CST EM Studio Research Articles

Numerical Simulation of an Electron Beam for Magnetic Bunch Compressor Commissioning at PITZ

A THz free electron laser (FEL) prototype has been developed at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) for obtaining high intensity radiation for THz-pump and X-ray-probe experiments at the European XFEL. In this development, a magnetic chicane was recently installed to optimize the THz FEL performance. The aim of this study is to investigate the beam dynamics in the chicane for a trajectory commissioning by tracking the electron beam via ASTRA using a 3-dimensional (3-D) magnetic field of the chicane simulated with CST-EM Studio. The simulated results indicate the possibility to obtain a minimum-momentum dispersion of an electron beam after chicane with the high bunches charge of electron beam transportation.

Characterization of magnetic field for loading, trapping and transferring cold atom close to the atom chip’s surface

Atom chips provide flexible technologies for implementing modern concepts in quantum optics, quantum measurement, and quantum information processing. Atom chips are miniature devices that confine, control and manipulate cold atoms using electric, magnetic, and light fields. Due to the shrinkage of scale, arbitrary magnetic traps can be generated from current sources outside the chip’s vacuum compartment, in contrast to a traditional setup. This makes it easy to change trap configurations in an experiment that involves rapid prototyping of quantum states and quantum trajectory designs in free space. In this work, we show relevant parameters needed for transferring a cold atom cloud at the recoil limit from a magneto-optical trap (MOT) to an area close to the atom chip. To create a movable magnetic potential for this transfer, we used the MOT coils and an additional pair of coils in an anti-Helmholtz configuration. The properties of the movable potential were obtained by performing the Computer Simulation Tool (CST EM Studio suite®). Furthermore, an appropriate magnetic trap on a chip is developed, based on the simulation from COMSOL Multiphysics. We used a magnetic field gradient of around 20 G/cm to transport the cold atom with a distance over 20 mm with a temperature gain below 100 micro-Kelvin. The simulation results are based on an atom chip with a size of 2×2 cm2 and a copper wire thickness of 2 mm. The atom chip consists of Z, U and I-shaped wires that generate a quadrupole magnetic field. The resulting field minimum can be made at least 7 mm away from the chip surface.

Search for the optimal means for modelling the electric field of insulators

The article analyses software tools for simulation of electric field of insulators. The necessity of solving this problem is dictated by the fact that inaccuracy of simulation software allows stating that the simulation model cannot be improved correctly due to calculation errors in the program itself. Design features of different types of insulators, first of all, the most widespread and used - porcelain and glass insulators, are considered. The change of electric field in a glass and porcelain insulator operating in an AC network without contamination is described. Numerous calculation methods such as boundary element method, finite element method, integral equation method and others have been analysed. It is revealed, that from the point of view of functionality and expediency of application for solution of field problems relevant to electric power industry the finite difference method and finite element method are the most universal ones. The results of insulator electric field modelling using Ansoft Maxwell, CST EM Studio and Elcut software are given. Among Ansys, FEMLAB, Ansoft Maxwell, CST EM Studio, IES Coulomb and Elcut that were analyzed, the software Ansoft Maxwell and CST EM, where the finite element method is implemented, were chosen to solve the given problem. It was found out, which one of the software complies better with the given requirements as to accuracy (by calculation of error of deviation of mathematical modelling and experimental data) and in terms of the method incorporated in the algorithms of the software. Experimental data are compared with simulation results. The possibility of diagnosing insulators by electric field tension parameters has been revealed.

Finite-Difference Simulation of Eddy Currents in Nonmagnetic Sheets via Electric Vector Potential

The magnetic excitation of eddy currents in thin metal sheets is a mathematically challenging problem with many practical applications. Since the eddy current density is a solenoidal field on a 2-D plane, we may express it as the curl of a separate vector field with only one scalar component. This new field is governed by a unique form of the vector-Poisson equation that is readily solved numerically through standard finite-difference techniques. For the special case of a weakly induced eddy current, the self-inductance terms can be neglected to produce a sparse system matrix that is easily inverted. For a strongly induced eddy current, self-inductance must be included at the cost of a more complex and dense system matrix. The method is validated against the CST EM Studio software suite by producing nearly identical results in only a tiny fraction of the computational time.

Electron beam dynamics in the 3D magnetic field of alpha magnet at the PBP-CMU Electron Linac Laboratory

The electron injector system for a future mid-infrared free-electron laser (MIR FEL) and coherent terahertz (THz) radiation source at the Plasma and Beam Physics (PBP) Research Facility of Chiang Mai University (CMU) in Thailand will consists mainly of a thermionic cathode radio-frequency (RF) electron gun, an alpha magnet, a traveling-wave linear accelerator (linac) structure and two magnetic bunch compressor systems. The detailed study of all components in the injector system is very important for generation of high quality electron beam and radiation. This paper focuses on the alpha magnet, which is used as a magnetic bunch compressor and an energy filter before the beam being accelerated in a post-acceleration linac structure. We report its characteristics and the electron beam dynamics in its three-dimensional (3D) magnetic field distribution that was simulated with the program CST EM Studio 2016. The simulated alpha magnet’s fields are comparable with the measurement data. The beam dynamic simulations in 3D magnetic field were performed by using programs ASTRA and ELEGANT. The simulation results allow us to investigate the influence of the fringe field, the vertical focusing and the space charge effect in the alpha magnet. This is significantly important for electron beam manipulation in the injector system. The study outputs reveal that the proper injection angle in the practical beam operation to compensate the fringe field effect should be 42∘ that is 1.29∘ larger than the ideal injection angle. We also found that the ratio of the vertical focal length to the total path length in the alpha magnet is 0.544, which is independent on the magnetic field gradient. Moreover, the space charge force in the electron bunch leads to the rotation of transverse phase spaces while the beam traverses in the alpha magnet’s field. This effect has considerably small influence on the longitudinal phase space, especially for the beam with a bunch charge not exceeding 0.2 nC.

Microwave measurement of initial properties of ferrites using mode splitting phenomenon by the rod resonator method

This paper proposes an accurate method to calculate the permittivity and permeability of ferrites simultaneously at the demagnetized state. The eigenvalue equations for the resonator model can be obtained by applying the boundary condition of the structure of the resonator at both demagnetized and magnetized states. The complex permeability and permittivity are computed from the measured resonant frequencies and unloaded quality factors of the resonator using the mode splitting phenomenon. To verify the calculated magnetization values, the magneto-static simulation is performed by using CST EM studio based on the measured data of B–H curve. The measured complex permeability and permittivity of the demagnetized ferrite are verified by comparing with cavity perturbation method and statistic equation.

Design, fabrication and test of the steering magnet for the KOMAC beamline

The Korea Multi-purpose Accelerator Complex (KOMAC) is operating a 100-MeV proton linac. The beamline facility of the KOMAC has both a 20-MeV beam and a 100-MeV beam for users. Steering magnets are added to the beamlines to adjust the position of the beam on the target. The uniformity and the harmonics of the magnetic field are computed by using the Poisson code, and the integrated magnetic field is computed by using the CST EM Studio. The designed magnets were fabricated, and the field’s uniformity and the integrated field were measured. The designed and fabricated steering magnets were characterized, and the results are presented in this paper. The results are expected to improve the beam performance, in particular, accurate delivery to the target.

Metallic target material identification examined by the finite element method

The numerical analysis of a gradiometric coil arrangement has been performed and the response of a metallic material in the vicinity of the coil system has been examined. The system has been excited by a bandwidth limited step function, thus the step response of the different target materials can be measured on the gradiometer. The 3D numerical model has been prepared in the CST EM Studio environment and has been solved by the finite element method. The simulations have been executed for different target materials, i.e. aluminum, steel, stainless steel and in order to unveil the specific contribution of the magnetic permeability and the electric conductivity to the step response for four fictive materials. The results show that the step response is an appropriate parameter to distinguish between the target materials and to provide information about the sensor to target distance.

Thermal Analysis of Inductive Coils Array against Cylindrical Material Steel for Induction Heating Applications

This paper presented the heating of inductive coil which is 3 elements array. The induction heating coil improve the variations heating that it is increased the system efficiency. By means of the inductive coil has the diameter of 2, 3 and 4 cm and divide the coil as 2 types. There are the inverses and reverse inductive coil arrays, with heating test by cylindrical steel material. Then, this paper considers the heating efficiency simulation of 2 types by CST EM studio 2009. In addition, the experimental of the inductor heating is use the full bridge inverter circuit, the power of 200 W at 28 kHz resonant frequency. Moreover, the distance between coils is coincided of simulation and experimental results, the inverse type at the diameter of 2 cm can be provide the maximum heater.

Investigation of Magnetic Field Gradient Waveforms in the Presence of a Metallic Vessel in Magnetic Resonance Imaging Through Simulation

We have previously established the ability to characterize eddy currents and their impact on the magnetic fields in metal vessel magnetic resonance imaging applications through comparison with measured data. We now use simulation to investigate the spatiotemporal characteristics of eddy currents and their magnetic fields encountered in metal vessel magnetic resonance imaging that may not easily be experimentally verified. Simulations using CST EM Studio have revealed the impact of an offset in the positioning of the metal vessel in a superconducting magnet bore as well as the consequences of the different amplitude magnetic gradients employed during imaging experiments. Furthermore, we investigate the response of the metal vessel to magnetic field gradients generated from nonplanar and planar gradient coil geometries (encountered in superconducting and permanent magnet-based systems). Establishing the basic electromagnetic properties of the metal vessel in a magnetic resonance sense through simulation permits us to replace our simple metal vessel with a more sophisticated rock core holder design and investigate its properties.

New expression for the current induced in a strip for the fringe field effect in a circular cross-section stripline

The induced current (fraction of the wall current) flowing through a strip is a very crucial quantity in stripline-type pick-ups and kickers. Quantities like the output voltage, coupling impedance and kicker constant depend on the fraction of the wall current flowing through the strip. Due to the fringe field at the side edges of the strip the effective angular width of the strip and, hence, the fraction of the wall current intercepted by the strip is enhanced. This paper presents a calculation, by using CST EM studio, of the fraction of the wall current intercepted by the strip. A correction factor for the effect of the fringe field on the current induced in the strip is also presented. The results obtained through simulations and through a new expression are compared with earlier existing expressions.

Monitoring Change of Body Fluid during Physical Exercise using Bioimpedance Spectroscopy and Finite Element Simulations

Abstract Athletes need a balanced body composition in order to achieve maximum performance. Especially dehydration reduces power and endurance during physical exercise. Monitoring the body composition, with a focus on body fluid, may help to avoid reduction in performance and other health problems. For this, a potential measurement method is bioimpedance spectroscopy (BIS). BIS is a simple, non-invasive measurement method that allows to determine different body compartments (body fluid, fat, fat-free mass). However, because many physiological changes occur during physical exercise that can influence impedance measurements and distort results, it cannot be assumed that the BIS data are related to body fluid loss alone. To confirm that BIS can detect body fluid loss due to physical exercise, finite element (FE) simulations were done. Besides impedance, also the current density contribution during a BIS measurement was modeled to evaluate the influence of certain tissues on BIS measurements. Simulations were done using CST EM Studio (Computer Simulation Technology, Germany) and the Visible Human Data Set (National Library of Medicine, USA). In addition to the simulations, BIS measurements were also made on athletes. Comparison between the measured bioimpedance data and simulation data, as well as body weight loss during sport, indicates that BIS measurements are sensitive enough to monitor body fluid loss during physical exercise.

Static voltage distribution between turns of secondary winding of air-core spiral strip transformer and its application

The static voltage distribution between winding turns has great impact on output characteristics and lifetime of the air-core spiral strip pulse transformer (ACSSPT). In this paper, winding inductance was calculated by electromagnetic theory, so that the static voltage distribution between turns of secondary winding of ACSSPT was analyzed conveniently. According to theoretical analysis, a voltage gradient because of the turn-to-turn capacitance was clearly noticeable across the ground turns. Simulation results of Pspice and CST EM Studio codes showed that the voltage distribution between turns of secondary winding had linear increments from the output turn to the ground turn. In experiment, the difference in increased voltage between the ground turns and the output turns of a 20-turns secondary winding is almost 50%, which is believed to be responsible for premature breakdown of the insulation, particularly between the ground turns. The experimental results demonstrated the theoretical analysis and simulation results, which had important value for stable and long lifetime ACSSPT design. A new ACSSPT with improved structure has been used successfully in intense electron beam accelerators steadily.

Optimal Design of a Highly Compact Low-Cost and Strongly Coupled 4 Element Array for WLAN

A 4 element array of microstrip E shaped patches is designed for use in wireless local area network (WLAN) applications. The operating frequency range is from 3.4 to 3.8 GHz and the gain of the array is more than 13 dB. The main beam direction is normal to the ground plane. Considering the specifications given, the focus is on the reduction of occupied space. This implies the use of an integrated feeding technique in combination with highly coupled array elements. Although the concept was published before, no optimizers were used and the previous design did not meet the 10 dB matching criterion. It is clearly proven that, due to its complexity, this innovating topology can be fully taken advantage of only by designing it using efficient evolutionary optimizers. Both a particle swarm optimization (PSO) and a genetic algorithm (GA) technique are used. During the optimization process, the fitness is evaluated by using a full wave solver based on the method of moments (MOM). It is shown that for these types of structures, a single step optimization procedure is preferred, and PSO outperforms GA. CST EM Studio is used for validation purposes before manufacturing. A prototype array is fabricated and measured.

Electrostatic Field Simulation Study of Nanoparticles Suspended in Synthetic Insulating Oil

Electrostatic field simulations have been performed to investigate the effect of barium strontium titanate (BST) nanoparticle suspensions on electric fields within synthetic oil dielectrics. We predict that by physically integrating nanoparticles of high dielectric constants into the breakdown regime, the self-break jitter in rep-rate oil switches might be reduced. The simulations show that the nanoparticle suspensions generate nonlinear and random electric field enhancements within the oil dielectric and also on the electrode surfaces. The BST nanoparticles have been modeled as perfect spheres which have an approximate dielectric constant of 2000. The oil in the simulation was given a dielectric constant of 2.33 and the electrodes are modeled as perfect electrical conductors with no field enhancements. A comparison is made between simulated electric fields on the surface of the cathode with increasing nanoparticle concentration, radius, and distance from cathode. Effects on capacitance with increasing nanoparticle concentration and radii are also investigated. All electrostatic simulations were performed with CST EM Studio. Preliminary experimental electric field breakdown data are included to validate simulation results.

Combined Simulation of a Micro Permanent Magnetic Linear Contactless Displacement Sensor

The permanent magnetic linear contactless displacement (PLCD) sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be used for microelectromechanical system (MEMS) measurements is designed and simulated with the CST EM STUDIO® software, including building a virtual model, magnetostatic calculations, low frequency calculations, steady current calculations and thermal calculations. The influence of some important parameters such as air gap dimension, working frequency, coil current and eddy currents etc. is studied in depth.

Extraction of DC busbar parasitics in PWM inverters

PurposeThe purpose of this paper is to present and apply a parasitic extraction approach for the calculation of DC busbar inductances.Design/methodology/approachA computational approach based on the finite integration technique and computed magnetic energy is developed to extract parasitic inductances. The finite integration analysis is conducted via the magnetoquasistatic solver of CST EM Studio® capturing the 3D geometrical effects of the design, as well as the skin and proximity effects.FindingsThe method is applied successfully to evaluate the leakage inductances of two printed circuit boards structures; a backplane sample for the verification purpose and a real DC bus employed in a three‐phase pulse width modulation inverter.Research limitations/implicationsThe paper demonstrates that the method calculates the loop inductances accurately. It does not, however, verify the used technique to split loop inductances into partial inductances.Practical implicationsThe extraction method is easy‐to‐use and able to handle complex geometries within acceptable computation time and accuracy.Originality/valueThe paper introduces a way to compute the parasitic inductances from the results of a numerical electromagnetic field solver.