Pulsed Electromagnetic Wave Research Articles

Improving remote detection of radioactivity

After a nuclear power plant accident, for safety reasons it can be difficult for humans or even robots to get close enough to the facility to assess the situation. To get accurate information without putting people or equipment at risk, responders would benefit from better technology to sense radioactive material from afar. That could come from high-power pulsed electromagnetic waves, reports a team from Ulsan National Institute of Science & Technology (UNIST). First proposed in 2010 by the University of Maryland’s Gregory S. Nusinovich and colleagues, the approach involves using an antenna to direct high-intensity millimeter or terahertz waves at a target area. If material there is radioactive, γ radiation or α particles ionize the surrounding air, releasing free electrons. The interaction of the antenna-directed electromagnetic waves and ionized air induces plasma formation, and the plasma in turn reflects the electromagnetic waves back to the source site for detection. The

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.

Formation of plasmon pulses in the cooperative decay of excitons of quantum dots near a metal surface

The formation of pulses of surface electromagnetic waves in a metal/dielectric interface is considered in the process of cooperative decay of excitons of quantum dots distributed near a metal surface in a dielectric layer. It is shown that the efficiency of exciton energy transfer to excited plasmons can be increased by selecting the dielectric material with specified values of the complex permittivity. It is found that in the mean field approximation the semiclassical model of formation of plasmon pulses in the system under study is reduced to the pendulum equation with the additional term of nonlinear losses.

Resonant two-photon annihilation of an electron-positron pair in a pulsed electromagnetic wave

Two-photon annihilation of an electron-positron pair in the field of a plane low-intensity circularly polarized pulsed electromagnetic wave was studied. The conditions for resonance of the process which are related to an intermediate particle that falls within the mass shell are studied. In the resonant approximation the probability of the process was obtained. It is demonstrated that the resonant probability of two-photon annihilation of an electron-positron pair may be several orders of magnitude higher than the probability of this process in the absence of the external field. The obtained results may be experimentally verified by the laser facilities of the international megaprojects, for example, SLAC (National Accelerator Laboratory), FAIR (Facility for Antiproton and Ion Research), and XFEL (European X-Ray Free-Electron Laser).

Development of a Cluster Burst Pulse Generator Based on a SOS Diode for Medical Applications

SUMMARYThis work focuses on the design of a compact high‐power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for the cancer treatment. In the previous study, since the output voltage waveform of the pulsed power generator was damping oscillation, the duration of the burst pulse was under 100 ns. So the generator uses a magnetic switch instead of the gap switch and uses a SOS diode with current cutoff time of nanoseconds. The cluster pulse has six burst pulses that are repeated at 2 Mpps. The frequency of the burst pulse is 50 MHz. The peak output voltage is 7.5 kV.

Transformation of the Spatial Structure of an Optical Echo-Hologram Response by External Non-Resonant Pulses of Electromagnetic Standing Waves

It was shown that non-resonant electromagnetic standing wave pulses between exciting laser pulses during formation of a stimulated echo hologram transformed the wave front of the stimulated echo-hologram response.

Particle energy distributions and metastable atoms in transient low pressure interpulse microwave plasma

The electron energies and its distribution function are measured in non-equilibrium transient pulsed microwave plasmas in the interpulse regime using a retarding field electron energy analyzer. The plasmas are driven to different initial conditions by varying the electromagnetic (EM) wave pulse duration, peak power, or the wave frequency. Two cases of wave excitation are investigated: (i) short-pulse (pulse duration, tw ~ 1 μs), high-power (~60 kW) waves of 9.45 GHz and (ii) medium-pulse (tw ~ 20 μs), and moderate power waves of ~3 kW at 2.45 GHz. It is found that high-power, short-duration pulses lead to a significantly different electron energy probability function (EEPF) in the interpulse phase—a Maxwellian with a bump on the tail, although the average energy per pulse (~60 mJ) is maintained the same in the two modes of wave excitation. Electrons with energies >250 eV are found to exist in the discharge in the both cases. Another subset of experiments is performed to delineate the effect of the wave frequency and the peak power on EEPF. A traveling wave tube (TWT) amplifier based microwave source for generating pulsed plasma (tw = 230 μs) in a wide frequency range (6–18 GHz) is employed for this purpose. Further experiments on measurements of metastable density using optical emission spectroscopy and ion energy analyzer have been carried out. By tailoring the EEPF of the transient plasma and metastable densities, new applications in plasma processing, chemistry and biology can be realized in the interpulse phase of the discharge.

Pulsed electromagnetic wave exposure induces ultrastructural damage and upregulated expression of heat shock protein 70 in the rat adenohypophysis.

The aim of the present study was to investigate the ultrastructural damage and the expression of heat shock protein 70 (HSP70) in the rat adenohypophysis following pulsed electromagnetic wave (PEMW) exposure. The rats were randomly divided into four groups: Sham PEMW exposure, 1 x 10(4) pulses of PEMW exposure, 1 x 10(5) pulses of PEMW exposure and 3 x 10(5) pulses of PEMW exposure. Whole body radiation of 1 x 10(4) pulses, 1 x 10(5) pulses and 3 x 10(5) pulses of PEMW were delivered with a field strength of 100 kV/m. The rats in each group (n=6 in each) were sacrificed 12, 24, 48 and 96 h after PEMW exposure. Transmission electron microscopy was then used to detect the ultrastructural changes and immunocytochemistry was used to examine the expression of HSP70. Cellular damage, including mitochondrial vacuolation occurred as early as 12 h after PEMW exposure.More severe cellular damages, including cell degeneration and necrosis, occurred 24 and 48 h after PEMW exposure. The PEMW-induced cellular damage increased as the number of PEMW pulses increased. In addition, the expression of HSP70 significantly increased following PEMW exposure and peaked after 12 h. These findings suggested that PEMW induced ultrastructural damages in the rat adenohypophysis and that HSP70 may have contributed to the PEMW-induced adenohypophyseal damage.

SOSダイオードを用いた医療用クラスタバーストパルス発生装置の開発

This work focuses on the design of a compact high power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for the cancer treatment. In previous study, since the output voltage waveform of the pulsed power generator was damping oscillation, the duration of the burst pulse was under 100 ns. So the generator uses a magnetic switch instead of the gap switch and uses a SOS diode with current cutoff time of nanoseconds. The cluster pulse has 6 burst pulses that are repeated at 2 Mpps. The frequency of the burst pulse is 50 MHz. The peak output voltage is 7.5 kV.

10m高分布式负载有界波电磁脉冲模拟器的模式分析

10m高分布式负载有界波电磁脉冲模拟器的模式分析

S-band microwave-Induced thermo-acoustic tomography system

The technology of microwave-induced thermo-acoustic tomography that transmits electromagnetic wave pulses to the object and makes it absorb energy, can cause a rapid temperature rise in it. At the same time, a pressure wave will be generated instantaneouly, corresponding to generating an ultrasonic signal which can be detected by an ultrasonic sensor. After the ultrasonic signal is sampled and an image reconstructed, the image can reflect the characteristics of the electromagnetic energy absorbed by the object. The method combines a microwave imaging of high contrast and high resolution ultrasound imaging characteristics, hence verifies theoretically the feasibility of the thermo-acoustic imaging techniques for early breast cancer detection. In this study, we use S-band microwave pulse radiation source to radiate the biological tissue, and also make use of the circling mechanical motion systems to scan the tissue. In order to verify the imaging performance of the simulation experiments, we use both tumors, body and actual biological tissue as the samples of the experiments. The imaging reconstruction and comparative analysis can verify that the experimental system detects and distinguishes the tumor phantoms and the real biological tissue effectively. Results of the performance of high-resolution images and high contrast by the methods can provide further theoretical support for early detecting of breast cancer.

Transmission Design Based on Sonic Drilling Parameter

In order to overcome the shortcomings of the traditional drilling rig drilling parameters cable transmission technology for high cost and high fault, a drill pipe, which functions as the transmission medium is proposed, the sound waves as carrier of drilling parameter transmission method. The intelligent drill pipe based on the acoustic transmission technology has the advantages of reasonable design, low cost, convenient installation, which can effectively overcome the shortcomings of the past similar products using electromagnetic wave pulse low rate of signal transmission, the transmission distance near, cope with the wired data transmission mode of the high cost and high failure rate, meet the needs of the large-scale development of petroleum mining industry, series standardization, specialization and high grade direction, in order to provide technical support for marine resources detection.

Magnetic Field Homogeneity of Birdcage Coil for 4T MRI System with No Lumped Circuit Elements

In recent years, magnetic resonance imaging (MRI) systems that operate up to under 3T are being used in clinical practice in Japan. In order to achieve the requirements of higher image quality and shorter imaging times, devices that utilize high magnetic fields (> 3T) and high power electromagnetic (EM) wave pulses have been developed. The rise of the static magnetic field is proportional to the increase of the EM wave frequency which raises the issue of variation in capacitance used in the radio frequency (RF) coil for MRI system. In addition, increasing power causes problems of withstanding voltage and these approaches leads to generation of non-uniform magnetic field inside the RF coil. Therefore, we proposed a birdcage coil without the use of lumped circuit elements for MRI systems in previous study. However, it is difficult to fabricate this birdcage coil. Hence, simply-structured birdcage coil with no lumped circuit elements is desired. In this paper, we propose a simply-structured birdcage coil with no lumped circuit elements for a 4T MRI system. In addition, the authors investigated the input impedance and magnetic field distribution of the proposed coil by FDTD calculations and measurements. The results confirm that the proposed birdcage coil matches the performance of the conventional birdcage coil which includes several capacitors.

垂直极化平行板有界波电磁脉冲模拟器辐射近场的快速估算方法

For fast estimating the time-domain near-fields of flat-plate bounded wave electromagnetic pulse(EMP) simulator with vertical polarization, scattering transfer function method is used in time-domain simulation of this kind of simulator. A Gaussian pulse, whose effective frequency domain is wider than that of a given pulse source, is found firstly. And the time-domain response of electric fields at some testing points in the simulator excited by the Gaussian pulse source can be got by finite-difference time-domain (FDTD) method. Then the transient response of electric field at each testing point as the simulator excited by the given pulse source can be computed by Fourier transform, system transfer function and inverse Fourier transform. The results are well consistent with those got by FDTD method as the simulator is excited by the given pulse source directly. The method in this paper is useful for fast estimating radiation near-fields of a fixed simulator with different exciting sources. It has the advantages of reducing FDTD simulation time, saving much computing time and CPU storage especially for medium or large simulators.

分布式负载平行板有界波电磁脉冲模拟器的模拟分析

分布式负载平行板有界波电磁脉冲模拟器的模拟分析

Broadband electromagnetic characterization of a100 Ωtraveling-wave electrode by measuring scattering parameters

The Single Bunch Selector (SBS) will be used on the Spiral2 linear accelerator to reduce the rate of high energy bunches reaching the target with, in principle, no residual particles from the suppressed bunches. For this purpose, a pulsed electromagnetic wave will travel along the $100\text{ }\text{ }\ensuremath{\Omega}$ microstrip meander line electrode of the SBS. In this work we describe the broadband accurate characterization of the electrode electromagnetic features. The method applied here leads to the analytical determination of complex characteristic impedance, propagation constant, and group velocity from a measurement of the $50\text{ }\text{ }\ensuremath{\Omega}$ scattering parameters on the meander transmission line. Particular care is given to the de-embedding phase of the transitions required to connect the meander electrode to the measurement device.

Conservation of Energy Momentum and the Metric of a Gravitational or Electromagnetic Plane Wave Pulse

We use conservation of energy and momentum to show the metric of a gravitational or electromagnetic plane wave pulse is flat.

Analytic Iterative Solution of Electromagnetic Pulse Coupling to Multiconductor Transmission Lines

This paper provides an efficient iterative solution in the frequency domain for electromagnetic pulse (EMP) radiated field coupling to multiconductor transmission lines (MTLs) based on distributed analytical representation of the exciting sources and iterative technique originated from waveform relaxation. The method consists of two kinds of iterations, the first is that the incoming EMP wave couples to each conductor while the effects of neighboring conductors were neglected; the second is that each conductor will be not only subject to the illumination of the EMP wave, but also influenced by the virtual sources which are the induced voltages and currents of the neighboring conductors at the previous iteration. The key highlights of the proposed method are that the induced voltage and current at each iteration are considered as the virtual distributed exciting sources for next iteration, and the integrals were solved analytically by the Baum-Liu-Tesche equation, leading to a pretty good efficiency and quick convergence for most real cases. The validation results over a wide range show that the proposed method could efficiently handle EMP coupling to MTLs with a large number of conductors and the accuracy of the solutions is closely related to the number of iterations allowing the flexibility to choose between the accuracy and the time cost.

Ground penetrating abilities of a new coherent radio wave and microwave imaging spectrometer

The early use of synthetic aperture radar (SAR) and lidar systems from aircraft and space shuttles revealed the ability of the signals to penetrate the ground surface. Atomic dielectric resonance (ADR) technology was developed as an improvement over SAR and ground penetrating radar (GPR) to achieve deeper penetration of the Earth's subsurface through the creation and use of a novel type of coherent beam. When pulsed electromagnetic radio waves pass through a material, they generate measurable responses in terms of energy, frequency, and phase relationships. A deployment of the ADR equipment in a field study of a measured section of Dinantian sediments in a disused quarry at Cults, Fife, Scotland, has confirmed the ability of the method to distinguish the lithologic type and their respective thickness ranging from limestones through sandstones, siltstones, seatearths, and coals. Borehole data were used to corroborate the ADR imaging spectrometer. The signal penetrated more deeply into the ground than the 20 m height of the exposed rock section, and it showed good correlation with records from two nearby boreholes that extend to lower levels. Reliable lithological recognition at ground penetration of more than 90 m had been achieved. ADR was also deployed over deeper borehole sites in the Limestone Coal Formation at Higham and Lathones, Fife, Scotland. Here the signal was shown to penetrate the subsurface to depths of 225 and 580 m, respectively. A subsequent field deployment of ADR at Cousland, Midlothian, Scotland, demonstrated subsurface penetration in the Lower Limestone Formation by ADR to 700 m – as confirmed from nearby boreholes.

Propagation characteristics of time reversal pulsed electromagnetic waves in double negative materials

With the full time-domain electromagnetic simulation technique, the time-domain propagation properties such as the temporal pulse waveform, the pulse compression and the electric field distribution inside the material are comparably investigated by transmitting the time-reversal pulsed electromagnetic wave and the pulsed electromagnetic wave through the double negative material of the Smith structure, respectively. The results show that after the time-reversal pulsed electromagnetic wave passes through the double negative material, the received electromagnetic wave exhibits remarkable spatial and temporal focusing at the location of the initial excitation. The most interesting physical phenomenon is that the peak values of the electric field inside the double negative material become smaller and tend to be uniform in the magnitude. These novel physical phenomena would be very helpful for developing new electronic devices and systems with double negative materials for the purpose of high power applications.