Electromagnetic Launch Technology Research Articles

High-Voltage High-Frequency Charging Power Supply Based on Voltage Feedback and Phase-Shift Control

With the rapid development of the electromagnetic launch technology, the performance requirements for the charging power supply are increasing. To control the charging rate accurately and get the steady load voltage, a phase-shift control system was designed. This system adopted the control method which regulates the phase angles of the driving pulses by calculating the relationship of the voltage feedback and the preset charging time. According to the topology and application requirements of a high-voltage high-frequency charging power supply (HVHFCPS), a simulation platform based on the physical security information management software was set up. A prototype of HVHFCPS based on voltage feedback and phase-shift control was developed. The experimental results show that the load voltage can be controlled accurately.

Design and Testing of a 10-MJ Electromagnetic Launch Facility

For basic research on electromagnetic launch technology, the Beijing Institute of Special Electromechanical Technology has initiated a program focusing on the design and testing of a 10-MJ electromagnetic launcher facility with the cooperation of Nanjing University and the Institute of Electrical Engineering, Chinese Academy of Sciences. The facility will consist of a 10-MJ prime energy, a 6-m-long railgun, and a control system. A 3.2-MJ pulse power unit (PPU) with 32 100-kJ modular PFN units has been completed and tested, and its prime energy can be easily extended to 10 MJ. A 6-m-long railgun has been built, which can be easily cut into a 4-m-long railgun by which many firings have been done with the new PPU. Construction and testing of the whole facility are being continued.

Some Aspects Concerning the Design of Multistage Earth Orbit Launchers Using Electromagnetic Acceleration

This paper reports on reflections undertaken to establish a possible multistage space-launch system based on the use of combined electromagnetic and rocket launch technology. It is assumed that the direct access to space is not possible using a single-stage system only, since for such a system, muzzle velocities of approximately 10 km/s are required. Multistage chemical rockets have been successfully used for Low Earth Orbit missions. They are now a mature technology; continued system efficiency improvements are expected to yield only marginal progress. Alternative technology paths, such as the Lorentz rail accelerator (LRA), hold the potential for considerable improvements in first-stage efficiencies compared to rocket systems. Such unconventional solution has serious consequences for the accelerator and payload carrier design. In the first part of this paper, some general aspects (size, forces, energy, and power) of an electromagnetic launcher, which could be able to achieve the required muzzle momentum for such a mission, are discussed. More specifically, the design of such a launcher with respect to the type of electromagnetic LRAs (known also as railguns) and to the armature technology is considered, and also, some of the interstage aspects of such a system are investigated. Special attention is paid to solutions increasing the launch efficiency of the electromagnetic launcher. The second part of this paper considers possible design properties of the rocket carrier (booster and kickoff stage). Propulsion system, structure under high acceleration, thermal protection system (TPS), carrier aerodynamics, and flight mechanic properties are analyzed. The performed analysis confirms that the rocket carrier can be realized with the present technology within the next decade. The conclusion is valid under the assumption that a start velocity from a ground-based electromagnetic LRA is limited to about 4.5 km/s if an adequate TPS is applied. At higher velocities, the extreme heat loads destroy the payload carrier.

Special Issue on Selected Papers From the EML Symposium

The 95 papers in this special issue were originally presented at the 15th International Symposium on Electromagnetic Launch (EML) Technology, held at the Royal Military Academy (RMA) in Brussels, Belgium, May 17-20, 2010.

Simulations on Elastoplasticity of the Monolithic Aluminum Armature Under the Contact Force

Keeping good contact of the armature-rail interface (ARI) is essential for electromagnetic launch technology. To investigate the contact mechanism of ARI and improve the contact condition, the elastic-plastic deformation of the monolithic aluminum armature (MAA) under the contact force is analyzed. Contact force, contact area, and the distribution of contact pressure are calculated, and several kinds of armatures with different arm lengths are compared under the same conditions. The calculating loads include the pretightening force under the initial preload and the electromagnetic force from the pulse current. The simulation results show that both the contact force and the contact area under the plastic deformation are bigger than those under the elastic deformation, which is due to the higher spring-back force and displacement. A longer arm length can result in better flexibility and lower contact force. The effect of the electromagnetic force versus the contact force is increased with the arm length.

Advances in Electromagnetic Launch Science and Technology and Its Applications

The U.S. continues a broad spectrum of research to provide the scientific underpinnings for electromagnetic launch. These efforts include fundamental research on materials, properties of materials subjected to electromagnetic and thermal stresses, railguns (particularly the rail-armature sliding interface), coilguns, and energy storage and power conditioning. There is also broad and growing interest in novel applications of electromagnetic launch. For example, a supersonic beam of neon atoms have been slowed and stopped, opening the door for investigating the atomic and molecular properties of most of the periodic table of atoms and certain molecules. Research is continuing on magnetic brakes and the more traditional research on the launch of materials to hypervelocities. More recently, the launching of materials into the Earth's orbit or even deeper in space is obtaining renewed interest. Consequently, some attention is being given to the types of materials of projectiles for hypersonic flight. The U.S. Navy has initiated new multidisciplinary university research teams including physics, chemistry, and materials science to develop new diagnostic tools and to provide a more detailed examination of the rail-armature interface. Most significantly, the U.S. Army has elevated its emphasis from electromagnetic launch science and technology development to the operational consequences of long-range precision fires. In concert with the recent U.S. Navy efforts on long-range fires, it is anticipated that the pull of these applications will enable even greater advances in the science and technology of electromagnetic launch.

Research for the Control System of a Pulsed Power Permanent Linear Synchronous Motor

Pulsed power linear motor is the basic power device in electromagnetic launching (EML) technology. When this technology combines with permanent magnetic linear synchronous motor (PMLSM), a pulsed power permanent magnet linear synchronous motor (PP-PMLSM) is generated. In this paper, the analysis of cogging force and thrust characteristic of this type of motor are presented, and the scheme comparison of bilateral magnet arranged by N face S with N face N direction is made, at last, the digital control system of the PP-PMLSM is designed and realized. The system design is simple, and it improves the control effect.

Introduction

The 88 papers in this special issue were originally presented at the 14th International Symposium on Electromagnetic Launch (EML) Technology, held in Victoria, British Columbia, Canada, June 10-13, 2008.

New Steps in EML Research in Russia

The overview summarizes the main electromagnetic activities in Russia since the 13th Electromagnetic Launch Technology Symposium in 2006. This research has been focused on the development and improvement of electric-discharge launchers, railguns, and electrothermal-chemical launchers. Research efforts have been directed toward studying the physical phenomena and processes limiting the attainment of high velocities and life time of launchers. Considerable attention has been paid to solving problems related to material erosion, the manufacture of new materials and their testing in high-current arc discharges and the search for new applications of launchers in science and engineering.

2008 Peter Mark Medal Presentation

The 2008 Peter Mark Medal for outstanding Contribution to Electromagnetic Launch Technology has been awarded to Professor Philip G. Rutberg, academician and director of the Institute for Electrophysics and Electric Power of the Russian Academy of Sciences/

Influence of the critical velocity on deformation of launcher components

Abstract This paper is related to the dynamics of hypervelocity electromagnetic launchers. A projectile accelerating along launcher rails may cross a range of critical velocities and induce structural resonance. As a result, the rails and other components exhibit increased displacements and stress that may affect launcher performance and lead to premature launcher failure. This work is a continuation of our previous studies of the critical velocity and resulting transient resonance that was performed for a notional hypervelocity launcher [Nechitailo NV, Lewis KB. Critical velocity for rails in hypervelocity launchers. In: Proceedings of the 2005 hypervelocity impact symposium. International Journal of Impact Engineering Dec. 2006; 33: 485–495; Lewis KB, Nechitailo NV. Transient resonance in hypervelocity launchers at critical velocities [Selected papers from the 13th Electromagnetic Launch Technology (EML) Symposium, Potsdam, Germany, May 22–25, 2006]. IEEE Transactions on Magnetics Jan. 2007; 43 (No. 1, Part II): 157–162 [1,2]]. Analytical models including Bernoulli–Euler model of a beam resting on an elastic foundation and the Timoshenko and Flugge tube models as well as finite element tools helped to better understand the transient resonant regimes in launcher components and offered insight on how to alter the launching device materials and geometry to reduce the critical-velocity effects. Analysis showed that the various components of a launcher can have different critical velocities and there is a possibility of enhanced group resonance in the assemblies. The resonance in the launcher assembly can be reduced by controlling the bending stiffness of the individual components. Finite element models were used to illustrate the influence of variations in materials of launcher components on the resulting critical velocities, intensity of the group resonance, and resulting maximum displacements and stress.

Progress in Electromagnetic Launch Science and Technology

Electromagnetic (EM) launch science and technology in the United States continues to advance at a significant pace. The computational and experimental tools for understanding the critical physics issues are sufficiently mature that they are being utilized to provide insight and resolution of the remaining major technical challenges. For example, the primary computational electrodynamics code, EMAP3D, is now implemented in a hybrid finite element-boundary element configuration with moving conductors, providing faster computation and increased understanding of these complex systems. An increased focus on railgun tribology and experiments to understand the interface between railgun armatures and the rail surface is providing important insight for improved railgun lifetimes. Control algorithms for counter-rotating pulsed alternators have been developed and validated experimentally with physical scale simulators. Solid-state switches are replacing the more traditional vacuum switches for high-current and high-voltage railgun power sources. Silicon is the material of choice, but silicon carbide shows great promise for reduced size and increased electrical performance. As a consequence of these and other advances, the U.S. Army has initiated an effort to build a power source with a matched pair of counter-rotating pulsed alternators and a cantilevered railgun to accelerate projectiles to 2-MJ kinetic energy. The U.S. Navy has initiated a new effort to launch large projectiles to hypervelocity. Because of the large naval platform, the size and weight of the power source are not significant issues for the U.S. Navy, whose primary interest is in providing precision fire support to ranges in excess of 200nmi (500 km). The critical technical issues in implementing this application for the Navy are railgun bore lifetime and high-acceleration-tolerant guidance and control. This paper highlights the recent major achievements in hypervelocity physics, pulsed power, and railgun lifetimes that provide the critical science and technology underpinnings for the Army and Navy EM gun programs

Introduction

This article discusses the 13th International Symposium on Electromagnetic Launch (EML) Technology. Eighty-five selected papers from the conference are published in this issue.

Overview of Some Recent EML Research in Russia

The overview summarizes the main electromagnetic activities in Russia since the 12th Electromagnetic Launch Technology Symposium in 2004. This research has been focused on the development and improvement of electro-discharge launchers, railguns, and electrothermal-chemical (ETC) launchers. Research efforts have been directed toward studying the physical phenomena and processes limiting the attainment of high velocities and operational resources of launchers. Considerable attention has been paid to solving problems related to material erosion, the manufacture of new materials and their testing in high-current arc discharges, and the search for new applications of launchers in science and engineering

2006 Peter Mark Medal Presentation

The 2006 Peter Mark Medal for Outstanding Contribution to Electromagnetic Launch Technology has been awarded to Mr. Alexander Zielinski of the Propulsion Science Branch of the Army Research Lab, Aberdeen, Maryland.

A Model for Computing Equation of State of Plasma of the FST Injector of Electromagnetic Railgun

Fast shock tube (FST) is a launcher, which can be used as the injector of electromagnetic railgun, and its working fluid often chooses the inert gas, which is ionized to high-temperature and high-pressure plasma by strong shock wave in the process of launching. This paper presents a simplified model of computing equation of state (EOS) of plasma of the FST injector; we gain the analytic function of the ionization potential versus the average degree of ionization by fitting the numerical results of the ionization potential calculated with Thomas-Fermi (TF) statistical model. Combined the function of the ionization potential with the Saha equation of multiple ionizations, we establish a simplified model for calculating the average degree of ionization, which is the analytic function of the average degree of ionization of argon versus temperature and density in local thermal equilibrium (LTE) case. The curve of pressure p versus specific volume V in argon plasma is calculated according this simplified model, and the results calculated are basically in agreement with the several sets of experimental date and the results calculated with the Saha-equation theory in the high-density region. This simplified model can also be used to calculate the equation of state of plasmas mixture and is expected to have a wider use in the field of electromagnetic launch technology involving the strongly ionized plasma

Analysis of Force Distribution Acting Upon the Rails and the Armature and Prediction of Velocity With Time in an Electromagnetic Launcher With New Method

An advanced high-power electromagnetic launcher (EML) improves performance by as much as 30% over a conventional launcher. Electrical energy is the main driving source for the electromagnetic launcher. In recent years, much effort has been focused on the improvement of EML technology. To date, most studies involving electromagnetic launchers assume an estimated velocity profiles and calculate the force acting upon the armature with an approximation. The purpose of this study is to calculate the force distribution (thrusting and vertical forces) acting upon the armature. In addition, a more accurate method is utilized to determine the velocity variation with respect to time and position. In our formulation of governing, nonlinear differential equations, Maxwell equations are applied to the rails and the armature. The current field distribution of the rails and the armature as well as the total force distribution acting upon the armature are calculated while temperature and thermophysical properties of the armature and the rails are varying. Finally at different time the velocity variation is determined. A finite-difference code based on the alternative directional implicit method is utilized to solve the nonlinear governing differential equations. As a result of this method we can predicate a more precise velocity, acceleration, and gradient induction (L') at different time steps

Electromagnetic launch science and technology in the United States enters a new era

Electromagnetic launch science and technology in the United States is on the threshold of a major new advance in its development. Significant developments in hypervelocity electromagnetic launch and in hypervelocity high-G guidance and control components have provided the impetus for exploring advanced electromagnetic weapon systems capable of providing revolutionary new capabilities. These systems include the electromagnetic launch of aircraft from Navy aircraft carriers, hypervelocity electromagnetic guns on ships to provide protection and to launch guided projectiles to extraordinary ranges, and lightweight ground combat vehicles propelled by hybrid electric power protected by electromagnetic armor and capable of defeating advanced armor targets with lightweight hypervelocity penetrators from electromagnetic railguns. This presentation will summarize many of the technical advances leading to the decision to implement these new engineering efforts.

Keynote Remarks at the 12th Symposium on Electromagnetic Launch Technology

Presents the introductory welcome message from the conference proceedings. May include the conference officers' congratulations to all involved with the conference event and publication of the proceedings record.

Widely developing electric launch technology in China

It can be seen from the 20 abstracts submitted to the 11th Electromagnetic Launch (EML) Technology Symposium by five Chinese departments, that is developing extensive electric launch technology. At least four Chinese ministries support the experimental research on electrothermal launch technology, electromagnetic rail launch technology, coil launch technology, and reconnection launch technology, respectively. There is also research being done on the electric armor and electromagnetic pumping technologies that are correlative with the electric launch technology. Some other ministries have established various foundations to support the theoretical research on electric launches. In addition, international cooperation in science and technology is under way. For example, we are currently doing cooperative experimental research on the electromagnetic launch with some foreign experts, and coauthoring a book titled Physics of Electric Launch (English version). emphasizes the cultivation of successors on the electric launch technology. Since the first Peter Kemmy Memorial Student Scholarship was awarded to a Chinese young scholar in 1998, more universities have begun to offer courses in electric launch technology for undergraduates as well as for Master's and Ph.D. degree students. Furthermore, some postdoctoral researchers are researching electric launch technology in their theses. To organize and unite national researchers on electric launch technology, encourage more people to enter the field, and stimulate further development, recently we have initiated to establish the China Electromagnetic Launch Society. The establishment of the Society makes it convenient for us to accept the lead of the international EML Permanent Committee, and to offer an opportunity of academic exchange and cooperation from home and abroad.