High-power Electromagnetic Waves Research Articles

Power-modulated reconfigurable nonlinear plasmonic devices without DC power supply and feed circuit

High-power electromagnetic (EM) waves can directly modulate the parameters of nonlinear varactor diodes through the rectification and Kerr effects without relying on external sources. Based on this principle, we propose a power-modulated reconfigurable nonlinear device based on spoof surface plasmon polariton (SSPP) waveguide loaded by varactor diodes, without applying DC power supply or feed circuit. Increasing the input power level reduces the effective capacitance of the varactor diode, leading to a blueshift in the cutoff frequency of the SSPP waveguide. This feature can be employed to realize the switching on/off of the input signal depending on the signal power. On the other hand, the transmission state of a low-power signal can be controlled by inputting another independent high-power EM wave simultaneously. Increasing the power of the control wave will enable the low-power signal within a wider bandwidth switched from off to on states. Experimental results are presented to show the excellent performance of the power-modulated reconfigurable SSPP device. This method can reduce the system complexity and provide inspiration for reconfigurable all-passive multifunctional devices and systems.

Eigenmodes and eigenfunctions of high-power electromagnetic waves in inhomogeneous magnetized plasmas and their stability to stimulated Raman backscattering

Eigenmodes and eigenfunctions of high-power electromagnetic waves in inhomogeneous magnetized plasmas are investigated. Considering the dielectric permittivity in the presence of an external magnetic field and relativistic nonlinearity and considering the inhomogeneity of the electron density in the linear and rippled structures, two nonlinear wave equations are obtained. In the linear regime, eigenmodes and eigenfunctions of the electric field for two-electron densities are obtained. In the nonlinear regime, results indicate that by increasing the external magnetic field, the amplitude of the electric field increases, which affects the dielectric permittivity. The conditions of the stimulated Raman backscattering and the equation of the space-charge potential are obtained. Results also indicate that in the presence of the external magnetic field, plasma inhomogeneity, and relativistic nonlinearity, the stimulated Raman backscattering becomes unstable.

Compact RF transmission unit for nuclear quadrupole resonance spectroscopy

Nuclear quadrupole resonance (NQR) spectroscopy is a non-destructive measurement technique that enables to detect materials of interest very accurately. This technique works by sending high power electromagnetic waves with radio frequency (RF) very specific to the molecular structure to excite the sample and detecting the respond signal with the same frequency. Portable NQR detectors can be potentially developed to detect explosives with non-metallic containers in the fields. However, commercial RF high power amplifiers are large and heavy, so they are not practical for field usage. In this work, we demonstrate a compact NQR transmission part which composed of an active input signal conditioner, a class-D amplifier, and an NQR coil. The active input signal conditioner circuit will convert a single rf pulse with low amplitude (<0.5Vp) to two pulses (with 180° phase difference) and they are subsequently amplified to TTL level. In the class-D amplifier, the pre-amplified pulses are further amplified by a high voltage gate driver IC to 24V amplitude. These high voltage pulses are converted to a single 24V pulse by MOSFETs connected in a half bridge configuration. Finally, the amplified pulse is fed to the NQR coil, i.e., a low impedance LC series resonance circuit. The voltage across the coil at resonance frequency is about 1kVpp.

Characteristic Analysis of Cascading-Combination DC/DC Controlled-Source Circuit for Marine Electromagnetic Transmitter

Nowadays marine electromagnetic method is a geophysical method which can effectively explore natural gas hydrate (NGH) resources. This method acquires seafloor structure and distribution laws of mineral resources by transmitting high-power electromagnetic waves to the seafloor, and its detection depth relies on intensity of transmitted electromagnetic waves. At present, marine electromagnetic transmitter is inappropriate for transmission of high-power electromagnetic waves, and therefore, a novel DC/DC controlled-source circuit formed by input-series and output-parallel ZVZCS DC/DC controlled-source circuit units was proposed in this paper, and thus transformation of high-voltage and high-power electric energy was realized by using switching devices with low rated voltage and rated current. Common duty ratio control is adopted to construct small-signal mathematical model of cascading-combination ZVZCS DC/DC controlled-source circuit, influences of parameters on voltage balance at input side and current balance at output side are analyzed. Simulation and experimental results verify that the proposed circuit has favorable voltage and current sharing effect and could satisfy deep exploration requirements of marine electromagnetic transmitter with high transmission voltage.

Energy Selective Antenna: Concept, Design, and Experiment

In this article, a novel concept of energy selective antenna (ESA) is presented for integrating the functions of the common antenna and the adaptive high-power electromagnetic protection. To demonstrate this concept, a typical structure based on the microstrip patch antenna loaded with limiting PIN diodes is designed. It behaves as a normal antenna under the low-power incidence with the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -status of PIN diodes but rejects the signal in the interested frequency band when the PIN diodes are triggered by the high-power electromagnetic waves. An equivalent circuit is presented to illustrate the operation principle and the parametric studies are carried out to investigate the effects of several key factors on the proposed ESA. Furthermore, a prototype is fabricated and the measured results indicate that the antenna has excellent bandwidth and radiation performance in the normal working state, while performing a good isolation of more than 25 dB in the protection state.

TESLA’S INVENTIONS IN PHYSICS AND HIS ENGINEERING SPIRIT

The article describes Tesla’s inventions in physics. Tesla’s engineering spirit is compared to M. Faraday’s and A. A. Michelson’s spirit of discovery in electromagnetism. Tesla’s unfinished investigative journey, from great experiments in electrical technology and radio technology to the physical theories he derived from them, are examined historically and scientifically. Several discoveries and individual experiments are described that were signifcant in the subsequent development of accelerator technology, as well as Tesla’s monopole antenna for high power and long-range electromagnetic waves, in which the principle of Tesla’s transformer is applied. Within the framework of classical electromagnetic theory, calculations and modern analysis of the system for the study of Tesla’s model of the long-distance wireless transmission of electromagnetic energy or information are presented, demonstrating the scientific basis for Tesla’s ideas. The coverage of Tesla’s inventions and contributions in the physics and electrical engineering curricula at the University of Zagreb is reviewed, especially in textbooks and other works by Ivan Supek, Vatroslav Lopašić and Tomo Bosanac. An interpretation is offered of Tesla’s interest in Goethe’s poetry, which provided an impetus for his inventions and desire for knowledge.

Numerical Evaluation of Human Body Near Field Exposure to a Vehicular Antenna for Military Applications.

BackgroundThe use of electromagnetic (EM) technologies for military applications is gaining increasing interest to satisfy different operational needs, such as improving battlefield communications or jamming counterpart's signals. This is achieved by the use of high-power EM waves in several frequency bands (e.g., HF, VHF, and UHF). When considering military vehicles, several antennas are present in close proximity to the crew personnel, which are thus potentially exposed to high EM fields.MethodsA typical exposure scenario was reproduced numerically to evaluate the EM exposure of the human body in the presence of an HF vehicular antenna (2–30 MHz). The antenna was modeled as a monopole connected to a 3D polygonal structure representing the vehicle. Both the EM field levels in the absence and in the presence of the human body and also the specific absorption rate (SAR) values were calculated. The presence of the operator, partially standing outside the vehicle, was simulated with the virtual human body model Duke (Virtual Population, V.3). Several exposure scenarios were considered. The presence of a protective helmet was modeled as well.ResultsIn the area usually occupied by the personnel, E-field intensity radiated by the antenna can reach values above the limits settled by international safety guidelines. Nevertheless, local SAR values induced inside the human body reached a maximum value of 14 mW/kg, leading to whole-body averaged and 10-g averaged SAR values well below the corresponding limits.ConclusionA complex and realistic near-field exposure scenario of the crew of a military vehicle was simulated. The obtained E-field values radiated in the free space by a HF vehicular antenna may reach values above the safety guidelines reference levels. Such values are not necessarily meaningful for the exposed subject. Indeed, SAR and E-field values induced inside the body remain well below safety limits.

Ultrathin and Mechanically Robust Mussel Byssus‐Inspired MXene@Aramid Nanofibers Materials with Superior Endurance in Harsh Environments for Tunable EMI Shielding Performance

AbstractReducing the fire hazards caused by high power electromagnetic (EM) waves and maintaining operational status of EM interference (EMI) shielding devices in harsh environments have caught increasing eyesight. In this paper, a series of promising EMI shielding materials with mussel byssus‐inspired structure are accomplished via an efficient vacuum‐assisted filtration approach. The flexible multilayered MXene@ANF nacres reveal superior mechanical property compared with both self‐supporting MXene film and MXene@ANF mixture film. Meanwhile, these nacres exhibit both exceeding and tunable EMI shielding effectiveness (EMI SE) of 40–60 dB in 8.2–12.4 GHz with a thickness of ≈20 µm and the absolute SE (SSEt) accomplishes 36641.94 dB·cm2 g−1. Besides, the exceeding thermal insulation of ANF offers the MXene nacres with an outstanding flame‐stopping capacity, and it can still block 99.99% EM waves after 2 min burning. Furthermore, MXene nacres perform superior endurance in harsh environment and retain EMI SE of 42 dB after the ultralow temperature damage. The EMI SE and fire safety of MXene@ANF with two typical structures, composite films and foam, are also systematically investigated. Therefore, this work is promising to fabricate tunable EMI shielding products with low fire hazards and high endurance in harsh environments.

Cell-type continuous electromagnetic radiation system generating millimeter waves for active denial system applications

The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living organisms. It irradiates a biological sample placed in a 30 × 30 × 50 cm3 cell with electromagnetic waves in the 3.15-mm-wavelength region (with an output of ≥1 W) and analyzes the temperature change of the sample. A vacuum electronic device-based coupled-cavity backward-wave oscillator converts the electron energy of the electron beam into radiofrequency (RF) energy and radiates it to the target through an antenna, increasing the temperature through the absorption of RF energy in the skin. The system causes pain and ultimately reduces combat power. A cell-type continuous electromagnetic radiation system consisting of four parts—an electromagnetic-wave generator, a high-voltage power supply, a test cell, and a system controller—generates an RF signal of ≥1 W in a continuous waveform at a 95-GHz center frequency, as well as a chemical solution with a dielectric constant similar to that of the skin of a living organism. An increase of 5 °C lasting approximately 10 s was confirmed through an experiment.

Controlled beat-wave Brillouin scattering in the ionosphere

Stimulated Brillouin scattering experiments in the ionospheric plasma using a single electromagnetic pump wave have previously been observed to generate an electromagnetic sideband wave, emitted by the plasma, together with an ion- acoustic wave. Here we report results of a controlled, pump and probe beat-wave driven Brillouin scattering experiment, in which an ion-acoustic wave generated by the beating of electromagnetic pump and probe waves, results in electromagnetic sideband waves that are recorded on the ground. The experiment used the EISCAT facility in northern Norway, which has several high power electromagnetic wave transmitters and receivers in the radio frequency range. An electromagnetic pump consisting of large amplitude radio waves with ordinary (O) or extraordinary (X) mode polarization was injected into the overhead ionosphere, along with a less powerful probe wave, and radio sideband emissions observed on the ground clearly show stimulated Brillouin emissions at frequencies agreeing with, and changing with, the pump and probe frequencies. The experiment was simulated using a numerical full-scale model which clearly supports the interpretation of the experimental results. Such controlled beat-wave experiments demonstrate a way of remotely investigating the ionospheric plasma parameters.

High Power Electromagnetic Waves Exposure of Healthy and Tumor Bearing Mice: Assessment of Effects on Mice Growth, Behavior, Tumor Growth, and Vessel Permeabilization.

High power radiofrequencies may transiently or permanently disrupt the functioning of electronic devices, but their effect on living systems remains unknown. With the aim to evaluate the safety and biological effects of narrow-band and wide-band high-power electromagnetic (HPEM) waves, we studied their effects upon exposure of healthy and tumor-bearing mice. In field experiments, the exposure to 1.5 GHz narrow-band electromagnetic fields with the incident amplitude peak value level in the range of 40 kV/m and 150 MHz wide-band electric fields with the amplitude peak value in the range of 200 kV/m, did not alter healthy and tumor-bearing animals’ growth, nor it had any impact on cutaneous murine tumors’ growth. While we did not observe any noticeable behavioral changes in mice during the exposure to narrow-band signals when wide-band HPEM signals were applied, mice could behave in a similar way as they respond to loud noise signals: namely, if a mouse was exploring the cage prior to signal application, it returned to companion mates when wide-band HPEM signals were applied. Moreover, the effect of wide-band signals was assessed on normal blood vessels permeability in real-time in dorsal-chamber-bearing mice exposed in a pilot study using wide-band signal applicators. Our pilot study conducted within the applicator and performed at the laboratory scale suggests that the exposure to wide-band signals with the amplitude of 47.5 kV/m does not result in increased vessel permeability.

Dependence of Irradiated High-Power Electromagnetic Waves on the Failure Threshold Time of Semiconductors Using a Closed Waveguide

The failure threshold time of semiconductors caused by the impact of irradiated high-power electromagnetic waves (HPEM) is experimentally studied. A SN7442 integrated circuit (IC) is placed in an emulator with a WR430 closed waveguide and is irradiated by HPEM generated from a magnetron oscillator. The state of the SN7442 component is observed by a light-emitting diode (LED) detector and the voltage measured in the SN7442 component. As the magnitude of the electric field in the HPEM is varied from 24 kV/m to 36 kV/m, the failure threshold time falls from 195 s to 17 s with dependence of the irradiated electric field (E) on the failure threshold time (T) from T~E−12 to a T~E−6.

A Study on How to Overcome Crisis Management against Drone Threat

During the Fourth Revolution, the unmanned aerial vehicle sector is used not only for commercial transportation but also for reconnaissance and attack on battlefield areas in the military, and the development of unmanned aerial vehicles is emerging as a new type of threat. Through a comparative analysis of current and new response weapons, the effectiveness and cost of the response weapon system, management factors, and combatant minimization were analyzed. The development of a new concept response weapon system requires the establishment of a more efficient air defense system, and the development and necessity of laser weapons, a new concept response weapon suitable for the fourth revolution, were studied. By converting current military aircraft into oriented energy laser weapons among non-lethal weapons such as high-power microwave, high-power electromagnetic waves, and high-energy weapon systems, the development of various types of laser weapon systems will be able to develop for each army, navy, and air force.

Analysis of Electromagnetic Pulse Effects Under High-Power Microwave Sources

High-power microwave sources applied to a directed-energy weapon can lead to permanent damage by radiating concentrated energy in a specific direction to disturb or overload electronic equipment. The effect analysis on the target, such as electronics exposed to electromagnetic pulse, should be considered as an important factor in determining the performance of high-power microwave sources and conducting experimental evaluations. In this study, a magnetically insulated transmission line oscillator, one of the representative high-power microwave sources based on vacuum electronics device, was constructed and experimental analysis with respect to electromagnetic pulse effects was performed. The specification of the magnetically insulated transmission line oscillator used in this study corresponded to 3 GW of high-power electromagnetic wave pulses operating at L-band. The power efficiency was approximately 10 – 15%. For effective targeting, a Vlasov antenna that converts TM01 mode to TE11 mode was designed and fabricated. The radiation pattern was confirmed via fluorescent lamps, and to confirm the effect of the directed-energy weapon on the target, an effect analysis was performed using a portable electronic device as a sample. Furthermore, the electric field was measured with a D-dot probe and quantified and compared. This study presents a future blueprint of the value of the directed-energy weapon by predicting the radiant output power of the weapon in the far-field region after it is mounted on a movable ground vehicle or unmanned aerial vehicle.

Evaluations of Acute and Sub-Acute Biological Effects of Narrowband and Moderate-Band High Power Electromagnetic Waves on Cellular Spheroids

High power electromagnetic signals can disrupt the functioning of electronic devices. As electromagnetism plays a role in cells homeostasis, such electromagnetic signals could potentially also alter some physiological processes. Herein we report on distinct biological parameters assessment after cellular spheroids exposure to high power electromagnetic signals, such as the ones used for defense applications. Signals effects were assessed in tumor cells spheroids and in normal human dermal fibroblasts spheroids, where macroscopic aspect, growth, plasma membrane integrity, induction of apoptosis, ATP content, and mitochondrial potential were investigated after spheroids exposure to high power electromagnetic signals. No significant effects were observed, indicating that 1.5 GHz narrowband electromagnetic fields with incident amplitude level of 40 kV/m, and 150 MHz moderate-band electric fields with an amplitude of 72.5 to approximately 200 kV/m, do not cause any significant alterations of assessed parameters.

Three-Level DC-DC Controlled-Source Circuit of Marine Electromagnetic Detection Transmitter

Nowadays, marine electromagnetic method is a geophysical method which can effectively explore natural gas hydrate (NGH) resources. This method acquires seafloor structure and distribution laws of mineral resources by transmitting high-power electromagnetic waves to the seafloor, and its detection depth relies on the intensity of transmitted electromagnetic waves. At present, marine electromagnetic transmitter is not proper for transmission of high-power electromagnetic waves, and therefore, a novel controlled-source circuit of soft switching three-level marine electromagnetic transmitter is proposed in this paper, one step-down winding is added at the secondary side of high-frequency transformer in series connection with a linear inductor, asymmetric phase-shift PWM control is used, and soft switching of controlled-source circuit within the overall power range is realized. A detailed analysis of the operation process and circuit characteristics is given, and finally, a prototype is designed. Experimental results indicate that this circuit is of wide ZVS range and high efficiency, and it meets requirements for deep-sea detection of high-voltage power supply transmitter.

Electromagnetic Compatibility in Electron Cyclotron Resonance Heating System

The electron cyclotron resonance heating (ECRH) is a very important plasma heating method in experimental advanced superconducting tokamak (EAST). There are four gyrotrons in the EAST ECRH system that can generate 4-MW/100-s/0.14-THz wave. The ECRH system is a complex terahertz system that involves ultralow temperature, ultrahigh vacuum, strong magnetic field, high-power electromagnetic wave, and weak diagnostic signal. There are many electromagnetic compatibility problems in the ECRH system. This is the first report about the electromagnetic compatibility for the ECRH system. In the operation of the ECRH system, many electromagnetic compatibility problems have been found and resolved. We can suppress the interference and improve the accuracy of power monitoring and the effectiveness of radio frequency protection by using the magnetic rings. The influence of the magnetic field on the current transformers was analyzed. Some electromagnetic compatibility issues in the data acquisition system were discussed. After solving the electromagnetic compatibility problems, the EAST ECRH system can stably output high-power terahertz wave.

Experiments Designed to Study the Non-Linear Transition of High-Power Microwaves through Plasmas and Gases

The interaction of powerful sub-picosecond timescale lasers with neutral gas and plasmas has stimulated enormous interest because of the potential to accelerate particles to extremely large energies by the intense wakefields formed and without being limited by high accelerating gradients as in conventional accelerator cells. The interaction of extremely high-power electromagnetic waves with plasmas is though, of general interest and also to plasma heating and wake-field formation. The study of this subject has become more accessible with the availability of sub-nanosecond timescale GigaWatt (GW) power scale microwave sources. The interaction of such high-power microwaves (HPM) with under-dense plasmas is a scale down of the picosecond laser—dense plasma interaction situation. We present a review of a unique experiment in which such interactions are being studied, some of our results so far including results of our numerical modeling. Such experiments have not been performed before, self-channeling of HPM through gas and plasma and extremely fast plasma electron heating to keV energies have already been observed, wakefields resulting from the transition of HPM through plasma are next and more is expected to be revealed.

Development of a High-Power Burst Pulse Generator Based on the Sequential Operation of Magnetic Switches

Nanosecond and subnanosecond high-voltage pulses have used in new biological applications, such as cancer treatment using an ultrashort pulsed high electric field. For this treatment, the use of high-power pulsed electromagnetic wave has been proposed to obtain the required high electric field. This paper focuses on the design of a compact high-power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for cancer treatment. We developed a pulsed power generator that continuously outputs multiple pulses via a nonlinear transmission line (NLTL) using magnetic switches. The NLTL comprises a ladder of capacitors and saturable inductors. The NLTL generates a pulse train by delaying the propagation of the pulse using the magnetic switch of each ladder. The frequency of repetition of the burst pulse is 13.8 MHz. The peak output voltage is 7 kV at the maximum input voltage of 28 kV. The number of pulses in the pulse train can be varied by the number of units of the magnetic switch.

진공 내 상대론적인 영역의 전자빔을 이용한 플라즈마 항적장 가속기 기반 체렌코프 방사를 통한 결맞는 고출력 전자파 발생 기술 연구

진공 내 상대론적인 영역의 전자빔을 이용한 플라즈마 항적장 가속기 기반 체렌코프 방사를 통한 결맞는 고출력 전자파 발생 기술 연구