Plasma Transport Research Articles

Surrogate model of turbulent transport in fusion plasmas using machine learning

Abstract The advent of machine learning (ML) has revolutionized the research of plasma confinement, offering new avenues for exploration. It enables the construction of models that effectively streamline the simulation process. While previous first-principles simulations have provided physics-based transport information, they have been inadequate fast for real-time applications or plasma control. In order to address this challenge, we introduce SExFC, a surrogate model based on the Gyro-Landau Extended Fluid Code (ExFC). An approach of physics-based database construction is detailed, as well the validity is illustrated. Through harnessing the power of ML, SExFC offers the capability to deliver rapid and precise predictions, facilitating real-time applications and enhancing plasma control. The proposed model integrates the recurrent neural network (RNN) algorithm, specifically leveraging the Gated Recurrent Unit (GRU) for iterative prediction of flux evolutions based on radial profiles. Therefore, the SExFC model has the potential to enable rapid and physics-based predictions that can be seamlessly integrated into future real-time plasma control systems.

Effects of discharge parameters on plasma acceleration and transmission characteristics of a coaxial gun operated in gas-prefilled mode

The effects of discharge parameters on the discharge process and plasma transport characteristics of a coaxial gun in the gas-prefilled mode are studied. The plasma optical intensity and ejection velocity are measured by photodiodes, the optical emission spectrum is taken by a spectroscopic system, and the plasma evolution in the transport process is captured by a high-speed camera. The plasma acceleration characteristics under different discharge parameters show that the velocity and electron density of the ejection plasma are mainly determined by the pre-filled pressure and discharge current, which is consistent with the snowplow model. The kinetic energy of ejection plasma can be significantly increased by reducing the outer loop inductance, which is conducive to increasing the energy utilization efficiency. The time-varying images of plasma radiation and the plasma density at different transport locations illuminate the transmission characteristics of coaxial gun discharge plasma. The results show that the snowplow effect continues to play a role in the plasma transport process, and the plasma accumulation is induced by the combination of shock wave compression. The current-driven magneto hydrodynamics instability occurs during the transport process, and the luminous signal of the plasma current sheet oscillates periodically. In addition, the plasma impact effect is obvious and the gas retarding effect is enhanced with the increase in the gas pressure. These results give us a more comprehensive view of the coaxial gun discharge process and plasma transport and provide a certain reference for optimizing the parameters selection and physical design of coaxial gun discharge plasma characteristics.

Model-predictive kinetic control with data-driven models on EAST

Abstract In this work, model-predictive control (MPC) was combined for the first time with singular perturbation theory, and an original plasma kinetic control method based on extremely simple data-driven models and a two-time-scale MPC algorithm has been developed. A comprehensive review is presented in this paper. Slow and fast semi-empirical models are identified from data, by considering the fast kinetic plasma dynamics as a singular perturbation of a quasi-static equilibrium, which itself is governed, on the slow time scale, by the flux diffusion equation. This control technique takes advantage of the large ratio between the time scales involved in magnetic and kinetic plasma transport. It is applied here to the simultaneous control of the safety factor profile, q(x), and of several kinetic variables, such as the poloidal beta parameter, βp, and the internal inductance parameter, li, on the EAST tokamak. In the experiments, the available control actuators were lower hybrid current drive (LHCD) and co-current neutral beam injection (NBI) from different sources. Ion cyclotron resonant heating (ICRH) and electron cyclotron resonant heating (ECRH) are used as additional actuators in control simulations. In the controller design, an observer provides, in real time, an estimate of the system states and of the mismatch between measured and predicted outputs, which ensures robustness to model errors and offset-free control. A number of control applications are described in the paper, either in nonlinear simulations with EAST-like parameters or in real experiments on EAST. Various controller configurations were tested, with up to three controlled variables chosen among q0 = q(x=0), q1 = q(x=0.5), βp and li. Both the extensive nonlinear simulations and the experiments described in this paper have demonstrated the relevance of combining model-predictive control, data-driven models and singular perturbation methods for plasma kinetic control.

Biological evaluation of sophoridine by interaction with plasma transport protein and protective effects in cardiomyocytes

Numerous studies have demonstrated the protective benefits of sophoridine, a bioactive alkaloid, on cell damage. However, its primary biological properties such as interaction with plasma protein, which serves as the primary drug carrier, and its cardioprotective properties are still unknown. In the present study, we aimed to analyze the binding characteristics of sophoridine with alpha-2-macroglobulin (α2M) by spectroscopic and theoretical studies. Then, the cardioprotective effects of sophoridine on myocardial ischemia/reperfusion (MI/R) injury in vitro were investigated using H9c2 cardiomyocytes. The results reveal that one molecule of sophoridine favorably binds to one molecule of α2M dominantly through interaction with hydrophobic amino acid residues (VAL758, PHE735, PHE735, and TRP739). Also, sophoridine leads to partial changes in the structure of this carrier protein in the vicinity of TRP739 residue. Cellular assays exhibit that sophoridine recovered cell viability, membrane leakage, and apoptosis induced by MI/R injury. It was detected that sophoridine could mitigate the oxidative stress and intrinsic apoptosis pathway through regulation of Bax, Bcl-2, and caspase. ELISA analysis also exhibits that sophoridine upregulates phosphorylation of Akt and PI3K in H9c2 cells. Our findings suggest that sophoridine could show favorable plasma protein interaction and promising cardioprotection against MI/R injury mediated by the upregulation of PI3K/AKT signaling pathway.

Poloidal magnetic field reconstruction by laser-driven ion-beam trace probe in spherical tokamak

The poloidal magnetic field ( plays a critical role in plasma equilibrium, confinement and transport of magnetic confinement devices. Multiple diagnostic methods are needed to complement each other to obtain a more accurate profile. Recently, the laser-driven ion-beam trace probe (LITP) has been proposed as a promising tool for diagnosing and radial electric field ( ) profiles in tokamaks [Yang X Y et al 2014 Rev. Sci. Instrum. 85 11E429]. The spherical tokamak (ST) is a promising compact device with high plasma beta and naturally large elongation. However, when applying LITP to diagnosing in STs, the larger invalidates the linear reconstruction relationship for conventional tokamaks, necessitating the development of a nonlinear reconstruction principle tailored to STs. This novel approach employs an iterative reconstruction method based on Newton’s method to solve the nonlinear equation. Subsequently, a simulation model to reconstruct the profile of STs is developed and the experimental setup of LITP is designed for EXL-50, a middle-sized ST. Simulation results of the reconstruction show that the relative errors of reconstruction are mostly below 5%. Moreover, even with 5 mm measurement error on beam traces or 1 cm flux surface shape error, the average relative error of reconstruction remains below 15%, initially demonstrating the robustness of LITP in diagnosing profiles in STs.

Charged-particle transport in high energy density plasmas

This Special Topic Collection grew out of two gatherings of researchers active in the high energy density (HED) physics community: a mini-conference on charged-particle transport in HED plasma held during the 64th annual meeting of the American Physical Society's Division of Plasma Physics (Spokane, WA, November 2022) and a dedicated charged-particle transport coefficient code comparison workshop (Livermore, CA, July 2023). These gatherings provided opportunities for theoretical, computational, and experimental researchers to discuss the state of the field, including current capabilities and methods, needs of hydrodynamic simulations, and frontiers for future research. This special issue collects a total of 13 research and review articles on charged-particle transport in HED plasmas.

Electron Pitch Angle Distributions in Magnetotail Tailward Flows

AbstractElectron pitch angle distributions (PADs) are crucial to revealing electron acceleration and heating in geospace. The electron PADs in the Earth's magnetotail have been widely studied by statistical or case analysis. However, the statistical features of electron PADs in tailward flows are still unclear. We survey data from the Magnetospheric Multiscale (MMS) satellite to statistically investigate electron PADs in tailward flows in the Earth's magnetotail for the first time. We find that for most (66.3%) tailward flows, electrons with energy from 0.1 to 30 keV are mainly field‐aligned. The PADs of suprathermal (>2 keV) electrons in a part of tailward flows (26.3%) are mostly isotropic. Additionally, the perpendicular‐dominated PADs of suprathermal electrons only exist in a few (7.4%) tailward flows. According to the different dominant PADs of suprathermal electrons, the tailward flows are classified into three types: field‐aligned‐dominated type, isotropic‐dominated type and perpendicular‐dominated type flows. The dependence of electron PADs on plasma environmental parameters is investigated in these three types of flows. For field‐aligned‐dominated type flows, the field‐aligned anisotropy decreases toward the central plasma sheet (CPS) and with the increase of the energy. In addition, it is found that the field‐aligned anisotropy in the field‐aligned‐dominated tailward flows reduces noticeably when the |Vix| exceeds 800 km/s. In isotropic‐dominated type flows, the field‐aligned anisotropy of electrons with energy ≥10 keV also shows a slight decreasing trend toward the CPS. For perpendicular‐dominated type flows, the perpendicular anisotropy exhibits two non‐monotonic processes, initially increasing and then decreasing with the increase of distance from the CPS; while becomes more evident for higher energy electrons. Our statistical results indicate that in tailward flows, electron anisotropy depends on the distance from the CPS, energy and plasma flow velocity. Tailward flows are associated with the transport of plasma toward the distant tail, and the statistical analysis of electron PADs in these flows can improve our understanding of the related electron dynamics in the magnetotail.

Multifaceted Analysis of Bempedoic Acid Binding to Subdomain IIA of Human Serum Albumin

The molecular association between bempedoic acid (BAC) and the major blood plasma transporter, human serum albumin (HSA), was investigated using molecular docking, molecular dynamics (MD) simulation, isothermal titration calorimetry (ITC), atomic force microscopy (AFM), and spectroscopic techniques. During the docking and MD simulation investigations, it was observed that BAC interacted with subdomain IIA (Site I) of HSA through hydrogen bonds and hydrophobic interactions. This interaction ensured the stability of the complex throughout the duration of 100 ns. The observed enhancement in the fluorescence intensity of HSA after BAC inclusion and the swelling of HSA generated by BAC in the AFM data also suggested the formation of a complex between BAC and HSA. The BAC demonstrated a moderate affinity towards HSA, with a binding constant (Ka) of 1.21 ± 0.05 × 105 M−1 at 300 K. Notable modifications in the secondary and tertiary structures of the protein, as well as changes in the protein's Tyr/Trp surroundings, were observed using circular dichroism and three-dimensional fluorescence spectra when the protein was attached to BAC. Insightful information regarding molecular interactions that regulate the stability of the BAC-HSA complex is provided by these investigations.

Nup210 Promotes Colorectal Cancer Progression by Regulating Nuclear Plasma Transport

The nuclear pore complex (NPC) regulates nucleoplasmic transport, transcription, and genomic integrity in eukaryotic cells. However, little is known about how NPC works in cancer. In this study, we investigated the role of the nuclear pore protein 210 (Nucleoporin 210, Nup210) in colorectal cancer (CRC). Bioinformatics analysis revealed that the expression of Nup210 was increased in CRC and was associated with poor patient prognosis, but it was not a statistically significant independent prognostic factor. Moreover, knockdown of Nup210 in CRC cells inhibited the proliferation, invasion, and metastasis of CRC cells in vivo and in vitro. Additionally, nuclear size and nuclear plasma material transport capacity decreased along with the number and density of NPCs on the surface of CRC cells when Nup210 expression was inhibited. Furthermore, Nup210 required nuclear localization sequences (NLS) to localize to the nuclear membrane surface and interact with importin-α/β, which in turn affected the transit of nuclear plasma material. Importazole, a small molecule inhibitor of importin, along with therapy that targets the Nup210 protein is anticipated to be a novel strategy for CRC treatment. Their combination may be able to more effectively lower CRC tumor load. In conclusion, Nup210 modulates cellular nucleoplasmic transport capability and cell surface NPC density via NLS, thus promoting CRC progression. This discovery validates the molecular function of NPC in the development of CRC and provides a theoretical foundation for NPC-regulated nuclear import targeting as a therapeutic strategy for CRC.

Neuroprotective effect against amyloidogenic transthyretin aggregates - Induced cytotoxicity on human neuroblastoma cell by phenolic-rich Centella asiatica extract

Transthyretin (ATTR) amyloidosis is a progressive and life-threatening neurodegenerative disease caused by aggregation of the plasma transport protein, transthyretin, for which treatment is rare and cure unavailable. Centella asiatica is a small edible herb with a long history of neurological application in ethnomedicine. This work investigated whether hydrophilic extract of C. asiatica (CAB) could suppress the toxic effects of transthyretin amyloid aggregate (TTRa) in cell model derived from the same in vivo target. TTRa was prepared via thermal-induced aggregation. Chemical cross-linking and Tricine-SDS-PAGE, Thioflavin-T fluorescence, and TEM analyses confirmed that TTRa matched the profile of TTRL55P nonfibrillar amyloid aggregates. PrestoBlue cell viability assay revealed that exposure of IMR-32 human neuroblastoma cells to TTRa (2–8 μM) resulted in significant cytotoxicity. Conversely, exposure of IMR-32 cells to CAB did not adversely affect their viability. In addition, when IMR-32 cells were co-treated with TTRa and varied concentrations of CAB, the toxic effect of TTRa was significantly (p < 0.01) inhibited dose-dependently. The extract was found to possess potent radical scavenging effects, and quantitative RP-HPLC analysis showed that asiaticoside and phenolics were its main components. The cytoprotective effect against TTRa, antioxidant property, and good safety profile collectively suggest that CAB could be applied in the development of nutraceuticals or therapeutics against transthyretin amyloidosis.

Solar Flare Effects in the Martian Ionosphere and Magnetosphere: 3‐D Time‐Dependent MHD‐MGITM Simulation and Comparison With MAVEN and MGS

AbstractA comprehensive modeling study has been conducted to investigate space weather effects at Mars during the 10 September 2017 solar flare, utilizing an integrated framework that combines the global magnetohydrodynamic (MHD) model and Mars Global Ionosphere‐Thermosphere Model (MGITM). This is the first time the thermosphere‐ionosphere‐magnetosphere system is self‐consistently simulated under realistic, time‐varying conditions. Our simulations align well with observations from the Mars Atmosphere and Volatile EvolutioN (MAVEN). Recognizing that complexities due to highly disturbed upstream conditions and rotating crustal fields obscure solar flare effects in orbit‐to‐orbit comparisons, we perform controlled simulations of nonflare and flare cases and exploit their contrast to quantify spatiotemporal variations in flare impact. Our results highlight pronounced and rapid dayside ionospheric perturbations, contrasting with weaker and delayed nightside responses. Notably, in the topside ionosphere, and C densities increase primarily on the dayside below 300 km altitude, peaking with an increase of 20%–30%. The density shows a more significant increase of up to 50%, extending into the magnetosphere and nightside via plasma transport, increasing its total loss rate by 14%. We observe distinct altitude‐dependent patterns in dayside electron density enhancements in percent, characterized by a weakening with altitude and a rapid decay below 150 km in line with the flare development, and a gradual intensification between 150–300 km due to plasma transport and flare‐induced atmospheric upwelling. Earlier Mars Global Surveyor observations were limited to the low‐altitude pattern due to atmospheric expansion and missed the higher altitude variations observed by MAVEN.

Saturation of fishbone instability through zonal flows driven by energetic particle transport in tokamak plasmas

Saturation of fishbone instability through zonal flows driven by energetic particle transport in tokamak plasmas

Non-linear MHD modelling of transients in tokamaks: a review of recent advances with the JOREK code

Abstract Transient MHD events like edge localized modes (ELMs) or disruptions are a concern for magnetic confinement fusion power plants. Research with the MHD code JOREK towards understanding control of such instabilities is reviewed here. Experimental validation for unmitigated vertical displacement events (VDEs) progressed. The mechanism of vertical force mitigation by impurity injection was identified. Two-way eddy current coupling to CARIDDI was completed. Shattered pellet injection (SPI) was simulated in JET, KSTAR and ASDEX Upgrade (AUG) and ITER. Benign runaway electron (RE) beam termination in JET and ITER was studied. Coupling of kinetic REs to the MHD is ongoing and a virtual RE synchrotron radiation diagnostic was developed. Regarding pedestal physics, regimes devoid of large ELMs in AUG were simulated and predictive JT60-SA simulations are ongoing. For ELM suppression by resonant magnetic perturbations (RMPs), AUG, ITER and EAST simulations were performed. A free boundary RMP model was validated against experiments. Evidence for penetrated magnetic islands at the pedestal top based on AUG experiments and simulations was found. Simulations of the naturally ELM-free quiescent H-mode (QH) in AUG and HL-3 show external kink mode formation prevents pedestal build-up towards an ELM within windows of the edge safety factor. With kinetic neutral particles, high field side high density (HFSHD) formation in ITER was simulated and with kinetic impurities, tungsten transport in AUG RMP plasmas was studied. To capture turbulent transport, electro-static full-f PiC models for ion temperature gradient (ITG) and trapped electron modes (TEM) were established and benchmarked. Application to RMP plasmas shows enhanced turbulence in comparison to unperturbed states. Energetic particle (EP) interactions with MHD were studied. Flux-pumping that prevents the safety factor on axis from dropping below unity was simulated. First non-linear stellarator applications include current relaxation in l=2 stellarators, while verification for advanced stellarators progresses.

TECXY simulations of the power exhaust in the multi-impurity plasma of DTT reactor

Reduction of the heat load to plasma-facing components is a crucial problem for future fusion reactors like Divertor Test Tokamak (DTT). Mitigation of the power load via increased plasma radiation with the use of puffed ions of impurities would be one way to mitigate power in the scrape-off layer. This paper presents a numerical investigation of the impact of seeded impurities on the radiation pattern and the power load to the divertor plates of the high-field DTT reactor in the single null (SN) configuration. The simulations have been done with the use of the TECXY code, which solves multi-species plasma transport equations for multiple impurity species simultaneously and all associated ionization stages in a two-dimensional poloidal geometry. TECXY represents the model of plasma transport in the scrape-off layer region by a classical set of transport equations of multi-species plasma derived by Braginskii. The paper aims to compare the mitigation capabilities of neon and argon impurities seeded in the plasma of the DTT device and to obtain a significant energy flux reduction to the target plate at the smallest possible impurity concentration. Performed investigations showed the effects of neon and argon impurities seeding separately for constant electron density at the separatrix. It has been found that the decrease in electron temperature on the divertor plates up to 3 eV at the outer and the inner divertor plates and the peak power load below 15 MW m−2 at the outer divertor plate can be achieved with argon seeding and much lower impurity concentration than that in the case of neon impurity seeding. Studies have shown the complexity of the effect of neon and argon impurities on the boundary plasma. It was found that the reduction of temperature and the power on both divertor plates was the most effective for the high upstream plasma densities. The results show also that diffusive perpendicular transport strongly affects impurity radiation and thus plasma condition at divertor plates.

Model for plasma transport due to drift waves based on mappings including finite Larmor radius

Abstract Turbulence in plasmas is modeled by fluctuating electric fields that determine particle motion through the E × B drift velocity which can lead to chaotic behavior. When applied to an ensemble of plasma particles in the chaotic regime their transport is studied: the anomalous plasma transport. The fluctuations are modeled by a spectrum of traveling waves with a wide frequency span which converts the equations of motion into an iterative mapping. The statistical properties of transport are derived. When the waves amplitude is small the particle orbits are regular, but as it is increased the behavior becomes increasingly chaotic. The effect of finite Larmor radius and the presence of a background plasma flow is also studied. We show that when a thermal population of particles is considered, the transport becomes non-local, as evidenced by a non-Gaussian particle distribution function (PDF). We have analyzed two different kinds of sheared flows: (1) a monotonic velocity shear and (2) a non-monotonic shear. The presence of transport barriers associated with the sheared velocity is also studied. We also present the application of the same techniques to study the transport of energetic particles that are born with a monoenergetic distribution.

Neoclassical transport computations in non-isothermal tokamak plasmas

Neoclassical transport in a non-isothermal plasma in which each plasma species has different equilibrium temperature is investigated by solving the drift kinetic equation with a Fokker–Planck (FP) collision operator in a circular tokamak model. Since it is known that a linearized FP operator does not have a self-adjoint property in a non-isothermal plasma, approximate models are developed for comparison to intend to have the self-adjoint property in the non-isothermal case. To achieve this, we set a common temperature that the system should reach after a long time, and the individual temperature of each particle species is expressed by a parameter to measure a shift of the individual temperature from the common one. Then, both the Vlasov part and the collision term of the kinetic equation are expanded around the common temperature, taking the temperature shift parameter up to the first order. It is found that the lowest order collision term of expansion preserves the self-adjointness while the first-order, nonlinear FP term does not. A large difference of the ion heat neoclassical transport is found in comparison between the developed models with and without the self-adjointness and the original FP collision term in the non-isothermal plasma, especially in a strong temperature equilibration regime, showing that a contribution of the collision term without the self-adjointness seems to be significant. Furthermore, when an impurity species is included, the result is complicated where the usual enhancement in the main ion particle transport coefficient, due to the impurity effect, is rather suppressed with the increase in the ion heat transport coefficients by the non-isothermal effects.

ThunderBoltz: an open-source direct simulation Monte Carlo Boltzmann solver for plasma transport, chemical kinetics, and 0D modeling

Abstract Plasma-neutral interactions, including reactive kinetics, are often either studied in 0D using ODE-based descriptions, or in multi-dimensional fluid or particle-based plasma codes. The latter case involves a complex assembly of procedures that are not always necessary to test effects of underlying physical models and mechanisms for particle-based descriptions. Here we present ThunderBoltz, a lightweight, publicly available 0D direct simulation Monte Carlo code designed to accommodate a generalized combination of species and arbitrary cross sections without the overhead of expensive field solves. It can produce electron, ion, and neutral velocity distributions in applied AC/DC E-field and/or static B-field scenarios. The code is built in the C++ standard library and includes a convenient Python interface that allows for input file generation (including compatibility with cross section data from the LXCat database), electron transport and reaction rate constant post-processing, input parameter constraint satisfaction, calculation scheduling, and diagnostic plotting. These codes can be accessed at the repository: https://github.com/lanl/ThunderBoltz. In this work we compare ThunderBoltz transport calculations against Bolsig+ calculations, benchmark test problems, and swarm experiment data, finding good agreement with all three in the appropriate field regimes. In addition, we present example use cases where the electron, ion, and background neutral particle species are self-consistently evolved to model the background kinetics, a feature that is absent in fixed-background Monte Carlo and n-term Boltzmann solvers. The latter functionality allows for the possibility of particle-based chemical kinetics simulations of the plasma and neutral species as a new alternative to ODE-based approaches.

Three-Dimensional Direct-Implicit Particle-in-Cell Model Using Trilinear Anisotropic Immersed-Finite-Element for Plasma Propulsion

Efficiently and accurately calculating the plasma transport process is one of the difficulties in aerospace plasma application simulation, especially in the magnetic sail spacecraft applications that have a huge size. This paper develops a three-dimensional trilinear anisotropic immersed-finite-element direct-implicit particle-in-cell (IFE-DIPIC) model to solve the problem of large-scale, long-term evolution plasma with complex interfaces. The model uses the DIPIC method to track the motion of particles in the plasma while simulating the anisotropic electric field containing an interface by using a modified trilinear anisotropic IFE method. Compared to the previous models, the developed model in this paper allows for the use of larger spatial and time steps in the Cartesian meshes without inducing numerical divergence. Using an interface-independent mesh avoids redundant interpolation in the PIC method, further improving efficiency. These advantages significantly improve the efficiency in solving actual complex three-dimensional plasma physics problems. The accuracy, efficiency, stability, and applicability of the proposed model are proved through numerical examples and the application in magnetic sail. The simulation results indicate that the developed model can efficiently simulate the actual working conditions of magnetic sails. The performance is significantly influenced by both the direction and magnitude of the magnetic moment.

Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions

Abstract Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues in burning plasma are: alpha-channeling (ion heating by alpha particles), turbulence and transport in electron dominant heating helium ash exhaust, reduction of the divertor heat load. To solve these problems, understanding the basic plasma physics of (1) wave–particle interaction through (inverse) Landau damping, (2) characteristics of electron-scale (high-k) turbulence, (3) ion mixing and the isotope effect, and (4) turbulence spreading and detachment, is necessary. This overview discusses the experimental studies on these issues and turbulent transport in multi-ion plasma and other issues in the appendix.

Occurrence of Kelvin–Helmholtz Instability at Lunar Distance Magnetopause: ARTEMIS Observation

Kelvin–Helmholtz waves can be observed frequently at the near-Earth magnetopause and play an important role in the transport of particles, momentum, and energy from the solar wind to the magnetosphere. This work analyzes the occurrence of Kelvin–Helmholtz instability (KHI) at lunar distance magnetopause, which has not been thoroughly studied currently based on Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun satellite observations, and it also investigates the effect of the upstream solar wind and interplanetary magnetic field (IMF). Statistical results show that (1) the occurrence rate is about 15% of the time at lunar distance, lower than at the flank magnetopause, and (2) the occurrence rate decreases with the magnetoacoustic Mach number, Alfvén Mach number, solar wind velocity, and dynamic pressure but only shows a slightly positive correlation with solar wind density. Unlike at the dayside magnetopause, the occurrence rate of KHI diminishes as the solar wind velocity increases at the lunar distance magnetopause, and (3) the occurrence rate decreases with IMF amplitude and is influenced by IMF orientation. As a function of the IMF clock angle, the occurrence rate reaches its maximum at ∼24% when the clock angle is zero. The statistical results are basically consistent with the currently accepted linear theory of KHI, except for a lower rate for higher-speed solar wind. This work contributes to understanding the excitation and evolution of KHI along the magnetopause and plasma transport process in the tail magnetopause.