A dual-collector ExB probe has been developed to enable simultaneous measurements of ion velocity in electric propulsion (EP) testing. In this configuration, a single filter section feeds into two drift tubes of differing lengths, each terminating in an individual collector. This enables the probe to simultaneously measure the ion velocity distribution function (IVDF) in two resolution regimes. The dual-collector ExB probe was tested on a 10cm gridded ion thruster operating on air, which generates a plume containing O2+, N2+, O+, and N+. The long drift tube configuration resolved all four distinct ion population peaks in the IV curve, whereas the short drift tube configuration merged the four species peaks into two (one for molecular species, the other for atomic species). The IVDFs were estimated from the long ExB probe measurement, the short ExB probe measurement, and both the long and short ExB probe measurements together. The most probable energy, distribution full-width half-maximum (FWHM), and ion species fraction were calculated from these estimated IVDFs. The uncertainty in the most probable energy was mainly contributed by the Wien velocity uncertainty (about 10%), which is consistent regardless of the different ExB probe measurements. When both long and short measurements were used together, the average uncertainty in the FWHM was reduced to 0.040 km/s from 0.063 and 0.211 km/s for individual long and short ExB probe measurements, respectively. By using together the long and short ExB probe measurements, the uncertainty in ion species fraction was reduced to ∼10%, compared to ∼20% and 30% for the individual long and short ExB probe measurements, respectively. This study demonstrates the ExB probe's capability for concurrent IVDF measurements in EP environments, confirms the reduction in the uncertainty in the estimated IVDF and the calculated ion species fraction, and highlights the limitations of purely analytical transmittancy estimates when nonuniform fringe fields induce beam distortion.

Analysis of electron power absorption and loss mechanisms in the discharge chamber of air-breathing radio-frequency ion thruster

Numerical simulation study on ionization and acceleration characteristics of low power iodine radio-frequency ion thruster

Impulse scaling during magnetic reconnection, the magnetic energy conversion to kinetic energy, via direct Mach probe measurements in Magnetic Reconnection Experiment is examined. Ion exhaust velocity and impulse scalings with reconnecting magnetic field during the push phase of driven reconnection are presented. The outflows and impulse measurements are compared with global MHD simulations. Both measurements and simulations reveal a favorable scaling, greater than linear, of impulse with reconnecting field. These scaling results establish that magnetic reconnection could be utilized for plasma propulsion.

Abstract Air breathing electric propulsion technology is one kind of resource in-situ utilizing spacecraft power technology, which can reduce launching cost, increase the spacecraft’s lifetime and has broad application prospect. Environmental gas electric thruster has low efficiency compared with traditional Xe thruster. The electric thruster’s efficiency is seen as the most important factor determining whether the air breathing electric propulsion technology is feasible. In this paper, A 10 cm Kaufman electric thruster was used for experimental study with environmental gas working matter, and the hollow cathode used Xe propellant. In this paper, the relationships between the thruster’s efficiency and the mass flow rate, screen grid voltage and anode voltage were studied. The rule of the hollow cathode anode voltage changing with time in the environmental gas was also studied. The obtained results indicate that Kaufman electric thruster has relative high efficiency with environmental gas and suitable for air breathing electric propulsion technology, the changing rules of the electric thruster’s efficiency can be used as the reference for the thruster optimization. In the 200 hours time scale, the performance of the hollow cathode was stable and can be used for in-orbit demonstration.

Low-frequency microwave absorption via size modulation and electromagnetic synergistic engineering in flaky GeP5

Data-physics Coupled Model for Ion Propulsion System

One of the strongest electromagnetic engineering approaches for enhancing antenna performance is the use of photonic crystal (PhC) substrates. This technique can be efficiently applied to antenna design and offers notable advantages, such as gain improvement, increased bandwidth, and frequency-dependent beam scanning. In this paper, a bow-tie dipole antenna has been developed for terahertz operation over the 0.39–1.3 THz band, presenting a novel structure capable of producing strong ultra-wideband (UWB) field enhancement within its feed gap. The feed gap between the two metallic arms has a slot width of 1.24 λ0 (λ0 is the wavelength in free space at a center range of 0.8 THz), which facilitates the generation of an enhanced electric field. The PhC substrate enables surface-wave control through dispersion engineering, thereby enhancing the radiation efficiency of the antenna. The proposed antenna exhibits a radiation efficiency of approximately 73–93% over the entire UWB frequency band. Furthermore, the PhC substrate antenna achieves a maximum gain of 21 dB, exceeding that of a homogeneous-substrate THz bow-tie antenna by at least 3.3 dB. The results indicate that the antenna achieves |S11| < −10 dB impedance matching over the bandwidth of 105.9%, ranging from 0.4 to 1.3 THz. The proposed bow-tie dipole antenna integrated with a PhC substrate demonstrates a wide beam-scanning capability from −54° to +74° across the 0.39–1.16 THz band, while maintaining a compact footprint of 14.9 λ0 × 22.4 λ0. This combination of wide scanning, broad bandwidth, and ultra-low profile represents a notable advancement in the development of compact THz radiating structures.

In complex terrain modern day geophysical electromagnetic work or microwave engineering needs a good model of the electro magnetic field to succeed. The outdated numerical calculations relying equally distributed reguar grid finite diff, and un-even grounds like waves, faults, all sorts of messed up 3D anomalous distortions, it would greatly warp the local EM field response data points in ALL but maybe some last steps before 'inverted', and trying to interpret that result. In order to solve the bottleneck problem, we explore and realize a 3D vector finite element forward modeling method of electromagnetism field with unstructured tetrahedron grids. Utilizes very closely conformed unstructured grids to closely approximate complicated geological model and also has vector basic function based on edge element to remove these kinds of pseudo solution that you have when you do normal node FEM method. This article describes how to obtain the weak form integral equation of Maxwell’s equation of the electric field curl and introduces a pre-process Krylov subspace iteration solution strategy for solving big sparse complex linear equations. It is also the proof for truth of both its accuracy and strength in converging, it has experienced a lot of easy numerical check upon simple halfspace, roughest terrain and even most complicated bodies with deeply buried 3D high conductivity targets. The article can be considered true 3dfoward Model Theory Support and algorithm Basis To Get True Data Refinements And Exact Location Of Any Complex Geologic Body Within China while carrying out an Electromagnetic Investigation.

We investigate facility effects on a reduced-scale gridded-ion-thruster plume using a fully kinetic, three-dimensional particle-in-cell/Monte Carlo collision solver coupled with a direct simulation Monte Carlo neutral background. This approach enables detailed examination of key plasma processes governing beam neutralization and wall interactions under ground-test conditions. We find that inelastic electron cooling is essential for achieving a physically consistent, neutralized beam. Increasing the background pressure enhances ion–neutral collisions, leading to more charge- and momentum-exchange events that reduce ion mean energies, broaden the beam, and increase sidewall losses. Inelastic processes flattens the potential, sustains quasi-neutrality, and preserves beam collimation farther downstream. Single-particle trajectory analyses show that primary electrons undergo mixed escape and temporary trapping, while low-energy post-inelastic electrons remain confined, sustaining the neutralization cloud. Sheath diagnostics reveal that at the beam dump, classical Child–Langmuir and Hutchinson models underpredict the sheath length due to residual electrons, while near the sidewall, the sheath is truncated by beam-sheath interference within the compact domain. Current-flow analysis indicates that higher background pressure conditions yield lower beam energies and increased sidewall currents.

This study presents a global model analysis of a water-fueled gridded ion thruster powered by a radio-frequency inductive coil. A comprehensive reaction set is developed to capture the complex plasma chemistry of water, including the formation and ionization of secondary neutrals generated through dissociation and neutral–wall recombination reactions. The global model solves coupled particle and energy balance equations to predict plasma properties and thruster performance as a function of operating parameters, such as the input radio frequency power and the propellant mass flow rate. The results demonstrate that while water exhibits a greater discharge complexity than xenon, the dissociative pathways contribute only marginally to the formation of light ions, such as H+ and H2+. The discharge is instead dominated by heavier ions, such as H2O+, O+, and OH+, which contribute to meaningful thrust production. Compared with xenon (for a 12-cm diameter thruster studied here), water exhibits higher electron temperatures and an enhanced coil–plasma power transfer efficiency, although the propellant mass utilization efficiency and the thrust-to-power ratio are lower. A thrust performance analysis reveals that water can achieve a competitive thrust and specific impulse at higher input powers, establishing its viability as an alternative propellant. Overall, the model provides a robust foundation for the development of future water-fueled electric propulsion systems and addresses a critical gap in general low-temperature water plasma research.

In this study, a prototype of the gas discharge chamber for a high-frequency ion thrust engine was fabricated and tested using a composite material based on a ceramic powder filler and an organosilicon binder. By measuring the physical parameters of the high-frequency ion thrust engine at conditions close to real operational conditions, it was established that the most resource-limiting factor for the operation of polymer-composite discharge chambers is matrix aging under the influence of ultraviolet (UV) radiation emitted by the thruster’s plasma. It is shown that the primary approach to creating a polymer-composite material involves forming a thin, plasma-facing layer of UV-resistant, shaped ceramic elements assembled into a locking mechanism, which are integrated into the discharge chamber mass via adhesive interaction with a temperature-resistant polymer. The novel approach to solving the problem of manufacturability of such composites is achieved through the use of two independent additive processes. The first, a close analogue of fused deposition modeling, allows for the formation of shaped ceramic components. The second, material jet (material inkjet printing), ensures the final assembly of the discharge chamber by forming a polymer matrix.

Magnetostrictive materials hold non-contact stimulation-responsive properties, which exhibit promising prospects in aviation and marine engineering. However, high-end equipment is frequently employed in changeable environments during service. A slight deformation in magnetostrictive effect makes it complicated to meet the demands of macroscopic applications. 4D printing is that the 3D printed object could evolve with time when it is under specific stimuli. Herein, we present a method of 4D printing magnetostrictive materials to endow service parts with laser-responsive macroscopic strain and magnetically responsive microscopic strain. The internal stress in laser powder bed fused magnetostrictive samples can be redistributed via adjusting laser stimulation parameters and scanning strategies. This redistribution induces macroscopic plastic deformation at the selected location. Dynamic control of the samples' microstructure and electromagnetic properties can be accomplished during shape-morphing stimulation. This breakthrough addresses the strain scale limitations of magnetostrictive materials, promoting the cross-scale shape-morphing application of 4D printing in electromagnetic engineering.

Abstract During the discharge process of Hall thrusters, various plasma instabilities occur across frequency bands. The ion transit-time instability (ITTI), with frequencies of 100-500 kHz and periods matching ion transit times through the acceleration region, significantly impacts ion energy distribution and thruster performance. While influenced by channel structure and discharge conditions, its mechanisms need clarification. This study develops a one-dimensional axial hybrid model, treating ions and neutrals kinetically via particle-in-cell methods and electrons as a fluid, to investigate ITTI generation and effects of channel length, gas mass flow rate, and magnetic field strength. Results show the ITTI originates from ion acoustic waves driven by electron pressure gradients, inducing density perturbations and electric field oscillations that propagate downstream at ion-like phase velocities. This causes periodic variations in discharge current, ion velocity, and density, generating ions into low- and high-energy groups, with low-energy ion packet dominating ITTI propagation. Stronger magnetic fields intensify the electric field and amplify ITTI oscillations. Longer channels modify magnetic field distribution, increasing electron mobility and reducing ITTI amplitude and frequency. Higher mass flow rates increase ion flux, amplify electric field oscillations and raise the ITTI amplitude and frequency. Findings validate the dispersion relation theory, with growth rate inversely proportional to the square root of electron mobility and frequency correlated with ionization rate and atom density.

Abstract The Ionic Liquid Electrospray Thruster (ILET) is highly promising for micro/nanosatellite propulsion and receives widespread attention. In order to further improve the performance of ILETs, based on the particle-in-cell (PIC) method, this study numerically investigates the effects of plume ion composition on plume characteristics, including ion distribution and electric field distribution, as well as propulsive performance of ILETs, operating in both uni-thruster and bi-thruster modes. A more realistic mixed ion model is utilized, incorporating dimer and trimer ions in the plume in addition to the commonly considered monomer ions. The results show that the presence of dimer ions significantly alters the ion distribution of plume and affects the thrust and specific impulse of ILET in both modes. In the uni-thruster mode, the plume evolves from a uniform semicircular shape to a more complex structure, with polymer ions aggregated in the central region and monomer ions dispersed in the external region, as the proportion of dimer ions increases. Due to the phenomenon of ion reflux, thrust and specific impulse also increase with the dimer ion ratio. In the bi-thruster mode, the ion distribution of plume becomes more concentrated in the external region with the addition of dimer ions, and the optimal performance is achieved with a dimer ion content of 30%. These findings provide valuable insights into the behavior of ion thrusters and offer guidance for optimizing the performance of ILET in practical space applications.

Experimental study on performance improvement of a water-fueled miniature ion thruster by electrode voltage

During ion thruster operation, electromagnetic waves propagating through the plasma plume undergo absorption and refraction effects. This paper presents a graphics processing unit (GPU) parallel ray tracing (RT) algorithm for inhomogeneous media to analyze plasma plume-induced perturbations on the radiation characteristics of a satellite reflector antenna, substantially improving computational efficiency. This algorithm performs ray path tracing in the plume, with the vertex and central rays in each ray tube assigned to dedicated GPU threads. This enables the parallel computation of electromagnetic wave attenuation, phase, and polarization. By further applying aperture integration and the superposition principle, the influence of the plume on the far-field antenna radiation patterns is efficiently analyzed. Comparison with serial results validates the accuracy of the algorithm for plume calculation, achieving approximately 319 times speed-up for 586,928 ray tubes. Within the 2–5 GHz frequency range, the plume causes amplitude attenuation of less than 3 dB. This study provides an efficient solution for real-time analysis of plume-induced interference in satellite communications.

Purpose This study presents a unified and comparative analysis of uniform diffraction fields generated by circular apertures on three canonical surface types: opaque, perfectly electric conductive (PEC) and perfectly magnetic conductive (PMC). This study aims to explore how these boundaries influence field uniformity and angular behavior under identical conditions. Design/methodology/approach The classical boundary diffraction wave (BDW) theory is applied to the opaque case, and an extended BDW formulation is developed for PEC and PMC surfaces to account for reflective effects. Analytical expressions are derived, and numerical simulations are conducted to examine the impact of aperture size and observation distance. Findings The results reveal that PEC and PMC surfaces introduce significant modifications to the angular distribution of the diffracted field, including phase reversals and amplitude oscillations. The extended BDW model successfully predicts these behaviors, particularly near shadow boundaries and axial zones. Research limitations/implications The study is limited to idealized geometries and monochromatic wave excitation. It does not yet consider material losses or complex aperture shapes. Future work may expand this framework to more realistic electromagnetic structures. Practical implications The findings can help electromagnetic engineers optimize antenna design, stealth surfaces and metastructures by offering better control over field uniformity and diffraction behavior across different surface types. Social implications While the work is theoretical, it supports technological development in sectors like communication, defense and sensing, contributing indirectly to infrastructure reliability and performance. Originality/value To the best of the authors’ knowledge, this is the first unified parametric study that simultaneously evaluates opaque, PEC and PMC surfaces using classical and extended BDW approaches. It introduces a novel high-frequency framework for comparing uniform diffraction field behavior across distinct boundary conditions.

A torsional thrust stand with heavy load and stability has been developed for electric propulsion thruster testing under vacuum conditions. The thrust measurement principle is based on torsional pendulum mechanics combined with capacitive displacement sensing. The stand features a closed loop and non-contact capacitive detection to achieve a resolution of 0.1 mN within a measurement range up to 100 mN, with experimental validation conducted at the 5 mN level. Calibration was performed using two separate approaches: one based on electromagnetic force detection and another based on gravitational mass measurements, and experimental validation was conducted using an ion thruster under a vacuum of 10−4 Pa. The results demonstrate that the stand achieves stable and accurate thrust measurement, providing an effective tool for performance evaluation of submillinewton- and low-thrust electric propulsion systems.

Electric propulsion is a method of spacecraft propulsion, where thrust is generated by accelerating ionized gas using electric fields. It is an essential part of deep space mobility, being far more fuel and space efficient than combustion thrusters. Gridded ion thrusters are a common mean of achieving electric propulsion, utilizing multiple grids with a voltage difference to accelerate ions. Because electric propulsion mainly employs electrostatic forces, which are easily controlled, it is easier to simulate than chemical propulsion, which requires the determination of reaction rates, collisions and internal pressure forces. Thus, a large amount of electric propulsion research is conducted through simulations, iterating tests in order to optimize thruster designs. However, highly accurate simulations require large computational resources to mitigate numerical noise. Naturally, it would be useful to find any way to minimize computation times while still producing accurate data. To explore this concept, we created a particle-in-cell simulation which deliberately underresolves particle statistics to determine the effects on extensive and intensive metrics. We hypothesized that intrinsic values would still be accurate while extrinsic values would diverge greatly. We normalized the results by a reference value and quantitatively compared them to the experimental data, which showed that intensive properties like specific impulse and velocity retained high accuracy with low particle number. Our findings suggest that preliminary simulations could be run quickly with much lower particle counts before more technically demanding and comprehensive simulations are performed.