Electromagnetic Acceleration Research Articles

Marine vibrator using electromagnetic acceleration

Abstract Optimizing the low-frequency performance of the vibrator is an important direction for the development of marine vibrators. In order to solve the problems of high resonance frequency, small low-frequency displacement and difficulty in generating low-frequency signals of marine vibrators, this study proposed a strategy of high-frequency and low-frequency distributed vibration. In the low-frequency part, electromagnetic acceleration is innovatively combined with the vibrator, and the Ansys Maxwell finite element simulation software is used for analysis. In the high-frequency part, the traditional moving coil vibrator structure is used, and experimental verification is carried out in the anechoic tank. The simulation results show that the low-frequency part of the marine vibrator using electromagnetic acceleration can achieve low-frequency vibration, and the vibration is still relatively stable. The experimental results of the anechoic tank show that within the test frequency band, the sound source level generated meets the requirements of seismic exploration for high-frequency vibrators. This study uses the frequency segmentation strategy to improve the overall working efficiency of the vibrator and provides new ideas for the design of marine vibrators.

Experimental investigation of the electromagnetic acceleration mechanisms in an applied-field magnetoplasmadynamic thruster

Abstract The high specific impulse and efficiency of the applied-field magnetoplasmadynamic thruster make it one of the most promising electric thrusters in deep space exploration. However, the crucial electromagnetic acceleration mechanisms are still not clearly investigated, which limits performance improvement. The electromagnetic acceleration mechanism is closely related to the current path and magnetic field distribution in the plume. Experiments are conducted using a water-cooled Hall probe in the steady-state applied-field magnetoplasmadynamic thruster plume. The radial, azimuthal and axial magnetic fields are measured, then the current density and Lorentz force density are calculated. The results show that the outflow current accounts for 63% to 82% of the thruster discharge current depending on the strength of the applied magnetic field. Moreover, the outflow current can extend the range of electromagnetic force action, which in turn increases the effect of electromagnetic acceleration. The radial Lorentz force is numerically dominant, and the combined effect of the radial Lorentz force and axial Lorentz force is to compress the plasma toward the axis. In electromagnetic acceleration, Self-field contributions are less than 5%, while E × B acceleration constitutes -12.2-21.2%, and Diamagnetic acceleration dominates at approximately 76.7-90.5%. Finally, a method for evaluating the rotational velocity was presented based on the MHD equations. The centrifugal force was then calculated by combining this with the plasma density. At the thruster outlet, the centrifugal force is significant and cannot be ignored in comparison to the radial Lorentz force.

Adaptive control of magnetic levitation system based on fuzzy inversion

A novel adaptive tracking controller for magnetic levitation systems (MLS) is developed. The controller is based on a special adaptive control scheme incorporating fuzzy model of electromagnetic acceleration enabling fast and accurate fuzzy inversion. The controller ensures accurate tracking of any smooth desired position signal, despite unknown MLS parameters. The closed-loop system stability, in the sense of uniform ultimate boundedness (UUB) of error trajectories, is proved using Lyapunov approach. The closed-loop system performance is investigated during numerical experiments. Finally the proposed controller is verified by successful implementation on a DSP board controlling a typical magnetic levitation ball system. Performed tests and experiments demonstrate that the proposed control technique is robust against discretization and unknown MLS model parameters, provides high tracking accuracy, is easily implementable, and simple to tune.

Boosted luminescence of chiral nanophosphors with circularly polarized luminescence

Achieving strong circularly polarized luminescence (CPL) responses in chiral inorganic materials is a challenge. Our study reports a synthesis of bismuth bromide oxybate-based inorganic nanomaterials that have been modified with chiral sugar alcohols (D/L-BYE) co-doped with Er3+ and Yb3+. Chiral molecules are used as inducers to preferentially grow the materials towards specific chirality. The Er3+, Yb3+ co-doped chiral sugar alcohol modified BiOBr has stronger luminescence intensity of up-conversion and the near-infrared second region (NIR II) under the excitation of 980 nm. It has been demonstrated that the enhancement of near-infrared and visible luminescence is attributable to electromagnetic field-induced acceleration of radiative excursion and Mie scattering effects. The study proposes a novel approach to simultaneously enhance the up/down conversion luminescence of chiral inorganic nanomaterials doped with rare earth ions. Meanwhile, this material exhibits strong circularly polarized luminescence properties in the visible range, which has great application potential in chiral optics and other fields.

Enhancement of the electrostatic–magnetic hybrid thrust performance using a stagnant ring

Electrostatic–magnetic hybrid ion acceleration has been researched to realize high-thrust density and efficient thrust operations. In this study, a newly designed stagnant ring (SR) was installed in an electrostatic–magnetic hybrid thruster with the nominal anode inner radius of 40 mm to improve the thrust performance, and the effects of SR on the thruster operation of xenon propellant were analyzed. During constant-discharge-voltage operations, the discharge current increased with both electrically conductive (copper) and non-conductive (ceramic) SR materials, yet the thrust increased only with the copper SR, which was equipotential to the anode. At lower values of the radial width (H) of the copper SR, the thrust and discharge current were almost dominated by the propellant flow rate from the anode surface. However, the contribution of the propellant flow rate from the cathode tip on the thrust and discharge current became significant when H ≥ 9 mm. The thrust coefficient in electromagnetic acceleration form exhibited a maximum value at H = 9 mm, whereas that in electrostatic acceleration form monotonically increased when H ranged from 0 to 20 mm. The highest thrust efficiency was obtained at H = 12 mm. The study findings indicate that installing a conductive SR can effectively enhance the thrust performance in electrostatic–magnetic hybrid thrusters.

Electromagnetic Acceleration: Principles, Applications, and Challenges

Electromagnetic Acceleration: Principles, Applications, and Challenges

Current Sheet Evolution in a Planar Inductive Pulsed Plasma Thruster

Abstract The evolution of the current sheet is fundamental to the understanding and operation of planar inductive pulsed plasma thrusters. Methods for experimentally determining the time-varying mutual inductance and plasma resistance associated with the current sheet are presented. From these, time-histories of the resistive heating in and electromagnetic acceleration of the sheet are found. Analysis of experimental data obtained from a compact, low discharge energy inductive pulsed plasma thruster shows that current sheet evolution is well described by three phases: ionization, formation, and acceleration. Evidence is provided for the plasma current and resistive heating becoming localized near the upstream edge of the current sheet as the sheet forms. The influence of initial propellant density and pre-ionization on the characteristics of the sheet are examined. Both higher propellant densities and increased pre-ionization are found to produce current sheets which exhibit greater magnetic impermeability. Higher densities cause the sheet to form closer to the coil face, improving coupling, while stronger pre-ionization leads to more rapid resistive heating, causing the sheet to form earlier in time.

Improved electro-mechanical model and energy conversion efficiency analysis of pulsed plasma thrusters

The primary electro-mechanical model is developed for the acceleration kinetics of electromagnetic railguns. Pulsed plasma thrusters (PPTs), whose operation principle is similar to that of electromagnetic railguns, generate thrust via electromagnetic acceleration of plasma. Therefore, the electro-mechanical model serves as a valuable analytical tool to explore the mechanisms of energy conversion and thrust generation of PPTs. In fact, a PPT initiates discharge at its propellant surface and then ejects the discharged channel away to form accelerated plume. During the acceleration, the plasma channel assumes a curved shape, which is different from the flat sheet shape. The curved geometric shape of PPT discharge channel makes the flat current sheet model currently used in the electro-mechanical models inherently flawed. In this paper, a two-dimensional (2D) curved current sheet model is proposed to improve the PPT electro-mechanical model, by referring to the curved morphology of PPT discharge plasma channels. No matter what is the real geometry of the 2D current sheet, the Ampere force on discharge plasma channels and corresponding kinetics can be derived to obtain final kinetic energy of discharge plasma channels. As a result, the relation between the kinetic energy and the inductance of PPT discharge circuit is obtained and expressed as <inline-formula><tex-math id="M6">\begin{document}$ {E}_{{\mathrm{k}}}=\displaystyle\int _{0}^{{t}_{{\mathrm{e}}{\mathrm{n}}{\mathrm{d}}}}{i\left(t\right)}^{2}\frac{{\mathrm{d}}{L}_{{\mathrm{e}}{\mathrm{q}}}\left(t\right)}{{\mathrm{d}}t}{\mathrm{d}}t $\end{document}</tex-math></inline-formula>. To determine the inductance as a temporal function, an algorithm for the inductance is proposed in which time-segment fitting of PPT discharge waveforms is adopted. Moreover, based on the temporal function of the inductance, PPT discharge waveforms can be simulated by using the ODE45 solver of MATLAB with high fitting goodness. So far, a calculation scheme for the kinetic energy of PPT plumes and simulation code for PPT discharge waveforms have set up based on the improved electro-mechanical model. To verify the improved model and the corresponding calculation scheme, the PPT prototype is used to evaluate its energy conversion efficiency. The results show that the model enables elucidating the low PPT electro-mechanical efficiency, which is attributed to the partition limitation of PPT energy to electromagnetic acceleration process. Accordingly, a possible exploration routine for elevating PPT electro-mechanical efficiency is suggested.

Механическое взаимодействие метаемого тела со стенками канала рельсового электромагнитного ускорителя. Численное решение

The vibration of the accelerator rails under the action of electromagnetic forces, the right boundary of which is moving along with the armature along the barrel bore, is considered. The rail accelerator is simply considered as a Bernoulli-Euler beam of finite length, lying on a viscoelastic foundation, with cantilever support from the side of the accelerator breech. The rail vibration is described by a differential equation in partial derivatives of the fourth order in coordinate and the second order in time. The equation is solved numerically by combined method: finite differences in time and finite elements in coordinate. A comparison of the results of numerical calculations with an analytical solution showed that the developed code evaluates the behavior of the rail well under the influence of an EM load moving along its length along the entire trajectory of the accelerated body. Using the developed code, the influence of the current profile in the accelerator circuit and the foundation parameters on the dynamics of bending waves arising and propagating in the rail, the position and magnitude of the maximum rail deflection was studied. It is shown that it is possible to select a current profile that minimizes the rail accelerator deflection during acceleration. It is also found that the choice of the optimal current profile has no less effect on the maximum rail deflection than improving the parameters of the accelerator foundation. The calculation results may be useful in the design of an electromagnetic rail accelerator.

Numerical calculation of an electromagnetic accelerator for the needs of the ISS

The article considers the possibilities of using an electromagnetic accelerator in the international space station. First of all, to launch nanosatellites and remove waste products. As a launch vehicle it is proposed to use a ferromagnetic head, which is accelerated by electromagnets. A scheme for charging capacitors from solar batteries through a flyback converter is proposed. A computer model based on the multiphysical connection between mechanics and electromagnetism has been created. The mathematical model was validated in an axisymmetric setting by comparing the numerical and analytical calculations of the magnetic induction. On the basis of theoretical ideas about the efficiency, the initial values of the capacitance of capacitors were obtained. An optimization technique is presented on the example of changing the capacitance of the capacitor and the length of the coil with a certain step. Substituting the speed of the ferromagnetic head departure from the previous coil as the initial speed in the subsequent calculation allows to determine the time of flight of each stage of the accelerator system and programmatically set the delay time for the discharge of the corresponding capacitor. The numerical calculations presented in this article make it possible to optimize the design of an electromagnetic accelerator and get rid of unnecessary elements such as photo sensors. That will provide an increase in efficiency and, accordingly, the safety of space flights.

Enhancement of Electromagnetic Scattering Computation Acceleration Using LSTM Neural Networks

This paper presents the electromagnetic long short-term memory neural network (EM-LSTMNN) approach to accelerate radar cross-section (RCS) calculations in optimizing low RCS for electrically large targets. The proposed method converts the conventional electromagnetic numerical calculation into an efficient numerical calculation using the LSTM neural network, resulting in a significant improvement in RCS computation speed. To assess the effectiveness of this approach, a downscaled model of a large-sized ship is employed as the target for low RCS optimization. Each modification made to the target’s mesh data during the optimization process is stored in the dataset as a new element. As the ship scaling model undergoes modifications during the optimization process, the new mesh data are recorded, thus adding a new element to the dataset at each time step. This forms a time series representation of the mesh model. By utilizing the dataset collected throughout the optimization process, the proposed EM-LSTMNN model is trained using data-driven approaches, with a training time of approximately 106 s. It is worth noting that this training time is significantly smaller compared to existing methods that employ fully connected neural networks. The performance of the proposed approach is demonstrated by comparing the RCS calculation results obtained through this method with those obtained through traditional electromagnetic simulations.

A Portable Tunnel Electromagnetic Impulse Shock Source.

Early seismic prediction in tunnels has become a necessary task to prevent construction risks. The type and performance of the seismic source are crucial factors that affect its efficiency and prediction accuracy. Among the existing main types of tunnel seismic sources, both explosive and spark sources require pre-drilling and pose safety hazards. In addition, explosive sources pose a risk of damage to tunnel structure walls. Spark sources must be used in a water medium. Artificial hammer sources have weak energy and short prediction distance. This paper proposes a portable tunnel electromagnetic impulse shock source that overcomes the deficiencies of the aforementioned seismic sources. This paper elaborates on the design and working principle of the electromagnetic impulse shock source, and analyzes the electromagnetic force exerted on the hammer body during acceleration. Through finite element simulation, this paper analyzes the multi-physical field changes of the entire electromagnetic acceleration system. Meanwhile, combining experimental testing, the design parameters and energy of the seismic source are optimized to finally design a portable electromagnetic impulse shock source. The engineering measurement data results show that the seismic source can stably generate an output energy of 1500 J, and the overall weight of the seismic source does not exceed 40 kg, with a single shot time less than 30 s and an effective prediction distance over 100 m. This work has significant practical value and superiority.

Electromagnetic Acceleration of Laser-Induced Plasma

Electromagnetic Acceleration of Laser-Induced Plasma

Launch parameters of a lunar ice payload traveling via electromagnetic mass accelerator

This paper describes a solution for procuring propellent needed for future space exploration missions based on the Lunar Electromagnetic Mass Accelerator (LEMMA) concept analyzed by McNab and McGlasson. This study examined the feasibility of using an electromagnetic launcher (EML) to transport raw materials used in propellent production from the lunar south pole to the National Aeronautics and Space Administration's (NASA) Lunar Gateway. The proposed Gateway space station, to be located in a lunar near-rectilinear halo orbit (NRHO), is a critical part of NASA's Artemis program. Cheaply and efficiently sourcing lunar hydrogen from surface ice to the Gateway would benefit the program's success and future exploration of the solar system. Our study of the launch requirements for a lunar EML payload are described here. AGI Inc's Systems Tool Kit (STK) was used to calculate the required launch azimuth, elevation, magnitude, epoch, and trip duration for a payload launched from the Moon to rendezvous with Gateway. The study shows that it is feasible to conduct a single launch from the lunar south pole that can intercept any point along the Gateway's orbit with variable launch conditions.

An augmented multiphase rail launcher with a modular design: theoretical considerations and development

PurposeThe purpose of this paper is to investigate a novel approach toward electromagnetic launch.Design/methodology/approachThe field of linear electromagnetic acceleration aims at accelerating macroscopic masses (up to several kg) to speeds in excess of 2 km/s. This can be achieved using accelerators of the railgun type. The innovation of this work lies in the use of multiphase current instead of the classically used quasi-direct current (DC). The approach taken is to work out in a first step the potential performance of such a configuration, for example, by showing that a constant propulsive force can be realized. Next, the necessary changes for the system setup were carefully analyzed. Both the accelerator and the power supply have to be considerably modified with regard to the classical approach.FindingsThorough analysis of the electromagnetic behavior of the launcher including nonlinear effects lead to an innovative system design which is considered to be the main finding of the work presented here. Moreover, a prototype was build. The preliminary experimental results obtained are in very good agreement with corresponding simulations validating the underlying modeling approach.Research limitations/implicationsFor the purpose of this paper, power levels of only 450 kVA are considered. However, this research can be used to design more powerful devices in the future.Originality/valueWhile DC powered railguns are modeled very well in a variety of papers, the use of multiphase alternating current is not very well discussed yet. It could be of value for launch scenarios, for which very high speeds are required such as the launch of micro satellites to space.

The Limiting Fusion Gain in High-Performance Z-Pinches

The formation of the spectrum of ions leaving the Z-pinch constriction during its compression is considered in the framework of the thermal mechanism corresponding to collisional regimes at high density. This mechanism refers to the heating of all ions due to compression without consideration of the electromagnetic acceleration of any selected group of ions. It is shown that such conditions can be implemented in relatively high-density regimes in which the product of precompression density and radius is n0a0 ≫ 1024 m–3. Neutron yield is analyzed. Possible parameters of a fusion reactor based on a high-density Z-pinch are estimated and found to be extremely high in terms of today’s technology.

準定常作動2cm級自己誘起磁場型MPDスラスタの推力特性評価

In order to understand the characteristics of the Self-field MPD thruster with a discharge chamber diameter of 2cm, a ground experiment system was constructed and the thrust characteristics were obtained. For the power supply system, a capacitor bank using an electric double-layer capacitor and IGBTs was adopted, and it was confirmed that rectangular discharge current pulses could be output at arbitrary times. In the operation check of the experimental system, the discharge current, discharge voltage, and ion saturation current remained constant during 2ms, confirming the quasi-steady operation of the small MPD thruster for 2ms. Thrust measurement experiments were conducted using argon as the propellant, and a thrust force of 0.9N was confirmed at a maximum discharge current of 2.2kA. The measured thrust was proportional to the square of the discharge current. Therefore, it was confirmed that electromagnetic acceleration was dominant. As the highest propulsive characteristics, a specific impulse of 1800s and a propulsive efficiency of 2.3% were confirmed.

Current distribution and plasma velocity characteristics of parallel-plate accelerator under static pressure

Electromagnetic plasma accelerators which can generate high-density and hypervelocity plasma jets have been widely used in plasma physics research and application fields. An experimental platform of parallel-plate accelerator electromagnetically driven plasma is established in this paper, mainly including a parallel-plate accelerator, a power supply, magnetic probes, photodiodes, a current probe, and an oscilloscope. The current distribution and plasma velocity characteristics of a parallel-plate accelerator under static pressure are studied by using magnetic probe array and photodiode array. The working gas is synthetic air. A mechanical pump is used to pump the vacuum chamber to about 1 Pa, and then synthetic air is injected into the vacuum chamber to a target pressure. The power supply of the parallel-plate accelerator has a sinusoidal oscillation attenuation waveform with a total capacitance of 120 μF and a total inductance of about 400 nH. When the charging voltage is 13 kV, the discharge current is 170 kA and the pulse width is 23.5 μs. The discharge currents are 38, 100, 135 kA, and 170 kA when the pressures are 100, 200, 400 and 1000 Pa, respectively. The current distribution of the parallel-plate accelerator is concentrated, and the discharge mode is consistent with the snowplow mode, when the discharge current is small and the working pressure is high. As the discharge current increases or the working pressure decreases, a diffuse current distribution gradually appears in the parallel-plate accelerator. Two regions are formed, i.e. the plasma front region and the plasma tail region. The diffuse current distribution phenomenon is more remarkable when the discharge current is higher or the working pressure is lower. The plasma front current distribution proportion decreases and the plasma front velocity increases with the increase of discharge current and the decrease of working pressure. However, the plasma velocity proportion increased is much lower than the discharge current proportion increased or working pressure proportion decreased. When the discharge current increases from 38–170 kA, the plasma velocity increases from 25.0 km/s to 33.6 km/s, with the velocity increment being only 34.4%. The plasma front region is subjected to both the Lorentz force and the thermal pressure of the plasma tail region.

Experimental layout for the direct measurement of electromagnetic shower acceleration in an oriented crystal scintillator

Progress in experimental high-energy physics has been closely tied to developments of high-performance calorimeters. Since their invention, crystal calorimeters have consistently achieved the best resolution for measurements of the energies of electromagnetic (e.m.) particles (electrons and photons). Recently, we experimentally demonstrated the possibility of significantly accelerating the e.m. shower development inside lead tungstate (PWO) crystal when the incident beam is aligned with the crystal axes within some tenths of a degree. Here, we present the innovative photodetection system, based on Silicon PhotoMultipliers, implemented for the direct measurement of the scintillation light enhancement in case of beam aligned to the main crystal axes, along with its characterization performed with cosmic rays at the Insulab laboratory (Insubria University, Como). In 2021 we performed a test at H2 beam line of CERN SPS with a hundred-GeV electron beam with two PWO samples (1 and 2 X0 thick) directly coupled with SiPMs. Since the angular acceptance of the crystal strong field depends weakly on particle energy, while instead the decreasing of the shower length remains pronounced at very high-energy, a crystal calorimeter based on oriented crystals would feature a consistent compactness enhancement while rivaling the current state of the art in terms of resolution in the range of interest of present and future forward detectors, beam dumps for light dark matter search and source-pointing space-borne γ-ray telescopes.

ICARUS: in-situ studies of the solar corona beyond Parker Solar Probe and Solar Orbiter

The primary scientific goal of ICARUS (Investigation of Coronal AcceleRation and heating of solar wind Up to the Sun), a mother-daughter satellite mission, proposed in response to the ESA “Voyage 2050” Call, will be to determine how the magnetic field and plasma dynamics in the outer solar atmosphere give rise to the corona, the solar wind, and the entire heliosphere. Reaching this goal will be a Rosetta Stone step, with results that are broadly applicable within the fields of space plasma physics and astrophysics. Within ESA’s Cosmic Vision roadmap, these science goals address Theme 2: “How does the Solar System work?” by investigating basic processes occurring “From the Sun to the edge of the Solar System”. ICARUS will not only advance our understanding of the plasma environment around our Sun, but also of the numerous magnetically active stars with hot plasma coronae. ICARUS I will perform the first direct in situ measurements of electromagnetic fields, particle acceleration, wave activity, energy distribution, and flows directly in the regions in which the solar wind emerges from the coronal plasma. ICARUS I will have a perihelion altitude of 1 solar radius and will cross the region where the major energy deposition occurs. The polar orbit of ICARUS I will enable crossing the regions where both the fast and slow winds are generated. It will probe the local characteristics of the plasma and provide unique information about the physical processes involved in the creation of the solar wind. ICARUS II will observe this region using remote-sensing instruments, providing simultaneous, contextual information about regions crossed by ICARUS I and the solar atmosphere below as observed by solar telescopes. It will thus provide bridges for understanding the magnetic links between the heliosphere and the solar atmosphere. Such information is crucial to our understanding of the plasma physics and electrodynamics of the solar atmosphere. ICARUS II will also play a very important relay role, enabling the radio-link with ICARUS I. It will receive, collect, and store information transmitted from ICARUS I during its closest approach to the Sun. It will also perform preliminary data processing before transmitting it to Earth. Performing such unique in situ observations in the area where presumably hazardous solar energetic particles are energized, ICARUS will provide fundamental advances in our capabilities to monitor and forecast the space radiation environment. Therefore, the results from the ICARUS mission will be extremely crucial for future space explorations, especially for long-term crewed space missions.