High-power Electromagnetic Radiation Research Articles

Thermal management by manipulating electromagnetic parameters

Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it. However, in a high-power electromagnetic radiation environment, the temperature of the absorbing material rises significantly and even burns. It becomes critical to ensure electromagnetic absorption performance while minimizing temperature rise. Here, we systematically study the coupling mechanism between the electromagnetic field and the temperature field when the absorbing material is irradiated by electromagnetic waves. We find out the influence of the constitutive parameters of the absorbing materials (including uniform and non-uniform) on the temperature distribution. Finally, through a smart design, we achieve better absorption and lower temperature simultaneously. The accuracy of the model is affirmed as simulation results aligned with theoretical analysis. This work provides a new avenue to control the temperature distribution of absorbing materials.

Damage study of UAV cluster by high-power electromagnetic radiation

With regard to the threat of Unmanned Aerial Vehicle(UAV) clusters, the mechanism and rule of the damage to UAV cluster caused by electromagnetic wave is explored in this paper. A typical satellite navigation antenna high power electromagnetic radiation is studied with the experimental and simulation, in which, the damage sensitive parts and threshold of damage is obtained, which provides support for interference and damage UAV cluster of enemy and protection research for UAV of our own.

Hyperparametric Oscillation via Bound States in the Continuum.

Optical hyperparametric oscillation based on the third-order nonlinearity is one of the most significant mechanisms to generate coherent electromagnetic radiation and produce quantum states of light. Advances in dispersion-engineered high-Q microresonators allow for generating signal waves far from the pump and decrease the oscillation power threshold to submilliwatt levels. However, the pump-to-signal conversion efficiency and absolute signal power are low, fundamentally limited by parasitic mode competition and attainable cavity intrinsic Q to coupling Q ratio, i.e., Q_{i}/Q_{c}. Here, we use Friedrich-Wintgen bound states in the continuum (BICs) to overcome the physical challenges in an integrated microresonator-waveguide system. As a result, on-chip coherent hyperparametric oscillation is generated in BICs with unprecedented conversion efficiency and absolute signal power. This work not only opens a path to generate high-power and efficient continuous-wave electromagnetic radiation in Kerr nonlinear media but also enhances the understanding of a microresonator-waveguide system-an elementary unit of modern photonics.

Decomposition of carbon dioxide in a discharge maintained by continuous focused sub-terahetz radiation at atmospheric pressure

For the first time, experiments were carried out on the decomposition of carbon dioxide in a plasma torch maintained by continuous focused gyrotron radiation with a frequency of 263 GHz in an argon flow at atmospheric pressure. It is shown that, despite the decrease in the electron density by a factor of 5, when 3% carbon dioxide is added to the plasma-forming gas, it is possible to achieve its degree of conversion of 22% due to the nonequilibrium nature of maintaining the discharge. Thus, the prospects of using high-power electromagnetic radiation in the sub-terahertz range for solving plasma-chemical problems of the decomposition of highly stable molecules have been demonstrated. Keywords: microwave discharge, nonequilibrium plasma, gyrotron, subterahertz radiation, CO2 decomposition. Keywords: microwave discharge, nonequilibrium plasma, gyrotron, subterahertz radiation, CO2 decomposition.

Разложение углекислого газа в разряде, поддерживаемом непрерывным сфокусированным субтерагецевым излучением при атмосферном давлении

For the first time, experiments were carried out on the decomposition of carbon dioxide in a plasma torch maintained by continuous focused gyrotron radiation with a frequency of 263 GHz in an argon flow at atmospheric pressure. It is shown that, despite the decrease in the electron density by a factor of 5, when 3% carbon dioxide is added to the plasma-forming gas, it is possible to achieve its degree of conversion of 22% due to the nonequilibrium nature of maintaining the discharge. Thus, the prospects of using high-power electromagnetic radiation in the sub-terahertz range for solving plasma-chemical problems of the decomposition of highly stable molecules have been demonstrated. Keywords: microwave discharge, nonequilibrium plasma, gyrotron, subterahertz radiation, CO2 decomposition.

The application of small size spiral tube coil antenna in the development of electromagnetic radiator

When the electromagnetic wave propagates in water, the attenuation will increase with the increase of frequency, so the application of electromagnetic wave in water is limited to the low frequency band. At present, in order to realize the low-frequency electromagnetic wave radiation, the commonly used method is tuning the spiral tube coil antenna (Electromagnetic radiator). In practical application, the electromagnetic radiator used to realize high-power electromagnetic radiation usually has the characteristics of large size and many coil turns. Therefore, for the development of high-power electromagnetic radiator, there are many difficulties, such as high cost and difficult manufacture. Therefore, it is necessary to analyse the relationship between the radiation performances of different sizes of electromagnetic radiator, and use this relationship to guide the development of high-power electromagnetic radiator. Based on this, this paper analysed the radiation characteristics of spiral tube coil antenna, and the application of small-size electromagnetic radiator in the development of electromagnetic radiator.

Эффект трансформации электрического поля в анизотропных диэлектрических средах

The authors consider the aspects of the electric field distribution in an anisotropic medium and establish how its longitudinal and transverse components depend on the geometric factors. A rectangular plate of dimensions a×b×c is studied, its selected crystallographic axes located in the plane of the side face (a×b), while one of the axes is oriented at a certain angle α to the edge a. It is shown that applying a certain potential difference to the upper and lower faces electrically polarizes the volume of the plate and causes the appearance of the longitudinal and transverse components of the internal electric field. The authors investigate the possibility of transforming the magnitude of the electric field and methods for its optimization. The transformation coefficient of such a device is determined by the anisotropy of the dielectric permeability of the plate material and its shape coefficient k = a/b. The paper considers one of the design options for an anisotropic dielectric transformer and proposes its equivalent electrical circuit. Structural elements based on anisotropic dielectric transformers may be widely used both in power supplies of various electronic devices and for coordination of radar transceiver systems with antenna arrays of centimeter, millimeter and submillimeter wavelength ranges. The possibility of simultaneous transformation of constant and alternating electric fields allows them to be used in devices of simultaneous comparison, enabling to determine the current values of voltage, as well as the power of electromagnetic radiation in a wide range of wavelengths. The vortex nature of the electric field in the plate’s volume caused by the coefficient anisotropy of the dielectric permeability also creates the preconditions for the emergence of new principles for generating high-power electromagnetic radiation in a wide spectral range. The generation frequency of such devices is determined by the geometric dimensions of the anisotropic plate. The use of the described transformation effect will significantly expand the possibilities of practical application of the considered electrostatic phenomena, which will lead to the emergence of a new generation of devices for microwave technology, electronics and electric power.

Theoretical Study of a ${W}$ -Band-Covering Frequency-Tunable Gyrotron

The gyrotron has already demonstrated the capability of generating high-power coherent electromagnetic (EM) radiation at high frequencies and finds application in fusion plasma heating and magnetic resonance spectroscopy. In this article, we propose a ${W}$ -band gyrotron, which uses a so-called multimode switching scheme to realize ultrabroadband frequency tuning capability, nearly covering about 70% of the ${W}$ -band (75–110 GHz) range. The tuning strategy used to suppress mode competition and stabilize gun parameters in such an open-cavity multimode switching gyrotron is presented. Theoretical study shows that the multimode switching gyrotron can generate a frequency tuning range much wider than a conventional step-tuning gyrotron or a single-mode tuning gyrotron. In addition, another technology that uses a slot-assisted circuit to select only axis-symmetrical TE operating modes is presented. Using such a circuit, a tuning range of about 25 GHz in the ${W}$ -band is obtainable. The proposed multimode switching gyrotron is a promising ultrabroadband source for millimeter-wave and terahertz-wave applications.

High-efficiency virtual cathode oscillator with photonic crystal

We study the properties of microwave generation in a virtual cathode oscillator with a photonic crystal composed of metal grids. Our simulation results show the high efficiency of photonic crystal structure utilization in comparison with the standard scheme of an axial virtual cathode oscillator: operation efficiency reaches 20% at the optimal parameters. The obtained results demonstrate that the virtual cathode oscillator with a photonic crystal can be considered as a prospective high-power microwave source where the vircator operation mechanism and photonic crystal properties complement each other to produce high-power electromagnetic radiation.

On the Possibility of Creating a Point-Like Neutron Source

We consider the possibility of creating a compact high-power neutron generator with a small emitting area (of the order of 100 μm) and a neutron yield of 1010s−1 on the basis of a deuterium–deuterium fusion reaction (or 1012 s−1 on the basis of a deuterium–tritium fusion reaction). The fusion takes place under bombardment of a deuterium- (or tritium-) saturated target by a high-current (about 100 mA) focused deuterium ion beam with an energy of ~ 100 keV. The ion beam with total current at a level of hundreds of milliamperes and small emittance (less than 0.1 π·mm·mrad), which is crucial for sharp focusing, can be generated by a quasi-gas-dynamic ion source of a new generation created on the basis of a discharge in an open magnetic trap sustained by high-power electromagnetic radiation of the millimeter wavelength range under electron cyclotron resonance conditions. Simulations of the focusing system for the experimentally obtained ion beam show the possibility to create a deuterium ion beam with a transverse size of 200 μm on the neutron-forming target. Prospects for using such a neutron source for neutron tomography are discussed.

PLASMA TECHNOLOGIES FOR THE PROTECTION OF RADIO ELECTRONIC MEANS FROM EXPOSURE TO HIGH–POWER ELECTROMAGNETIC RADIATIONS WITH ULTRASHORT PULSE DURATION

The urgency of the improvement of methods and means of protection of radio electronic means (REM) due to the development and application of high–power electromagnetic radiation (EMR) generators with ultrashort pulses duration (UPD) is substantiated. It is pointed out that it is possible to solve the problem of REM protection by the complex application of plasma technologies using gaseous and modified solid–state media. By analyzing the known achievements in the field of developing effective methods and creating protection facilities for REM, a number of unresolved problems in the field of creation of plasma protection technologies have been determined. The technique of solving the formulated problems is presented and the main relations are obtained to determine the expediency of using the proposed technology in the interests of the REM integrated protection from the powerful EMR UPD. A relation is made for the breakdown criterion in a gaseous plasma medium that relates the value of the breakdown field to the concentration of charged particles determined by the ionization source. The structure of a solid–state plasma medium is described, which can be used as a protective shield. The order of finding the REM screening coefficient is shown, based on the determination of the distribution function of charged particles for finding the main macroscopic properties of plasma by solving the kinetic equation of the Lenard–Balescu equation. A relation is given for the damping coefficient of an electromagnetic wave in solid–state plasma. Numerical estimates are presented in the form of graphs showing the possibility of using plasma technology to protect the REM from a powerful EMR through possible channels of penetration. The discussion of the obtained results is presented and it is indicated on the possibility and prospects of using the proposed technology for REM protection, especially with limitations on the weight dimensions of protection devices

Generation of high-field narrowband terahertz radiation by counterpropagating plasma wakefields

It is found that nonlinear interaction of plasma wakefields driven by counterpropagating laser or particle beams can efficiently generate high-power electromagnetic radiation at the second harmonic of the plasma frequency. Using a simple analytical theory and particle-in-cell simulations, we show that this phenomenon can be attractive for producing high-field (∼10 MV/cm) tunable terahertz radiation with a narrow line width. For laser drivers produced by existing petawatt-class systems, this nonlinear process opens the way to the generation of gigawatt, multi-millijoule terahertz pulses which are not presently available for any other generating schemes.

Effects on electronics exposed to high-power microwaves on the basis of a relativistic backward-wave oscillator operating on the X-band

An analysis of the effects of electromagnetic pulses from a high-power microwave (HPM) radiation technique is conducted using a relativistic backward-wave oscillator (RBWO) which uses relativistic electron beams in vacuum circuits. The application described here is based on a relativistic electron device and uses relativistic electron beams to generate high-power electromagnetic radiation. The RBWO was fabricated to operate in a relativistic region with a gamma factor (γ) of 2 at an acceleration voltage of 500 kV. A mode-converted relativistic back-wave oscillator with an antenna that converts TM01 to TE11 was designed and fabricated because the electric field of the center in the RBWO circuit is null. The effects on electronic devices by HPM radiation and exposure were assessed. The effects on electronic devices exposed to HPMs, the failure of information equipment, and modulation of and interference with the received signal through a theoretical model of the threshold power relative to the influence on the target were confirmed in a high-output microwave exposure environment. Particularly, information devices containing semiconductors can undergo serious failures and breakdowns due to the thermal secondary breakdown caused by the high-output transient electromagnetic waves, and it is a theoretical consideration that reverse voltage occurs due to the generation of surge current when caught in the PN-junction region. Finally, the range of power regarding the effectiveness of the electromagnetic coupling of electronics exposed to HPM radiation was estimated.

Remote detection of radioactive material using high-power pulsed electromagnetic radiation

Remote detection of radioactive materials is impossible when the measurement location is far from the radioactive source such that the leakage of high-energy photons or electrons from the source cannot be measured. Current technologies are less effective in this respect because they only allow the detection at distances to which the high-energy photons or electrons can reach the detector. Here we demonstrate an experimental method for remote detection of radioactive materials by inducing plasma breakdown with the high-power pulsed electromagnetic waves. Measurements of the plasma formation time and its dispersion lead to enhanced detection sensitivity compared to the theoretically predicted one based only on the plasma on and off phenomena. We show that lower power of the incident electromagnetic wave is sufficient for plasma breakdown in atmospheric-pressure air and the elimination of the statistical distribution is possible in the presence of radioactive material.

Generation of high-power electromagnetic radiation by a beam-driven plasma antenna

In this paper we study how efficiently electromagnetic radiation can be generated by a relativistic electron beam with a gigawatt power level during its injection into a thin magnetized plasma. It is shown that, if the transverse beam and plasma size is compared with the radiation wavelength and the plasma density is modulated along the magnetic field, such a beam–plasma system can radiate electromagnetic waves via the antenna mechanism. We propose a theoretical model describing generation of electromagnetic waves by this plasma antenna and calculate its main radiation characteristics. In the two-dimensional case theoretical predictions on the radiation efficiency are shown to be confirmed by the results of particle-in-cell simulations, and the three-dimensional variant of this theory is used to estimate the peak power of sub-terahertz radiation that can be achieved in beam–plasma experiments in mirror traps.

Pulse-Periodic Regime of Kinetic Instability of the ECR Discharge Plasma Under the Conditions of Double Plasma Resonance

UDC 533.9.01 We study the stability of a dense nonequilibrium plasma of the electron cyclotron resonance (ECR) discharge in an open magnetic trap immediately after the end of heating. The observed instability is accompanied by pulse-periodic generation of high-power electromagnetic radiation at a frequency that is close to the frequency of the upper hybrid resonance and the double gyrofrequency of electrons and by synchronous precipitations of fast electrons from the trap. It is shown that the observed instability is connected with excitation of plasma waves under the conditions of double plasma resonance in the decaying plasma of the ECR discharge.

Traveling-Wave Tube Harmonic Amplifier in Terahertz and Experimental Demonstration

In this paper, a novel traveling-wave tube (TWT) harmonic terahertz (THz) amplifier is proposed for a high-power, wideband, and practical electromagnetic vacuum radiation source. The amplifier is based on the reuse of harmonic information in the spent beam of a normal TWT by harmonic generation, selection, amplification, and coupling. In order to verify this concept, a W-band folded waveguide pulsed TWT with a second-harmonic extraction system in Cascade has been developed for a G-band (170-260 GHz) TWT second-harmonic amplifier. Simulation results from CST Particle Studio show that the amplifier exhibits a good performance. Then, a prototype of the amplifier was fabricated and tested. The experimental results show that over 100-mW second-harmonic output power at most frequencies of the 11.4 GHz of bandwidth at 1% duty cycle was achieved, and the maximum second-harmonic output power reached 500 mW. This paper demonstrates the feasibility that TWT harmonic amplifiers can be used as a potential THz vacuum radiation source, and further progress in development of such novel THz devices is anticipated.

Research on the 650GHz Folded Waveguide BWO

The terahertz (THz) spectrum technique has become an important research content of electromagnetic field in recent years. Folded waveguide backward wave oscillator (BWO) is suitable to be used as THz high-power electromagnetic radiation source. Because it can realize electronic tuning within a wide frequency band and doesn’t require pre-stage source amplifier. In this paper, the high frequency characteristic, the transmission characteristics, and the particle beam wave interaction characteristics of the structure of folded waveguide BWO have been analyzed, and it is utilized to design geometry parameters of 650GHz folded waveguide slow-wave-structure (SWS). The design is been validated by particle beam wave interaction simulation experiments. The experiment results show that the output is over 1.7W within 42GHz bandwidth, and the electron efficiency can exceed 1%.

Prediction and measurement of the electromagnetic environment of high-power medium-wave and short-wave broadcast antennas in far field

With the increasing city size, high-power electromagnetic radiation devices such as high-power medium-wave (MW) and short-wave (SW) antennas have been inevitably getting closer and closer to buildings, which resulted in the pollution of indoor electromagnetic radiation becoming worsened. To avoid such radiation exceeding the exposure limits by national standards, it is necessary to predict and survey the electromagnetic radiation by MW and SW antennas before constructing the buildings. In this paper, a modified prediction method for the far-field electromagnetic radiation is proposed and successfully applied to predict the electromagnetic environment of an area close to a group of typical high-power MW and SW wave antennas. Different from currently used simplified prediction method defined in the Radiation Protection Management Guidelines (H J/T 10. 3-1996), the new method in this article makes use of more information such as antennas' patterns to predict the electromagnetic environment. Therefore, it improves the prediction accuracy significantly by the new feature of resolution at different directions. At the end of this article, a comparison between the prediction data and the measured results is given to demonstrate the effectiveness of the proposed new method.

电磁耦合实验平台系统线缆束的电磁拓扑分析

The analysis of electromagnetic coupling of complex cable bundle system is becoming more difficult with the increasing complexity of the electromagnetic environment. The development of high power electromagnetic radiation technology brings serious electromagnetic threat to those which have complex cable bundle systems and electronic equipment systems. Related to the electromagnetic attacks and electromagnetic protection, there is an urgent need in the aspect of analysis of electromagnetic coupling of complex cable bundle system. Due to the complex geometrical space boundary conditions of complex cable bundle system, it is hard to solve this problem using methods such as the finite difference time domain method(FDTD) and the finite difference frequency domain method(FDFD). Based on the transmission line theory, we use the decomposition skill according to the topology structure to build up a topological model of electromagnetic coupling of complex cable bundle system, and we obtain a method to calculate the terminal voltage and current of the system. We present some simulation examples to verify the availability of electromagnetic topology method in dealing with the electromagnetic coupling effect of cable network.