High-power Electromagnetic Pulses Research Articles

Tightly coupled arrays with time-domain beam scan for the radiation of high-power ultrawideband electromagnetic pulses.

In this paper, a kind of tightly coupled array (TCA) with time-domain beam scan is developed for the radiation of high-power ultrawideband (UWB) electromagnetic pulses, and the peak-power pattern is proposed to characterize the directivity. First, the active voltage standing wave ratio (AVSWR) bandwidth of the TCA is optimized, which is the precondition for the beam scan. It indicates that the lower-cutoff frequency (LCF) is inversely proportional to the total length of the whole array; an increase in the distance between the array and the ground plane could remarkably reduce the LCF; and an increase in the element number can also decrease the LCF because of the increase in length, but more elements would make the center elements difficult to match in the low-frequency range, so there is a limitation on the number of elements for a certain LCF. Based on these results, a six-element linear array is designed. Then, the definition of the peak-power pattern is proposed to characterize the directivity of the UWB pulsed antenna. Finally, the optimized six-element array is developed, and the measured working band is 276 MHz-6.4GHz (AVSWR < 3). The effective potential gain is 1.76, and it improves by 51.7% with a reduction in the aperture area by 68.4% compared with the previous TCA, which means that the aperture efficiency is remarkably improved. The half-power beam width of the developed TCA with the scan angle of 0° is 45°. The time-domain beam scan could be performed with time-delay feeding lines, and the maximum scan angle is over ±30° in the E-plane. The developed TCA can be applied for the generation of high-power electromagnetic environments for the study of intentional electromagnetic interference.

Natural Disasters are Not All Natural

For a half century, the military has been developing technologies to turn climate and extreme environmental phenomena into weapons.&#x0D; This study is a literature review, which was conducted with the following objectives: 1/ to expose the known powerful military technologies of climate and environmental modification; 2/ to emphasize that many extreme environmental events observed in recent years coincide with the effects that these military technologies are able to generate; 3/ to analyze the conclusions of the Intergovernmental Panel on Climate Change (IPCC) on the origins of the increase in natural disasters.&#x0D; The literature used comes from official sources: peer-reviewed scientific articles (except one); patents; intergovernmental organizations; military documents; policy documents; university documents; national newspapers; news agencies; writings by respected scientists in their fields.&#x0D; Results of the literature review reveal that HAARP (High-frequency Active Auroral Research Program), the most powerful ionospheric heater in operation, is able to influence climate. High-power electromagnetic pulses in the earth's crust, produced by a mobile magneto-hydrodynamic generator, is a technique developed since the 1970s to trigger earthquakes. Directed energy weapons, a real technology, can ignite destructive fires at range. For several years, official documents report effects on health and the environment similar in all aspects to those that would be detected if solar geoengineering by stratospheric aerosol injection, a climate-altering technique, was used. Due to numerous biases and a lack of objectivity, the IPCC's arguments on the causes of the growth in extreme environmental phenomena (heat and cold waves, storms, hurricanes, tornadoes, droughts, floods, wildfires, air pollution, etc.) are flawed. The solar hypothesis isn't appropriate either, given its low activity for several years.&#x0D; In conclusion, the use of military climatic and environmental modification technologies appears to be the most relevant explanation to understand the increase in natural disasters over the last 20 years.

Determination of Shielding Effectiveness of a Subnanosecond High-Power EM Interference by an Enclosure with Aperture Using Time Domain Approach

Determination of Shielding Effectiveness of a Subnanosecond High-Power EM Interference by an Enclosure with Aperture Using Time Domain Approach

Development of the EM Field in a Shielding Enclosure with Aperture after Interference Caused by a Subnanosecond High-Power Parallelly Polarized EM Plane Wave Pulse

Due to the increase in the threat of attacks with high-power electromagnetic (EM) pulses, there is great interest in metallic enclosures with high shielding effectiveness (SE). Necessary technological apertures in these enclosures reduce their effectiveness. Understanding the penetration and internal propagation of the high-power EM pulses into an apertured enclosure is fundamental to assessing the EM SE of the enclosure. In the present paper, results of the numerical simulations of development of the EM field in a shielding enclosure with aperture after the interference of a subnanosecond high-power EM plane wave pulse of the parallel polarization (having the duration of 0.3558 ns and the amplitudes of the electric and magnetic fields of 106 V/m and 2.6 × 103 A/m, respectively) are presented. The results obtained include 3D and 2D images , vector maps of the EM field developed inside the enclosure, and time-varying distributions of the electric charges formed on the inner walls of the enclosure. They revealed the mechanism of formation of the EM field inside the enclosure caused by the subnanosecond high-power parallelly polarized EM pulse. The EM field formed in the enclosure with aperture has the form of the electric and magnetic field interference structures. They are a superposition of the incident EM pulse field, which entered the enclosure through the aperture in the way described by the geometrical (ray) optics, the electric field generated by the electric charges formed on the aperture edges and inner sides of the walls of the enclosure, and the magnetic field generated by the surface current formed on the aperture edges and on the inner walls of the enclosure. The amplitudes of the electric and magnetic fields of the strongest EM interference structures decrease non-monotonically to about 0.7 × 105 V/m and 200 A/m at t = 5 ns. We found that the points in the enclosure are subjected to the disturbance of a long series of subnanosecond EM pulses, which we have called internal EM pulses. The amplitudes of these internal pulses are lower than those of the incident EM pulse. Nevertheless, they can pose a severe EM hazard inside the enclosure due to their large number (about 900 internal pulses in 30 ns). This means a fundamental change in the character of the EM disturbance caused by the subnanosecond pulse when the enclosure with aperture is used as a shield.

A New Approach to Formation and Directed Radiation of Powerful Short Radio Pulses

This article details a new method for formation and directional radiation of short high-power electromagnetic (EM) pulses, which is based on a wave analog of the Smith–Purcell effect. The presented device cycles through two stages. At the stage of energy accumulation, a slow wave of an open guiding structure interacts with a periodic chain of storage resonators and excites high-Q free field oscillations in each resonator of this chain. The phase of oscillations inside the storage resonators differs by a constant value, and the amplitude increases with time. At the radiation stage, the chain of storage resonators is opened to radiation (as it usually happens in active compressors of EM pulses), and short powerful pulses burst out into free space in strictly defined directions. The proposed design is considered in detail for the simplest model of a device. The results obtained during its rigorous electrodynamic analysis look rather promising; the continuation of this work can contribute to solving a number of urgent problems of physics and technology of millimeter and submillimeter waves.

Advances in Pulsed Power Mineral Processing Technologies

In Russia and globally, pulsed power technologies have been proposed based on the conversion of energy into a short-pulsed form and exposing geomaterials (minerals, rocks, and ores) to strictly dosed high-power pulsed electric and magnetic fields, beams of charged particles, microwave radiation, neutrons and X-ray quanta, and low-temperature plasma flows. Such pulsed energy impacts are promising methods for the pretreatment of refractory mineral feeds (refractory ores and concentration products) to increase the disintegration, softening, and liberation performance of finely disseminated mineral complexes, as well as the contrast between the physicochemical and process properties of mineral components. In this paper, we briefly review the scientific foundations of the effect of both high-power nanosecond electromagnetic pulses (HPEMP) and dielectric barrier discharge (DBD) in air on semiconductor ore minerals (sulfides, rare metals minerals) and rock-forming dielectric minerals. The underlying mechanisms of mineral intergrowth disintegration and changes in the structural and chemical states of the mineral surface when exposed to HPEMP and DBD irradiation are discussed. The high performance and potential limitations of pulsed energy impact and low-temperature plasma produced by DBD treatment of geomaterials are discussed in terms of the directional change in the process properties of the minerals to improve the concentration performance of refractory minerals and ores.

A Method to Evaluate the Performance of Ultra-Wideband Antennas for the Radiation of High-Power Electromagnetic Pulses

In this communication, a time-frequency joint method is proposed to evaluate the performance of ultrawideband (UWB) antennas for the radiation of high-power (HP) electromagnetic pulses. First, conventional antenna parameters, such as the efficiency, gain, and so on, are translated to UWB pulsed antennas from the energy perspective, so as to get several scalar antenna parameters, since energy in one pulse is finite. Thus, the power-spectrum weighted efficiency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _{e}$ </tex-math></inline-formula> ), directivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{e}$ </tex-math></inline-formula> ), and gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$G_{e}$ </tex-math></inline-formula> ) are proposed. Then, several electromagnetic norms of the radiating pulse are selected to characterize the sensitive parameters of the equipment under test (EUT). Based on these, several other scalar antenna parameters are proposed, which are the effective potential gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$G_{ep}$ </tex-math></inline-formula> ), pulse sharpening factor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PSF</i> ), and peaking impulse gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$G_{PI}$ </tex-math></inline-formula> ). Thus, a set of time-domain scalar criteria are proposed to evaluate the performance of HP-UWB antennas. These criteria can be calculated with the frequency functions of conventional antenna parameters, which demonstrate the inherent properties of one antenna. Finally, the performance of two kinds of typical HP-UWB antennas, namely the impulse radiating antenna and the combined antenna, is measured and compared with the proposed method. It indicates that, with the proposed method, one can not only get the inherent properties of one antenna in the frequency domain but also quantitatively compare the performance of different antennas with a given exciting pulse in the time domain with the proposed scalar antenna parameters.

Detection Circuits for System-Level Signal and Power Noises Due to High-Power Electromagnetic Pulses

Four types of circuits for detecting system-level noises due to high-power electromagnetic (HPEM) pulses have been proposed and implemented in compact modules. The detection circuit provides digital information about the level or polarity of noises generated at specific power or signal nets. The sensed data are directly saved in the hardware, which is free from malfunctions of the applied system. For characterization and evaluation of the proposed circuits, transmission line pulse (TLP) and damped sinusoidal (DS) sources were constructed. The operation threshold curves of each detection circuit were theoretically derived and validated by measurements using the TLP source. The proposed detection circuits were then applied to the radiated HPEM experiments with the DS source. From the operation data of the detectors, the system-level noises generated by the radiated HPEM waves were quantitatively analyzed based on the operation threshold curve of each detector. The proposed detection circuits can play a role of a noninvasive diagnosis method for evaluating the effects of HPEM pulses inside a target application system.

Effect of high-power electromagnetic pulses and dielectric barrier discharges on physicochemical and flotation properties of perovskite

The methods of FTIR, SEM&ndash;EDX, microhardness test, electrokinetic potential and contact angle measurements, as well as the sorption and flotation experiments are used to study the influence of high-power electromagnetic pulses (HPEMP) and dielectric barrier discharge (DBD) on the structural, physicochemical and flotation properties of perovskite (Afrikanda deposit). The analysis of FTIR data shows that short treatment times (t treat = 10 t 0&divide;30 s) lead to opposite changes in the surface condition of perovskite: oxidation (hydration) of the surface in case of HPEMP and deoxidizing (dehydration) under DBD. According to SEM results, the surface of perovskite undergoes destruction as a result of HPEMP and DBD treatment. The surface of some areas of the samples is modified with the formation and opening of deep parallel cracks, most likely due to the polysynthetic twinning typical of perovskite crystals; the subparallel pyramidal protrusions are also observed in some surface areas. The determined morphological changes cause softening and a monotonic decrease in the microhardness of the mineral surface with an increase of the HPEMP and DBD (plasma) treatment times (ttreat = 0 t 0&divide;150 s) by &Delta;HVmax V = 27 x 7&divide;33%. The effect of HPEMP and DBD on the physicochemical properties of the mineral surface represents a shift in the electrokinetic potential towards positive values, an increase in the contact angle (t treat = 10 t 0&divide;30 s), as well as the improved adsorption of the collector and the higher flotation activity of perovskite by ~ 10&ndash;15%. The authors express their gratitude to Candidate of Geological&nbsp;and Mineralogical Sciences E.V. Koporulina and to&nbsp;Candidate of Engineering Sciences N.E. Anashkina for their&nbsp;help in the experimentation.The study was supported by the Ministry of Science and&nbsp;Higher Education of the Russian Federation, Project No.&nbsp;13.1902.21.0018, Agreement No. 075-15-2020-802.

Numerical and Experimental Investigation of the Effects of Dimensional Parameters on Carbon-Nanotube-Coated Copper Plasma Limiter

The plasma limiter (PL) is a suitable method to protect electronic devices from high-power electromagnetic pulses. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S$ </tex-math></inline-formula> -band PL has target specifications of 100 kW of power handling capability, < 100 ns of response time, and < 0.5 dB of insertion loss. Carbon nanotube (CNT) can be used to reduce power losses and instrument corrosion under frequent electromagnetic attacks. This article used CNT-coated copper needles in a PL to increase the electric field for the rapid breakdown process. Furthermore, the impact of dimensional parameters (needle’s length, needle’s radius, and axial displacement of the needles) were investigated. The experiment was conducted at 1800 W of peak power and 25 ns of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S$ </tex-math></inline-formula> -band (2.45 GHz) microwave duration. In this case, the height of 19 mm and diameter of 1 mm were found to be the optimal needle parameters, in which the fastest breakdown of the electric field is available. The finite-element method was used by CST software to verify the experiment results. The transmission losses were < 5% in the normal state. The breakdown electric field threshold was ~431 kV/m near the atmospheric pressures. There was an error of < 1.28 in the case with the lowest compatibility.

Comparative study on high-voltage nanosecond pulses and dielectric barrier discharge effects on surface morphology and physico-chemical properties of natural pyrrhotite

In this paper we used analytical electron microscopy, potentiometric titration (electrode potential), sorption and flotation measurements and other methods to study changes in the surface morphology, electrochemical, and physicochemical properties of the natural pyrrhotite exposed to nonthermal action of the repetitive nanosecond high-power electromagnetic pulses and low-temperature plasma of dielectric barrier discharge in air at atmospheric pressure. As a result of exposure to high-voltage nanosecond pulses, a sharp shift in the electrode potential of pyrrhotite to the region of negative values caused a decrease in the sorption of the anionic collector on the mineral, a decrease in the hydrophobicity of the surface and flotation of the mineral was due to an increase in the content of oxidized ferric iron on the mineral surface. Dielectric barrier discharge treatment caused the shift of the electrode potential to the region of negative values (–60 mV) in the range of pH 9.7-12, which causes the effect of a decrease in the sorption and flotation activity of pyrrhotite. The advantages of using the short-term (10-30 seconds) energy impacts for structural and chemical modification of the surface and physicochemical properties of sulfide minerals of iron are shown.

Effects of massive electromagnetic pulses on the structural and chemical properties and leaching efficiency of eudialyte concentrate

Scanning electron microscopy (SEM) and infrared spectroscopy (IR) were used to study the influence of high-power nanosecond electromagnetic pulses (HPEMP) and dielectric barrier discharges (DBD) in air at the atmospheric pressure on the structural and chemical properties of eudialyte. The spectral data analysis has shown that highintensity electric fields initiate mineral surface fracturing due to the weakening and/or breaking of bonds in the structural fragments of the mineral framework (presumably, Si10O27, and Si9MO30). According to the SEM data, HPEMPs cause sample surface strength reduction with the formation of new surface reliefs in the range from parallel (texp = 30 s) to polygonal fractured shapes (texp = 60 and 90 s), depending on the electromagnetic pulse exposure time texp. Eudialyte grain micromorphology after the treatment under DBD conditions is distinctively characterized by the presence of imprints of electrical current breakdown microchannels of up to 3&ndash;4 &mu;m, with practically no microcracks or other defects occurring on the mineral surface. The intensifying effect of high-power electromagnetic pulses on the process of eudialyte concentrate acid leaching has been experimentally established. Zirconium recovery into the pregnant solution is improved by 3.4 to 4.3 % through HPEMP pretreatment and by 4.0 % through DBD exposure, with the total recovery of rare earth elements increasing by 1.1 to 1.7 %.This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation, project No. 13.1902.21.0018 (agreement No. 075-15-2020-802).

Generation of high-power electromagnetic pulses and its application to radiation effect research: A review

<p indent=0mm>This study reviews the research progress of high-power electromagnetic pulse generation. It introduces the physical model, different technologies, and the experimental generation of ultrafast, ultrashort, and ultra-high-power electromagnetic pulses. Progress on the radiation effects of electromagnetic pulses and the measured damage thresholds of microcontroller and photo-electronic devices are also discussed. Finally, future research prospects in this field are suggested.

Design of Compact Solid-State Modulator for High-Power Electromagnetic Pulse Generation

The proposed compact solid-state modulator for the generation of high-power electromagnetic (HPEM) pulses uses a lithium polymer battery as the input power source and is capable of achieving a 100-Hz pulse discharge rate with a peak voltage of 400 kV for 2 min. The developed pulse generator consists of two charging units. The primary charging unit is designed to work with 200-A battery current, which increases switching losses and temperature increments at the main switch. To compensate the problems, a half-bridge three-phase structure is connected to transformers via the proposed delta-star connection that decreases the turns ratio of the three-phase transformer effectively. Furthermore, the resonant components are intentionally placed on the secondary side of the three-phase transformer, which is characterized by low current and high voltage conditions. The secondary charging unit uses the resonance between the two capacitors, and the inductor must protect not only the controller, which is susceptible to HPEM pulse effects, but also the output rectifying diodes of the primary charging unit from the peak 20-kA pulse discharging effect. The design procedures and analysis are verified with simulations for each charging unit. The experimental results using various loads, including the actual tesla transformer, validate the system performance and confirm a 94% power efficiency with a peak power density of 431 W/L.

Antenna Array with TEM-Horn for Radiation of High-Power Ultra Short Electromagnetic Pulses

An antenna array with short shielded transverse electromagnetic horns (S-TEM-horns) for emitting high-power radiation of ultra-short electromagnetic pulses (USEMP) has been created and researched. The antenna unit consists of an ultra-wideband antenna array with four S-TEM horns, with each connected to a two-wire HF transmission line, and these four lines are connected to an antenna feeder. This feeder is connected to a semiconductor generator with the following parameters: a 50 Ohm connector, 10–100 kV high-voltage monopolar pulses, a rise time of about 0.1 ns, FWHM = 0.2–1 ns, and pulse repetition rates of 1–100 kHz. The antenna array was designed and optimized to achieve a high efficiency of about 100% for the antenna aperture by using a 2 × 2 array with S-TEM-horns, with shielding rectangular plates for the return current. The transient responses were studied by simulation using the electromagnetic 3D code “KARAT” at the time domain and experimentally with the use of our stripline sensor for measurement of the impulse electrical field with a 0.03 ns rise time and a 7 ns duration at the traveling wave. The radiators were emitting USEMP waves with a hyperband frequency spectrum of 0.1–6 GHz. The radiation with an amplitude of 5–30 kV/m of the E-field strength at a distance of up to 20 m was successfully applied to test the electronics for immunity to electromagnetic interference.

차폐망 및 접지형태에 따른 고출력 전자기 펄스에 대한 차폐성능 분석

차폐망 및 접지형태에 따른 고출력 전자기 펄스에 대한 차폐성능 분석

Cost Effective and Sustainable Test Methods to Investigate Vulnerabilities of EMP Attack on Existing Buildings Using Public Frequency Devices

High-power electromagnetic pulses are electromagnetic shock waves with strong energy, which can cause the destruction or malfunction of both electrical and electronic systems. The measurement of the electromagnetic wave shielding performance of buildings is effective for determining the level of EMP protection for each facility. However, it is extremely inefficient to practically measure the electromagnetic wave shielding performance using methods based on various standards for general buildings, in term of testing cost and time. Therefore, cost effective and sustainable test methods to investigate vulnerabilities of electromagnetic pulses attack on existing buildings using public frequency is proposed in this study. The study focuses on a simpler and more reliable method such as the use of broadcast or communication signals. From the results, it was concluded that the shielding performance can be measured approximately −45 dB using broadcast devices, −70 dB using walkie-talkie as simplified measurements of the electromagnetic-wave shielding performance. Therefore, if the test methods which are proposed in this study are allowed for preliminary investigation to find the vulnerabilities of existing buildings, cost and energy in the investigation can be reduced and it is expected to bring out frequency inspection and sustainable EMP protection performance of buildings.

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.

Development of a type of differential switched oscillator system for the radiation of mesoband high-power electromagnetic pulses.

In this Note, a type of Differential Switched Oscillator (DSWO) system is developed and compared with the conventional single-ended switched oscillator; the power capacity of the DSWO is twice with the same insulation level and twice total length. The DSWO system consists of a differential high-voltage pulsed source, a DSWO, and a pair of differential helical antennas. The differential pulsed source is based on the hydrogen thyratron and pulsed transformer whose peak voltage can theoretically reach ±100 kV to break down the high-pressure switch, whose limiting gas pressure is 25 atm; the DSWO is designed to generate a damped oscillation pulse with a central frequency of 300MHz, which is also the central frequency of the differential helical antennas. Thus, a damped oscillation pulse can be produced and radiated to generate high-power mesoband circularly polarized electromagnetic fields, and the axial ratio is 1.98. According to the measured results, the central frequency of the developed DSWO is 284MHz, the percent bandwidth of the radiating field is 11%, and the amplitude of the far-field effective potential is 105 kV.

Effect of the high-power electromagnetic pulses on the reactivity of the coal-water slurry in hot environment

An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated. In contrary to the previously investigated laser-induced fuel atomization that occurs at the room temperature, the pre-heated (to 400 K) slurry becomes dry enough to prevent the explosion-like steam formation. Thus, fuel does not atomize and the ignition does not accelerate. Furthermore, the absorption of several laser pulses leads to evident sintering of irradiated surface with following increase of the ignition delay time for up to 24%. Variation of the pulse energy in range 48–118 mJ (corresponding intensity up to 2.4 J·cm −2 ) leads to certain variation of the increase of ignition delay. The strong pulsed overheating of the coal water slurry which does not initiate the fine atomization of the fuel generally makes its ignition longer.