Electromagnetic launch technology accelerates projectiles through electromagnetic forces. The projectiles’ performance significantly influenced by the flight stability of the projectiles. This paper focuses on a rotational armature electromagnetic launch system, employing an asymmetric additional rail structure to analyze its electromagnetic field characteristics and armature rotation mechanisms via numerical simulation. A three-dimensional transient model was established using LS-DYNA to investigate the kinematic Characteristics of the armature, current density distribution, magnetic field evolution, and Lorentz force distribution under the influence of additional rails. The simulation results demonstrate that the additional rails significantly enhance the inductance gradient, enabling the armature to achieve a muzzle velocity of 600 m/s and a clockwise rotational speed of 205,274 r/min. The current density, affected by skin and proximity effects, concentrates on the inner edges of the rails and the outer edges of the armature, exhibiting an asymmetric bias. The magnetic field intensity increases with the armature’s velocity, forming a “trailing” diffusion structure at high speed. The Lorentz force predominantly concentrates at the contact edges between the armature and rails, with its asymmetric distribution identified as the key driver of armature rotation. This study reveals the regulatory mechanisms of additional rails on electromagnetic field distribution and armature motion characteristics, providing a theoretical foundation for optimizing the design of rotational armature electromagnetic launch systems.

The enhanced electromagnetic railgun is a novel launching system whose structural dynamic characteristics directly influence device lifespan and precision. This paper investigates its modal characteristics and the influence of structural parameters. Dynamic differential equations were used to establish relationships between modal properties and structural stiffness, mass, and damping. Experimental measurements using multi-point triaxial acceleration sensors captured the first six natural frequencies and mode shapes. A finite element model (FEM) was established and validated. Based on the validated model, the effects of the number of fastening devices, winding layer thickness, and rail material on modal properties were analyzed.

Electromagnetic projectile launch uses electromagnetic force. After the armature exits the barrel, the leftover energy in the launch system is released via the muzzle plasma arc. This high-energy arcing can harm the launch system. To grasp the muzzle plasma arc’s development and its impact on the muzzle environment, this paper employs fluid simulation software. For a 16 mm-caliber launch system, combining magnetohydrodynamics with user - defined functions (UDF), a 2D fluid - structure interaction model is built, achieving multiphysics coupling of electromagnetic, flow, and thermal fields. The simulated potential difference between the guide rails matches experimental data, showing the simulation’s reliability. Results indicate that the muzzle plasma arc gradually transfers from the plasma arc circuit to the guide rail circuit, and it has a relatively stable phase. Its high temperature and shock waves expand inward and outward. The outward shock wave alters the initial muzzle flow field, while the inward expansion causes reverse airflow and blowback. After briefly reversing, the internal airflow moves outward again. This aligns with experiments where molten metal is ejected as the plasma arc fades. These findings offer theoretical support for muzzle material/structure selection, dynamic launch experiments, protection design, and electromagnetic launch interior ballistics research.

Based on the mechanism of flash Joule heating (FJH) for graphene synthesis, this study developed a novel flash Joule heating power supply device to enable the efficient production of graphene using lignin as the carbon source. The power supply features a wide adjustable output voltage range from 0 to 900 V and a current output capacity up to 1000 A, with controllable pulse durations ranging from 0 to 500 ms. When combined with a lignin-based load setup, experimental results demonstrate that direct current conduction through the carbon source significantly reduces the energy consumption during graphene conversion. Under a discharge voltage of 300 V, Raman spectroscopy of lignin mixed with carbon black shows the lowest defect level (ID/IG = 0.457) and exhibits characteristics of monolayer graphene (I2D/IG = 2.104). Properly increasing the number of discharges effectively reduces the number of graphene layers, whereas excessive discharges may lead to restacking of graphene sheets. This power supply demonstrates strong energy output capabilities and shows promising potential for the scalable production of graphene.

The geometric shape of the convex track has a significant impact on the sliding electrical contact characteristics in electromagnetic orbit launch devices. This article uses finite element software to establish a bidirectional coupling simulation model of structural field and electromagnetic field for a 20 mm diameter launch device, and studies the influence of convex track arc surface on pivot rail contact pressure and current distribution under different curvature radii. The simulation results show that as the curvature radius of the track arc increases, the contact pressure between the pivot and the track gradually shifts from the center to the edge, and the high current density area also moves from the center of the contact surface to the edge. In a 20 mm caliber launch device, when the curvature radius of the curved surface is 10 mm, the efficiency of the launch device is the highest and the current density distribution is the most uniform. By studying the variation of current density at the contact interface of the pivot rail with the curvature radius, a theoretical basis is provided for optimizing the geometric shape of the convex rail.

To meet the requirements of electromagnetic launch devices, this article proposes a cascaded high-voltage power supply topology based on integrated charging and discharging of lithium batteries for pulsed capacitor charging. Lithium batteries are used as long-term energy storage units to meet the mobility requirements of electromagnetic launch devices, and only one charger module is used to fully charge all battery power to realize the lightweight of electromagnetic launch devices. A multistage constant current charging (CC Charge) strategy is proposed based on this topology, which can fully charge all batteries at the same time. In addition, for the discharge of the battery to the pulsed capacitor, a double closed-loop PI control strategy with outer-loop output limiting is proposed to realize stable and CC Charge of the pulsed capacitor to 7000 V, which improves the operational stability of electromagnetic launch devices. A MATLAB/Simulink simulation model is built to verify the charging and discharging control strategy, and the results show the effectiveness of the proposed circuit topology and control strategy, which can reduce the complexity of electromagnetic launch devices and control the batteries to discharge stably at constant current.

In augmented linear drive motors with large current, the tail section requires a pair of bridging conductors to connect the main rail and the augmented rail. In previous experiments, to ensure uniform magnetic field conditions during armature acceleration, the armature’s starting position was typically placed ahead of the tail bridging conductors (along the direction of motion) to avoid magnetic field abruptions that could affect acceleration and motion stability. This paper investigates the relative positional relationship between the armature’s starting position and the tail bridging conductors. The electromagnetic driving force on the armature at different positions is calculated, and its influencing factors are analyzed. The feasibility and risks of placing the armature’s starting position inside the tail bridging conductors are explored. The findings can guide the determination of the armature’s starting position and the optimized design of tail bridging conductors in augmented large-current linear drive motors.

Deposition occurs on the rail surface during the start-up stage of the launching process. These phenomenon influence the velocity of the armature, the acceleration of the armature and the launching stability of the launcher. In this article, 15 experiments with the linear current density of 19 kA/mm were carried out. The morphology of the rail surface at the armature start-up stage and the start-up time of the armature were measured by a 3-D laser profilometer and a high-speed camera, respectively. Three conclusions are obtained: 1) the morphology of the deposition layer on the surface of rails is high at the edges of armature-rail interface and low in the middle of interface because of nonuniform contact pressure and temperature; 2) as the number of experiments increases, the thickness of the deposition layer on the rail surface increases and then tends to stabilize; and 3) the start-up time of the armature increases rapidly, and then tends to stabilize. Moreover, to analyze the reason for the distribution of deposition layer on the rail surface observed during start-up stage in experiments, the contact pressure, current density and Joule heating were calculated. Results show that the contact pressure of the edges of the armature is relatively high, and these areas are also where high temperature is concentrated on the surface of the armature.

With the development of electromagnetic launch (EML) technology, the demand for engineering and practicality of electromagnetic energy device has become increasingly urgent. The working mode of repetitive frequency launch increased higher technical requirements for the primary power supply, pulsed power supply, loading system, and close coordination and strict time sequence control among various systems. Based on the requirements of repetitive frequency operation, the control architecture based on the primary power supply cascade controller, pulsed power supply time sequence trigger, and loading system control machine is build, and a control network is constructed using optical fiber composite communication. By designing the logical relationship between control signals and feedback states among each controller, a control strategy following the repetitive launch process is established. The close cooperation and effective control of the various systems are achieved, and the repetitive frequency launch experimental task is completed. The experimental results demonstrate that under the communication method and control strategy, the design indicators of repetitive frequency launch were met and the control strategy is effective.

Against the high-power application backdrop of lithium-ion batteries (LIBs), issues like severe temperature rise from rapid high-current discharge (triggering safety concerns) and energy density loss due to excessive high-power enhancement lead to distinct material systems/manufacturing processes between high-power and conventional LIBs. This investigation analyzed aging and thermal runaway (TR) behaviors of high-power lithium iron phosphate (LFP) batteries under overcharge. At 1C discharge, mild initial overcharge minimally affected internal resistance/capacity but accelerated high-rate discharge capacity fading; increased overcharge intensified capacity degradation and voltage drop, with aging initially dominated by lithium-ion loss. Disassembling 1C constant-current overcharged batteries and analyzing voltage curves identified five reaction stages: overcharge lag, stable delithiation, electrolyte oxidative decomposition, LiFePO4/electrolyte depletion, and short-circuit. TR involved stage-specific voltage/temperature variations (high peaks) without ignition/explosion. These confirm high-power LFP batteries' overcharge tolerance, supporting prospects in integrated energy storage systems (IESS).

The application of a multiphase air-core pulsed alternator (APA) power supply system in railgun has been studied. First, the working principle of the multiphase APA power supply system driving the railgun is introduced in detail, and the mathematical models of the multiphase APA and the railgun are given. Second, the discharge characteristics of the multiphase APA power supply system are analyzed. The relationship between the load current and the phase current is expounded at the theoretical level, and the characteristics such as the amplitude and pulsewidth of the phase current during the discharge process of the eight-phase motor are analyzed and parsed. Then, a field-circuit coupling simulation model is constructed to simulate and analyze the discharge process of the multiphase APA driving the railgun, verifying the correctness of the theoretical analysis. Finally, the experimental platform of multiphase APA driving the railgun is built, and the launch experiments are successfully conducted. Meanwhile, valuable experimental data are also provided for the subsequent further experiments.

The temperature of the rail is increasing in a short period of time by the Joule heat generated by the high current passing the contact surface between the rail and the armature, the frictional heat generated by the armature’s movement on the rail surface during the electromagnetic launching process. The launch performance is affected by the surface temperature of the track sharply increases and a decrease in the mechanical performance of the rail. The rail temperature simulation model and tests of the model is established by launch experiments. The model is modified and improved to provide support for the optimization design of thermal management system.

With the continuous improvement of high power density, fast charging rate, and miniaturization requirements of pulse power supplies, a high-voltage constant current (HCC) charging power supply suitable for fast charging of pulse capacitors is developed. The low-voltage cascade topology structure is employed, which achieves high-voltage output. To achieve constant current control, a combined modulation strategy based on PWM carrier phase shifting and carrier stacking is utilized. This modulation method can reduce output current ripple, switch losses, and inductance, which are all factors improving the power density of HCC charging power supply. Firstly, the working principle of the power system is analyzed. Secondly, the simulation models are set up in MATLAB, and the simulation results verified the feasibility of the control strategy. Finally, the developed power supply was subjected to high-voltage experiments under 0.3F capacitor load, and the experimental results showed that the constant current output effect of the power supply was good and the operation was reliable.

An electromagnetic launcher is a kind of rail symmetrical distribution launcher. When a symmetrical current is passed between the rails, the strong magnetic field is symmetrically distributed between the two rails. The bore parameters affect the efficiency and accuracy of the launcher. Launching accuracy is an important evaluation content for assessing the technical index of the electromagnetic launcher. In this paper, experiments were carried out to investigate the influence factors of the launching accuracy of a small-caliber electromagnetic launcher. The experimental results show that: (1) The consistency of the muzzle velocity increases with the increase of the rail separation. When the rail separation is 16 mm, the mean deviation of the muzzle velocity is the smallest, at 16.71, 15.72, and 10.77, respectively. When the rail separation is constant, the mean deviation of the muzzle velocity is 10.77, while the convex arc height is 1 mm. Increasing the rail separation and the convex arc height is beneficial to improving the consistency of the initial velocity. (2) When the rail separation is certain, increasing the convex arc height significantly improves the firing accuracy and firing intensity, and when the convex arc height increases from 0 mm to 1 mm, the firing intensity is reduced from 9.6 to 4.41, and the firing intensity decreases from 10.34 to 5.79, which significantly reduces the firing deviation and increases the muzzle consistency of the armature under repeated firing conditions. (3) The muzzle attitude is mainly affected by the effective mass ratio. Within a certain range, adding load can make the muzzle attitude of the integrated projectile more stable. However, when the load mass is too large, it will have a negative impact on the muzzle attitude. The results show that under the two cases of the effective mass ratio of 0.43 and 0.49, the integrated projectile has a better muzzle attitude.

A megawatt-level high-voltage charging power supply suitable for fast and cyclic charging of pulse capacitors is developed to meet the requirements of electromagnetic launch devices. Batteries are used as energy storage units to meet outdoor application environments. The low-voltage cascade topology is used as the charging circuit, which achieves high voltage through the series connection of low-voltage repetitive battery modules. The control strategy of time-sequence encoding is adopted to control the activation time of each battery module. In addition, a method for eliminating reverse voltage of pulse capacitors is proposed, which can convert reverse energy into charging energy. The power supply consists of 16 battery modules, with the peak power of 5.5 MW, the output voltage of 0-7 kV, the average charging current of 800 A, the charging rate of 2 MJ/s, the charging efficiency is 95.5%, and the ability to cyclic charging for more than ten times. The power supply is verified through simulation and experiments, and the results prove that the output capability meets the design specifications, and the reverse voltage can be eliminated, which also helps improve the charging rate.

To meet the requirements of the electromagnetic rail launch system for a large-scale pulsed power supply to output stable discharge current, seeking a fast solution method for the discharge sequence and obtaining a reasonable triggering sequence is a key direction of research on large-scale pulsed power supply. This article proposes a sequence solution strategy based on charge equivalent. Based on the principle of equal charge amounts during the discharge process, the relationship between the current waveforms and the number of modules at different stages is obtained. Then, the triggering sequence of each module is solved according to the set current requirements. A typical representative system was established to verify the feasibility and accuracy of the above solution strategy. The results show that the triggering sequence obtained by the solution strategy can make the discharge current meet the requirements and improve the solution efficiency. The sequence solution strategy based on charge equivalent can not only avoid complex mathematical calculations to obtain the triggering sequence, but also effectively improve the discharge success rate of the engineering test.

The armature-rail interface of the electromagnetic launchers conducts the current with megamperes in the milliseconds. This extreme condition results in the rapid melting of the metal at the armature-rail interface, followed by the outward ejection of molten metal. The molten metal with high-velocity and high-temperature impacts rails and insulators, causing serious grooving damage and metal pollution, which limits the performance and service life of the launcher. To study this phenomenon, a 3-D electro-magnetic-thermal-mechanical-fluid multiphysics coupling model was established, taking into account dynamic contact resistance, velocity skin effect, development trend of the liquefied layer, and fluid pressure. The calculation results show that the liquefied layer initially appears at edges of the front of the armature. And rapidly expands toward the center of the tail. The maximum liquid pressure occurs neartheinterface between solid and liquid. Due to the degradation of the armature material properties caused by high temperatures, high fluid pressure facilitates the peeling of solid part of the armature, thereby accelerating the expansion of the eroded region. At 2.5 ms, the armature melts a volume of 11.91mm(3), with a maximum melting depth of 0.565 mm occurring in the edge region of the armature. Meanwhile, the maximum velocity of the liquefied layer reaches 450 m/s.

The contamination degree, which is used to evaluate the degradation of insulation performance in solid-armature rail launchers, is proposed based on the study of pollution flashover in power systems. Two methods for describing the contamination degree, namely the leakage current method and the partial surface conductivity method, are introduced based on the contamination characteristics of bore insulators. The correlation between two descriptive parameters, the leakage current I-leak and the partial surface conductivity sigma(p) , and flashover voltage U-f was investigated under various sample sizes and experimental conditions. Results indicate that the partial surface conductivity method, in general, is more suitable for describing the contamination degree of bore insulators. In cases where faults or severe contamination occur on insulators, the flashover voltage U-sigma predicted by sigma(p) is closer to the measured value U-f than the U-I predicted by I-leak , with U-I typically being higher than U-f . For a large sample size of 288 samples, the correlation coefficient between sigma(p) and U-f was found to be -0.89. The relationship between sigma(p) and U-f follows a power function, and the regression fitting yielded the equation y=0.853 x(-0.1) . The establishment of the contamination degree and the application of descriptive methods provide valuable insights into the damage distribution and degradation mechanisms of bore insulators.

This article proposes a method for calculating the distribution of the deposition layer on the rail surface based on the simulation of armature melting. A series of 49 launch experiments were conducted to study the distribution of the deposition. The thickness of the deposition, as obtained from both simulations and experimental measurements, shows strong agreement, confirming the accuracy and reliability of the proposed calculation method. Both the simulation and experimental findings reveal that the deposition is thicker during the initial stages of the launch and gradually becomes thinner as the armature reaches the high-speed stage. The trend aligns with conventional theoretical expectations. Further comparative analysis between the deposition thickness and the current waveform identifies a significant time lag: the maximum deposition layer thickness occurs after the peak of the current waveform. During the high-speed stage, despite the relatively high current amplitude, the deposition thickness decreases rapidly and ultimately disappears. This behavior is attributed to the cessation of armature melting, which halts the further deposition of material onto the rail surface.

A three-dimensional transient electro-magneto-thermo-mechanical coupled model was developed to investigate the thermal response of the rail during launch, incorporating contact pressure, contact resistance, and friction at the armature-rail interface. The results are as follows: (1) In spatial distribution, the rail temperature rises first and then falls along the direction of armature movement, with the peak located in the low-to medium-velocity stage. (2) In spatial heat evo-lution, the temperature transitions from a rapid increase to a plateau stage and then to a gradual decrease. (3) As the launch progresses, Joule heating from contact resistance dominates at the beginning, followed by frictional heating, contributing approximately 62% and 38% of the total heat input, respectively. The peak rail temperature rises from 293 K to 887 K. The model in-corporates material thermal softening. This effect, combined with electromagnetic force attenu-ation, leads to a progressive decrease in contact pressure. The reduced pressure, in turn, results in higher contact resistance and intensifies localized heating, which ultimately accelerates the overall rail temperature rise. These findings clarify the coupling between current and heating sources, providing theoretical insight and numerical support for thermal protection design and service life assessment of electromagnetic launchers.