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Sample records for absorbing electromagnetic waves

  1. Experimental results on indoor electromagnetic wave absorber using magnetic wood

    NASA Astrophysics Data System (ADS)

    Oka, Hideo; Narita, Koichi; Osada, Hiroshi; Seki, Kyoushirou

    2002-05-01

    The purpose of this paper is to propose a new type of indoor electromagnetic wave absorber using magnetic wood. This magnetic wood has good electromagnetic wave absorbing characteristics, a low specific gravity, a wood texture and other wood characteristics and can be easily processed. Electromagnetic wave absorbing characteristics were measured for four types of magnetic wood. The sandwich-type magnetic wood demonstrated the best wave absorbing characteristics among the four types of magnetic wood that were studied. The experimental results showed that the proposed indoor electromagnetic wave absorber can be used to suppress the transmission and reception of cellular phone and Personal Handy Phone System (PHS) signals and can be used as a cross protection for indoor wireless Local Area Networks (LAN). This wood can be processed for use in furniture, building materials, and other applications.

  2. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    NASA Astrophysics Data System (ADS)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, Youngpak

    2015-09-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  3. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    PubMed Central

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-01-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet–height and diameter– and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials. PMID:26354891

  4. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets.

    PubMed

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-09-10

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  5. Electromagnetic Wave Absorbing Properties of Amorphous Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-07-01

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7-50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was -25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at -10 dB was up to 5.8 GHz within the frequency range of 2-18 GHz.

  6. Electromagnetic wave absorbing properties of amorphous carbon nanotubes.

    PubMed

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-07-10

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7-50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was -25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at -10 dB was up to 5.8 GHz within the frequency range of 2-18 GHz.

  7. Electromagnetic Wave Absorbing Properties of Amorphous Carbon Nanotubes

    PubMed Central

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-01-01

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7–50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was −25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at −10 dB was up to 5.8 GHz within the frequency range of 2–18 GHz. PMID:25007783

  8. Role of surface electromagnetic waves in metamaterial absorbers.

    PubMed

    Chen, Wen-Chen; Cardin, Andrew; Koirala, Machhindra; Liu, Xianliang; Tyler, Talmage; West, Kevin G; Bingham, Christopher M; Starr, Tatiana; Starr, Anthony F; Jokerst, Nan M; Padilla, Willie J

    2016-03-21

    Metamaterial absorbers have been demonstrated across much of the electromagnetic spectrum and exhibit both broad and narrow-band absorption for normally incident radiation. Absorption diminishes for increasing angles of incidence and transverse electric polarization falls off much more rapidly than transverse magnetic. We unambiguously demonstrate that broad-angle TM behavior cannot be associated with periodicity, but rather is due to coupling with a surface electromagnetic mode that is both supported by, and well described via the effective optical constants of the metamaterial where we achieve a resonant wavelength that is 19.1 times larger than the unit cell. Experimental results are supported by simulations and we highlight the potential to modify the angular response of absorbers by tailoring the surface wave.

  9. Thin Perfect Absorbers for Electromagnetic Waves: Theory, Design, and Realizations

    NASA Astrophysics Data System (ADS)

    Ra'di, Y.; Simovski, C. R.; Tretyakov, S. A.

    2015-03-01

    With recent advances in nanophotonics and nanofabrication, considerable progress has been achieved in realizations of thin composite layers designed for full absorption of incident electromagnetic radiation, from microwaves to the visible. If the layer is structured at a subwavelength scale, thin perfect absorbers are usually called "metamaterial absorbers," because these composite structures are designed to emulate some material responses not reachable with any natural material. On the other hand, many thin absorbing composite layers were designed and used already in the time of the introduction of radar technology, predominantly as a means to reduce radar visibility of targets. In view of a wide variety of classical and new topologies of optically thin metamaterial absorbers and plurality of applications, there is a need for a general, conceptual overview of the fundamental mechanisms of full absorption of light or microwave radiation in thin layers. Here, we present such an overview in the form of a general theory of thin perfectly absorbing layers. Possible topologies of perfect metamaterial absorbers are classified based on their fundamental operational principles. For each of the identified classes, we provide design equations and give examples of particular realizations. The concluding section provides a summary and gives an outlook on future developments in this field.

  10. Parametric study of electromagnetic waves propagating in absorbing curved S ducts

    NASA Technical Reports Server (NTRS)

    Baumeister, Kenneth J.

    1989-01-01

    A finite-element Galerkin formulation has been developed to study attenuation of transverse magnetic (TM) waves propagating in two-dimensional S-curved ducts with absorbing walls. In the frequency range where the duct diameter and electromagnetic wave length are nearly equal, the effect of duct length, curvature (duct offset), and absorber wall thickness was examined. For a given offset in the curved duct, the length of the S-duct was found to significantly affect both the absorptive and reflective characteristics of the duct. For a straight and a curved duct with perfect electric conductor terminations, power attenuation contours were examined to determine electromagnetic wall properties associated with maximum input signal absorption. Offset of the S-duct was found to significantly affect the value of the wall permittivity associated with the optimal attenuation of the incident electromagnetic wave.

  11. Microwave absorbance properties of zirconium–manganese substituted cobalt nanoferrite as electromagnetic (EM) wave absorbers

    SciTech Connect

    Khan, Kishwar Rehman, Sarish

    2014-02-01

    Highlights: • Good candidates for EM materials with low reflectivity. • Good candidates for broad bandwidth at microwave frequency. • Microwave absorbing bandwidth was modulated simply by manipulating the Zr–Mn. • Higher the Zr–Mn content, the higher absorption rates for the electromagnetic radiation. • The predicted reflection loss shows that this can be used for thin ferrite absorber. - Abstract: Nanocrystalline Zr–Mn (x) substituted Co ferrite having chemical formula CoFe{sub 2−2x}Zr{sub x}Mn{sub x}O{sub 4} (x = 0.1–0.4) was prepared by co-precipitation technique. Combining properties such as structural, electrical, magnetic and reflection loss characteristics. Crystal structure and surface morphology of the calcined samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). By using two point probe homemade resistivity apparatus to find resistivity of the sample. Electromagnetic (EM) properties are measured through RF impedance/materials analyzer over 1 MHz–3 GHz. The room-temperature dielectric measurements show dispersion behavior with increasing frequency from 100 Hz to 3 MHz. Magnetic properties confirmed relatively strong dependence of saturation magnetization on Zr–Mn composition. Curie temperature is also found to decrease linearly with addition of Zr–Mn. Furthermore, comprehensive analysis of microwave reflection loss (RL) is carried out as a function of substitution, frequency, and thickness. Composition accompanying maximum microwave absorption is suggested.

  12. Study on the characteristics of magneto-sensitive electromagnetic wave-absorbing properties of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Yang, Pingan; Fu, Jie; Liu, Shuzhi; Qi, Song

    2016-08-01

    Magnetorheological (MR) materials are a class of materials whose mechanical and electrical properties can be reversible controlled by the magnetic field. In this study, we pioneered research on the effect of a uniform magnetic field with different strengths and directions on the microwave-absorbing properties of magnetorheological elastomers (MREs), in which the ferromagnetic particles are flower-like carbonyl iron powders (CIPs) prepared by an in situ reduction method. The electromagnetic (EM) absorbing properties of the composites have been analyzed by vector network analysis with the coaxial reflection/transmission technique. Under the magnetic field, the columnar or chainlike structures were formed, which allows EM waves to penetrate. Meanwhile, stronger Debye dipolar relaxation and attenuation constant have been obtained when changing the direction of the applied magnetic field. Compared with untreated MREs, not only have the minimum reflection loss (RL) and the effective absorption bandwidth (below -20 dB) greatly increased, the frequencies of the absorbing peaks shift about 15%. This suggests that MREs are a magnetic-field-sensitive electromagnetic wave-absorbing material and have great potential in applications such as in anti-radar camouflage, due to the fact that radar can continuously conduct detection at many electromagnetic frequencies, while the MR materials can adjust the microwave-absorption peak according to the radar frequency.

  13. One-way absorber for linearly polarized electromagnetic wave utilizing composite metamaterial.

    PubMed

    Zhao, Junming; Sun, Liang; Zhu, Bo; Feng, Yijun

    2015-02-23

    This paper presents the proposal and practical design of a one-way absorber for selective linearly polarized electromagnetic (EM) wave. The EM wave polarization rotation property has been combined with polarization selective absorption utilizing a composite metamaterial slab. The energy of certain linearly polarized EM wave can be absorbed along one particular incident direction, but will be fully transmitted through the opposite direction. For the cross polarized wave, the direction dependent propagation properties are totally reversed. A prototype designed with a total slab thickness of only one-sixth of the operating wavelength is verified through both full-wave simulation and experimental measurement in the microwave regime. It achieves absorption efficiency over 83% along one direction, while transmission efficiency over 83% along the opposite direction for one particular linearly polarized wave. The proposed one-way absorber can be applied in EM devices achieving asymmetric transmission for linearly polarized wave or polarization control. The composite metamaterial that combines different functionalities into one design may provide more potential in metamaterial designs for various applications.

  14. Investigation of Electromagnetic Wave Absorber Based on Carbon Fiber Reinforced Aerated Concrete, Using Time-Domain Method

    NASA Astrophysics Data System (ADS)

    Laukaitis, A.; Sinica, M.; Balevičius, S.; Levitas, B.

    2008-03-01

    The electromagnetic wave absorbers prepared from autoclaved aerated concrete containing carbon fibers as additions in the shape of slabs with pyramids cut on one plane of these slabs were tested using dc microwave source and the time-domain method. It was demonstrated that autoclaved aerated concrete allows one to fabricate electromagnetic wave absorbers which have a reflection coefficient up to -30 dB in the frequency range from 2 GHz to 18 GHz.

  15. Electromagnetic Wave Absorbing Technique Using Periodic Patterns for Low RCS Patch Array Antenna

    NASA Astrophysics Data System (ADS)

    Jang, Hong-Kyu; Lee, Yeon-Gwan; Shin, Jae-Hwan; Kim, Chun-Gon

    2013-07-01

    This paper presents an electromagnetic wave absorbing technique to reduce a radar cross-section (RCS) of a patch array antenna without compromising their antenna performance. The technique is based on periodic patterns, which is made of resistive materials. The 2×2 patch array antenna with a resonance frequency of 3.0 GHz was designed and fabricated. To reduce the RCS of the patch array antenna, the periodic patterns using a square patch element were proposed and applied to the surface between the four antenna patches. The printed lossy periodic patterns have radar absorbing performance at 12.0 GHz frequency. The measured results show that the lossy periodic patterns have no significant effect on the antenna radiation performance. On the other hand, the RCS is reduced by more than 98% compared to the conventional antenna at the target frequency.

  16. Gigahertz range electromagnetic wave absorbers made of amorphous-carbon-based magnetic nanocomposites

    NASA Astrophysics Data System (ADS)

    Liu, Jiu Rong; Itoh, Masahiro; Horikawa, Takashi; Machida, Ken-Ichi; Sugimoto, Satoshi; Maeda, Toru

    2005-09-01

    Nanocomposite magnetic materials α-Fe/C(a), Fe2B/C(a), and Fe1.4Co0.6B/C(a) were prepared by mechanically grinding α-Fe, Fe2B, or Fe1.4Co0.6B with amorphous carbon [C(a)] powders. Complex permittivity, permeability, and electromagnetic wave absorption properties of resin compacts containing 40-vol % composite powders of α-Fe/C(a), Fe2B/C(a), and Fe1.4Co0.6B/C(a) were characterized according to a conventional reflection/transmission technique. The real part (ɛr') and imaginary part (Vr'') of the relative permittivity are low and almost independent of frequency between 0.05 and 40 GHz. The Imaginary part (μr'') of the relative permeability exhibited wide peaks in the 1-9-GHz range for α-Fe/C(a), in the 2-18-GHz range for Fe2B/C(a), and in the 18-40-GHz range for Fe1.4Co0.6B/C(a) owing to their different magnetocrystalline anisotropy field (HA) values. Consequently, the resin compacts of 40-vol % α-Fe/C(a), Fe2B/C(a), and Fe1.4Co0.6B/C(a) powders provided good electromagnetic (em) wave absorption performances (reflection loss<-20 dB) in ranges of 4.3-8.2 GHz (G band), 7.5-16.0 GHz (X band), and 26.5-40 GHz (Q band) over absorber thicknesses of 1.8-3.3, 1.2-2.2, and 0.63-0.82 mm, respectively. Our experimental results demonstrate that the amorphous-carbon-based magnetic nanocomposites are promising for the application to produce thin and light EM wave absorbers.

  17. Electromagnetic power absorber

    NASA Technical Reports Server (NTRS)

    Iwasaki, R. S. (Inventor)

    1979-01-01

    A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

  18. Iron based carbon nanocomposites for electromagnetic wave absorber with wide bandwidth in GHz range

    NASA Astrophysics Data System (ADS)

    Liu, J. R.; Itoh, M.; Horikawa, T.; Taguchi, E.; Mori, H.; Machida, K.

    2006-02-01

    The electromagnetic wave absorption properties of resin compacts containing 40 vol. % composite powders of α-Fe/C(a), and Fe3C/C(a) were characterized in a frequency range of 0.05 26.5 GHz, according to a conventional reflection/transmission technique. The real part (ɛr ') and the imaginary part (ɛr '') of relative permittivity were constantly low in the 2 14 GHz (ɛr '= ˜12.4 and ɛr ''= ˜0.6) for α-Fe/C(a) resin composites, and in the 1 26.5 GHz (ɛr '= ˜9.6 and ɛr ''= ˜0.8) for Fe3C/C(a) ones. The imaginary part (μr '') of relative permeability exhibited wide peaks in the 1 9 GHz range for α-Fe/C(a), and in the 2 26.5 GHz range for Fe3C/C(a) owing to their different magnetocrystalline anisotropy field values. Consequently, the resin compacts with 40 vol. % α-Fe/C(a), and Fe3C/C(a) powders provided good electromagnetic wave absorption performances (reflection loss <-20 dB) in ranges of 4.3 8.2 GHz, and 9 26.5 GHz over absorber thicknesses of 1.8 3.3 mm, and 1.0 2.4 mm, respectively.

  19. Interaction of Electromagnetic Waves with Two-Dimensional Metal Covered with Radar Absorbing Material and Plasma

    NASA Astrophysics Data System (ADS)

    Lan, Chaohui; Hu, Xiwei; Jiang, Zhonghe

    2008-12-01

    A two-dimensional metal model is established to investigate the stealth mechanisms of radar absorbing material (RAM) and plasma when they cover the model together. Using the finite-difference time-domain (FDTD) method, the interaction of electromagnetic (EM) waves with the model can be studied. In this paper, three covering cases are considered: a. RAM or plasma covering the metal solely; b. RAM and plasma covering the metal, while plasma is placed outside; c. RAM and plasma covering the metal, while RAM is placed outside. The calculated results show that the covering order has a great influence on the absorption of EM waves. Compared to case a, case b has an advantage in the absorption of relatively high-frequency EM waves (HFWs), whereas case c has an advantage in the absorption of relatively low-frequency EM waves (LFWs). Through the optimization of the parameters of both plasma and RAM, it is hopeful to obtain a broad absorption band by RAM and plasma covering. Near-field attenuation rate and far-field radar cross section (RCS) are employed to compare the different cases.

  20. Coupling Hollow Fe3O4-Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material.

    PubMed

    Qu, Bin; Zhu, Chunling; Li, Chunyan; Zhang, Xitian; Chen, Yujin

    2016-02-17

    We developed a strategy for coupling hollow Fe3O4-Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4-Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach -30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4-Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

  1. Metal-organic framework nanoparticles decorated with graphene: A high-performance electromagnetic wave absorber

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Zhang, Wenzhi; Wu, Xinming; Luo, Chunyan; Liang, Tan; Yan, Gang

    2016-10-01

    A novel metal organic framework (MOF) coated RGO was fabricated by a one-step method. The morphology and microstructure of MOF-53(Fe)/RGO composite were characterized by XRD and TEM. The electromagnetic parameters indicate that MOF-53(Fe)/RGO composite shows enhanced electromagnetic absorption properties compared with MOF-53(Fe). The maximum RL can reach -25.8 dB at 15.4 GHz and the absorption bandwidth with the reflection loss exceeding -10 dB is 5.9 GHz (from 12.1 to 18 GHz) with the thickness of 2 mm. The possible absorption mechanism was also investigated in detail. Our results indicate the potential application of MOF/RGO composite as a more efficient microwave absorber.

  2. Porous CNTs/Co Composite Derived from Zeolitic Imidazolate Framework: A Lightweight, Ultrathin, and Highly Efficient Electromagnetic Wave Absorber.

    PubMed

    Yin, Yichao; Liu, Xiaofang; Wei, Xiaojun; Yu, Ronghai; Shui, Jianglan

    2016-12-21

    Porous carbon nanotubes/cobalt nanoparticles (CNTs/Co) composite with dodecahedron morphology was synthesized by in situ pyrolysis of the Co-based zeolitic imidazolate framework in a reducing atmosphere. The morphology and microstructure of the composite can be well tuned by controlling the pyrolysis conditions. At lower pyrolysis temperature, the CNTs/Co composite is composed of well-dispersed Co nanoparticles and short CNT clusters with low graphitic degree. The increase of pyrolysis temperature/time promotes the growth and graphitization of CNTs and leads to the aggregation of Co nanoparticles. The optimized CNTs/Co composite exhibits strong dielectric and magnetic losses as well as a good impedance matching property. Interestingly, the CNTs/Co composite displays extremely strong electromagnetic wave absorption with a maximum reflection loss of -60.4 dB. More importantly, the matching thickness of the absorber is as thin as 1.81 mm, and the filler loading of composite in the matrix is only 20 wt %. The highly efficient absorption is closely related to the well-designed structure and the synergistic effect between CNTs and Co nanoparticles. The excellent absorbing performance together with lightweight and ultrathin thickness endows the CNTs/Co composite with the potential for application in the electromagnetic wave absorbing field.

  3. A wormhole-like porous carbon/magnetic particles composite as an efficient broadband electromagnetic wave absorber

    NASA Astrophysics Data System (ADS)

    Fang, Jiyong; Liu, Tao; Chen, Zheng; Wang, Yan; Wei, Wei; Yue, Xigui; Jiang, Zhenhua

    2016-04-01

    A method combining liquid-liquid phase separation and the pyrolysis process has been developed to fabricate the wormhole-like porous carbon/magnetic nanoparticles composite with a pore size of about 80 nm (WPC/MNPs-80). In this work, the porous structure was designed to enhance interaction between the electromagnetic (EM) wave and the absorber, while the magnetic nanoparticles were used to bring about magnetic loss ability. The structure, morphology, porosity and magnetic properties of WPC/MNPs-80 were investigated in detail. To evaluate its EM wave attenuation performance, the EM parameters of the absorber and wax composite were measured at 2-18 GHz. WPC/MNPs-80 has an excellent EM wave absorbency with a wide absorption band at a relatively low loading and thin absorber thickness. At the absorber thickness of 1.5 and 2.0 mm, minimum RL values of -29.2 and -47.9 dB were achieved with the RL below -10 dB in 12.8-18 and 9.2-13.3 GHz, respectively. The Co and Fe nanoparticles derived from the chemical reduction of Co0.2Fe2.8O4 can enhance the graphitization process of carbon and thus improve dielectric loss ability. Polarizations in the nanocomposite absorber also play an important role in EM wave absorption. Thus, EM waves can be effectively attenuated by dielectric loss and magnetic loss through multiple reflections and absorption in the porous structure. WPC/MNPs-80 could be an excellent absorber for EM wave attenuation; and the design strategy could be extended as a general method to synthesize other high-performance absorbers.A method combining liquid-liquid phase separation and the pyrolysis process has been developed to fabricate the wormhole-like porous carbon/magnetic nanoparticles composite with a pore size of about 80 nm (WPC/MNPs-80). In this work, the porous structure was designed to enhance interaction between the electromagnetic (EM) wave and the absorber, while the magnetic nanoparticles were used to bring about magnetic loss ability. The structure

  4. Electromagnetic scattering by pyramidal and wedge absorber

    NASA Technical Reports Server (NTRS)

    Dewitt, Brian T.; Burnside, Walter D.

    1988-01-01

    Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for near-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength.

  5. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  6. Substitution effect of (Mn, Ti) to the dielectric properties of barium-strontium hexaferrite for absorbing electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Repi, V. Vekky R.; Manaf, Azwar

    2012-07-01

    The objective of this work is to evaluate the ability of Mn-Ti substituted barium-strontium hexaferrite to absorb high frequency electromagnetic wave. To accomplish this objective, Mn-Ti substituted barium strontium hexaferrite of Ba0.5Sr0.5Fe12-x(Mn0.5Ti0.5)x with x = 0.1, x=0.3, x=0.5 were prepared through mechanical alloying route. Phase identification of the material obtained from XRD pattern indicating that the material is single phase for all variations of x. Coercivity and the remanent obtained by analyzing the hysteresis curve. The lowest coercivity at x = 0.5 for 77.86 kA/m but also lower the remanent of 0.088 kA/m. Dielectric properties of the material traced by calculating the value of permittivity and permeability of the material that was obtained with the parameters of the scattering vector network analyzer (VNA) in the 8GHz to 12GHz range.

  7. Substitution effect of (Mn, Ti) to the dielectric properties of barium-strontium hexaferrite for absorbing electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Vekky, V.; Repi, R.; Manaf, Azwar

    2012-06-01

    The objective of this work is to evaluate the ability of Mn-Ti substituted barium-strontium hexaferrite to absorb high frequency electromagnetic wave. To accomplish this objective, Mn-Ti substituted barium strontium hexaferrite of Ba0.5Sr0.5Fe12-x(Mn0.5Ti0.5)x with x = 0.1, x=0.3, x=0.5 were prepared through mechanical alloying route. Phase identification of the material obtained from XRD pattern indicating that the material is single phase for all variations of x. Coercivity and the remanent obtained by analyzing the hysteresis curve. The lowest coercivity at x = 0.5 for 77.86 kA/m but also lower the remanent of 0.088 kA/m. Dielectric properties of the material traced by calculating the value of permittivity and permeability of the material that was obtained with the parameters of the scattering vector network analyzer (VNA) in the 8GHz to 12GHz range.

  8. Analysis of Wave Propagation in Stratified Structures Using Circuit Analogues, with Application to Electromagnetic Absorbers

    ERIC Educational Resources Information Center

    Sjoberg, Daniel

    2008-01-01

    This paper presents an overview of how circuit models can be used for analysing wave propagation in stratified structures. Relatively complex structures can be analysed using models which are accessible to undergraduate students. Homogeneous slabs are modelled as transmission lines, and thin sheets between the slabs are modelled as lumped…

  9. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  10. Propagation of an electromagnetic wave in an absorbing anisotropic medium and infrared transmission spectroscopy of liquid crystals.

    PubMed

    Scaife, B K P; Vij, J K

    2005-05-01

    The theory of absorbance is developed for the entire electromagnetic spectrum of radiation in a semi-infinite anisotropic medium with a second rank dielectric tensor, the elements of which are complex and frequency dependent. The theory of the absorbance A(omega,theta) of an optically anisotropic liquid in an infrared (IR) test cell is then outlined and applied to IR transmission experiments. A formula for the dependence of A(omega,theta), on theta (theta being the angle between the electric vector and the principal optical axis) is derived from first principles. The formula, for radiation of angular frequency omega, viz, A(omega,theta)=-log(10)[10(-A(omega,0))cos(2)theta+10(-A(omega,pi2))sin(2)theta] is in agreement with that proposed by Jang, Park, Maclennan, Kim, and Clark [Ferroelectrics 180, 213 (1996) ] and confirms some of the work of Kocot, Wrzalik, and Vij [Liq. Cryst. 21, 147 (1996)]. The comments on this formula by Jang, Park, Kim, Glaser, and Clark [Phys. Rev. E 62, 5027 (2000)], and by Kocot et al. are discussed. The absorbance A(omega,0) and A(omega,pi2) have been expressed in terms of the optical properties of the material and the dimensions of the cell.

  11. Characteristics of the Electromagnetic Wave Absorbers of Composites Made of Ni-Zn Ferrite and Isolated SiO2 Particles

    NASA Astrophysics Data System (ADS)

    Kusunoki, Hiroki; Hiraki, Kiyohiro; Kondo, Takatoshi; Takada, Kazushi; Yoshikado, Shinzo

    It is found from simulation study that electromagnetic wave absorbers made of composites of Ni-Zn ferrite and SiO2 particles, which are mutually isolated each other in the continuous medium of Ni-Zn ferrite, show absorption in the frequency region both below and above 1GHz. The spray method is proposed to fabricate such composites in this study. The thin films of Ni-Zn ferrite can be coated on the surface of SiO2 particles by the spray thin film deposition method. It is confirmed by XRD and the electromagnetic characteristics measurement. The measured complex permeability approached to the calculated result using the isolation model of SiO2 particles in the Ni-Zn ferrite medium than using Lichtenecker’s logarithm mixed low.

  12. A simple, one-step hydrothermal approach to durable and robust superparamagnetic, superhydrophobic and electromagnetic wave-absorbing wood

    PubMed Central

    Wang, Hanwei; Yao, Qiufang; Wang, Chao; Fan, Bitao; Sun, Qingfeng; Jin, Chunde; Xiong, Ye; Chen, Yipeng

    2016-01-01

    In this work, lamellar MnFe2O4 was successfully planted on a wood surface through the association of hydrogen bonds via the one-pot hydrothermal method. Simultaneously, the fluoroalkylsilane (FAS-17) on the surface of the MnFe2O4 layer formed long-chain or network macromolecules through a poly-condensation process and provided a lower surface energy on the wood surface. The MnFe2O4/wood composite (FMW) presented superior superparamagnetism, superhydrophobicity and electromagnetic wave absorption performance. The results indicated a saturation magnetization of the FMW with excellent superparamagnetism of 28.24 emu·g−1. The minimum value of reflection loss of the FMW reached −8.29 dB at 16.39 GHz with a thickness of 3 mm. Even after mechanical impact and exposure to corrosive liquids, the FMW still maintained a superior superhydrophobicity performance. PMID:27748420

  13. A simple, one-step hydrothermal approach to durable and robust superparamagnetic, superhydrophobic and electromagnetic wave-absorbing wood

    NASA Astrophysics Data System (ADS)

    Wang, Hanwei; Yao, Qiufang; Wang, Chao; Fan, Bitao; Sun, Qingfeng; Jin, Chunde; Xiong, Ye; Chen, Yipeng

    2016-10-01

    In this work, lamellar MnFe2O4 was successfully planted on a wood surface through the association of hydrogen bonds via the one-pot hydrothermal method. Simultaneously, the fluoroalkylsilane (FAS-17) on the surface of the MnFe2O4 layer formed long-chain or network macromolecules through a poly-condensation process and provided a lower surface energy on the wood surface. The MnFe2O4/wood composite (FMW) presented superior superparamagnetism, superhydrophobicity and electromagnetic wave absorption performance. The results indicated a saturation magnetization of the FMW with excellent superparamagnetism of 28.24 emu·g‑1. The minimum value of reflection loss of the FMW reached ‑8.29 dB at 16.39 GHz with a thickness of 3 mm. Even after mechanical impact and exposure to corrosive liquids, the FMW still maintained a superior superhydrophobicity performance.

  14. The arrow of electromagnetic time and the generalized absorber theory

    NASA Astrophysics Data System (ADS)

    Cramer, John G.

    1983-09-01

    The problem of the direction of electromagnetic time, i.e., the complete dominance of retarded electromagnetic radiation over advanced radiation in the universe, is considered in the context of a generalized form of the Wheeler-Feynman absorber theory in an open expanding universe with a singularity at T=0. It is shown that the application of a four-vector reflection boundary condition at the singularity leads to the observed dominance of retarded radiation; it also clarifies the role of advanced and retarded waves in the emission of very weakly absorbed radiation such as neutrinos.

  15. Electromagnetic wave energy conversion research

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  16. A high frequency analysis of electromagnetic plane wave scattering by perfectly-conducting semi-infinite parallel plate and rectangular waveguides with absorber coated inner walls

    NASA Technical Reports Server (NTRS)

    Noh, H. M.; Pathak, P. H.

    1986-01-01

    An approximate but sufficiently accurate high frequency solution which combines the uniform geometrical theory of diffraction (UTD) and the aperture integration (AI) method is developed for analyzing the problem of electromagnetic (EM) plane wave scattering by an open-ended, perfectly-conducting, semi-infinite hollow rectangular waveguide (or duct) with a thin, uniform layer of lossy or absorbing material on its inner wall, and with a planar termination inside. In addition, a high frequency solution for the EM scattering by a two dimensional (2-D), semi-infinite parallel plate waveguide with a absorber coating on the inner walls is also developed as a first step before analyzing the open-ended semi-infinite three dimensional (3-D) rectangular waveguide geometry. The total field scattered by the semi-infinite waveguide consists firstly of the fields scattered from the edges of the aperture at the open-end, and secondly of the fields which are coupled into the waveguide from the open-end and then reflected back from the interior termination to radiate out of the open-end. The first contribution to the scattered field can be found directly via the UTD ray method. The second contribution is found via the AI method which employs rays to describe the fields in the aperture that arrive there after reflecting from the interior termination. It is assumed that the direction of the incident plane wave and the direction of observation lie well inside the forward half space tht exists outside the half space containing the semi-infinite waveguide geometry. Also, the medium exterior to the waveguide is assumed to be free space.

  17. "Hearing" Electromagnetic Waves

    ERIC Educational Resources Information Center

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  18. Expanded graphite/Novolac phenolic resin composite as single layer electromagnetic wave absorber for x-band applications

    NASA Astrophysics Data System (ADS)

    Gogoi, Jyoti P.; Bhattacharyya, Nidhi Saxena

    2013-01-01

    Expanded graphite/novolac phenolic resin (EG/NPR) composites are developed as dielectric absorbers with 4mm thickness and its microwave absorption ability studied in the frequency range 8.4 to 12.4 GHz. A high reflection loss ~ -43 dB is observed at 12.4 GHz for 5 wt. % EG/NPR composites. With the increase in EG concentration in the composite the reflection loss decreases and the absorption peak shifts towards lower frequency. 7 wt. %, 8 wt. % and 10 wt. % composites shows a 10dB absorption bandwidth of order of 1GHz. Light weight EG/NPR composite shows potential to be used as cost-effective broadband microwave absorber over the X-band.

  19. Study on the electromagnetic properties of a coated radar absorbent

    NASA Astrophysics Data System (ADS)

    Zhang, Shuan-Qin

    2012-06-01

    The sol-gel method is used to fabricate Fe crystalline powders coated with SiO2. By controlling the molar ratio R of diluted water to tetraethoxysilane (TEOS), Fe powders coated with SiO2 with different morphological characteristics are fabricated. The influence of the core diameter on electromagnetic parameters is investigated. The effect of the amount of the coating material SiO2 on electromagnetic parameters is given. Radar wave absorbing properties of Fe coated with SiO2 and TiO2 respectively are compared.

  20. Electromagnetic radiation absorbers and modulators comprising polyaniline

    DOEpatents

    Epstein, Arthur J.; Ginder, John M.; Roe, Mitchell G.; Hajiseyedjavadi, Hamid

    1992-01-01

    A composition for absorbing electromagnetic radiation, wherein said electromagnetic radiation possesses a wavelength generally in the range of from about 1000 Angstroms to about 50 meters, wherein said composition comprises a polyaniline composition of the formula ##STR1## where y can be equal to or greater than zero, and R.sup.1 and R.sup.2 are independently selected from the group containing of H, --OCH.sub.3, --CH.sub.3, --F, --Cl, --Br, --I, NR.sup.3 .sub.2, --NHCOR.sup.3, --OH, --O.sup.-, SR.sup.3, --OCOR.sup.3, --NO.sub.2, --COOH, --COOR.sup.3, --COR.sup.3, --CHO, and --CN, where R.sup.3 is a C.sub.1 to C.sub.8 alkyl, aryl or aralkyl group.

  1. Recent developments of smart electromagnetic absorbers based polymer-composites at gigahertz frequencies

    NASA Astrophysics Data System (ADS)

    Idris, Fadzidah Mohd.; Hashim, Mansor; Abbas, Zulkifly; Ismail, Ismayadi; Nazlan, Rodziah; Ibrahim, Idza Riati

    2016-05-01

    The rapid increase in electromagnetic interference has received a serious attention from researchers who responded by producing a variety of radar absorbing materials especially at high gigahertz frequencies. Ongoing investigation is being carried out in order to find the best absorbing materials which can fulfill the requirements for smart absorbing materials which are lightweight, broad bandwidth absorption, stronger absorption etc. Thus, to improve the absorbing capability, several important parameters need to be taken into consideration such as filler type, loading level, type of polymer matrix, physical thickness, grain sizes, layers and bandwidth. Therefore, this article introduces the electromagnetic wave absorption mechanisms and then reveals and reviews those parameters that enhance the absorption performance.

  2. On the Huygens absorbing boundary conditions for electromagnetics

    SciTech Connect

    Berenger, Jean-Pierre

    2007-09-10

    A new absorbing boundary condition (ABC) is presented for the solution of Maxwell equations in unbounded spaces. Called the Huygens ABC, this condition is a generalization of two previously published ABCs, namely the multiple absorbing surfaces (MAS) and the re-radiating boundary condition (rRBC). The properties of the Huygens ABC are derived theoretically in continuous spaces and in the finite-difference (FDTD) discretized space. A solution is proposed to render the Huygens ABC effective for the absorption of evanescent waves. Numerical experiments with the FDTD method show that the effectiveness of the Huygens ABC is close to that of the PML ABC in some realistic problems of numerical electromagnetics. It is also shown in the paper that a combination of the Huygens ABC with the PML ABC is very well suited to the solution of some particular problems.

  3. Electromagnetic Counterparts to Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Kasliwal, Mansi M.; GROWTH Collaboration; iPTF/ZTF Collaboration

    2017-01-01

    The direct detection of gravitational waves from merging black holes marks the dawn of a new era. I will present ongoing efforts and prospectsto identify and characterize the electromagnetic counterpart. Among the various models for electromagnetic emission from binary neutronstar mergers, free neutron decay gives the most luminous and fast-evolving optical counterpart. I will describe a co-ordinated global effort, the GROWTH (Global Relay of Observatories Watching Transients Happen) network working in tandem with the Zwicky Transient Facility.

  4. Millimeter Waves: Acoustic and Electromagnetic

    PubMed Central

    Ziskin, Marvin C.

    2012-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. PMID:22926874

  5. Millimeter waves: acoustic and electromagnetic.

    PubMed

    Ziskin, Marvin C

    2013-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects.

  6. Genetic Effects of Electromagnetic Waves

    NASA Astrophysics Data System (ADS)

    Aroutiounian, Rouben; Hovhannisyan, Galina; Gasparian, Gennady

    The genetic effects of electromagnetic waves can be detected by different test-systems. The mutagenic effect of ionizing radiation can be developed on the levels of DNA and/or chromosomes. In numerous researches efficiency of micronucleus assay, alkaline single-cell gel electrophoresis, chromosomal aberrations test and FISH-technique and their different combinations for the detection of ionizing radiation-induced genotoxic effects are discussed. Also some molecular-biological approaches developed in the last years are presented.

  7. Electromagnetic transduction of ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Passarelli, Frank; Alers, George; Alers, Ron

    2012-05-01

    Excitation and detection of ultrasonic vibrations without physical contact has proven to be of great commercial value. First used to excite the resonant vibration of bar shaped laboratory specimens in the 1930's, it was Bruce Thompson's contributions in 1973-5 that launched their practical application to a wide range of difficult NDE problems. As a fresh PhD, he championed the use of mathematical models for the electromagnetic transduction process in order to guide the design and construction of practical transducers. His early papers presented both theoretical and experimental results that exposed the wide range of wave types that could be generated along with the environmental conditions that could be overcome. Several laboratories around the world established research programs to apply the electromagnetic transducer (EMAT) to specific NDE problems. This paper will summarize those applications made by the authors.

  8. Nonlocal theory of electromagnetic wave decay into two electromagnetic waves in a rippled density plasma channel

    SciTech Connect

    Sati, Priti; Tripathi, V. K.

    2012-12-15

    Parametric decay of a large amplitude electromagnetic wave into two electromagnetic modes in a rippled density plasma channel is investigated. The channel is taken to possess step density profile besides a density ripple of axial wave vector. The density ripple accounts for the momentum mismatch between the interacting waves and facilitates nonlinear coupling. For a given pump wave frequency, the requisite ripple wave number varies only a little w.r.t. the frequency of the low frequency decay wave. The radial localization of electromagnetic wave reduces the growth rate of the parametric instability. The growth rate decreases with the frequency of low frequency electromagnetic wave.

  9. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  10. Electromagnetic wave in a relativistic magnetized plasma

    SciTech Connect

    Krasovitskiy, V. B.

    2009-12-15

    Results are presented from a theoretical investigation of the dispersion properties of a relativistic plasma in which an electromagnetic wave propagates along an external magnetic field. The dielectric tensor in integral form is simplified by separating its imaginary and real parts. A dispersion relation for an electromagnetic wave is obtained that makes it possible to analyze the dispersion and collisionless damping of electromagnetic perturbations over a broad parameter range for both nonrelativistic and ultrarelativistic plasmas.

  11. Efficient transformer for electromagnetic waves

    DOEpatents

    Miller, R.B.

    A transformer structure for efficient transfer of electromagnetic energy from a transmission line to an unmatched load provides voltage multiplication and current division by a predetermined constant. Impedance levels are transformed by the square of that constant. The structure includes a wave splitter, connected to an input transmission device and to a plurality of output transmission devices. The output transmission devices are effectively connected in parallel to the input transmission device. The output transmission devices are effectively series connected to provide energy to a load. The transformer structure is particularly effective in increasing efficiency of energy transfer through an inverting convolute structure by capturing and transferring energy losses from the inverter to the load.

  12. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

    1983-08-26

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  13. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

    1985-01-01

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  14. Electromagnetic propagation in PEC and absorbing curved S-ducts

    NASA Technical Reports Server (NTRS)

    Baumeister, Kenneth J.

    1988-01-01

    A finite-element Galerkin formulation has been developed to study transverse magnetic (TM) wave propagation in 2-D S-curved ducts with both perfectly conducting and absorbing walls. The reflection and transmission at the entrances and the exits of the curved ducts are determined by coupling the finite-element solutions in the curved ducts to the eigenfunctions of an infinite, uniform, perfectly conducting duct. Example solutions are presented for a double mitred and S-ducts of various lengths. The length of the S-duct is found to significantly effect the reflective characteristics of the duct. Also, the effect of curvature on an absorbing duct is illustrated.

  15. Electromagnetic Counterparts of Gravitational Wave Transients

    NASA Astrophysics Data System (ADS)

    Branchesi, Marica

    2015-03-01

    In the near future the ground-based gravitational wave detectors will reach sensitivities that should make it possible for the first time to directly observe gravitational waves. The simultaneous availability of gravitational wave detectors observing together with space and ground-based electromagnetic telescopes will offer a great opportunity to explore the Universe in a new multi-messenger perspective. Promising sources of gravitational waves are the most energetic astrophysical events such as the merger of neutron stars and/or stellar-mass black holes and the core collapse of massive stars. These events are believed to produce electromagnetic transients in the sky, like gamma-ray bursts and supernovae. An overview of the expected electromagnetic counterparts of the gravitational wave sources is presented, focusing on the challenges, opportunities and strategies for starting transient gravitational wave astronomy.

  16. Damping and scattering of electromagnetic waves by small ferrite spheres suspended in an insulator

    NASA Technical Reports Server (NTRS)

    Englert, Gerald W.

    1992-01-01

    The intentional degradation of electromagnetic waves by their penetration into a media comprised of somewhat sparsely distributed energy absorbing ferrite spheres suspended in an electrical insulator is investigated. Results are presented in terms of generalized parameters involving wave length and sphere size, sphere resistivity, permeability, and spacing; their influence on dissipation of wave power by eddy currents, magnetic hysteresis, and scattering is shown.

  17. Magnesiothermic reduction of rice husk ash for electromagnetic wave adsorption

    NASA Astrophysics Data System (ADS)

    Liu, Shu-Ting; Yan, Kang-kang; Zhang, Yuan hu; Jin, Shi-di; Ye, Ying; Chen, Xue-Gang

    2015-11-01

    The increase in electromagnetic pollution due to the extensive exploitation of electromagnetic (EM) waves in modern technology creates correspondingly urgent need for developing effective EM wave absorbers. In this study, we carried out the magnesiothermic reduced the rice husk ash under different temperatures (400-800 °C) and investigated the electromagnetic wave adsorption of the products. The EM absorbing for all samples are mainly depend on the dielectric loss, which is ascribed to the carbon and silicon carbide content. RA samples (raw rice husk ashed in air and was magesiothermic reduced in different temperatures) exhibit poor dielectric properties, whereas RN samples (raw rice husk ashed in nitrogen and was magesiothermic reduced in different temperatures) with higher content of carbon and silicon carbide display considerable higher dielectric loss values and broader bandwidth for RL<-5 dB and -10 dB. For RN samples, the maximum bandwidth for -5 dB and -10 dB decrease with carbon contents, while the optimum thickness decrease with increasing SiC content. The optimum thickness of RN400-800 for EM absorption is 1.5-2.0 mm, with maximum RL of between -28.9 and -68.4 dB, bandwidth of 6.7-13 GHz for RL<-5 dB and 3.2-6.2 GHz for RL<-10 dB. The magnesiothermic reduction will enhance the potential application of rice husk ash in EM wave absorption and the samples benefited from low bulk density and low thickness. With the advantages of light-weight, high EM wave absorption, low cost, RN400-800 could be promising candidates for light-weight EM wave absorption materials over many conventional EM wave absorbers.

  18. Wave based optimization of distributed vibration absorbers

    NASA Astrophysics Data System (ADS)

    Johnson, Marty; Batton, Brad

    2005-09-01

    The concept of distributed vibration absorbers or DVAs has been investigated in recent years as a method of vibration control and sound radiation control for large flexible structures. These devices are comprised of a distributed compliant layer with a distributed mass layer. When such a device is placed onto a structure it forms a sandwich panel configuration with a very soft core. With this configuration the main effect of the DVA is to create forces normal to the surface of the structure and can be used at low frequencies to either add damping, where constrain layer damper treatments are not very effective, or to pin the structure over a narrow frequency bandwidth (i.e., large input impedance/vibration absorber approach). This paper analyses the behavior of these devices using a wave based approach and finds an optimal damping level for the control of broadband disturbances in panels. The optimal design is calculated by solving the differential equations for waves propagating in coupled plates. It is shown that the optimal damping calculated using the infinite case acts as a good ``rule of thumb'' for designing DVAs to control the vibration of finite panels. This is bourn out in both numerical simulations and experiments.

  19. Wave energy extraction by coupled resonant absorbers.

    PubMed

    Evans, D V; Porter, R

    2012-01-28

    In this article, a range of problems and theories will be introduced that will build towards a new wave energy converter (WEC) concept, with the acronym 'ROTA' standing for resonant over-topping absorber. First, classical results for wave power absorption for WECs constrained to operate in a single degree of freedom will be reviewed and the role of resonance in their operation highlighted. Emphasis will then be placed on how the introduction of further resonances can improve power take-off characteristics by extending the range of frequencies over which the efficiency is close to a theoretical maximum. Methods for doing this in different types of WECs will be demonstrated. Coupled resonant absorbers achieve this by connecting a WEC device equipped with its own resonance (determined from a hydrodynamic analysis) to a new system having separate mass/spring/damper characteristics. It is shown that a coupled resonant effect can be realized by inserting a water tank into a WEC, and this idea forms the basis of the ROTA device. In essence, the idea is to exploit the coupling between the natural sloshing frequencies of the water in the internal tank and the natural resonance of a submerged buoyant circular cylinder device that is tethered to the sea floor, allowing a rotary motion about its axis of attachment.

  20. Electromagnetic resonances of wavelength-selective solar absorbers with film-coupled fishnet gratings

    NASA Astrophysics Data System (ADS)

    Matsuno, Yuki; Sakurai, Atsushi

    2017-02-01

    The purpose of this study is to clarify the optical characteristics of a Tungsten-SiO2-based film-coupled metamaterial with a fishnet-shaped grating, and we aim to show that this structure could potentially be used as a solar selective absorber for a solar thermophotovoltaic system. The proposed film-coupled metamaterial absorber combined with a fishnet-shaped grating shows significant enhancement in its absorption in the visible spectral region compared with a flat Tungsten surface, and it keeps its spectral emission low in the infrared region, thereby reducing radiative heat loss. The underlying mechanisms of the proposed absorber are discussed through a 3D full-wave electromagnetic simulation, the results of which are compared with that of theoretical equations. Furthermore, its spectral absorption under oblique incident light at the transverse magnetic and transverse electric waves is scrutinized. The underlying absorption mechanisms and relations between each optical resonance are discussed in this paper and will prove to be fundamental not only in the design of solar selective absorbers but also in other wavelength-selective thermal radiation controlling devices.

  1. Scattering of electromagnetic wave by vortex flow

    NASA Astrophysics Data System (ADS)

    Wei, Jian-Ye; Liu, Jing-Yu; Mahmood, Waqas; Zhao, Qing

    2017-04-01

    In this paper, the scattering behaviour of an electromagnetic wave by vortex flow is studied in detail by solving the first-order (in v / c) Maxwell's equation in the cylindrical coordinate system (r, φ, z) and the general solutions are obtained. From these solutions, the differential cross-section of the vortex flow is calculated and the electromagnetic scattering characteristics of the vortex flow are discussed. The dependence of differential cross-section on the velocity profile and the radius of the vortex flow is investigated independently. Besides, by considering the dependence of scattering characteristics on the frequency of an incident wave we conclude that the vortex flow has frequency selectivity.

  2. Realizing thin electromagnetic absorbers for wide incidence angles from commercially available planar circuit materials

    SciTech Connect

    Glover, Brian B; Whites, Kieth W; Radway, Matthew J

    2009-01-01

    In this study, recent work on engineering R-card surface resistivity with printed metallic patterns is extended to the design of thin electromagnetic absorbers. Thin electromagnetic absorbers for wide incidence angles and both polarizations have recently been computationally verified by Luukkonen et al.. These absorbers are analytically modeled high-impedance surfaces with capacitive arrays of square patches implemented with relatively high dielectric constant and high loss substrate. However, the advantages provided by the accurate analytical model are largely negated by the need to obtain high dielectric constant material with accurately engineered loss. Fig. I(c) illustrates full-wave computational results for an absorber without vias engineered as proposed by Luukkonen et al.. Unique values for the dielectric loss are required for different center frequencies. Parameters for the capacitive grid are D=5.0 mm and w=O.l mm for a center frequency of 3.36 GHz. The relative permittivity and thickness is 9.20(1-j0.234) and 1=3.048 mm. Consider a center frequency of5.81 GHz and again 1=3.048 mm, the required parameters for the capacitive grid are D=2.0 mm and w=0.2 mm where the required relative permittivity is now 9.20(1-j0.371) Admittedly, engineered dielectrics are themselves a historically interesting and fruitful research area which benefits today from advances in monolithic fabrication using direct-write of dielectrics with nanometer scale inclusions. However, our objective in the present study is to realize the advantages of the absorber proposed by Luukkonen et al. without resort to engineered lossy dielectrics. Specifically we are restricted to commercially available planer circuit materials without use of in-house direct-write technology or materials engineering capability. The materials considered here are TMM 10 laminate with (35 {mu}lm copper cladding with a complex permittivity 9.20-j0.0022) and Ohmegaply resistor conductor material (maximum 250 {Omega

  3. Responses of Waveform-Selective Absorbing Metasurfaces to Oblique Waves at the Same Frequency

    NASA Astrophysics Data System (ADS)

    Wakatsuchi, Hiroki; Gao, Fei; Yagitani, Satoshi; Sievenpiper, Daniel F.

    2016-08-01

    Conventional materials vary their electromagnetic properties in response to the frequency of an incoming wave, but these responses generally remain unchanged at the same frequency unless nonlinearity is involved. Waveform-selective metasurfaces, recently developed by integrating several circuit elements with planar subwavelength periodic structures, allowed us to distinguish different waves even at the same frequency depending on how long the waves continued, namely, on their pulse widths. These materials were thus expected to give us an additional degree of freedom to control electromagnetic waves. However, all the past studies were demonstrated with waves at a normal angle only, although in reality electromagnetic waves scatter from various structures or boundaries and therefore illuminate the metasurfaces at oblique angles. Here we study angular dependences of waveform-selective metasurfaces both numerically and experimentally. We demonstrate that, if designed properly, capacitor-based waveform-selective metasurfaces more effectively absorb short pulses than continuous waves (CWs) for a wide range of the incident angle, while inductor-based metasurfaces absorb CWs more strongly. Our study is expected to be usefully exploited for applying the concept of waveform selectivity to a wide range of existing microwave devices to expand their functionalities or performances in response to pulse width as a new capability.

  4. Responses of Waveform-Selective Absorbing Metasurfaces to Oblique Waves at the Same Frequency.

    PubMed

    Wakatsuchi, Hiroki; Gao, Fei; Yagitani, Satoshi; Sievenpiper, Daniel F

    2016-08-12

    Conventional materials vary their electromagnetic properties in response to the frequency of an incoming wave, but these responses generally remain unchanged at the same frequency unless nonlinearity is involved. Waveform-selective metasurfaces, recently developed by integrating several circuit elements with planar subwavelength periodic structures, allowed us to distinguish different waves even at the same frequency depending on how long the waves continued, namely, on their pulse widths. These materials were thus expected to give us an additional degree of freedom to control electromagnetic waves. However, all the past studies were demonstrated with waves at a normal angle only, although in reality electromagnetic waves scatter from various structures or boundaries and therefore illuminate the metasurfaces at oblique angles. Here we study angular dependences of waveform-selective metasurfaces both numerically and experimentally. We demonstrate that, if designed properly, capacitor-based waveform-selective metasurfaces more effectively absorb short pulses than continuous waves (CWs) for a wide range of the incident angle, while inductor-based metasurfaces absorb CWs more strongly. Our study is expected to be usefully exploited for applying the concept of waveform selectivity to a wide range of existing microwave devices to expand their functionalities or performances in response to pulse width as a new capability.

  5. Responses of Waveform-Selective Absorbing Metasurfaces to Oblique Waves at the Same Frequency

    PubMed Central

    Wakatsuchi, Hiroki; Gao, Fei; Yagitani, Satoshi; Sievenpiper, Daniel F.

    2016-01-01

    Conventional materials vary their electromagnetic properties in response to the frequency of an incoming wave, but these responses generally remain unchanged at the same frequency unless nonlinearity is involved. Waveform-selective metasurfaces, recently developed by integrating several circuit elements with planar subwavelength periodic structures, allowed us to distinguish different waves even at the same frequency depending on how long the waves continued, namely, on their pulse widths. These materials were thus expected to give us an additional degree of freedom to control electromagnetic waves. However, all the past studies were demonstrated with waves at a normal angle only, although in reality electromagnetic waves scatter from various structures or boundaries and therefore illuminate the metasurfaces at oblique angles. Here we study angular dependences of waveform-selective metasurfaces both numerically and experimentally. We demonstrate that, if designed properly, capacitor-based waveform-selective metasurfaces more effectively absorb short pulses than continuous waves (CWs) for a wide range of the incident angle, while inductor-based metasurfaces absorb CWs more strongly. Our study is expected to be usefully exploited for applying the concept of waveform selectivity to a wide range of existing microwave devices to expand their functionalities or performances in response to pulse width as a new capability. PMID:27516346

  6. Improvement of Electromagnetic Wave Absorption Ability by Reducing Impedance Oscillation Characteristics

    NASA Astrophysics Data System (ADS)

    Itoh, Masahiro; Terada, Masao; Sasada, Masaaki; Machida, Ken-ichi

    2012-01-01

    Improvement of the electromagnetic wave absorption ability was examined from the electromagnetic point of view. The oscillation behavior in relation to incident impedance derived from a hyperbolic tangent function can be reduced by increasing the imaginary part, i.e., loss value, of permeability and/or permittivity owing to its mathematical characteristics. It was demonstrated that the electromagnetic wave absorption ability was obviously enhanced by inserting the lossy magnetic layer between the electromagnetic wave absorber and a reflector. The absorption ability was improved further by pilling the polyurethane foam plate having lower permittivity to provide -9.6 dB (ca. 89% absorption) for the frequency range above 0.75 GHz with a total absorber thickness of 15.15 mm.

  7. Emergent cosmological constant from colliding electromagnetic waves

    SciTech Connect

    Halilsoy, M.; Mazharimousavi, S. Habib; Gurtug, O. E-mail: habib.mazhari@emu.edu.tr

    2014-11-01

    In this study we advocate the view that the cosmological constant is of electromagnetic (em) origin, which can be generated from the collision of em shock waves coupled with gravitational shock waves. The wave profiles that participate in the collision have different amplitudes. It is shown that, circular polarization with equal amplitude waves does not generate cosmological constant. We also prove that the generation of the cosmological constant is related to the linear polarization. The addition of cross polarization generates no cosmological constant. Depending on the value of the wave amplitudes, the generated cosmological constant can be positive or negative. We show additionally that, the collision of nonlinear em waves in a particular class of Born-Infeld theory also yields a cosmological constant.

  8. Fundamental research on oscillating water column wave power absorbers

    SciTech Connect

    Maeda, H.; Kato, W.; Kinoshita, T.; Masuda, K.

    1985-03-01

    An oscillating water column (OWC) wave power absorber is one of the most promising devices, as well as the Salter Duck and the Clam. This paper presents a simple prediction method, in which the equivalent floating body approximation is used, for absorbing wave power characteristics of an oscillating water column device. The effects of the compressibility of air and inertia of an air turbine and electric generator on absorbed wave power are obtained by using the equivalent electric circuit concept. Both the experimental and theoretical studies are carried out in this paper.

  9. Global Simulation of Electromagnetic Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K.; Gallagher, D. L.; Kozyra, J. U.

    2007-01-01

    It is well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. [2002 - 2007]. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis

  10. Global Simulation of Electromagnetic Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Gallagher, D. L.; Kozyra, J. U.

    2007-01-01

    It is very well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis of modern

  11. Global Simulation of Electromagnetic Ion Cyclotron Waves

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2007-12-01

    It is well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. [2002 - 2007]. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis

  12. Electromagnetic waves in a strong Schwarzschild plasma

    SciTech Connect

    Daniel, J.; Tajima, T.

    1996-11-01

    The physics of high frequency electromagnetic waves in a general relativistic plasma with the Schwarzschild metric is studied. Based on the 3 + 1 formalism, we conformalize Maxwell`s equations. The derived dispersion relations for waves in the plasma contain the lapse function in the plasma parameters such as in the plasma frequency and cyclotron frequency, but otherwise look {open_quotes}flat.{close_quotes} Because of this property this formulation is ideal for nonlinear self-consistent particle (PIC) simulation. Some of the physical consequences arising from the general relativistic lapse function as well as from the effects specific to the plasma background distribution (such as density and magnetic field) give rise to nonuniform wave equations and their associated phenomena, such as wave resonance, cutoff, and mode-conversion. These phenomena are expected to characterize the spectroscopy of radiation emitted by the plasma around the black hole. PIC simulation results of electron-positron plasma are also presented.

  13. Study on coupled shock absorber system using four electromagnetic dampers

    NASA Astrophysics Data System (ADS)

    Fukumori, Y.; Hayashi, R.; Okano, H.; Suda, Y.; Nakano, K.

    2016-09-01

    Recently, the electromagnetic damper, which is composed of an electric motor, a ball screw, and a nut, was proposed. The electromagnetic damper has high responsiveness, controllability, and energy saving performance. It has been reported that it improved ride comfort and drivability. In addition, the authors have proposed a coupling method of two electromagnetic dampers. The method enables the characteristics of bouncing and rolling or pitching motion of a vehicle to be tuned independently. In this study, the authors increase the number of coupling of electromagnetic dampers from two to four, and propose a method to couple four electromagnetic dampers. The proposed method enables the characteristics of bouncing, rolling and pitching motion of a vehicle to be tuned independently. Basic experiments using proposed circuit and motors and numerical simulations of an automobile equipped with the proposed coupling electromagnetic damper are carried out. The results indicate the proposed method is effective.

  14. High-performance terahertz wave absorbers made of silicon-based metamaterials

    SciTech Connect

    Yin, Sheng; Zhu, Jianfei; Jiang, Wei; Yuan, Jun; Yin, Ge; Ma, Yungui; Xu, Wendao; Xie, Lijuan; Ying, Yibin

    2015-08-17

    Electromagnetic (EM) wave absorbers with high efficiency in different frequency bands have been extensively investigated for various applications. In this paper, we propose an ultra-broadband and polarization-insensitive terahertz metamaterial absorber based on a patterned lossy silicon substrate. Experimentally, a large absorption efficiency more than 95% in a frequency range of 0.9–2.5 THz was obtained up to a wave incident angle as large as 70°. Much broader absorption bandwidth and excellent oblique incidence absorption performance are numerically demonstrated. The underlying mechanisms due to the combination of a waveguide cavity mode and impedance-matched diffraction are analyzed in terms of the field patterns and the scattering features. The monolithic THz absorber proposed here may find important applications in EM energy harvesting systems such as THz barometer or biosensor.

  15. Selective Pyroelectric Detection of Millimetre Waves Using Ultra-Thin Metasurface Absorbers

    PubMed Central

    Kuznetsov, Sergei A.; Paulish, Andrey G.; Navarro-Cía, Miguel; Arzhannikov, Andrey V.

    2016-01-01

    Sensing infrared radiation is done inexpensively with pyroelectric detectors that generate a temporary voltage when they are heated by the incident infrared radiation. Unfortunately the performance of these detectors deteriorates for longer wavelengths, leaving the detection of, for instance, millimetre-wave radiation to expensive approaches. We propose here a simple and effective method to enhance pyroelectric detection of the millimetre-wave radiation by combining a compact commercial infrared pyro-sensor with a metasurface-enabled ultra-thin absorber, which provides spectrally- and polarization-discriminated response and is 136 times thinner than the operating wavelength. It is demonstrated that, due to the small thickness and therefore the thermal capacity of the absorber, the detector keeps the high response speed and sensitivity to millimetre waves as the original infrared pyro-sensor does against the regime of infrared detection. An in-depth electromagnetic analysis of the ultra-thin resonant absorbers along with their complex characterization by a BWO-spectroscopy technique is presented. Built upon this initial study, integrated metasurface absorber pyroelectric sensors are implemented and tested experimentally, showing high sensitivity and very fast response to millimetre-wave radiation. The proposed approach paves the way for creating highly-efficient inexpensive compact sensors for spectro-polarimetric applications in the millimetre-wave and terahertz bands. PMID:26879250

  16. Selective Pyroelectric Detection of Millimetre Waves Using Ultra-Thin Metasurface Absorbers

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Sergei A.; Paulish, Andrey G.; Navarro-Cía, Miguel; Arzhannikov, Andrey V.

    2016-02-01

    Sensing infrared radiation is done inexpensively with pyroelectric detectors that generate a temporary voltage when they are heated by the incident infrared radiation. Unfortunately the performance of these detectors deteriorates for longer wavelengths, leaving the detection of, for instance, millimetre-wave radiation to expensive approaches. We propose here a simple and effective method to enhance pyroelectric detection of the millimetre-wave radiation by combining a compact commercial infrared pyro-sensor with a metasurface-enabled ultra-thin absorber, which provides spectrally- and polarization-discriminated response and is 136 times thinner than the operating wavelength. It is demonstrated that, due to the small thickness and therefore the thermal capacity of the absorber, the detector keeps the high response speed and sensitivity to millimetre waves as the original infrared pyro-sensor does against the regime of infrared detection. An in-depth electromagnetic analysis of the ultra-thin resonant absorbers along with their complex characterization by a BWO-spectroscopy technique is presented. Built upon this initial study, integrated metasurface absorber pyroelectric sensors are implemented and tested experimentally, showing high sensitivity and very fast response to millimetre-wave radiation. The proposed approach paves the way for creating highly-efficient inexpensive compact sensors for spectro-polarimetric applications in the millimetre-wave and terahertz bands.

  17. Numerical wave tank based on a conserved wave-absorbing method

    NASA Astrophysics Data System (ADS)

    Hu, Zhe; Tang, Wen-yong; Xue, Hong-xiang; Zhang, Xiao-ying

    2016-03-01

    Recently the numerical wave tank has become a widely-used tool to study waves as well as wave-structure interactions, and the wave-absorbing method is very important as its effect on the quality of waves generated. The relaxation method and the derived momentum source method are often utilized, however, the damping weight is constant during calculation and repeated trials are required to obtain an acceptable wave-absorbing effect. To address the abovementioned issues, a conserved wave-absorbing method is developed. The damping weight is determined by solving the mass conservation equation of the absorbing region at every time step. Based on this method, a two-dimensional numerical wave tank is established by using the VB language to simulate various waves by which the validation of this method is evaluated.

  18. Understanding possible electromagnetic counterparts to loud gravitational wave events: Binary black hole effects on electromagnetic fields

    SciTech Connect

    Palenzuela, Carlos; Lehner, Luis; Yoshida, Shin

    2010-04-15

    In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

  19. Nonmagnetic metamaterial landscapes for guided electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Viaene, S.; Ginis, V.; Danckaert, J.; Tassin, P.

    2016-09-01

    Transformation optics provides a geometry-based tool to create new components taking advantage of artificial metamaterials with optical properties that are not available in nature. Unfortunately, although guided electromagnetic waves are crucial for optical circuitry, transformation optics is not yet compatible with two-dimensional slab waveguides. Indeed, after determining the propagation of confined waves along the waveguide with a two-dimensional coordinate transformation, the conventional application of transformation optics results in metamaterials whose properties are insensitive to the coordinate perpendicular to the waveguide, leading to bulky, and therefore impractical, designs. In this contribution, we formulate an alternative framework that leads to feasible coordinate-based designs of two-dimensional waveguides. To this end, we characterize a guided transverse-magnetic light mode by relevant electromagnetic equations: a Helmholtz equation to account for wave propagation and a dispersion relation to impose a continuous light profile at the interface. By considering how two-dimensional conformal transformations transform these equations, we are able to materialize the coordinate-designed flows with a nonmagnetic metamaterial core of varying thickness, obtaining a two-dimensional device. We numerically demonstrate the effectiveness and versatility of our equivalence relations with three crucial functionalities, a beam bender, a beam splitter and a conformal lens, on a qualitative and quantitative level, by respectively comparing the electromagnetic fields inside and the transmission of our two-dimensional metamaterial devices to that of their three-dimensional counterparts at telecom wavelengths. As a result, we envision that one coordinate-based multifunctional waveguide component may seamlessly split and bend light beams on the landscape of an optical chip.

  20. Interface Polarization Strategy to Solve Electromagnetic Wave Interference Issue.

    PubMed

    Lv, Hualiang; Guo, Yuhang; Wu, Guanglei; Ji, Guangbin; Zhao, Yue; Xu, Zhichuan J

    2017-02-15

    Design of an interface to arouse interface polarization is an efficient route to attenuate high-frequency electromagnetic waves. The attenuation intensity is highly related to the contact area. To achieve stronger interface polarization, growing metal oxide granular film on graphene with a larger surface area seems to be an efficient strategy due to the high charge carrier concentration of graphene. This study is devoted to fabricating the filmlike composite by a facile thermal decomposition method and investigating the relationship among contact area, polarization intensity, and the type of metal oxide. Because of the high-frequency polarization effect, the composites presented excellent electromagnetic wave attenuation ability. It is shown that the optimal effective frequency bandwidth of graphene/metal oxide was close to 7.0 GHz at a thin coating layer of 2.0 mm. The corresponding reflection loss value was nearly -22.1 dB. Considering the attenuation mechanism, interface polarization may play a key role in the microwave-absorbing ability.

  1. Electromagnetic Propagationg of Waves in Helical Stochastic

    NASA Astrophysics Data System (ADS)

    Adrian, Reyes; Mendez, David

    2012-02-01

    We develop a model for studying the axial propagation of elliptically polarized electromagnetic waves in a spatially random helical media. We start by writing Maxwell equations for a structurally chiral medium whose helical angle contains both a stochastic contribution and a deterministic one, this latter corresponding to an uniform rotation. We write the electromagnetic equations into Marcuvitz Schwigner representation to transform them afterward by using the Oseen transformation. We exhibit that in the Oseen frame, Marcuvitz Schwigner equations turns out to be a linear vectorial stochastic system of equations with multiplicative noise. From this result and utilizing a well known formalism for treating stochastic differential equations, we find the governing equations for the first and second moments of the field amplitudes for a general correlation model for the slope angles, and calculate their corresponding band structure for a particular spectral noise density. We show that the average resulting electromagnetic fields exhibit dissipation and the appearance of a new reflection band whose chirality is the opposite of the one obtained for a simple cholesteric liquid crystals.

  2. Design of electromagnetic shock absorbers for automotive suspensions

    NASA Astrophysics Data System (ADS)

    Amati, Nicola; Festini, Andrea; Tonoli, Andrea

    2011-12-01

    Electromechanical dampers seem to be a valid alternative to conventional shock absorbers for automotive suspensions. They are based on linear or rotative electric motors. If they are of the DC-brushless type, the shock absorber can be devised by shunting its electric terminals with a resistive load. The damping force can be modified by acting on the added resistance. To supply the required damping force without exceeding in size and weight, a mechanical or hydraulic system that amplifies the speed is required. This paper illustrates the modelling and design of such electromechanical shock absorbers. This paper is devoted to describe an integrated design procedure of the electrical and mechanical parameters with the objective of optimising the device performance. The application to a C class front suspension car has shown promising results in terms of size, weight and performance.

  3. Electromagnetic wave structures within subauroral polarization streams

    NASA Astrophysics Data System (ADS)

    Mishin, E. V.; Burke, W. J.; Huang, C. Y.; Rich, F. J.

    2003-08-01

    We report on oscillations in electric (δEY) and magnetic (δBZ) fields and plasma density (δNi) observed by Defense Meteorological Satellite Program (DMSP) satellites within fast subauroral convection streams in the evening sector during the magnetic storm of 6 November 2001. There are two types of wave phenomena. The first and more common is characterized by electromagnetic and plasma density variations that have the same frequency range of ˜0.15 Hz in the spacecraft frame of reference. The second is characterized by large-amplitude plasma and field oscillations over a broader range of frequencies ˜0.1 to 0.3 Hz. In this case the perturbation densities and fields appear to have different frequency responses. In this and other magnetic storms, strong waves are associated with the precipitation of ˜30 keV ions. Ratios of δEY/δBZ indicate encounters with mixtures of electromagnetic (in part Alfvénic) and electrostatic modes. Poynting vectors associated with the oscillations can be directed either into or out of the ionosphere. The density perturbations appear to be extended east-west corrugations in the plasma flow streams with north-south wavelengths of ˜50 km. The δEY and δNi variations were anticorrelated, as required for current conservation. Our analysis shows that Alfvénic perturbations are consistent with expected effects of irregular potential distribution around ionospheric density irregularities mapped to the magnetosphere. Inertial currents act to generate mesoscale field-aligned currents carried by Alfvén waves, as was previously discussed with regards to auroral arcs formation. We suggest that δNi irregularities observed by DMSP satellites in the evening sector began as striated plasma patches in the polar cap that convected to subauroral latitudes.

  4. High latitude electromagnetic plasma wave emissions

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  5. Plasma wave aided two photon decay of an electromagnetic wave in a plasma

    SciTech Connect

    Kumar, K. K. Magesh; Singh, Rohtash; Krishan, Vinod

    2014-11-15

    The presence of a Langmuir wave in an unmagnetized plasma is shown to allow parametric decay of an electromagnetic wave into two electromagnetic waves, which is otherwise not allowed due to wave number mismatch. The decay occurs at plasma densities below one ninth the critical density and the decay waves propagate at finite angles to the pump laser. Above the threshold, the growth rate scales linearly with the amplitude of the Langmuir wave and the amplitude of the pump electromagnetic wave. The frequency ω of the lower frequency decay wave increases with the angle its propagation vector makes with that of the pump. The growth rate, however, decreases with ω.

  6. Electromagnetic and microwave-absorbing properties of magnetic nickel ferrite nanocrystals.

    PubMed

    Zhu, Weimo; Wang, Lei; Zhao, Rui; Ren, Jiawen; Lu, Guanzhong; Wang, Yanqin

    2011-07-01

    The electromagnetic and microwave absorbing properties of nickel ferrite nanocrystals were investigated for the first time. There were two frequencies corresponding to the maximum reflection loss in a wide thickness range from 3.0 to 5.0 mm, which may be bought by the nanosize effect and the good crystallization of the nanocrystals.

  7. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium

    PubMed Central

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-01-01

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066

  8. Design of Metamaterials for control of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Koschny, Thomas

    2014-03-01

    Metamaterials are artificial effective media supporting propagating waves that derive their properties form the average response of deliberately designed and arranged, usually resonant scatterers with structural length-scales much smaller than the wavelength inside the material. Electromagnetic metamaterials are the most important implementation of metamaterials, which are made from deeply sub-wavelength electric, magnetic and chiral resonators and can be designed to work from radio frequencies all the way to visible light. Metamaterials have been major new development in physics and materials science over the last decade and are still attracting more interest as they enable us to create materials with unique properties like negative refraction, flat and super lenses, impedance matching eliminating reflection, perfect absorbers, deeply sub-wavelength sized wave guides and cavities, tunability, enhanced non-linearity and gain, chirality and huge optical activity, control of Casimir forces, and spontaneous emission, etc. In this talk, I will discuss the design, numerical simulation, and mathematical modeling of metamaterials. I will survey the current state of the art and discuss challenges, possible solutions and perspectives. In particular, the problem of dissipative loss and their possible compensation by incorporating spatially distributed gain in metamaterials. If the gain sub-system is strongly coupled to the sub-wavelength resonators of the metamaterial loss compensation and undamping of the resonant response of the metamaterials can occur. I will explore new, alternative dielectric low loss resonators for metamaterials as well as the potential of new conducting materials such as Graphene to replace metals as the conducting material in resonant metamaterials. Two dimensional metamaterials or metasurfaces, implementations of effective electromagnetic current sheets in which both electric and magnetic sheet conductivities are controlled by the average response

  9. Electromagnetic waves: Negative refraction by photonic crystals

    NASA Astrophysics Data System (ADS)

    Ozbay, Ekmel

    2004-03-01

    Recently left-handed materials (LHM) attracted great attention since these materials exhibit negative effective index, which is due to simultaneously negative permeability and permittivity. Pendry proposed that negative effective index in left-handed materials can be used for constructing a perfect lens, which is not limited by diffraction(J. B. Pendry, Negative refraction makes a perfect lens, Phys. Rev. Lett. vol. 85, 3966 (2000)). Negative refraction is also achievable in a dielectric photonic crystal (PC) that has a periodically modulated positive permittivity and a permeability of unity. Luo et al. has studied negative refraction and subwavelength imaging in photonic crystals(C. Luo, S. G. Johnson, J. D. Joannopoulos, J. B. Pendry, Subwavelength Imaging in Photonic Crystals Phys. Rev. B 68, 045115 (2003)). In this presentation, we report our experimental and theoretical investigation of negative refraction and subwavelength focusing of electromagnetic waves in a 2D PC. Our structure consists of a square array of dielectric rods in air. Transmission measurements are performed for experimentally verifying the predicted negative refraction behavior in our structure. Negative index of refraction determined from the experiment is -1.94 which is very close to the theoretical value of -2.06. Negative refraction is observed for the incidence angles of > 20°(Ertugrul Cubukcu, Koray Aydin, Ekmel Ozbay, S. Foteinopolou, and Costas Soukoulis, Negative Refraction by Photonic Crystals, Nature, vol. 423, 604 (2003)). Since we know the optimum frequency for a broad angle negative refraction, we can use our crystal to test the superlensing effect that was predicted for negative refractive materials. Scanning transmission measurement technique is used to measure the spatial power distribution of the focused electromagnetic waves that radiate from a point source. Full width at half maximum of the focused beam is measured to be 0.21λ, which is in good agreement with the finite

  10. A hybrid electromagnetic shock absorber for active vehicle suspension systems

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Babak; Bolandhemmat, Hamidreza; Behrad Khamesee, Mir; Golnaraghi, Farid

    2011-02-01

    The use of electromagnetic dampers (ED) in vehicle active suspension systems has drawn considerable attention in the past few years, attributed to the fact that active suspension systems have shown superior performance in improving ride comfort and road handling of terrain vehicles, compared with their passive and semi-active counterparts. Although demonstrating superb performance, active suspensions still have some shortcomings that must be overcome. They have high energy consumption, weight, and cost and are not fail-safe in case of a power breakdown. The novel hybrid ED, which is proposed in this paper, is a potential solution to the above-mentioned drawbacks of conventional active suspension systems. The proposed hybrid ED is designed to inherit the high-performance characteristics of an active ED with the reliability of a passive damper in a single package. The eddy current damping effect is utilised as a source of the passive damping. First, a prototype ED is designed and fabricated. The prototype ED is then utilised to experimentally establish the design requirements for a real-size active ED. This is accomplished by comparing its vibration isolation performance in a 1-DOF quarter-car test rig with that of a same-class semi-active damper. Then, after a real-size active ED is designed, the concept of hybrid damper is introduced to the damper design to address the drawbacks of the active ED. Finally, the finite-element method is used to accurately model and analyse the designed hybrid damper. It is demonstrated that by introducing the eddy current damping effect to the active part, a passive damping of approximately 1570 Ns/m is achieved. This amount of passive damping guarantees that the damper is fail-safe and reduces the power consumption more than 70%, compared with an active ED in an automotive active suspension system.

  11. Electromagnetic and microwave absorbing properties of carbonyl iron/BaTiO3 composite absorber for matched load of isolator

    NASA Astrophysics Data System (ADS)

    Ren, Xiaohu; Cheng, Yankui

    2015-11-01

    Composite absorbers made from carbonyl iron powder and BaTiO3 were prepared by blending technique with the matrix of epoxy resin. The structure and microtopography of the carbonyl iron and BaTiO3 particles were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructure and electromagnetic properties of the as-prepared composites were investigated by SEM and vector network analyzer (VNA). The effect of the mass ratio of BaTiO3/carbonyl iron on the electromagnetic properties of the composites is investigated. The bandwidth with an absorption loss exceeding 30 dB is obtained in the whole measured frequency range for all composites, and an optimal reflection loss drop below 1.5 dB with 24 wt% BaTiO3. It is found that the carbonyl iron/BaTiO3 composite absorber can be a promising candidate as a matched load for the isolator.

  12. Electromagnetic drift waves dispersion for arbitrarily collisional plasmas

    SciTech Connect

    Lee, Wonjae Krasheninnikov, Sergei I.; Angus, J. R.

    2015-07-15

    The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionless and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.

  13. Multiple Scattering of Electromagnetic Waves in Discrete Random Media.

    DTIC Science & Technology

    1984-12-31

    purposes, we have also investigated the electromagnetic wave propagation through randomly distributed and oriented scatterers by introducing the concept...computer to determine whether or not particle overlap has occurred. The implementation of the "physics" of the system and orientations of non-spherical...34Coherent electromagnetic wave propagation through randomly distributed and oriented pair-correlated dielectric scatterers," Radio Sci., 19, 1445-1449

  14. Wireless device for activation of an underground shock wave absorber

    NASA Astrophysics Data System (ADS)

    Chikhradze, M.; Akhvlediani, I.; Bochorishvili, N.; Mataradze, E.

    2011-10-01

    The paper describes the mechanism and design of the wireless device for activation of energy absorber for localization of blast energy in underground openings. The statistics shows that the greatest share of accidents with fatal results associate with explosions in coal mines due to aero-methane and/or air-coal media explosion. The other significant problem is terrorist or accidental explosions in underground structures. At present there are different protective systems to reduce the blast energy. One of the main parts of protective Systems is blast Identification and Registration Module. The works conducted at G. Tsulukidze Mining Institute of Georgia enabled to construct the wireless system of explosion detection and mitigation of shock waves. The system is based on the constant control on overpressure. The experimental research continues to fulfill the system based on both threats, on the constant control on overpressure and flame parameters, especially in underground structures and coal mines. Reaching the threshold value of any of those parameters, the system immediately starts the activation. The absorber contains a pyrotechnic device ensuring the discharge of dispersed water. The operational parameters of wireless device and activation mechanisms of pyrotechnic element of shock wave absorber are discussed in the paper.

  15. Surface electromagnetic wave equations in a warm magnetized quantum plasma

    SciTech Connect

    Li, Chunhua; Yang, Weihong; Wu, Zhengwei; Chu, Paul K.

    2014-07-15

    Based on the single-fluid plasma model, a theoretical investigation of surface electromagnetic waves in a warm quantum magnetized inhomogeneous plasma is presented. The surface electromagnetic waves are assumed to propagate on the plane between a vacuum and a warm quantum magnetized plasma. The quantum magnetohydrodynamic model includes quantum diffraction effect (Bohm potential), and quantum statistical pressure is used to derive the new dispersion relation of surface electromagnetic waves. And the general dispersion relation is analyzed in some special cases of interest. It is shown that surface plasma oscillations can be propagated due to quantum effects, and the propagation velocity is enhanced. Furthermore, the external magnetic field has a significant effect on surface wave's dispersion equation. Our work should be of a useful tool for investigating the physical characteristic of surface waves and physical properties of the bounded quantum plasmas.

  16. Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range.

    PubMed

    González, M; Crespo, M; Baselga, J; Pozuelo, J

    2016-05-19

    Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials.

  17. A robust absorbing layer method for anisotropic seismic wave modeling

    SciTech Connect

    Métivier, L.; Brossier, R.; Labbé, S.; Operto, S.; Virieux, J.

    2014-12-15

    When applied to wave propagation modeling in anisotropic media, Perfectly Matched Layers (PML) exhibit instabilities. Incoming waves are amplified instead of being absorbed. Overcoming this difficulty is crucial as in many seismic imaging applications, accounting accurately for the subsurface anisotropy is mandatory. In this study, we present the SMART layer method as an alternative to PML approach. This method is based on the decomposition of the wavefield into components propagating inward and outward the domain of interest. Only outgoing components are damped. We show that for elastic and acoustic wave propagation in Transverse Isotropic media, the SMART layer is unconditionally dissipative: no amplification of the wavefield is possible. The SMART layers are not perfectly matched, therefore less accurate than conventional PML. However, a reasonable increase of the layer size yields an accuracy similar to PML. Finally, we illustrate that the selective damping strategy on which is based the SMART method can prevent the generation of spurious S-waves by embedding the source in a small zone where only S-waves are damped.

  18. An Apparatus for Constructing an Electromagnetic Plane Wave Model

    ERIC Educational Resources Information Center

    Kneubil, Fabiana Botelho; Loures, Marcus Vinicius Russo; Amado, William

    2015-01-01

    In this paper we report on an activity aimed at building an electromagnetic wave. This was part of a class on the concept of mass offered to a group of 20 pre-service Brazilian physics teachers. The activity consisted of building a plane wave using an apparatus in which it is possible to fit some rods representing electric and magnetic fields into…

  19. Polarization ray picture of coherence for vectorial electromagnetic waves

    SciTech Connect

    Luis, Alfredo

    2007-10-15

    We elucidate a ray picture of coherence for vectorial electromagnetic waves by using the Stokes parameters for light rays defined by the optical Wigner function. Paraxial propagation is formulated as a complementary Huygens principle. We show that the degrees of coherence are averages of the phase difference where the weights are the Stokes parameters for light rays. We analyze the van Cittert-Zernike theorem for vectorial waves in terms of ray propagation. We show that simple polarization measurements in a Young interferometer determine the degrees of coherence for vectorial electromagnetic waves.

  20. Interaction of electromagnetic wave with quantum over dense plasma layer

    NASA Astrophysics Data System (ADS)

    Rajaei, Leila

    2016-10-01

    The anomalous transmission of electromagnetic wave in the cold over dense plasma is investigated using the quantum hydrodynamic approach. The quantum effect on the dispersion relation of the surface wave excited by the electromagnetic radiation is evaluated and compared with the classical regimes. It is shown that the quantum dispersion curve, in comparison with its classical behavior, has an asymptotic approach at larger wave numbers. Investigating the transmission conditions, the effects of the main different parameters of the model such as the plasma density and Fermi velocity on the rate of transmission are scrutinized.

  1. Electron acceleration in the ionosphere by obliquely propagating electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Burke, William J.; Ginet, Gregory P.; Heinemann, Michael A.; Villalon, Elena

    The paper presents an analysis of the relativistic equations of motion for electrons in magnetized plasma and externally imposed electromagnetic fields that propagate at arbitrary angles to the background magnetic field. The relativistic Lorentz equation for a test electron moving under the influence of an electromagnetic wave in a cold magnetized plasma and wave propagation through the ionospheric 'radio window' are examined. It is found that at wave energy fluxes greater than 10 to the 8th mW/sq m, initially cold electrons can be accelerated to energies of several MeV in less than a millisecond. Plans to test the theoretical results with rocket flights are discussed.

  2. Transition operators in electromagnetic-wave diffraction theory - General theory

    NASA Technical Reports Server (NTRS)

    Hahne, G. E.

    1992-01-01

    A formal theory is developed for the scattering of time-harmonic electromagnetic waves from impenetrable immobile obstacles with given linear, homogeneous, and generally nonlocal boundary conditions of Leontovich (impedance) type for the wave of the obstacle's surface. The theory is modeled on the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. An expression for the differential scattering cross section for plane electromagnetic waves is derived in terms of certain matrix elements of the T operator for the obstacle.

  3. Radiative transfer effects on reflected shock waves. II - Absorbing gas.

    NASA Technical Reports Server (NTRS)

    Su, F. Y.; Olfe, D. B.

    1972-01-01

    Radiative cooling effects behind a reflected shock wave are calculated for an absorbing-emitting gas by means of an expansion procedure in the small density ratio across the shock front. For a gray gas shock layer with an optical thickness of order unity or less the absorption integral is simplified by use of the local temperature approximation, whereas for larger optical thicknesses a Rosseland diffusion type of solution is matched with the local temperature approximation solution. The calculations show that the shock wave will attenuate at first and then accelerate to a constant velocity. Under appropriate conditions the gas enthalpy near the wall may increase at intermediate times before ultimately decreasing to zero. A two-band absorption model yields end-wall radiant-heat fluxes which agree well with available shock-tube measurements.

  4. Wideband long wave infrared metamaterial absorbers based on silicon nitride

    NASA Astrophysics Data System (ADS)

    Üstün, Kadir; Turhan-Sayan, Gönül

    2016-11-01

    In this paper, we present silicon nitride metamaterial absorber designs that accomplish large bandwidth and high absorption in the long wave infrared (LWIR) region. These designs are based on the metal-insulator-metal topology, insulator (silicon nitride), and the top metal (aluminum) layers are optimized to obtain high absorptance values in large bandwidths, for three different silicon nitride based absorber structures. The absorption spectrum of the final design reaches absorptance values above 90% in the wavelength interval between 8.07 μm and 11.97 μm, and above 80% in the wavelength interval between 7.9 μm and 14 μm, in the case of normal incidence. The difficulty in the design process of such absorbers stems from the highly dispersive behavior of silicon nitride in the LWIR region. On the other hand, silicon nitride is a widely used material in microbolometers, and accomplishing wide band absorption in silicon nitride is crucial in this regard. Therefore, this study will pave the way for more efficient infrared imaging devices, which are crucial for defense and security systems. Additionally, such designs may also find applications in thermal emitters.

  5. Manipulating surface plasmon waves by transformation optics: Design examples of a beam squeezer, bend, and omnidirectional absorber

    NASA Astrophysics Data System (ADS)

    Yu, Zhen-Zhong; Feng, Yi-Jun; Wang, Zheng-Bin; Zhao, Jun-Ming; Jiang, Tian

    2013-03-01

    We present several design examples of how to apply transformation optics and curved space under coordinate transformation to manipulating the surface plasmon waves in a controlled manner. We demonstrate in detail the design procedure of the plasmonic wave squeezer, in-plane bend and omnidirectional absorber. We show that the approximation method of modifying only the dielectric material of a dielectric-metal surface of the plasmonic device could lead to acceptable performance, which facilitates the fabrication of the device. The functionality of the proposed plasmonic device is verified using three-dimensional full-wave electromagnetic simulations. Aiming at practical realization, we also show the design of a plasmonic in-plane bend and omnidirectional absorber by an alternative transformation scheme, which results in a simple device structure with a tapered isotropic dielectric cladding layer on the top of the metal surface that can be fabricated with existing nanotechnology.

  6. Relativistic electromagnetic waves in an electron-ion plasma

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.; Kennel, Charles F.

    1987-01-01

    High power laser beams can drive plasma particles to relativistic energies. An accurate description of strong waves requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic waves in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the wave velocity, the wave amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic waves and electrostatic plasma waves are used as illustrations.

  7. Microstructural diagnosis using electromagnetic wave scattering methodologies

    NASA Astrophysics Data System (ADS)

    Chou, Kevin Jenn Chien

    Scattered electromagnetic waves were used in the present work to characterize the microstructural effects on the performance of metallic materials. A Nisb3Al alloy with a dendritic microstructure has exhibited better creep resistance compared to similar alloys having equiaxed microstructure of grains. X-ray diffraction was applied along the dendritic arms to investigate their orientations. Both the interlocking boundaries and crystallographic texture of the dendritic arms resulted in the superior creep behavior. Non-invasive laser scattering was also used to optically probe smooth fatigue specimens to detect and monitor the development of fatigue damage. Inconel 718 specimens with a cylindrical geometry were tested under low cycle fatigue conditions with constant strain amplitudes ranging from 0.3% to 1%. A detection scheme to minimize computational time and memory was used to achieve in-situ data analysis. Both laser scanning and surface replication procedures were periodically performed throughout the life of the specimens. The scattered light signals were compared with microcrack length and density data from surface replicate SEM images. Three characteristic stages of the scattering signal were observed. The scanning laser light scattering (SLLS) technique was sufficiently robust, and well suited for the non-planar geometry in the leading edge. The SLLS signals correlated well with microstructural features over a large surface area. A physical model of microcrack size distribution within a surface grain was developed. The results of the model suggest that a SLLS signal saturation which coincides with the onset of microcrack density saturation corresponds to a transition from predominately single grain microcracks to microcracks that transverse multiple grains. The saturation of SLLS signal versus mean surface crack length also provided the following findings. Low cycle fatigue cracks were contained and saturated in those surface grains with the highest Schmid

  8. Electromagnetic wave absorption properties of composites with ultrafine hollow magnetic fibers

    NASA Astrophysics Data System (ADS)

    Yi, Jin Woo; Lee, Sang Bok; Kim, Jin Bong; Lee, Sang Kwan; Park, O. Ok

    2014-06-01

    Ultrafine hollow magnetic fibers were prepared by electroless plating using hydrolyzed polyester fiber as a sacrificial substrate. These hollow fibers can be served for lightweight and efficient electromagnetic (EM) absorbing materials. As observed from SEM and EDS analysis, hollow structures consisting of Ni inner layer and Fe or Fe-Co outer layer were obtained. By introducing Co onto Fe, oxidation of the Fe layer was successfully prevented making it possible to enhance the complex permeability compared to a case in which only Fe was used. Polymeric composites containing the hollow fibers with different weight fractions and fiber lengths were prepared by a simple mixing process. The electromagnetic wave properties of the composites were measured by a vector network analyzer and it was found that the hollow magnetic fibers show a clear resonance peak of the complex permittivity around the X-band range (8-12 GHz) and the resonance frequency strongly depends on the fiber concentration and length. A possible explanation for the unique resonance is that the hollow fibers possess relatively low electrical conductivity and a long mean free path due to their oxidized phase and hollow structure. The calculated EM wave absorption with the measured EM wave properties showed that the composite containing 30 wt% hollow Ni/Fe-Co (7:3) fibers in length of 180 μm exhibited multiple absorbance peaks resulting in a broad absorption bandwidth of 4.2 GHz. It is obvious that this multiple absorbance is attributed to the resonance characteristic of the composite.

  9. Nonlinear decay of electromagnetic ion cyclotron waves in the magnetosphere

    SciTech Connect

    Gomberoff, L.; Gratton, F.T.; Gnavi, G.

    1995-02-01

    The authors study the parametric decays of left-hand polarized electromagnetic ion cyclotron waves, propagating parallel to the external magnetic field, in the magnetosphere. They show that the presence of He{sup +} ions and a mixed population of thermal and hot protons give rise to new wave couplings. These couplings lead to a number of new instabilities. Some of the instabilities involve sound waves carried mainly by the He{sup +} ions, which can be very efficient in heating up the bulk of the He{sup +} ions via Landau damping. Other instabilities involve the branch of the left-hand polarized electromagnetic ion cyclotron waves which has a resonance at the He{sup +} ion gyrofrequency. These instabilities can also play a role in the energy transfer from the pump wave to the He{sup +} ions through resonance absorption, preferably in the direction perpendicular to the external magnetic field. The new couplings give rise to several types of parametric instabilities such as ordinary decay instabilities, beat wave instabilities, and modulational instabilities. There are also couplings where the pump wave decays into the two electromagnetic sideband waves. 42 refs., 10 figs.

  10. A time domain energy theorem for scattering of plane electromagnetic waves

    NASA Astrophysics Data System (ADS)

    de Hoop, A. T.

    1984-10-01

    A time domain analysis of the scattering problem reveals the more general conditions under which the relevant theorems in the theory of the scattering of electromagnetic waves by an obstacle of bounded extent may also hold in the time domain. The present investigation is concerned with the energy theorem for plane wave scattering. Three different kinds of time behavior are considered, taking into account transient fields, time-periodic fields, and perpetuating fields. The derived energy theorem relates the energy which is both absorbed and scattered by the object to the spherical-wave amplitude of the scattered field in the far-field region, when observed in the direction of propagation of the incident plane wave.

  11. A metasurface carpet cloak for electromagnetic, acoustic and water waves.

    PubMed

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-29

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.

  12. Left-handed interfaces for electromagnetic surface waves.

    PubMed

    Kats, A V; Savel'ev, Sergey; Yampol'skii, V A; Nori, Franco

    2007-02-16

    We show that surface electromagnetic waves (SEMWs) propagating along two-dimensional (2D) interfaces separating different metamaterials can behave analogously to 3D electromagnetic waves in either usual or left-handed media, depending on the permeabilities and/or permittivities of the two materials forming the interface. We derive the conditions when SEMWs carry energy opposite to the phase velocity. In analogy to three-dimensional (3D) left-handed media, we derive both an anomalous Cherenkov emission and a reversed Doppler effect. We also predict a negative refraction at the boundary between two different interfaces, which can be useful for perfect 2D lensing.

  13. A universal electromagnetic energy conversion adapter based on a metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

    2014-09-01

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor.

  14. A universal electromagnetic energy conversion adapter based on a metamaterial absorber

    PubMed Central

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

    2014-01-01

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor. PMID:25200005

  15. A universal electromagnetic energy conversion adapter based on a metamaterial absorber.

    PubMed

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D; Simons, Rainee N; Chen, Yunpeng; Xiao, John Q

    2014-09-09

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor.

  16. Cooling systems and hybrid A/C systems using an electromagnetic radiation-absorbing complex

    DOEpatents

    Halas, Nancy J.; Nordlander, Peter; Neumann, Oara

    2015-05-19

    A method for powering a cooling unit. The method including applying electromagnetic (EM) radiation to a complex, where the complex absorbs the EM radiation to generate heat, transforming, using the heat generated by the complex, a fluid to vapor, and sending the vapor from the vessel to a turbine coupled to a generator by a shaft, where the vapor causes the turbine to rotate, which turns the shaft and causes the generator to generate the electric power, wherein the electric powers supplements the power needed to power the cooling unit

  17. Electromagnetic waves and Stokes parameters in the wake of a gravitational wave

    NASA Astrophysics Data System (ADS)

    Hacyan, Shahen

    2012-11-01

    A theoretical description of electromagnetic waves in the background of a (weak) gravitational wave is presented. Explicit expressions are obtained for the Stokes parameters during the passage of a plane-fronted gravitational wave described by the Ehlers-Kundt metric. In particular, it is shown that the axis of the polarization ellipse oscillates, its ellipticity remaining constant.

  18. Study of a condition for the mode conversion from purely perpendicular electrostatic waves to electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Kalaee, Mohammad Javad; Katoh, Yuto

    2016-07-01

    One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma waves (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.

  19. Reduced Graphene Oxide Functionalized with Cobalt Ferrite Nanocomposites for Enhanced Efficient and Lightweight Electromagnetic Wave Absorption

    PubMed Central

    Ding, Yi; Liao, Qingliang; Liu, Shuo; Guo, Huijing; Sun, Yihui; Zhang, Guangjie; Zhang, Yue

    2016-01-01

    In this paper, reduced graphene oxide functionalized with cobalt ferrite nanocomposites (CoFe@rGO) as a novel type of electromagnetic wave (EW) absorbing materials was successfully prepared by a three-step chemical method including hydrothermal synthesis, annealing process and mixing with paraffin. The effect of the sample thickness and the amount of paraffin on the EW absorption properties of the composites was studied, revealing that the absorption peaks shifted toward the low frequency regions with the increasing thickness while other conditions had little or no effect. It is found that the CoFe@rGO enhanced both dielectric losses and magnetic losses and had the best EW absorption properties and the wide wavelength coverage of the hole Ku-Band when adding only 5wt% composites to paraffin. Therefore, CoFe@rGO could be used as an efficient and lightweight EW absorber. Compared with the research into traditional absorbing materials, this figures of merit are typically of the same order of magnitude, but given the lightweight nature of the material and the high level of compatibility with mass production standards, making use of CoFe@rGO as an electromagnetic absorber material shows great potential for real product applications. PMID:27587001

  20. Electromagnetic rogue waves in beam-plasma interactions

    NASA Astrophysics Data System (ADS)

    Veldes, G. P.; Borhanian, J.; McKerr, M.; Saxena, V.; Frantzeskakis, D. J.; Kourakis, I.

    2013-06-01

    The occurrence of rogue waves (freak waves) associated with electromagnetic pulse propagation interacting with a plasma is investigated, from first principles. A multiscale technique is employed to solve the fluid Maxwell equations describing weakly nonlinear circularly polarized electromagnetic pulses in magnetized plasmas. A nonlinear Schrödinger (NLS) type equation is shown to govern the amplitude of the vector potential. A set of non-stationary envelope solutions of the NLS equation are considered as potential candidates for the modeling of rogue waves (freak waves) in beam-plasma interactions, namely in the form of the Peregrine soliton, the Akhmediev breather and the Kuznetsov-Ma breather. The variation of the structural properties of the latter structures with relevant plasma parameters is investigated, in particular focusing on the ratio between the (magnetic field dependent) cyclotron (gyro-)frequency and the plasma frequency.

  1. Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas

    SciTech Connect

    Masood, Waqas; Eliasson, Bengt; Shukla, Padma K.

    2010-06-15

    A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin-(1/2), and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin-(1/2) contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars.

  2. Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas.

    PubMed

    Masood, Waqas; Eliasson, Bengt; Shukla, Padma K

    2010-06-01

    A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin- 1/2, and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin- 1/2 contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars.

  3. Response of thermal ions to electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Fuselier, S. A.

    1994-01-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  4. Response of thermal ions to electromagnetic ion cyclotron waves

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Fuselier, S. A.

    1994-10-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  5. Electromagnetic resonances of solar-selective absorbers with nanoparticle arrays embedded in a dielectric layer

    NASA Astrophysics Data System (ADS)

    Sakurai, Atsushi; Kawamata, Tomoaki

    2016-11-01

    We numerically investigate a solar-selective absorber with tungsten core-shell nanoparticle arrays embedded in an SiO2 layer. The 3D full-wave finite-difference time-domain (FDTD) simulations are performed to investigate the geometric effects of different types of solar-selective absorbers. Consequently, broadband light absorption was achieved with either a tungsten nanoparticle array or a tungsten core-shell nanoparticle array because of the strong electric field enhancement in the gap between the core nanoparticles. The solar performance of the proposed structure is shown for high-efficiency solar light absorption. This study enhances understanding of the light absorption mechanism of metallic nanoparticle/dielectric composite and facilitates the design of high-efficiency solar-selective absorbers.

  6. Molding acoustic, electromagnetic and water waves with a single cloak

    PubMed Central

    Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien

    2015-01-01

    We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. PMID:26057934

  7. Fractional Cylindrical Functions Implementation for Electromagnetic Waves Scattering Analysis

    DTIC Science & Technology

    2002-09-01

    IMPLEMENTATION FOR ELECTROMAGNETIC WAVES SCATTERING ANALYSIS D.V. Golovin , D.O. Batrakov. Kharkov National University, Ukraine Dmitry.O.Batrakov...N2 8. P. 1483. [2] Vorontsov A.A., Mirovitskaya S.D/I Radiotechnika i Electronika (in Russian) 1986. V.31. No 12. P. 2330. [3] Golovin D.V., Batrakov

  8. Double absorbing boundaries for finite-difference time-domain electromagnetics

    NASA Astrophysics Data System (ADS)

    LaGrone, John; Hagstrom, Thomas

    2016-12-01

    We describe the implementation of optimal local radiation boundary condition sequences for second order finite difference approximations to Maxwell's equations and the scalar wave equation using the double absorbing boundary formulation. Numerical experiments are presented which demonstrate that the design accuracy of the boundary conditions is achieved and, for comparable effort, exceeds that of a convolution perfectly matched layer with reasonably chosen parameters. An advantage of the proposed approach is that parameters can be chosen using an accurate a priori error bound.

  9. Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves

    SciTech Connect

    Fan, Ren-Hao; Peng, Ru-Wen; Huang, Xian-Rong; Wang, Mu

    2015-07-15

    In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertz ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies. - Highlights: • Making structured metals transparent for ultrabroadband electromagnetic waves. • Non-resonant excitation of surface plasmons or spoof surface plasmons. • Sonic artificially metallic structures transparent for broadband acoustic waves.

  10. Transition of electromagnetic wave by suddenly created magneto plasma

    NASA Astrophysics Data System (ADS)

    Kuo, Spencer P.

    2017-02-01

    The theory of the interaction of electromagnetic waves with a suddenly created magneto plasma is presented. It is shown that a linearly polarized wave propagating along the magnetic field is converted into a frequency upshifted two forward and two backward propagating waves; in each propagation direction, one is right hand circular polarization and the other one is left hand circular polarization. A static wiggler magnetic field is also produced. The combined forward and backward waves are amplitude modulated with rotating polarizations. The extent of the frequency upshift increases with the increases of the plasma density and the background magnetic field intensity. By increasing the background magnetic field, the required plasma density for the frequency upshift is reduced; consequently, the drop rate of the conversion efficiency with the increase in the frequency upshift of the combined forward wave can be reduced considerably; the conversion efficiency of the combined backward wave also increases.

  11. Co/graphite based light weight microwave absorber for electromagnetic shielding and stealth applications

    NASA Astrophysics Data System (ADS)

    Ansari, Azizurrahaman; Jaleel Akhtar, Mohammad

    2017-01-01

    The magnetic, thermal, thermo-mechanical, electromagnetic and microwave absorption properties of Co/graphite loaded polystyrene composites prepared by melt blending and injection molding techniques are studied in X-band (8.4–12.4 GHz) for seeking their usage as efficient light weight microwave absorbers. For profound understanding of electromagnetic absorption process at micro level, the advanced SEM and x-ray diffraction testing of the composites are carried out. The magnetic properties of the prepared Co/graphite loaded polystyrene composites are studied using the vibrating sample magnetometer. The thermal stability and thermo-mechanical properties of the prepared composites are analyzed by thermo gravimetric analysis and dynamic mechanical and thermal analysis, respectively. The complex permittivity and permeability values of the prepared composite samples in X-band of microwave frequency are extracted from the scattering data recorded during the vector network analyzer measurements. The minimum reflection loss (maximum absorption loss) of  ‑32.02 dB (99.94%) is achieved at 10.13 GHz for Co/graphite loaded polystyrene composite with the excess loading of graphite flakes for sample thickness of 1.8 mm. High absorption loss, light weight and low thickness of the proposed multicomponent Co/graphite loaded polystyrene composites make them promising candidates for electromagnetic shielding and stealth applications.

  12. Nonlinear Self-Similar Beams of Electromagnetic Waves in Vacuum

    NASA Astrophysics Data System (ADS)

    Vlasov, S. N.

    2015-12-01

    We study nonlinear beams of electromagnetic waves in vacuum. Within the lowest approximation, their structure is determined by the cubic self-focusing nonlinearity, which manifests itself with the maximum intensity in the presence of counterpropagating waves. It is shown that the fields in the beams have no singularities if their power is less than the critical power of the self-focusing. The dependences of the eigenfrequencies of the modes of the quasioptical resonator on the beam power are found. The structure of the fields of these modes corresponds to self-similar wave beams.

  13. Reflection and interference of electromagnetic waves in inhomogeneous media

    NASA Technical Reports Server (NTRS)

    Geiger, F. E.; Kyle, H. L.

    1973-01-01

    Solutions were obtained of the wave equation for a plane horizontally polarized electro-magnetic wave incident on a semi infinite two dimensional inhomogeneous medium. Two problems were considered: An inhomogeneous half space, and an inhomogeneous layer of arbitrary thickness. Solutions of the wave equation were obtained in terms of Hankel functions with complex arguments. Numerical calculations were made of the reflection coefficient R at the interface of the homogeneous medium. The startling results show that the reflection coefficient for a complex dielectric constant with gradient, can be less than that of the same medium with zero gradient.

  14. Electromagnetic Waves Broadcast by a VCR.

    ERIC Educational Resources Information Center

    Brown, Michael H.

    1996-01-01

    Presents experiments that use a video cassette recorder (VCR) to demonstrate polarization of radio waves using two dipole antennas and a spark gap transmitter tuned to a frequency of either 60-66 MHz or 66-72 MHz with wavelengths of 5 or 4.3 meters, close to the wavelengths of the original work done by Heinrich Hertz. (JRH)

  15. Impact of Fog on Electromagnetic Wave Propagation

    NASA Astrophysics Data System (ADS)

    Morris, Jonathon; Fleisch, Daniel

    2002-04-01

    This experiment was designed to explore the impact of fog on electromagnetic radiation, in particular microwaves and infrared light. For years law enforcement agencies have used microwave radiation (radar guns) to measure the speed of vehicles, and the last ten years has seen increased use of LIDAR, which uses 905-nm infrared radiation rather than microwaves. To evaulate the effect of fog on the operation of these devices, we have constructed a fog chamber with microwave and optical portals to allow light from a HeNe laser and 10.6-GHz microwaves to propagate through various densities of fog. Data is acquired using Vernier Logger Pro and analyzed using MATLAB and Mathematica. Using the attenuation of the laser light to determine fog density, the impact of fog on the signal-to-noise ratio of both microwave and IR devices may be quantified, and the maximum useful range may be calculated.

  16. On the breaking of a plasma wave in a thermal plasma. II. Electromagnetic wave interaction with the breaking plasma wave

    SciTech Connect

    Bulanov, Sergei V.; Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K.; Pirozhkov, Alexander S.; Nakamura, Tatsufumi; Bulanov, Stepan S.; Schroeder, Carl B.; Esarey, Eric; Califano, Francesco; Pegoraro, Francesco

    2012-11-15

    In thermal plasma, the structure of the density singularity formed in a relativistically large amplitude plasma wave close to the wavebreaking limit leads to a refraction coefficient with discontinuous spatial derivatives. This results in a non-exponentially small above-barrier reflection of an electromagnetic wave interacting with the nonlinear plasma wave.

  17. Scattering and Depolarization of Electromagnetic Waves--Full Wave Solutions.

    DTIC Science & Technology

    1984-01-01

    Analysis," Proceedings of the International Union of Radio Science URSI Conference at Ciudad Universitaria , Madrid, August 1983, in press. . . 13...rough land and seat3 J. The full wave approach was also used to determine the scattering and depolarization of radio waves in irregular spheroidal struc...Full Wave Solutions," Radio Science, Vol. 17, No. 5, September-October 1982, pp. 1055-1066. 4. "Scattering and Depolarization by Rough Surfaces: Full

  18. A maximally informative version of inelastic scattering of electromagnetic waves by Langmuir waves

    NASA Astrophysics Data System (ADS)

    Erofeev, V. I.

    2015-09-01

    The concept of informativeness of nonlinear plasma physics scenarios is explained. Natural ideas of developing highly informative models of plasma kinetics are spelled out. A maximally informative version of inelastic scattering of electromagnetic waves by Langmuir waves in a weakly turbulent inhomogeneous plasma is developed with consideration of possible changes in wave polarization. In addition, a new formula for wave drift in spatial positions and wave vectors is derived. New scenarios of the respective wave drift and inelastic scattering are compared with the previous visions. The results indicate the need for further revision of the traditional understanding of nonlinear plasma phenomena.

  19. A maximally informative version of inelastic scattering of electromagnetic waves by Langmuir waves

    SciTech Connect

    Erofeev, V. I.

    2015-09-15

    The concept of informativeness of nonlinear plasma physics scenarios is explained. Natural ideas of developing highly informative models of plasma kinetics are spelled out. A maximally informative version of inelastic scattering of electromagnetic waves by Langmuir waves in a weakly turbulent inhomogeneous plasma is developed with consideration of possible changes in wave polarization. In addition, a new formula for wave drift in spatial positions and wave vectors is derived. New scenarios of the respective wave drift and inelastic scattering are compared with the previous visions. The results indicate the need for further revision of the traditional understanding of nonlinear plasma phenomena.

  20. Nonlinear Generation of Electromagnetic Waves Through Scattering by Thermal Electrons

    NASA Astrophysics Data System (ADS)

    Tejero, E. M.; Crabtree, C. E.; Blackwell, D. D.; Amatucci, B.; Mithaiwala, M.; Rudakov, L.; Ganguli, G.

    2014-12-01

    Nonlinear interactions involving whistler wave turbulence are important contributors to radiation belt dynamics, including the acceleration and loss of trapped electrons. Given sufficient whistler energy density, nonlinear scattering from thermal electrons can substantially change the wave normal angle, while inducing a small frequency shift [Ganguli et al., 2010]. This nonlinear process is being studied in the NRL Space Physics Simulation Chamber (SPSC) in scaled magnetospheric conditions. The plasma response as a function of transmitted lower hybrid wave amplitude is monitored with magnetic loop antennas. Measurements of the magnetic field vectors for the pump and daughter waves allow for the determination of wave distribution functions, which indicate the power distribution as a function of wave-normal angle and azimuthal angle. The wave distribution functions measured in the experiment demonstrate a dramatic change in propagation direction when the launched wave amplitude exceeds a small threshold (δB / B ~ 4 × 10-7). The experimental results support the theory of electromagnetic whistler wave generation through nonlinear scattering of electrostatic lower hybrid waves by thermal electrons in the Earth's magnetosphere [Crabtree et al, 2012].

  1. Parametric decay of an electromagnetic wave near electron cyclotron harmonics

    SciTech Connect

    Istomin, Y.N.; Leyser, T.B.

    1995-06-01

    A system of equations describing the nonlinear coupling of high frequency electron Bernstein (EB) and upper hybrid (UH) waves near harmonics of the electron cyclotron frequency with low frequency lower hybrid (LH) waves in a homogeneous, weakly magnetized, and weakly collisional plasma is derived. The EB and UH modes are described by a single second order equation, taking into account the interaction with low frequency density fluctuations. The ponderomotive force of the high frequency oscillations increases near the cyclotron harmonics due to the resonance with the electron motion. The obtained equations are used to study the parametric decay of an infinite wavelength electromagnetic pump wave into EB or UH waves and LH waves. The threshold electric fields are sufficiently low to be exceeded in high frequency ionospheric modification experiments. However, the instability cannot be excited for pump frequencies near the cyclotron harmonics. For the decay into EB waves, the resulting forbidden frequency range depends on the harmonic number in a power law manner, consistent with observations of stimulated electromagnetic emissions in ionospheric modification experiments. Further, for sufficiently high pump electric fields the instability is also suppressed, when the frequency mismatch around the eigenfrequencies at which the interaction can occur is of the order of the frequency separation between the EB and UH modes near the cyclotron harmonics. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  2. The momentum of an electromagnetic wave inside a dielectric

    SciTech Connect

    Testa, Massimo

    2013-09-15

    The problem of assigning a momentum to an electromagnetic wave packet propagating inside an insulator has become known under the name of the Abraham–Minkowski controversy. In the present paper we re-examine this issue making the hypothesis that the forces exerted on an insulator by an electromagnetic field do not distinguish between polarization and free charges. Under this assumption we show that the Abraham expression for the radiation mechanical momentum is highly favored. -- Highlights: •We discuss an approximation to treat electrodynamics of a dielectric material. •We support the Abraham form for the electromagnetic momentum. •We deduce Snell’s law from the conservation of the Abraham momentum. •We show how to deal with the electric field discontinuity at the dielectric boundary.

  3. Collision of strong gravitational and electromagnetic waves in the expanding universe

    NASA Astrophysics Data System (ADS)

    Alekseev, G. A.

    2016-03-01

    An exact analytical model of the process of collision and nonlinear interaction of gravitational and/or electromagnetic soliton waves and strong nonsoliton electromagnetic traveling waves of arbitrary profile propagating in the expanding universe (the symmetric Kasner spacetime) is presented. In contrast to intuitive expectations that rather strong traveling waves can destroy the soliton, it occurs that the soliton survives during its interaction with electromagnetic waves of arbitrary amplitude and profile, but its parameters begin to evolve under the influence of this interaction. If a traveling electromagnetic wave possesses a finite duration, the soliton parameters after interaction take constant values again, but these values in general are different from those before the interaction. Based on exact solutions of the Einstein-Maxwell equations, our model demonstrates a series of nonlinear phenomena, such as (a) creation of gravitational waves in the collision of two electromagnetic waves, (b) creation of electromagnetic soliton waves in the collision of a gravitational soliton with traveling electromagnetic waves, (c) scattering of a part of a soliton wave in the direction of propagation of a traveling electromagnetic wave, and (d) quasiperiodic oscillating character of fields in the wave interaction region and multiple mutual transformations of gravitational and electromagnetic waves in this region. The figures illustrate these features of nonlinear wave interactions in general relativity.

  4. Predicting Electromagnetic Signatures of Gravitational Wave Sources

    NASA Astrophysics Data System (ADS)

    D'Orazio, Daniel John

    This dissertation investigates the signatures of electromagnetic radiation that may accompany two specific sources of gravitational radiation: the inspiral and merger of massive black hole binaries (MBHBs) in galactic nuclei, and the coalescence of black hole neutron star (BHNS) pairs. Part I considers the interaction of MBHBs, at sub-pc separations, with a circumbinary gas disk. Accretion rates onto the MBHB are calculated from two-dimensional hydrodynamical simulations as a function of the relative masses of the black holes. The results are applied to interpretation of the recent, sub-pc separation MBHB candidate in the nucleus of the periodically variable Quasar PG 1302-102. We advance an interpretation of the variability observed in PG 1302-102 as being caused by Doppler-boosted emission sourced by the orbital velocity of the smaller black hole in a MBHB with disparate relative masses. Part II considers BHNS binaries in which the black hole is large enough to swallow the neutron star whole before it is disrupted. As the pair nears merger, orbital motion of the black hole through the magnetosphere of the neutron star generates an electromotive force, a black-hole-battery, which, for the strongest neutron star magnetic field strengths, could power luminosities large enough to make the merging pair observable out to cosmic distances. Relativistic solutions for vacuum fields of a magnetic dipole near a horizon are given, and a mechanism for harnessing the power of the black-hole-battery is put forth in the form of a fireball emitting in hard X-rays to gamma-rays.

  5. Electromagnetic scattering and depolarization across rough surfaces: Full wave analysis

    NASA Astrophysics Data System (ADS)

    Bahar, Ezekiel; Huang, Guorong; Lee, Bom Son

    1995-05-01

    Full wave solutions are derived for vertically and horizontally polarized waves diffusely scattered across an interface that is two-dimensionally rough separating two different propagating media. Since the normal to the rough surface is not restricted to the reference plane of incidence, the waves are depolarized upon scattering; and the single scattered radiation fields are expressed as integrals of a surface element transmission scattering matrix that also accounts for coupling between the vertically and horizontally polarized waves. The integrations are over the rough surface area as well as the complete two-dimensional wave spectra of the radiation fields. The full wave solutions satisfy the duality and reciprocity relationships in electromagnetic theory, and the surface element scattering matrix is invariant to coordinate transformations. It is shown that in the high-frequency limit the full wave solutions reduce to the physical optics solutions, while in the low-frequency limit (for small mean square heights and slopes) the full wave solutions reduce to Rice's (1951) small perturbation solutions. Thus, the full wave solution accounts for specular point scattering as well as diffuse, Bragg-type scattering in a unified, self-consistent manner. It is therefore not necessary to use hybrid, perturbation and physical optics approaches (based on two-scale models of composite surfaces with large and small roughness scales) to determine the like- and cross-polarized fields scattered across the rough surface.

  6. Highly Efficient Proteolysis Accelerated by Electromagnetic Waves for Peptide Mapping

    PubMed Central

    Chen, Qiwen; Liu, Ting; Chen, Gang

    2011-01-01

    Proteomics will contribute greatly to the understanding of gene functions in the post-genomic era. In proteome research, protein digestion is a key procedure prior to mass spectrometry identification. During the past decade, a variety of electromagnetic waves have been employed to accelerate proteolysis. This review focuses on the recent advances and the key strategies of these novel proteolysis approaches for digesting and identifying proteins. The subjects covered include microwave-accelerated protein digestion, infrared-assisted proteolysis, ultraviolet-enhanced protein digestion, laser-assisted proteolysis, and future prospects. It is expected that these novel proteolysis strategies accelerated by various electromagnetic waves will become powerful tools in proteome research and will find wide applications in high throughput protein digestion and identification. PMID:22379392

  7. Electromagnetic wave extinction within a forested canopy

    NASA Technical Reports Server (NTRS)

    Karam, M. A.; Fung, A. K.

    1989-01-01

    A forested canopy is modeled by a collection of randomly oriented finite-length cylinders shaded by randomly oriented and distributed disk- or needle-shaped leaves. For a plane wave exciting the forested canopy, the extinction coefficient is formulated in terms of the extinction cross sections (ECSs) in the local frame of each forest component and the Eulerian angles of orientation (used to describe the orientation of each component). The ECSs in the local frame for the finite-length cylinders used to model the branches are obtained by using the forward-scattering theorem. ECSs in the local frame for the disk- and needle-shaped leaves are obtained by the summation of the absorption and scattering cross-sections. The behavior of the extinction coefficients with the incidence angle is investigated numerically for both deciduous and coniferous forest. The dependencies of the extinction coefficients on the orientation of the leaves are illustrated numerically.

  8. Detection of Underground Tunnels with a Synchronized Electromagnetic Wave Gradiometer

    DTIC Science & Technology

    2005-05-01

    Active Auroral Research Program ( HAARP ). A synchronization receiver channel was added to the design so that the gradiometer receiver could be...testing electromagnetic systems with local or remote transmission sources. The HAARP transmitter has demonstrated the ability to modulate the...The HAARP program has studied several techniques for the detection of underground structures using ELF/VLF radio waves generated in the ionosphere. An

  9. Gradient instabilities of electromagnetic waves in Hall thruster plasma

    SciTech Connect

    Tomilin, Dmitry

    2013-04-15

    This paper presents a linear analysis of gradient plasma instabilities in Hall thrusters. The study obtains and analyzes the dispersion equation of high-frequency electromagnetic waves based on the two-fluid model of a cold plasma. The regions of parameters corresponding to unstable high frequency modes are determined and the dependence of the increments and intrinsic frequencies on plasma parameters is obtained. The obtained results agree with those of previously published studies.

  10. Minimizing the Reflection of Electromagnetic Waves by Surface Impedance.

    DTIC Science & Technology

    1986-07-01

    Chen2’ and G. Crosta3 ,** Technical Summary Report #2942 July 1986 ABSTRACT In an empty halfspace a point source emits electromagnetic waves of fixed...are determined by means of the geometrical optics approximation. An optimization method is used to compute the surface impedance, which minimizes a...given function of the e.m. fields (e.g. the average energy density) at a given observation point . The properties of the functions to be minimized are

  11. Electromagnetic waves in a model with Chern-Simons potential

    NASA Astrophysics Data System (ADS)

    Pis'mak, D. Yu.; Pis'mak, Yu. M.; Wegner, F. J.

    2015-07-01

    We investigated the appearance of Chern-Simons terms in electrodynamics at the surface or interface of materials. The requirement of locality, gauge invariance, and renormalizability in this model is imposed. Scattering and reflection of electromagnetic waves in three different homogeneous layers of media is determined. Snell's law is preserved. However, the transmission and reflection coefficient depend on the strength of the Chern-Simons interaction (connected with Hall conductance), and parallel and perpendicular components are mixed.

  12. Electromagnetic performance and microwave absorbing property of nanocrystalline Sm2Fe14B compound

    NASA Astrophysics Data System (ADS)

    Han, Rui; Yi, Hai-bo; Wei, Jian-qiang; Qiao, Liang; Wang, Tao; Li, Fa-shen

    2012-09-01

    A new planar anisotropy Sm2Fe14B nanocrystal as an electromagnetic absorption material was prepared by melt-spinning method. The electromagnetic and microwave absorbing properties of Sm2Fe14B nanocrystal/nonmagnetic matrix composite in the frequency range of 0.1-10 GHz were measured and calculated. At the perfect matching point (2.9 GHz), the minimum reflection loss reaches -42.0 dB at the matching thickness of 3.1 mm. Furthermore, the calculation shows that the normalized input impedance Z in/ Z 0 equals 1, but the modulus of the ratio between the complex permittivity and permeability | ɛ/ μ| is far away from unity at the perfect matching point. The effective permeability of the composite was simulated using the combination of the Landau-Lifshitz-Gilbert equation and Bruggeman's effective medium theory; the agreement between the experimental data and the theoretical one demonstrates that the magnetic loss in the composite is mainly caused by natural resonance.

  13. Electromagnetic ion cyclotron waves observed in the plasma depletion layer

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Fuselier, S. A.; Murr, D.

    1991-01-01

    Observations from AMPTE/CCE in the earth's magnetosheath on October 5, 1984 are presented to illustrate 0.1 - 4.0 Hz magnetic field pulsations in the subsolar plasma depletion layer (PDL) for northward sheath field during a magnetospheric compression. The PDL is unambiguously identified by comparing CCE data with data from IRM in the upstream solar wind. Pulsations in the PDL are dominated by transverse waves with F/F(H+) 1.0 or less and a slot in spectral power at F/F(H+) = 0.5. The upper branch is left hand polarized while the lower branch is linearly polarized. In the sheath the proton temperature anisotropy is about 0.6 but it is about 1.7 in the PDL during wave occurrence. The properties and correlation of waves with increased anisotropy indicate that they are electromagnetic ion cyclotron waves.

  14. Electromagnetically induced transparency of a plasmonic metamaterial light absorber based on multilayered metallic nanoparticle sheets

    PubMed Central

    Okamoto, Koichi; Tanaka, Daisuke; Degawa, Ryo; Li, Xinheng; Wang, Pangpang; Ryuzaki, Sou; Tamada, Kaoru

    2016-01-01

    In this study, we observed the peak splitting of absorption spectra for two-dimensional sheets of silver nanoparticles due to the electromagnetically induced transparency (EIT) effect. This unique optical phenomenon was observed for the multilayered nanosheets up to 20 layers on a metal substrate, while this phenomenon was not observed on a transparent substrate. The wavelength and intensities of the split peaks depend on the number of layers, and the experimental results were well reproduced by the calculation of the Transfer-Matrix method by employing the effective medium approximation. The Ag nanosheets used in this study can act as a plasmonic metamaterial light absorber, which has a such large oscillator strength. This phenomenon is a fundamental optical property of a thin film on a metal substrate but has never been observed because native materials do not have a large oscillator strength. This new type of EIT effect using a plasmonic metamaterial light absorber presents the potential for the development of future optic and photonic technologies. PMID:27824071

  15. Hydrothermal synthesis of magnetic Fe3O4/graphene composites with good electromagnetic microwave absorbing performances

    NASA Astrophysics Data System (ADS)

    Zhu, Lingyu; Zeng, Xiaojun; Li, Xiaopan; Yang, B.; Yu, Ronghai

    2017-03-01

    The Fe3O4 sub-microspheres have been embedded uniformly into the reduced graphene oxide (rGO) to form a new-type Fe3O4/rGO composites through a one-pot solvothermal method. The dielectric properties for these magnetic Fe3O4/rGO composites can be greatly tuned by their different rGO additions. A good impedance matching from the balanced dielectric and magnetic loss is achieved in the Fe3O4/rGO composites with 4 wt% rGO addition, which dominates their excellent microwave absorbing performances including the minimum reflection loss (RL) value of -45 dB at a frequency of 8.96 GHz with a sample thickness of 3.5 mm and an effective absorption bandwidth of 3.2 GHz (below -10 dB) superior to those of the most magnetic materials and carbon-based composites. The controlled Fe3O4/rGO composite structure also exhibits high chemical stability and low density, which shows great potential application in high-performance electromagnetic microwave-absorbing materials.

  16. Electromagnetically induced transparency of a plasmonic metamaterial light absorber based on multilayered metallic nanoparticle sheets.

    PubMed

    Okamoto, Koichi; Tanaka, Daisuke; Degawa, Ryo; Li, Xinheng; Wang, Pangpang; Ryuzaki, Sou; Tamada, Kaoru

    2016-11-08

    In this study, we observed the peak splitting of absorption spectra for two-dimensional sheets of silver nanoparticles due to the electromagnetically induced transparency (EIT) effect. This unique optical phenomenon was observed for the multilayered nanosheets up to 20 layers on a metal substrate, while this phenomenon was not observed on a transparent substrate. The wavelength and intensities of the split peaks depend on the number of layers, and the experimental results were well reproduced by the calculation of the Transfer-Matrix method by employing the effective medium approximation. The Ag nanosheets used in this study can act as a plasmonic metamaterial light absorber, which has a such large oscillator strength. This phenomenon is a fundamental optical property of a thin film on a metal substrate but has never been observed because native materials do not have a large oscillator strength. This new type of EIT effect using a plasmonic metamaterial light absorber presents the potential for the development of future optic and photonic technologies.

  17. Electromagnetically induced transparency of a plasmonic metamaterial light absorber based on multilayered metallic nanoparticle sheets

    NASA Astrophysics Data System (ADS)

    Okamoto, Koichi; Tanaka, Daisuke; Degawa, Ryo; Li, Xinheng; Wang, Pangpang; Ryuzaki, Sou; Tamada, Kaoru

    2016-11-01

    In this study, we observed the peak splitting of absorption spectra for two-dimensional sheets of silver nanoparticles due to the electromagnetically induced transparency (EIT) effect. This unique optical phenomenon was observed for the multilayered nanosheets up to 20 layers on a metal substrate, while this phenomenon was not observed on a transparent substrate. The wavelength and intensities of the split peaks depend on the number of layers, and the experimental results were well reproduced by the calculation of the Transfer-Matrix method by employing the effective medium approximation. The Ag nanosheets used in this study can act as a plasmonic metamaterial light absorber, which has a such large oscillator strength. This phenomenon is a fundamental optical property of a thin film on a metal substrate but has never been observed because native materials do not have a large oscillator strength. This new type of EIT effect using a plasmonic metamaterial light absorber presents the potential for the development of future optic and photonic technologies.

  18. Obliquely Propagating Electromagnetic Waves in Magnetized Kappa Plasmas

    NASA Astrophysics Data System (ADS)

    Gaelzer, R.

    2015-12-01

    The effects of velocity distribution functions (VDFs) that exhibit a power-law dependence on the high-energy tail have been the subjectof intense research by the space plasma community. Such functions, known as kappa or superthermal distributions, have beenfound to provide a better fitting to the VDF measured by spacecraft in the solar wind. One of the problems that is being addressed on this new light is the temperature anisotropy of solar wind protons and electrons. An anisotropic kappa VDF contains a large amount of free energy that can excite waves in the solar wind. Conversely, the wave-particle interaction is important to determine the shape of theobserved particle distributions.In the literature, the general treatment for waves excited by (bi-)Maxwellian plasmas is well-established. However, for kappa distributions, either isotropic or anisotropic, the wave characteristics have been studied mostly for the limiting cases of purely parallel or perpendicular propagation. Contributions for the general case of obliquely-propagating electromagnetic waves have been scarcely reported so far. The absence of a general treatment prevents a complete analysis of the wave-particle interaction in kappa plasmas, since some instabilities, such as the firehose, can operate simultaneously both in the parallel and oblique directions.In a recent work [1], we have obtained expressions for the dielectric tensor and dispersion relations for the low-frequency, quasi-perpendicular dispersive Alfvén waves resulting from a kappa VDF. In the present work, we generalize the formalism introduced by [1] for the general case of electrostatic and/or electromagnetic waves propagating in a kappa plasma in any frequency range and for arbitrary angles.We employ an isotropic distribution, but the methods used here can be easily applied to more general anisotropic distributions,such as the bi-kappa or product-bi-kappa. [1] R. Gaelzer and L. F. Ziebell, Journal of Geophysical Research 119, 9334

  19. Descriptive Study of Electromagnetic Wave Distribution for Various Seating Positions: Using Digital Textbooks

    ERIC Educational Resources Information Center

    Seomun, GyeongAe; Kim, YoungHwan; Lee, Jung-Ah; Jeong, KwangHoon; Park, Seon-A; Kim, Miran; Noh, Wonjung

    2014-01-01

    To better understand environmental electromagnetic wave exposure during the use of digital textbooks by elementary school students, we measured numeric values of the electromagnetic fields produced by tablet personal computers (TPCs). Specifically, we examined the distribution of the electromagnetic waves for various students' seating positions in…

  20. Ring Current-Electromagnetic Ion Cyclotron Waves Coupling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2005-01-01

    The effect of Electromagnetic Ion Cyclotron (EMIC) waves, generated by ion temperature anisotropy in Earth s ring current (RC), is the best known example of wave- particle interaction in the magnetosphere. Also, there is much controversy over the importance of EMIC waves on RC depletion. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt (RB) by EMIC wave scattering during a magnetic storm. That is why the calculation of EMIC waves must be a very critical part of the space weather studies. The new RC model that we have developed and present for the first time has several new features that we have combine together in a one single model: (a) several lower frequency cold plasma wave modes are taken into account; (b) wave tracing of these wave has been incorporated in the energy EMIC wave equation; (c) no assumptions regarding wave shape spectra have been made; (d) no assumptions regarding the shape of particle distribution have been made to calculate the growth rate; (e) pitch-angle, energy, and mix diffusions are taken into account together for the first time; (f) the exact loss-cone RC analytical solution has been found and coupled with bounce-averaged numerical solution of kinetic equation; (g) the EMIC waves saturation due to their modulation instability and LHW generation are included as an additional factor that contributes to this process; and (h) the hot ions were included in the real part of dielectric permittivity tensor. We compare our theoretical results with the different EMIC waves models as well as RC experimental data.

  1. Fe3O4-graphene hybrids: nanoscale characterization and their enhanced electromagnetic wave absorption in gigahertz range

    NASA Astrophysics Data System (ADS)

    Li, Xinghua; Yi, Haibo; Zhang, Junwei; Feng, Juan; Li, Fashen; Xue, Desheng; Zhang, Haoli; Peng, Yong; Mellors, Nigel J.

    2013-03-01

    Fe3O4-graphene hybrid materials have been fabricated by a simple polyol method, and their morphology, chemistry and crystal structure have been characterized at the nanoscale. It is found that each Fe3O4 nanoparticles decorated on the graphene has a polycrystalline fcc spinel structure and a uniform chemical phase. Raman spectroscopy, Fourier transform infrared spectroscopy, thermogravimetry/differential thermal analysis, X-ray diffraction, and transmission electron microscopy suggest that Fe3O4 nanoparticles are chemically bonded to the graphene sheets. Electromagnetic wave absorption shows that the material has a reflection loss exceeding -10 dB in 7.5-18 GHz for an absorber thickness of 1.48-3 mm, accompanying a maximum reflection loss value of -30.1 dB at a 1.48-mm matching thickness and 17.2-GHz matching frequency. Theoretic analysis shows that the electromagnetic wave absorption behavior obeys quarter-wave principles. The results suggest that the magnetic Fe3O4-graphene hybrids are good candidates for the use as a light-weight electromagnetic wave-absorbing material in X- and Ku-bands.

  2. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  3. Planetary electromagnetic waves in the ionospheric E-layer

    NASA Astrophysics Data System (ADS)

    Kaladze, T. D.; Pokhotelov, O. A.; Sagdeev, R. Z.; Stenflo, L.; Shukla, P. K.

    2003-04-01

    The linear theory for the large-scale (λ>103km) electromagnetic (EM) waves in the middle-latitude ionospheric E-layer is developed. The general dispersion relation for these waves is derived. It is shown that the latitudinal inhomogeneity of the geomagnetic field and the angular velocity of the Earth's rotation can lead to the appearance of wave modes in the form of slow and fast EM planetary waves. The slow mode is produced by the dynamo electric field and it represents a generalization of the ordinary Rossby type waves in a rotating atmosphere when the Hall effect in the E-layer is included. The fast mode is a new mode, which is associated with the oscillations of the ionospheric electrons frozen in the geomagnetic field. It represents the variation of the vortical electric field and it arises solely due to the latitudinal gradient of the external magnetic field. The basic characteristics of the wave modes, such as the wavelength, the frequency and the Rayleigh friction, are estimated. Other types of waves, termed slow magnetohydrodynamic (MHD) waves, which are insensitive to the spatial inhomogeneity of the Coriolis and Ampére forces are also reviewed. It is shown that they appear as an admixture of slow Alfvén (SA) and whistler type waves. Such waves can generate variations in the magnetic field from a few tenth to a few hundreds nT. It is stressed that the basic features of the considered waves agree with the general properties of the magnetic perturbations observed at the world network of magnetic and ionospheric stations.

  4. On propagation of electromagnetic and gravitational waves in the expanding Universe

    NASA Astrophysics Data System (ADS)

    Gladyshev, V. O.

    2016-07-01

    The purpose of this study was to obtain an equation for the propagation time of electromagnetic and gravitational waves in the expanding Universe. The velocity of electromagnetic waves propagation depends on the velocity of the interstellar medium in the observer's frame of reference. Gravitational radiation interacts weakly with the substance, so electromagnetic and gravitational waves propagate from a remote astrophysical object to the terrestrial observer at different time. Gravitational waves registration enables the inverse problem solution - by the difference in arrival time of electromagnetic and gravitational-wave signal, we can determine the characteristics of the emitting area of the astrophysical object.

  5. RANS Simulation of the Heave Response of a Two-Body Floating Point Wave Absorber: Preprint

    SciTech Connect

    Yu, Y.; Li, Y.

    2011-03-01

    A preliminary study on a two-body floating wave absorbers is presented in this paper. A Reynolds-Averaged Navier-Stokes computational method is applied for analyzing the hydrodynamic heave response of the absorber in operational wave conditions. The two-body floating wave absorber contains a float section and a submerged reaction section. For validation purposes, our model is first assumed to be locked. The two sections are forced to move together with each other. The locked single body model is used in a heave decay test, where the RANS result is validated with the experimental measurement. For the two-body floating point absorber simulation, the two sections are connected through a mass-spring-damper system, which is applied to simulate the power take-off mechanism under design wave conditions. Overall, the details of the flow around the absorber and its nonlinear interaction with waves are investigated, and the power absorption efficiency of the two-body floating wave absorber in waves with a constant value spring-damper system is examined.

  6. Dispersion properties of compressional electromagnetic waves in quantum dusty magnetoplasmas

    SciTech Connect

    Ali, S.; Shukla, P.K.

    2006-05-15

    A new dispersion relation for low-frequency compressional electromagnetic waves is derived by employing quantum magnetohydrodynamic model and Maxwell equations in cold quantum dusty magnetoplasmas. The latter is composed of inertialess electrons, mobile ions, and immobile charged dust particulates. The dispersion relation for the low-frequency compressional electromagnetic modes is further analyzed for the waves propagating parallel, perpendicular, and oblique to the external magnetic field direction. It is found theoretically and numerically that the quantum parameter {alpha}{sub q}=(n{sub i0}/n{sub e0})({Dirac_h}/2{pi}){sup 2}/(4m{sub e}m{sub i}) affects the real angular frequencies and the phase speeds of the compressional electromagnetic modes. Here, n{sub i0} (n{sub e0}) is the equilibrium number density of the ions (electrons), m{sub e} (m{sub i}) is the electron (ion) mass, and ({Dirac_h}/2{pi}) is the Plank constant divided by 2{pi}.

  7. Resonance of relativistic electrons with electromagnetic ion cyclotron waves

    DOE PAGES

    Denton, R. E.; Jordanova, V. K.; Bortnik, J.

    2015-06-29

    Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron EMIC waves if the total density is large. We show that, for a particular EMIC mode, this dependence is weak due to the dependence of the wave frequency and wave vector on the density. A significant increase in relativistic electron minimum resonant energy might occur for the H band EMIC mode only for small density, but no changes in parameters significantly decrease the minimum resonant energy from a nominal value. The minimum resonant energy depends most strongly on the thermal velocity associated with the field line motionmore » of the hot ring current protons that drive the instability. High density due to a plasmasphere or plasmaspheric plume could possibly lead to lower minimum resonance energy by causing the He band EMIC mode to be dominant. We demonstrate these points using parameters from a ring current simulation.« less

  8. Nonresonant interaction of heavy ions with electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Berchem, J.; Gendrin, R.

    1985-01-01

    The motion of a heavy ion in the presence of an intense ultralow-frequency electromagnetic wave propagating along the dc magnetic field is analyzed. Starting from the basic equations of motion and from their associated two invariants, the heavy ion velocity-space trajectories are drawn. It is shown that after a certain time, particles whose initial phase angles are randomly distributed tend to bunch together, provided that the wave intensity b-sub-1 is sufficiently large. The importance of these results for the interpretation of the recently observed acceleration of singly charged He ions in conjunction with the occurrence of large-amplitude ion cyclotron waves in the equatorial magnetosphere is discussed.

  9. Nonlinear Electromagnetic Waves in a Degenerate Electron-Positron Plasma

    NASA Astrophysics Data System (ADS)

    El-Labany, S. K.; El-Taibany, W. F.; El-Samahy, A. E.; Hafez, A. M.; Atteya, A.

    2015-08-01

    Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed.

  10. Resonance of relativistic electrons with electromagnetic ion cyclotron waves

    SciTech Connect

    Denton, R. E.; Jordanova, V. K.; Bortnik, J.

    2015-06-29

    Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron EMIC waves if the total density is large. We show that, for a particular EMIC mode, this dependence is weak due to the dependence of the wave frequency and wave vector on the density. A significant increase in relativistic electron minimum resonant energy might occur for the H band EMIC mode only for small density, but no changes in parameters significantly decrease the minimum resonant energy from a nominal value. The minimum resonant energy depends most strongly on the thermal velocity associated with the field line motion of the hot ring current protons that drive the instability. High density due to a plasmasphere or plasmaspheric plume could possibly lead to lower minimum resonance energy by causing the He band EMIC mode to be dominant. We demonstrate these points using parameters from a ring current simulation.

  11. THE GENERATION OF THERMOELASTIC STRESS WAVES BY IMPULSIVE ELECTROMAGNETIC RADIATION.

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , ABSORPTION), (*STRESSES, ELECTROMAGNETIC RADIATION ), SURFACE PROPERTIES, INTERACTIONS, HEAT TRANSFER, ELASTIC PROPERTIES, ELECTROMAGNETIC PULSES, LASERS, MATHEMATICAL ANALYSIS, BOUNDARY VALUE PROBLEMS, SOLIDS

  12. The role of magnetic dipoles and non-zero-order Bragg waves in metamaterial perfect absorbers.

    PubMed

    Zeng, Yong; Chen, Hou-Tong; Dalvit, Diego A R

    2013-02-11

    We develop a simple treatment of a metamaterial perfect absorber (MPA) based on grating theory. We analytically prove that the condition of MPA requires the existence of two currents, which are nearly out of phase and have almost identical amplitude, akin to a magnetic dipole. Furthermore, we show that non-zero-order Bragg modes within the MPA may consume electromagnetic energy significantly.

  13. Massively Sub-wavelength Guiding of Electromagnetic Waves

    PubMed Central

    Hooper, I. R.; Tremain, B.; Dockrey, J. A.; Hibbins, A. P.

    2014-01-01

    Recently a new form of ultra-thin flexible waveguide consisting of a conducting comb-like structure with a thickness of the order of 1/600th of the operating wavelength was presented. However, whilst the thickness of the guide was massively sub-wavelength, the remaining dimensions (the height and period of the comb) were much longer. In this paper we propose, and experimentally verify, that a modified guiding geometry consisting of a chain of ultra-thin conducting spirals allows guiding of electromagnetic waves with wavelengths that are many times (40+) longer than any characteristic dimension of the guide, enabling super-sub-wavelength guiding and localisation of electromagnetic energy. PMID:25510662

  14. Explaining Electromagnetic Plane Waves in a Vacuum at the Introductory Level

    ERIC Educational Resources Information Center

    Allred, Clark L.; Della-Rose, Devin J.; Flusche, Brian M.; Kiziah, Rex R.; Lee, David J.

    2010-01-01

    A typical introduction to electromagnetic waves in vacuum is illustrated by the following quote from an introductory physics text: "Maxwell's equations predict that an electromagnetic wave consists of oscillating electric and magnetic fields. The changing fields induce each other, which maintains the propagation of the wave; a changing electric…

  15. Electromagnetic wave absorption of polymeric nanocomposites based on ferrite with a spinel and hexagonal crystal structure

    NASA Astrophysics Data System (ADS)

    Drmota, A.; Koselj, J.; Drofenik, M.; Žnidaršič, A.

    2012-03-01

    We have investigated composites designed for microwave absorption based on magnetic filler, composed of phases within the SrO-Fe2O3 system, embedded in a polyphenylene sulfide matrix with a concentration ratio of 80:20 by weight. The formation of the nanosized particles of SrFe12O19 and Fe3O4, as the principal magnetic phases was achieved via the co-precipitation of Sr2+/Fe3+ ions using different molar ratios. The various precursors obtained were calcined between 600 °C and 900 °C in air. The electromagnetic parameters of the composites were measured with a vector network analyzer at 400 MHz to 32 GHz. The results show that with a composite composed of a complex magnetic filler comprising the nanoparticles of two magnetically diverse phases, i.e., a spinel phase as the electromagnetic wave absorber in the lower GHz range and a hexagonal phase operating at a higher GHz range, above 32 GHz, a microwave absorber with an broad absorption range can be prepared.

  16. Low Reflection Absorbers for Electromagnetic Waves (Reflexionsarme Absorber Fuer Elektromagnetische Wellen)

    DTIC Science & Technology

    1960-11-01

    should be briefly recalled. They consist of air sound, as a rule, of porous substances, mineral wool , glass wool, and similar substances, whose...nonreflecting room, then small particles of graphite will -17- pi m u . I be inserted into the pores of the porous glass wool or mineral wool . Such wedges

  17. Electromagnetic wave method for mapping subterranean earth formations

    DOEpatents

    Shuck, Lowell Z.; Fasching, George E.; Balanis, Constantine A.

    1977-01-01

    The present invention is directed to a method for remotely mapping subterranean coal beds prior to and during in situ gasification operations. This method is achieved by emplacing highly directional electromagnetic wave transmitters and receivers in bore holes penetrating the coal beds and then mapping the anomalies surrounding each bore hole by selectively rotating and vertically displacing the directional transmitter in a transmitting mode within the bore hole, and thereafter, initiating the gasification of the coal at bore holes separate from those containing the transmitters and receivers and then utilizing the latter for monitoring the burn front as it progresses toward the transmitters and receivers.

  18. Broadband unidirectional behavior of electromagnetic waves based on transformation optics

    NASA Astrophysics Data System (ADS)

    Zang, Xiaofei; Zhu, Yiming; Ji, Xuebin; Chen, Lin; Hu, Qing; Zhuang, Songlin

    2017-01-01

    High directive antennas are fundamental elements for microwave communication and information processing. Here, inspired by the method of transformation optics, we propose and demonstrate a transformation medium to control the transmission path of a point source, resulting in the unidirectional behavior of electromagnetic waves (directional emitter) without any reflectors. The network of inductor-capacitor transmission lines is designed to experimentally realize the transformation medium. Furthermore, the designed device can work in a broadband frequency range. The unidirectional-manner-based device demonstrated in this work will be an important step forward in developing a new type of directive antennas.

  19. Dispersion relations for electromagnetic wave propagation in chiral plasmas

    SciTech Connect

    Gao, M. X.; Guo, B. Peng, L.; Cai, X.

    2014-11-15

    The dispersion relations for electromagnetic wave propagation in chiral plasmas are derived using a simplified method and investigated in detail. With the help of the dispersion relations for each eignwave, we explore how the chiral plasmas exhibit negative refraction and investigate the frequency region for negative refraction. The results show that chirality can induce negative refraction in plasmas. Moreover, both the degree of chirality and the external magnetic field have a significant effect on the critical frequency and the bandwidth of the frequency for negative refraction in chiral plasmas. The parameter dependence of the effects is calculated and discussed.

  20. Broadband unidirectional behavior of electromagnetic waves based on transformation optics

    PubMed Central

    Zang, XiaoFei; Zhu, YiMing; Ji, XueBin; Chen, Lin; Hu, Qing; Zhuang, SongLin

    2017-01-01

    High directive antennas are fundamental elements for microwave communication and information processing. Here, inspired by the method of transformation optics, we propose and demonstrate a transformation medium to control the transmission path of a point source, resulting in the unidirectional behavior of electromagnetic waves (directional emitter) without any reflectors. The network of inductor-capacitor transmission lines is designed to experimentally realize the transformation medium. Furthermore, the designed device can work in a broadband frequency range. The unidirectional-manner-based device demonstrated in this work will be an important step forward in developing a new type of directive antennas. PMID:28106115

  1. Robust imaging with electromagnetic waves in noisy environments

    NASA Astrophysics Data System (ADS)

    Borcea, Liliana; Garnier, Josselin

    2016-10-01

    We study imaging with an array of sensors that probes a medium with single frequency electromagnetic waves and records the scattered electric field. The medium is known and homogenous except for some small and penetrable inclusions. The goal of inversion is to locate and characterize these inclusions from the data collected by the array, which are corrupted by additive noise. We use results from random matrix theory to obtain a robust inversion method. We assess its performance with numerical simulations and quantify the benefit of measuring more than one component of the scattered electric field.

  2. Nearly non-scattering electromagnetic wave set and its application

    NASA Astrophysics Data System (ADS)

    Liu, Hongyu; Wang, Yuliang; Zhong, Shuhui

    2017-04-01

    For any inhomogeneous compactly supported electromagnetic (EM) medium, it is shown that there exists an infinite set of linearly independent EM waves which generate nearly vanishing scattered wave fields. If the inhomogeneous medium is coated with a layer of properly chosen conducting medium, then the wave set is generated from the Maxwell-Herglotz approximation to the interior perfectly electric conducting or perfectly magnetic conducting eigenfunctions and depends only on the shape of the inhomogeneous medium. If no such a conducting coating is used, then the wave set is generated from the Maxwell-Herglotz approximation to the generalised interior transmission eigenfunctions and depends on both the content and shape of the inhomogeneous medium. We characterise the nearly non-scattering wave sets in both cases with sharp estimates. The results can be used to give a conceptual design of a novel shadowless lamp. The crucial ingredient is to properly choose the source of the lamp so that nearly no shadow will be produced by surgeons operating under the lamp.

  3. Scattering of Electromagnetic Waves by Drift Vortex in Plasma

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Chen, Yinhua; Wang, Ge

    2008-02-01

    In a quasi-two-dimensional model, the scattering of incident ordinary electromagnetic waves by a dipole-electrostatic drift vortex is studied with first-order Born approximation. The distribution of the scattering cross-section and total cross-section are evaluated analytically in different approximate conditions, and the physical interpretations are discussed. When the wavelength of incident wave is much longer than the vortex radius (kia ll 1), it is found that the angle at which the scattering cross-section reaches its maxim depends significantly on the approximation of the parameters of the vortex used. It is also found that the total scattering cross-section has an affinitive relation with the parameters of the plasma, while it is irrelevant to the frequency of the incident wave in a wide range of parameters of the vortex. In a totally different range of parameters when incident wave is in the radar-frequency range (then kia ll 1, the wavelength of incident wave is much shorter than the vortex radius), the numerical procedure is conducted with computer in order to obtain the distribution and the total expression of the scattering cross-section. Then it is found that the total scattering cross-section in the low frequency range is much larger than that in high frequency range, so the scattering is more effective in the low frequency range than in high frequency range.

  4. Selective generation of ultrasonic Lamb waves by electromagnetic acoustic transducers

    NASA Astrophysics Data System (ADS)

    Li, Ming-Liang; Deng, Ming-Xi; Gao, Guang-Jian

    2016-12-01

    In this paper, we describe a modal expansion approach for the analysis of the selective generation of ultrasonic Lamb waves by electromagnetic acoustic transducers (EMATs). With the modal expansion approach for waveguide excitation, an analytical expression of the Lamb wave’s mode expansion coefficient is deduced, which is related to the driving frequency and the geometrical parameters of the EMAT’s meander coil, and lays a theoretical foundation for exactly analyzing the selective generation of Lamb waves with EMATs. The influences of the driving frequency on the mode expansion coefficient of ultrasonic Lamb waves are analyzed when the EMAT’s geometrical parameters are given. The numerical simulations and experimental examinations show that the ultrasonic Lamb wave modes can be effectively regulated (strengthened or restrained) by choosing an appropriate driving frequency of EMAT, with the geometrical parameters given. This result provides a theoretical and experimental basis for selectively generating a single and pure Lamb wave mode with EMATs. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474361 and 11274388).

  5. Guided electromagnetic waves observed on a conducting ionospheric tether

    NASA Astrophysics Data System (ADS)

    James, H. G.; Balmain, K. G.

    2001-01-01

    On the up leg of its flight through the auroral nightside ionosphere to an apogee of 824 km, the tethered double payload Observations of Electric Field Distributions in the Ionospheric Plasma: A Unique Strategy (OEDIPUS) C was the site of experiments on wire-guided electromagnetic (EM) waves. Waves were transmitted from the upper subpayload to a receiver on the lower subpayload along a conducting wire aligned within a few degrees of the Earth's magnetic field. Such EM waves were observed at almost all frequencies in the range 0.1-8.0 MHz. There was a deep stop band between the cyclotron and upper hybrid resonance frequencies where the cold plasma theory predicts a propagation cutoff, and there were shallower attenuation bands at frequencies where hot-plasma electrostatic waves may affect the guided EM modes. Resonances of the wire-guided waves with the tether length were observed throughout the entire tethered portion of the flight. The resonances appear as a set of fringes when all the data are presented in a frequency-versus-time summary. The fringe shapes in this summary have been compared with the predictions of an early theory, which give generally good agreement. The exceptions are frequencies close to the stop band, where cold-plasma dispersion effects are expected to be greatest. Another theory based on a different derivation of the dispersion relation includes a vacuum sheath gap outside the conductor. The absolute fringe intensities and positions predicted agree moderately well with the observations.

  6. Parametric decay of an extraordinary electromagnetic wave in relativistic plasma

    SciTech Connect

    Dorofeenko, V. G.; Krasovitskiy, V. B.; Turikov, V. A.

    2015-03-15

    Parametric instability of an extraordinary electromagnetic wave in plasma preheated to a relativistic temperature is considered. A set of self-similar nonlinear differential equations taking into account the electron “thermal” mass is derived and investigated. Small perturbations of the parameters of the heated plasma are analyzed in the linear approximation by using the dispersion relation determining the phase velocities of the fast and slow extraordinary waves. In contrast to cold plasma, the evanescence zone in the frequency range above the electron upper hybrid frequency vanishes and the asymptotes of both branches converge. Theoretical analysis of the set of nonlinear equations shows that the growth rate of decay instability increases with increasing initial temperature of plasma electrons. This result is qualitatively confirmed by numerical simulations of plasma heating by a laser pulse injected from vacuum.

  7. Nonresonant interactions of electromagnetic ion cyclotron waves with relativistic electrons

    NASA Astrophysics Data System (ADS)

    Chen, Lunjin; Thorne, Richard M.; Bortnik, Jacob; Zhang, Xiao-Jia

    2016-10-01

    The dynamics of relativistic electrons traveling through a parallel-propagating, monochromatic electromagnetic ion cyclotron (EMIC) wave in the Earth's dipole field are investigated via test particle simulations. Both resonant and nonresonant responses in electron pitch angle are considered, and the differences between the two are highlighted. Nonresonant electrons, with energies below the minimum resonant energy down to hundreds of keV, are scattered stochastically in pitch angle and can be scattered into the atmospheric loss cone. The nonresonant effect is attributed to the spatial edge associated with EMIC wave packets. A condition for effective nonresonant response is also provided. This effect is excluded from current quasi-linear theory and can be a potentially important loss mechanism of relativistic and subrelativistic electrons in the radiation belts.

  8. Electromagnetic Wave Shieding Effectiveness of Carbon Fiber Sheet Coated Ferrite Film by Microwave-Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Murakami, Ri Ichi; Yamamoto, Hidetoshi; Kim, Chan Kong; Yim, Cheol Mun; Kim, Yun Hae

    The developments of electromagnetic wave shielding materials are strongly required because the malfunction of electronic equipment, mobile phone and wireless LAN avoids. In this study, it was investigated that the electromagnetic shielding effectiveness of carbon fiber sheets were enhanced by the ferrite which was coated by the microwave hydrothermal process. For coated carbon fiber sheet, the effects of ferrite and lamination of carbon fiber textile on the electromagnetic wave shielding effectiveness were discussed. In the range of frequency (100 1 GHz), the electromagnetic wave shielding effectiveness was measured by using TEM-Cell. The electromagnetic wave shielding effectiveness was greater for the coated carbon fiber sheets than for the uncoated carbon fiber sheets. When the insulation film was located between two carbon fiber sheets, the electromagnetic wave shielding effectiveness increased.

  9. Frequency Domain Modelling of Electromagnetic Wave Propagation in Layered Media

    NASA Astrophysics Data System (ADS)

    Schmidt, Felix; Wagner, Norman; Lünenschloß, Peter; Toepfer, Hannes; Dietrich, Peter; Kaliorias, Andreas; Bumberger, Jan

    2015-04-01

    The amount of water in porous media such as soils and rocks is a key parameter when water resources are under investigation. Especially the quantitative spatial distribution and temporal evolution of water contents in soil formations are needed. In high frequency electromagnetic applications soil water content is quantitatively derived from the propagation behavior of electromagnetic waves along waveguides embedded in soil formations. The spatial distribution of the dielectric material properties along the waveguide can be estimated by numerical solving of the inverse problem based on the full wave forward model in time or frequency domain. However, current approaches mostly neglect or approximate the frequency dependence of the electromagnetic material properties of transfer function of the waveguide. As a first prove of concept a full two port broadband frequency domain forward model for propagation of transverse electromagnetic (TEM) waves in coaxial waveguide has been implemented. It is based on the propagation matrix approach for layered transmission line sections Depending on the complexity of the material different models for the frequency dependent complex permittivity were applied. For the validation of the model a broadband frequency domain measurement with network analyzer technique was used. The measurement is based on a 20 cm long 50 Ohm 20/46 coaxial transmission line cell considering inhomogeneous material distributions. This approach allows (i) an increase of the waveguide calibration accuracy in comparison to conventional TDR based technique and (ii) the consideration of the broadband permittivity spectrum of the porous material. In order to systematic analyze the model, theoretical results were compared with measurements as well as 3D broadband finite element modeling of homogeneous and layered media in the coaxial transmission line cell. Defined standards (Teflon, dry glass beads, de-ionized water) were placed inside the line as the dielectric

  10. Frequency Domain Modelling of Electromagnetic Wave Propagation in Layered Media

    NASA Astrophysics Data System (ADS)

    Schmidt, Felix; Lünenschloss, Peter; Mai, Juliane; Wagner, Norman; Töpfer, Hannes; Bumberger, Jan

    2016-04-01

    The amount of water in porous media such as soils and rocks is a key parameter when water resources are under investigation. Especially the quantitative spatial distribution and temporal evolution of water contents in soil formations are needed. In high frequency electromagnetic applications soil water content is quantitatively derived from the propagation behavior of electromagnetic waves along waveguides embedded in soil formations. The spatial distribution of the dielectric material properties along the waveguide can be estimated by numerical solving of the inverse problem based on the full wave forward model in time or frequency domain. However, current approaches mostly neglect or approximate the frequency dependence of the electromagnetic material properties of transfer function of the waveguide. As a first prove of concept a full two port broadband frequency domain forward model for propagation of transverse electromagnetic (TEM) waves in coaxial waveguide has been implemented. It is based on the propagation matrix approach for layered transmission line sections. Depending on the complexity of the material different models for the frequency dependent complex permittivity were applied. For the validation of the model a broadband frequency domain measurement with network analyzer technique was used. The measurement is based on a 20 cm long 50 Ohm 20/46 coaxial transmission line cell considering inhomogeneous material distributions. This approach allows (i) an increase of the waveguide calibration accuracy in comparison to conventional TDR based technique and (ii) the consideration of the broadband permittivity spectrum of the porous material. In order to systematic analyze the model, theoretical results were compared with measurements as well as 3D broadband finite element modeling of homogeneous and layered media in the coaxial transmission line cell. Defined standards (Teflon, dry glass beads, de-ionized water) were placed inside the line as the dielectric

  11. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-03-01

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4.7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

  12. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature.

    PubMed

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-03-19

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4 · 7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

  13. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature

    PubMed Central

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-01-01

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4·7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures. PMID:25788158

  14. Scattering of strong electromagnetic wave by relativistic electrons: Thomson and Compton regimes

    NASA Astrophysics Data System (ADS)

    Potylitsyn, A. P.; Kolchuzhkin, A. M.

    2017-04-01

    The processes of the nonlinear Compton and the nonlinear Thomson scattering in a field of intense plane electromagnetic wave in terms of photon yield have been considered. The quantum consideration of the Compton scattering process allows us to calculate the probability of a few successive collisions k of an electron with laser photons accompanied by the absorption of n photons (nonlinear regime) when the number of collisions and the number of absorbed photons are of random quantities. The photon spectrum of the nonlinear Thomson scattering process was obtained from the classical formula for intensity using the Planck's law. The conditions for which the difference between the classical and the quantum regimes is manifested was obtained. Such a condition is determined by a discrete quantum radiation mechanism, namely, by the mean number of photons k bar emitted by an electron passing through the laser pulse.

  15. Zero-group-velocity propagation of electromagnetic wave through nanomaterial

    NASA Astrophysics Data System (ADS)

    Fan, Taian

    This research will investigate the problem on the propagation of electromagnetic wave through a specific nanomaterial. The nanomaterial analyzed is a material consisting of a field of Pt nanorods. This field of Pt nanorods are deposited on a substrate which consists of a RuO2 nano structure. When the nanorod is exposed to an electron beam emitted by a TEM (Transmission electron microscopy). A wave disturbance has been observed. A video taken within the chamber shows a wave with a speed in the scale of um/s (10-6 m/s), which is 14 orders of magnitude lower than speed of light in free space (approximate 3x108 m/s ). A physical and mathematical model is developed to explain this phenomenon. Due to the process of fabrication, the geometry of the decorated Pt nanorod field is assumed to be approximately periodic. The nanomaterials possess properties similar to a photonic crystal. Pt, as a noble metal, shows dispersive behaviours that is different from those ones of a perfect or good conductors. A FDTD algorithm is implemented to calculate the band diagram of the nanomaterials. To explore the dispersive properties of the Pt nanorod field, the FDTD algorithm is corrected with a Drude Model. The analysis of the corrected band diagram illustrates that the group velocity of the wave packet propagating through the nanomaterial can be positive, negative or zero. The possible zero-group velocity is therefore used to explain the extremely low velocity of wave (wave envelope) detected in the TEM.

  16. Full-wave Electromagnetic Field Simulations of Lower Hybrid Waves in Tokamaks

    SciTech Connect

    Wright, J.C.; Bonoli, P. T.; Brambilla, M.; D'Azevedo, E.; Berry, L.A.; Batchelor, D.B.; Jaeger, E.F.; Carter, M.D.; Phillips, C.K.; Okuda, H.; Harvey, R.W.; Myra, J.R.; D'Ippolito, D.A.; Smithe, D.N.

    2005-09-26

    The most common method for treating wave propagation in tokamaks in the lower hybrid range of frequencies (LHRF) has been toroidal ray tracing, owing to the short wavelengths (relative to the system size) found in this regime. Although this technique provides an accurate description of 2D and 3D plasma inhomogeneity effects on wave propagation, the approach neglects important effects related to focusing, diffraction, and finite extent of the RF launcher. Also, the method breaks down at plasma cutoffs and caustics. Recent adaptation of full-wave electromagnetic field solvers to massively parallel computers has made it possible to accurately resolve wave phenomena in the LHRF. One such solver, the TORIC code, has been modified to simulate LH waves by implementing boundary conditions appropriate for coupling the fast electromagnetic and the slow electrostatic waves in the LHRF. In this frequency regime the plasma conductivity operator can be formulated in the limits of unmagnetized ions and strongly magnetized electrons, resulting in a relatively simple and explicit form. Simulations have been done for parameters typical of the planned LHRF experiments on Alcator C-Mod, demonstrating fully resolved fast and slow LH wave fields using a Maxwellian non-relativistic plasma dielectric. Significant spectral broadening of the injected wave spectrum and focusing of the wave fields have been found, especially at caustic surfaces. Comparisons with toroidal ray tracing have also been done and differences between the approaches have been found, especially for cases where wave caustics form. The possible role of this diffraction-induced spectral broadening in filling the spectral gap in LH heating and current drive will be discussed.

  17. Global Navigation Satellite System Multipath Mitigation Using a Wave-Absorbing Shield.

    PubMed

    Yang, Haiyan; Yang, Xuhai; Sun, Baoqi; Su, Hang

    2016-08-22

    Code multipath is an unmanaged error source in precise global navigation satellite system (GNSS) observation processing that limits GNSS positioning accuracy. A new technique for mitigating multipath by installing a wave-absorbing shield is presented in this paper. The wave-absorbing shield was designed according to a GNSS requirement of received signals and collected measurements to achieve good performance. The wave-absorbing shield was installed at the KUN1 and SHA1 sites of the international GNSS Monitoring and Assessment System (iGMAS). Code and carrier phase measurements of three constellations were collected on the dates of the respective installations plus and minus one week. Experiments were performed in which the multipath of the measurements obtained at different elevations was mitigated to different extents after applying the wave-absorbing shield. The results of an analysis and comparison show that the multipath was mitigated by approximately 17%-36% on all available frequencies of BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), and Global Navigation Satellite System (GLONASS) satellites. The three-dimensional accuracies of BDS, GPS, and GLONASS single-point positioning (SPP) were, respectively, improved by 1.07, 0.63 and 0.49 m for the KUN1 site, and by 0.72, 0.79 and 0.73 m for the SHA1 site. Results indicate that the multipath of the original observations was mitigated by using the wave-absorbing shield.

  18. Global Navigation Satellite System Multipath Mitigation Using a Wave-Absorbing Shield

    PubMed Central

    Yang, Haiyan; Yang, Xuhai; Sun, Baoqi; Su, Hang

    2016-01-01

    Code multipath is an unmanaged error source in precise global navigation satellite system (GNSS) observation processing that limits GNSS positioning accuracy. A new technique for mitigating multipath by installing a wave-absorbing shield is presented in this paper. The wave-absorbing shield was designed according to a GNSS requirement of received signals and collected measurements to achieve good performance. The wave-absorbing shield was installed at the KUN1 and SHA1 sites of the international GNSS Monitoring and Assessment System (iGMAS). Code and carrier phase measurements of three constellations were collected on the dates of the respective installations plus and minus one week. Experiments were performed in which the multipath of the measurements obtained at different elevations was mitigated to different extents after applying the wave-absorbing shield. The results of an analysis and comparison show that the multipath was mitigated by approximately 17%–36% on all available frequencies of BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), and Global Navigation Satellite System (GLONASS) satellites. The three-dimensional accuracies of BDS, GPS, and GLONASS single-point positioning (SPP) were, respectively, improved by 1.07, 0.63 and 0.49 m for the KUN1 site, and by 0.72, 0.79 and 0.73 m for the SHA1 site. Results indicate that the multipath of the original observations was mitigated by using the wave-absorbing shield. PMID:27556466

  19. Frequency dependent power and energy flux density equations of the electromagnetic wave

    NASA Astrophysics Data System (ADS)

    Muhibbullah, M.; Haleem, Ashraf M. Abdel; Ikuma, Yasuro

    The calculation of the power and energy of the electromagnetic wave is important for numerous applications. There are some equations to compute the power and energy density of the electromagnetic wave radiation. For instance, the Poynting vector is frequently used to calculate the power density. However those including the Poynting vector are not perfect to represent the actual values because the equations are frequency independent. In the present study we have derived the frequency-dependent equations to calculate the power and energy flux density of the electromagnetic wave by help of the classical electromagnetic theories. It is seems that the Poynting vector with a certain electric and magnetic fields is correct only for a specific frequency. However our equations are perfect to calculate the values of the power and energy flux density for all frequencies of the electromagnetic radiation. The equations may help to develop the applications of the electromagnetic wave radiation.

  20. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

    2014-04-01

    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  1. Examination of Bursty Electromagnetic Waves Observed During Intervals of Turbulent Magnetosheath Reconnection

    NASA Technical Reports Server (NTRS)

    Adrian, Mark L.; Wendel, D. E.

    2011-01-01

    We investigate observations of intense bursts of electromagnetic waves in association with magnetic reconnection in the turbulent magnetosheath. These structured, broadband bursts occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed at local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic waves and quantify their proximity to X- and O-nulls.

  2. Ionospheric electron acceleration by electromagnetic waves near regions of plasma resonances

    NASA Astrophysics Data System (ADS)

    Villalon, Elena

    1989-03-01

    Electron acceleration by electromagnetic fields propagating in the inhomogeneous ionospheric plasma is investigated. It is found that high-amplitude short wavelength electrostatic waves are generated by the incident electromagnetic fields that penetrate the radio window. These waves can very efficiently transfer their energy to the electrons if the incident frequency is near the second harmonic of the cyclotron frequency.

  3. Experimental demonstration of a transparent graphene millimetre wave absorber with 28% fractional bandwidth at 140 GHz

    NASA Astrophysics Data System (ADS)

    Wu, Bian; Tuncer, Hatice M.; Naeem, Majid; Yang, Bin; Cole, Matthew T.; Milne, William I.; Hao, Yang

    2014-02-01

    The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz. Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.

  4. Localized Electromagnetic Waves: Interactions with Surfaces and Nanostructures

    NASA Astrophysics Data System (ADS)

    Anderson, Nicholas R.

    The interaction of electromagnetic waves with nanostructures is an important area of research for signal processing devices, magnetic data storage, biosensors and a variety of other applications. In this work, we present analytic and numerical calculations for oscillating electric and magnetic fields coupling with excitations in magnetic materials as well as metallic and dielectric materials, near their resonance frequencies. One of the problems with the miniaturization of signal processing components is that there is a cutoff frequency associated with the transverse electric (TE) mode in waveguides. However, it is usually the TE mode which is used to achieve nonreciprocity for devices such as isolators. As a first step to circumvent this problem we looked at the absorption of electromagnetic waves in an antiferromagnet and a ferrite when the incident wave is at an arbitrary angle with respect to the magnetization direction. We calculated reflectivity and attenuated total reflectivity and found absorption and nonreciprocity, asymmetric behavior for waves traveling in opposite directions, for a broad range of propagation angles. Subsequently we also performed calculations for a transverse magnetic mode in a waveguide. The wave was allowed to propagate at an arbitrary angle with respect to the magnetization direction of the ferrite in the waveguide. We again found nonreciprocity for a wide range of angles. Our results show that this system could be used as an on-chip isolator with isolation values over 75 dB/cm in the 50 GHz range. We explored another signal processing device operating in the GHz range: a nonlinear phase shifter. Using Fe as the magnetic material allows the phase shifter to operate over a wide frequency and power range. We found a differential phase shift of greater than 50° over 3 cm for this device. The theoretical results compared well with experimental measurements. Finally, we study surface plasmon polaritons propagating along a metallic

  5. Conical refraction of elastic waves in absorbing crystals

    SciTech Connect

    Alshits, V. I. Lyubimov, V. N.

    2011-10-15

    The absorption-induced acoustic-axis splitting in a viscoelastic crystal with an arbitrary anisotropy is considered. It is shown that after 'switching on' absorption, the linear vector polarization field in the vicinity of the initial degeneracy point having an orientation singularity with the Poincare index n = {+-}1/2, transforms to a planar distribution of ellipses with two singularities n = {+-}1/4 corresponding to new axes. The local geometry of the slowness surface of elastic waves is studied in the vicinity of new degeneracy points and a self-intersection line connecting them. The absorption-induced transformation of the classical picture of conical refraction is studied. The ellipticity of waves at the edge of the self-intersection wedge in a narrow interval of propagation directions drastically changes from circular at the wedge ends to linear in the middle of the wedge. For the wave normal directed to an arbitrary point of this wedge, during movement of the displacement vector over the corresponding polarization ellipse, the wave ray velocity s runs over the same cone describing refraction in a crystal without absorption. In this case, the end of the vector moves along a universal ellipse whose plane is orthogonal to the acoustic axis for zero absorption. The areal velocity of this movement differs from the angular velocity of the displacement vector on the polarization ellipse only by a constant factor, being delayed by {pi}/2 in phase. When the wave normal is localized at the edge of the wedge in its central region, the movement of vector s along the universal ellipse becomes drastically nonuniform and the refraction transforms from conical to wedge-like.

  6. Electromagnetic waves near the proton cyclotron frequency: Stereo observations

    SciTech Connect

    Jian, L. K.; Wei, H. Y.; Russell, C. T.; Luhmann, J. G.; Klecker, B.; Omidi, N.; Isenberg, P. A.; Goldstein, M. L.; Figueroa-Viñas, A.; Blanco-Cano, X.

    2014-05-10

    Transverse, near-circularly polarized, parallel-propagating electromagnetic waves around the proton cyclotron frequency were found sporadically in the solar wind throughout the inner heliosphere. They could play an important role in heating and accelerating the solar wind. These low-frequency waves (LFWs) are intermittent but often occur in prolonged bursts lasting over 10 minutes, named 'LFW storms'. Through a comprehensive survey of them from Solar Terrestrial Relations Observatory A using dynamic spectral wave analysis, we have identified 241 LFW storms in 2008, present 0.9% of the time. They are left-hand (LH) or right-hand (RH) polarized in the spacecraft frame with similar characteristics, probably due to Doppler shift of the same type of waves or waves of intrinsically different polarities. In rare cases, the opposite polarities are observed closely in time or even simultaneously. Having ruled out interplanetary coronal mass ejections, shocks, energetic particles, comets, planets, and interstellar ions as LFW sources, we discuss the remaining generation scenarios: LH ion cyclotron instability driven by greater perpendicular temperature than parallel temperature or by ring-beam distribution, and RH ion fire hose instability driven by inverse temperature anisotropy or by cool ion beams. The investigation of solar wind conditions is compromised by the bias of the one-dimensional Maxwellian fit used for plasma data calibration. However, the LFW storms are preferentially detected in rarefaction regions following fast winds and when the magnetic field is radial. This preference may be related to the ion cyclotron anisotropy instability in fast wind and the minimum in damping along the radial field.

  7. Precipitation of Relativistic Electrons by Electromagnetic Ion Cyclotron (EMIC) Waves

    NASA Astrophysics Data System (ADS)

    Denton, R. E.

    2015-12-01

    We use the electromagnetic ion cyclotron (EMIC) wave fields produced in a two dimensional hybrid code simulation (full dynamics particle ions, but inertialess fluid electrons) in dipole geometry in order to investigate the effect of magnetospheric EMIC waves on relativistic electrons. The plane of the simulation includes variation in the L shell direction and along magnetic field lines. Relativistic test particle electrons are inserted into the simulation when the wave fields are near their maximum amplitude. These electrons can be scattered into the loss cone so that they precipitate into the ionosphere. We find the effective pitch angle diffusion coefficient and probability of precipitation using these test particles. The pitch angle diffusion coefficients are largest for relativistic energies greater than 2 MeV, though they may be substantial for lower energies. The probability of precipitation is highest for low energy particles at small initial equatorial pitch angle. For high initial equatorial pitch angles, the probability of precipitation increases greatly with respect to particle energy. Starting from an isotropic pitch angle distribution of relativistic electrons with a Gaussian spread in the relativistic momentum, we find only a small drop in the probability of precipitation during 13 s time as the particle energy decreases. But that result depends on the initial pitch angle distribution. Starting with a distribution of particles steeply peaked at 90° initial equatorial pitch angle, the probability of precipitation would be greater for high-energy particles. We will discuss the mechanism of pitch angle scattering.

  8. Dynamical control on helicity of electromagnetic waves by tunable metasurfaces.

    PubMed

    Xu, He-Xiu; Sun, Shulin; Tang, Shiwei; Ma, Shaojie; He, Qiong; Wang, Guang-Ming; Cai, Tong; Li, Hai-Peng; Zhou, Lei

    2016-06-08

    Manipulating the polarization states of electromagnetic (EM) waves, a fundamental issue in optics, attracted intensive attention recently. However, most of the devices realized so far are either too bulky in size, and/or are passive with only specific functionalities. Here we combine theory and experiment to demonstrate that, a tunable metasurface incorporating diodes as active elements can dynamically control the reflection phase of EM waves, and thus exhibits unprecedented capabilities to manipulate the helicity of incident circular-polarized (CP) EM wave. By controlling the bias voltages imparted on the embedded diodes, we demonstrate that the device can work in two distinct states. Whereas in the "On" state, the metasurface functions as a helicity convertor and a helicity hybridizer within two separate frequency bands, it behaves as a helicity keeper within an ultra-wide frequency band in the "Off" state. Our findings pave the way to realize functionality-switchable devices related to phase control, such as frequency-tunable subwavelength cavities, anomalous reflectors and even holograms.

  9. Dynamical control on helicity of electromagnetic waves by tunable metasurfaces

    PubMed Central

    Xu, He-Xiu; Sun, Shulin; Tang, Shiwei; Ma, Shaojie; He, Qiong; Wang, Guang-Ming; Cai, Tong; Li, Hai-Peng; Zhou, Lei

    2016-01-01

    Manipulating the polarization states of electromagnetic (EM) waves, a fundamental issue in optics, attracted intensive attention recently. However, most of the devices realized so far are either too bulky in size, and/or are passive with only specific functionalities. Here we combine theory and experiment to demonstrate that, a tunable metasurface incorporating diodes as active elements can dynamically control the reflection phase of EM waves, and thus exhibits unprecedented capabilities to manipulate the helicity of incident circular-polarized (CP) EM wave. By controlling the bias voltages imparted on the embedded diodes, we demonstrate that the device can work in two distinct states. Whereas in the “On” state, the metasurface functions as a helicity convertor and a helicity hybridizer within two separate frequency bands, it behaves as a helicity keeper within an ultra-wide frequency band in the “Off” state. Our findings pave the way to realize functionality-switchable devices related to phase control, such as frequency-tunable subwavelength cavities, anomalous reflectors and even holograms. PMID:27272350

  10. Synthesis of Numerical Methods for Modeling Wave Energy Converter-Point Absorbers: Preprint

    SciTech Connect

    Li, Y.; Yu, Y. H.

    2012-05-01

    During the past few decades, wave energy has received significant attention among all ocean energy formats. Industry has proposed hundreds of prototypes such as an oscillating water column, a point absorber, an overtopping system, and a bottom-hinged system. In particular, many researchers have focused on modeling the floating-point absorber as the technology to extract wave energy. Several modeling methods have been used such as the analytical method, the boundary-integral equation method, the Navier-Stokes equations method, and the empirical method. However, no standardized method has been decided. To assist the development of wave energy conversion technologies, this report reviews the methods for modeling the floating-point absorber.

  11. Fundamental emission via wave advection from a collapsing wave packet in electromagnetic strong plasma turbulence

    SciTech Connect

    Jenet, F. A.; Melatos, A.; Robinson, P. A.

    2007-10-15

    Zakharov simulations of nonlinear wave collapse in continuously driven two-dimensional, electromagnetic strong plasma turbulence with electron thermal speeds v{>=}0.01c show that for v < or approx. 0.1c, dipole radiation occurs near the plasma frequency, mainly near arrest, but for v > or approx. 0.1c, a new mechanism applies in which energy oscillates between trapped Langmuir and transverse modes until collapse is arrested, after which trapped transverse waves are advected into incoherent interpacket turbulence by an expanding annular density well, where they detrap. The multipole structure, Poynting flux, source current, and radiation angular momentum are computed.

  12. Electromagnetic Wave Propagation Through the ZR Z-Pinch Accelerator

    SciTech Connect

    Rose, D. V.; Welch, D. R.; Madrid, E. A.; Miller, C. L.; Clark, R. E.; Stygar, W. A.; Struve, K.; Corcoran, P. A.; Whitney, B.

    2009-01-21

    A fully three-dimensional electromagnetic model of the major pulsed power components of the 26-MA ZR accelerator is presented. This large-scale simulation model tracks the evolution of electromagnetic waves through the intermediate storage capacitors, laser-triggered gas switches, pulse-forming lines, water switches, tri-plate transmission lines, and water convolute to the vacuum insulator stack. The plates at the insulator stack are coupled to a transmission line circuit model of the four-level magnetically-insulated transmission line section and post-hole convolutes. The vacuum section circuit model is terminated by either a short-circuit load or dynamic models of imploding z-pinch loads. The simulations results are compared with electrical measurements made throughout the ZR accelerator and good agreement is found, especially for times before and up to peak load power. This modeling effort represents new opportunities for modeling existing and future large-scale pulsed power systems used in a variety of high energy density physics and radiographic applications.

  13. Electromagnetic plasma wave emissions from the auroral field lines

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1977-01-01

    The most important types of auroral radio emissions are reviewed, both from a historical perspective as well as considering the latest results. Particular emphasis is placed on four types of electromagnetic emissions which are directly associated with the plasma on the auroral field lines. These emissions are (1) auroral hiss, (2) saucers, (3) ELF noise bands, and (4) auroral kilometric radiation. Ray tracing and radio direction finding measurements indicate that both the auroral hiss and auroral kilometric radiation are generated along the auroral field lines relatively close to the earth, at radial distances from about 2.5 to 5 R sub e. For the auroral hiss the favored mechanism appears to be amplified Cerenkov radiation. For the auroral kilometric radiation several mechanisms have been proposed, usually involving the intermediate generation of electrostatic waves by the precipitating electrons.

  14. Identifying Electromagnetic Counterparts to Gravitational Wave Triggers With DECam

    NASA Astrophysics Data System (ADS)

    Cowperthwaite, Philip

    2016-03-01

    Identifying the electromagnetic counterpart to a gravitational wave (GW) event is one of the great observational challenges in modern astronomy. We report on our work to overcome this challenge by investigating the theoretical and practical issues associated with optical follow-up of a GW event. This includes a systematic study of the potential contaminant population and their impact on counterpart detectability in simulated observations. Additionally, we utilize data taken with the Dark Energy Camera (DECam) on the Blanco 4-m telescope at CTIO. These data serve as a mock follow-up to a GW event and assist in the characterization of contamination not captured in simulations. P.S.C. is grateful for support provided by the NSF through the Graduate Research Fellowship Program, Grant DGE1144152.

  15. Heating of the plasma sheet by broadband electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Chaston, C. C.; Bonnell, J. W.; Salem, C.

    2014-12-01

    We demonstrate that broadband low-frequency electromagnetic field fluctuations embedded within fast flows throughout the Earth's plasma sheet may drive significant ion heating. This heating is nearly entirely in the direction perpendicular to the background magnetic field and is estimated to occur at an average rate of ~1 eV/s with rates in excess of 10 eV/s within one standard deviation of the average value over all observed events. For an Earthward flow the total change in temperature along a flow path may exceed one keV and for "wave-rich" flows can be comparable to that expected due to conservation of the first adiabatic invariant. The consequent increase in plasma pressure and flux tube entropy may lead to braking of inward motion and the suppression of plasma interchange.

  16. Searches for electromagnetic signatures of gravitational wave sources

    NASA Astrophysics Data System (ADS)

    Soares-Santos, Marcelle

    2017-01-01

    Motivated by the exciting prospect of new wealth of information that will arise from observations of gravitational and electromagnetic radiation from the same astrophysical phenomena, our community has performed a broad range of follow-up programs for LIGO/Virgo events. In this talk, I present an overview of this effort, including results of searches for signatures of the first two LIGO-triggered binary black hole mergers in the 2015-2016 observing campaign, when multiple facilities reported searches in gamma/X-rays, optical, infra-red, and radio wavelengths. I will also discuss plans for upcoming observing campaigns and long term prospects for this exciting emerging field: multi-messenger astrophysics with gravitational waves.

  17. High-informative version of nonlinear transformation of Langmuir waves to electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Erofeev, Vasily I.; Erofeev

    2014-04-01

    The concept of informativeness of nonlinear plasma physical scenario is discussed. Basic principles for heightening the informativeness of plasma kinetic models are explained. Former high-informative correlation analysis of plasma kinetics (Erofeev, V. 2011 High-Informative Plasma Theory, Saarbrücken: LAP) is generalized for studies of weakly turbulent plasmas that contain fields of solenoidal plasma waves apart from former potential ones. Respective machinery of plasma kinetic modeling is applied to an analysis of fusion of Langmuir waves with transformation to electromagnetic waves. It is shown that the customary version of this phenomenon (Terashima, Y. and Yajima, N. 1963 Prog. Theor. Phys. 30, 443; Akhiezer, I. A., Danelia, I. A. and Tsintsadze, N. L. 1964 Sov. Phys. JETP 19, 208; Al'tshul', L. M. and Karpman, V. I. 1965 Sov. Phys. JETP 20, 1043) substantially distorts the picture of merging of Langmuir waves with long wavelengths (λ >~ c/ωpe ).

  18. A novel CFS-PML boundary condition for transient electromagnetic simulation using a fictitious wave domain method

    NASA Astrophysics Data System (ADS)

    Hu, Yanpu; Egbert, Gary; Ji, Yanju; Fang, Guangyou

    2017-01-01

    In this study, we apply fictitious wave domain (FWD) methods, based on the correspondence principle for the wave and diffusion fields, to finite difference (FD) modeling of transient electromagnetic (TEM) diffusion problems for geophysical applications. A novel complex frequency shifted perfectly matched layer (PML) boundary condition is adapted to the FWD to truncate the computational domain, with the maximum electromagnetic wave propagation velocity in the FWD used to set the absorbing parameters for the boundary layers. Using domains of varying spatial extent we demonstrate that these boundary conditions offer significant improvements over simpler PML approaches, which can result in spurious reflections and large errors in the FWD solutions, especially for low frequencies and late times. In our development, resistive air layers are directly included in the FWD, allowing simulation of TEM responses in the presence of topography, as is commonly encountered in geophysical applications. We compare responses obtained by our new FD-FWD approach and with the spectral Lanczos decomposition method on 3-D resistivity models of varying complexity. The comparisons demonstrate that our absorbing boundary condition in FWD for the TEM diffusion problems works well even in complex high-contrast conductivity models.

  19. Application of electromagnetic waves in damage detection of concrete structures

    NASA Astrophysics Data System (ADS)

    Feng, Maria Q.; De Flaviis, Franco; Kim, Yoo J.; Diaz, Rodolfo E.

    2000-04-01

    Jacketing technology using fiber reinforced polymer (FRP) composites is being applied for seismic retrofit of reinforced concrete (RC) columns designed and constructed under older specifications. In this study, the authors develop an electromagnetic (EM) imaging technology for detecting voids and debonding between the jacket and the column, which may significantly weaken the structural performance of the column otherwise attainable by jacketing. This technology is based on the reflection analysis of a continuous EM wave sent toward and reflected from layered FRP-adhesive-concrete medium: Poor bonding conditions including voids and debonding will generate air gaps which produce additional reflections of the EM wave. In this study, dielectric properties of various materials involved in the FRP-jacketed RC column were first measured. Second, the measured properties were used for a computer simulation of the proposed EM imaging technology. The simulation demonstrated the difficulty in detecting imperfect bonding conditions by using plane waves, as the scattering contribution from the voids and debonding is very small compared to that from the jacketed column. Third, in order to alleviate this difficulty, a special dielectric lens was designed and fabricated to focus the EM wave on the bonding interface. Furthermore, the time gating technique is used in order to reduce the noise resulting from various uncertainties associated with the jacketed columns. Finally, three concrete columns were constructed and wrapped with glass-FRP jackets with various voids and debonding condition artificially introduced in the bonding interface. Using the proposed EM imaging technology with the lens especially designed and installed, these voids and debonding condition were successfully detected.

  20. The spartial distribution of the particles of the beam interacting with an inhomogeneous electromagnetic wave

    SciTech Connect

    Serov, A.V.

    1995-12-31

    The time variation of the spartial distribution of an electron beam reflected by an inhomogeneous wave or traverse the wave was investigated. The injected beam is perpendicular to the direction of propagation of the wave. The interaction between an electron beam and an electromagnetic wave not only produces electron oscillation but also substantially changes the electron phase and energy distribution. It is shown that under specific conditions one part of particles are reflected by an electromagnetic wave and other part of particles traverse the wave.

  1. Parametric study of two-body floating-point wave absorber

    NASA Astrophysics Data System (ADS)

    Amiri, Atena; Panahi, Roozbeh; Radfar, Soheil

    2016-03-01

    In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber (FPA) with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter's efficiency when considering specific conditions.

  2. Electromagnetic Waves and Bursty Electron Acceleration: Implications from Freja

    NASA Technical Reports Server (NTRS)

    Andersson, Laila; Ivchenko, N.; Wahlund, J.-E.; Clemmons, J.; Gustavsson, B.; Eliasson, L.

    2000-01-01

    Dispersive Alfven wave activity is identified in four dayside auroral oval events measured by the Freja satellite. The events are characterized by ion injection, bursty electron precipitation below about I keV, transverse ion heating and broadband extremely low frequency (ELF) emissions below the lower hybrid cutoff frequency (a few kHz). The broadband emissions are observed to become more electrostatic towards higher frequencies. Large-scale density depletions/cavities, as determined by the Langmuir probe measurements, and strong electrostatic emissions are often observed simultaneously. A correlation study has been carried out between the E- and B-field fluctuations below 64 Hz (the dc instrument's upper threshold) and the characteristics of the precipitating electrons. This study revealed that the energization of electrons is indeed related to the broadband ELF emissions and that the electrostatic component plays a predominant role during very active magnetospheric conditions. Furthermore, the effect of the ELF electromagnetic emissions on the larger scale field-aligned current systems has been investigated, and it is found that such an effect cannot be detected. Instead, the Alfvenic activity creates a local region of field-aligned currents. It is suggested that dispersive Alfven waves set up these local field-aligned current regions and in turn trigger more electrostatic emissions during certain conditions. In these regions ions are transversely heated, and large-scale density depletions/cavities may be created during especially active periods.

  3. Seismo-Electromagnetic Emissions Related to Seismic Waves can Trigger TLEs

    SciTech Connect

    Sorokin, Leonid V.

    2009-04-27

    This paper deals with the rare high intensity electromagnetic pulses associated with earthquakes, whose spectrum signature differs from that of atmospherics produced by lightning discharges. On the basis of actual data records, cases of the generation of anomalous seismo-electromagnetic emissions are described. These natural sub-millisecond electromagnetic pulses were associated with the passage of seismic waves from earthquakes to Moscow, the place where the electromagnetic field observations were made. Space-time coupling has been revealed between exact seismic waves from the earthquakes, lightning triggering and Transient Luminous Events triggering.

  4. Properties of electrons scattered by a strong plane electromagnetic wave with a linear polarization: Semiclassical treatment

    NASA Astrophysics Data System (ADS)

    Bogdanov, O. V.; Kazinski, P. O.

    2015-02-01

    The problem of scattering of ultrarelativistic electrons by a strong plane electromagnetic wave of a low (optical) frequency and linear polarization is solved in the semiclassical approximation, when the electron wave packet size is much smaller than the wavelength of electromagnetic wave. The exit momenta of ultrarelativistic electrons scattered are found using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of electrons traversed the electromagnetic wave depend weakly on the initial values of momenta. These electrons are mostly scattered at small angles to the propagation direction of the electromagnetic wave. The maximum Lorentz factor of electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momentum. The momentum component parallel to the electric field vector of the electromagnetic wave is determined solely by the laser beam diameter measured in the units of the classical electron radius. As for the reflected electrons, they for the most part lose the energy, but remain relativistic. A reflection law that relates the incident and reflection angles and is independent of any parameters is found.

  5. Risk perception and public concerns of electromagnetic waves from cellular phones in Korea.

    PubMed

    Kim, Kyunghee; Kim, Hae-Joon; Song, Dae Jong; Cho, Yong Min; Choi, Jae Wook

    2014-05-01

    In this study, the difference between the risk perception of electromagnetic waves from cellular phones and the risk perception of other factors such as environment and food was analyzed. The cause of the difference in the psychological and social factors that affect the group with high risk perception of electromagnetic waves was also analyzed. A questionnaire survey on the risk perception of electromagnetic waves from cellular phones was carried out on 1001 subjects (men and women) over the age of 20. In the group with high risk perception of electromagnetic waves from cellular phones, women had higher risk perception than men. Logistic regression analysis, where the group with high risk perception of electromagnetic waves and the group with low risk perception were used as dependent variables, indicated that the risk perception of electromagnetic waves in women was 1.815 times statistically significantly higher than the risk perception of men (95% CI: 1.340-2.457). Also, high risk perception of electromagnetic waves from cellular phones was observed when the subjects considered that they had more personal knowledge (OR: 1.416, 95% CI: 1.216-1.648), that the seriousness of the risk to future generations was high (OR: 1.410, 95% CI: 1.234-1.611), and their outrage for the occurrence of accidents related to electromagnetic waves was high (OR: 1.460, 95% CI: 1.264-1.686). The results of this study need to be sufficiently considered and reflected in designing the risk communication strategies and communication methods for the preventive measures and advice on electromagnetic waves from cellular phones.

  6. What is the impact of electromagnetic waves on epileptic seizures?

    PubMed Central

    Cinar, Nilgun; Sahin, Sevki; Erdinc, Oguz O.

    2013-01-01

    Background The effects of electromagnetic waves (EMWs) on humans and their relationship with various disorders have been investigated. We aimed to investigate the effects of exposure to different frequencies of EMWs in various durations in a mouse epilepsy model induced by pentylenetetrazole (PTZ). Material/Methods A total of 180 4-week-old male mice weighing 25–30 g were used in this study. Each experimental group consisted of 10 mice. They were exposed to 900, 700, 500, 300, and 100 MHz EMWs for 20 hours, 12 hours and 2 hours. Following electromagnetic radiation exposure, 60 mg/kg of PTZ was injected intraperitoneally to all mice. Each control was also injected with PTZ without any exposure to EMW. The latency of initial seizure and most severe seizure onset were compared with controls. Results The shortest initial seizure latency was noted in the 12-hour group, followed by the 700 MHz. The mean initial seizure latencies in the 2-hour EMW exposed group was significantly shorter compared to that in the 12- and 20-hour groups. There was no significant difference between 12- and 20-hour EMW exposed groups. There was a significant difference between control and 2- and 10-hour EMW exposed groups. No statistically significant differences were noted in mean latencies of the most severe seizure latency, following 20-, 12-, and 2- hour EMW exposed groups and control groups. Conclusions Our findings suggest that acute exposure to EMW may facilitate epileptic seizures, which may be independent of EMW exposure time. This information might be important for patients with epilepsy. Further studies are needed. PMID:23676765

  7. Electromagnetic wave band structure due to surface plasmon resonances in a complex plasma

    NASA Astrophysics Data System (ADS)

    Vladimirov, S. V.; Ishihara, O.

    2016-07-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations can significantly modify plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The conditions necessary to observe the band-gap structure in laboratory dusty plasma and/or space (cosmic) dusty plasmas are discussed.

  8. Radiation of electromagnetic waves by a dipole in an external uniform electrostatic field

    NASA Astrophysics Data System (ADS)

    Manaenkov, S. I.

    2017-01-01

    Exact solution for the electromagnetic field densities E and H of a dipole of uniformly accelerated point-charges with identical masses is discussed. It is shown that, for any fixed time t and a large distance R between the center of the dipole and the fieldpoint, | E| R -4, | H| R -5, while for large c| t| R, | E| | H| 1/ R as in spherical electromagnetic waves. Nevertheless, any irreversible radiation of electromagnetic waves is absent since the wave zone does not exist.

  9. A review of nondestructive testing approaches using mechanical and electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Lau, Denvid; Qiu, Qiwen

    2016-04-01

    Mechanical and electromagnetic waves are commonly used in nondestructive testing (NDT) techniques for evaluating the materials and structures in civil engineering industry, due to their good examination of defects inside the matter. However, the individual use of mechanical wave or electromagnetic wave in NDT methods sometimes does not fulfill the satisfactory detection in practice because of the operational inconvenience and low sensitivity. It has been demonstrated that the combination of using both types of waves can achieve a better performance for NDT application and would be the future direction for defect detection, as the advantages of each physical wave are picked out whereas the weaknesses are mitigated. This paper discusses the fundamental mechanisms and the current applications of using mechanical and electromagnetic waves for defect detection, with the goal of providing the physical knowledge and the perspectives of developing the NDT applications with these two types of waves. Typical mechanical-wave-based NDT methods such as acoustic emission, ultrasonic technique, and impact-echo method are reviewed. In addition, NDT methods using electromagnetic wave, which include optical fiber sensing technique, laser speckle interferometry and laser reflection technique are discussed. Advantages and disadvantages of these methods are outlined. In particular, we focus on a recent NDT method called acoustic-laser technique, which utilizes both the mechanical and electromagnetic waves. The basic principles and some important experimental data recorded by the acoustic-laser technique are described and its future development in the field of defect detection in civil infrastructure is presented.

  10. Using photon funnels based on metamaterial cloaks to compress electromagnetic wave beams.

    PubMed

    Ma, Hua; Qu, Shaobo; Xu, Zhuo; Wang, Jiafu

    2008-08-10

    Based on the metamaterial cloaking technique, we propose the use of a new photon funnel to compress a plane electromagnetic (EM) wave. The theoretical analysis and numerical simulations indicate that the compression ratio can be designed optionally and the compressed wave beam remains the original wave shape without any distortions. Here we apply the method to EM waves but it can be applied to acoustic waves and other fields as well.

  11. Propagation and linear mode conversion of magnetosonic and electromagnetic ion cyclotron waves in the radiation belts

    NASA Astrophysics Data System (ADS)

    Horne, Richard B.; Miyoshi, Yoshizumi

    2016-10-01

    Magnetosonic waves and electromagnetic ion cyclotron (EMIC) waves are important for electron acceleration and loss from the radiation belts. It is generally understood that these waves are generated by unstable ion distributions that form during geomagnetically disturbed times. Here we show that magnetosonic waves could be a source of EMIC waves as a result of propagation and a process of linear mode conversion. The converse is also possible. We present ray tracing to show how magnetosonic (EMIC) waves launched with large (small) wave normal angles can reach a location where the wave normal angle is zero and the wave frequency equals the so-called crossover frequency whereupon energy can be converted from one mode to another without attenuation. While EMIC waves could be a source of magnetosonic waves below the crossover frequency, magnetosonic waves could be a source of hydrogen band waves but not helium band waves.

  12. A wave guide model of lightning currents and their electromagnetic field

    NASA Technical Reports Server (NTRS)

    Volland, H.

    1980-01-01

    Lightning channels are considered as resonant wave guides in which only standing resonant wave modes can be excited. Two types of discharging currents develop. Type 1 is an aperiodic wave; type 2 is a damped oscillation. The electromagnetic radiation field of both types of currents is calculated and compared with the observation.

  13. Excitation of surface electromagnetic waves in a graphene-based Bragg grating

    PubMed Central

    Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting

    2012-01-01

    Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc. PMID:23071901

  14. Effects of dissipation on propagation of surface electromagnetic and acoustic waves

    NASA Astrophysics Data System (ADS)

    Nagaraj, Nagaraj

    With the recent emergence of the field of metamaterials, the study of subwavelength propagation of plane waves and the dissipation of their energy either in the form of Joule losses in the case of electomagnetic waves or in the form of viscous dissipation in the case of acoustic waves in different interfaced media assumes great importance. With this motivation, I have worked on problems in two different areas, viz., plasmonics and surface acoustics. The first part (chapters 2 & 3) of the dissertation deals with the emerging field of plasmonics. Researchers have come up with various designs in an effort to fabricate efficient plasmonic waveguides capable of guiding plasmonic signals. However, the inherent dissipation in the form of Joule losses limits efficient usage of surface plasmon signal. A dielectric-metal-dielectric planar structure is one of the most practical plasmonic structures that can serve as an efficient waveguide to guide electromagnetic waves along the metal-dielectric boundary. I present here a theoretical study of propagation of surface plasmons along a symmetric dielectric-metal-dielectric structure and show how proper orientation of the optical axis of the anisotropic substrate enhances the propagation length. An equation for propagation length is derived in a wide range of frequencies. I also show how the frequency of coupled surface plasmons can be modulated by changing the thickness of the metal film. I propose a Kronig-Penny model for the plasmonic crystal, which in the long wavelength limit, may serve as a homogeneous dielectric substrate with high anisotropy which do not exist for natural optical crystals. In the second part (chapters 4 & 5) of the dissertation, I discuss an interesting effect of extraordinary absorption of acoustic energy due to resonant excitation of Rayleigh waves in a narrow water channel clad between two metal plates. Starting from the elastic properties of the metal plates, I derive a dispersion equation that gives

  15. Electromagnetic waves destabilized by runaway electrons in near-critical electric fields

    SciTech Connect

    Komar, A.; Pokol, G. I.; Fueloep, T.

    2013-01-15

    Runaway electron distributions are strongly anisotropic in velocity space. This anisotropy is a source of free energy that may destabilize electromagnetic waves through a resonant interaction between the waves and the energetic electrons. In this work, we investigate the high-frequency electromagnetic waves that are destabilized by runaway electron beams when the electric field is close to the critical field for runaway acceleration. Using a runaway electron distribution appropriate for the near-critical case, we calculate the linear instability growth rate of these waves and conclude that the obliquely propagating whistler waves are most unstable. We show that the frequencies, wave numbers, and propagation angles of the most unstable waves depend strongly on the magnetic field. Taking into account collisional and convective damping of the waves, we determine the number density of runaways that is required to destabilize the waves and show its parametric dependences.

  16. Locating voids beneath pavement using pulsed electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Steinway, W. J.; Echard, J. D.; Luke, C. M.

    1981-11-01

    The feasibility of using pulsed electromagnetic wave technology for locating and sizing voids beneath reinforced and nonreinforced portland cement concrete pavements is determined. The data processing techniques developed can be implemented to provide information for void depth and sizing to + or - 1/2 in. and spatial location within + or - 6 in. A very short pulse radar directly connected to a microcomputer was chosen as the equipment necessary to obtain measurements. This equipment has the required accuracy and reliability, and is a cost effective solution for the void locating problem. The radar provides a signal return from voids that has unique characteristics that can be examined to provide information regarding the location, depth, and shape of the void. The microcomputer provides a means of real time processing to extract the information from the radar signal return and record the results. Theoretical modeling of signal returns from voids led to suitable techniques for locating and sizing voids beneath the pavement. Analysis and application of these techniques to radar measurements verified the theoretical predictions that radar can be used to determine the location, size, and shape of actual voids.

  17. Propagation of Electromagnetic Waves in Two Dimensionally Periodic Media

    NASA Astrophysics Data System (ADS)

    Dong, Tian-Lin

    1985-12-01

    The propagation of electromagnetic waves in two dimensionally periodic structure is systematically investigated, to provide the basic theory for two dimensionally modulated dielectric waveguide. A canonical two dimensionally periodic medium of infinite extent, whose dielectic constant varies sinusoidally in two orthogonal directions, is first examined. The charact solutions are represented exactly by a double Fourier series which is known as the Floquet solution. The harmonic amplitudes of the Floquet solution are determined by a five-term recurrence relation in the vector form, properly taking into account the hybrid-mode nature of the propagation problem. The five-term recurrence relation is then treated by different approaches so that clear physical pictures and practical numerical methods can be obtained. The characteristic solutions for two dimensionally periodic medium are then applied to the boundary-value problem of multi-layer dielectric waveguides containing a finite layer of periodic medium. As an example, the guidance problems are analysed and the numerical analysis of the dispersion characteristics are then carried out. Besides the canonical medium as a model, more general two dimensionally periodic medium are also discussed.

  18. A selective pyroelectric detector of millimeter-wave radiation with an ultrathin resonant meta-absorber

    NASA Astrophysics Data System (ADS)

    Paulish, A. G.; Kuznetsov, S. A.

    2016-11-01

    The results of experimental investigations of spectral and amplitude-frequency characteristics for a discrete wavelength-selective pyroelectric detector operating in the millimetric band are presented. The high spectral selectivity is attained due to integrating the detector with a resonant meta-absorber designed for a close-to-unity absorptivity at 140 GHz. It is demonstrated that the use of this meta-absorber provides an opportunity to construct small-sized and inexpensive multispectral polarization-sensitive systems for radiation detection in the range of millimeter and submillimeter waves.

  19. Electromagnetic-wave excitation in a large laboratory beam-plasma system

    NASA Technical Reports Server (NTRS)

    Whelan, D. A.; Stenzel, R. L.

    1981-01-01

    The mechanism by which unstable electrostatic waves of a beam-plasma system are converted into observed electromagnetic waves is of current interest in space physics and in tokamak fusion research. The process involved in the conversion of electrostatic to electromagnetic waves at the critical layer is well understood. However, the radiation from uniform plasmas cannot be explained on the basis of this process. In connection with certain difficulties, it has not yet been possible to establish the involved emission processes by means of experimental observations. In the considered investigation these difficulties are overcome by employing a large laboratory plasma in a parameter range suitable for detailed diagnostics. A finite-diameter electron beam is injected into a uniform quiescent afterglow plasma of dimensions large compared with electromagnetic wavelengths. The considered generation mechanism concerning the electromagnetic waves is conclusively confirmed by observing the temporal evolution of an instability

  20. Interaction of Charged Particles with Ultra Strong Electromagnetic Waves in the Radiation Dominant Regime

    NASA Astrophysics Data System (ADS)

    Bulanov, S. V.; Esirkepov, T. Zh.; Koga, J.; Tajima, T.

    2004-10-01

    The plasma particle interaction with a relativistically intense electromagnetic wave under the conditions when the radiation reaction effects are dominant is considered. We analyze the radiation damping effects on the electron motion inside the circularly polarized planar wave and inside a subcycle crossed-field electromagnetic pulse. We consider the ion acceleration due to the radiation pressure action on a thin plasma slab. The results of 2D and 3D PIC simulations are presented.

  1. Influence of strong field vacuum polarization on gravitational-electromagnetic wave interaction

    SciTech Connect

    Forsberg, M.; Brodin, G.; Papadopoulos, D.

    2010-07-15

    The interaction between gravitational and electromagnetic waves in the presence of a static magnetic field is studied. The field strength of the static field is allowed to surpass the Schwinger critical field, such that the QED effects of vacuum polarization and magnetization are significant. Equations governing the interaction are derived and analyzed. It turns out that the energy conversion from gravitational to electromagnetic waves can be significantly altered due to the QED effects. The consequences of our results are discussed.

  2. Characterization of porous construction materials using electromagnetic radar wave

    NASA Astrophysics Data System (ADS)

    Lai, Wallace Wai Lok

    This thesis reports the effort of characterizing three porous construction materials (i.e. concrete, asphalt and soils) and the establishment and formulation of novel unified constitutive models by utilizing electromagnetic (EM) radar wave. An important outcome of this research is that the studied materials were assigned successfully into their rightful positions corresponding to the different regimes governed by three EM wave properties and two engineering/geological properties of the materials. The former refers to the real part of complex dielectric permittivity (epsilon'), energy attenuation and peak-frequency drift. The latter refers to porosity and permeability determined with forward models or conventional testing techniques. In soil and asphalt, the material characterization was achieved by a novel inhouse developed method called Cyclic Moisture Variation Technique (CMVT). The technique is termed cyclic because the porous materials were subjected to change from partially saturated states to fully saturated state (i.e. permeation), and vice versa (i.e. de-watering). With CMVT, water was used as an enhancer or a tracer to differentiate the studied materials which are otherwise difficult when they are dry. Soils and asphalt with different textures were characterized by different curve families exhibited in the relationship between epsilon' and degrees of water saturation (SW). In particular, these curve families were divided into three regions: slow-climbing region in very low SW, fast-climbing region in intermediate SW and another slow-climbing region at high S W. When data obtained from the permeation and de-watering cycles was compared, dielectric hysteresis was observed, but rarely reported in the field of ground penetrating radar (GPR). Different curing histories affect both porosity and pore size distribution within mature concrete. By injecting pressurized water into concrete specimens, different concrete curing histories was back-tracked through the

  3. Analysis and measurement of electromagnetic scattering by pyramidal and wedge absorbers

    NASA Technical Reports Server (NTRS)

    Dewitt, B. T.; Burnside, Walter D.

    1986-01-01

    By modifying the reflection coefficients in the Uniform Geometrical Theory of Diffraction a solution that approximates the scattering from a dielectric wedge is found. This solution agrees closely with the exact solution of Rawlins which is only valid for a few minor cases. This modification is then applied to the corner diffraction coefficient and combined with an equivalent current and geometrical optics solutions to model scattering from pyramid and wedge absorbers. Measured results from 12 inch pyramid absorbers from 2 to 18 GHz are compared to calculations assuming the returns add incoherently and assuming the returns add coherently. The measured results tend to be between the two curves. Measured results from the 8 inch wedge absorber are also compared to calculations with the return being dominated by the wedge diffraction. The procedures for measuring and specifying absorber performance are discussed and calibration equations are derived to calculate a reflection coefficient or a reflectivity using a reference sphere. Shaping changes to the present absorber designs are introduced to improve performance based on both high and low frequency analysis. Some prototypes were built and tested.

  4. Electromagnetic and absorbing property of CIPs/resin composite using the 3D forming process

    NASA Astrophysics Data System (ADS)

    Xu, Yonggang; Liang, Zichang; Wang, Xiaobing; Yuan, Liming; Li, Xinghao

    2016-08-01

    The absorbing composite filled with the flaky carbonyl iron particles (CIPs) were prepared using a three-dimensional (3D) forming process, in which the forming powder was fabricated using a milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer, and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 4-18 GHz. With the variable thickness was set, the reflection loss (RL) was simulated to analyze the absorbing property of the composite. The results showed that the forming powder was uniformly dispersed in the absorber, and the saturation magnetization and the grain structure of the CIPs in the forming powder nearly did not change in the milling process. With the same volume content CIPs added, the average permittivity and the imaginary permeability of the samples added the powder was smaller than the directly mixing sample due to the aggregation effect. The RL results showed that the absorbing composites using the 3D forming process with thickness 6 or 8 mm had an better absorbing property (minimum RL -13.58 and -21.85 dB) in 4-18 GHz.

  5. Electromagnetic property of SiO2-coated carbonyl iron/polyimide composites as heat resistant microwave absorbing materials

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-02-01

    Heat resistant microwave absorbing materials were prepared by compression molding method, using polyimide resin as matrix and SiO2 coated carbonyl iron (CI) as filler. The SiO2 coated CI particles were prepared by Stober process. The microwave absorbing properties and the effect of heat treatment on the electromagnetic properties of SiO2 coated CI/polyimide composites were investigated. When the content of SiO2 coated CI is 60 wt%, the value of minimum reflection loss decreases from -25 dB to -33 dB with the thickness increases from 1.5 mm to 2.1 mm. According to the thermal-gravimetric analyses (TGA) curves, the polyimide matrix can be used at 300 °C for long time. The complex permittivity of the composites slightly increases while the complex permeability almost keeps constant after heat treatment at 300 °C for 10 h, which indicating that the composites can be used at elevated temperature as microwave absorbing materials at the same time have good heat resistance and microwave absorption.

  6. Excitation of Rossby waves by HF electromagnetic seismic origin emissions in the earth's mesosphere

    NASA Astrophysics Data System (ADS)

    Tsintsadze, N. L.; Kaladze, T. D.; Tsamalashvili, L. V.

    2009-12-01

    Interaction of high-frequency seismo-electromagnetic emissions with the weakly ionized gas of the ionospheric D-layer is considered. It is shown that through the earth's ionosphere weakly damped high-frequency electron cyclotron electromagnetic waves can propagate. These new type of waves easily reach the ionospheric D-layer where they interact with the existing electrons and ions. Acting on electrons ponderomotive force is taken into account and corresponding modified Charney equation is obtained. It is shown that only nonlinear vortical structures with negative vorticity (anticyclone) can be excited. The amplitude modulation of electromagnetic waves can lead to the excitation of Rossby waves in the weakly ionized gas. The corresponding growth rate is defined. Depending on the intensity of the pumping waves generated by seismic activity different stable and unstable branches of oscillations are found. Detection of the new oscillation branches and energetically reinforcing Rossby solitary vortical anticyclone structures may be serve as precursors to earthquake.

  7. Experimental demonstration of a transparent graphene millimetre wave absorber with 28% fractional bandwidth at 140 GHz

    PubMed Central

    Wu, Bian; Tuncer, Hatice M.; Naeem, Majid; Yang, Bin; Cole, Matthew T.; Milne, William I.; Hao, Yang

    2014-01-01

    The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125–165 GHz. Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance. PMID:24549254

  8. Generation Mechanism and Propagation Features of the Ionospheric Weather Forming ULF Electromagnetic Wave Structures

    NASA Astrophysics Data System (ADS)

    Aburjania, G. D.; Chargazia, Kh. Z.; Khantadze, A. G.; Lominadze, J. G.

    2006-12-01

    Results of theoretical investigation of the dynamics of generation and propagation of planetary (with wavelengths 103 km and more) weather-forming Ultra-Low Frequency (ULF) electromagnetic wave structures in the dissipative ionosphere are given in this paper. It is established that the global factor, acting permanently in the ionosphere spatial inhomogeneity and curvature of the geomagnetic field and inhomogeneity of angular velocity of the Earth's rotation generates the fast and slow planetary ULF electromagnetic waves. The waves propagate along the parallels to the east as well as to the west. In the E-region the fast waves have phase velocities of (2-20) km/s-1 and frequencies of (10^-1-10^-4) Hz; the slow waves propagate with local wind velocities and have frequencies (10^-4-10^-6) Hz. In the F-region the fast ULF electromagnetic waves propagate with phase velocities of tens-hundreds km/s-1 and their frequencies are in the range of (10-10^-3) Hz. The large-scale waves are weakly damped. The waves generate the geomagnetic field perturbations from several tens to several hundreds nT and more. It is established that planetary ULF electromagnetic waves, at their interaction with the local shear winds, can self-localize in the form of nonlinear solitary vortices, moving along the latitude circles westward as well as eastward.

  9. Boundary integral equation method for electromagnetic and elastic waves

    NASA Astrophysics Data System (ADS)

    Chen, Kun

    In this thesis, the boundary integral equation method (BIEM) is studied and applied to electromagnetic and elastic wave problems. First of all, a spectral domain BIEM called the spectral domain approach is employed for full wave analysis of metal strip grating on grounded dielectric slab (MSG-GDS) and microstrips shielded with either perfect electric conductor (PEC) or perfect magnetic conductor (PMC) walls. The modal relations between these structures are revealed by exploring their symmetries. It is derived analytically and validated numerically that all the even and odd modes of the latter two (when they are mirror symmetric) find their correspondence in the modes of metal strip grating on grounded dielectric slab when the phase shift between adjacent two unit cells is 0 or pi. Extension to non-symmetric case is also made. Several factors, including frequency, grating period, slab thickness and strip width, are further investigated for their impacts on the effective permittivity of the dominant mode of PEC/PMC shielded microstrips. It is found that the PMC shielded microstrip generally has a larger wave number than the PEC shielded microstrip. Secondly, computational aspects of the layered medim doubly periodic Green's function (LMDPGF) in matrix-friendly formulation (MFF) are investigated. The MFF for doubly periodic structures in layered medium is derived, and the singularity of the periodic Green's function when the transverse wave number equals zero in this formulation is analytically extracted. A novel approach is proposed to calculate the LMDPGF, which makes delicate use of several techniques including factorization of the Green's function, generalized pencil of function (GPOF) method and high order Taylor expansion to derive the high order asymptotic expressions, which are then evaluated by newly derived fast convergent series. This approach exhibits robustness, high accuracy and fast and high order convergence; it also allows fast frequency sweep for

  10. Generation of a longitudinal current upon interaction of a transverse electromagnetic wave with degenerate plasma

    NASA Astrophysics Data System (ADS)

    Latyshev, A. V.; Yushkanov, A. A.

    2017-02-01

    We consider degenerate plasma that is located in the field of a transverse electromagnetic wave. An electric current generated in the plasma by the electromagnetic field is sought. During classical description of the interaction of the electromagnetic wave with the plasma, the Vlasov kinetic equation is used, while, in quantum description, the quantum kinetic equation with the Wigner integral is applied. A nonlinear analysis has shown that that the electric current in the plasma has two nonzero components. One component of the electric current is directed along the vector potential of the electromagnetic field. The other nonzero component of the current is directed along the wave vector. In the present work, we analyze this component of the electric current. The case of collisionless plasma is examined.

  11. TE and TM beam decomposition of time-harmonic electromagnetic waves.

    PubMed

    Melamed, Timor

    2011-03-01

    The present contribution is concerned with applying beam-type expansion to planar aperture time-harmonic electromagnetic field distribution in which the propagating elements, the electromagnetic beam-type wave objects, are decomposed into transverse electric (TE) and transverse magnetic (TM) field constituents. This procedure is essential for applying Maxwell's boundary conditions for solving different scattering problems. The propagating field is described as a discrete superposition of tilted and shifted TE and TM electromagnetic beams over the frame-based spatial-directional expansion lattice. These vector wave objects are evaluated either by applying differential operators to scalar beam propagators, or by using plane-wave spectral representations. Explicit asymptotic expressions for scalar, as well as for electromagnetic, Gaussian beam propagators are presented as well.

  12. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    PubMed Central

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-01-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed. PMID:27320212

  13. Elastic metamaterials for tuning circular polarization of electromagnetic waves.

    PubMed

    Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

    2016-06-20

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  14. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-06-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  15. Minimizing influence of multi-modes and dispersion of electromagnetic ultrasonic lamb waves.

    PubMed

    Zhai, Guofu; Jiang, Tao; Kang, Lei; Wang, Shujuan

    2010-12-01

    Electromagnetic ultrasonic (EMU) Lamb waves excited by electromagnetic acoustic transducers (EMATs) possess many advantages in NDT. However, their characteristic multi-modes and dispersion are disadvantageous for inspection and restrict further improvements in their real applications. By deducing the excitation equation of EMU Lamb waves, the primary design parameters of EMATs and the characteristic equation of Lamb waves are combined, and excitation curves based on the excitation equation are plotted to aid the design of EMATs. The excitation characteristic of EMU Lamb waves on different thickness of plates is analyzed according to the excitation curves. The influence of multi-modes of EMU Lamb waves is minimized by choosing reasonable operating points and operating zones to excite a single-mode Lamb wave or multi-mode Lamb waves with identical or approximate propagation velocities. The influence of dispersion is minimized by searching corresponding points whose slope of group velocity tends to zero. The validity of the proposed method is verified by experiments.

  16. Stimulated scattering of a large amplitude electromagnetic wave by the eigenmodes of a plasma slab

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1983-08-01

    New results are presented from a theoretical investigation of the scattering of an electromagnetic pump wave that is normally incident on a plasma slab. In the case considered here, the leaking surface wave eigenmode represents the scattered radiation. The generation of harmonics in the scattered wave will thus be responsible for the saturation of the wave intensities. It is shown that a large-amplitude electromagnetic pump wave can be scattered in a nonlinear process where both the low-frequency and high-frequency oscillations are eigenmodes of the plasma slab. The second harmonic generation that occurs in this case leads to efficient saturation of the scattering instability. It is pointed out that other mechanisms, for example, the screening of the pump wave by the surface mode current, may also contribute significantly to the establishment of the stationary wave.

  17. High temperature electromagnetic and microwave absorbing properties of polyimide/multi-walled carbon nanotubes nancomposites

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-07-01

    Multi-walled carbon nanotubes (MWCNTs) were introduced into polyimide matrix to fabricate high temperature microwave absorbing materials. The flexural strength can reach 125 MPa with 2 wt% MWCNTs, and the flexural strength decreases with increasing the filler content due to the filler reinforcement. The complex permittivity of the nanocomposite increases with increasing the temperature owing to shorten the relaxation time and enhance the electrical conductivity at elevated temperature. When the content of absorbent is 5%, the -10 dB absorption bandwidth could reach 1.3 GHz, with the thickness of 2.1 mm, while the bandwidth below -10 dB is 2.04 GHz with the thickness of 1.7 mm at 373 K.

  18. Electromagnetic Waves with Frequencies Near the Local Proton Gryofrequency: ISEF-3 1 AU Observations

    NASA Technical Reports Server (NTRS)

    Tsurutani, B.

    1993-01-01

    Low Frequency electromagnetic waves with periods near the local proton gyrofrequency have been detected near 1 AU by the magnetometer onboard ISEE-3. For these 1 AU waves two physical processes are possible: solar wind pickup of nuetral (interstellar?) particles and generation by relativistic electron beams propagating from the Sun.

  19. Teaching the Common Aspects in Mechanical, Electromagnetic and Quantum Waves at Interfaces and Waveguides

    ERIC Educational Resources Information Center

    Rojas, R.; Robles, P.

    2011-01-01

    We discuss common features in mechanical, electromagnetic and quantum systems, supporting identical results for the transmission and reflection coefficients of waves arriving perpendicularly at a plane interface. Also, we briefly discuss the origin of special notions such as refractive index in quantum mechanics, massive photons in wave guides and…

  20. The Relativistic Transformation for an Electromagnetic Plane Wave with General Time Dependence

    ERIC Educational Resources Information Center

    Smith, Glenn S.

    2012-01-01

    In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which…

  1. Group delay of electromagnetic pulses through multilayer dielectric mirrors combined with gravitational wave.

    PubMed

    Liu, J T; Wu, X; Liu, N H; Li, J; Su, F H

    2013-07-01

    Group delay of electromagnetic pulses through multilayer dielectric mirrors (MDM) combined with gravitational wave (GW) is investigated. Unlike in traditional quantum tunneling, the group delay of a transmitted wave packet irradiated by a GW increases linearly with MDM length. This peculiar tunneling effect can be attributed to electromagnetic wave leakage in a time-dependent photonic bandgap caused by the GW. In particular, we find that the group delay of the tunneling photons is sensitive to GW. Our study provides insight into the nature of the quantum tunnelling as well as a novel process by which to detect the GW.

  2. Dispersion characteristics of spin-electromagnetic waves in planar multiferroic structures

    SciTech Connect

    Nikitin, Andrey A.; Ustinov, Alexey B.; Vitko, Vitaliy V.; Semenov, Alexander A.; Mironenko, Igor G.; Belyavskiy, Pavel Yu.; Kalinikos, Boris A.; Stashkevich, Andrey A.; Lähderanta, E.

    2015-11-14

    A method of approximate boundary conditions is used to derive dispersion relations for spin-electromagnetic waves (SEWs) propagating in thin ferrite films and in multiferroic layered structures. A high accuracy of this method is proven. It was shown that the spin-electromagnetic wave propagating in the structure composed of a thin ferrite film, a thin ferroelectric film, and a slot transmission line is formed as a result of hybridization of the surface spin wave in the ferrite film and the electromagnetic wave in the slot-line. The structure demonstrates dual electric and magnetic field tunability of the SEW spectrum. The electric field tunability is provided by the thin ferroelectric film. Its efficiency increases with an increase in the thicknesses of the ferrite and ferroelectric films and with a decrease in the slot-line gap width. The theory is confirmed by experimental data.

  3. The spectral-angular and polarization characteristics of radiation from an electron beam traversing an inhomogeneous electromagnetic wave

    SciTech Connect

    Koltsov, A.V.; Serov, A.V.

    1995-12-31

    The generation of frequency harmonics of a radiation when the electron beam traverse the inhomogeneous electromagnetic wave was investigated. The electromagnetic wave are linearly polarized. The plane beam of particles enters the wave at right angle with respect to the direction of propogation of the wave and the vector E of the wave. The spartial distribution of radiation from the higher harmonics and the power density contours are caculated.

  4. An energy absorbing far-field boundary condition for the elastic wave equation

    SciTech Connect

    Petersson, N A; Sjogreen, B

    2008-07-15

    The authors present an energy absorbing non-reflecting boundary condition of Clayton-Engquist type for the elastic wave equation together with a discretization which is stable for any ratio of compressional to shear wave speed. They prove stability for a second order accurate finite-difference discretization of the elastic wave equation in three space dimensions together with a discretization of the proposed non-reflecting boundary condition. The stability proof is based on a discrete energy estimate and is valid for heterogeneous materials. The proof includes all six boundaries of the computational domain where special discretizations are needed at the edges and corners. The stability proof holds also when a free surface boundary condition is imposed on some sides of the computational domain.

  5. Simulation and measurement of optimized microwave reflectivity for carbon nanotube absorber by controlling electromagnetic factors.

    PubMed

    Zhang, Danfeng; Hao, Zhifeng; Qian, Yannan; Huang, Yinxin; Bizeng; Yang, Zhenda; Qibai, Wu

    2017-03-28

    Heat-treatments may change the defect and surface organic groups of carbon nanotubes (CNTs), and lead to significant changes in the microwave electromagnetic parameter of CNTs. In this paper, the effect of heat-treatment time and temperature on the complex dielectric constant and permeability as well as the microwave reflectivity of CNTs was investigated. The experimental results indicated that the microwave absorption property of CNTs arises mainly from the high permittivity and consequent dielectric loss. Moreover, the heat-treatment resulted in increased dielectric constant of CNTs and significant improvement of the microwave absorption at frequency values of 2-18 GHz. The microwave reflectivity of CNT composites with a coating thickness of 3 mm was simulated by using the electromagnetic parameters. The absorption peak of CNTs treated at 700 °C had an amplitude of R = -48 dB, which occurred at 9 GHz. Below -10 dB, the composites treated at 900 °C had a bandwidth of 7 GHz. The position of the absorption peak concurred with the measured results. The results indicated that the microwave-absorption properties can be modified by adjusting heat-treatment temperature and time.

  6. Electromagnetic backscattering from one-dimensional drifting fractal sea surface I: Wave-current coupled model

    NASA Astrophysics Data System (ADS)

    Tao, Xie; Shang-Zhuo, Zhao; William, Perrie; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-06-01

    To study the electromagnetic backscattering from a one-dimensional drifting fractal sea surface, a fractal sea surface wave-current model is derived, based on the mechanism of wave-current interactions. The numerical results show the effect of the ocean current on the wave. Wave amplitude decreases, wavelength and kurtosis of wave height increase, spectrum intensity decreases and shifts towards lower frequencies when the current occurs parallel to the direction of the ocean wave. By comparison, wave amplitude increases, wavelength and kurtosis of wave height decrease, spectrum intensity increases and shifts towards higher frequencies if the current is in the opposite direction to the direction of ocean wave. The wave-current interaction effect of the ocean current is much stronger than that of the nonlinear wave-wave interaction. The kurtosis of the nonlinear fractal ocean surface is larger than that of linear fractal ocean surface. The effect of the current on skewness of the probability distribution function is negligible. Therefore, the ocean wave spectrum is notably changed by the surface current and the change should be detectable in the electromagnetic backscattering signal. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Development Program of Jiangsu Higher Education Institutions (PAPD), Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service.

  7. Van Allen Probes observations of cross-scale coupling between electromagnetic ion cyclotron waves and higher-frequency wave modes

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Engebretson, M.; Broughton, M.; Tian, S.; Wygant, J.; Breneman, A.; Thaller, S.

    2016-11-01

    We present observations of higher-frequency ( 50-2500 Hz, 0.1-0.7 fce) wave modes modulated at the frequency of colocated lower frequency (0.5-2 Hz, on the order of fci) waves. These observations come from the Van Allen Probes Electric Field and Waves instrument's burst mode data and represent the first observations of coupling between waves in these frequency ranges. The higher-frequency wave modes, typically whistler mode hiss and chorus or magnetosonic waves, last for a few to a few tens of seconds but are in some cases observed repeatedly over several hours. The higher-frequency waves are observed to be unmodulated before and after the presence of the electromagnetic ion cyclotron (EMIC) waves, but when the EMIC waves are present, the amplitude of the higher-frequency waves drops to the instrument noise level once every EMIC wave cycle. Such modulation could significantly impact wave-particle interactions such as acceleration and pitch angle scattering, which are crucial in the formation and depletion of the radiation belts. We present one case study with broadband, high-frequency waves observed to be modulated by EMIC waves repeatedly over a 2 h time span on both spacecraft. Finally, we show two additional case studies where other high-frequency wave modes exhibit similar modulation.

  8. High order local absorbing boundary conditions for acoustic waves in terms of farfield expansions

    NASA Astrophysics Data System (ADS)

    Villamizar, Vianey; Acosta, Sebastian; Dastrup, Blake

    2017-03-01

    We devise a new high order local absorbing boundary condition (ABC) for radiating problems and scattering of time-harmonic acoustic waves from obstacles of arbitrary shape. By introducing an artificial boundary S enclosing the scatterer, the original unbounded domain Ω is decomposed into a bounded computational domain Ω- and an exterior unbounded domain Ω+. Then, we define interface conditions at the artificial boundary S, from truncated versions of the well-known Wilcox and Karp farfield expansion representations of the exact solution in the exterior region Ω+. As a result, we obtain a new local absorbing boundary condition (ABC) for a bounded problem on Ω-, which effectively accounts for the outgoing behavior of the scattered field. Contrary to the low order absorbing conditions previously defined, the error at the artificial boundary induced by this novel ABC can be easily reduced to reach any accuracy within the limits of the computational resources. We accomplish this by simply adding as many terms as needed to the truncated farfield expansions of Wilcox or Karp. The convergence of these expansions guarantees that the order of approximation of the new ABC can be increased arbitrarily without having to enlarge the radius of the artificial boundary. We include numerical results in two and three dimensions which demonstrate the improved accuracy and simplicity of this new formulation when compared to other absorbing boundary conditions.

  9. Numerical study of electromagnetic waves generated by a prototype dielectric logging tool

    USGS Publications Warehouse

    Ellefsen, K.J.; Abraham, J.D.; Wright, D.L.; Mazzella, A.T.

    2004-01-01

    To understand the electromagnetic waves generated by a prototype dielectric logging tool, a numerical study was conducted using both the finite-difference, time-domain method and a frequency-wavenumber method. When the propagation velocity in the borehole was greater than that in the formation (e.g., an air-filled borehole in the unsaturated zone), only a guided wave propagated along the borehole. As the frequency decreased, both the phase and the group velocities of the guided wave asymptotically approached the phase velocity of a plane wave in the formation. The guided wave radiated electromagnetic energy into the formation, causing its amplitude to decrease. When the propagation velocity in the borehole was less than that in the formation (e.g., a water-filled borehole in the saturated zone), both a refracted wave and a guided wave propagated along the borehole. The velocity of the refracted wave equaled the phase velocity of a plane wave in the formation, and the refracted wave preceded the guided wave. As the frequency decreased, both the phase and the group velocities of the guided wave asymptotically approached the phase velocity of a plane wave in the formation. The guided wave did not radiate electromagnetic energy into the formation. To analyze traces recorded by the prototype tool during laboratory tests, they were compared to traces calculated with the finite-difference method. The first parts of both the recorded and the calculated traces were similar, indicating that guided and refracted waves indeed propagated along the prototype tool. ?? 2004 Society of Exploration Geophysicists. All rights reserved.

  10. Modulation of a compressional electromagnetic wave in a magnetized electron-positron quantum plasma

    NASA Astrophysics Data System (ADS)

    Amin, M. R.

    2015-09-01

    Amplitude modulation of a compressional electromagnetic wave in a strongly magnetized electron-positron pair plasma is considered in the quantum magnetohydrodynamic regime. The important ingredients of this study are the inclusion of the external strong magnetic field, Fermi quantum degeneracy pressure, particle exchange potential, quantum diffraction effects via the Bohm potential, and dissipative effect due to collision of the charged carriers. A modified-nonlinear Schödinger equation is developed for the compressional magnetic field of the electromagnetic wave by employing the standard reductive perturbation technique. The linear and nonlinear dispersions of the electromagnetic wave are discussed in detail. For some parameter ranges, relevant to dense astrophysical objects such as the outer layers of white dwarfs, neutron stars, and magnetars, etc., it is found that the compressional electromagnetic wave is modulationally unstable and propagates as a dissipated electromagnetic wave. It is also found that the quantum effects due to the particle exchange potential and the Bohm potential are negligibly small in comparison to the effects of the Fermi quantum degeneracy pressure. The numerical results on the growth rate of the modulation instability is also presented.

  11. Characterization of porous glass-ceramic material as absorber of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Kazmina, O.; Suslyaev, V.; Dushkina, M.; Semukhin, B.

    2015-04-01

    Investigations of a foam glass-ceramic material synthesized from raw siliceous earth material by the two-stage method at temperatures below 950°C have demonstrated the improvement of its physic mechanical properties in comparison with foam glass synthesized from glass cullet. This material actively interacts with microwaves and can be used for the development of protective screens reducing the adverse effect of microwaves on biological objects, anechoic chambers, and rooms with low level of electromagnetic background noise. Spectra of the transmission and absorption coefficients and of the complex dielectric permittivity for frequencies in the range 26-260 GHz are presented. The observed effects demonstrate the existence of regions with partial and total reflection arising on the glass-pore boundary and of the microwave interaction with ultradisperse carbon particles that remain after foaming with incomplete frothier transition from the soot to the gas phase.

  12. Modelling a point absorbing wave energy converter by the equivalent electric circuit theory: A feasibility study

    NASA Astrophysics Data System (ADS)

    Hai, Ling; Svensson, Olle; Isberg, Jan; Leijon, Mats

    2015-04-01

    There is a need to have a reliable tool to quickly assess wave energy converters (WECs). This paper explores whether it is possible to apply the equivalent electric circuit theory as an evaluation tool for point absorbing WEC system modelling. The circuits were developed starting from the force analysis, in which the hydrodynamic, mechanical, and electrical parameters were expressed by electrical components. A methodology on how to determine the parameters for electrical components has been explained. It is found that by using a multimeter, forces in the connection line and the absorbed electric power can be simulated and read directly from the electric circuit model. Finally, the circuit model has been validated against the full scale offshore experiment. The results indicated that the captured power could be predicted rather accurately and the line force could be estimated accurately near the designed working condition of the WEC.

  13. Development and Testing of a Refractory Millimeter-Wave Absorbent Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Lambot, Thomas; Myrabo, Leik; Murakami, David; Parkin, Kevin

    2014-01-01

    Central to the Millimeter-Wave Thermal Launch System (MTLS) is the millimeter-wave absorbent heat exchanger. We have developed metallic and ceramic variants, with the key challenge being the millimeter-wave absorbent coatings for each. The ceramic heat exchanger came to fruition first, demonstrating for the first time 1800 K peak surface temperatures under illumination by a 110 GHz Gaussian beam. Absorption efficiencies of up to 80 are calculated for mullite heat exchanger tubes and up to 50 are calculated for alumina tubes. These are compared with estimates based on stratified layer and finite element analyses. The problem of how to connect the 1800 K end of the ceramic tubes to a graphite outlet manifold and nozzle is solved by press fitting, or by threading the ends of the ceramic tubes and screwing them into place. The problem of how to connect the ceramic tubes to a metallic or nylon inlet pipe is solved by using soft compliant PTFE and PVC tubes that accommodate thermal deformations of the ceramic tubes during startup and operation. We show the resulting heat exchangers in static tests using argon and helium as propellants.

  14. Total absorption of an electromagnetic wave in an inhomogeneous magnetized plasma

    NASA Astrophysics Data System (ADS)

    Aliev, Iu. M.; Vukovich, S.; Gradov, O. M.; Kirii, A. Iu.; Frolov, A. A.

    1980-05-01

    The paper presents a theoretical analysis of the total absorption of electromagnetic waves by an inhomogeneous magnetoplasma; the analysis has reference to the development of an efficient method of fusion plasma heating by electromagnetic radiation. It is shown that the total absorption is determined by the resonant excitation of damped bulk oscillations of the plasma column. As an example, consideration is given to total resonant absorption during HF plasma heating in a magnetic containment device.

  15. Coupling of electromagnetic waves and space charge waves in type O traveling wave tubes

    NASA Technical Reports Server (NTRS)

    Ricci, P.

    1978-01-01

    H. Derfler observed that a parameter defined by Pierce's perturbation method does not have the same physical significance as an analogous parameter described by a differently derived equation of W. Kleen. A modification of Pierce's method is proposed, which yields an equation of Derfler's type, and also allows quicker and easier calculation of a given traveling wave tube's parameters.

  16. Full-wave model and numerical study of electromagnetic plane wave scattering by multilayered, fiber-based periodic composites

    NASA Astrophysics Data System (ADS)

    Li, C. Y.; Lesselier, D.; Zhong, Y.

    2015-07-01

    The present work aims at building up a full-wave computational model of electromagnetic nondestructive testing of composite materials produced by stacking up dielectric slabs one over the other. In each such dielectric slab, a periodic array of infinite cylindrical fibers is embedded. Electromagnetic scattering of such a multilayered, fiber-based periodic composite is investigated here for an obliquely incident plane wave, the plane of incidence of which differs from the plane orthogonal to the fibers' axes. Full-wave field representations are given first by multipole and plane wave expansions. Mode matching at boundaries between layers then yields the propagating matrices, which are applied to connect reflection and transmission coefficients of the longitudinal field components. Power reflection and transmission coefficients are obtained from time-averaged Poynting vectors. Numerical experiments with comparisons with known results illustrate the accuracy of the model proposed.

  17. Heating of ions by high frequency electromagnetic waves in magnetized plasmas

    SciTech Connect

    Zestanakis, P. A.; Kominis, Y.; Hizanidis, K.; Ram, A. K.

    2013-07-15

    The heating of ions by high frequency electrostatic waves in magnetically confined plasmas has been a paradigm for studying nonlinear wave-particle interactions. The frequency of the waves is assumed to be much higher than the ion cyclotron frequency and the waves are taken to propagate across the magnetic field. In fusion type plasmas, electrostatic waves, like the lower hybrid wave, cannot access the core of the plasma. That is a domain for high harmonic fast waves or electron cyclotron waves—these are primarily electromagnetic waves. Previous studies on heating of ions by two or more electrostatic waves are extended to two electromagnetic waves that propagate directly across the confining magnetic field. While the ratio of the frequency of each wave to the ion cyclotron frequency is large, the frequency difference is assumed to be near the ion cyclotron frequency. The nonlinear wave-particle interaction is studied analytically using a two time-scale canonical perturbation theory. The theory elucidates the effects of various parameters on the gain in energy by the ions—parameters such as the amplitudes and polarizations of the waves, the ratio of the wave frequencies to the cyclotron frequency, the difference in the frequency of the two waves, and the wave numbers associated with the waves. For example, the ratio of the phase velocity of the envelope formed by the two waves to the phase velocity of the carrier wave is important for energization of ions. For a positive ratio, the energy range is much larger than for a negative ratio. So waves like the lower hybrid waves will impart very little energy to ions. The theoretical results are found to be in good agreement with numerical simulations of the exact dynamical equations. The analytical results are used to construct mapping equations, simplifying the derivation of the motion of ions, which are, subsequently, used to follow the evolution of an ion distribution function. The heating of ions can then be

  18. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.

    PubMed

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-03

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 10^{4}  s. This uncertainty can be suppressed by a factor of ∼10^{10}, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ-ray bursts and fast radio bursts.

  19. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals

    NASA Astrophysics Data System (ADS)

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-01

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 1 04 s . This uncertainty can be suppressed by a factor of ˜1 010, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ -ray bursts and fast radio bursts.

  20. A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

    NASA Technical Reports Server (NTRS)

    Simoes, Fernando; Pfaff, Robert; Berthelier, Jean-Jacques; Klenzing, Jeffrey

    2012-01-01

    Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

  1. Experimental demonstration of trapping waves with terahertz metamaterial absorbers on flexible polyimide films

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Liu, Jinsong; Wang, Kejia

    2016-02-01

    We present the design, numerical simulations and experimental measurements of an asymmetric cross terahertz metamaterial absorber (MPA) on ultra-flexible polyimide film. The perfect metamaterial absorber composed of two structured metallic layers separated with a polyimide film with a total thickness of functional layers much smaller than the operational wavelength. Two distinct absorption peaks are found at resonance frequencies of 0.439THz and 0.759 THz with resonance amplitude of near unity, which are in good agreement with the simulation results. The sample is also measured by a THz-TDS imaging system to illustrate the absorption characterization. The scanning images show that the sample could act as a perfect absorber at specific resonance frequencies while a perfect reflector at off resonance frequencies. To illustrate the physical mechanism behind these spectral responses, the distribution of the power loss and surface current are also presented. The result shows that the incident wave is trapped and absorbed by the polyimide dielectric layer at different vicinities of the proposed asymmetric cross MPA for the two absorption peaks. Furthermore, the index sensing performance of the structure is also investigated, and the calculated sensitivity is 90GHz/RIU for f1 mode and 154.7GHz/RIU for f2 mode, indicating that the higher frequency resonance absorption peak has better potential applications in sensing and detection. The ultra-flexible, low cost, high intensity dual band terahertz absorbers may pave the way for designing various terahertz functional devices, such as ultrasensitive terahertz sensors, spatial light modulators and filters.

  2. The electromagnetic signature of gravitational wave interaction with the quantum vacuum

    NASA Astrophysics Data System (ADS)

    Marongwe, Stuart

    An analysis of the effects of the passage of a gravitational wave (GW) on the quantum vacuum is made within the context of the Nexus paradigm of quantum gravity. Results indicate that if the quantum vacuum includes electrically charged virtual particle fields, then a GW will induce vacuum polarization. The equations of General Relativity (GR) are then reformulated to include electric charge displacements in the quantum vacuum imposed by an anisotropic stress — momentum tensor. It is then demonstrated that as a result of the spacetime piezoelectric effect, a gravitational wave is associated with a rotating electromagnetic wave and that the converse effect produced by strong electromagnetic fields is responsible for the generation of relativistic jets and gamma ray bursts. Objects with strong electromagnetic fields will apparently violate the strong equivalence principle.

  3. Generation of electromagnetic waves in the very low frequency band by velocity gradient

    SciTech Connect

    Ganguli, G. Tejero, E.; Crabtree, C.; Amatucci, W.; Rudakov, L.

    2014-01-15

    It is shown that a magnetized plasma layer with a velocity gradient in the flow perpendicular to the ambient magnetic field is unstable to waves in the Very Low Frequency band that spans the ion and electron gyrofrequencies. The waves are formally electromagnetic. However, depending on wave vector k{sup ¯}=kc/ω{sub pe} (normalized by the electron skin depth) and the obliqueness, k{sub ⊥}/k{sub ||}, where k{sub ⊥,||} are wave vectors perpendicular and parallel to the magnetic field, the waves are closer to electrostatic in nature when k{sup ¯}≫1 and k{sub ⊥}≫k{sub ||} and electromagnetic otherwise. Inhomogeneous transverse flows are generated in plasma that contains a static electric field perpendicular to the magnetic field, a configuration that may naturally arise in the boundary layer between plasmas of different characteristics.

  4. Electromagnetic modified Bessel-Gauss beams and waves.

    PubMed

    Seshadri, S R

    2008-01-01

    The transverse magnetic (TM) modified Bessel-Gauss beams and their full-wave generalizations are treated. Attention is paid to the spreading properties on propagation of the null in the radiation intensity pattern for the azimuthal mode numbers m=0 and 1. The rate of spreading of the null in the propagation direction is significantly less for the TM modified Bessel-Gauss waves than those for the corresponding TM Bessel-Gauss waves. The total power transported by the waves is determined and compared with that of the corresponding paraxial beam to estimate the quality of the paraxial beam approximation of the wave. The dependence of the quality of the paraxial beam approximation on the azimuthal mode number, the beam shape parameter, and the ratio of the beam waist to the wavelength has a regular pattern for the TM Bessel-Gauss wave and not for the TM modified Bessel-Gauss wave.

  5. Electromagnetic and Microwave-Absorbing Properties of Plate-Like Nd-Ce-Fe Powder

    NASA Astrophysics Data System (ADS)

    Qiao, Ziqiang; Pan, Shunkang; Xiong, Jilei; Cheng, Lichun; Lin, Peihao; Luo, Jialiang

    2017-01-01

    Plate-like Ce x Nd2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) powders have been synthesized by an arc melting and high-energy ball milling method. The structure of the Nd-Ce-Fe powders was investigated by x-ray diffraction analysis. Their morphology and particle size distribution were evaluated by scanning electron microscopy and laser particle analysis. The saturation magnetization and electromagnetic parameters of the powders were characterized using vibrating-sample magnetometry and vector network analysis, respectively. The results reveal that the Ce x Nd2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) powders consisted of Nd2Fe17 single phase with different Ce contents. The particle size and saturation magnetization decreased with increasing Ce content. The resonant frequencies of ɛ″ and μ″ moved towards lower frequency with increasing Ce concentration. The minimum reflection loss value decreased as the Ce content was increased. The minimum reflection loss and absorption peak frequency of Ce0.2Nd1.8Fe17 with coating thickness of 1.8 mm were -22.5 dB and 7 GHz, respectively. Increasing the values of the complex permittivity and permeability could result in materials with good microwave absorption properties.

  6. Adiabatic description of capture into resonance and surfatron acceleration of charged particles by electromagnetic waves

    SciTech Connect

    Artemyev, A. V.; Zelenyi, L. M.; Vainchtein, D. L.

    2010-12-15

    We present an analytical and numerical study of the surfatron acceleration of nonrelativistic charged particles by electromagnetic waves. The acceleration is caused by capture of particles into resonance with one of the waves. We investigate capture for systems with one or two waves and provide conditions under which the obtained results can be applied to systems with more than two waves. In the case of a single wave, the once captured particles never leave the resonance and their velocity grows linearly with time. However, if there are two waves in the system, the upper bound of the energy gain may exist and we find the analytical value of that bound. We discuss several generalizations including the relativistic limit, different wave amplitudes, and a wide range of the waves' wavenumbers. The obtained results are used for qualitative description of some phenomena observed in the Earth's magnetosphere.

  7. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

    NASA Astrophysics Data System (ADS)

    Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.

    2015-12-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10-6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment.

  8. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

    PubMed Central

    Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.

    2015-01-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10−6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment. PMID:26647962

  9. Self-focusing of intense high frequency electromagnetic waves in a collisional magnetoactive plasma

    SciTech Connect

    Niknam, A. R.; Hashemzadeh, M.; Aliakbari, A.; Majedi, S.; Haji Mirzaei, F.

    2011-11-15

    The self-focusing of an intense electromagnetic beam in a collisional magnetoactive plasma has been investigated by the perturbation method. Considering the relativistic and ponderomotive nonlinearities and the first three terms of perturbation expansion for the electron density and velocity, the nonlinear wave equation is obtained. This wave equation is solved by applying the source dependent expansion method and the evolution of electromagnetic beam spot-size is discussed. It is shown that the laser spot-size decreases with increasing the collision frequency and external magnetic field strength.

  10. Drag current in a quantum superlattice during propagation of a high-intensity bichromatic electromagnetic wave

    NASA Astrophysics Data System (ADS)

    Nosaeva, T. A.; Syrodoev, G. A.

    2016-12-01

    We study the effect of electron drag in a semiconductor superlattice during intraband absorption of a biharmonic electromagnetic wave in a process accompanied by the emission (absorption) of a phonon. The problem has been solved in the second order of perturbation theory. The effective interaction Hamiltonian method makes it possible to take into account the multiphoton nature of the electromagnetic wave absorption. With increasing field, the current increases and attains a peak value, after which it decreases in an oscillatory manner due to the ionization stabilization effect.

  11. Experimental Investigation of the Power Generation Performance of Floating-Point Absorber Wave Energy Systems: Preprint

    SciTech Connect

    Li, Y.; Yu, Y.; Epler, J.; Previsic, M.

    2012-04-01

    The extraction of energy from ocean waves has gained interest in recent years. The floating-point absorber (FPA) is one of the most promising devices among a wide variety of wave energy conversion technologies. Early theoretical studies mainly focused on understanding the hydrodynamics of the system and on predicting the maximum power that could be extracted by a heaving body. These studies evolve from the investigation of floating-body interactions in offshore engineering and naval architecture disciplines. To our best knowledge, no systematic study has been reported about the investigation of the power generation performance of an FPA with a close-to-commercial design. A series of experimental tests was conducted to investigate the power extraction performance of an FPA system.

  12. Electromagnetic waves near the proton cyclotron frequency in the solar wind

    NASA Astrophysics Data System (ADS)

    Jian, Lan; Alexander, Robert; Wicks, Robert; Stevens, Michael; Figueroa-Vinas, Adolfo; Russell, Christopher

    2015-04-01

    Strong narrow-band electromagnetic waves around the proton cyclotron frequency have been found sporadically in the solar wind throughout the inner heliosphere. They are nearly-circularly polarized and propagate close to the magnetic field. Electromagnetic waves near the proton cyclotron frequency can be ion cyclotron waves or magnetosonic waves. They can play an important role in modulating the solar wind ion distribution, and contribute to the heating and acceleration of solar wind. Since the waves are left-hand or right-hand polarized in the spacecraft frame with similar characteristics, they are probably due to Doppler shift of a same type of waves, or there could be a mixture of waves with intrinsically different polarizations. Through the assistance of audification, we have studied the long-lasting low frequency wave events in 2005 using high-cadence magnetic field data from the Wind mission. The Solar Wind Experiment team of the Wind mission has provided the temperature anisotropies for core protons, beam protons, and alpha particles, as well as the beam drift for selected cases. We conduct wave dispersion analysis using these ion moments to examine if these waves can be explained by ion cyclotron anisotropy instability or ion beam instability related to the solar wind inhomogeneities.

  13. Radar Absorbing Materials for Cube Stealth Satellite

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Pastore, R.; Vricella, A.; Marchetti, M.

    A Cube Stealth Satellite is proposed for potential applications in defense system. Particularly, the faces of the satellite exposed to the Earth are made of nanostructured materials able to absorb radar surveillance electromagnetic waves, conferring stealth capability to the cube satellite. Microwave absorbing and shielding material tiles are proposed using composite materials consisting in epoxy-resin and carbon nanotubes filler. The electric permittivity of the composite nanostructured materials is measured and discussed. Such data are used by the modeling algorithm to design the microwave absorbing and the shielding faces of the cube satellite. The electromagnetic modeling takes into account for several incidence angles (0-80°), extended frequency band (2-18 GHz), and for the minimization of the electromagnetic reflection coefficient. The evolutionary algorithm used for microwave layered microwave absorber modeling is the recently developed Winning Particle Optimization. The mathematical model of the absorbing structure is finally experimentally validated by comparing the electromagnetic simulation to the measurement of the manufactured radar absorber tile. Nanostructured composite materials manufacturing process and electromagnetic reflection measurements methods are described. Finally, a finite element method analysis of the electromagnetic scattering by cube stealth satellite is performed.

  14. Electromagnetic absorbing property of the flaky carbonyl iron particles by chemical corrosion process

    NASA Astrophysics Data System (ADS)

    Zheng, Dianliang; Liu, Ting; Zhou, Li; Xu, Yonggang

    2016-12-01

    The flaky carbonyl iron particles (CIPs) were prepared using a milling process at the first step, then the chemical corrosion process was done to optimize the particle shape. The particle morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2-18 GHz and the reflection loss (RL) was calculated. The results showed that the saturation magnetization value of the CIPs decreased as the CIPs was corroded to the small flakes in chemical corrosion process. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was more obvious and the intensity of the diffraction pattern was lower by corrosion. The permittivity and the permeability of the corroded milling CIPs was a little larger than the milling CIPs, it was due to the larger aspect ratio based on the fitting calculation process. At thickness 0.6 mm and 0.8 mm, the corroded milling CIPs composite had the better absorbing property than the other two samples. The frequency band (RL<-5 dB) could be widened to 8.96-18 GHz at 0.6 mm and 5.92-18 GHz at 0.8 mm, and RL less than -8 dB began to exist in 8.96-14.72 GHz at 0.8 mm.

  15. Self-organization of planetary electromagnetic waves in the E-region of the ionosphere

    NASA Astrophysics Data System (ADS)

    Aburjania, G. D.; Jandieri, G. V.; Khantadze, A. G.

    2003-04-01

    A physical mechanism for the generation of slow and fast electromagnetic-type planetary waves due to standing factor-latitude variation of geomagnetic field-in the dissipative E-region of the ionosphere is suggested. It has been shown that slow waves are generated due to the dynamo-field in the ionosphere, and fast waves by the vortical electric field. The slow electromagnetic wave is analog to the Rossby planetary wave; the fast electromagnetic wave is a new mode of natural oscillations of the E-region of the ionosphere. Linear waves propagate along the parallel west and east directions in the dynamo-region of the ionosphere against a background of the mean zonal flow. Phase velocity of the fast waves is a few kms-1, oscillation frequencies are in the frequency band of 10-2-10-4s-1 and the wavelength is of the order of 103km and higher. Phase velocities of the slow waves and local winds are at the same order of magnitude, the frequency band is 10-4-10-5s-1 and wavelength is of 103km and higher order. Fast waves generate intense magnetic fields in order of a few hundred nanotesla (nT); slow waves-a few tens of nT. In this paper the nonlinear theory of both fast and slow planetary electromagnetic waves in the E-region of the ionosphere is investigated for the first time. It was established that these perturbations are self-localized as nonlinear solitary vortical structures in the dynamo-region of the ionosphere move to the west (fast) and to the east (slow) against a background of the mean zonal flow. The nonlinear structure consists of cyclone-anticyclone-type mutual counter-clockwise-rotating vortices, which capture medium particles. Energy and enstrophy of these large-scale vortices are weakly attenuated and are long-lived. Vortical structures generate magnetic fields, which are an order of magnitude larger than those generated by the corresponding linear waves. Features and parameters of electromagnetic wavy structures are theoretically investigated and are in

  16. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves: Waves in Multi-Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves (Khazanov et al., 2003) is presented In order to adequately take into account wave propagation and refraction in a multi-ion magnetosphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate the spatial, temporal, and spectral evolution of the ring current and of electromagnetic ion cyclotron waves To demonstrate the effects of EMIC wave propagation and refraction on the wave energy distribution and evolution, we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, owing to the density gradient at the plasmapause, the net wave refraction is suppressed, and He+-mode grows preferably at the plasmapause. This result is in total agreement with previous ray tracing studies and is very clearly found in presented B field spectrograms. Second, comparison of global wave distributions with the results from another ring current model (Kozyra et al., 1997) reveals that this new model provides more intense and more highly plasmapause-organized wave distributions during the May 1998 storm period Finally, it is found that He(+)-mode energy distributions are not Gaussian distributions and most important that wave energy can occupy not only the region of generation, i.e., the region of small wave normal angles, but all wave normal angles, including those to near 90 . The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping and subsequent downward heat transport and excitation of stable auroral red arcs.

  17. Propagation of electromagnetic waves parallel to the magnetic field in the nightside Venus ionosphere

    NASA Astrophysics Data System (ADS)

    Huba, J. D.; Rowland, H. L.

    1993-03-01

    The propagation of electromagnetic waves parallel to the magnetic field in the nightside Venus ionosphere is presented in a theoretical and numerical analysis. The model assumes a source of electromagnetic radiation in the Venus atmosphere, such as that produced by lightning. Specifically addressed is wave propagation in the altitude range z = 130-160 km at the four frequencies detectable by the Pioneer Venus Orbiter Electric Field Detector: 100 Hz, 730 Hz, 5.4 kHz, and 30 kHz. Parameterizations of the wave intensities, peak electron density, and Poynting flux as a function of magnetic field are presented. The waves are found to propagate most easily in conditions of low electron density and high magnetic field. The results of the model are consistent with observational data.

  18. A novel protocol to measure the attenuation of electromagnetic waves through smoke

    NASA Astrophysics Data System (ADS)

    Yan-wu, Li; Hong-yong, Yuan; Yang, Lu; Xiaoxiang, Zhang; Ru-feng, Xu; Ming, Fu

    2016-06-01

    The electromagnetic properties of smoke from a structure fire are important in terms of their relation to the stability of wireless communication systems used in fire rescue. As it is hard to make a measurable electromagnetic environment for particles in the air, compressed and bulk samples are used instead to measure sand storms and smoke plumes. In this paper, an experiment system was designed to measure smoke particles in the air, in consideration of both smoke control and electromagnetic measurement. Several measures had been taken to create a fulfilled smoke environment. The simulated and measured transmission parameters of the electromagnetic testing area were approximate and the electromagnetic wave frequencies were set from 350 to 400 MHz. Repeated experiments have been conducted to test the stability of the results and they showed that there was no obvious attenuation until the smoke concentration was more than 10 dB m-1. It was found that the frequency around 355 and 360 MHz had a larger attenuation coefficient. The relationship between the attenuation coefficient and the smoke concentration was concluded to be linear. The results may help us understand the attenuation of electromagnetic waves within a smoke column.

  19. Experimental Wave Tank Test for Reference Model 3 Floating-Point Absorber Wave Energy Converter Project

    SciTech Connect

    Yu, Y. H.; Lawson, M.; Li, Y.; Previsic, M.; Epler, J.; Lou, J.

    2015-01-01

    The U.S. Department of Energy established a reference model project to benchmark a set of marine and hydrokinetic technologies including current (tidal, open-ocean, and river) turbines and wave energy converters. The objectives of the project were to first evaluate the status of these technologies and their readiness for commercial applications. Second, to evaluate the potential cost of energy and identify cost-reduction pathways and areas where additional research could be best applied to accelerate technology development to market readiness.

  20. The excitation and detection of lamb waves with planar coil electromagnetic acoustic transducers.

    PubMed

    Wilcox, Paul D; Lowe, Michael J S; Cawley, Peter

    2005-12-01

    Planar coil electromagnetic acoustic transducers (EMATs) are investigated for the excitation and detection of Lamb waves in nonferromagnetic metallic wave-guides. Such EMATs are attractive for certain applications due to their omni-directional sensitivity to wave modes with predominantly in-plane surface displacement, such as the So Lamb wave mode. A model is developed that enables the modal content of the radiated Lamb wave field from a transmitting EMAT to be calculated, and the output voltage from a receiving EMAT to be predicted when a Lamb wave mode is incident on it. The predictions from this model are compared with experimental data obtained from 12 different EMATs tested on a 5-mm thick aluminum plate, and good agreement is obtained. The model then is used to analyze the different effects that contribute to the overall Lamb wave modal sensitivity of an EMAT. The relationship between coil geometry and wavelength is examined.

  1. Geometric Phase Of The Faraday Rotation Of Electromagnetic Waves In Magnetized Plasma

    SciTech Connect

    Jian Liu and Hong Qin

    2011-11-07

    The geometric phase of circularly polarized electromagnetic waves in nonuniform magnetized plasmas is studied theoretically. The variation of the propagation direction of circularly polarized waves results in a geometric phase, which also contributes to the Faraday rotation, in addition to the standard dynamical phase. The origin and properties of the geometric phase is investigated. The in uence of the geometric phase to plasma diagnostics using Faraday rotation is also discussed as an application of the theory.

  2. Electron acceleration by an electromagnetic wave propagating across a magnetic field in periodic structures

    NASA Astrophysics Data System (ADS)

    Buts, V. A.; Ognivenko, V. V.

    1990-05-01

    The possibility of the acceleration of charged particles captured by an electromagnetic wave propagating across a constant magnetic field in periodic slow-wave structures is demonstrated. A plane waveguide with perfectly conducting walls is examined as an example of an electrodynamic structure in which such an acceleration mechanism is possible. The acceleration rate is determined, and the stability of captured particle motion is investigated.

  3. Microwave Absorbing Properties of Metallic Glass/Polymer Composites

    DTIC Science & Technology

    2011-09-01

    Technical Report ARWSB-TR-11022 Microwave Absorbing Properties of Metallic Glass/Polymer Composites Stephen Bartolucci...Technical 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Microwave Absorbing Properties of Metallic Glass/Polymer Composites 5a. CONTRACT...this study, the microwave absorption characteristics of metallic glass / polymer composites were investigated. Electromagnetic wave absorption

  4. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 1; Waves in Multi Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gumayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2003] is presented. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate spatial, temporal, and spectral evolutions of the ring current and electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the EMIC wave energy distributions and evolution we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, due to the density gradient at the plasmapause, the net wave refraction is suppressed, and He(+)-mode grows preferably at plasmapause. This result is in a total agreement with the previous ray tracing studies, and very clear observed in presented B-field spectrograms. Second, comparison the global wave distributions with the results from other ring current model [Kozyra et al., 1997] reveals that our model provides more intense and higher plasmapause organized distributions during the May, 1998 storm period. Finally, the found He(+)-mode energy distributions are not Gaussian distributions, and most important that wave energy can occupy not only the region of generation, i. e. the region of small wave normal angles, but the entire wave normal angle region and even only the region near 90 degrees. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping, and subsequent downward heat transport and excitation of stable auroral red arcs.

  5. Facile Synthesis of Novel Heterostructure Based on SnO2 Nanorods Grown on Submicron Ni Walnut with Tunable Electromagnetic Wave Absorption Capabilities.

    PubMed

    Zhao, Biao; Fan, Bingbing; Shao, Gang; Zhao, Wanyu; Zhang, Rui

    2015-08-26

    In this work, the magnetic-dielectric core-shell heterostructure composites with the core of Ni submicron spheres and the shell of SnO2 nanorods were prepared by a facile two-step route. The crystal structure and morphology were investigated by X-ray diffraction analysis, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). FESEM and TEM measurements present that SnO2 nanorods were perpendicularly grown on the surfaces of Ni spheres and the density of the SnO2 nanorods could be tuned by simply varying the addition amount of Sn(2+) in this process. The morphology of Ni/SnO2 composites were also determined by the concentration of hydrochloric acid and a plausible formation mechanism of SnO2 nanorods-coated Ni spheres was proposed based on hydrochloric acid concentration dependent experiments. Ni/SnO2 composites exhibit better thermal stability than pristine Ni spheres based on thermalgravimetric analysis (TGA). The measurement on the electromagnetic (EM) parameters indicates that SnO2 nanorods can improve the impedance matching condition, which is beneficial for the improvement of electromagnetic wave absorption. When the coverage density of SnO2 nanorod is in an optimum state (diameter of 10 nm and length of about 40-50 nm), the optimal reflection loss (RL) of electromagnetic wave is -45.0 dB at 13.9 GHz and the effective bandwidth (RL below -10 dB) could reach to 3.8 GHz (12.3-16.1 GHz) with the absorber thickness of only 1.8 mm. By changing the loading density of SnO2 nanorods, the best microwave absorption state could be tuned at 1-18 GHz band. These results pave an efficient way for designing new types of high-performance electromagnetic wave absorbing materials.

  6. Broadband field enhancement of THz electromagnetic wave by surface-textured micron PVDF cylinders

    NASA Astrophysics Data System (ADS)

    Li, Xinxin; Liu, Xuan; Zhang, Luoning; Zhou, Jing; Liu, Dahe

    2015-07-01

    A cylindrical dimmer system is proposed to realize broadband field enhancement for terahertz (THz) electromagnetic wave. A surface-textured crescent-shaped cylinder is proposed to red-shift the absorption spectrum comparing to the traditional crescent-shaped cylinder based on the concept of spoof surface plasmons. Such cylinders made of ferroelectric polyvinylidene fluoride can realize the electromagnetic wave harvesting at terahertz frequencies with a broadband and huge absorption cross section. Two such cylinders in close proximity could achieve considerable electromagnetic field enhancement and field confinement in the gap, which could be applied in THz molecules detection, toxic chemical sensing, and safety screening and could break the detection binding that limits the molecules <100 nm.

  7. Dynamic control of electromagnetic wave propagation with the equivalent principle inspired tunable metasurface

    PubMed Central

    Zhu, Bo O.; Chen, Ke; Jia, Nan; Sun, Liang; Zhao, Junming; Jiang, Tian; Feng, Yijun

    2014-01-01

    Transmission and reflection are two fundamental properties of the electromagnetic wave propagation through obstacles. Full control of both the magnitude and phase of the transmission and reflection independently are important issue for free manipulation of electromagnetic wave propagation. Here we employed the equivalent principle, one fundamental theorem of electromagnetics, to analyze the required surface electric and magnetic impedances of a passive metasurface to produce either arbitrary transmission magnitude and phase or arbitrary reflection magnitude and phase. Based on the analysis, a tunable metasurface is proposed. It is shown that the transmission phase can be tuned by 360° with the unity transmissivity or the transmissivity can be tuned from 0 to 1 while the transmission phase is kept around 0°. The reflection magnitude and phase can also been tuned similarly with the proposed metasurface. The proposed design may have many potential applications, such as the dynamic EM beam forming and scanning.

  8. Spin-down of Pulsars, and Their Electromagnetic and Gravitational Wave Radiations

    NASA Astrophysics Data System (ADS)

    Yue-zhu, Zhang; Yan-yan, Fu; Yi-huan, Wei; Cheng-min, Zhang; Shao-hua, Yu; Yuan-yue, Pan; Yuan-qi, Guo; De-hua, Wang

    2016-04-01

    Pulsars posses extremely strong magnetic fields, and their magnetic axis does not coincide with their rotation axis, this causes the pulsars to emit electromagnetic radiations. Pulsars rely on their rotational energy to compensate for the energy loss caused by the electromagnetic radiation, which leads to the gradually decelerated spin of pulsars. According to the theoretical deduction, we have calculated the initial period of the Crab Nebula pulsar, and derived the period evolution of the pulsar at any time in the future under the effect of the electromagnetic radiation. Considered the possible existence of quadrupole moment in the mass distribution of a pulsar, the gravitational wave radiation will also make the pulsar spin down, hence the variation of spin period of the Crab pulsar under the effect of gravitational wave radiation is further analyzed. Finally, combining the two kinds of radiation mechanisms, the evolution of spin period of the Crab pulsar under the joint action of these two kinds of radiation mechanisms is analyzed.

  9. Transversality of Electromagnetic Waves in the Calculus-Based Introductory Physics Course

    ERIC Educational Resources Information Center

    Burko, Lior M.

    2008-01-01

    Introductory calculus-based physics textbooks state that electromagnetic waves are transverse and list many of their properties, but most such textbooks do not bring forth arguments why this is so. Both physical and theoretical arguments are at a level appropriate for students of courses based on such books, and could be readily used by…

  10. Effects of millimeter-wave electromagnetic exposure on the morphology and function of human cryopreserved spermatozoa.

    PubMed

    Volkova, N A; Pavlovich, E V; Gapon, A A; Nikolov, O T

    2014-09-01

    Exposure of human cryopreserved spermatozoa to millimeter-wave electromagnetic radiation of 0.03 mW/cm2 density for 5 min in normozoospermia and for 15 min in asthenozoospermia lead to increase of the fraction of mobile spermatozoa without impairing the membrane integrity and nuclear chromatin status and without apoptosis generation.

  11. NUMERICAL STUDY OF ELECTROMAGNETIC WAVES GENERATED BY A PROTOTYPE DIELECTRIC LOGGING TOOL

    EPA Science Inventory

    To understand the electromagnetic waves generated by a prototype dielectric logging tool, a
    numerical study was conducted using both the finite-difference, time-domain method and a frequency- wavenumber method. When the propagation velocity in the borehole was greater than th...

  12. All-thin-film multilayered multiferroic structures with a slot-line for spin-electromagnetic wave devices

    SciTech Connect

    Nikitin, Andrey A.; Ustinov, Alexey B.; Semenov, Alexander A.; Kalinikos, Boris A.; Lähderanta, E.

    2014-03-03

    Spin-electromagnetic waves propagating in thin-film multilayered multiferroic structures containing a slot transmission line have been investigated both experimentally and theoretically. The thin-film structure was composed of a ferrite film, a ferroelectric film, and a slot-line. It was shown that the spectrum of the spin-electromagnetic wave was formed as a result of hybridization of the spin wave in the ferrite film with the electromagnetic wave in the slot-line and was electrically and magnetically tunable. For the experimental investigations, a microwave phase shifter based on the multiferroic structure has been fabricated. Performance characteristics are presented.

  13. Terahertz electromagnetic wave generation and amplification by an electron beam in the elliptical plasma waveguides with dielectric rod

    SciTech Connect

    Rahmani, Z. Jazi, B.; Heidari-Semiromi, E.

    2014-09-15

    The propagation of electromagnetic waves in an elliptical plasma waveguide including strongly magnetized plasma column and a dielectric rod is investigated. The dispersion relation of guided hybrid electromagnetic waves is obtained. Excitation of the waves by a thin annular relativistic elliptical electron beam will be studied. The time growth rate of electromagnetic waves is obtained. The effects of relative permittivity constant of dielectric rod, radius of dielectric rod, accelerating voltage, and current density of the annular elliptical beam on the growth rate and the frequency spectra are numerically presented.

  14. Excitation and Propagation of Electromagnetic Waves: RBSP Observation and Modeling

    NASA Astrophysics Data System (ADS)

    Zhou, Q.; Xiao, F.; Yang, C.; Liu, S.; Spence, H. E.; Geoffrey, R.; Funsten, H. O.; Blake, J. B.; Baker, D. N.; Wygant, J. R.

    2015-12-01

    During the recovery phase of the geomagnetic storm on 30-31 March 2013, Van Allen Probe A detected enhanced magnetosonic (MS) waves in a broad range of L = 1.8-4.7 and magnetic local time (MLT) = 17-22 h, with a frequency range ˜10-100 Hz. In the meanwhile, distinct proton ring distributions with peaks at energies of ˜10 keV, were also observed in L = 3.2-4.6 and L = 5.0-5.6. Using a subtracted bi-Maxwellian distribution to model the observed proton ring distribution, we perform three-dimensional ray tracing to investigate the instability, propagation, and spatial distribution of MS waves. Numerical results show that nightside MS waves are produced by proton ring distribution and grow rapidly from the source location L = 5.6 to the location L = 5.0 but remain nearly stable at locations L < 5.0. Moreover, waves launched toward lower L shells with different initial azimuthal angles propagate across different MLT regions with divergent paths at first, then gradually turn back toward higher L shells and propagate across different MLT regions with convergent paths. The current results further reveal that MS waves are generated by a ring distribution of ˜10 keV proton and proton ring in one region can contribute to the MS wave power in another region.

  15. Modeling Laser-Tissue Interactions: Implementing the Heat Diffusion Equation and Wave Equation to Simulate Thermal Interactions of Absorber Distributions in Biological Tissues

    NASA Astrophysics Data System (ADS)

    Barrera, Frederick; Ahmed, Elharith; Nash, Patrick; Sardar, Dhiraj

    2011-03-01

    The tracking of photons through turbid media (e.g. tissues) has been studied extensively from an experimental vantage point. These turbid media are difficult to characterize- since their components are exceedingly variegated- and thus present many challenges to clinicians who require models which precisely predict the location and time evolution of energy deposition. Furthermore, the interaction of the turbid media sample with the source of radiation typically involves many dynamic mechanisms (e.g. photothermal etc.) Using diffuse light transport, and an electromagnetic wave approach (e.g. Maxwell's equations), an analysis of thermal energy distribution in tissues is performed. Assuming a highly absorbing chromophore model of melanocytes in tissues, a comparison of the variation of thermal energy is determined for different collections of melanocyte spatial distributions. This work was funded by NIH/NIGMS MBRS-RISE GM60655.

  16. Modeling the propagation of electromagnetic waves over the surface of the human body

    NASA Astrophysics Data System (ADS)

    Vendik, I. B.; Vendik, O. G.; Kirillov, V. V.; Pleskachev, V. V.; Tural'chuk, P. A.

    2016-12-01

    The results of modeling and an experimental study of electromagnetic (EM) waves in microwave range propagating along the surface of the human body have been presented. The parameters of wave propagation, such as the attenuation and phase velocity, have also been investigated. The calculation of the propagation of EM waves by the numerical method FDTD (finite difference time domain), as well as the use of the analytical model of the propagation of the EM wave along flat and curved surfaces has been fulfilled. An experimental study on a human body has been conducted. It has been shown that creeping waves are slow and exhibit a noticeable dispersion, while the surface waves are dispersionless and propagate at the speed of light in free space. A comparison of the results of numerical simulation, analytical calculation, and experimental investigations at a frequency of 2.55 GHz has been carried out.

  17. Numerical evaluation of external magnetic effect on electromagnetic wave transmission through reentry plasma layer

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Bo, Yong; Lei, Mingda; Liu, Shuzhang; Liu, Ying; Liu, Jianwei; Zhao, Yizhe

    2016-11-01

    Numerical study of electromagnetic (EM) wave transmission through the magnetized plasma layer is presented in this paper. The plasma parameters are derived from computational fluid dynamics simulation of the flow field around a blunt body flying at supersonic speed and serve as the background plasma condition in the numerical modeling for EM wave transmission. The EM wave is generated by our newly designed coaxial feed GPS patch antenna. The external magnetic field is applied and assumed to vary linearly as a function of wall distance. The effects of the external applied magnetic field and the plasma parameters on wave transmission are studied, and the results show that EM wave propagation in the non-uniformly magnetized plasma is a matter of impedance matching, and the EM wave transmission can be adjusted only when the proper strength of the magnetic field is applied.

  18. Electromagnetic wave absorption properties of Fe73Si16B7Nb3Cu1-based composites mixed with fine charcoal powder

    NASA Astrophysics Data System (ADS)

    Kim, Sun-I.; Kim, Mi Rae; Sohn, Keun Yong; Park, Won-Wook

    2010-05-01

    Fe73Si16B7Nb3Cu1 soft magnetic powder was crystallized to obtain a nano grain structure and mixed with a fine charcoal powder. The mixtures were tape-cast with polymer-based organic binders to form a sheet-type electromagnetic (EM) wave absorption composite. The EM wave absorption properties of the sheets were investigated using a network analyzer. The results showed that addition of charcoal powder improved the EM-absorbing properties of the composite. The power loss of the EM wave was directly related to the imaginary part of the permeability and permittivity, and it was reviewed in detail. Excellent absorption properties were achieved by adding 5 wt % charcoal powder (-500 mesh) to the Fe-based sheets.

  19. Electromagnetic wave emitting products and "Kikoh" potentiate human leukocyte functions.

    PubMed

    Niwa, Y; Iizawa, O; Ishimoto, K; Jiang, X; Kanoh, T

    1993-09-01

    Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called "Kikoh" in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4-14 microns). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of "Kikohshi" i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury.

  20. Coupled equations of electromagnetic waves in nonlinear metamaterial waveguides.

    PubMed

    Azari, Mina; Hatami, Mohsen; Meygoli, Vahid; Yousefi, Elham

    2016-11-01

    Over the past decades, scientists have presented ways to manipulate the macroscopic properties of a material at levels unachieved before, and called them metamaterials. This research can be considered an important step forward in electromagnetics and optics. In this study, higher-order nonlinear coupled equations in a special kind of metamaterial waveguides (a planar waveguide with metamaterial core) will be derived from both electric and magnetic components of the transverse electric mode of electromagnetic pulse propagation. On the other hand, achieving the refractive index in this research is worthwhile. It is also shown that the coupled equations are not symmetric with respect to the electric and magnetic fields, unlike these kinds of equations in fiber optics and dielectric waveguides. Simulations on the propagation of a fundamental soliton pulse in a nonlinear metamaterial waveguide near the resonance frequency (a little lower than the magnetic resonant frequency) are performed to study its behavior. These pulses are recommended to practice in optical communications in controlled switching by external voltage, even in low power.

  1. Electromagnetic wave emitting products and ``Kikoh'' potentiate human leukocyte functions

    NASA Astrophysics Data System (ADS)

    Niwa, Yukie; Iizawa, Osamu; Ishimoto, Koichi; Jiang, Xiaoxia; Kanoh, Tadashi

    1993-09-01

    Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called “Kikoh” in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4 14 µm). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of “Kikohshi” i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury.

  2. Frequency Management for Electromagnetic Continuous Wave Conductivity Meters

    PubMed Central

    Mazurek, Przemyslaw; Putynkowski, Grzegorz

    2016-01-01

    Ground conductivity meters use electromagnetic fields for the mapping of geological variations, like the determination of water amount, depending on ground layers, which is important for the state analysis of embankments. The VLF band is contaminated by numerous natural and artificial electromagnetic interference signals. Prior to the determination of ground conductivity, the meter’s working frequency is not possible, due to the variable frequency of the interferences. Frequency management based on the analysis of the selected band using track-before-detect (TBD) algorithms, which allows dynamical frequency changes of the conductivity of the meter transmitting part, is proposed in the paper. Naive maximum value search, spatio-temporal TBD (ST-TBD), Viterbi TBD and a new algorithm that uses combined ST-TBD and Viterbi TBD are compared. Monte Carlo tests are provided for the numerical analysis of the properties for a single interference signal in the considered band, and a new approach based on combined ST-TBD and Viterbi algorithms shows the best performance. The considered algorithms process spectrogram data for the selected band, so DFT (Discrete Fourier Transform) could be applied for the computation of the spectrogram. Real–time properties, related to the latency, are discussed also, and it is shown that TBD algorithms are feasible for real applications. PMID:27070608

  3. Frequency Management for Electromagnetic Continuous Wave Conductivity Meters.

    PubMed

    Mazurek, Przemyslaw; Putynkowski, Grzegorz

    2016-04-07

    Ground conductivity meters use electromagnetic fields for the mapping of geological variations, like the determination of water amount, depending on ground layers, which is important for the state analysis of embankments. The VLF band is contaminated by numerous natural and artificial electromagnetic interference signals. Prior to the determination of ground conductivity, the meter's working frequency is not possible, due to the variable frequency of the interferences. Frequency management based on the analysis of the selected band using track-before-detect (TBD) algorithms, which allows dynamical frequency changes of the conductivity of the meter transmitting part, is proposed in the paper. Naive maximum value search, spatio-temporal TBD (ST-TBD), Viterbi TBD and a new algorithm that uses combined ST-TBD and Viterbi TBD are compared. Monte Carlo tests are provided for the numerical analysis of the properties for a single interference signal in the considered band, and a new approach based on combined ST-TBD and Viterbi algorithms shows the best performance. The considered algorithms process spectrogram data for the selected band, so DFT (Discrete Fourier Transform) could be applied for the computation of the spectrogram. Real-time properties, related to the latency, are discussed also, and it is shown that TBD algorithms are feasible for real applications.

  4. Nonlinear propagation of coherent electromagnetic waves in a dense magnetized plasma

    SciTech Connect

    Shukla, P. K.; Eliasson, B.; Stenflo, L.

    2012-07-15

    We present an investigation of the nonlinear propagation of high-frequency coherent electromagnetic waves in a uniform quantum magnetoplasma. Specifically, we consider nonlinear couplings of right-hand circularly polarized electromagnetic-electron-cyclotron (CPEM-EC) waves with dispersive shear Alfven (DSA) and dispersive compressional Alfven (DCA) perturbations in plasmas composed of degenerate electron fluids and non-degenerate ion fluids. Such interactions lead to amplitude modulation of the CPEM-EC wave packets, the dynamics of which is governed by a three-dimensional nonlinear Schroedinger equation (NLSE) with the frequency shift arising from the relativistic electron mass increase in the CPEM-EC fields and density perturbations associated with the DSA and DCA perturbations. Accounting for the electromagnetic and quantum forces, we derive the evolution equation for the DSA and DCA waves in the presence of the magnetic field-aligned ponderomotive force of the CPEM-EC waves. The NLSE and the driven DSA and DCA equations are then used to investigate the modulational instability. The relevance of our investigation to laser-plasma interaction experiments and the cores of white dwarf stars is pointed out.

  5. The electromagnetic-trait imaging computation of traveling wave method in breast tumor microwave sensor system.

    PubMed

    Tao, Zhi-Fu; Han, Zhong-Ling; Yao, Meng

    2011-01-01

    Using the difference of dielectric constant between malignant tumor tissue and normal breast tissue, breast tumor microwave sensor system (BRATUMASS) determines the detected target of imaging electromagnetic trait by analyzing the properties of target tissue back wave obtained after near-field microwave radicalization (conelrad). The key of obtained target properties relationship and reconstructed detected space is to analyze the characteristics of the whole process from microwave transmission to back wave reception. Using traveling wave method, we derive spatial transmission properties and the relationship of the relation detected points distances, and valuate the properties of each unit by statistical valuation theory. This chapter gives the experimental data analysis results.

  6. Scattering of electromagnetic waves from a magnetized plasma column at oblique incidence

    SciTech Connect

    Ghaffari-Oskooei, Sara S.; Aghamir, Farzin M.

    2015-07-14

    Scattering of electromagnetic waves from a magnetized plasma column is investigated using Maxwell's equations and applying boundary conditions. Backscattering cross section is evaluated by analytic solution of electric fields inside and outside of plasma column. Plots of backscattering cross section versus frequency, for the range up to J band, reveal two main peaks and two sidebands. Effects of plasma density and radius, as main parameters determining the characteristics of plasma column, on backscattering are discussed. Furthermore, the effect of electromagnetic wave incidence angle on backscattering of plasma column is included in the analysis. The influence of wave incidence angle and frequency, as well as, plasma density and radius on scattering pattern, which is an indicator of the distribution of scattered power in different azimuthal angles, is discussed.

  7. Method for locating underground anomalies by diffraction of electromagnetic waves passing between spaced boreholes

    DOEpatents

    Lytle, R. Jeffrey; Lager, Darrel L.; Laine, Edwin F.; Davis, Donald T.

    1979-01-01

    Underground anomalies or discontinuities, such as holes, tunnels, and caverns, are located by lowering an electromagnetic signal transmitting antenna down one borehole and a receiving antenna down another, the ground to be surveyed for anomalies being situated between the boreholes. Electronic transmitting and receiving equipment associated with the antennas is activated and the antennas are lowered in unison at the same rate down their respective boreholes a plurality of times, each time with the receiving antenna at a different level with respect to the transmitting antenna. The transmitted electromagnetic waves diffract at each edge of an anomaly. This causes minimal signal reception at the receiving antenna. Triangulation of the straight lines between the antennas for the depths at which the signal minimums are detected precisely locates the anomaly. Alternatively, phase shifts of the transmitted waves may be detected to locate an anomaly, the phase shift being distinctive for the waves directed at the anomaly.

  8. Distributed source model for the full-wave electromagnetic simulation of nonlinear terahertz generation.

    PubMed

    Fumeaux, Christophe; Lin, Hungyen; Serita, Kazunori; Withayachumnankul, Withawat; Kaufmann, Thomas; Tonouchi, Masayoshi; Abbott, Derek

    2012-07-30

    The process of terahertz generation through optical rectification in a nonlinear crystal is modeled using discretized equivalent current sources. The equivalent terahertz sources are distributed in the active volume and computed based on a separately modeled near-infrared pump beam. This approach can be used to define an appropriate excitation for full-wave electromagnetic numerical simulations of the generated terahertz radiation. This enables predictive modeling of the near-field interactions of the terahertz beam with micro-structured samples, e.g. in a near-field time-resolved microscopy system. The distributed source model is described in detail, and an implementation in a particular full-wave simulation tool is presented. The numerical results are then validated through a series of measurements on square apertures. The general principle can be applied to other nonlinear processes with possible implementation in any full-wave numerical electromagnetic solver.

  9. Geometric phase coded metasurface: from polarization dependent directive electromagnetic wave scattering to diffusion-like scattering

    PubMed Central

    Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian

    2016-01-01

    Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence. PMID:27775064

  10. Geometric phase coded metasurface: from polarization dependent directive electromagnetic wave scattering to diffusion-like scattering

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian

    2016-10-01

    Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence.

  11. Electromagnetic wave propagation in rain and polarization effects

    PubMed Central

    OKAMURA, Sogo; OGUCHI, Tomohiro

    2010-01-01

    This paper summarizes our study on microwave and millimeter-wave propagation in rain with special emphasis on the effects of polarization. Starting from a recount of our past findings, we will discuss developments with these and how they are connected with subsequent research. PMID:20551593

  12. Finite element modeling of electromagnetic fields and waves using NASTRAN

    NASA Technical Reports Server (NTRS)

    Moyer, E. Thomas, Jr.; Schroeder, Erwin

    1989-01-01

    The various formulations of Maxwell's equations are reviewed with emphasis on those formulations which most readily form analogies with Navier's equations. Analogies involving scalar and vector potentials and electric and magnetic field components are presented. Formulations allowing for media with dielectric and conducting properties are emphasized. It is demonstrated that many problems in electromagnetism can be solved using the NASTRAN finite element code. Several fundamental problems involving time harmonic solutions of Maxwell's equations with known analytic solutions are solved using NASTRAN to demonstrate convergence and mesh requirements. Mesh requirements are studied as a function of frequency, conductivity, and dielectric properties. Applications in both low frequency and high frequency are highlighted. The low frequency problems demonstrate the ability to solve problems involving media inhomogeneity and unbounded domains. The high frequency applications demonstrate the ability to handle problems with large boundary to wavelength ratios.

  13. Theory of a ring laser. [electromagnetic field and wave equations

    NASA Technical Reports Server (NTRS)

    Menegozzi, L. N.; Lamb, W. E., Jr.

    1973-01-01

    Development of a systematic formulation of the theory of a ring laser which is based on first principles and uses a well-known model for laser operation. A simple physical derivation of the electromagnetic field equations for a noninertial reference frame in uniform rotation is presented, and an attempt is made to clarify the nature of the Fox-Li modes for an open polygonal resonator. The polarization of the active medium is obtained by using a Fourier-series method which permits the formulation of a strong-signal theory, and solutions are given in terms of continued fractions. It is shown that when such a continued fraction is expanded to third order in the fields, the familiar small-signal ring-laser theory is obtained.

  14. Electromagnetic waves and living cells: A kinetic thermodynamic approach

    NASA Astrophysics Data System (ADS)

    Lucia, Umberto

    2016-11-01

    Cells are complex thermodynamic systems. Their energy transfer, thermo-electro-chemical processes and transports phenomena can occur across the cells membranes, the border of the complex system. Moreover, cells can also actively modify their behaviours in relation to any change of their environment. All the living systems waste heat, which is no more than the result of their internal irreversibility. This heat is dissipated into their environment. But, this wasted heat represents also a sort of information, which outflows from the cell towards its environment, completely accessible to any observer. The analysis of irreversibility related to this wasted heat can represent a new useful approach to the study of the cells behaviour. This approach allows us to consider the living systems as black boxes and analyse only the inflows and outflows and their changes in relation to any environmental change. This analysis allows also the explanation of the effects of electromagnetic fields on the cell behaviour.

  15. Some consequences of intense electromagnetic wave injection into space plasmas

    NASA Astrophysics Data System (ADS)

    Burke, William J.; Villalon, Elena; Rothwell, Paul L.; Silevitch, Michael

    1986-10-01

    The future possibility of actively testing the current understanding of how energetic particles may be accelerated in space or dumped from the radiation belts using intense electromagnetic energy from ground based antennas is discussed. The ground source of radiation is merely a convenience. A space station source for radiation that does not have to pass through the atmosphere and lower ionosphere, is an attractive alternative. The text is divided into two main sections addressing the possibilities of: (1) accelerating electrons to fill selected flux tubes above the Kennel-Petscheck limit for stably trapped fluxes, and (2) using an Alfven maser to cause rapid depletion of energetic protons or electrons from the radiation belts.

  16. Some consequences of intense electromagnetic wave injection into space plasmas

    NASA Technical Reports Server (NTRS)

    Burke, William J.; Rothwell, Paul L.; Rothwell, Paul L.; Rothwell, Paul L.

    1986-01-01

    The future possibility of actively testing the current understanding of how energetic particles may be accelerated in space or dumped from the radiation belts using intense electromagnetic energy from ground based antennas is discussed. The ground source of radiation is merely a convenience. A space station source for radiation that does not have to pass through the atmosphere and lower ionosphere, is an attractive alternative. The text is divided into two main sections addressing the possibilities of: (1) accelerating electrons to fill selected flux tubes above the Kennel-Petscheck limit for stably trapped fluxes, and (2) using an Alfven maser to cause rapid depletion of energetic protons or electrons from the radiation belts.

  17. High Frequency Resonant Electromagnetic Generation and Detection of Ultrasonic Waves

    NASA Astrophysics Data System (ADS)

    Kawashima, Katsuhiro; Wright, Oliver; Hyoguchi, Takao

    1994-05-01

    High frequency resonant mode electromagnetic ultrasonic generation and detection in metals is demonstrated at frequencies up to ˜150 MHz with various metal sheet samples. Using a unified theory of the generation and detection process, it is shown how various physical quantities can be measured. The sound velocity or thickness of the sheets can be derived from the resonant frequencies. At resonance the detected amplitude is inversely proportional to the ultrasonic attenuation of the sample, whereas the resonance half-width is proportional to this attenuation. We derive the ultrasonic attenuation coefficient from the half-width, and show how the grain size of the material can be probed. In addition we present results for thin bonded sheets, and show how a measure of the bonding or delamination can be obtained. This high frequency resonant method shows great promise for the non-destructive evaluation of thin sheets and coatings in the sub- 10-µm to 1-mm thickness range.

  18. Possible electromagnetic interference with electronic medical equipment by radio waves coming from outside the hospital.

    PubMed

    Hanada, E; Kodama, K; Takano, K; Watanabe, Y; Nose, Y

    2001-08-01

    Electromagnetic interference (EMI) with electronic medical equipment by radio waves from mobile telephone handsets has been reported and is currently receiving wide attention. The possibility of EMI with electronic medical equipment by radio waves coming into the hospital has also been pointed out. But so far, there are no reports measuring the frequency distribution of electric field intensity induced by incoming radio waves. Therefore, we measured electric field intensity induced by radio waves coming into our 11-floor hospital, which was under construction. The maximum intensity observed was about 200 V/m at 2.79 GHz, from airport surveillance radar waves. The maximum intensity induced by radio waves from cellular phone base stations was 1.78 V/m. These data show that various frequencies of radio waves are common in this urban area, and that they induce strong electricfield intensity. This strong electric field intensity might cause EMI with electronic medical equipment. Measurement of the electromagnetic environment should be done by each hospital in urban areas to prevent EMI with electronic medical equipment.

  19. Bursty, Broadband Electromagnetic Waves Associated with Thin Current Layers and Turbulent Magnetosheath Reconnection

    NASA Technical Reports Server (NTRS)

    Adrian, M. L.; Wendel, D. E.

    2011-01-01

    We investigate observations of intense bursts of electromagnetic wave energy in association with the thin current layers of turbulent magnetosheath reconnection. These observed emissions form two distinct types: (i) broadband emissions that extend continuously to lOs of Hertz; and (ii) structured bursts of emitted energy that occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed at local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic energy and quantify their proximity to X- and O-nulls, as well as their correlation to the amount of magnetic energy converted by the process of magnetic reconnection.

  20. Scattering forces and electromagnetic momentum density in crossed circularly polarized standing waves.

    PubMed

    Marqués, Manuel I; Saénz, Juan José

    2012-07-01

    We analyze the forces on a small dipolar particle and the electromagnetic momentum density in a configuration consisting in two perpendicular circularly polarized stationary waves. The field distribution shows regions in which the electric and magnetic fields are parallel corresponding to a null Poynting vector. Although the average value of the momentum density, proportional to the Poynting vector, is zero in these regions, there are scattering forces acting on small particles due to light's spin force. The total scattering force suggests a new definition of the average value of the momentum density for free propagating electromagnetic fields.

  1. Scattering forces and electromagnetic momentum density in crossed circularly polarized standing waves.

    PubMed

    Marqués, Manuel I; Saénz, Juan José

    2012-07-15

    We analyze the forces on a small dipolar particle and the electromagnetic momentum density in a configuration consisting in two perpendicular circularly polarized stationary waves. The field distribution shows regions in which the electric and magnetic fields are parallel corresponding to a null Poynting vector. Although the average value of the momentum density, proportional to the Poynting vector, is zero in these regions, there are scattering forces acting on small particles due to light's spin force. The total scattering force suggests a new definition of the average value of the momentum density for free propagating electromagnetic fields.

  2. Interaction of relativistically strong electromagnetic waves with a layer of overdense plasma

    SciTech Connect

    Korzhimanov, A. V.; Eremin, V. I. Kim, A. V.; Tushentsov, M. R.

    2007-10-15

    Plasma-field structures that arise under the interaction between a relativistically strong electromagnetic wave and a layer of overdense plasma are considered within a quasistationary approximation. It is shown that, together with known solutions, which are nonlinear generalizations of skin-layer solutions, multilayer structures containing cavitation regions with completely removed electrons (ion layers) can be excited when the amplitude of the incident field exceeds a certain threshold value. Under symmetric irradiation, these cavitation regions, which play the role of self-consistent resonators, may amplify the field and accumulate electromagnetic energy.

  3. Apparatus and method for enhanced chemical processing in high pressure and atmospheric plasmas produced by high frequency electromagnetic waves

    SciTech Connect

    Efthimion, P.C.; Helfritch, D.J.

    1989-11-28

    This paper describes an apparatus which creates a plasma for chemical processing of gaseous fluid. It comprises an electro-magnetic resonator cavity having first and second conductive walls and a resonant frequency; an electro-magnetic energy source which produces electro-magnetic energy having a frequency corresponding to the resonant frequency and a power level sufficient for breaking down the gaseous fluid and creating a plasma within the electro-magnetic resonator cavity; an electro-magnetic wave guiding structure connecting the electro-magnetic energy source to the first wall of the electro-magnetic cavity; the wave guiding structure having an intake port for introducing the gaseous fluid into the wave guiding structure; the second wall of the resonator cavity having an exhaust port for discharging processed gaseous fluid in the form of a plasma from the cavity; and plasma confinement means for causing the gaseous fluid to flow into the electro-magnetic resonator cavity through the aperture along with the electro-magnetic energy for confining and stabilizing the plasma within the electro-magnetic resonator cavity.

  4. Asymmetric propagation of electromagnetic waves through nanoscale spirals

    NASA Astrophysics Data System (ADS)

    Hu, Jingpei; Lin, Yu; Zhu, Aijiao; Zhao, Xiaonan; Wang, Chinhua

    2016-10-01

    In this paper, we report that normal incidence transmission of different circularly polarized waves through the 2D Archimedes' nanoscale spirals is asymmetric. The structures consist of raised spiral ridge and two layers metal film covered on the substrate and the ridge. The finite difference time domain method was used to design the structure and perform the simulation. The device can distinguish the different circularly polarized wave across the transmission intensity compare with the common Archimedes' nanoscale spirals which just exhibit the bright or dark modes in the light field. We confirmed that the device provide about 10% circular dichroism in 3.85um-6.0um broadband region. The circular dichroism in the wavelength 3.95 um can reach 13%. This ultracompact device could prove useful for remote sensing and advanced telecommunication applications.

  5. Dynamic control of asymmetric electromagnetic wave transmission by active chiral metamaterial

    PubMed Central

    Chen, Ke; Feng, Yijun; Cui, Li; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-01-01

    The asymmetric transmission of electromagnetic (EM) wave can be fully manipulated by chiral metamaterials, but little can achieve real-time and high efficient tunability due to challenges in practically deployable solutions. Here, we proposed a new scheme for flexibly and dynamically controlling the asymmetric EM wave transmission at microwave frequencies using planar metamaterial of deep subwavelength thickness incorporated with active components of PIN diodes. The asymmetric transmission of linearly polarized EM wave exhibits a high efficiency and a pronounced real-time continuous tunability controlled by the external stimulation of voltage biasing. In addition, the asymmetric transmission effect can be well preserved at large oblique incident angle up to ±70°. The design principle and EM performance are validated by both full wave simulations and experimental measurements. Such dynamically controllable chiral metamaterial may provide robust and flexible approach to manipulate EM wave propagation, as well as to facilitate EM device integration to create diverse functionalities. PMID:28202903

  6. Dynamic control of asymmetric electromagnetic wave transmission by active chiral metamaterial.

    PubMed

    Chen, Ke; Feng, Yijun; Cui, Li; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-02-16

    The asymmetric transmission of electromagnetic (EM) wave can be fully manipulated by chiral metamaterials, but little can achieve real-time and high efficient tunability due to challenges in practically deployable solutions. Here, we proposed a new scheme for flexibly and dynamically controlling the asymmetric EM wave transmission at microwave frequencies using planar metamaterial of deep subwavelength thickness incorporated with active components of PIN diodes. The asymmetric transmission of linearly polarized EM wave exhibits a high efficiency and a pronounced real-time continuous tunability controlled by the external stimulation of voltage biasing. In addition, the asymmetric transmission effect can be well preserved at large oblique incident angle up to ±70°. The design principle and EM performance are validated by both full wave simulations and experimental measurements. Such dynamically controllable chiral metamaterial may provide robust and flexible approach to manipulate EM wave propagation, as well as to facilitate EM device integration to create diverse functionalities.

  7. Dynamic control of asymmetric electromagnetic wave transmission by active chiral metamaterial

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Feng, Yijun; Cui, Li; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-02-01

    The asymmetric transmission of electromagnetic (EM) wave can be fully manipulated by chiral metamaterials, but little can achieve real-time and high efficient tunability due to challenges in practically deployable solutions. Here, we proposed a new scheme for flexibly and dynamically controlling the asymmetric EM wave transmission at microwave frequencies using planar metamaterial of deep subwavelength thickness incorporated with active components of PIN diodes. The asymmetric transmission of linearly polarized EM wave exhibits a high efficiency and a pronounced real-time continuous tunability controlled by the external stimulation of voltage biasing. In addition, the asymmetric transmission effect can be well preserved at large oblique incident angle up to ±70°. The design principle and EM performance are validated by both full wave simulations and experimental measurements. Such dynamically controllable chiral metamaterial may provide robust and flexible approach to manipulate EM wave propagation, as well as to facilitate EM device integration to create diverse functionalities.

  8. Nonlinear interactions of electromagnetic waves with the auroral ionosphere

    SciTech Connect

    Wong, Alfred Y.

    1999-09-20

    The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO{sub 2} through the use of ion cyclotron resonant heating.

  9. Nonlinear interactions of electromagnetic waves with the auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Wong, Alfred Y.

    1999-09-01

    The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO2 through the use of ion cyclotron resonant heating.

  10. Perfect terahertz absorber using fishnet based metafilm

    SciTech Connect

    Azad, Abul Kalam; Shchegolkov, Dmitry Yu; Chen, Houtong; Taylor, Antoinette; Smirnova, E I; O' Hara, John F

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  11. Impact of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2007-01-01

    Effect of the ring current ions in the real part of electromagnetic ion Cyclotron wave dispersion relation is studied on global scale. Recent Cluster observations by Engebretson et al. showed that although the temperature anisotropy of is energetic (> 10 keV) ring current protons was high during the entire 22 November 2003 perigee pass, electromagnetic ion cyclotron waves were observed only in conjunction with intensification of the ion fluxes below 1 keV by over an order of magnitude. To study the effect of the ring current ions on the wave dispersive properties and the corresponding global wave redistribution, we use a self-consistent model of interacting ring current and electromagnetic ion cyclotron waves, and simulate the May 1998 storm. The main findings of our simulation can be summarized as follows: First, the plasma density enhancement in the night MLT sector during the main and recovery storm phases is mostly caused by injection of suprathermal plasma sheet H + (approximately < 1 keV), which dominate the thermal plasma density. Second, during the recovery storm phases, the ring current modification of the wave dispersion relation leads to a qualitative change of the wave patterns in the postmidnight-dawn sector for L > 4.75. This "new" wave activity is well organized by outward edges of dense suprathermal ring current spots, and the waves are not observed if the ring current ions are not included in the real part of dispersion relation. Third, the most intense wave-induced ring current precipitation is located in the night MLT sector and caused by modification of the wave dispersion relation. The strongest precipitating fluxes of about 8 X 10(exp 6)/ (cm(exp 2) - s X st) are found near L=5.75, MLT=2 during the early recovery phase on 4 May. Finally, the nightside precipitation is more intense than the dayside fluxes, even if there are less intense waves, because the convection field moves ring current ions into the loss cone on the nightside, but drives

  12. Wideband characterization of the complex wave number and characteristic impedance of sound absorbers.

    PubMed

    Salissou, Yacoubou; Panneton, Raymond

    2010-11-01

    Several methods for measuring the complex wave number and the characteristic impedance of sound absorbers have been proposed in the literature. These methods can be classified into single frequency and wideband methods. In this paper, the main existing methods are revisited and discussed. An alternative method which is not well known or discussed in the literature while exhibiting great potential is also discussed. This method is essentially an improvement of the wideband method described by Iwase et al., rewritten so that the setup is more ISO 10534-2 standard-compliant. Glass wool, melamine foam and acoustical/thermal insulator wool are used to compare the main existing wideband non-iterative methods with this alternative method. It is found that, in the middle and high frequency ranges the alternative method yields results that are comparable in accuracy to the classical two-cavity method and the four-microphone transfer-matrix method. However, in the low frequency range, the alternative method appears to be more accurate than the other methods, especially when measuring the complex wave number.

  13. Dispersion characteristics of the electromagnetic waves in a relativistic electron beam guided by the ion channel

    SciTech Connect

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Ghasemi, Maede; Sedaghat, Zeinab; Mahdian, Zeinab

    2010-05-15

    In this article, the dispersion characteristics of the paraxial (near axis) electromagnetic (EM) waves in a relativistic electron beam guided by the ion channel are investigated. Equilibrium fields such as ion-channel electrostatic field and self-fields of relativistic electron beam are included in this formalism. In accordance with the equilibrium field structure, radial and azimuthal waves are selected as base vectors for EM waves. It is shown that the dispersion of the radially polarized EM and space charge waves are influenced by the equilibrium fields, but azimuthally polarized wave remain unaffected. In some wave number domains, the radially polarized EM and fast space charge waves are coupled. In these regions, instability is analyzed as a function of equilibrium structure. It is shown that the total equilibrium radial force due to the ion channel and electron beam and also relativistic effect play a key role in the coupling of the radially polarized EM wave and space charge wave. Furthermore, some asymptotic behaviors such as weak and strong ion channel, nonrelativistic case and cutoff frequencies are discussed. This instability could be used as an amplification mechanism for radially polarized EM waves in a beam-plasma system where a relativistic electron beam is guided by the ion channel.

  14. Propagation and Generation of Electromagnetic Waves at Proton Gyrofrequencies in a Relativistic Electron-Positron Plasma. II. Excitation of Electromagnetic Waves

    NASA Astrophysics Data System (ADS)

    Zheleznyakov, V. V.; Bespalov, P. A.

    2016-04-01

    In part I of this work [1], we study the dispersion characteristics of low-frequency waves in a relativistic electron-positron plasma. In part II, we examine the electromagnetic wave instability in this plasma caused by an admixture of nonrelativistic protons with energy comparable with the energy of relativistic low-mass particles. The instability occurs in the frequency band between the fundamental harmonic of proton gyrofrequency and the fundamental harmonic of relativistic electron gyrofrequency. The results can be used for the interpretation of known observations of the pulsar emissions obtained with a high time and frequency resolution. The considered instability can probably be the initial stage of the microwave radio emission nanoshots typical of the pulsar in the Crab Nebula.

  15. Study of Rotating-Wave Electromagnetic Modes for Applications in Space Exploration

    NASA Astrophysics Data System (ADS)

    Velazco, J. E.

    2016-08-01

    Rotating waves are circularly polarized electromagnetic wave fields that behave like traveling waves but have discrete resonant frequencies of standing waves. In JPL's Communications Ground Systems Section (333), we are making use of this peculiar type of electromagnetic modes to develop a new generation of devices and instruments for direct applications in space exploration. In this article, we present a straightforward analysis about the phase velocity of these wave modes. A derivation is presented for the azimuthal phase velocity of transverse magnetic rotating modes inside cylindrical cavity resonators. Computer simulations and experimental measurements are also presented that corroborate the theory developed. It is shown that the phase velocity of rotating waves inside cavity resonators increases with radial position within the cavity and decreases when employing higher-order operating modes. The exotic features of rotating modes, once better understood, have the potential to enable the implementation of a plethora of new devices that range from amplifiers and frequency multipliers to electron accelerators and ion thrusters.

  16. Dynamics of the large-scale ULF electromagnetic wave structures in the ionosphere

    NASA Astrophysics Data System (ADS)

    Aburjania, G. D.; Chargazia, Z. Kh.

    2007-12-01

    The present article displays the results of theoretical investigation of the planetary ultra-low-frequency (ULF) electromagnetic wave structure, generation and propagation dynamics in the dissipative ionosphere. These waves are stipulated by a spatial inhomogeneous geomagnetic field. The waves propagate in different ionospheric layers along the parallels to the east as well as to the west and their frequencies vary in the range of (10 10-6) s-1 with a wavelength of order 103 km. The fast disturbances are associated with oscillations of the ionospheric electrons frozen in the geomagnetic field. The large-scale waves are weakly damped. They generate the geomagnetic field adding up to several tens of nanotesla (nT) near the Earth's surface. It is prescribed that the planetary ULF electromagnetic waves preceding their nonlinear interaction with the local shear winds can self-localize in the form of nonlinear long-living solitary vortices, moving along the latitude circles westward as well as eastward with a velocity different from the phase velocity of the corresponding linear waves. The vortex structures transfer the trapped particles of medium, as well as energy and heat. That is why such nonlinear vortex structures can be the structural elements of the ionospheric strong macro-turbulences.

  17. Effects of Millimeter-Wave Electromagnetic Radiation on the Experimental Model of Migraine.

    PubMed

    Sivachenko, I B; Medvedev, D S; Molodtsova, I D; Panteleev, S S; Sokolov, A Yu; Lyubashina, O A

    2016-02-01

    Effects of millimeter-wave electromagnetic radiation (40 GHz frequency, 0.01 mW power) on the spontaneous fi ring of convergent neurons of the spinal trigeminal nucleus and their responses to electrical stimulation of the dura mater were studied in neurophysiological experiments on rats. Irradiation of the area of cutaneous receptive fields of spinal trigeminal nucleus reversibly inhibited both spontaneous discharges and activity induced by electrical stimulation of the dura mater. The second and third exposures to electromagnetic radiation with an interval of 10 min were ineffective. These results suggest that suppression of neuronal excitability in the spinal trigeminal ganglion can be a mechanism of the anti-migraine effects of electromagnetic radiation observed in clinical practice.

  18. Exact solutions for the source-excited cylindrical electromagnetic waves in a nonlinear nondispersive medium.

    PubMed

    Es'kin, V A; Kudrin, A V; Petrov, E Yu

    2011-06-01

    The behavior of electromagnetic fields in nonlinear media has been a topical problem since the discovery of materials with a nonlinearity of electromagnetic properties. The problem of finding exact solutions for the source-excited nonlinear waves in curvilinear coordinates has been regarded as unsolvable for a long time. In this work, we present the first solution of this type for a cylindrically symmetric field excited by a pulsed current filament in a nondispersive medium that is simultaneously inhomogeneous and nonlinear. Assuming that the medium has a power-law permittivity profile in the linear regime and lacks a center of inversion, we derive an exact solution for the electromagnetic field excited by a current filament in such a medium and discuss the properties of this solution.

  19. Amplification of the snow melting effect on the heat wave over the Eurasia by absorbing aerosols

    NASA Astrophysics Data System (ADS)

    Kim, M. K.; Kim, K. M.; Lau, W. K. M.; Sang, J.; Yasunari, T. J.

    2015-12-01

    In this study, we present the potential impact of snow darkening effect on the Eurasian heat wave by absorbing aerosols using the NASA GEOS-5 Model experiments with aerosol tracers and a state-of-the-art snow darkening module for the land surface. Results show that snow darkening effect (SDE) can have a significant influence on not only the intensity but also the duration of heatwave during snow melting season, i.e., late spring season over the mid-western Eurasia and early summer season over the central northern Eurasia. During the early snow melting season surface air temperature is significantly increased by 3-6K due to early snow melting and enhanced solar radiation. Moreover enhanced evaporation induced by surface energy surplus during the early melting season leads to the new equilibrium level with lower soil moisture over the Eurasia since snow melting season, and thereby provide favorable condition for severe droughts and heat wave over the large parts of the Eurasia. This finding suggests that the SDE may play an important role in amplifying the snow melting effect on large-scale heat wave over the Eurasia. Energy and water balance at the surface supporting this findings are also discussed from evaporation-precipitation recycling point of view.

  20. Morphology-Control Synthesis of a Core-Shell Structured NiCu Alloy with Tunable Electromagnetic-Wave Absorption Capabilities.

    PubMed

    Zhao, Biao; Zhao, Wanyu; Shao, Gang; Fan, Bingbing; Zhang, Rui

    2015-06-17

    In this work, dendritelike and rodlike NiCu alloys were prepared by a one-pot hydrothermal process at various reaction temperatures (120, 140, and 160 °C). The structure and morphology were analyzed by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and transmission electron microscopy, which that demonstrate NiCu alloys have core-shell heterostructures with Ni as the shell and Cu as the core. The formation mechanism of the core-shell structures was also discussed. The uniform and perfect dendritelike NiCu alloy obtained at 140 °C shows outstanding electromagnetic-wave absorption properties. The lowest reflection loss (RL) of -31.13 dB was observed at 14.3 GHz, and the effective absorption (below -10 dB, 90% attenuation) bandwidth can be adjusted between 4.4 and 18 GHz with a thin absorber thickness in the range of 1.2-4.0 mm. The outstanding electromagnetic-wave-absorbing properties are ascribed to space-charge polarization arising from the heterogeneous structure of the NiCu alloy, interfacial polarization between the alloy and paraffin, and continuous micronetworks and vibrating microcurrent dissipation originating from the uniform and perfect dendritelike shape of NiCu prepared at 140 °C.

  1. Transient Electromagnetic Wave Propagation in a Plasma Waveguide

    DTIC Science & Technology

    2011-10-24

    across the dielectric -wire surface boundary and utilizes a steady-state sinusoidal approximation . The standard analysis neglects how the wave was... analysis provides a consistent notation for the closed plasma waveguide and suggests possible launching modes with minimal loss. The initial condition...2 III. TRANSIENT ANALYSIS OF A CYLINDRICAL PLASMA WAVEGUIDE ……….….………11 IV. FINITE-ELEMENT COMPUTATIONS…………………………………………………………..21 V

  2. Merger of binary neutron stars: Gravitational waves and electromagnetic counterparts

    NASA Astrophysics Data System (ADS)

    Shibata, Masaru

    2016-12-01

    Late inspiral and merger phases of binary neutron stars are the valuable new experimental fields for exploring nuclear physics because (i) gravitational waves from them will bring information for the neutron-star equation of state and (ii) the matter ejected after the onset of the merger could be the main site for the r-process nucleosynthesis. We will summarize these aspects of the binary neutron stars, describing the current understanding for the merger process of binary neutron stars that has been revealed by numerical-relativity simulations.

  3. Features of the ELF Electromagnetic Wave Propagation in the Homogeneous Ionosphere

    NASA Astrophysics Data System (ADS)

    Sergeev, Igor

    The quasi-stationary Maxwell equations of the gyrotropic waves have been examined. In con-trast to the approach used in the other papers (Sorokin et al., 2009; Sorokin et al., 2006; Sergeev and Sorokin, 2005) the general form of the electromagnetic equation of the gyrotropic waves has been considered. The dispersion equation analysis shows that attenuation of one of the mode tends to zero in the perpendicular to the magnetic field direction while along this direction the attenuation is finite. Basing on this feature we can suppose that low frequency electromagnetic fluctuations tend to expand along the magnetic field. It forms in the iono-sphere long areas with invariable direction of the electric field and current and weakly variable magnitude of these parameters. To check this conclusion the direct problem of the evolution of an electromagnetic fluctuation has been solved numerically. The results show that spherically symmetric fluctuation expands along the magnetic field lines by 5-30 times while in some cases the widening is fully absent. References Sorokin V.M., Sergeev I.Yu., Pokhotelov O.A. Low latitude gyrotropic waves in a finite thickness ionospheric conducting layer. Journal of Atmospheric and Solar-Terrestrial Physics, V. 71, P. 175-179, 2009. Sorokin V.M., Sergeev I.Yu., and Yaschenko A.K. Electromagnetic field generation by explosion in the ionosphere. Advances in Space Research, V. 38, No. 11, P. 2511-2515, 2006. Sergeev I.Yu. and Sorokin V.M. Mechanism of the LF Narrow-Band Spectrum Electromagnetic Disturbance Formation Observed on the Earth Surface during Spacecraft Launches. Geomag-netism and Aeronomy, Vol. 45, No. 4, P. 520-525, 2005.

  4. A photoexcited switchable perfect metamaterial absorber/reflector with polarization-independent and wide-angle for terahertz waves

    NASA Astrophysics Data System (ADS)

    Cheng, Yongzhi; Gong, Rongzhou; Zhao, Jingcheng

    2016-12-01

    We present a photoexcited switchable perfect metamaterial absorber/reflector for terahertz waves. The switchable absorber/reflector is based on a cross-shaped structure (CSS) integrated semiconductor photoconductive silicon (Si). The electric response property of the photoconductive Si can be easily modified through a pump optical beam. The conductivity of Si pads filled in the gap of CSS is tuned efficiently through the incident pump optical beam with different power, resulting in the modulation of absorption magnitude from 0 to 100% at the fixed operation frequency. Thus, the switch ability of the perfect absorber/reflector can be easily realized. Furthermore, the proposed design is polarization insensitive and operated well at wide incidence angles for both TE and TM waves.

  5. 2D modeling of electromagnetic waves in cold plasmas

    SciTech Connect

    Crombé, K.; Van Eester, D.; Koch, R.; Kyrytsya, V.

    2014-02-12

    The consequences of sheath (rectified) electric fields, resulting from the different mobility of electrons and ions as a response to radio frequency (RF) fields, are a concern for RF antenna design as it can cause damage to antenna parts, limiters and other in-vessel components. As a first step to a more complete description, the usual cold plasma dielectric description has been adopted, and the density profile was assumed to be known as input. Ultimately, the relevant equations describing the wave-particle interaction both on the fast and slow timescale will need to be tackled but prior to doing so was felt as a necessity to get a feeling of the wave dynamics involved. Maxwell's equations are solved for a cold plasma in a 2D antenna box with strongly varying density profiles crossing also lower hybrid and ion-ion hybrid resonance layers. Numerical modelling quickly becomes demanding on computer power, since a fine grid spacing is required to capture the small wavelengths effects of strongly evanescent modes.

  6. Stimulated Raman back scattering of extraordinary electromagnetic waves from periodically magnetized nanoparticle lattice

    SciTech Connect

    Chakhmachi, A.

    2013-06-15

    Stimulated Raman back scattering of extraordinary electromagnetic waves from the nanoparticle lattice is investigated in the presence of the static magnetic field. In the context of macroscopic theory, dispersion relation and growth rate of extraordinary mode for different values of static magnetic field and lattice parameters are derived and analyzed. It is found that when the static magnetic field is off, dispersion relation has two branches. These branches are related to the plasmonic and body wave branches of the plane polarized wave. Low frequency branch of the pump wave is not involved in the instability while the other branch is not stable, and the growth rate of Raman back scattered wave has one peak. If the electrons have cyclotron frequency by static magnetic field, dispersion has three branches. These branches are related to the plasmonic and body wave branches of left and right hand circularly polarized waves. In this situation, it is found that low frequency lower branch of the pump wave is stable while other branches are not stable, and the growth rate of Raman back scattered wave has three peaks. Numerical study of growth rate in various cyclotron frequencies shows that the growth rate increases and the instability band width decreases with increasing static magnetic field.

  7. Nonlinear propagation of Rossby-Khantadze electromagnetic planetary waves in the ionospheric E-layer

    SciTech Connect

    Futatani, S.; Horton, W.; Kaladze, T. D.

    2013-10-15

    Nonlinear vortex propagation of electromagnetic coupled Rossby and Khantadze planetary waves in the weakly ionized ionospheric E-layer is investigated with numerical simulations. Large scale, finite amplitude vortex structures are launched as initial conditions at low, mid, and high latitudes. For each k-vector the linear dispersion relation has two eigenmodes corresponding to the slow magnetized Rossby wave and the fast magnetic Khantadze wave. Both waves propagate westward with local speeds of the order of 10–20 m/s for the slow wave and of the order of 500–1000 km/s for the fast wave. We show that for finite amplitudes there are dipole solitary structures emitted from the initial conditions. These structures are neutrally stable, nonlinear states that avoid radiating waves by propagating faster than the corresponding linear wave speeds. The condition for these coherent structures to occur is that their amplitudes are such that the nonlinear convection around the core of the disturbance is faster than the linear wave speed for the corresponding dominant Fourier components of the initial disturbance. The presence of the solitary vortex states is indicative of an initial strong disturbance such as that from a solar storm or a tectonic plate movement. We show that for generic, large amplitude initial disturbances both slow and fast vortex structures propagate out of the initial structure.

  8. Beta Decay in the Field of an Electromagnetic Wave and Experiments on Measuring the Neutrino Mass

    SciTech Connect

    Dorofeev, O.F.; Lobanov, A.E.

    2005-06-01

    Investigations of the effect of an electromagnetic wave field on the beta-decay process are used to analyze the tritium-decay experimental data on the neutrino mass. It is shown that the electromagnetic wave can distort the beta spectrum, shifting the end point to the higher energy region. This phenomenon is purely classical and it is associated with the electron acceleration in the radiation field. Since strong magnetic fields exist in setups for precise measurement of the neutrino mass, the indicated field can appear owing to the synchrotron radiation mechanism. The phenomenon under consideration can explain the experimentally observed anomalies in the spectrum of the decay electrons; in particular, the effect of the 'negative square of the neutrino mass'.

  9. Correlation between intensity fluctuations of electromagnetic waves scattered from a spatially quasi-homogeneous, anisotropic medium.

    PubMed

    Li, Jia; Chen, Feinan; Chang, Liping

    2016-10-17

    Within the validity of the first-order Born approximation, expressions are derived for the correlation between intensity fluctuations (CIF) of an electromagnetic plane wave scattered from a spatially quasi-homogeneous (QH), anisotropic medium. Upon establishing the correlation matrix of the scattering potential of the medium, we show that the CIF is the summation of Fourier transforms of the strengths and normalized correlation coefficients (NCCs) of the scattering potential matrix. Numerical results reveal that the CIF is susceptible to the effective width and correlation length of the medium, and degree of polarization of the incident electromagnetic wave. Our study not only extends the current knowledge of the CIF of a scattered field but also provides an important reference to the study of high-order intensity correlations of light scattered from a spatially anisotropic medium.

  10. Breatherlike electromagnetic wave propagation in an antiferromagnetic medium with Dzyaloshinsky-Moriya interaction

    SciTech Connect

    Kavitha, L.; Saravanan, M.; Srividya, B.; Gopi, D.

    2011-12-15

    We investigate the nature of propagation of electromagnetic waves (EMWs) in an antiferromagnetic medium with Dzyaloshinsky-Moriya (DM) interaction environment. The interplay of bilinear and DM exchange spin coupling with the magnetic field component of the EMW has been studied by solving Maxwell's equations coupled with a nonlinear spin equation for the magnetization of the medium. We made a nonuniform expansion of the magnetization and magnetic field along the direction of propagation of EMW, in the framework of reductive perturbation method, and the dynamics of the system is found to be governed by a generalized derivative nonlinear Schroedinger (DNLS) equation. We employ the Jacobi-elliptic function method to solve the DNLS equation, and the electromagnetic wave propagation in an antiferromagnetic medium is governed by the breatherlike spatially and temporally coherent localized modes under the influence of DM interaction parameter.

  11. Hybrid electrodynamics and kinetics simulation for electromagnetic wave propagation in weakly ionized hydrogen plasmas.

    PubMed

    Chen, Qiang; Chen, Bin

    2012-10-01

    In this paper, a hybrid electrodynamics and kinetics numerical model based on the finite-difference time-domain method and lattice Boltzmann method is presented for electromagnetic wave propagation in weakly ionized hydrogen plasmas. In this framework, the multicomponent Bhatnagar-Gross-Krook collision model considering both elastic and Coulomb collisions and the multicomponent force model based on the Guo model are introduced, which supply a hyperfine description on the interaction between electromagnetic wave and weakly ionized plasma. Cubic spline interpolation and mean filtering technique are separately introduced to solve the multiscalar problem and enhance the physical quantities, which are polluted by numerical noise. Several simulations have been implemented to validate our model. The numerical results are consistent with a simplified analytical model, which demonstrates that this model can obtain satisfying numerical solutions successfully.

  12. Shear driven electromagnetic drift-waves in a nonuniform dense magnetoplasma

    SciTech Connect

    Tariq, Sabeen; Mirza, Arshad M.; Masood, Waqas

    2011-08-15

    Linear characteristic properties of high- and low-frequency (in comparison with the cyclotron frequency) electromagnetic drift-waves are studied in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel (magnetic field-aligned) velocity shear, by using quantum magnetohydrodynamic model. By applying the drift-approximation (viz., |{partial_derivative} {sub t}|<<{omega}{sub ci}<<{omega}{sub ce}) to the quantum momentum equations, together with the continuity equations and the Poisson equation, we derive the governing equations for electromagnetic drift-waves with the shear flow. These linear equations are then Fourier transformed to obtain the dispersion relation in both high-frequency and low-frequency regimes. The dispersion relations are then discussed under various limiting cases.

  13. Electromagnetic wave propagation with negative phase velocity in regular black holes

    SciTech Connect

    Sharif, M. Manzoor, R.

    2012-12-15

    We discuss the propagation of electromagnetic plane waves with negative phase velocity in regular black holes. For this purpose, we consider the Bardeen model as a nonlinear magnetic monopole and the Bardeen model coupled to nonlinear electrodynamics with a cosmological constant. It turns out that the region outside the event horizon of each regular black hole does not support negative phase velocity propagation, while its possibility in the region inside the event horizon is discussed.

  14. Electromagnetic wave propagation through aperiodic superlattices composed of left- and right-handed materials

    NASA Astrophysics Data System (ADS)

    Salejda, Wlodzimierz; Klauzer-Kruszyna, Agnieszka; Tyc, Michal H.; Tarnowski, Karol

    2005-09-01

    Using the transfer matrix formalism and dynamical maps technique, we calculate numerically transmittance of polarized electromagnetic wave through aperiodic superlattices (generalized Fibonacci, generalized Thue-Morse, double-periodic and Rudin-Shapiro), built of left- and right-handed materials. In our calculations, strong dispersion of left-handed materials is taken into account, leading to tunnelling effects in a wide range of wavelengths and incidence angles. The results are presented in gray scale transmittance maps.

  15. Theory of electromagnetic cyclotron wave growth in a time-varying magnetoplasma

    NASA Technical Reports Server (NTRS)

    Gail, William B.

    1990-01-01

    The effect of a time-dependent perturbation in the magnetoplasma on the wave and particle populations is investigated using the Kennel-Petchek (1966) approach. Perturbations in the cold plasma density, energetic particle distribution, and resonance condition are calculated on the basis of the ideal MHD assumption given an arbitrary compressional magnetic field perturbation. An equation is derived describing the time-dependent growth rate for parallel propagating electromagnetic cyclotron waves in a time-varying magnetoplasma with perturbations superimposed on an equilibrium configuration.

  16. Effects of energetic heavy ions on electromagnetic ion cyclotron wave generation in the plasmapause region

    NASA Technical Reports Server (NTRS)

    Kozyra, J. U.; Cravens, T. E.; Nagy, A. F.; Fontheim, E. G.; Ong, R. S. B.

    1984-01-01

    An expression for electromagnetic ion cyclotron convective growth rates is derived. The derivation of the dispersion relation and convective growth rates in the presence of a multicomponent energetic and cold plasma is presented. The effects that multiple heavy ions in the ring current and cold plasma produce in the growth and propagation characteristics of ion cyclotron waves are explored. Results of growth rate calculations using parameters consistent with conditions in the plasmapause region during the early recovery phase of geomagnetic storms are presented and compared with ground-based and satellite observations of waves in this region. The geophysical implications of the results are discussed.

  17. Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

    SciTech Connect

    Norin, L.; Leyser, T. B.; Nordblad, E.; Thide, B.; McCarrick, M.

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

  18. Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

    PubMed

    Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

  19. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    NASA Astrophysics Data System (ADS)

    Abramov, Arnold; Kostikov, Alexander

    2017-03-01

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder.

  20. Negative-Refractive Bicrystal with Broken Symmetry Produces Asymmetric Electromagnetic Fields in Guided-Wave Heterostructures

    NASA Astrophysics Data System (ADS)

    Krowne, Clifford M.

    2004-07-01

    Heterostructure arrangements of uniaxial bicrystals have been discovered to produce electromagnetic fields with asymmetric distributions in guide wave structures. The property behind this remarkable phenomenon is the broken crystalline symmetry which allows the new physics to be seen in unsymmetric distributions. Here the theory behind this phenomenon is presented, numerical calculations are performed using an ab initio anisotropic Green’s function approach, and the results provided at 10 GHz for a realistic crystal system with nominal permittivity of 5. Asymmetric distributions seen here are one facet of the broken symmetry property which generates negative refraction for impinging waves on a bicrystal.

  1. Predicting electromagnetic ion cyclotron wave amplitude from unstable ring current plasma conditions

    NASA Astrophysics Data System (ADS)

    Fu, Xiangrong; Cowee, Misa M.; Jordanova, Vania K.; Gary, S. Peter; Reeves, Geoffrey D.; Winske, Dan

    2016-11-01

    Electromagnetic ion cyclotron (EMIC) waves in the Earth's inner magnetosphere are enhanced fluctuations driven unstable by ring current ion temperature anisotropy. EMIC waves can resonate with relativistic electrons and play an important role in precipitation of MeV radiation belt electrons. In this paper, we investigate the excitation and saturation of EMIC instability in a homogeneous plasma using both linear theory and nonlinear hybrid simulations. We have explored a four-dimensional parameter space, carried out a large number of simulations, and derived a scaling formula that relates the saturation EMIC wave amplitude to initial plasma conditions. Such scaling can be used in conjunction with ring current models like ring current-atmosphere interactions model with self-consistent magnetic field to provide global dynamic EMIC wave maps that will be more accurate inputs for radiation belt modeling than statistical models.

  2. Electromagnetic Ion Cyclotron Waves in the Inner Magnetosphere with a Kappa-Maxwellian Proton Distribution

    NASA Astrophysics Data System (ADS)

    Singh, S.; Sugiyama, H.; Omura, Y.; Shoji, M.; Nunn, D.; Summers, D.

    2014-12-01

    Electromagnetic ion cyclotron (EMIC) waves are studied in kappa-Maxwellian plasma. The plasma is assumed to have five-components, i.e., electrons, cold and hot protons, singly charged helium and oxygen ions. The hot anisotropic protons are assumed to have kappa-Maxwellian anisotropic particle distribution function. The numerical results are obtained using KUPDAP (Kyoto University Plasma Dispersion Analysis Package), a full dispersion solver developed at Kyoto University. The growth/damping of oxygen, helium, and proton bands and higher harmonics of the EMIC waves are studied. The effects of the kappa distribution on the growth/damping of these waves are clearly demonstrated. The findings from our model are applied to EMIC wave observations in the inner magnetosphere by the Cluster spacecraft.

  3. Electromagnetic ion cyclotron waves in the Earth's magnetosphere with a kappa-Maxwellian particle distribution

    NASA Astrophysics Data System (ADS)

    Sugiyama, Hajime; Singh, Satyavir; Omura, Yoshiharu; Shoji, Masafumi; Nunn, David; Summers, Danny

    2015-10-01

    A theoretical model to study electromagnetic ion cyclotron (EMIC) waves in kappa-Maxwellian plasma is developed. The plasma is assumed to have five components, i.e., electrons, cool and hot protons, and singly charged helium and oxygen ions. The kappa-Maxwellian anisotropic particle distribution function is assumed for the hot protons. We use the Kyoto University Plasma Dispersion Analysis Package, a full dispersion solver developed at Kyoto University, to obtain the numerical results and delineate the oxygen, helium, and proton bands. Higher harmonics of the EMIC waves are also studied, and the effects of the kappa distribution on the growth of these waves are clearly demonstrated. Our results are applied to Cluster spacecraft observations of EMIC waves in the inner magnetosphere.

  4. Finite element approach analysis for characteristics of electromagnetic acoustic Lamb wave

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoming; Li, Songsong

    2016-04-01

    The electromagnetic acoustic Lamb wave, with the advantages of quickly detecting the defect and sensitivity to the defects, is widely used in non-destructive testing of thin sheet. In this paper, the directivity of sound field, Phase velocity, group velocity and particle displacement amplitude of Lamb wave are study based on finite element analysis method. The results show that, for 1mm aluminum, when the excitation frequency 0.64MHz, the displacement amplitude of A0 mode is minimum, and the displacement amplitude S0 mode is largest. Appropriate to increase the displacement amplitude of a mode, while reducing displacement amplitude of another mode, to achieve the excitation of a single mode Lamb wave. It is helpful to the Optimization of transducer parameters, the choice of Lamb wave modes and providing optimal excitation frequency.

  5. Nonlinear gyrokinetic equations for low-frequency electromagnetic waves in general plasma equilibria

    SciTech Connect

    Frieman, E.A.; Chen, L.

    1981-10-01

    A nonlinear gyrokinetic formalism for low-frequency (less than the cyclotron frequency) microscopic electromagnetic perturbations in general magnetic field configurations is developed. The nonlinear equations thus derived are valid in the strong-turbulence regime and contain effects due to finite Larmor radius, plasma inhomogeneities, and magentic field geometries. The specific case of axisymmetric tokamaks is then considered, and a model nonlinear equation is derived for electrostatic drift waves. Also, applying the formalism to the shear Alfven wave heating sceme, it is found that nonlinear ion Landau damping of kinetic shear-Alfven waves is modified, both qualitatively and quantitatively, by the diamagnetic drift effects. In particular, wave energy is found to cascade in wavenumber instead of frequency.

  6. Quantifying and predicting meat and meat products quality attributes using electromagnetic waves: an overview.

    PubMed

    Damez, Jean-Louis; Clerjon, Sylvie

    2013-12-01

    The meat industry needs reliable meat quality information throughout the production process in order to guarantee high-quality meat products for consumers. Besides laboratory researches, food scientists often try to adapt their tools to industrial conditions and easy handling devices useable on-line and in slaughterhouses already exist. This paper overviews the recently developed approaches and latest research efforts related to assessing the quality of different meat products by electromagnetic waves and examines the potential for their deployment. The main meat quality traits that can be assessed using electromagnetic waves are sensory characteristics, chemical composition, physicochemical properties, health-protecting properties, nutritional characteristics and safety. A wide range of techniques, from low frequency, high frequency impedance measurement, microwaves, NMR, IR and UV light, to X-ray interaction, involves a wide range of physical interactions between the electromagnetic wave and the sample. Some of these techniques are now in a period of transition between experimental and applied utilization and several sensors and instruments are reviewed.

  7. Fabrication process and electromagnetic wave absorption characterization of a CNT/Ni/epoxy nanocomposite.

    PubMed

    Ryu, Seongwoo; Mo, Chan Bin; Lee, Haeshin; Hong, Soon Hyung

    2013-11-01

    Since carbon nanotube (CNT) was first discovered in 1991, it has been considered as a viable type of conductive filler for electromagnetic wave absorption materials in the GHz range. In this paper, pearl-necklace-structure CNT/Ni nano-powders were fabricated by a polyol process as conductive fillers. Compared to synthesized CNT, pearl-necklace Ni-decorated CNT increased the electrical conductivity by an order of 1 due to the enhancement of the Ni-conductive network. Moreover, the decorated Ni particles prevented the agglomeration of CNTs by counterbalancing the Van der Walls interaction between the CNTs. A CNT/Ni nanocomposite showed a homogeneous dispersion in an epoxy-based matrix. This enhanced physical morphology and electrical properties lead to an increase in the loss tangent and reflection loss in the CNT/Ni/Epoxy nanocomposite compared to these characteristics of a CNT/Epoxy nanocomposite in range of 8-12 GHz. The electromagnetic wave absorption properties of CNT/Ni/epoxy nanocomposites will provide enormous opportunities for electronic applications where lightweight EMI shielding or electro-magnetic wave absorption properties are necessary.

  8. A large volume uniform plasma generator for the experiments of electromagnetic wave propagation in plasma

    SciTech Connect

    Yang Min; Li Xiaoping; Xie Kai; Liu Donglin; Liu Yanming

    2013-01-15

    A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a 'black out' phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm Multiplication-Sign 260 mm Multiplication-Sign 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.

  9. Probing extra dimension through gravitational wave observations of compact binaries and their electromagnetic counterparts

    NASA Astrophysics Data System (ADS)

    Yu, Hao; Gu, Bao-Min; Huang, Fa Peng; Wang, Yong-Qiang; Meng, Xin-He; Liu, Yu-Xiao

    2017-02-01

    The future gravitational wave (GW) observations of compact binaries and their possible electromagnetic counterparts may be used to probe the nature of the extra dimension. It is widely accepted that gravitons and photons are the only two completely confirmed objects that can travel along null geodesics in our four-dimensional space-time. However, if there exist extra dimensions and only GWs can propagate freely in the bulk, the causal propagations of GWs and electromagnetic waves (EMWs) are in general different. In this paper, we study null geodesics of GWs and EMWs in a five-dimensional anti-de Sitter space-time in the presence of the curvature of the universe. We show that for general cases the horizon radius of GW is longer than EMW within equal time. Taking the GW150914 event detected by the Advanced Laser Interferometer Gravitational-Wave Observatory and the X-ray event detected by the Fermi Gamma-ray Burst Monitor as an example, we study how the curvature k and the constant curvature radius l affect the horizon radii of GW and EMW in the de Sitter and Einstein-de Sitter models of the universe. This provides an alternative method for probing extra dimension through future GW observations of compact binaries and their electromagnetic counterparts.

  10. Electromagnetic and microwave-absorbing properties of magnetite decorated multiwalled carbon nanotubes prepared with poly(N-vinyl-2-pyrrolidone)

    SciTech Connect

    Zhao, Chunying; Zhang, Aibo; Zheng, Yaping; Luan, Jingfan

    2012-02-15

    Graphical abstract: The Fe{sub 3}O{sub 4}/MWNTs hybrids prepared with PVP achieve a maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below -10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe{sub 3}O{sub 4}/MWNTs hybrids have better absorption properties in the high-frequency range. Highlight: Black-Right-Pointing-Pointer The Fe{sub 3}O{sub 4} decorated MWNTs hybrids were prepared using PVP as dispersant. Black-Right-Pointing-Pointer Many more Fe{sub 3}O{sub 4} particles were attached homogeneously on the surface of MWNTs. Black-Right-Pointing-Pointer The Fe{sub 3}O{sub 4}/MWNTs hybrids achieve a maximum reflection loss of -35.8 dB at 8.56 GHz. Black-Right-Pointing-Pointer A new reflection loss peak occurs at the high-frequency of 14.6 GHz. -- Abstract: The magnetite (Fe{sub 3}O{sub 4}) decorated multiwalled carbon nanotubes (MWNTs) hybrids were prepared by an in situ chemical precipitation method using poly(N-vinyl-2-pyrrolidone) (PVP) as dispersant. The structure and morphology of hybrids are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron-microscopy (TEM). The TEM investigation shows that the Fe{sub 3}O{sub 4}/MWNTs hybrids exhibit less entangled structure and many more Fe{sub 3}O{sub 4} particles are attached homogeneously on the surface of MWNTs, which indicated that PVP can indeed help MWNTs to disperse in isolated form. The electromagnetic and absorbing properties were investigated in a frequency of 2-18 GHz. The results show that the Fe{sub 3}O{sub 4}/MWNTs hybrids exhibit a superparamagnetic behavior and possess a saturation magnetization of 22.9 emu/g. The maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below -10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe{sub 3}O{sub 4}/MWNTs

  11. Effect exerted by a radio wave electromagnetic field on the rheological properties of water and portland-cement systems

    NASA Astrophysics Data System (ADS)

    Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Koshevar, V. D.; Shkadretsova, V. G.; Goncharik, S. V.; Chubrik, N. I.; Orlovich, A. I.

    2013-09-01

    We have studied the effect of the regimes of high-frequency (radio wave) electromagnetic treatment of gauging water on the process of structurization and on the technological characteristics of portland-cement systems. It has been established that the radio wave electromagnetic activation of water leads to a reduction in its surface tension, dynamic viscosity, and shear stress, as well as intensifies the formation of coagulation structures in a portlandcement slurry and aids in increasing the mobility of cement-sand mixtures.

  12. Self-Propagating Combustion Triggered Synthesis of 3D Lamellar Graphene/BaFe12O19 Composite and Its Electromagnetic Wave Absorption Properties

    PubMed Central

    Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Peng, Xiarong; Duan, Shichang; Dang, Alei; Li, Hao; Li, Tiehu

    2017-01-01

    The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self-propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (< −10 dB). The 3D lamellar graphene structures could consume the incident waves through multiple reflection and scattering within the layered structures, prolonging the propagation path of electromagnetic waves in the absorbers. PMID:28336889

  13. ULF Wave Electromagnetic Energy Flux into the Ionosphere: Joule Heating Implications

    NASA Astrophysics Data System (ADS)

    Hartinger, M.; Moldwin, M.; Zou, S.; Bonnell, J. W.; Angelopoulos, V.

    2014-12-01

    Ultra Low Frequency (ULF) waves - such as standing Alfven waves - are one mechanism for coupling the inner magnetosphere to the Earth's ionosphere. For example, they transfer energy from the solar wind or ring current into the Earth's ionosphere via Joule heating. In this study, we use NASA Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite data to investigate the spatial, frequency, and geomagnetic activity dependence of the ULF wave Poynting vector (electromagnetic energy flux) mapped to the ionosphere. We use these measurements to estimate Joule heating rates. We compare these rates to empirical models of Joule heating associated with large scale, static (on ULF wave timescales) current systems, finding that ULF waves usually contribute little to the global, integrated Joule heating rate. However, there are extreme cases when ULF waves make significant contributions to global Joule heating. Finally, we find ULF waves routinely make significant contributions to local Joule heating rates near the noon and midnight local time sectors, where static current systems nominally contribute less to Joule heating; the most important contributions come from lower frequency (<7 mHz) waves.

  14. A new electromagnetic acoustic transducer design for generating torsional guided wave modes for pipe inspections

    NASA Astrophysics Data System (ADS)

    Hill, Samuel; Dixon, Steve; Sri Harsha Reddy, K.; Rajagopal, Prabhu; Balasubramaniam, Krishnan

    2017-02-01

    Guided waves inspection is a well-established method for the long-range ultrasonic inspection of pipes. Guided waves, used in a pulse-echo arrangement, can inspect a large range of the pipe from a single point as the pipe structure carries the waves over a large distance due to the relatively low attenuation of the wave modes. However, the complexity of the dispersion characteristics of these pipe guided wave modes are well known, and can lead to diffculty interpreting the obtained results. The torsional family of guided wave modes are generally considered to have much simpler dispersion characteristics; especially the fundamental T(0,1) mode, which is nominally non-dispersive, making it particularly useful for guided wave inspection. Torsional waves have been generated by a circumferential ring of transducers to approximate an axi-symmetric load to excite this T(0, 1) mode. Presented here is a new design of Electromagnetic Acoustic Transducer (EMAT) that can generate a T(0, 1) as a single transducer, rather than a circumferential array of transducers that all need to be excited in order to generate an axisymmetric force. The EMAT consists of a periodic permanent magnet array and a single meander coil, meaning that the excitation of the torsional mode is greatly simplified. The design parameters of this new EMAT are explored, and the ability to detect notch defects on a pipe is demonstrated.

  15. Modulation and filamentation instability of ultrarelativistic electromagnetic waves in electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Rozina, Ch.; Tsintsade, N. L.; Maryam, N.; Komal, S.

    2016-11-01

    In this study, we have analytically investigated the effects of nonlinear Landau damping on the temporal growth rate of modulation and filamentation instabilities. Here, the nonlocal nonlinear Landau damping phenomena is appearing due to the nonlinear interaction between ultrarelativistic electromagnetic (UREM) wave (having wave vector normal to the beam) and electron-positron-ion plasma. We found that the ultrarelativistic ponderomotive force is linear, while usually it is nonlinear in relativistic case. We construct three dimensional kinetic nonlinear Schrödinger equation for a slowly varying spatio and temporal amplitude of UREM waves. The equations are then Fourier analyzed to obtain dispersion relation, which admit both modulation and filamentation instabilities. It is shown that nonlinear Landau damping is the main source of modulation instability, for a particular condition taking into account later one the maximum growth rate of modulation instability obtained as a function of amplitude of UREM waves and is displayed graphically. Further, it is shown that for an oscillating density profile, plane wave of uniform intensity becomes unstable and gets filamented. Growth rate of stationary state filament is found to be a function of amplitude of UREM waves and is emphasized that the maximum value of growth rate of filamentation instability is further increased in the presence of nonlinear Landau damping term. Finally, the growth rate of non stationary state filamentation instability is calculated and is shown that the characteristic growth length increases both with perpendicular wave vector and the amplitude of UREM waves.

  16. Scattering of relativistic and ultra-relativistic electrons by obliquely propagating Electromagnetic Ion Cyclotron waves

    NASA Astrophysics Data System (ADS)

    Uzbekov, Bogdan; Shprits, Yuri Y.; Orlova, Ksenia

    2016-10-01

    Electromagnetic Ion Cyclotron (EMIC) waves are transverse plasma waves that are generated in the Earth magnetosphere by ring current protons with temperature anisotropy in three different bands: below the H+, He+ and O+ ion gyrofrequencies. EMIC events are enhanced during the main phase of a geomagnetic storm when intensifications in the electric field result in enhanced injections of ions and are usually confined to high-density regions just inside the plasmapause or within drainage plumes. EMIC waves are capable of scattering radiation belt electrons and thus provide an important link between the intensification of the electric field, ion populations, and radiation belt electrons. Bounce-averaged diffusion coefficients computed with the assumption of parallel wave propagation are compared to the results of the code that uses the full cold plasma dispersion relation taking into account oblique propagation of waves and higher-order resonances. We study the sensitivity of the scattering rates to a number of included higher-order resonances, wave spectral distribution parameters, wave normal angle distribution parameters, ambient plasma density, and ion composition. Inaccuracies associated with the neglect of higher-order resonances and oblique propagation of waves are compared to potential errors introduced by uncertainties in the model input parameters.

  17. Development of an electromagnetic acoustic transducer (EMAT) for the noncontact excitation of guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Fromme, P.

    2015-03-01

    Fatigue damage can develop in aerospace structures at locations of stress concentration, such as fasteners. For the safe operation of the aircraft fatigue cracks need to be detected before reaching a critical length. Guided ultrasonic waves offer an efficient method for the detection and characterization of such defects in large aerospace structures. Noncontact excitation of guided waves was achieved using electromagnetic acoustic transducers (EMAT). The transducer development for the specific excitation of the A0 Lamb wave mode is explained. The radial and angular dependency of the excited guided wave pulses at different frequencies were measured using a noncontact laser interferometer. Based on the induced eddy currents in the plate a theoretical model was developed and reasonably good agreement with the measured transducer performance was achieved. The developed transducers were employed for defect detection in aluminum components using fully noncontact guided wave measurements. Excitation of the A0 Lamb wave mode was achieved using the developed EMAT transducer and the guided wave propagation and scattering was measured using a noncontact laser interferometer. These results provide the basis for the defect characterization in aerospace structures using noncontact guided wave sensors.

  18. THE ROLE OF SUPERLUMINAL ELECTROMAGNETIC WAVES IN PULSAR WIND TERMINATION SHOCKS

    SciTech Connect

    Amano, Takanobu; Kirk, John G.

    2013-06-10

    The dynamics of a standing shock front in a Poynting-flux-dominated relativistic flow is investigated by using a one-dimensional, relativistic, two-fluid simulation. An upstream flow containing a circularly polarized, sinusoidal magnetic shear wave is considered, mimicking a wave driven by an obliquely rotating pulsar. It is demonstrated that this wave is converted into large-amplitude electromagnetic waves with superluminal phase speeds by interacting with the shock when the shock-frame frequency of the wave exceeds the proper plasma frequency. The superluminal waves propagate in the upstream, modify the shock structure substantially, and form a well-developed precursor region ahead of a subshock. Dissipation of Poynting flux occurs in the precursor as well as in the downstream region through a parametric instability driven by the superluminal waves. The Poynting flux remaining in the downstream region is carried entirely by the superluminal waves. The downstream plasma is therefore an essentially unmagnetized, relativistically hot plasma with a non-relativistic flow speed, as suggested by observations of pulsar wind nebulae.

  19. Effects of silicic spheres for the suppression of radiation heating using on electromagnetic wave scattering theory

    NASA Astrophysics Data System (ADS)

    Ohkawa, E.; Mikada, H.; Goto, T.; Takekawa, J.; Onishi, K.; Taniguchi, K.; Ashida, Y.

    2009-12-01

    The temperature of external materials of buildings rises when they are exposed to sunlight, and the room temperature rises too if the buildings’ external wall is in the sunlight. Therefore the crisis of electric power supply is frequently caused by air conditioning in midsummer. Recently, it has been experimentally confirmed that such temperature rising of such building materials may be suppressed when they are coated with paint including fine silicic spheres whose diameters are in micron to submicron scale. So we are able to reduce the energy consumption if room temperature is controlled not with any air conditioning but with these paints, and the heat island effects would be lowered. However, the mechanism of this temperature suppression has not been investigated. Experimental consideration of this paint has been done, but the mechanism how the paint controls the temperature rise has hardly been clarified theoretically. Since the best composition of the spheres and their best size are not understood well, it is necessary to theoretically clarify the controlling mechanism for the temperature rise to develop efficient paint. In this study, we aimed to find out the mechanism of the temperature suppression. When the electromagnetic wave at a frequency near eigenfrequencies of atoms, molecules or bindings enters the atoms or the molecules, they resonate and move intensely, and finally rise the temperature. Therefore, we presume that the temperature rise could be controlled if the electromagnetic waves around the eigenfrequencies could be removed. Here, we consider electromagnetic wave of light. Then we assumed that the electromagnetic waves in a certain range of frequencies were scattered to shield the radiated heat energy in the insolation and that the transmitted light through the paint layer is weakened. For verifying the hypotheses and finding the range of effective size, we used the Mie theory of a light scattering theory to calculate the intensity of scattered

  20. Experimental demonstration of broadband reflectionless diffraction-free electromagnetic wave routing

    NASA Astrophysics Data System (ADS)

    Zhang, Youming; Gao, Zhen; Gao, Fei; Shi, Xihang; Xu, Hongyi; Luo, Yu; Zhang, Baile

    2016-12-01

    Wave diffraction is fundamentally difficult to overcome in the routing and interconnection of photonic signals. Although the phenomenon of reflectionless transport through sharp corners in a routing path has been realized in many previous demonstrations, wave diffraction does not allow them to transport deep-subwavelength information or sub-diffraction-limited images. Recent advances in ɛ -near-zero and anisotropic ɛ -near-infinity metamaterials have provided unique possibilities of achieving reflectionless diffraction-free electromagnetic wave routing, but their designs are fundamentally limited to narrow bandwidths, and they have not been demonstrated in reality. Here we experimentally demonstrate broadband reflectionless diffraction-free routing of electromagnetic waves through two right-angled sharp corners in a bent microwave rectangular waveguide. An image with deep-subwavelength information is transported through the bent waveguide in a broad bandwidth. This Rapid Communication supplements and extends the current studies of metamaterials with extreme permittivities and can be useful for routing and interconnection of subwavelength photonic information.

  1. Three-dimensional Fréchet sensitivity kernels for electromagnetic wave propagation

    SciTech Connect

    Strickland, C. E.; Johnson, T. C.; Odom, R. I.

    2015-08-28

    Electromagnetic imaging methods are useful tools for monitoring subsurface changes in pore-fluid content and the associated changes in electrical permittivity and conductivity. The most common method for georadar tomography uses a high frequency ray-theoretic approximation that is valid when material variations are sufficiently small relative to the wavelength of the propagating wave. Georadar methods, however, often utilize electromagnetic waves that propagate within heterogeneous media at frequencies where ray theory may not be applicable. In this paper we describe the 3-D Fréchet sensitivity kernels for EM wave propagation. Various data functional types are formulated that consider all three components of the electric wavefield and incorporate near-, intermediate-, and far-field contributions. We show that EM waves exhibit substantial variations for different relative source-receiver component orientations. The 3-D sensitivities also illustrate out-of-plane effects that are not captured in 2-D sensitivity kernels and can influence results obtained using 2-D inversion methods to image structures that are in reality 3-D.

  2. A Lanczos model-order reduction technique to efficiently simulate electromagnetic wave propagation in dispersive media

    NASA Astrophysics Data System (ADS)

    Zimmerling, Jörn; Wei, Lei; Urbach, Paul; Remis, Rob

    2016-06-01

    In this paper we present a Krylov subspace model-order reduction technique for time- and frequency-domain electromagnetic wave fields in linear dispersive media. Starting point is a self-consistent first-order form of Maxwell's equations and the constitutive relation. This form is discretized on a standard staggered Yee grid, while the extension to infinity is modeled via a recently developed global complex scaling method. By applying this scaling method, the time- or frequency-domain electromagnetic wave field can be computed via a so-called stability-corrected wave function. Since this function cannot be computed directly due to the large order of the discretized Maxwell system matrix, Krylov subspace reduced-order models are constructed that approximate this wave function. We show that the system matrix exhibits a particular physics-based symmetry relation that allows us to efficiently construct the time- and frequency-domain reduced-order models via a Lanczos-type reduction algorithm. The frequency-domain models allow for frequency sweeps meaning that a single model provides field approximations for all frequencies of interest and dominant field modes can easily be determined as well. Numerical experiments for two- and three-dimensional configurations illustrate the performance of the proposed reduction method.

  3. Noncontact excitation of guided waves (A0 mode) using an electromagnetic acoustic transducer (EMAT)

    NASA Astrophysics Data System (ADS)

    Fromme, Paul

    2016-02-01

    Fatigue damage can develop in aircraft structures at locations of stress concentration, such as fasteners, and has to be detected before reaching a critical size to ensure safe aircraft operation. Guided ultrasonic waves offer an efficient method for the detection and characterization of such defects in large aerospace structures. Electromagnetic acoustic transducers (EMAT) for the noncontact excitation of guided ultrasonic waves were developed. The transducer development for the specific excitation of the A0 Lamb wave mode with an out-of-plane Lorentz force is explained. The achieved radial and angular dependency of the excited guided wave pulses were measured using a noncontact laser interferometer. Based on the induced eddy currents in the plate a theoretical model was developed. The application of the developed transducers for defect detection in aluminum components using fully noncontact guided wave measurements was demonstrated. Excitation of the A0 Lamb wave mode was achieved using the developed EMAT transducer and the guided wave propagation and scattering was measured using a noncontact laser interferometer.

  4. Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

    SciTech Connect

    Foteinopoulou, Stavroula

    2003-01-01

    In this dissertation, they have undertaken the challenge to understand the unusual propagation properties of the photonic crystal (PC). The photonic crystal is a medium where the dielectric function is periodically modulated. These types of structures are characterized by bands and gaps. In other words, they are characterized by frequency regions where propagation is prohibited (gaps) and regions where propagation is allowed (bands). In this study they focus on two-dimensional photonic crystals, i.e., structures with periodic dielectric patterns on a plane and translational symmetry in the perpendicular direction. They start by studying a two-dimensional photonic crystal system for frequencies inside the band gap. The inclusion of a line defect introduces allowed states in the otherwise prohibited frequency spectrum. The dependence of the defect resonance state on different parameters such as size of the structure, profile of incoming source, etc., is investigated in detail. For this study, they used two popular computational methods in photonic crystal research, the Finite Difference Time Domain method (FDTD) and the Transfer Matrix Method (TMM). The results for the one-dimensional defect system are analyzed, and the two methods, FDTD and TMM, are compared. Then, they shift their attention only to periodic two-dimensional crystals, concentrate on their band properties, and study their unusual refractive behavior. Anomalous refractive phenomena in photonic crystals included cases where the beam refracts on the ''wrong'' side of the surface normal. The latter phenomenon, is known as negative refraction and was previously observed in materials where the wave vector, the electric field, and the magnetic field form a left-handed set of vectors. These materials are generally called left-handed materials (LHM) or negative index materials (NIM). They investigated the possibility that the photonic crystal behaves as a LHM, and how this behavior relates with the observed

  5. Hollow-spherical composites of Polyaniline/Cobalt Sulfide/Carbon nanodots with enhanced magnetocapacitance and electromagnetic wave absorption capabilities

    NASA Astrophysics Data System (ADS)

    Ge, Chuanjun; Zhang, Xiang; Liu, Jian; Jin, Feng; Liu, Jichang; Bi, Hong

    2016-08-01

    Hollow-spherical composites of polyaniline/cobalt sulfide/carbon nanodots (PANI/CoS/CDs-0.5T) have been synthesized by in situ polymerization under an applied magnetic field (MF) of 0.5 T. As a control, PANI/CoS/CDs-0T composites have been synthesized without a MF. Both composites acting as electrodes present obvious magnetocapacitances at a scan rate of 100 mV s-1 while the electrochemical cell tested under an external MF of 0.5 T. Notably, PANI/CoS/CDs-0.5T composites show larger magnetocapacitances than PANI/CoS/CDs-0T composites at different scan rates from 5 to 100 mV s-1. Electrochemical impedance spectroscopy (EIS) results indicate that MF can reduce charge transfer resistance at electrode/electrolyte interface. More importantly, PANI/CoS/CDs-0.5T composites show a much stronger electromagnetic wave (EMW) absorbing capability than PANI/CoS/CDs-0T in the range of 2-18 GHz which is attributed to an increased dielectric loss and a magnetic loss in low frequency range of 2-12.5 GHz. MF-induced ferromagnetic nanodomains of Co2+ clusters in the PANI/CoS/CDs-0.5T composites increase the complex permittivity and create more interfacial polarizations or the Maxwell-Wagner effect, which leads to increased dielectric loss. Compared with PANI/CoS/CDs-0T composites with diamagnetic behaviour, MF-induced weak ferromagnetism of CoS in the PANI/CoS/CDs-0.5T composites has caused additional magnetic loss. This work provides an efficient way for modulating electrochemical or electromagnetic properties of inorganic/polymer nanocomposites by employing an external MF.

  6. Electromagnetic scattering by underground targets using the cylindrical-wave approach

    NASA Astrophysics Data System (ADS)

    Frezza, Fabrizio; Pajewski, Lara; Ponti, Cristina; Schettini, Giuseppe

    2010-05-01

    The electromagnetic detection of buried cylindrical targets, as structures encountered in the inspection of archaeological sites, or pipes, conduits, and tunnels, has been recently addressed in several works. The development of techniques for investigating cylindrical inhomogeneities embedded in a dielectric medium, is a challenging topic also in several other applications, including non-destructive evaluation and testing in civil engineering, and medical imaging. Ground-penetrating radars (GPRs) are extremely useful in probing subsurface targets through electromagnetic waves. These tools solve an inverse problem, to estimate the electromagnetic properties of a target from field measurements. Different algorithms are employed to post-process the collected experimental data: most of them need a fast and accurate forward solver, to perform repeated evaluations of the scattered field due to known targets, and to be used in combination with some optimization techniques. In this paper, we present an efficient spectral-domain method that we developed for the solution of the two-dimensional electromagnetic plane-wave forward scattering by a finite set of perfectly-conducting or dielectric cylinders, buried in a dielectric half-space or in a finite-thickness slab. The technique is called Cylindrical-Wave Approach (CWA), because the field scattered by the targets is represented in terms of a superposition of cylindrical waves. Use is made of the plane-wave spectrum to take into account the interaction of such waves with the planar interfaces. Suitable reflected and transmitted cylindrical functions are defined; adaptive integration procedures of Gaussian type, together with acceleration algorithms, are employed for the numerical solution of the relevant spectral integrals. All the multiple-reflection phenomena are taken into account. The method may deal with both TM and TE polarization fields; it can be applied for arbitrary values of permittivity, radius, and depth, of the

  7. Monitoring dynamic reactions of red blood cells to UHF electromagnetic waves radiation using a novel micro-imaging technology.

    PubMed

    Ruan, Ping; Yong, Junguang; Shen, Hongtao; Zheng, Xianrong

    2012-12-01

    Multiple state-of-the-art techniques, such as multi-dimensional micro-imaging, fast multi-channel micro-spetrophotometry, and dynamic micro-imaging analysis, were used to dynamically investigate various effects of cell under the 900 MHz electromagnetic radiation. Cell changes in shape, size, and parameters of Hb absorption spectrum under different power density electromagnetic waves radiation were presented in this article. Experimental results indicated that the isolated human red blood cells (RBCs) do not have obviously real-time responses to the ultra-low density (15 μW/cm(2), 31 μW/cm(2)) electromagnetic wave radiation when the radiation time is not more than 30 min; however, the cells do have significant reactions in shape, size, and the like, to the electromagnetic waves radiation with power densities of 1 mW/cm(2) and 5 mW/cm(2). The data also reveal the possible influences and statistical relationships among living human cell functions, radiation amount, and exposure time with high-frequency electromagnetic waves. The results of this study may be significant on protection of human being and other living organisms against possible radiation affections of the high-frequency electromagnetic waves.

  8. Searching for electromagnetic counterpart of LIGO gravitational waves in the Fermi GBM data with ADWO

    NASA Astrophysics Data System (ADS)

    Bagoly, Zsolt; Szécsi, Dorottya; Balázs, Lajos G.; Csabai, István; Horváth, István; Dobos, László; Lichtenberger, János; Tóth, L. Viktor

    2016-09-01

    Aims: The Fermi collaboration identified a possible electromagnetic counterpart of the gravitational wave event of September 14, 2015. Our goal is to provide an unsupervised data analysis algorithm to identify similar events in Fermi's Gamma-ray Burst Monitor CTTE data stream. Methods: We are looking for signals that are typically weak. Therefore, they can only be found by a careful analysis of count rates of all detectors and energy channels simultaneously. Our Automatized Detector Weight Optimization (ADWO) method consists of a search for the signal, and a test of its significance. Results: We developed ADWO, a virtual detector analysis tool for multi-channel multi-detector signals, and performed successful searches for short transients in the data-streams. We have identified GRB150522B, as well as possible electromagnetic candidates of the transients GW150914 and LVT151012. Conclusions: ADWO is an independently developed, unsupervised data analysis tool that only relies on the raw data of the Fermi satellite. It can therefore provide a strong, independent test to any electromagnetic signal accompanying future gravitational wave observations.

  9. Statistical study of seismo-electromagnetic perturbations observed by the DEMETER wave instruments

    NASA Astrophysics Data System (ADS)

    Pisa, David; Santolik, Ondrej; Parrot, Michel

    We present a statistical study of electromagnetic perturbations in the upper ionosphere observed by the DEMETER satellite (launched in 2004, altitude of orbit about 660 km, still operating). Data intervals measured within 330 km from large (M¿=5.0) surface (depth¡40 km) earthquakes are analyzed. Time intervals spanning from 5 days before to 3 days after the main shock are checked for the presence of seismo-electromagnetic effects, while the other data from the same geographical location are used in order to estimate the common, seismically unperturbed, background. Previous results in the VLF range (20 Hz -18 kHz) have shown that there is a statistically significant decrease of wave intensity shortly (less than 4 hours) before the time of the main shock. In this study all the available DEMETER data are used and all the frequency range from ULF to HF (DC -3.175 MHz) is covered. Various types of electromagnetic waves that could be responsible for this effect are discussed, as well as its dependence on the focal mechanism of an imminent earthquake.

  10. Heating patterns in biological tissue phantoms caused by millimeter wave electromagnetic irradiation.

    PubMed

    Khizhnyak, E P; Ziskin, M C

    1994-09-01

    Distribution of millimeter wavelength electromagnetic energy absorption in surface layers of biological tissue models was studied using methods of Infrared Thermography. 0.1 mm thin-layer phantoms were irradiated in the near field using different types of horn antennas in the 37-78 GHz frequency range. Heating patterns were recorded during microwave irradiation, and surface SAR distributions were calculated. The temperature resolution was better than 0.05 K. It was found that horn antennas produced nonuniform heating patterns in irradiated objects. These nonuniform patterns were due to a geometrical resonance resulting from a secondary wave-mode interaction between an irradiated object and the corresponding critical cross-section of the horn antenna. Local SAR values in hot spots exceeded the spatially averaged values by over 10 times, and the widths of these hot spots at 5 times the average SAR were often 1 mm or less. The location, quantity, number and size of the local field absorption maxima of irradiated objects strongly depended on the frequency of electromagnetic irradiation, with equivalent Q-factors of 500 or more. These findings provide an explanation for a number of frequency-dependent effects of millimeter wave electromagnetic irradiation.

  11. Generation of ELF and ULF electromagnetic waves by modulated heating of the ionospheric F2 region

    NASA Astrophysics Data System (ADS)

    Eliasson, B.; Chang, C.-L.; Papadopoulos, K.

    2012-10-01

    We present a theoretical and numerical study of the generation of extremely low frequency (ELF) and ultra-low frequency (ULF) waves by the modulation of the electron pressure at the F2-region with an intense high-frequency electromagnetic wave. The study is based on a cold plasma Hall-MHD model, including electron-neutral and ion-neutral collisions, which governs the dynamics of magnetostatic waves and their propagation through the ionospheric layers. Magnetosonic waves generated in the F2 region are propagating isotropically and are channeled in the ionospheric waveguide, while shear Alfvén waves are propagating along the magnetic field. To penetrate the ionosphere from the F2 peak at 300 km to the ground, the magnetostatic waves first propagate as magnetosonic or shear Alfvén waves that encounter a diffusive layer from about 150 km to 120 km where the Pedersen conductivity dominates, and then as helicon (whistler-like) mode waves from about 120 km to 80 km where the ions are collisionally glued to the neutrals and the Hall conductivity dominates. By performing numerical simulations and studying the dispersive properties of the wave modes, we investigate the dynamics and penetration of ELF/ULF waves through the ionospheric layers to the ground and along the geomagnetic field lines to the magnetosphere. Realistic profiles of the ionospheric profiles of conductivity and density are used, together with different configurations of the geomagnetic field, relevant for both the high, mid and equatorial latitudes. Some of the results are compared with recent HAARP experiments.

  12. Non-Abelian evolution of electromagnetic waves in a weakly anisotropic inhomogeneous medium

    NASA Astrophysics Data System (ADS)

    Bliokh, K. Yu.; Frolov, D. Yu.; Kravtsov, Yu. A.

    2007-05-01

    A theory of electromagnetic wave propagation in a weakly anisotropic smoothly inhomogeneous medium is developed, based on the quantum-mechanical diagonalization procedure applied to Maxwell equations. The equations of motion for the translational (ray) and intrinsic (polarization) degrees of freedom are derived ab initio. The ray equations take into account the optical Magnus effect (spin Hall effect of photons) as well as trajectory variations owing to the medium anisotropy. Polarization evolution is described by the precession equation for the Stokes vector. In the generic case, the evolution of wave turns out to be non-Abelian: it is accompanied by mutual conversion of the normal modes and periodic oscillations of the ray trajectories analogous to electron zitterbewegung. The general theory is applied to examples of wave evolution in media with circular and linear birefringence.

  13. Selecting Gravitational Wave Candidates for Electromagnetic Follow-up: Advanced LIGO/Virgo's Decision Making Process

    NASA Astrophysics Data System (ADS)

    Cho, Min-A.; LIGO Scientific Collaboration; Virgo Collaboration

    2016-03-01

    Some of the most violent events in the universe are bright in both their gravitational wave (GW) emission and electromagnetic (EM). This means that prospects for multi-messenger astronomy increase as more and more detectors join the search for gravitational waves. Here I present the protocol created by members of Advanced LIGO/Virgo's EM Follow-up Program which ultimately results in alerting its astronomy partners or not. I discuss the series of checks and questions performed by humans (follow-up advocates and control room personnel) and automated online software (Approval Processor). This talk will follow the fate of the gravitational wave candidate event after it first enters Advanced LIGO/Virgo's online candidate event database. We gratefully acknowledge the support of the U.S. National Science Foundation through Grant PHY-1404121.

  14. Studies of electromagnetic ion cyclotron waves using AMPTE/CCE and dynamics explorer

    NASA Technical Reports Server (NTRS)

    Erlandson, Robert E.

    1994-01-01

    The overall objective of this research is to investigate the generation and propagation of electromagnetic ion cyclotron (EMIC) waves in the frequency range from 0.2 to 5 Hz (Pc 1 frequency band). Data used in this research were acquired by the AMPTE/CCE, DE-1, and DE-2 satellites. One of the primary questions addressed in this research is the role which EMIC waves have on the transfer of energy from the equatorial magnetosphere to the ionosphere. The primary result from this research is that some fraction of EMIC waves, generated in the equatorial magnetosphere, are Landau damped in the ionosphere and are therefore a heat source for ionospheric electrons. This result as well as other results are summarized below.

  15. Non-Abelian evolution of electromagnetic waves in a weakly anisotropic inhomogeneous medium

    SciTech Connect

    Bliokh, K. Yu.; Frolov, D. Yu.; Kravtsov, Yu. A.

    2007-05-15

    A theory of electromagnetic wave propagation in a weakly anisotropic smoothly inhomogeneous medium is developed, based on the quantum-mechanical diagonalization procedure applied to Maxwell equations. The equations of motion for the translational (ray) and intrinsic (polarization) degrees of freedom are derived ab initio. The ray equations take into account the optical Magnus effect (spin Hall effect of photons) as well as trajectory variations owing to the medium anisotropy. Polarization evolution is described by the precession equation for the Stokes vector. In the generic case, the evolution of wave turns out to be non-Abelian: it is accompanied by mutual conversion of the normal modes and periodic oscillations of the ray trajectories analogous to electron zitterbewegung. The general theory is applied to examples of wave evolution in media with circular and linear birefringence.

  16. Frequency changes of electromagnetic waves in simple polar-molecule reactions

    NASA Astrophysics Data System (ADS)

    Liu, Xingpeng; Huang, Kama

    2017-03-01

    Characteristics of electromagnetic wave (EMW) propagation in microwave-assisted chemical reactions are critical to solve the problems of inhomogeneous heating and thermal runaway. By transforming the propagation equation of EMWs in simple polar-molecule reactions, the dispersive and time-varying characteristics of simple polar-molecule reactions are unfolded. Subsequently, we simulate the propagation of EMWs in simple polar-molecule reactions to disclose the effects of component concentration variation on frequency changes. Frequency changes can be neglected during the process of component concentration variation on the condition that the time scale of the variation is much greater than the wave period. If the time scale of the variation is comparable with or smaller than the wave period, frequency broadening or shift can be observed. Frequency changes are used to discuss the relationship between the time domain and frequency domain representation of the polarization in the reactions.

  17. Electromagnetic wave absorption properties of NiCoP alloy nanoparticles decorated on reduced graphene oxide nanosheets

    NASA Astrophysics Data System (ADS)

    Ye, Weichun; Fu, Jiajia; Wang, Qin; Wang, Chunming; Xue, Desheng

    2015-12-01

    NiCoP alloy nanoparticles supported on reduced graphene oxide (NiCoP/RGO) are synthesized by in situ co-reduction of Ni2+, Co2+ and graphene oxide (GO) with sodium hypophosphite in a one-pot reaction. This synthesis route is simple and can be used for industrial preparation. The different molar ratios of Ni/Co can be obtained by changing the molar ratio of their salts in the reaction bath. The effect of annealing temperature on the crystal structure of NiCoP alloys has been further investigated. After 500 °C annealing, NiCoP alloys exhibit good crystallinity. The as-prepared NiCoP/RGO composites demonstrate high dielectric constant and magnetic loss in the frequency range of 2-18 GHz due to the conductive and ferromagnetic behavior. Also, their coercivity and magnetization strength are decreased from magnetic measurement with the increase of Ni content. As the molar ratio of Ni/Co is 3:1, the maximum value of the reflection loss reaches to -17.84 dB. Furthermore, the NiCoP/RGO composites have better corrosion resistance than traditional iron series magnetic nanoparticles. It is expected that the composites with the thin, light-weighted and broadband absorbing and good anti-corrosion properties will have a great potential for electromagnetic wave absorption applications.

  18. Bursty, Broadband Electromagnetic Waves Associated with Three-Dimensional Nulls Observed in Turbulent Magnetosheath Reconnection

    NASA Technical Reports Server (NTRS)

    Adrian, Mark L.; Wendel, D. E.

    2012-01-01

    We investigate observations of intense bursts of electromagnetic wave energy in association with the thin current layers of turbulent magnetosheath reconnection. These observed emissions - typically detected in the layers immediately outside of the current layer proper - form two distinct types: (i) broadband emissions that extend continuously to lOs of Hertz; and (ii) structured bursts of emitted energy that occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed near the local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic energy and quantify their proximity to X-IO-nulls and magnetic spine connected null pairs, as well as their correlation - if any - to the amount of magnetic energy converted by the process of magnetic reconnection.

  19. Singularities in the Transverse Fields of Electromagnetic Waves. II. Observations on the Electric Field

    NASA Astrophysics Data System (ADS)

    Hajnal, J. V.

    1987-12-01

    Electromagnetic waves propagating in free space contain three kinds of singularities called C lines, S surfaces and disclinations. The paper describes observations of these singularities in two different monochromatic microwave fields. The observations confirm all the theoretically predicted properties of the singularities that could be tested. As expected, the singularities were found to be prominent structural features of the fields and in consequence to provide an economical means of characterizing their structure. A notable result is the observation of both right-hand and left-hand C lines in a field that is nominally uniformly left-hand circularly polarized. This is in agreement with the previous assertion that, in general, electromagnetic wavefields contain both right-hand and left-hand polarized regions.

  20. Stimulated scattering of electromagnetic waves carrying orbital angular momentum in quantum plasmas.

    PubMed

    Shukla, P K; Eliasson, B; Stenflo, L

    2012-07-01

    We investigate stimulated scattering instabilities of coherent circularly polarized electromagnetic (CPEM) waves carrying orbital angular momentum (OAM) in dense quantum plasmas with degenerate electrons and nondegenerate ions. For this purpose, we employ the coupled equations for the CPEM wave vector potential and the driven (by the ponderomotive force of the CPEM waves) equations for the electron and ion plasma oscillations. The electrons are significantly affected by the quantum forces (viz., the quantum statistical pressure, the quantum Bohm potential, as well as the electron exchange and electron correlations due to electron spin), which are included in the framework of the quantum hydrodynamical description of the electrons. Furthermore, our investigation of the stimulated Brillouin instability of coherent CPEM waves uses the generalized ion momentum equation that includes strong ion coupling effects. The nonlinear equations for the coupled CPEM and quantum plasma waves are then analyzed to obtain nonlinear dispersion relations which exhibit stimulated Raman, stimulated Brillouin, and modulational instabilities of CPEM waves carrying OAM. The present results are useful for understanding the origin of scattered light off low-frequency density fluctuations in high-energy density plasmas where quantum effects are eminent.

  1. Electromagnetic dust-lower-hybrid and dust-magnetosonic waves and their instabilities in a dusty magnetoplasma

    SciTech Connect

    Salimullah, M.; Rahman, M. M.; Zeba, I.; Shah, H. A.; Murtaza, G.; Shukla, P. K.

    2006-12-15

    The electromagnetic waves below the ion-cyclotron frequency have been examined in a collisionless and homogeneous dusty plasma in the presence of a dust beam parallel to the direction of the external magnetic field. The low-frequency mixed electromagnetic dust-lower-hybrid and purely transverse magnetosonic waves become unstable for the sheared flow of dust grains and grow in amplitude when the drift velocity of the dust grains exceeds the parallel phase velocity of the waves. The growth rate depends dominantly upon the thermal velocity and density of the electrons.

  2. Maximizing the probability of detecting an electromagnetic counterpart of gravitational-wave events

    NASA Astrophysics Data System (ADS)

    Coughlin, Michael; Stubbs, Christopher

    2016-10-01

    Compact binary coalescences are a promising source of gravitational waves for second-generation interferometric gravitational-wave detectors such as advanced LIGO and advanced Virgo. These are among the most promising sources for joint detection of electromagnetic (EM) and gravitational-wave (GW) emission. To maximize the science performed with these objects, it is essential to undertake a followup observing strategy that maximizes the likelihood of detecting the EM counterpart. We present a follow-up strategy that maximizes the counterpart detection probability, given a fixed investment of telescope time. We show how the prior assumption on the luminosity function of the electro-magnetic counterpart impacts the optimized followup strategy. Our results suggest that if the goal is to detect an EM counterpart from among a succession of GW triggers, the optimal strategy is to perform long integrations in the highest likelihood regions. For certain assumptions about source luminosity and mass distributions, we find that an optimal time investment that is proportional to the 2/3 power of the surface density of the GW location probability on the sky. In the future, this analysis framework will benefit significantly from the 3-dimensional localization probability.

  3. Atomic layer lithography of wafer-scale nanogap arrays for extreme confinement of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoshu; Park, Hyeong-Ryeol; Pelton, Matthew; Piao, Xianji; Lindquist, Nathan C.; Im, Hyungsoon; Kim, Yun Jung; Ahn, Jae Sung; Ahn, Kwang Jun; Park, Namkyoo; Kim, Dai-Sik; Oh, Sang-Hyun

    2013-09-01

    Squeezing light through nanometre-wide gaps in metals can lead to extreme field enhancements, nonlocal electromagnetic effects and light-induced electron tunnelling. This intriguing regime, however, has not been readily accessible to experimentalists because of the lack of reliable technology to fabricate uniform nanogaps with atomic-scale resolution and high throughput. Here we introduce a new patterning technology based on atomic layer deposition and simple adhesive-tape-based planarization. Using this method, we create vertically oriented gaps in opaque metal films along the entire contour of a millimetre-sized pattern, with gap widths as narrow as 9.9 Å, and pack 150,000 such devices on a 4-inch wafer. Electromagnetic waves pass exclusively through the nanogaps, enabling background-free transmission measurements. We observe resonant transmission of near-infrared waves through 1.1-nm-wide gaps (λ/1,295) and measure an effective refractive index of 17.8. We also observe resonant transmission of millimetre waves through 1.1-nm-wide gaps (λ/4,000,000) and infer an unprecedented field enhancement factor of 25,000.

  4. Electromagnetic wave propagation through a dielectric-chiral interface and through a chiral slab

    NASA Technical Reports Server (NTRS)

    Bassiri, S.; Papas, C. H.; Engheta, N.

    1988-01-01

    The reflection from and transmission through a semiinfinite chiral medium are analyzed by obtaining the Fresnel equations in terms of parallel- and perpendicular-polarized modes, and a comparison is made with results reported previously. The chiral medium is described electromagnetically by the constitutive relations D = (epsilon)E+i(gamma)B and H = i(gamma)E+(1/mu)B. The constants epsilon, mu and gamma are real and have values that are fixed by the size, the shape, and the spatial distribution of the elements that collectively compose the medium. The conditions are obtained for the total internal reflection of the incident wave from the interface and for the existence of the Brewster angle. The effects of the chirality on the polarization and the intensity of the reflected wave from the chiral half-space are discussed and illustrated by using the Stokes parameters. The propagation of electromagnetic wave through an infinite slab of chiral medium is formulated for oblique incidence and solved analytically for the case of normal incidence.

  5. Radial wave crystals: radially periodic structures from anisotropic metamaterials for engineering acoustic or electromagnetic waves.

    PubMed

    Torrent, Daniel; Sánchez-Dehesa, José

    2009-08-07

    We demonstrate that metamaterials with anisotropic properties can be used to develop a new class of periodic structures that has been named radial wave crystals. They can be sonic or photonic, and wave propagation along the radial directions is obtained through Bloch states like in usual sonic or photonic crystals. The band structure of the proposed structures can be tailored in a large amount to get exciting novel wave phenomena. For example, it is shown that acoustical cavities based on radial sonic crystals can be employed as passive devices for beam forming or dynamically orientated antennas for sound localization.

  6. Rotational Doppler shift for electromagnetic waves carrying orbital angular momentum based on spectrum analysis

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Wang, Gang

    2017-03-01

    We investigate the rotational Doppler effect for the electromagnetic wave carrying orbital angular momentum (OAM) with a method based on spectrum analysis, which is appropriate for both optics and free-space radio cases. We find that the frequency spectrum received is the convolution of emission spectrum and a discrete spectrum about OAM states, and verify it in the numerical simulations as well. This discovery makes it possible to distinguish the linear and rotational Doppler shift, and is helpful to developments of remote sensing and velocimetry in radar.

  7. Generation of Low-Frequency Electromagnetic Waves by Spectrally Broad Intense Laser Pulses in a Plasma

    NASA Astrophysics Data System (ADS)

    Tsintsadze, L. N.; Tajima, T.; Nishikawa, K.; Koga, J. K.; Nakagawa, K.; Kishimoto, Y.

    A new mechanism for the emission of low-frequency electromagnetic (EM) waves, including the generation of a quasistatic magnetic field, by a relativistically intense laser pulse with a wide spectrum is presented. The emission is due to modulational and filamentational instabilities of the photon gas in a plasma. The generation of the magnetic field is associated with a significant change in the laser pulse shape during the propagation. This process is identified in our 2D particle-in-cell (PIC) simulations with a high intensity (1019

  8. Millimeter-wave imaging with slab focusing lens made of electromagnetic-induction materials.

    PubMed

    Yang, Kui; Wang, Jinbang; Zhao, Lu; Liu, Zhiguo; Zhang, Tao

    2016-01-11

    A slab focusing lens in this work has been designed, which consists of electromagnetic-induction materials (cage-shaped granules of conductor materials) and polymethyl methacrylate (PMMA) materials. A compound lens with a thickness of 32 mm is composed of two slab focusing lenses, and has a refractive index of 1.41 at 35 GHz. Millimeter-wave (MMW) images of metallic objects have been obtained with the compound lens. The image quality has been compared by means of the compound lens and the polyethylene lens. The experimental results show good feasibility of the compound lens in MMW imaging.

  9. Unconditionally stable WLP-FDTD method for the modeling of electromagnetic wave propagation in gyrotropic materials.

    PubMed

    Li, Zheng-Wei; Xi, Xiao-Li; Zhang, Jin-Sheng; Liu, Jiang-fan

    2015-12-14

    The unconditional stable finite-difference time-domain (FDTD) method based on field expansion with weighted Laguerre polynomials (WLPs) is applied to model electromagnetic wave propagation in gyrotropic materials. The conventional Yee cell is modified to have the tightly coupled current density components located at the same spatial position. The perfectly matched layer (PML) is formulated in a stretched-coordinate (SC) system with the complex-frequency-shifted (CFS) factor to achieve good absorption performance. Numerical examples are shown to validate the accuracy and efficiency of the proposed method.

  10. Very weak solutions of wave equation for Landau Hamiltonian with irregular electromagnetic field

    NASA Astrophysics Data System (ADS)

    Ruzhansky, Michael; Tokmagambetov, Niyaz

    2016-11-01

    In this paper, we study the Cauchy problem for the Landau Hamiltonian wave equation, with time-dependent irregular (distributional) electromagnetic field and similarly irregular velocity. For such equations, we describe the notion of a `very weak solution' adapted to the type of solutions that exist for regular coefficients. The construction is based on considering Friedrichs-type mollifier of the coefficients and corresponding classical solutions, and their quantitative behaviour in the regularising parameter. We show that even for distributional coefficients, the Cauchy problem does have a very weak solution, and that this notion leads to classical or distributional-type solutions under conditions when such solutions also exist.

  11. Electromagnetic plane-wave pulse transmission into a Lorentz half-space.

    PubMed

    Cartwright, Natalie A

    2011-12-01

    The propagation of an electromagnetic plane-wave signal obliquely incident upon a Lorentz half-space is studied analytically. Time-domain asymptotic expressions that increase in accuracy with propagation distance are derived by application of uniform saddle point methods on the Fourier-Laplace integral representation of the transmitted field. The results are shown to be continuous in time and comparable with numerical calculations of the field. Arrival times and angles of refraction are given for prominent transient pulse features and the steady-state signal.

  12. All-dielectric structure development for electromagnetic wave shielding using a systematic design approach

    NASA Astrophysics Data System (ADS)

    Shin, H.; Heo, N.; Park, J.; Seo, I.; Yoo, J.

    2017-01-01

    Common dielectric metamaterials for electromagnetic (EM) interference shielding, stealth applications, and EM cloaking generally require larger thicknesses than the wavelength of incidence light. We propose an all-dielectric metamaterial inspired structure using a systematic approach based on the phase field design method. The structure is composed of periodically arranged unit structures that have a 2D configuration, which is sub-wavelength thick over its entire structure. The proposed structure provides anomalous reflections to prevent reflections back toward the wave source and is anti-penetrative over the microwave band with no conductive materials. We digitally fabricated the designed structure using 3D printing and verified the design specifications by experiments.

  13. Impedance match of long-wavelength electromagnetic waves incident into magnetic photonic crystals.

    PubMed

    Yang, S Y

    2007-06-11

    By utilizing an effective-medium method, the effective dielectric constant and effective magnetic permeability of magnetic photonic crystals at long-wavelength limits were calculated. We also examined the impedance ratio when a long-wavelength electromagnetic wave is incident to a magnetic photonic crystal. In this work, we focus on investigating the impact of the magnetic permeability of rods forming magnetic photonic crystals on the impedance ratio. Furthermore, we analyze the dependencies of the incident angle at impedance match on the magnetic permeability and filling factor of rods.

  14. Very weak solutions of wave equation for Landau Hamiltonian with irregular electromagnetic field

    NASA Astrophysics Data System (ADS)

    Ruzhansky, Michael; Tokmagambetov, Niyaz

    2017-04-01

    In this paper, we study the Cauchy problem for the Landau Hamiltonian wave equation, with time-dependent irregular (distributional) electromagnetic field and similarly irregular velocity. For such equations, we describe the notion of a `very weak solution' adapted to the type of solutions that exist for regular coefficients. The construction is based on considering Friedrichs-type mollifier of the coefficients and corresponding classical solutions, and their quantitative behaviour in the regularising parameter. We show that even for distributional coefficients, the Cauchy problem does have a very weak solution, and that this notion leads to classical or distributional-type solutions under conditions when such solutions also exist.

  15. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Aldrigo, Martino; Dragoman, Mircea; Constanzo, Alessandra; Dragoman, Daniela

    2013-11-01

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  16. Experimental Demonstration of Guiding and Bending of Electromagnetic Waves in a Photonic Crystal

    SciTech Connect

    Chow, E.; Hietala, .; Joannopoulos, J.D.; Lin, S.; Villeneuve, P.R.

    1998-10-15

    The routing and interconnection of optical signals through narrow channels and around sharp corners is important for large-scale all-optical circuit applications. A recent computational result suggests that photonic crystals may offer a novel way of achieving this goal by providing a mechanism for guiding light that is fundamentally different from traditional index guiding. Waveguiding in a photonic crystal, and near 100% transmission of electromagnetic waves around sharp 90o corners were observed experimentally. Bend- ing radii were made smaller than one wavelength.

  17. A class of invisible inhomogeneous media and the control of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Vial, B.; Liu, Y.; Horsley, S. A. R.; Philbin, T. G.; Hao, Y.

    2016-12-01

    We propose a general method to arbitrarily manipulate an electromagnetic wave propagating in a two-dimensional medium, without introducing any scattering. This leads to a whole class of isotropic spatially varying permittivity and permeability profiles that are invisible while shaping the field magnitude and/or phase. In addition, we propose a metamaterial structure working in the infrared that demonstrates deep subwavelength control of the electric field amplitude and strong reduction of the scattering. This work offers an alternative strategy to achieve invisibility with isotropic materials and paves the way for tailoring the propagation of light at the nanoscale.

  18. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    SciTech Connect

    Aldrigo, Martino; Costanzo, Alessandra; Dragoman, Mircea; Dragoman, Daniela

    2013-11-14

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  19. Propagation of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency

    SciTech Connect

    Tian, Yuan; Han, YiPing; Ling, YingJie; Ai, Xia

    2014-02-15

    In this paper, we investigate the absorption spectra of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency. Profiles are introduced to describe the non-uniformity of collision frequency. It is interesting to find that when the plasma is collision frequency inhomogeneous, the absorption spectrum would decreases faster than that in uniform plasma. And the rate of decreasing would be different when the profile changes. Two parameters are set up to predict how the profiles affect the absorption spectra. Furthermore, the effects of electron density are also considered.

  20. Are Ring Current Ions Lost in Electromagnetic Ion Cyclotron Wave Dispersion Relation?

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  1. Effect of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  2. Fabrication and electromagnetic characteristics of microwave absorbers containing Li0.35Zn0.3Fe2.35O4 micro-belts and nickel-coated carbon fibers

    NASA Astrophysics Data System (ADS)

    Zhao, Bin; Wang, Qilei; Zhang, Cunrui

    2013-11-01

    Li0.35Zn0.3Fe2.35O4 micro-belts were prepared by cotton template. The nickel-coated carbon fibers were obtained by electroless plating method. The formation mechanism of the ferrite micro-belt was studied. The electromagnetic properties of the microwave absorbers were investigated in the frequency range of 30-6000 MHz. The double-layer absorbers have better microwave absorption properties than the nickel-coated carbon fibers single-layer absorbers and the microwave absorption properties of the composites are influenced by the thickness of the absorber.

  3. Electromagnetic ion cyclotron waves in the inner magnetosphere with a losscone proton distribution

    NASA Astrophysics Data System (ADS)

    Singh, Satyavir; Omura, Yoshiharu

    2016-07-01

    Electromagnetic ion cyclotron (EMIC) waves are studied in the inner magnetospheric plasma. The plasma is assumed to have five components, i.e., electrons, cold and hot protons, singly charged helium and oxygen ions. The hot protons are assumed to have an anisotropic losscone distribution particle distribution. The numerical results are obtained using KUPDAP (Kyoto University Plasma Dispersion Analysis Package), a full dispersion solver developed at Kyoto University. The hot plasma dispersion relation and polarizations of EMIC waves in oblique propagation are very complex. Although we find that nonlinear wave growth process is dominant near the equatorial region generating EMIC rising tone emissions, the propagation characteristics of the emissions such as linear growth/damping rates, variation of polarizations, and Poynting vectors in the presence of energetic protons have not been studied quantitatively.The growth/damping of oxygen, helium, and proton bands and higher harmonics of the EMIC waves are studied. The findings from our model are applied to EMIC wave observations in the inner magnetosphere by the Cluster spacecraft.

  4. Development and performance evaluation of an electromagnetic-type shock wave generator for lipolysis

    SciTech Connect

    Liang, S. M. Yang, Z. Y.; Chang, M. H.

    2014-01-15

    This study aims at the design and development of electromagnetic-type intermittent shock wave generation in a liquid. The shock wave generated is focused at a focal point through an acoustic lens. This hardware device mainly consists of a full-wave bridge rectifier, 6 capacitors, a spark gap, and a flat coil. A metal disk is mounted in a liquid-filled tube and is placed in close proximity to the flat coil. Due to the repulsive force existing between the coil and disk shock waves are generated, while an eddy current is induced in the metal disk. Some components and materials associated with the device are also described. By increasing the capacitance content to enhance electric energy level, a highly focused pressure can be achieved at the focal point through an acoustic lens in order to lyse fat tissue. Focused pressures were measured at the focal point and its vicinity for different operation voltages. The designed shock wave generator with an energy intensity of 0.0016 mJ/mm{sup 2} (at 4 kV) and 2000 firings or higher energy intensities with 1000 firings is found to be able to disrupt pig fat tissue.

  5. Theoretical study of electromagnetic electron cyclotron waves in the presence of AC field in Uranian magnetosphere

    NASA Astrophysics Data System (ADS)

    Pandey, R. S.; Kaur, Rajbir

    2015-10-01

    Electromagnetic electron cyclotron (EMEC) waves with temperature anisotropy in the magnetosphere of Uranus have been studied in present work. EMEC waves are investigated using method of characteristic solution by kinetic approach, in presence of AC field. In 1986, Voyager 2 encounter with Uranus revealed that magnetosphere of Uranus exhibit non-Maxwellian high-energy tail distribution. So, the dispersion relation, real frequency and growth rate are evaluated using Lorentzian Kappa distribution function. Effect of temperature anisotropy, AC frequency and number density of particles is found. The study is also extended to oblique propagation of EMEC waves in presence and absence of AC field. Through comprehensive mathematical analysis it is found that when EMEC wave propagates parallel to intrinsic magnetic field of Uranus, its growth is more enhanced than in case of oblique propagation. Results are also discussed in context to magnetosphere of Earth and also gives theoretical explanation to existence of high energetic particles observed by Voyager 2 in the magnetosphere of Uranus. The results can present a further insight into the nature of electron-cyclotron instability condition for the whistler mode waves in the outer radiation belts of Uranus or other space plasmas.

  6. Electromagnetic waves with frequencies near the local proton gyrofrequency: ISEE-3 1 AU observations

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Arballo, John K.; Mok, John; Smith, Edward J.; Mason, Glenn M.; Tan, Lun C.

    1994-01-01

    Low Frequency (LF) electromagnetic waves with periods near the local proton gyrofrequency have been detected in interplanetary space by the magnetometer onboard International-Sun-Earth-Explorer-3 (ISEE-3). Transverse peak-to-peak amplitudes as large as delta vector B/absolute value of B approximately 0.4 have been noted with compressional components (Delta absolute value of B/absolute value of B) typically less than or = 0.1. Generally, the waves have even smaller amplitudes, or are not detectable within the solar wind turbulence. The waves are elliptically/linearly polarized and are often, but not always, found to propagate nearly along vector B(sub zero). Both right- and left-hand polarizations in the spacecraft-frame have been detected. The waves are observed during all orientations of the interplanetary magnetic field, with the Parker spiral orientation being the most common case. Because the waves are detected at and near the local proton cyclotron frequency, the generation mechanism must almost certainly be solar wind pickup of freshly created hydrogen ions. Possible sources for the hydrogen are the Earth's atmosphere, coronal mass ejections from the Sun, comets and interstellar neutral atoms. At this time it is not obvious which potential source is the correct one. Statistical tests employing over one year of ISEE-3 data will be done in the near future to eliminate/confirm some of these possibilities.

  7. Simulations of heavy ion heating by electromagnetic ion cyclotron waves driven by proton temperature anisotropies

    NASA Technical Reports Server (NTRS)

    Tanaka, M.

    1985-01-01

    Heating of heavy ions by the electromagnetic ion cyclotron (EMIC) waves, which are driven by proton temperature anisotropies, is studied by means of hybrid particle simulations. Initially, relaxation of the temperature anisotropies in the proton distribution and isotropic heating of the heavy ions are observed (phase I), followed by substantial perpendicular heating of the heavy ions (phase II). The heavy ions are distinctly gyrophase modulated by the EMIC waves. The isotropic heating in phase I is due to magnetic trapping by the excited proton cyclotron waves. The perpendicular heating in phase II is attributed to cyclotron resonance with the EMIC waves, which becomes possible by means of the preceding heating in phase I. Saturation of the EMIC instability is instead attributed to magnetic trapping of the majority ions: protons. When the proton anisotropy is very large, frequency shift (decrease) of the proton cyclotron waves to less than 1/2 Ohm(p) is observed. The present mechanism is not only relevant to He(+) heating in the dayside equator of the magnetosphere, but it also predicts hot He2(+) ions behind the earth's bow shock.

  8. Toward a System-Based Approach to Electromagnetic Ion Cyclotron Waves in Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Gamayunov, K. V.; Engebretson, M. J.; Rassoul, H.

    2015-12-01

    We consider a nonlinear wave energy cascade from the low frequency range into the higher frequency domain of electromagnetic ion cyclotron (EMIC) wave generation as a possible source of seed fluctuations for EMIC wave growth due to the ion cyclotron instability in Earth's magnetosphere. The theoretical analysis shows that energy cascade from the Pc 4-5 frequency range (2-22 mHz) into the range of Pc 1-2 pulsations (0.1-5 Hz) is able to supply the level of seed fluctuations that guarantees growth of EMIC waves up to an observable level during one pass through the near equatorial region where the ion cyclotron instability takes place. We also analyze magnetic field data from the Polar and Van Allen Probes spacecraft to test this nonlinear mechanism. We restrict our analysis to magnetic spectra only. We do not analyze the third-order moment for total energy of the magnetic and velocity fluctuations, but judge whether a nonlinear energy cascade is present or whether it is not by only analyzing the appearance of power-law distributions in the low frequency part of the magnetic field spectra. While the power-law spectrum alone does not guarantee that a nonlinear cascade is present, the power-law distribution is a strong indication of the possible development of a nonlinear cascade. Our data analysis shows that a nonlinear energy cascade is indeed observed in both the outer and inner magnetosphere, and EMIC waves are growing from this nonthermal background. All the analyzed data are in good agreement with the theoretical model presented in this study. Overall, the results of this study support a nonlinear energy cascade in Earth's magnetosphere as a mechanism which is responsible for supplying seed fluctuating energy in the higher frequency domain where EMIC waves grow due to the ion cyclotron instability. Keywords: nonlinear energy cascade, ultra low frequency waves, electromagnetic ion cyclotron waves, seed fluctuationsAcknowledgments: This paper is based upon work

  9. Loop heating by D.C. electric current and electromagnetic wave emissions simulated by 3-D EM particle zone

    NASA Technical Reports Server (NTRS)

    Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.

    1994-01-01

    We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.

  10. Incidental/Absorbed Exposure Electromagnetic Field Energy Ratio Analysis Under Laboratory Experiment Conditions (for Russian-French Immunology Project)

    DTIC Science & Technology

    2007-11-07

    electromagnetic energy of UHF band and their influence in fetus and progeny. Messenger of the USSR Academy of Medical Sciences, Moscow, Medicina ...Homeostasis. – Moscow, Medicina publisher, 1981 – 576 p. In Russian 13. Hygienic challenges of non-ionizing radiation. Edited by Yu.G. Grigoriev and V.S

  11. In Situ Growth of Core-Sheath Heterostructural SiC Nanowire Arrays on Carbon Fibers and Enhanced Electromagnetic Wave Absorption Performance.

    PubMed

    Yan, Liwen; Hong, Changqing; Sun, Boqian; Zhao, Guangdong; Cheng, Yehong; Dong, Shun; Zhang, Dongyang; Zhang, Xinghong

    2017-02-22

    Large-scale core-sheath heterostructural SiC nanowires were facilely grown on the surface of carbon fibers using a one-step chemical vapor infiltration process. The as-synthesized SiC nanowires consist of single crystalline SiC cores with a diameter of ∼30 nm and polycrystalline SiC sheaths with an average thickness of ∼60 nm. The formation mechanisms of core-sheath heterostructural SiC nanowires (SiCnws) were discussed in detail. The SiCnws-CF shows strong electromagnetic (EM) wave absorption performance with a maximum reflection loss value of -45.98 dB at 4.4 GHz. Moreover, being coated with conductive polymer polypyrrole (PPy) by a simple chemical polymerization method, the SiCnws-CF/PPy nanocomposites exhibited superior EM absorption abilities with maximum RL value of -50.19 dB at 14.2 GHz and the effective bandwidth of 6.2 GHz. The SiCnws-CF/PPy nanocomposites in this study are very promising as absorber materials with strong electromagnetic wave absorption performance.

  12. Unusual characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies

    NASA Technical Reports Server (NTRS)

    Brinca, A. L.; Tsurutani, B. T.

    1987-01-01

    The characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies are examined using a model of solar wind permeated by dilute drifting ring distributions of electrons and oxygen ions with finite thermal spreads. The model has parameters compatible with the ICE observations at the Giacobini-Zinner comet. It is shown that cometary newborn ions with large perpendicular energies can excite a wave mode with rest frame frequencies in the order of the heavy ion cyclotron frequency, Omega(i), and unusual propagation characteristics at small obliquity angles. For parallel propagation, the mode is left-hand circularly polarized, might be unstable in a frequency range containing Omega(i), and moves in the direction of the newborn ion drift along the static magnetic field.

  13. Analog electromagnetically induced transparency for circularly polarized wave using three-dimensional chiral metamaterials.

    PubMed

    Lin, Hai; Yang, Dong; Han, Song; Liu, Yangjie; Yang, Helin

    2016-12-26

    In this paper, we theoretically and experimentally demonstrate a three-dimensional metamaterial that can motivate electromagnetic induced transparency (EIT) by using circular polarized wave as stimulations. The unit cell consists of a pair of metallic strips printed on both sides of the printed circuit board (PCB), where a conductive cylinder junction is used to connect the metal strips by drilling a hole inside the substrate. When a right circularly polarized wave is incident, destructive interference is excited between meta-atoms of the 3D structure, the transmission spectrum demonstrates a sharp transparency window. A coupled oscillator model and an electrical equivalent circuit model are applied to quantitatively and qualitatively analyze the coupling mechanism in the EIT-like metamaterial. Analysis in detail shows the EIT window's amplitude and frequency are modulated by changing the degree of symmetry breaking. The proposed metamaterial may achieve potential applications in developing chiral slow light devices.

  14. Analog electromagnetically induced transparency for circularly polarized wave using three-dimensional chiral metamaterials

    NASA Astrophysics Data System (ADS)

    Lin, Hai; Yang, Dong; Han, Song; Liu, Yangjie; Yang, Helin

    2016-12-01

    In this paper, we theoretically and experimentally demonstrate a three dimensional metamaterial that can motivate electromagnetic induced transparency (EIT) by using circular polarized wave as stimulations. The unit cell consists of a pair of metallic strips printed on both sides of the printed circuit board (PCB), where a conductive cylinder junction is used to connect the metal strips by drilling a hole inside the substrate. When a right circularly polarized wave is incident, destructive interference is excited between meta-atoms of the 3D structure, the transmission spectrum demonstrates a sharp transparency window. A coupled oscillator model and an electrical equivalent circuit model are applied to quantitatively and qualitatively analyze the coupling mechanism in the EIT-like metamaterial. Analysis in detail shows the EIT window's amplitude and frequency are modulated by changing the degree of symmetry breaking. The proposed metamaterial may achieve potential applications in developing chiral slow light devices.

  15. Effective medium approximation for effective propagation constant calculation in a dense random medium. [electromagnetic wave scattering

    NASA Technical Reports Server (NTRS)

    Zhu, P. Y.; Fung, A. K.

    1986-01-01

    The effective medium approximation (EMA) formalism developed for scalar wave calculations in solid state physics is generalized to electromagnetic wave scattering in a dense random medium. Results are applied to compute the effective propagation constant in a dense medium involving discrete spherical scatterers. When compared with a common quasicrystalline approximation (QCA), it is found that EMA accounts for backward scattering and the effect of correlation among three scatterers which are not available in QCA. It is also found that there is not much difference in the calculated normalized phase velocity between the use of these two approximations. However, there is a significant difference in the computed effective loss tangent in a nonabsorptive random medium. The computed effective loss tangent using EMA and measurements from a snow medium are compared, showing good agreement.

  16. Study of influence of millimeter range electromagnetic waves on water-saline solutions of albumin

    NASA Astrophysics Data System (ADS)

    Shahinyan, Mariam A.; Antonyan, Ara P.; Mikaelyan, Marieta S.; Vardevanyan, Poghos O.

    2015-01-01

    In this work, the effect of electromagnetic waves of millimeter diapason (EMW MM) on both melting parameters of serum albumin from human blood and its solution density has been studied. It was shown that the irradiation of albumin solution results in protein denaturation at higher temperatures than in the case of nonirradiated samples, which indicates the increase of albumin packing degree. It was also shown that the enhancement of albumin solution density takes place which indicates the protein packing degree change as well. The obtained data show that the effect of EMW MM does not depend on frequency of these waves, because alterations are revealed at all studied frequencies — 41.8, 48 and 51.8GHz.

  17. Propagation of electromagnetic waves in stratified media with nonlinearity in both dielectric and magnetic responses.

    PubMed

    Kim, Kihong; Phung, D K; Rotermund, F; Lim, H

    2008-01-21

    We develop a generalized version of the invariant imbedding method, which allows us to solve the electromagnetic wave equations in arbitrarily inhomogeneous stratified media where both the dielectric permittivity and magnetic permeability depend on the strengths of the electric and magnetic fields, in a numerically accurate and efficient manner. We apply our method to a uniform nonlinear slab and find that in the presence of strong external radiation, an initially uniform medium of positive refractive index can spontaneously change into a highly inhomogeneous medium where regions of positive or negative refractive index as well as metallic regions appear. We also study the wave transmission properties of periodic nonlinear media and the influence of nonlinearity on the mode conversion phenomena in inhomogeneous plasmas. We argue that our theory is very useful in the study of the optical properties of a variety of nonlinear media including nonlinear negative index media fabricated using wires and split-ring resonators.

  18. Fokker-Planck electron diffusion caused by an obliquely propagating electromagnetic wave packet of narrow bandwidth

    NASA Technical Reports Server (NTRS)

    Hizanidis, Kyriakos

    1989-01-01

    The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.

  19. High Temperature Shear Horizontal Electromagnetic Acoustic Transducer for Guided Wave Inspection

    PubMed Central

    Kogia, Maria; Gan, Tat-Hean; Balachandran, Wamadeva; Livadas, Makis; Kappatos, Vassilios; Szabo, Istvan; Mohimi, Abbas; Round, Andrew

    2016-01-01

    Guided Wave Testing (GWT) using novel Electromagnetic Acoustic Transducers (EMATs) is proposed for the inspection of large structures operating at high temperatures. To date, high temperature EMATs have been developed only for thickness measurements and they are not suitable for GWT. A pair of water-cooled EMATs capable of exciting and receiving Shear Horizontal (SH0) waves for GWT with optimal high temperature properties (up to 500 °C) has been developed. Thermal and Computational Fluid Dynamic (CFD) simulations of the EMAT design have been performed and experimentally validated. The optimal thermal EMAT design, material selection and operating conditions were calculated. The EMAT was successfully tested regarding its thermal and GWT performance from ambient temperature to 500 °C. PMID:27110792

  20. Potential damage to DC superconducting magnets due to the high frequency electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Gabriel, G. J.

    1977-01-01

    Experimental data are presented in support of the hypothesis that a dc superconducting magnet coil does not behave strictly as an inductor, but as a complicated electrodynamic device capable of supporting electromagnetic waves. Travel times of nanosecond pulses and evidence of sinusoidal standing waves were observed on a prototype four-layer solenoidal coil at room temperature. Ringing observed during switching transients appears as a sequence of multiple reflected square pulses whose durations are related to the layer lengths. With sinusoidal excitation of the coil, the voltage amplitude between a pair of points on the coil exhibits maxima at those frequencies such that the distance between these points is an odd multiple of half wavelength in free space. Evidence indicates that any disturbance, such as that resulting from switching or sudden fault, initiates multiple reflections between layers, thus raising the possibility for sufficiently high voltages to cause breakdown.

  1. Numerical Modeling of High Frequency Electromagnetic Wave Propagation through Ionospheric Plasma with Randomly Distributed Flute Vortices

    NASA Astrophysics Data System (ADS)

    Caplinger, J.; Sotnikov, V. I.; Wallerstein, A. J.

    2014-12-01

    A three dimensional numerical ray-tracing algorithm based on a Hamilton-Jacobi geometric optics approximation is used to analyze propagation of high frequency (HF) electromagnetic waves through a plasma with randomly distributed vortex structures having a spatial dependence in the plane perpendicular to earth's magnetic field. This spatial dependence in density is elongated and uniform along the magnetic field lines. Similar vortex structures may appear in the equatorial spread F region and in the Auroral zone of the ionosphere. The diffusion coefficient associated with wave vector deflection from a propagation path can be approximated by measuring the average deflection angle of the beam of rays. Then, the beam broadening can be described statistically using the Fokker-Planck equation. Visualizations of the ray propagation through generated density structures along with estimated and analytically calculated diffusion coefficients will be presented.

  2. LSP Simulation and Analytical Results on Electromagnetic Wave Scattering on Coherent Density Structures

    NASA Astrophysics Data System (ADS)

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T.

    2014-09-01

    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics (HEDP) and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present PIC simulation results on EM scattering on vortex type density structures using the LSP code and compare them with analytical results. Acknowledgement: This work was supported by the Air Force Research laboratory, the Air Force Office of Scientific Research, the Naval Research Laboratory and NNSA/DOE grant no. DE-FC52-06NA27616 at the University of Nevada at Reno.

  3. Surfatron acceleration of protons by an electromagnetic wave at the heliosphere periphery

    SciTech Connect

    Loznikov, V. M. Erokhin, N. S.; Zol’nikova, N. N.; Mikhailovskaya, L. A.

    2013-10-15

    The trapping and subsequent efficient surfatron acceleration of weakly relativistic protons by an electromagnetic wave propagating across an external magnetic field in plasma at the heliosphere periphery is considered. The problem is reduced to analysis of a second-order time-dependent nonlinear equation for the wave phase on the particle trajectory. The conditions of proton trapping by the wave, the dynamics of the components of the particle momentum and velocity, the structure of the phase plane, the particle trajectories, and the dependence of the acceleration rate on initial parameters of the problem are analyzed. The asymptotic behavior of the characteristics of accelerated particles for the heliosphere parameters is investigated. The optimum conditions for surfatron acceleration of protons by an electromagnetic wave are discussed. It is demonstrated that the experimentally observed deviation of the spectra of cosmic-ray protons from standard power-law dependences can be caused by the surfatron mechanism. It is shown that protons with initial energies of several GeV can be additionally accelerated in the heliosphere (the region located between the shock front of the solar wind and the heliopause at distances of about 100 astronomical units (a.u.) from the Sun) up to energies on the order of several thousands of GeV. In order to explain the proton spectra in the energy range of ∼20–500 GeV, a two-component phenomenological model is proposed. The first component corresponds to the constant (in this energy range) galactic contribution, while the second (variable) component corresponds to the heliospheric contribution, which appears due to the additional acceleration of soft cosmic-ray protons at the heliosphere periphery. Variations in the proton spectra measured on different time scales between 1992 and 2008 in the energy range from several tens to several hundred GeV, as well as the dependence of these spectra on the heliospheric weather, can be explained

  4. Radiation reaction dynamics in an electromagnetic wave and constant electric field

    NASA Astrophysics Data System (ADS)

    Atlee Jackson, E.

    1984-05-01

    The relativistic motion of a charged particle is studied when it is acted on simultaneously by a constant electric field and a plane electromagnetic wave, propagating in the direction of the electric field (x axis). The dynamics includes the radiation reaction (self-force) on the particle through a standard approximation of the Lorentz-Dirac equation. The interest is to determine the result of the competition between the average acceleration due to the electromagnetic wave (``radiation pressure'') and the acceleration due to the constant force of the static field. Each of these actions alone of course produce an unbounded particle energy asymptotically in time. However, it is proved first that, when the ``forces'' are in opposite directions, the particle can never accelerate (on the average) indefinitely in the x direction, regardless how weak the electric field (E0) is compared to the amplitude of the wave (A). It is then proved that all solutions converge to a region of zero area in a suitable velocity phase space and, if there exists a periodic solution [in the phase ξ=ω (t-x/c)] in a specified region of this phase space, then all solutions must converge to this solution asymptotically (ξ→+∞). In the case when (E0A2/ω2) has a specified bound (ω: wave frequency), an iterative method is developed which explicitly yields such a periodic solution, showing that the energy remains bounded. The direction of the average drift is determined in terms of (A,E0,ω). When the parameter (E0A2/ω2) is above this bound, a combination of numerical and analytic results are obtained which indicate that this periodic solution persists. These results indicate that all motions tend to states with bounded energy, regardless of the field strengths.

  5. Electromagnetic wave attenuation measurements in a ring-shaped inductively coupled air plasma

    SciTech Connect

    Xiaolong, Wei; Haojun, Xu; Min, Lin; Chen, Su; Jianhai, Li

    2015-05-28

    An aerocraft with the surface, inlet and radome covered large-area inductive coupled plasma (ICP) can attenuate its radar echo effectively. The shape, thickness, and electron density (N{sub e}) distribution of ICP are critical to electromagnetic wave attenuation. In the paper, an air all-quartz ICP generator in size of 20 × 20 × 7 cm{sup 3} without magnetic confinement is designed. The discharge results show that the ICP is amorphous in E-mode and ring-shaped in H-mode. The structure of ICP stratifies into core region and edge halo in H-mode, and its width and thickness changes from power and pressure. Such phenomena are explained by the distribution of RF magnetic field, the diffusion of negative ions plasma and the variation of skin depth. In addition, the theoretical analysis shows that the N{sub e} achieves nearly uniform within the electronegative core and sharply steepens in the edge. The N{sub e} of core region is diagnosed by microwave interferometer under varied conditions (pressure in range of 10–50 Pa, power in 300–700 W). Furthermore, the electromagnetic wave attenuation measurements were carried out with the air ICP in the frequencies of 4–5 GHz. The results show that the interspaced ICP is still effective to wave attenuation, and the wave attenuation increases with the power and pressure. The measured attenuation is approximately in accordance with the calculation data of finite-different time-domain simulations.

  6. Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure

    NASA Astrophysics Data System (ADS)

    Cho, J.-H.; Lee, D.-Y.; Noh, S.-J.; Shin, D.-K.; Hwang, J.; Kim, K.-C.; Lee, J. J.; Choi, C. R.; Thaller, S.; Skoug, R.

    2016-10-01

    Magnetospheric compression due to impact of enhanced solar wind dynamic pressure Pdyn has long been considered as one of the generation mechanisms of electromagnetic ion cyclotron (EMIC) waves. With the Van Allen Probe-A observations, we identify three EMIC wave events that are triggered by Pdyn enhancements under prolonged northward interplanetary magnetic field (IMF) quiet time preconditions. They are in contrast to one another in a few aspects. Event 1 occurs in the middle of continuously increasing Pdyn while Van Allen Probe-A is located outside the plasmapause at postmidnight and near the equator (magnetic latitude (MLAT) -3°). Event 2 occurs by a sharp Pdyn pulse impact while Van Allen Probe-A is located inside the plasmapause in the dawn sector and rather away from the equator (MLAT 12°). Event 3 is characterized by amplification of a preexisting EMIC wave by a sharp Pdyn pulse impact while Van Allen Probe-A is located outside the plasmapause at noon and rather away from the equator (MLAT -15°). These three events represent various situations where EMIC waves can be triggered by Pdyn increases. Several common features are also found among the three events. (i) The strongest wave is found just above the He+ gyrofrequency. (ii) The waves are nearly linearly polarized with a rather oblique propagation direction ( 28° to 39° on average). (iii) The proton fluxes increase in immediate response to the Pdyn impact, most significantly in tens of keV energy, corresponding to the proton resonant energy. (iv) The temperature anisotropy with T⊥ > T|| is seen in the resonant energy for all the events, although its increase by the Pdyn impact is not necessarily always significant. The last two points (iii) and (iv) may imply that in addition to the temperature anisotropy, the increase of the resonant protons must have played a critical role in triggering the EMIC waves by the enhanced Pdyn impact.

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

    PubMed

    Tang, Zhanghong; Wang, Qun; Ji, Zhijiang; Shi, Meiwu; Hou, Guoyan; Tan, Danjun; Wang, Pengqi; Qiu, Xianbo

    2014-12-01

    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.

  8. Flexible and Thermostable Graphene/SiC Nanowire Foam Composites with Tunable Electromagnetic Wave Absorption Properties.

    PubMed

    Han, Meikang; Yin, Xiaowei; Hou, Zexin; Song, Changqing; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2017-04-05

    Three-dimensional (3D) flexible foams consisting of reduced graphene oxides (rGO) and in situ grown SiC nanowires (NWs) were prepared using freeze-drying and carbothermal reduction processes. By means of incorporating SiC nanowires into rGO foams, both the thermostability and electromagnetic absorption of the composites were improved. It was demonstrated that rGO/SiC NW foams were thermostable beyond ∼630 °C (90% weight retention in air atmosphere). As expected, rGO/SiC NW foams in the poly(dimethylsiloxane) matrix achieved effective absorption in the entire X-band (8.2-12.4 GHz) with a thinner thickness (3 mm) in comparison with those of the pure rGO foams. It is revealed that SiC nanowires with abundant stacking faults, twinning interfaces, and bridged junctions play an important role in the enhanced electromagnetic absorption performance, in addition to the contribution of interconnected graphene networks. Hierarchical rGO/SiC NW foams not only are efficient absorbers in the critical environments but also can be applied in photocatalytic and thermal-management fields.

  9. Numerical absorbing boundary conditions based on a damped wave equation for pseudospectral time-domain acoustic simulations.

    PubMed

    Spa, Carlos; Reche-López, Pedro; Hernández, Erwin

    2014-01-01

    In the context of wave-like phenomena, Fourier pseudospectral time-domain (PSTD) algorithms are some of the most efficient time-domain numerical methods for engineering applications. One important drawback of these methods is the so-called Gibbs phenomenon. This error can be avoided by using absorbing boundary conditions (ABC) at the end of the simulations. However, there is an important lack of ABC using a PSTD methods on a wave equation. In this paper, we present an ABC model based on a PSTD damped wave equation with an absorption parameter that depends on the position. Some examples of optimum variation profiles are studied analytically and numerically. Finally, the results of this model are also compared to another ABC model based on an hybrid formulation of the scalar perfectly matched layer.

  10. Random walk of electrons in a gas in the presence of polarized electromagnetic waves: Genesis of a wave induced discharge

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Sudeep; Paul, Samit

    2009-10-01

    The average number of collisions N of seed electrons with neutral gas atoms during random walk in escaping from a given volume, in the presence of polarized electromagnetic waves, is found to vary as N =B(Λ /λ)2/[1+C(Λ /λ)]2, indicating a modification to the conventional field free square law N =A(Λ /λ)2, where Λ is the characteristic diffusion length and λ the mean free path. It is found that for the field free case A =1.5 if all the electrons originate at the center and is 1.25 if they are allowed to originate at any random point in the given volume. The B and C coefficients depend on the wave electric field and frequency. Predictions of true discharge initiation time τc can be made from the temporal evolution of seed electrons over a wide range of collision frequencies. For linearly polarized waves of 2.45 GHz and electric field in the range (0.6-1.0)×105 V/m, τc=5.5-1.6 ns for an unmagnetized microwave driven discharge at 1 Torr argon.

  11. Nonlinear dispersion and transverse profile of intense electromagnetic waves, propagating through electron-positron-ion hot magnetoplasma

    SciTech Connect

    Javan, N. Sepehri Homami, S. H. H.

    2015-02-15

    Self-guided nonlinear propagation of intense circularly-polarized electromagnetic waves in a hot electron-positron-ion magnetoplasma is studied. Using a relativistic fluid model, a nonlinear equation is derived, which describes the interaction of the electromagnetic wave with the plasma in the quasi-neutral approximation. Transverse Eigen modes, the nonlinear dispersion relation and the group velocity are obtained. Results show that the transverse profile in the case of magnetized plasma with cylindrical symmetry has a radially damping oscillatory form. Effect of applying external magnetic fields, existence of the electron-positron pairs, changing the amplitude of the electromagnetic wave, and its polarization on the nonlinear dispersion relation and Eigen modes are studied.

  12. Investigation on broadband propagation characteristic of terahertz electromagnetic wave in anisotropic magnetized plasma in frequency and time domain

    SciTech Connect

    Tian, Yuan; Han, Yiping; Ai, Xia; Liu, Xiuxiang

    2014-12-15

    In this paper, we investigate the propagation of terahertz (THz) electromagnetic wave in an anisotropic magnetized plasma by JE convolution-finite difference time domain method. The anisotropic characteristic of the plasma, which leads to right-hand circularly polarized (RCP) and right-hand circularly polarized (LCP) waves, has been taken into account. The interaction between electromagnetic waves and magnetized plasma is illustrated by reflection and transmission coefficients for both RCP and LCP THz waves. The effects of both the magnetized plasma thickness and the external magnetized field are analyzed and numerical results demonstrate that the two factors could influence the THz wave greatly. It is worthy to note that besides the reflection and transmission coefficients in the frequency domain, the waveform of the electric field in the time domain varying with thicknesses and external magnetic fields for different polarized direction has been studied.

  13. Radiation of de-excited electrons at large times in a strong electromagnetic plane wave

    SciTech Connect

    Kazinski, P.O.

    2013-12-15

    The late time asymptotics of the physical solutions to the Lorentz–Dirac equation in the electromagnetic external fields of simple configurations–the constant homogeneous field, the linearly polarized plane wave (in particular, the constant uniform crossed field), and the circularly polarized plane wave–are found. The solutions to the Landau–Lifshitz equation for the external electromagnetic fields admitting a two-parametric symmetry group, which include as a particular case the above mentioned field configurations, are obtained. Some general properties of the total radiation power of a charged particle are established. In particular, for a circularly polarized wave and constant uniform crossed fields, the total radiation power in the asymptotic regime is independent of the charge and the external field strength, when expressed in terms of the proper-time, and equals a half the rest energy of a charged particle divided by its proper-time. The spectral densities of the radiation power formed on the late time asymptotics are derived for a charged particle moving in the external electromagnetic fields of the simple configurations pointed above. This provides a simple method to verify experimentally that the charged particle has reached the asymptotic regime. -- Highlights: •Late time asymptotics of the solutions to the Lorentz–Dirac equation are studied. •General properties of the total radiation power of electrons are established. •The total radiation power equals a half the rest energy divided by the proper-time. •Spectral densities of radiation formed on the late time asymptotics are derived. •Possible experimental verification of the results is proposed.

  14. Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    SciTech Connect

    Guzatov, D V; Gaida, L S; Afanas'ev, Anatolii A

    2008-12-31

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves. (light pressure)

  15. Monitoring in situ retorting processes of oil shale by reflected and transmitted electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Hong, S. H.; DuBow, J. B.

    1980-07-01

    A theoretical model for an in situ oil shale retort with three distinct vertical zones, all surrounded by a wall of oil shale, overburden and underburden, is considered for the study of potential electromagnetic monitoring of the progression of retorting processes using wave propagation techniques. The overall power reflection and transmission coefficients for both transverse electric and transverse magnetic waves are used for finding the position of a combustion zone in the retort, based upon the assumption of straight-line propagation of monochromatic plane waves through layered lossy dielectric media characterized by the dielectric constants and loss tangents. The behavior of each power coefficient is discussed as a function of burn front positions and signal frequencies. As a result of the relatively moderate signal power for each coefficient required for detection, and the one-to-one correspondence between each power coefficient and burn front position at typical conditions, the feasibility of using low radio-frequency waves to monitor relatively large scale in situ retorting process is established.

  16. Self-focusing of electromagnetic surface waves on a nonlinear impedance surface

    SciTech Connect

    Luo, Zhangjie; Chen, Xing; Long, Jiang; Quarfoth, Ryan; Sievenpiper, Daniel

    2015-05-25

    The self-focusing effect of optical beams has been a popular topic of study for quite a while, but such a nonlinear phenomenon at microwave frequencies has never been realized, partially due to the underdevelopment of nonlinear material. In this research, self-focused electromagnetic (EM) surface waves are demonstrated on a circuit-based, power-dependent impedance surface. The formation of a self-focused beam is investigated using a series of discrete-time simulations, and the result is further validated in measurement. It is experimentally observed that, in contrast to the normal scattering of low-power surface waves, high-power waves propagate through the surface while maintaining narrow beam width, and even converge extremely tightly to create a hot spot with higher power. The result is essentially a nonlinear effect of the surface that compensates for the natural tendency of surface waves to diffract. This intriguing experiment can be extended to various potential EM applications such as power-dependent beam steering antennas and nonlinear microwave propagation or dissipation.

  17. Latitudinal dependence of nonlinear interaction between electromagnetic ion cyclotron wave and terrestrial ring current ions

    SciTech Connect

    Su, Zhenpeng Zhu, Hui; Zheng, Huinan; Xiao, Fuliang; Zhang, Min; Liu, Y. C.-M.; Shen, Chao; Wang, Yuming; Wang, Shui

    2014-05-15

    Electromagnetic ion cyclotron (EMIC) waves can lead to the rapid decay (on a timescale of hours) of the terrestrial ring current. Such decay process is usually investigated in the framework of quasi-linear theory. Here, both theoretical analysis and test-particle simulation are performed to understand the nonlinear interaction between ring current ions and EMIC waves. In particular, the dependence of the nonlinear wave-particle interaction processes on the ion initial latitude is investigated in detail. These nonlinear processes are classified into the phase trapping and phase bunching, and the phase bunching is further divided into the channel and cluster effects. Compared to the prediction of the quasi-linear theory, the ring current decay rate can be reduced by the phase trapping, increased by the channel effect phase bunching, but non-deterministically influenced by the cluster effect phase bunching. The ion initial latitude changes the occurrence of the phase trapping, modulates the transport direction and strength of the cluster effect phase bunching, and only slightly affects the channel effect phase bunching. The current results suggest that the latitudinal dependence of these nonlinear processes should be considered in the evaluation of the ring current decay induced by EMIC waves.

  18. Pipe wall damage detection by electromagnetic acoustic transducer generated guided waves in absence of defect signals.

    PubMed

    Vasiljevic, Milos; Kundu, Tribikram; Grill, Wolfgang; Twerdowski, Evgeny

    2008-05-01

    Most investigators emphasize the importance of detecting the reflected signal from the defect to determine if the pipe wall has any damage and to predict the damage location. However, often the small signal from the defect is hidden behind the other arriving wave modes and signal noise. To overcome the difficulties associated with the identification of the small defect signal in the time history plots, in this paper the time history is analyzed well after the arrival of the first defect signal, and after different wave modes have propagated multiple times through the pipe. It is shown that the defective pipe can be clearly identified by analyzing these late arriving diffuse ultrasonic signals. Multiple reflections and scattering of the propagating wave modes by the defect and pipe ends do not hamper the defect detection capability; on the contrary, it apparently stabilizes the signal and makes it easier to distinguish the defective pipe from the defect-free pipe. This paper also highlights difficulties associated with the interpretation of the recorded time histories due to mode conversion by the defect. The design of electro-magnetic acoustic transducers used to generate and receive the guided waves in the pipe is briefly described in the paper.

  19. Oblique electromagnetic electron cyclotron waves for Kappa distribution with AC field in planetary magnetospheres

    NASA Astrophysics Data System (ADS)

    Pandey, R. S.; Kaur, Rajbir

    2015-08-01

    The dispersion relation for obliquely propagating relativistic electromagnetic electron cyclotron (EMEC) waves in collision-less magnetoplasma is obtained. Investigations for EMEC waves in magnetosphere of Jupiter, Saturn and Uranus have been done, in presence of perpendicular AC electric field for Kappa distribution function. The relativistic temporal growth rate is calculated using method of characteristic solution. Using the data provided by spacecrafts like Cassini, Voyager 1 and 2, while exploring the magnetosphere of Jupiter, Saturn and Uranus, is used to plot graphs showing growth rate being effected by various parameters. Comprehensive parametric analysis have been done at different radial distances of the planets. It is concluded that beside huge difference in magnetospheric configuration, temperature anisotropy remains the main source of energy in case of Jupiter and Uranus. While studying EMEC waves in magnetosphere of Saturn, it is inferred that growth rate attains maximum magnitude when angle of propagation increases. Also, the results and its interpretations explain how the growth of EMEC wave modifies in different magnetospheric conditions.

  20. Nonlinear evolution of the plasma beat wave: Compressing the laser beat notes via electromagnetic cascading

    SciTech Connect

    Kalmykov, Serguei; Shvets, Gennady

    2006-04-15

    The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron plasma frequency, the redshifted spectral components are advanced in time with respect to the blueshifted ones near the center of each laser beat note. The group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bistability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially subthreshold beat wave pulse.

  1. Nonlinear evolution of the plasma beat wave: Compressing the laser beat notes via electromagnetic cascading

    NASA Astrophysics Data System (ADS)

    Kalmykov, Serguei; Shvets, Gennady

    2006-04-01

    The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron plasma frequency, the redshifted spectral components are advanced in time with respect to the blueshifted ones near the center of each laser beat note. The group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bistability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially subthreshold beat wave pulse.

  2. Nonlinear evolution of the plasma beat wave: Compressing the laser beat notes via electromagnetic cascading.

    PubMed

    Kalmykov, Serguei; Shvets, Gennady

    2006-04-01

    The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron plasma frequency, the redshifted spectral components are advanced in time with respect to the blueshifted ones near the center of each laser beat note. The group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bistability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially subthreshold beat wave pulse.

  3. Freja observations of electromagnetic ion cyclotron ELF waves and transverse oxygen ion acceleration on auroral field lines

    SciTech Connect

    Erlandson, R.E.; Zanetti, L.J.; Acuna, M.H.; Eliasson, L.; Boehm, M.H.; Blomberg, L.G.

    1994-08-15

    Extremely low-frequency (ELF) magnetic and electric field plasma wave emissions were recorded on 2 October 1993 on auroral field lines by the Magnetic Field Experiment during Freja orbit 4770. The ELF wave frequencies were below the local oxygen gyrofrequency (25 Hz) and between the helium and proton gyrofrequencies (100 to 400 Hz). The ELF waves, interpreted as electromagnetic ion cyclotron (EMIC) waves, were observed in a region of inverted-V-type electron precipitation. The EMIC waves were correlated over time with auroral and lower energy ({approximately} 100 eV) electrons, which are both possible sources of free energy, and also with transversely accelerated oxygen ions. The waves above the helium gyrofrequency were more closely correlated with the transverse oxygen ion acceleration than the waves below the oxygen gyrofrequency. These observations are consistent with a scenario in which electron beams generate EMIC waves, which then produce transverse oxygen ion acceleration through a gyroresonant interaction. 16 refs., 4 figs.

  4. Electromagnetic particle simulation of the effect of toroidicity on linear mode conversion and absorption of lower hybrid waves

    NASA Astrophysics Data System (ADS)

    Bao, J.; Lin, Z.; Kuley, A.; Wang, Z. X.

    2016-06-01

    Effects of toroidicity on linear mode conversion and absorption of lower hybrid (LH) waves in fusion plasmas have been studied using electromagnetic particle simulation. The simulation confirms that the toroidicity induces an upshift of parallel refractive index when LH waves propagate from the tokamak edge toward the core, which affects the radial position for the mode conversion between slow and fast LH waves. Furthermore, moving LH antenna launch position from low field side toward high field side leads to a larger upshift of the parallel refractive index, which helps the slow LH wave penetration into the tokamak core. The broadening of the poloidal spectrum of the wave-packet due to wave diffraction is also verified in the simulation. Both the upshift and broadening effects of the parallel spectrum of the wave-packet modify the parallel phase velocity and thus the linear absorption of LH waves by electron Landau resonance.

  5. Energy and angular momentum transfers from an electromagnetic wave to a copper ring in the UHF band

    NASA Astrophysics Data System (ADS)

    Émile, Olivier; Brousseau, Christian; Émile, Janine; Mahdjoubi, Kouroch

    2017-02-01

    Electromagnetic waves could carry orbital angular momentum. Such momentum can be transferred to macroscopic objects and can make them rotate under a constant torque. Based on experimental observations, we investigate the origin of orbital angular momentum and energy transfer. Due to angular momentum and energy conservation, we show that angular momentum transfer is due to the change in the sign of angular momentum upon reflection. This leads to a rotational Doppler shift of the electromagnetic wave frequency, ensuring energy conservation. xml:lang="fr"

  6. Correlation between intensity fluctuations induced by scattering of a partially coherent, electromagnetic wave from a quasi-homogeneous medium

    NASA Astrophysics Data System (ADS)

    Li, Jia; Chang, Liping; Chen, Feinan

    2016-12-01

    Based on the first-order Born approximation, the correlation between intensity fluctuations is derived for a partially coherent, electromagnetic plane wave scattering from a spatially quasi-homogeneous medium. Young's pinholes are utilized to control the degree of coherence of the incident field. For the electromagnetic scattering case, it is shown that the CIF of the scattered field strongly depends on the degree of polarization of the incident wave, Young's pinhole parameter, effective radius and correlation length of the medium. The influences of these parameters on the CIF distributions are revealed by numerical calculations.

  7. Mushroom plasmonic metamaterial infrared absorbers

    SciTech Connect

    Ogawa, Shinpei Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  8. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  9. Radiation of terahertz electromagnetic waves from build-in nano Josephson junctions of cuprate high-T(c) superconductors.

    PubMed

    Lin, Shi-Zeng; Hu, Xiao

    2011-04-01

    The nano-scale intrinsic Josephson junctions in highly anisotropic cuprate superconductors have potential for generation of terahertz electromagnetic waves. When the thickness of a superconductor sample is much smaller than the wavelength of electromagnetic waves in vacuum, the superconductor renders itself as a cavity. Unlike conventional lasers, the presence of the cavity does not guarantee a coherent emission because of the internal degree of freedom of the superconductivity phase in long junctions. We study the excitation of terahertz wave by solitons in a stack of intrinsic Josephson junctions, especially for relatively short junctions. Coherent emission requires a rectangular configuration of solitons. However such a configuration is unstable against weak fluctuations, contrarily solitons favor a triangular lattice corresponding to an out-phase oscillation of electromagnetic waves. To utilize the cavity, we propose to use an array of stacks of short intrinsic Josephson junctions to generate powerful terahertz electromagnetic waves. The cavity synchronizes the plasma oscillation in different stacks and the emission intensity is predicted to be proportional to the number of stacks squared.

  10. Electromagnetic fields backscattered from an s-shaped inlet cavity with an absorber coating on its inner walls

    NASA Technical Reports Server (NTRS)

    Burkholder, R. J.; Chuang, C. W.; Pathak, P. H.

    1987-01-01

    The EM backscatter from a two-dimensional S-shaped inlet cavity is analyzed using three different techniques, namely a hybrid combination of asymptotic high frequency and modal methods, an integral equation method, and the geometrical optics ray method, respectively. This inlet has a thin absorber coating on its perfectly conducting inner walls and the planar interior termination is made perfectly conducting. The effect of the absorber on the inner wall is treated via a perturbation scheme in the hybrid approach where it is assumed that the loss is sufficiently small for the method to be valid. The results are compared with the backscatter from a straight inlet cavity to evaluate the effect of offsetting the termination in the S-bend configuration such that it is not visible from the open end of the inlet. The envelope of the backscatter pattern for the straight inlet is always seen to peak around the forward axis due to the large return from the directly visible termination, and the pattern envelope tapers off away from the forward axis. Offsetting the termination causes the envelope of the backscatter pattern to flatten out, thereby reducing the return near the forward axis by several dB. The absorber coating reduces the pattern level of the straight inlet in directions away from the forward axis but has little effect on the peak near the axis; furthermore, the absorber coating is seen to consistently reduce the backscatter from the S-bend inlet for almost all incidence angles. The hybrid method gives excellent agreement with experimental data and with the integral equation solution, whereas, the geometrical optics ray tracing method is able to generally predict the average of the bachscatter pattern but not the pattern details.

  11. Electromagnetic particle simulation of the effect of toroidicity on linear mode conversion and absorption of lower hybrid waves

    NASA Astrophysics Data System (ADS)

    Bao, Jian; Lin, Zhihong; Kuley, Animesh; Wang, Zhixuan

    2016-10-01

    Effects of toroidicity on linear mode conversion and absorption of lower hybrid (LH) waves in tokamak have been studied by electromagnetic particle simulation using GTC. The simulation confirms that the toroidicity induces an upshift of parallel refractive index when LH waves propagate from the tokamak edge toward the core, which affects the radial position for the mode conversion between slow and fast LH waves. Furthermore, moving LH antenna launch position from low field side toward high field side leads to a larger upshift of the parallel refractive index, which helps the slow LH wave penetration into the tokamak core. The broadening of the poloidal spectrum of the wave-packet due to wave diffraction is also verified in the simulation. Both the upshift and broadening effects of the parallel spectrum of the wave-packet modify the parallel phase velocity and thus the linear absorption of LH waves by electron Landau resonance. In the nonlinear electromagnetic simulation, nonlinear wave trapping of electrons is verified and a plasma current is nonlinearly driven. Preliminary results of the nonlinear parametric decay of LH waves will be presented.

  12. Intracavity absorption with a continuous wave dye laser - Quantification for a narrowband absorber

    NASA Technical Reports Server (NTRS)

    Brobst, William D.; Allen, John E., Jr.

    1987-01-01

    An experimental investigation of the dependence of intracavity absorption on factors including transition strength, concentration, absorber path length, and pump power is presented for a CW dye laser with a narrow-band absorber (NO2). A Beer-Lambert type relationship is found over a small but useful range of these parameters. Quantitative measurement of intracavity absorption from the dye laser spectral profiles showed enhancements up to 12,000 (for pump powers near lasing threshold) when compared to extracavity measurements. The definition of an intracavity absorption coefficient allowed the determination of accurate transition strength ratios, demonstrating the reliability of the method.

  13. Influence of electromagnetic oscillating two-stream instability on the evolution of laser-driven plasma beat-wave

    SciTech Connect

    Gupta, D. N.; Singh, K. P.; Suk, H.

    2007-01-15

    The electrostatic oscillating two-stream instability of laser-driven plasma beat-wave was studied recently by Gupta et al. [Phys. Plasmas 11, 5250 (2004)], who applied their theory to limit the amplitude level of a plasma wave in the beat-wave accelerator. As a self-generated magnetic field is observed in laser-produced plasma, hence, the electromagnetic oscillating two-stream instability may be another possible mechanism for the saturation of laser-driven plasma beat-wave. The efficiency of this scheme is higher than the former.

  14. Temperature measurements behind reflected shock waves in air. [radiometric measurement of gas temperature in self-absorbing gas flow

    NASA Technical Reports Server (NTRS)

    Bader, J. B.; Nerem, R. M.; Dann, J. B.; Culp, M. A.

    1972-01-01

    A radiometric method for the measurement of gas temperature in self-absorbing gases has been applied in the study of shock tube generated flows. This method involves making two absolute intensity measurements at identical wavelengths, but for two different pathlengths in the same gas sample. Experimental results are presented for reflected shock waves in air at conditions corresponding to incident shock velocities from 7 to 10 km/s and an initial driven tube pressure of 1 torr. These results indicate that, with this technique, temperature measurements with an accuracy of + or - 5 percent can be carried out. The results also suggest certain facility related problems.

  15. Rapid determination of carboxyhemoglobin by absorbance difference between double wave length.

    PubMed

    Sakata, M; Haga, M

    1980-05-01

    A spectrophotometric determination of CO-Hb content was investigated on the basis of double wavelength spectrophotometry. Absorbance differences at the two wavelengths at which O2-Hb has the same absorbance reflect only the CO-Hb component because the O2-Hb component is nulled out from the mixture of O2-Hb and CO-Hb. After measurement of absorbance difference, the measuring solution was saturated with pure CO and remeasured. CO-Hb % was calculated from the ratio of the absorbance differences. Since temperature significantly influences the spectrum of hemoglobin pigment, the wavelength pair changed with temperature. For accurate measurement, it was necessary to control temperature of diluting solution before dilution. Liberation of CO fro CO-Hb was observed at more than 80% CO-Hb, and 5% and 2% liberation from 100% CO-Hb occured at 100-fold dilution with 10 mm cuvette and 20-fold dilution with 2 mm cuvette respectively. Advantages of this method are that the standard curve or equation for calculation and accurate dilution are not necessary because the interfering component is nulled out and 100% CO-Hb of the standard sample is made with the same sample; and measurement is very rapid, taking less than 2 min.

  16. Electromagnetic and microwave absorbing properties of SmCo coated single-wall carbon nanotubes/NiZn-ferrite nanocrystalline composite

    NASA Astrophysics Data System (ADS)

    Duan, M. C.; Yu, L. M.; Sheng, L. M.; An, K.; Ren, W.; Zhao, X. L.

    2014-05-01

    The electromagnetism and microwave absorption properties of SmCo coated single-wall carbon nanotubes (SmCo@SWCNTs) and Ni0.5Zn0.5Fe2O4 ferrite (NiZn-ferrite) nanocrystalline composites with different ingredient weight ratios were investigated in the frequency range of 2-18 GHz. SmCo@SWCNTs were prepared by a direct current arc discharge method. NiZn-ferrite nanocrystalline was synthesized by a sol-gel method. The electromagnetic properties of the nanocomposites in the paraffin matrix were measured by a vector network analyzer. The Debye equation and Bruggeman symmetric medium equation were introduced to explain the dielectric properties of the nanocomposites, and the mechanisms for the dielectric and magnetic losses were discussed. The experiment results reveal that the absorbing properties of the nanocomposites could be improved by tuning for a suitable weight ratio between SmCo@SWCNTs and NiZn-ferrite nanocrystallines. The reflection loss simulation calculations demonstrated that the nanocomposite could be excellent materials for microwave absorption.

  17. Apparatus and method for enhanced chemical processing in high pressure and atmospheric plasmas produced by high frequency electromagnetic waves

    DOEpatents

    Efthimion, Philip C.; Helfritch, Dennis J.

    1989-11-28

    An apparatus and method for creating high temperature plasmas for enhanced chemical processing of gaseous fluids, toxic chemicals, and the like, at a wide range of pressures, especially at atmospheric and high pressures includes an electro-magnetic resonator cavity, preferably a reentrant cavity, and a wave guiding structure which connects an electro-magnetic source to the cavity. The cavity includes an intake port and an exhaust port, each having apertures in the conductive walls of the cavity sufficient for the intake of the gaseous fluids and for the discharge of the processed gaseous fluids. The apertures are sufficiently small to prevent the leakage of the electro-magnetic radiation from the cavity. Gaseous fluid flowing from the direction of the electro-magnetic source through the guiding wave structure and into the cavity acts on the plasma to push it away from the guiding wave structure and the electro-magnetic source. The gaseous fluid flow confines the high temperature plasma inside the cavity and allows complete chemical processing of the gaseous fluids at a wide range of pressures.

  18. Experimentally validated multiphysics computational model of focusing and shock wave formation in an electromagnetic lithotripter

    PubMed Central

    Fovargue, Daniel E.; Mitran, Sorin; Smith, Nathan B.; Sankin, Georgy N.; Simmons, Walter N.; Zhong, Pei

    2013-01-01

    A multiphysics computational model of the focusing of an acoustic pulse and subsequent shock wave formation that occurs during extracorporeal shock wave lithotripsy is presented. In the electromagnetic lithotripter modeled in this work the focusing is achieved via a polystyrene acoustic lens. The transition of the acoustic pulse through the solid lens is modeled by the linear elasticity equations and the subsequent shock wave formation in water is modeled by the Euler equations with a Tait equation of state. Both sets of equations are solved simultaneously in subsets of a single computational domain within the BEARCLAW framework which uses a finite-volume Riemann solver approach. This model is first validated against experimental measurements with a standard (or original) lens design. The model is then used to successfully predict the effects of a lens modification in the form of an annular ring cut. A second model which includes a kidney stone simulant in the domain is also presented. Within the stone the linear elasticity equations incorporate a simple damage model. PMID:23927200

  19. Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion, pure reflections, and bulk polaritons

    SciTech Connect

    Alshits, V. I. Lyubimov, V. N.; Radowicz, A.

    2007-02-15

    A theory is constructed for the reflection of plane electromagnetic waves in uniaxial crystals with a positive definite permittivity tensor and an arbitrarily oriented metallized boundary. The problem is solved both for general-position orientations corresponding to three-partial reflection and for special conditions allowing two-partial reflections: mode conversions when the incident and reflected waves belong to different sheets of the refraction surface and 'pure' reflections when both waves belong to the same sheet. The space of pure reflections is shown to be formed by two types of optical-axis orientations: arbitrary directions in the plane of the crystal surface and in the plane of incidence. The configurations of the conversion surface for optically positive and negative crystals are investigated. A subspace of pure reflections that transform into one-partial bulk polaritons with the energy flux parallel to the surface at grazing incidence has been found. The domain of existence of such bulk eigenmodes is bounded by two 'lines' of solutions. These are any directions along the boundary containing the optical axis for ordinary polaritons and the direction along the projection of the optical axis onto the surface at an arbitrary orientation of the axis with respect to the boundary for extraordinary polaritons.

  20. Experimentally validated multiphysics computational model of focusing and shock wave formation in an electromagnetic lithotripter.

    PubMed

    Fovargue, Daniel E; Mitran, Sorin; Smith, Nathan B; Sankin, Georgy N; Simmons, Walter N; Zhong, Pei

    2013-08-01

    A multiphysics computational model of the focusing of an acoustic pulse and subsequent shock wave formation that occurs during extracorporeal shock wave lithotripsy is presented. In the electromagnetic lithotripter modeled in this work the focusing is achieved via a polystyrene acoustic lens. The transition of the acoustic pulse through the solid lens is modeled by the linear elasticity equations and the subsequent shock wave formation in water is modeled by the Euler equations with a Tait equation of state. Both sets of equations are solved simultaneously in subsets of a single computational domain within the BEARCLAW framework which uses a finite-volume Riemann solver approach. This model is first validated against experimental measurements with a standard (or original) lens design. The model is then used to successfully predict the effects of a lens modification in the form of an annular ring cut. A second model which includes a kidney stone simulant in the domain is also presented. Within the stone the linear elasticity equations incorporate a simple damage model.