical kernel convolutional networks

Under different plasma conditions and electric fields in a complex plasma the plasma particles organize themselves in a string-like or chain-like manner. A phase transition from string-like to an isotropic particle distribution is observed at different electrical conditions. The streaming of charged ions around plasma particles with the surrounding electric field gives the plasma its electrorheological properties. The visibility of individual particles in a complex plasma opens up the opportunity to examine properties and phase transitions of such electrorheological fluids in detail. Because of the limited one-dimensional symmetry, determining the configuration of a particle and recognizing strings in particle distributions is not always straightforward. Several approaches have already been used to analyse particle clouds while either considering each particle locally or considering the particle cloud as a whole without providing information about single particle configurations. This paper presents a new machine learning approach that takes advantage of particle distributions over the entire particle cloud and detects all string-like particles at once, using a convolutional neural network in form of an encoder-decoder network with asymmetric kernel convolutions. This not only enhances the result quality but also accelerates the evaluation process, possibly enabling real-time analyses on electrorheological phase transitions, while achieving an accuracy of over 95% on manually labelled data.

Helium plasma irradiation on Nickel: Nanostructure formation and electrochemical characteristics

Nanotechnology offers new avenues for the design, fabrication, and application of novel materials. Helium plasma exposure is a technique that can be used to fabricate self-supported metallic nanostructures. In this work, we explore the plasma irradiation conditions for fabricating various morphologies on planar nickel surfaces, and evaluate the electrochemical performance of these surfaces for oxygen evolution reaction (OER) in alkaline media. The preferential growth towards certain morphologies such as nano-pillars, nano-blocks, and micro-structures, is found to be primarily influenced by the applied plasma conditions and two counteracting processes of sputtering and annealing. The plasma treatment increased the electrochemical surface area of the modified samples by approximately 3 to 4 times as compared to the planar/unmodified surfaces, along with an increase in the OER performance for all morphologies. However, in addition to the increased surface area, the electrochemical performance was found to be dependent on the shape, size and thickness of the nano/micro-features. Moving ahead, the ability of this technique to achieve control over the feature size along with its effectiveness for a broad range of metals offers new routes for nanostructuring and functionalization of emerging materials.

Preparation of vertical graphene by PECVD with different plasma conditions

Vertical growth of graphene thin films was achieved on Si (100) substrate employing the sputtering technique. Physical-chemical properties of graphene thin films were examined at annealing temperatures from 500 to 780 °C and flowrate ratios of Ar and C2H2 working gases. The effect of temperature on the growth of graphene thin film, surface morphology, microstructure properties, and chemical state were investigated systematically. The formed graphene thin films were characterized and analyzed using different techniques such as Raman spectroscopy, field emission- and cross-sectional-scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The graphene thin films on the Si substrate exhibited the better growth at the 700 °C and 30:15 (Ar:C2H2) flowrate ratio. Results of Raman spectroscopy showed that the graphene thin films have graphitic structure with crystallite size in the range of 10 to 23 nm. Surface morphology exhibited a wall-like structure with a sheet shape. The CS-SEM images indicated columnar growth of films perpendicular to the film plane. Analysis of the chemical states of C 1 s and O 1 s indicated chemical defects in the graphene thin films, evidenced by the presence of lattice oxygen and non-lattice oxygen ions.

Estimated electric conductivities of thermal plasma for air-fuel combustion and oxy-fuel combustion with potassium or cesium seeding

A complete model for estimating the electric conductivity of combustion product gases, with added cesium (Cs) or potassium (K) vapor for ionization, is presented. Neutral carrier gases serve as the bulk fluid that carries the seed material, as well as the electrons generated by the partial thermal (equilibrium) ionization of the seed alkali metal. The model accounts for electron-neutral scattering, as well as electron-ion and electron-electron scattering. The model is tested through comparison with published data. The model is aimed at being utilized for the plasma within magnetohydrodynamic (MHD) channels, where direct power extraction from passing electrically conducting plasma gas enables electric power generation.The thermal ionization model is then used to estimate the electric conductivity of seeded combustion gases under complete combustion of three selected fuels, namely: hydrogen (H2), methane (CH4), and carbon (C). For each of these three fuels, two options for the oxidizer were applied, namely: air (21 % molecular oxygen, 79 % molecular nitrogen by mole), and pure oxygen (oxy-combustion). Two types of seeds (with 1 % mole fraction, based on the composition before ionization) were also applied for each of the six combinations of (fuel-oxidizer), leading to a total of 12 different MHD plasma cases. For each of these cases, the electric conductivity was computed for a range of temperatures from 2000 K to 3000 K.The smallest estimated electric conductivity was 0.35 S/m for oxy-hydrogen combustion at 2000 K, with potassium seeding. The largest estimated electric conductivity was 180.30 S/m for oxy-carbon combustion at 3000 K, with cesium seeding. At 2000 K, replacing potassium with cesium causes a gain in the electric conductivity by a multiplicative gain factor of about 3.6 regardless of the fuel and oxidizer. This gain factor declines to between 1.77 and 2.07 at 3000 K.Based on the findings of this research study, the four analyzed factors to increase the electric conductivity of MHD plasma can be listed by their significance (descending order) as (1) type of additive seed type (cesium is better than potassium), (2) temperature (the higher the better), (3) carbon-to-hydrogen ratio of the fuel (the higher the better), and finally (4) the oxidizer type (air is generally better than pure oxygen).The relative size of the two electric conductivity components (due to neutrals scattering and Coulomb scattering) at various plasma conditions are discussed, and a threshold of 10−5 (0.001 %) electrons mole fraction is suggested to safely neglect Coulomb scattering.

Obtaining Plasma–Dust Clouds from Meteoritic Matter, its Analogs and Simulants of Lunar Regolith Using Microwave Discharge

—In the experiment, plasma–dust clouds were obtained from the substance of the Tsarev meteorite, a simulant of lunar regolith LMS-1D and ilmenite concentrate using a microwave discharge in powder media. For each of the samples, the dynamics of the development of the discharge and the formation of a plasma–dust cloud with subsequent relaxation after the end of the microwave pulse were recorded. From the emission spectra of the plasma and the surface of a solid body, the temperatures of the gas, electrons and surface were determined. A comparison of the phase and elemental composition of the initial samples and samples after exposure to plasma showed that there is no significant change in the composition. However, scanning electron microscopy results clearly indicate spheroidization of the original angular and irregularly shaped particles. The appearance of spherical particles is also observed, the dimensions of which are larger than the linear dimensions of the particles in the original sample. The results obtained indicate the possibility of using such experiments to study chemical and plasma-chemical processes of synthesis and modification of substances under conditions of plasma–dust clouds encountered in space phenomena.

Numerical and experimental study of supersonically expanding argon plasma using a micrometer hollow cathode discharge

Pulsed discharge nozzles (PDNs) have been successfully used for decades to produce rotationally cold (Trot ∼ 20 K) radicals and ions of astrophysical interest and to characterize these species spectroscopically. In this work, an evolution of the PDN, the piezostack pulsed discharge nozzle (P2DN), is used for the first time to investigate the characteristics of the still poorly understood supersonic plasma expansion. The P2DN allows for a better control of the reservoir pressure of which an accurate measurement is required to characterize the plasma expansion. This new source, thus, gives the opportunity to further optimize the plasma conditions and extend its use to new target species. The spatial distribution of an argon plasma and the effect of the supersonic flow for different pressures are studied by combining a two-dimensional extended fluid model (extFM) and a direct simulation Monte Carlo (DSMC) method. The combined simulation is validated with experimental results obtained through emission spectroscopy associated with a group-code collisional-radiative model to retrieve the plasma parameters. The validated numerical approach (DSMC-extFM) allows for an accurate characterization of the plasma structure in our typical experimental conditions (a reservoir pressure ranging from 90 to 905 mbar). Thus, this simulation will be used in future studies to improve the plasma conditions to favor the synthesis of (transient) hydrocarbon species as found in space, by seeding the argon gas with a suitable precursor, such as acetylene.

Optimization of Ion Beam-Assisted Deposition Process for Y<sub>2</sub>O<sub>3</sub> Film to Enhance Plasma Resistance

A ceramic-based plasma etcher window (Lid) requires robust resistance to plasma, especially when exposed to harsh fluorine-based plasma conditions. In this study, a Y<sub>2</sub>O<sub>4</sub> film was deposited using e-beam evaporation with ion beam-assisted deposition (IBAD), and the physical properties of the IBAD-based Y<sub>2</sub>O<sub>4</sub> coating film were thoroughly examined to enhance the mechanical and chemical resistance of the ceramic part, including the Y<sub>2</sub>O<sub>4</sub> film, against etching plasma. The hardness and surface morphology of the IBADbased Y<sub>2</sub>O<sub>4</sub> could be precisely controlled by various deposition processing parameters, such as beam voltage, beam current, and Ar/O2 gas ratio. Following the IBAD deposition of the Y<sub>2</sub>O<sub>4</sub> film, a plasma etching process (Ar/CF<sub>4</sub> mixture gases with 150 W RF power for 60 minutes) was applied to evaluate the plasma resistance of the deposited Y<sub>2</sub>O<sub>4</sub> coating film. The surface morphology characteristics of the Y<sub>2</sub>O<sub>4</sub> films were compared using atomic force microscopy, and their grain size was studied through scanning electron microscopy image analysis. Furthermore, a nanoindenter was used to determine the hardness of the Y<sub>2</sub>O<sub>4</sub> film. These results suggest that optimizing the IBAD coating process requires an in-depth study that fully considers the correlation between deposition processing parameters and physical properties. This optimization can be instrumental for enhancing the durability of the ceramic part.

Development and initial evaluation of a combustion-based sample introduction system for direct isotopic analysis of mercury in solid samples via multi-collector ICP-mass spectrometry

High-precision isotopic analysis of mercury (Hg) using multi-collector ICP-mass spectrometry (MC-ICP-MS) is a powerful method for obtaining insight into the sources, pathways and sinks of this toxic metal. Modification of a commercially available mercury analyzer (Teledyne Leeman Labs, Hydra IIc – originally designed for quantification of Hg through sample combustion, collection of the Hg vapor on a gold amalgamator, subsequent controlled release of Hg and detection using cold vapor atomic absorption spectrometry CVAAS) enabled the system to be used for the direct high-precision Hg isotopic analysis of solid samples using MC-ICP-MS – i.e., without previous sample digestion and subsequent dilution. The changes made to the mercury analyzer did not compromise its (simultaneous) use for Hg quantification via CVAAS. The Hg vapor was mixed with a Tl-containing aerosol produced via pneumatic nebulization, creating wet plasma conditions, and enabling the use of Tl as an internal standard for correction of instrumental mass discrimination. Accurate and precise (0.10 ‰ 2SD, δ202Hg, n = 5) results were obtained for an in-house standard solution of Hg (20 ng Hg sample intake). Initial validation relied on the successful analysis of two solid certified reference materials of biological origin (BCR CRM 464 Tuna fish and NRC-CNRC TORT-3 Lobster hepatopancreas). It was shown that instrumental mass discrimination can be adequately corrected for by relying on the use of an aqueous Hg standard solution (NIST SRM 3133), without the need of matrix-matching. The novel setup developed thus allows for direct high-precision isotopic analysis of Hg in solid samples, thus enhancing the sample throughput. It is also suited for samples for which low amounts are available only and/or that are characterized by low Hg concentrations.

Review of the second charged-particle transport coefficient code comparison workshop

We report the results of the second charged-particle transport coefficient code comparison workshop, which was held in Livermore, California on 24–27 July 2023. This workshop gathered theoretical, computational, and experimental scientists to assess the state of computational and experimental techniques for understanding charged-particle transport coefficients relevant to high-energy-density plasma science. Data for electronic and ionic transport coefficients, namely, the direct current electrical conductivity, electron thermal conductivity, ion shear viscosity, and ion thermal conductivity were computed and compared for multiple plasma conditions. Additional comparisons were carried out for electron–ion properties such as the electron–ion equilibration time and alpha particle stopping power. Overall, 39 participants submitted calculated results from 18 independent approaches, spanning methods from parameterized semi-empirical models to time-dependent density functional theory. In the cases studied here, we find significant differences—several orders of magnitude—between approaches, particularly at lower temperatures, and smaller differences—roughly a factor of five—among first-principles models. We investigate the origins of these differences through comparisons of underlying predictions of ionic and electronic structure. The results of this workshop help to identify plasma conditions where computationally inexpensive approaches are accurate, where computationally expensive models are required, and where experimental measurements will have high impact.

Theoretical and global simulation analysis of collisional microtearing modes

Microtearing modes (MTMs) are suggested as a candidate for anomalous thermal transport in tokamak H-mode discharges. This study investigates MTMs in tokamak plasmas, employing simulations in the BOUT++ framework. It simplifies and linearizes the governing equations in detailed linear simulations. The study meticulously evaluates various conductivity models under diverse plasma conditions and collision regimes. The research thoroughly assesses different conductivity models across a range of plasma conditions and collision regimes. A unified dispersion relation that includes both MTM and Drift-Alfvén Wave (DAW) instabilities is derived, showing that DAW and MTM instabilities occur at varying distances from the rational surface. Specifically, MTMs become unstable near the rational surface but stabilize farther away, while drift-Alfvén instability appears farther from the rational surface. The study also re-derives MTM dispersion relations using Ohm's law and the vorticity equation, providing a thorough analysis of electromagnetic and electrostatic interactions in tokamaks. Global simulations demonstrate an inverse correlation between MTM growth rates and collisionality, and a direct correlation with temperature gradients. The nonalignment of the rational surface with the peak ω*e stabilizes the MTMs. Nonlinear simulations highlight electron temperature relaxation as the primary saturation mechanism for MTMs, with magnetic flutter identified as the dominant mode of electron thermal transport.

Producing two-dimensional dust clouds and clusters using a movable electrode for complex plasma and fundamental physics experiments.

We report a Bidirectional Electrode Control Arm Assembly (BECAA) for precisely manipulating dust clouds levitated above the powered electrode in RF plasmas. The reported techniques allow the creation of perfectly 2D dust layers by eliminating off-plane particles by moving the electrode from outside the plasma chamber without altering the plasma conditions. The tilting and moving of electrodes using BECAA also allows the precise and repeatable elimination of dust particles one by one to achieve any desired number of grains N without trial and error. Simultaneously acquired top and side view images of dust clusters show that they are perfectly planar or 2D. A demonstration of clusters with N = 1-28 without changing the plasma conditions is presented to show the utility of BECAA for complex plasma and statistical physics experimental design. Demonstration videos and 3D printable part files are available for easy reproduction and adaptation of this new method to repeatably produce 2D clusters in existing RF plasma chambers.

Charged particle transport coefficient challenges in high energy density plasmas

High energy density physics (HEDP) and inertial confinement fusion (ICF) research typically relies on computational modeling using radiation-hydrodynamics codes in order to design experiments and understand their results. These tools, in turn, rely on numerous charged particle transport and relaxation coefficients to account for laser energy absorption, viscous dissipation, mass transport, thermal conduction, electrical conduction, non-local ion (including charged fusion product) transport, non-local electron transport, magnetohydrodynamics, multi-ion-species thermalization, and electron-ion equilibration. In many situations, these coefficients couple to other physics, such as imposed or self-generated magnetic fields. Furthermore, how these coefficients combine are sensitive to plasma conditions as well as how materials are distributed within a computational cell. Uncertainties in these coefficients and how they couple to other physics could explain many of the discrepancies between simulation predictions and experimental results that persist in even the most detailed calculations. This paper reviews the challenges faced by radiation-hydrodynamics in predicting the results of HEDP and ICF experiments with regard to these and other physics models typically included in simulation codes.

Time-resolved measurement of optical emission line profiles from electron cyclotron resonance ion source plasma

Optical emission spectroscopy provides a non-invasive method to probe the properties of hot and highly charged magnetically confined plasmas. The optical emission line profiles enable, for example, to identify the different species and characterize the relative population densities and temperatures of the ions and neutrals forming the plasma. The feasibility of this approach has been demonstrated at the University of Jyväskylä accelerator laboratory by measuring the light emitted by Electron Cyclotron Resonance Ion Source (ECRIS) plasma with a high-resolution spectrometer setup POSSU (Plasma Optical SpectroScopy Unit). In these previous studies, the emission line profiles were measured by scanning the desired wavelength range by rotating the diffraction grating of the spectrometer. This process is slow compared to many interesting plasma phenomena, thus limiting the applicability of the setup. Recently, POSSU has been upgraded by changing the light sensor from a photomultiplier tube to a position-sensitive imaging sensor. As a result, it is possible to measure simultaneously a 1 - 2 nm wavelength range, with a spectral resolution in the order of picometers, without moving the grating. This enables a time-resolved study of the optical emission line profiles. By turning the grating, the measured wavelength region can be chosen between 370 nm and 870 nm, which covers the visible light spectrum. The time-evolution of optical emission line profiles emitted from the JYFL 14 GHz ECRIS plasma, during shifting plasma conditions induced by changing the gas balance, has been measured to demonstrate this new capability. The time-evolution of temperatures and emission intensities of selected ion species, correlated with extracted ion beam currents, are presented.

Ring momentum distributions as a general feature of Vlasov dynamics in the synchrotron dominated regime

We study how radiation reaction leads plasmas initially in kinetic equilibrium to develop features in momentum space, such as anisotropies and population inversion, resulting in a ring-shaped momentum distribution that can drive kinetic instabilities. We employ the Landau–Lifshiftz radiation reaction model for a plasma in a strong magnetic field, and we obtain the necessary condition for the development of population inversion; we show that isotropic Maxwellian and Maxwell–Jüttner plasmas, with thermal temperature T>mec2/3, will develop a ring-like momentum distribution. The timescales and features for forming ring-shaped momentum distributions, the effect of collisions, and non-uniform magnetic fields are discussed and compared with typical astrophysical and laboratory plasmas parameters. Our results show the pervasiveness of ring-like momentum distribution functions in synchrotron dominated plasma conditions.

Characterization of a filamentary discharge ignited in a gliding arc plasmatron operated in nitrogen flow

A gliding arc plasmatron (GAP) is a promising warm plasma source for the use in gas conversion applications but lacks an understanding of the plasma dynamics. In this paper, the gliding arc plasma conditions of a GAP operated with nitrogen flow (10 slm) are characterized using optical emission spectroscopy (OES) and numerical simulation. A simultaneously two-wavelength OES method and Abel inversion of the measured images with a spatial resolution of 19.6 μm are applied. The collisional radiative model used in this study includes Coulomb collisions of electrons. An iterative method of plasma parameter determination is applied. The determined values of the electric field up to 49 Td and electron density up to 2.5∙1015 cm−3 fit well to the plasma parameters received with different diagnostics methods in comparable plasma sources. Additionally, the electric current, which is calculated using the determined reduced electric field and electron density, is compared with the measured one.

Narrowly Banded Spectra with Peak Frequency around 1 GHz of FRB 20201124A: Implications for Energy Function and Radiation Physics

The radiation physics of fast radio bursts (FRBs) remains an open question. Current observations have discovered that narrowly banded bursts of FRB 20201124A are active in 0.4–2 GHz, and their spectral peak frequency ( νpobs ) is mostly toward ∼1 GHz. Utilizing a sample of 1268 bursts of FRB 20201124A detected with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we show that the 1σ spectral regime of 71.4% of the events (in-band bursts) is within the FAST bandpass. The intrinsic burst energies ( EBWeobs ) and spectral widths ( σsobs ) are well measured by fitting the spectral profile with a Gaussian function. The derived EBWeobs and σsobs distributions are lognormal and centered at logEBWeobs/erg=37.2(σ=0.76) and logσsobs/GHz=−1.16(σ=0.17) . Our Monte Carlo simulation analysis infers its intrinsic ν p distribution as a normal function centered at ν p,c = 1.16 GHz (σ = 0.22) and its intrinsic energy function as Φ(E)∝E−0.60e−E/Ec with E c = 9.49 × 1037 erg. We compare these results with that of typical repeating FRBs 20121102A and 20190520B, which are active over a broad frequency range at several specific frequencies, and discuss possible observational biases on the estimation of the event rate and energy function. Based on these results, we argue that FRB 20201124A likely occurs in a fine-tuned plasma for maser radiation at a narrow frequency range, while FRB 20121102A and FRB 20190520B could involve clumpy plasma conditions that make maser emission around several specific frequencies in a broad range.

Nonlinear dynamics of the reversed shear Alfvén eigenmode in burning plasmas

In a tokamak fusion reactor operated at steady state, the equilibrium magnetic field is likely to have reversed shear in the core region, as the noninductive bootstrap current profile generally peaks off-axis. The reversed shear Alfvén eigenmode (RSAE) as a unique branch of the shear Alfvén wave in this equilibrium, can exist with a broad spectrum in wavenumber and frequency, and be resonantly driven unstable by energetic particles (EP). After briefly discussing the RSAE linear properties in burning plasma condition, we review several key topics of the nonlinear dynamics for the RSAE through both wave-EP resonance and wave-wave coupling channels, and illustrate their potentially important role in reactor-scale fusion plasmas. By means of simplified hybrid MHD-kinetic simulations, the RSAEs are shown to have typically broad phase space resonance structure with both circulating and trapped EP, as results of weak/vanishing magnetic shear and relatively low frequency. Through the route of wave-EP nonlinearity, the dominant saturation mechanism is mainly due to the transported resonant EP radially decoupling with the localized RSAE mode structure, and the resultant EP transport generally has a convective feature. The saturated RSAEs also undergo various nonlinear couplings with other collective oscillations. Two typical routes as parametric decay and modulational instability are studied using nonlinear gyrokinetic theory, and applied to the scenario of spontaneous excitation by a finite amplitude pump RSAE. Multiple RSAEs could naturally couple and induce the spectral energy cascade into a low frequency Alfvénic mode, which may effectively transfer the EP energy to fuel ions via collisionless Landau damping. Moreover, zero frequency zonal field structure could be spontaneously excited by modulation of the pump RSAE envelope, and may also lead to saturation of the pump RSAE by both scattering into stable domain and local distortion of the continuum structure.

Plasma emission spectroscopy and optical properties of reactive-sputtered silicon oxynitride films

Silicon oxynitride (SiO x N y ) thin films were synthesized via reactive direct current magnetron sputtering under different reactive gas mass flow ratios (O2:N2) and discharge powers. The process was monitored by optical emission spectroscopy (OES), while spectroscopic ellipsometry was used to characterize the optical properties of the thin films and deposition rates. In this work, the plasma generated under different deposition parameters is analyzed by monitoring the emission lines of different species (Si I, Ar I, O2, and N2) and these results are then correlated with the corresponding target poisoning process and the optical properties of the grown thin films. According to the spectral analysis, the emission lines proved to be sensitive to the synthesis process as it was possible to differentiate deposition variations when other parameters remained unchanged. Furthermore, similar plasma conditions determined via the emission of different species were found to produce consistent thin film optical properties and vice versa. OES showed to be an effective method of monitoring and controlling the deposition of SiO x N y thin films with specific compositions.

Large Amplitude Whistler Waves in Earth's Plasmasphere and Plasmaspheric Plumes

AbstractWhistler mode waves in the plasmasphere and plumes drive significant losses of energetic electrons from the Earth's radiation belts into the upper atmosphere. In this study, we conducted a survey of amplitude‐dependent whistler wave properties and analyzed their associated background plasma conditions and electron fluxes in the plasmasphere and plumes. Our findings indicate that extremely large amplitude (>400 pT) whistler waves (a) tend to occur at L > 4 over the midnight‐dawn‐noon sectors and have small wave normal angles; (b) are more likely to occur during active geomagnetic conditions associated with higher fluxes of anisotropic electrons at 10 s keV energies; and (c) tend to occur at higher latitudes up to 20° with increasing amplitude. These results suggest that extremely large amplitude whistler waves in the plasmasphere and plumes could be generated locally by injected electrons during substorms and further amplified when propagating to higher latitudes.