Three‐dimensional electromagnetic analysis of a vacuum window involving waveguides

Electromagnetic Environment Associated with Lightning Strikes to Tall Strike Objects

We study the motion states of charged particles in a homogeneous electromagnetic field based on the Maxwell equations. The authors propose the charged particle properties analysis based on the Maxwell equation and electromagnetic field, first explain the Maxwell equation and electromagnetic field properties analysis, and then analyze the charged particles in the composite field (electric and magnetic field coexistence). List the important knowledge points about the motion of charged particles in an electric field, and determine the center of the circle where the charged particles move in a circular motion, simulate the motion of charged particles in a uniform orthogonal electromagnetic field, if at, the trajectory of the charged particle is a short-amplitude cycloid, if, the trajectory of the charged particle is a long cycloid, if. The realization of simulation is mainly based on theory to obtain phenomena, although it has extensive practical significance for confirmatory experiments, when inspiring and guiding students to carry out inquiry learning, physics teachers should still organically combine simulation experiments with traditional experimental teaching, teacher explanations, and student experiments in teaching design and teaching implementation, in order to cultivate students' independent inquiry ability and experimental innovation ability.

Many devices contain parts that undergo motion due to electromagnetic forces. The motion causes the electromagnetic fields to change. Thus the electromagnetic fields must be computed along with the structural motion. In many cases the motion produced by electromagnetic forces is desired motion. However, in many devices, some undesired motion can occur due to electromagnetic forces. The motion creates motion-induced eddy currents which in turn affect the electromagnetic fields and forces. A finite element technique is described that fully couples structural and electromagnetic analysis in the time domain. The code is applied to a superconducting dipole model in order to study deformations and stresses during ramp and quench. The results of this coupled analysis enables the designer to visualize deformations, vibrations, displacements and all electromagnetic field quantities of the device and to try different solutions to enhance its performance.

Hydrogenic species transport model for ceramic alumina used in ITER ICRH H&CD & Diagnostics Systems

Magnetic field therapy is an established technique in the treatment of pseudarthrosis. In cases of osteomylitis, palliation is also observed. This study focuses on the impact of different electric and electromagnetic fields on the growth of Staphylococcus aureus by in vitro technologies. Cultures of Staphylococcus aureus in fluid and gel-like medium were exposed to a low-frequency electromagnetic field, an electromagnetic field combined with an additional electric field, a sinusoidal electric field and a static electric field. In gel-like medium no significant difference between colony-forming units of exposed samples and non-exposed references was detected. In contrast, Staphylococcus aureus concentrations in fluid medium could clearly be reduced under the influence of the four different applied fields within 24 h of experiment. The strongest effects were observed for the direct current electric field which could decrease CFU/ml of 37%, and the low-frequency electromagnetic field with additional induced electric alternating field with a decrease of Staphylococci concentration by 36%. The effects of the electromagnetic treatment on Staphylococci within fluid medium are significantly higher than in gel-like medium. The application of low-frequency electromagnetic fields corroborates clinical situations of bone infections during magnetic field therapy.

The anisotropic perfectly matched layer (PML) is employed in the mode-matching analysis of an open-ended rectangular waveguide radiating into a layered half space. In the analysis, the layered half space is approximated by a large rectangular waveguide coated with anisotropic PMLs along its walls. Closed form expressions of the eigenvalues and the electromagnetic fields for both TE and TM modes in the anisotropic PML-filled rectangular waveguide are first derived and then used in the mode-matching analysis of the resultant waveguide-junction problem. Numerical results for the aperture admittance and reflection coefficient are presented and compared with available data in the literature. Good agreement is achieved.

A previous paper described the design of a vacuum window proposed for use in the WR-1800 waveguide. This work details the results of a high power test of the completed prototype window. The window passed all design goals when operated in a short-circuited load. For the case of a matched load, the travelling wave power reached a maximum of 260 kW CW with vacuum bursts as a limiting factor. In addition to the results from the high power tests, some results from low power tests using a network analyzer are given. Some general conclusions are drawn concerning the design of vacuum windows in a rectangular waveguide. >

The construction of multi-component composites has become an attractive strategy for high-performance microwave absorption through balancing the magnetic and dielectric loss. However, the influences of different components on absorption performance are ambiguous, which has inevitably hampered the widespread applications of microwave absorbents. Herein, we rationally designed the multi-component absorbers of N-doped carbon composited with Fe/Fe3C nanoparticles, and systematically investigated the impacts of Fe/Fe3C nanoparticles and Fe-Nx moieties on the microwave-absorbing capacities. It is found that the coexisitence of Fe/Fe3C and Fe-Nx is indispensable to realize the strong microwave absorption ability by simultaneously enhancing the dielectric and magnetic loss in the frequency range of 2–18 GHz. As expected, our optimal absorber dispersed in paraffin with a filler loading of 15 wt% exhibits the minimum reflection loss (RLmin) value of −49 dB and the maximum effective absorption bandwidth (BWeff) value of 4.2 GHz at a low thickness. Our work specifies the importance and influence of the coexistence between the Fe-Nx configurations and Fe/Fe3C nanoparticles in the carbon-based composites for the superior microwave absorption and inspires the future fabrication of extraordinary materials in the electromagnetic field.

For an effective additional heating system in the experimental tokamak-type system the pillbox-type vacuum window is proposed to isolate each part. L.J.B. Bergeron's formulation (1941) of the pillbox-type vacuum window connected to cylindrical waveguides is described, and the fundamental characteristics of the electromagnetic field within this system are shown. Local heating at the surface of the dielectric disk may be decreased by reducing circumferential dependence by using cylindrical waveguides. A unified analysis involving the pillbox window and both the input-side waveguide and the output-side one has been performed using the presented method. The results obtained present the complex variations of the distribution of the field in the overall analyzed region as a function of the length of the pillbox window. These results illustrate the characteristics of the three-dimensional analysis. The analyzed model is described; in particular, the boundary conditions of the conductor are explained. The numerical results of the field distributions are shown by the longitudinal magnetic field variations and the electric field variations in the various cross sections in the pillbox window.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In this study, we propose a two-step approach to evaluate electromagnetic interference (EMI) with a wearable electrocardiogram (ECG) sensor. The two-step approach combines a quasi-static electromagnetic (EM) field analysis and an electric circuit analysis, and is applied to the EMI analysis at frequencies below 1 MHz for our developed wearable ECG to demonstrate its usefulness. The quasi-static EM field analysis gives the common mode voltage coupled from the incident EM field at the ECG sensing electrodes, and the electric circuit analysis quantifies a differential mode voltage at the differential amplifier output of the ECG detection circuit. The differential mode voltage has been shown to come from a conversion from the common mode voltage due to an unbalance between the contact impedances of the two sensing electrodes. It may achieve nearly 0.6 V at the differential amplifier output under 10-V/m plane-wave incident electric field, and completely mask the ECG signal. It is essential to reduce the unbalance as much as possible to not cause a significant interference voltage in the amplified ECG signal.

The mechanisms whereby electromagnetic (EM) fields stimulate changes in biosynthesis in cells are not known. It has has generally been assumed that EM fields first interact with cell membranes, but this pathway may not be only one. Interactions with membranes are well documented, but recent studies of EM signal transduction in the membrane Na,K-ATPase are best explained by direct interaction of electric and magnetic fields with mobile charges within the enzyme. Interaction with moving charges may be a mechanism that is operative in other biopolymers. Recent studies on DNA have shown that large electron flows are possible within the stacked base pairs of the double helix. Therefore, gene activation by magnetic fields could be due to direct interaction with moving electrons within DNA. Electric fields as well as magnetic fields stimulate transcription, and both fields could interact with DNA directly. The mechanism of EM field-stimulated transcription may be related to the process in striated muscles, where endogenous electrical activity induces the synthesis of new proteins.

The role of blocking dynamics and current on wave scattering due to finite floating elastic plate

Gyrotron has proven to be an efficient source for RF generation at high power and high frequency level. Gyrotron has very significant and specific role to play, particularly, in plasma, material, spectroscopy and energy research. The chapter covers the selection of dielectric materials and power handling capability of RF windows. The design analysis of RF window with window disk thickness and diameter are optimized considering the minimum return loss and the minimum insertion loss by using CST microwave studio. The advantage of the double disc window cooling is most effective. In the 42 GHz window design, double disc winnow are using and the temperature on the disc of RF window does not exceed 100 degree C and found in safe limit. The design of RF window depends on the dielectric characteristics like dielectric constant, loss tangent, permittivity, etc., of the window materials. The dielectric permittivity and loss tangent of window material affect the absorption and transmission of RF power. The thermal analyses are performed by using finite element analysis code ANSYS code on the basis of electrical design of RF window.

Electromagnetic field propagation inside composite materials represents a challenge where fiber-scale simulation remains intractable using classical simulation methods. The present work proposes an original 3D simulation with a mesh resolution fine enough to resolve the fiber scale, thanks to the use of Proper Generalized Decomposition (PGD)-based space decomposition, which avoids the necessity of considering homogenized properties and considers the richest description of the involved physics from the solution of the Maxwell equations. This high-resolution simulation enables comparing the electromagnetic field propagation in a composite part, depending on the considered frequency and the fiber’s/wave polarization’s relative orientation. The electromagnetic fields are then post-processed to identify the heat generation terms and- the resulting induced thermal field. The results prove the ability of the PGD-based discretization to attain extremely high levels of resolution, the equivalent of 1010 finite-element degrees of freedom. The obtained results show an enhanced wave penetration when the electric field polarization coincides with the fiber orientation. On the contrary, when the electric field is polarized along the normal to the fiber orientation, both the penetration and the associated heating reduce significantly, compromising the use of homogenized models, rendering them unable to reproduce the observed behaviors.

&lt;p class="1Body"&gt;Experiments show that, there is the electrostatic field around the permanent magnet; since the electromagnetics can not explain this phenomenon, it can be concluded that there are some defects in electromagnetics. This paper makes an analysis of the defects of electromagnetics from fourteen aspects. It is noted that, the basic defect of electromagnetics is that there is no explanation of any inherent causes and physical processes of electromagnetic induction, displacement current, Lorentz force and other surface phenomena. Moreover, it may also lead us to make incorrect inferences in the theoretical analysis of electromagnetics, e.g. the same direction of action and reaction, infinitely high kinematic velocity of magnetic field, etc. It can be seen from analysis of all electromagnetic phenomena that, all the electromagnetic phenomena will be inevitably accompanied by an electron motion; and the electron motion is bound to take effect through an electric field; therefore, the analysis of motion in an electric field is the basis for analysis of all electromagnetic phenomena. This paper proposes seven rules for analysis of motion in an electric field, analyzes the uniform motion and variable motion in an electric field on the basis of such rules, clarifies the inherent causes of Lorentz force, theoretically qualitatively and quantitatively demonstrates why there exists the electrostatic field at some locations around the permanent magnet, and considers that all the magnetic phenomena are resulted from the contraction of electric field in the direction of motion, which is derived from the natural law of constant velocity of light, and therefore all the electromagnetic phenomena is rooted in the constant velocity of light. Through the analysis of variable motion in an electric field, this paper proves the law of displacement current and electromagnetic induction, clarifies the physical processes of such phenomena, deduces the law of total current, explains why electric field strength and magnetic field strength of electromagnetic wave must be in same phase and why a plane wave has the electric and magnetic fields only with a certain length but no source, and considers that neither fast nor slow propagation velocity of electromagnetic wave is good and that the actual velocity of light is the ideal velocity of light.&lt;/p&gt;