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ASELSAN Inc. has been conducting experimental research on electromagnetic launch technologies since 2014. The first prototype, EMFY-1, has 25 $\text {mm} \times 25$ mm square bore and 3-m-length rails. In addition, two capacitor-based pulsed-power supplies (PPSs) with 1- and 4-MJ stored energy are built to supply launcher. During the design process of EMFY-1, a 3-D finite element (FE) model has been developed to simulate the electromagnetic and mechanical aspects of the railgun. This paper presents the simulation and experimental results of EMFY-1 with C-type aluminum armature. FE model, developed using COMSOL Multiphysics, includes both launcher and the PPS system. In addition to the velocity and position of the armature with respect to time, it is possible to observe the magnetic field, current density distributions and breech voltage using the FE model. In the experiments, pulse currents of the PPS modules, breech, and muzzle voltages are measured. The velocity of the projectile is measured using the B-dot probes. In this paper, two experiments of EMFY-1 will be presented. In the first experiment, the launch package with 42-g total mass is accelerated to 2778 m/s, and in the second experiment, the launch package with 130-g total mass is accelerated to 1560 m/s. The simulation results of the proposed FE model are compared with the experiments. It is observed that there is a good agreement between experimental and simulation results. [ABSTRACT FROM AUTHOR]

Reluctance coilgun (RCG) is a special coilgun which uses solid ferromagnetic material instead of induction coil as projectile. RCG has shown great advantages and potential in the application of antiterrorism weaponry due to its simplicity, reliability, and excellent controllability. As a compact lightweight pulsed-power supply (PPS), the compensated pulsed alternator (Compulsator) will play a key role in promoting this kind of electromagnetic weapon into practical applications. Focused on a specific RCG which has conductive rails and brushes, this paper deduced the electromagnetic force analytical formula by using the virtual displacement principle and researched the feasibility of the electromagnetic launch design scheme which uses compulsator as the PPS of the RCG system by co-simulation method. Finally, this paper finished tests of the system by taking advantages of a small demonstrative RCG and a scale-model prototype of the compulsator. The results indicate that the design scheme is completely feasible. [ABSTRACT FROM PUBLISHER]

In 2016, Hanwha Defense Systems Corporation commenced an electromagnetic launcher program to develop the next-generation “cold-launching” missile launcher system. This system is based on multistage induction coilguns with advantages such as controllability of energy transfer, reusability, and noncontact between the armature and the stators. The system requirement is to launch missiles to a height of 20 m with weight ranging from hundreds of kilograms to several tons. This paper presents the design, fabrication, and experiment results of a laboratory-scale electromagnetic launcher to demonstrate the feasibility of an electromagnetic launcher for heavy missiles. The effectiveness and performance of an electromagnetic launcher developed to launch heavy missiles have been demonstrated by accelerating a 21.68-kg projectile to 20 m/s. [ABSTRACT FROM AUTHOR]

This paper presents a novel three-coil reconnection electromagnetic launcher (TCREL). Analytical calculations and simulation results indicated that not only does this model possess a higher structural strength, but also the launching efficiency is improved effectively compared with that of the traditional reconnection electromagnetic launcher (REL). In addition, take the TCREL model as an independent module; a toroidal REL (TREL) model can be obtained after several modules are uniformly placed and fixed around the circumference. The TREL model can reduce the magnetic flux leakage among driving coils, and further improves the launching efficiency. To verify the conceptual feasibility, two-stage TCREL and REL models were built and tested. The experiments demonstrate that the TCREL model possesses better launching performance than does the REL model; the former can obtain the desired launching efficiency of 15.818% but the latter only 8.248% in the contrast experiment. The experimental results are also in accordance with the simulation results. [ABSTRACT FROM AUTHOR]

Electromagnetic induction coilgun systems have been receiving great attention, recently, due to the advantage of noncontact between the stator and armature coils. Several studies present the simulation and analysis of the coilgun system by using the finite-element method. However, there are still deficiencies in current modeling studies of the coilgun system. This paper presents a design of a multistage pulsed power induction coilgun system using the Taguchi method to maximize its efficiency and reduce the time and cost of the design process. A coilgun system is analyzed and designed using a state-space equation system. The Taguchi method is applied in order to evaluate and determine the geometric variables, the layer, turn layer numbers for both the stator and armature coils, and the trigger positions of each stage. Then, a 2-D finite-element model of the coilgun system using the MagNet program was developed to compare the design and analysis results. The energy efficiency of the three-stage coilgun system is 31.3%, and this is expected to increase with the increase in the number of stages. [ABSTRACT FROM AUTHOR]

This paper presents a new capacitor bank topology for a pulsed power system to improve the efficiency of multistage synchronous induction coilgun. In the proposed method, a switch, such a gate turn-off thyristor, is inserted in parallel to a crowbar diode and load to generate an attractive force between the next stator and the armature. A mathematical model was developed, and finite-element method simulations were conducted to verify the proposed topology. The results show that the proposed method improves the energy efficiency and launch velocity. The improvement in energy efficiency is confirmed from the simulation results of a three-stage synchronous induction coilgun. [ABSTRACT FROM AUTHOR]

Electromagnetic launchers (EMLs) including railguns, helical guns, and coilguns have been proposed for numerous applications. However, the scaling characteristics of EMLs are unknown. This paper examines the nonlinear operating characteristics of EMLs and derives the operating voltage and current scaling relationships as determined by the mass and velocity of the projectile and the length of the launcher. The scaling relationship is derived using the kinetic power relationship common to all types of EMLs. The scaling relationship is expressed as a simple function of the projectile velocity, projectile mass, and launcher length. This paper also defines the impedance of an EML. The accuracy of the scaling relationship and the EML impedance are verified in a comparison with the experimental results of practical EMLs. The effects of resistive losses and inductive energy storage on the scaling relationship are included in the analysis. [ABSTRACT FROM PUBLISHER]

As power supplies, compulsators are popular choices for electromagnetic railguns. In this paper, a two-phase two-axis-compensated compulsator (2P2AC compulsator) with lower internal inductance and higher power density was designed and analyzed. Two-phase armature windings are allocated on the stator, and discharge pulse currents to the load via a rectifier. This arrangement decouples the machine speed from the pulsewidth, thus enables a higher tip speed. Two sets of windings with electrical orthogonal displacement are allocated on the rotor. The bigger one is the field winding that freewheels via a diode and provides the direct-axis compensation during the discharge process, while the smaller one is the short-circuit compensating winding providing the quadrature-axis compensation. The effect of the composition of the $d$ - and $q$ -axis compensation is equivalent to a passive compensation using a continuous conductive shield, which compresses the flux for all rotor positions. Compared with the passive compensation, this arrangement has no conductive path to couple with the field winding due to the orthogonal displacement, thus speeding up the charging process. This paper presents the design methodology of the 2P2AC compulsator, along with its system performance of driving railgun load. [ABSTRACT FROM PUBLISHER]

A multi-turn railgun system is designed to accelerate a massive load of hundreds for kilograms to speeds of several Mach. Generally, conventional railguns operate for a few milliseconds, accelerate loads of several grams to several kilograms with an acceleration of 105 m/s2 to speed of several kilometers per second. Due to the strong limitation of the rail and armature, a conventional railgun is not capable of accelerating massive loads to high speed. Multi-turn railguns and helical electromagnetic launchers have the potential to accelerate massive loads to high speed. In this paper, the design of a multi-turn railgun system is presented. The designed multi-turn railgun has a length of 1000 m, a bore of 500 mm, turns of 30, and propulsive inductance gradient of 0.58 mH/m. The multi-turn railgun is driven by an inexpensive lead-acid battery based power supply in time duration of 2 s. A circuit model for multi-turn railgun and power supply was derived. Simulation results show that the multi-turn railgun is capable of accelerating 500-kg load to a speed of 1000 m/s. The feasibility and main challenges for developing the multi-turn railgun system are discussed. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of coilgun with stepped coil winding was designed. The performance of this structure was investigated and compared to the conventional coilgun with uniform diameter stator coil (UDSC) winding. It can be seen from the results that the trigger position of this new structure moves forward with respect to the conventional coilgun. In order to compare the results, the inductance of the two coils is set to the same. If the initial voltage of the capacitor is lower, as the armature at the optimum trigger position, the muzzle velocity of armature in the conventional UDSC coilgun is relatively larger. Conversely, if the initial voltage of the capacitor is higher, the muzzle velocity of armature in the new structure coilgun is relatively larger. According to the simulation results with the increase of voltage, the difference is more and more obvious. Through the single-stage preliminary experiment in our laboratory, the results were in good agreement with the simulation results. And the trigger position is more forward, so the interaction time between the armature and the coil will be longer. Besides, the coil with stepped structure will increase the efficiency of the coilgun when the voltage level is higher. [ABSTRACT FROM AUTHOR]

Nowadays lunching masses to faraway distances is an important issue. One of important electromagnetic launcher for this purpose is duble-projectil railgun because it can launch synchronously two separated projectiles. It has been obtained before that two-turn railgun have better inductance gradient and performance than simple railgun. Also, self-inductance gradient and mutual-inductance gradient in two-turn railgun depend on the initial position of armatures. In this paper, we want to calculate the inductance gradient of a new structure that we named it plus railgun. The plus railgun has one barrel between two-pair rails by two separated armatures and two pairs of rails are powered by one pulse power at the same time. A 3-D finite-element method is applied to the transient analysis of the magnetic field, current distribution, and the inductance gradient of railguns. Finally, we will compare the parameters of two-turn and plus railguns. [ABSTRACT FROM PUBLISHER]

Multipole field electromagnetic launcher (MFEL) is a new type of coilgun that can produce larger radial magnetic field compared to the axial magnetic field, the axial acceleration force of coilgun mainly come from radial magnetic field. Because of the similarity of the magnetic fields between inner and outer regions of MFEL, this paper proposed a double-armature MFEL. One armature coaxial with the drive coil placed inside of MFEL; the other armature coaxial with the drive coil placed outside of MFEL. A single-stage double-armature MFEL was studied by simulation and experimental methods. The simulation results indicated that the muzzle velocity of the double-armature launch is similar to that of the single-armature launch, and the efficiency of double-armature MFEL is obviously larger than that of single armature. To verify the conceptual feasibility, a small-size single-stage double-armature capacitor-driven MFEL was built and tested. The inner small armature weighs 63.13 g, the outer big armature weighs 88.38 g. The experimental results on single-armature launch show good consistency with the simulation results, but there is a little gap between the experimental results on double-armature launch and the simulation results. The causes of the existing differences are considered to be mainly from the consistency difference between the six driving coils and the mutual influence between the inner and outer armatures. [ABSTRACT FROM PUBLISHER]

We have performed 2-D axisymmetric magnetohydrodynamic simulations for a single stage induction coilgun system and validated the results against in-house experiments. The simulations, besides computing the currents and electromagnetic forces, also capture the associated hydrodynamic phenomena. This paper highlights the importance of appropriate material strength for handling hydrodynamic phenomena and temperature-dependent electrical resistivity model for self-consistent electromagnetic calculations. These are very essential for accurate prediction of armature dynamics and velocity. Inappropriate resistivity model, even in case of no deformations, produced velocity deviation of up to 50% as compared with experiments. Inclusion of appropriate models shows <4\% average deviation when compared with experiments for known armature material (Al6061-T6). For higher energies, predicted armature deformations appear to be in a good agreement with experiments. If material deformation is ignored, velocities get over-estimated. Finally, subsequent to our validation at low energies, an optimized armature profile and dimensions are reported that have allowed our armatures to achieve velocity >200~m/s with single stage operation and 300 m/s with two-stage operations of the coilgun. This paper shows that accurate modeling of Joule heating and armature deformation, along with self-consistent evolution of currents, is essential for coilgun modeling. Although the system is not presently optimized for efficient energy conversion (\sim1.5\%), the performance of induction accelerator at moderate velocity of armature (50–300 m/s) is not only useful for validating our code, but can act as an effective catapult for impact testing of materials. [ABSTRACT FROM PUBLISHER]

In pulsed power supply for electromagnetic launchers, air-core pulsed alternators have obvious advantages to enhance the power and energy densities with a compact and lightweight structure, and it is gradually to be the prime candidate for pulsed power supply. Compared with conventional machines, an air-core pulsed alternator will supply large amounts of energy over millisecond time with a huge current as high as 1 MA and a high voltage reached several kilovolts. Since the short history of the air-core pulsed alternator in China, the related theoretical research is not enough and the fabrication experience is absent. At present, research has shown that the performance of the air-core machine cannot be evaluated by the 2-D method due to the nonexistence of ferromagnetic materials, and it is very necessary to carry out the 3-D analysis by a finite-element method (FEM). This paper will present a 3-D model of the machine according to the accurate geometric size, and the model is used to develop electromagnetic analysis by the FEM and a transient simulation about the no-load EMF is carried out too. In order to understand the mechanism and process of electromechanical energy conversion, it is obviously important to figure out the magnetic field distribution in the machine. Meanwhile, in order to evaluate the strength of the windings, the calculation of electromagnetic forces and torques is developed when the machine drives the electromagnetic rail gun with a current of 1 MA. [ABSTRACT FROM PUBLISHER]

As the most efficient and compact sources in pulsed power supply for electromagnetic launchers, the air-core pulsed alternator can supply a current as high as 1 MA with a voltage reached several kilovolts. The machine performs various functions, such as kinetic energy storage, electromechanical energy conversion, and power conditioning, making the electromagnetic launch system compact and lightweight. But due to the short history of the machine and the absence of fabrication experience in China, the air-core pulsed alternator is still in an exploratory stage, and there are lots of key technologies and problems needed to be researched deeply. Taking technical risks and manufacturing costs into consideration, a seven-phase air-core pulsed alternator has been proposed and the machine is under development. In this paper, operation principles of the electromagnetic launch system are presented in detail. The mathematical models of the seven-phase alternator and the rail gun are introduced. Based on the mathematical models, a simulation model about the electromagnetic launchers is built, and it is useful to help us figure out the operation characteristic when the self-excitation machine drives the electromagnetic rail gun with a 200-g projectile. As a result, it is convincing by simulation to prove the drive current can be as high as 1 MA and the projectile is with a velocity of 2 km/s at the exit. Simultaneously, violent transient situations will be illustrated in this text, such as the electromagnetic torque and the rotor speed. Meanwhile, simulation results can verify the analytical method and present the current and voltage straightforwardly. They also have great significance on choosing the proper high power switching devices. [ABSTRACT FROM PUBLISHER]

The dual representation of MARX (XRAM) pulse current generator with magnetic flux compression effect is a novel circuit for current multiplication, which has the advantages of both meat grinder and XRAM that are basic circuit topologies. It contributes to the multiplication of current in two aspects: first, increasing current by magnetic flux compression and second, the current can be increased by paralleled inductors. Compared with the standard XRAM topology, the proposed circuit topology can realize a larger factor of current multiplication more easily, and is better than the standard slow transfer of energy through capacitive hybrid meat grinder circuit topology in aspects of scalability and modularity. Meanwhile, its energy density is increased significantly, which is advantageous to the needs of actual electromagnetic launch. In this paper, theoretical analysis is done to illustrate the excellent performance of the proposed topology and preliminary experiment was conducted to demonstrate its feasibility. [ABSTRACT FROM PUBLISHER]

The passively compensated pulsed alternator (PCPA) is one of the most competitive pulsed power technologies for future electromagnetic launcher systems. The PCPA is mostly designed for the high pulse repetition frequency military applications, such as the railgun, coilgun, and electrothermal chemical gun. The PCPA is a high-energy and high-power (sub-GW) electrical synchronous generator operating in a fast-transient, short-pulse regime. Due to its low internal impedance during the discharge, the pulsed alternator is capable of extremely high output current, almost two orders of magnitude higher than similar rotating synchronous generators of the same size. This paper has investigated the transient inductance of the armature winding of a PCPA, including the internal inductance and the end leakage inductance. A novel method is proposed to decrease the end leakage inductance in which the end windings are surrounded by totally enclosed conductive shields settled at the stator ends. The analytic formulas of the internal inductance and the end leakage inductance are deduced using the magnetic vector potential method. The concept of end winding shielding can be generalized to other types of compensated pulsed alternators, such as the selective PCPAs and actively compensated pulsed alternators. [ABSTRACT FROM PUBLISHER]

This paper proposed a railgun with sector of circular rails. The center of the sector of circular rails is located at the outside of the railgun bore. The distance between the sectors of two circles is s , opening angle facing outward \theta , the inner and outer radius are also assumed to be Ri and Ro , respectively. The influence of internal curvature of the rails, the rail thickness and the distance between rails on the current density, magnetic flux density, and inductance gradient ( L' ) have been studied and analyzed using finite-element method. First of all, the different values of \theta , s , , and R_{o} are calculated for various values of the area of the railgun bore ( S_{C}) and cross section of the rails ( SR) . The current density, magnetic flux density, and L' have been calculated for different values. The area of the railgun bore is assumed to be 9 and 10 cm ^2 and the area of rails are assumed to be 9, 6, 3, and 1 cm ^2 . In next section, L' is found as a function of s , Ri , and Ro for \theta =90 ^\circ , 120°, 150°, and 180°. Finally, $L'$ is compute for rail thickness equals to one-tenth of bore size and $\theta $ on the interval [180°, 360°]. According to the achieved results it can be observed the behavior of $L'$ in terms of railgun dimensions changes and it is compared with other geometries. [ABSTRACT FROM PUBLISHER]

Railguns use electrical energy to accelerate projectiles to large velocities. The electrical energy for the launching process is provided by a pulsed power unit. A pulsed power unit usually consists of a capacitor, a switching device, a crowbar diode, and a pulse-forming inductance. The pulse-forming inductance is necessary to generate an appropriate current pulselength and amplitude. The idea of the energy storage augmented electromagnetic launcher is to use the magnetic field produced by the pulse-forming inductance to augment the magnetic field between the rails of the launcher. To maximize the augmentation of the magnetic field, it is necessary to place the pulse-forming inductance as close as possible to the rails of the railgun. The additional magnetic field causes not only an increased acceleration of the projectile but also a larger mechanical load of the railgun structure. This requires a reinforced housing compared with conventional railgun housings. In this paper, the design and the experimental setup of a railgun using an energy storage augmentation scheme as well as the results of experiments are presented. The results are compared with the previous results of a nonaugmented railgun configuration. The comparison shows an improvement of the energy efficiency. [ABSTRACT FROM PUBLISHER]

A model is developed to investigate the commutation process of a helical coil electromagnetic launcher (HCEML) structure. When the armature moves, the motion of the projectile coils’ magnetic energy would supply reactive power to move the leakage into and out of the coil windings of the launcher to accomplish the commutation. The energy conversion of the coil electromagnetic launcher can be considered as the process of energy transfer from the back commutation coils to the excited coils and then from the excited turns to the front commutation coils. In this paper, governing equations of the commutation were deduced theoretically, and finite-element model of HCEML was established in ANSOFT MAXWELL. Then a deeper circuit investigation into the overall performance of commutation was carried out by means of PSPICE software. The validity of the theoretical analysis and that of the circuit network model were finally verified by experiments. The results show that during the commutation process, the current of back commutation coils drops to zero with no energy remaining in the internal; the current of front commutation coils and drive–projectile coil system gradually changes to a stable value, which is related to the geometric parameters of the launcher; the drive–projectile coil system releases energy overall that is mainly used to increase the kinetic energy of the projectile; the power supply system has little effect on energy conversion and transformation at the commutating moment and just keeps the voltage and current from decaying due to the impedance and inductance of the launcher system. [ABSTRACT FROM PUBLISHER]

This paper performs the inductance and phase coupling analysis of a tubular permanent magnet machine with transverse flux configuration for electromagnetic launch (EML) applications. Self-inductance and mutual inductance are calculated by employing a frozen permeability finite element technique, and the results are validated by measurement on a prototype machine. The analysis of phase coupling problem is then undertaken, and it has been shown that the tubular transverse flux machine has the merit of magnetic decoupling between phases, and thus shows a brilliant prospect in EML applications. The influence of armature reaction on the inductance is also investigated, and it indicates that at higher current, the inductance fluctuates once instead of twice within one electrical cycle, which is quite different from that in conventional machines. [ABSTRACT FROM PUBLISHER]

In this paper, circuit simulation was chosen as the main methodology to analyze the characteristics of an electromagnetic (EM) rail launcher (or EM railgun) system, and a complex simulation model was proposed, which was not merely built on the static electrical parameters. Moreover, practical physical processes contributed to the system have also been taken into consideration and expressed as electrical parameters. Thus, the description of a relatively complex system could be realized by a comparatively simple manner, and the simulation result is more accurate and reliable compared with the traditional circuit simulation ones with the static electrical parameters. A circuit simulation model of an EM launch system based on PSpice software was built, in consideration of multifactor effects, such as current skin effect, contact pressure, and contact resistance on the contact surface of the armature and the barrel, velocity skin effect, friction drag, and temperature coefficient of electrical resistivity. Simulations were made based on the proposed model as well as the traditional one. Last but not the least, a comparison between the simulation results and the experimental ones was made to verify the accuracy and effectivity of the improved model. [ABSTRACT FROM PUBLISHER]

After preliminary tests using a small 25 mm-caliber electromagnetic launcher, a larger mid-caliber launcher has been designed and fabricated. The launcher has a rectangular bore of 40 mm $\times $ 50 mm, where the rails are separated by 50 mm from each other and are 5.6 m long. To deliver an electrical current to the launcher, a new 4.8-MJ pulsed power supply (PPS) consisting of eight 600-kJ segments has been constructed. The 600-kJ segment is a basic building block of PPS operated independently. It contains a controller, a charger, a safety circuit, and six 100-kJ unit modules. Each unit module in the segment is composed of a 100 kJ capacitor bank, a thyristor switch, a crowbar diode, and a pulse-forming inductor. The modules in a segment are charged to the same voltage, but they are designed to have different triggering times to make a flexible shape of current waveform. The electrical parameters of the PPS were determined through the discharges of the unit modules and those of the rails were measured by launch experiments or short circuit tests at the ends of the rails. Launch experiments have been done using several current waveforms. The current of 1 MA in a few milliseconds accelerated the armatures of several hundred grams in mass to velocities near 2 km/s. In this paper, the design and basic performance of the constructed PPS and the electromagnetic launcher are presented. [ABSTRACT FROM PUBLISHER]

Multipole field electromagnetic launcher (MFEL) is a new type of induction launcher that can produce radial magnetic field. This paper proposed different driving coil connection patterns of MFEL and analyzed their performance through experimental and simulation methods. To verify the conceptual feasibility, a small-size single stage capacitor-driven MFEL was built and tested for the first time. Powered by a 100 \muF capacitor bank charged to 3000 V, the launcher is able to accelerate a 50.4 g projectile to a velocity of 13.3 m/s. Characteristics of MFEL including inductance gradient, driving current, eddy current distribution, and magnetic field distribution were analyzed as well. [ABSTRACT FROM PUBLISHER]