Effect of ion-neutral collisions on the evolution of kinetic Alfvén waves in plasmas

NASA Astrophysics Data System (ADS)

Goyal, R.; Sharma, R. P.

2018-03-01

This paper studies the effect of ion-neutral collisions on the propagation of kinetic Alfvén waves (KAWs) in inhomogeneous magnetized plasma. The inhomogeneity in the plasma imposed by background density in a direction transverse as well as parallel to the ambient magnetic field plays a vital role in the localization process. The mass loading of ions takes place due to their collisions with neutral fluid leading to the damping of the KAWs. Numerical analysis of linear KAWs in inhomogeneous magnetized plasma is done for a fixed finite frequency taking into consideration the ion-neutral collisions. There is a prominent effect of collisional damping on the wave localization, wave magnetic field, and frequency spectrum. A semi-analytical technique has been employed to study the magnetic field amplitude decay process and the effect of wave frequency in the range of ion cyclotron frequency on the propagation of waves leading to damping.

Wave propagation in strongly dispersive superthermal dusty plasma

NASA Astrophysics Data System (ADS)

El-Labany, S. K.; El-Shewy, E. K.; Abd El-Razek, H. N.; El-Rahman, A. A.

2017-04-01

The attributes of acoustic envelope waves in a collisionless dust ion unmagnetized plasmas model composed of cold ions, superthermal electrons and positive-negative dust grains have been studied. Using the derivative expansion technique in a strong dispersive medium, the system model is reduced to a nonlinearly form of Schrodinger equation (NLSE). Rational solution of NLSE in unstable region is responsible for the creation of large shape waves; namely rogue waves. The subjection of instability regions upon electron superthermality (via κ), carrier wave number and dusty grains charge is discussed.

Linear Transformation of Electromagnetic Wave Beams of the Electron-Cyclotron Range in Toroidal Magnetic Configurations

NASA Astrophysics Data System (ADS)

Khusainov, T. A.; Shalashov, A. G.; Gospodchikov, E. D.

2018-05-01

The field structure of quasi-optical wave beams tunneled through the evanescence region in the vicinity of the plasma cutoff in a nonuniform magnetoactive plasma is analyzed. This problem is traditionally associated with the process of linear transformation of ordinary and extraordinary waves. An approximate analytical solution is constructed for a rather general magnetic configuration applicable to spherical tokamaks, optimized stellarators, and other magnetic confinement systems with a constant plasma density on magnetic surfaces. A general technique for calculating the transformation coefficient of a finite-aperture wave beam is proposed, and the physical conditions required for the most efficient transformation are analyzed.

Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

NASA Astrophysics Data System (ADS)

Kim, Yong W.

Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

Time resolved interferometric study of the plasma plume induced shock wave in confined geometry: Two-dimensional mapping of the ambient and plasma density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, Kaushik; Singh, R. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in

2016-04-15

An experimental investigation of the laser produced plasma induced shock wave in the presence of confining walls placed along the axial as well as the lateral direction has been performed. A time resolved Mach Zehnder interferometer is set up to track the primary as well as the reflected shock waves and its effect on the evolving plasma plume has been studied. An attempt has been made to discriminate the electronic and medium density contributions towards the changes in the refractive index of the medium. Two dimensional spatial distributions for both ambient medium density and plasma density (electron density) have beenmore » obtained by employing customised inversion technique and algorithm on the recorded interferograms. The observed density pattern of the surrounding medium in the presence of confining walls is correlated with the reflected shock wave propagation in the medium. Further, the shock wave plasma interaction and the subsequent changes in the shape and density of the plasma plume in confined geometry are briefly described.« less

Optical shaping of gas targets for laser–plasma ion sources

DOE PAGES

Dover, N. P.; Cook, N.; Tresca, O.; ...

2016-02-09

In this paper, we report on the experimental demonstration of a technique to generate steep density gradients in gas-jet targets of interest to laser–plasma ion acceleration. By using an intentional low-energy prepulse, we generated a hydrodynamic blast wave in the gas to shape the target prior to the arrival of an intense COmore » $$_{2}$$($${\\it\\lambda}\\approx 10~{\\rm\\mu}\\text{m}$$) drive pulse. This technique has been recently shown to facilitate the generation of ion beams by shockwave acceleration (Trescaet al.,Phys. Rev. Lett., vol. 115 (9), 2015, 094802). Here, we discuss and introduce a model to understand the generation of these blast waves and discuss in depth the experimental realisation of the technique, supported by hydrodynamics simulations. With appropriate prepulse energy and timing, this blast wave can generate steepened density gradients as short as$$l\\approx 20~{\\rm\\mu}\\text{m}$$($1/e$), opening up new possibilities for laser–plasma studies with near-critical gaseous targets.« less

On the rogue waves propagation in non-Maxwellian complex space plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Tantawy, S. A., E-mail: samireltantawy@yahoo.com; El-Awady, E. I., E-mail: eielawady@hotmail.com; Tribeche, M., E-mail: mouloudtribeche@yahoo.fr, E-mail: mtribeche@usthb.dz

2015-11-15

The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that themore » RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.« less

Final Scientific/Technical Report: Correlations and Fluctuations in Weakly Collisional Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skiff, Frederick

Plasma is a state of matter that exhibits a very rich range of phenomena. To begin with, plasma is both electrical and mechanical - bringing together theories of particle motion and the electromagnetic field. Furthermore, and especially important for this project, a weakly-collisional plasma, such as is found in high-temperature (fusion energy) experiments on earth and the majority of contexts in space and astrophysics, has many moving parts. For example, sitting in earth’s atmosphere we are immersed in a mechanical wave field (sound), a possibly turbulent fluid motion (wind), and an electromagnetic vector wave field with two polarizations (light). Thismore » is already enough to produce a rich range of possibilities. In plasma, the electromagnetic field is coupled to the mechanical motion of the medium because it is ionized. Furthermore, a weakly-collisional plasma supports an infinite number of mechanically independent fluids. Thus, plasmas support an infinite number of independent electromechanical waves. Much has been done to describe plasmas with "reduced models" of various kinds. The goal of this project was to both explore the validity of reduced plasma models that are in use, and to propose and validate new models of plasma motion. The primary means to his end was laboratory experiments employing both electrical probes and laser spectroscopy. Laser spectroscopy enables many techniques which can separate the spectrum of independent fluid motions in the ion phase-space. The choice was to focus on low frequency electrostatic waves because the electron motion is relatively simple, the experiments can be on a spatial scale of a few meters, and all the relevant parameters can be measured with a few lasers systems. No study of this kind had previously been undertaken for the study of plasmas. The validation of theories required that the experimental descriptions be compared with theory and simulation in detail. It was found that even multi-fluid theories leave out a large part of the complexity of plasma motion. Reduced descriptions were found to fail under most circumstances. A new technique was developed that enabled a measurement of the phase-space resolved ion correlation function for the first time. The wide range of plasma dynamics possible became clear through this technique. It was found that collisionless (Vlasov) theory has a large field of application even when the plasma is weakly-collisional. A new approach, the kinetic wave expansion, was proposed, tested and found to be very useful for describing electrostatic ion waves. This project demonstrated a new way of looking at the "degrees-of-freedom" of plasmas and provided significant validation tests of fluid and kinetic plasma descriptions.« less

Effect of externally applied periodic force on ion acoustic waves in superthermal plasmas

NASA Astrophysics Data System (ADS)

Chowdhury, Snigdha; Mandi, Laxmikanta; Chatterjee, Prasanta

2018-04-01

Ion acoustic solitary waves in superthermal plasmas are investigated in the presence of trapped electrons. The reductive perturbation technique is employed to obtain a forced Korteweg-de Vries-like Schamel equation. An analytical solution is obtained in the presence of externally applied force. The effect of the external applied periodic force is also observed. The effect of the spectral index (κ), the strength ( f 0 ) , and the frequency ( ω ) on the amplitude and width of the solitary wave is obtained. The result may be useful in laboratory plasma as well as space environments.

Instability due to trapped electrons in magnetized multi-ion dusty plasmas

NASA Astrophysics Data System (ADS)

Haider, M. M.; Ferdous, T.; Duha, S. S.

2015-05-01

An attempt has been made to find out the effects of trapped electrons in dust-ion-acoustic solitary waves in magnetized multi-ion plasmas, as in most space plasmas, the hot electrons follow the trapped/vortex-like distribution. To do so, we have derived modified Zakharov-Kuznetsov equation using reductive perturbation method and its solution. A small- perturbation technique was employed to find out the instability criterion and growth rate of such a wave.

Experimental Investigation of Laser-sustained Plasma in Supersonic Argon Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sperber, David; Eckel, Hans-Albert; Moessinger, Peter

Laser-induced energy deposition is widely discussed as a flow control technique in supersonic transportation. In case of thermal laser-plasma upstream of a blunt body, a substantial adaptation of shock wave geometry and magnitude of wave drag is predicted. Related to the research on laser supported detonation, the paper describes the implementation of laser-sustained plasma in a supersonic Argon jet. The stable plasma state is generated by the intersection of a Q-switched Nd:YAG-laser and a continuous wave CO{sub 2}-laser beams, for ignition and maintenance of the plasma respectively. A miniature supersonic Ludwieg tube test facility generates a supersonic jet at velocitiesmore » of Mach 2.1. Modifications of the flow and plasma conditions are investigated and characterized by Schlieren flow visualisation, laser energy transmission and plasma radiation measurements. The results include the discussions of the flow field as well as the required laser and gas parameters.« less

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

NASA Astrophysics Data System (ADS)

Kazakov, Ye. O.; Ongena, J.; Wright, J. C.; Wukitch, S. J.; Lerche, E.; Mantsinen, M. J.; van Eester, D.; Craciunescu, T.; Kiptily, V. G.; Lin, Y.; Nocente, M.; Nabais, F.; Nave, M. F. F.; Baranov, Y.; Bielecki, J.; Bilato, R.; Bobkov, V.; Crombé, K.; Czarnecka, A.; Faustin, J. M.; Felton, R.; Fitzgerald, M.; Gallart, D.; Giacomelli, L.; Golfinopoulos, T.; Hubbard, A. E.; Jacquet, Ph.; Johnson, T.; Lennholm, M.; Loarer, T.; Porkolab, M.; Sharapov, S. E.; Valcarcel, D.; van Schoor, M.; Weisen, H.; Marmar, E. S.; Baek, S. G.; Barnard, H.; Bonoli, P.; Brunner, D.; Candy, J.; Canik, J.; Churchill, R. M.; Cziegler, I.; Dekow, G.; Delgado-Aparicio, L.; Diallo, A.; Edlund, E.; Ennever, P.; Faust, I.; Fiore, C.; Gao, Chi; Golfinopoulos, T.; Greenwald, M.; Hartwig, Z. S.; Holland, C.; Hubbard, A. E.; Hughes, J. W.; Hutchinson, I. H.; Irby, J.; Labombard, B.; Lin, Yijun; Lipschultz, B.; Loarte, A.; Mumgaard, R.; Parker, R. R.; Porkolab, M.; Reinke, M. L.; Rice, J. E.; Scott, S.; Shiraiwa, S.; Snyder, P.; Sorbom, B.; Terry, D.; Terry, J. L.; Theiler, C.; Vieira, R.; Walk, J. R.; Wallace, G. M.; White, A.; Whyte, D.; Wolfe, S. M.; Wright, G. M.; Wright, J.; Wukitch, S. J.; Xu, P.; Abduallev, S.; Abhangi, M.; Abreu, P.; Afzal, M.; Aggarwal, K. M.; Ahlgren, T.; Ahn, J. H.; Aho-Mantila, L.; Aiba, N.; Airila, M.; Albanese, R.; Aldred, V.; Alegre, D.; Alessi, E.; Aleynikov, P.; Alfier, A.; Alkseev, A.; Allinson, M.; Alper, B.; Alves, E.; Ambrosino, G.; Ambrosino, R.; Amicucci, L.; Amosov, V.; Sundén, E. Andersson; Angelone, M.; Anghel, M.; Angioni, C.; Appel, L.; Appelbee, C.; Arena, P.; Ariola, M.; Arnichand, H.; Arshad, S.; Ash, A.; Ashikawa, N.; Aslanyan, V.; Asunta, O.; Auriemma, F.; Austin, Y.; Avotina, L.; Axton, M. D.; Ayres, C.; Bacharis, M.; Baciero, A.; Baião, D.; Bailey, S.; Baker, A.; Balboa, I.; Balden, M.; Balshaw, N.; Bament, R.; Banks, J. W.; Baranov, Y. F.; Barnard, M. A.; Barnes, D.; Barnes, M.; Barnsley, R.; Wiechec, A. Baron; Orte, L. Barrera; Baruzzo, M.; Basiuk, V.; Bassan, M.; Bastow, R.; Batista, A.; Batistoni, P.; Baughan, R.; Bauvir, B.; Baylor, L.; Bazylev, B.; Beal, J.; Beaumont, P. S.; Beckers, M.; Beckett, B.; Becoulet, A.; Bekris, N.; Beldishevski, M.; Bell, K.; Belli, F.; Bellinger, M.; Belonohy, É.; Ayed, N. Ben; Benterman, N. A.; Bergsåker, H.; Bernardo, J.; Bernert, M.; Berry, M.; Bertalot, L.; Besliu, C.; Beurskens, M.; Bieg, B.; Bielecki, J.; Biewer, T.; Bigi, M.; Bílková, P.; Binda, F.; Bisoffi, A.; Bizarro, J. P. S.; Björkas, C.; Blackburn, J.; Blackman, K.; Blackman, T. R.; Blanchard, P.; Blatchford, P.; Bobkov, V.; Boboc, A.; Bodnár, G.; Bogar, O.; Bolshakova, I.; Bolzonella, T.; Bonanomi, N.; Bonelli, F.; Boom, J.; Booth, J.; Borba, D.; Borodin, D.; Borodkina, I.; Botrugno, A.; Bottereau, C.; Boulting, P.; Bourdelle, C.; Bowden, M.; Bower, C.; Bowman, C.; Boyce, T.; Boyd, C.; Boyer, H. J.; Bradshaw, J. M. A.; Braic, V.; Bravanec, R.; Breizman, B.; Bremond, S.; Brennan, P. D.; Breton, S.; Brett, A.; Brezinsek, S.; Bright, M. D. J.; Brix, M.; Broeckx, W.; Brombin, M.; Brosławski, A.; Brown, D. P. D.; Brown, M.; Bruno, E.; Bucalossi, J.; Buch, J.; Buchanan, J.; Buckley, M. A.; Budny, R.; Bufferand, H.; Bulman, M.; Bulmer, N.; Bunting, P.; Buratti, P.; Burckhart, A.; Buscarino, A.; Busse, A.; Butler, N. K.; Bykov, I.; Byrne, J.; Cahyna, P.; Calabrò, G.; Calvo, I.; Camenen, Y.; Camp, P.; Campling, D. C.; Cane, J.; Cannas, B.; Capel, A. J.; Card, P. J.; Cardinali, A.; Carman, P.; Carr, M.; Carralero, D.; Carraro, L.; Carvalho, B. B.; Carvalho, I.; Carvalho, P.; Casson, F. J.; Castaldo, C.; Catarino, N.; Caumont, J.; Causa, F.; Cavazzana, R.; Cave-Ayland, K.; Cavinato, M.; Cecconello, M.; Ceccuzzi, S.; Cecil, E.; Cenedese, A.; Cesario, R.; Challis, C. D.; Chandler, M.; Chandra, D.; Chang, C. S.; Chankin, A.; Chapman, I. T.; Chapman, S. C.; Chernyshova, M.; Chitarin, G.; Ciraolo, G.; Ciric, D.; Citrin, J.; Clairet, F.; Clark, E.; Clark, M.; Clarkson, R.; Clatworthy, D.; Clements, C.; Cleverly, M.; Coad, J. P.; Coates, P. A.; Cobalt, A.; Coccorese, V.; Cocilovo, V.; Coda, S.; Coelho, R.; Coenen, J. W.; Coffey, I.; Colas, L.; Collins, S.; Conka, D.; Conroy, S.; Conway, N.; Coombs, D.; Cooper, D.; Cooper, S. R.; Corradino, C.; Corre, Y.; Corrigan, G.; Cortes, S.; Coster, D.; Couchman, A. S.; Cox, M. P.; Craciunescu, T.; Cramp, S.; Craven, R.; Crisanti, F.; Croci, G.; Croft, D.; Crombé, K.; Crowe, R.; Cruz, N.; Cseh, G.; Cufar, A.; Cullen, A.; Curuia, M.; Czarnecka, A.; Dabirikhah, H.; Dalgliesh, P.; Dalley, S.; Dankowski, J.; Darrow, D.; Davies, O.; Davis, W.; Day, C.; Day, I. E.; de Bock, M.; de Castro, A.; de La Cal, E.; de La Luna, E.; Masi, G. De; de Pablos, J. L.; de Temmerman, G.; de Tommasi, G.; de Vries, P.; Deakin, K.; Deane, J.; Agostini, F. Degli; Dejarnac, R.; Delabie, E.; den Harder, N.; Dendy, R. O.; Denis, J.; Denner, P.; Devaux, S.; Devynck, P.; Maio, F. Di; Siena, A. Di; Troia, C. Di; Dinca, P.; D'Inca, R.; Ding, B.; Dittmar, T.; Doerk, H.; Doerner, R. P.; Donné, T.; Dorling, S. E.; Dormido-Canto, S.; Doswon, S.; Douai, D.; Doyle, P. T.; Drenik, A.; Drewelow, P.; Drews, P.; Duckworth, Ph.; Dumont, R.; Dumortier, P.; Dunai, D.; Dunne, M.; Ďuran, I.; Durodié, F.; Dutta, P.; Duval, B. P.; Dux, R.; Dylst, K.; Dzysiuk, N.; Edappala, P. V.; Edmond, J.; Edwards, A. M.; Edwards, J.; Eich, Th.; Ekedahl, A.; El-Jorf, R.; Elsmore, C. G.; Enachescu, M.; Ericsson, G.; Eriksson, F.; Eriksson, J.; Eriksson, L. G.; Esposito, B.; Esquembri, S.; Esser, H. G.; Esteve, D.; Evans, B.; Evans, G. E.; Evison, G.; Ewart, G. D.; Fagan, D.; Faitsch, M.; Falie, D.; Fanni, A.; Fasoli, A.; Faustin, J. M.; Fawlk, N.; Fazendeiro, L.; Fedorczak, N.; Felton, R. C.; Fenton, K.; Fernades, A.; Fernandes, H.; Ferreira, J.; Fessey, J. A.; Février, O.; Ficker, O.; Field, A.; Fietz, S.; Figueiredo, A.; Figueiredo, J.; Fil, A.; Finburg, P.; Firdaouss, M.; Fischer, U.; Fittill, L.; Fitzgerald, M.; Flammini, D.; Flanagan, J.; Fleming, C.; Flinders, K.; Fonnesu, N.; Fontdecaba, J. M.; Formisano, A.; Forsythe, L.; Fortuna, L.; Fortuna-Zalesna, E.; Fortune, M.; Foster, S.; Franke, T.; Franklin, T.; Frasca, M.; Frassinetti, L.; Freisinger, M.; Fresa, R.; Frigione, D.; Fuchs, V.; Fuller, D.; Futatani, S.; Fyvie, J.; Gál, K.; Galassi, D.; Gałązka, K.; Galdon-Quiroga, J.; Gallagher, J.; Gallart, D.; Galvão, R.; Gao, X.; Gao, Y.; Garcia, J.; Garcia-Carrasco, A.; García-Muñoz, M.; Gardarein, J.-L.; Garzotti, L.; Gaudio, P.; Gauthier, E.; Gear, D. F.; Gee, S. J.; Geiger, B.; Gelfusa, M.; Gerasimov, S.; Gervasini, G.; Gethins, M.; Ghani, Z.; Ghate, M.; Gherendi, M.; Giacalone, J. C.; Giacomelli, L.; Gibson, C. S.; Giegerich, T.; Gil, C.; Gil, L.; Gilligan, S.; Gin, D.; Giovannozzi, E.; Girardo, J. B.; Giroud, C.; Giruzzi, G.; Glöggler, S.; Godwin, J.; Goff, J.; Gohil, P.; Goloborod'Ko, V.; Gomes, R.; Gonçalves, B.; Goniche, M.; Goodliffe, M.; Goodyear, A.; Gorini, G.; Gosk, M.; Goulding, R.; Goussarov, A.; Gowland, R.; Graham, B.; Graham, M. E.; Graves, J. P.; Grazier, N.; Grazier, P.; Green, N. R.; Greuner, H.; Grierson, B.; Griph, F. S.; Grisolia, C.; Grist, D.; Groth, M.; Grove, R.; Grundy, C. N.; Grzonka, J.; Guard, D.; Guérard, C.; Guillemaut, C.; Guirlet, R.; Gurl, C.; Utoh, H. H.; Hackett, L. J.; Hacquin, S.; Hagar, A.; Hager, R.; Hakola, A.; Halitovs, M.; Hall, S. J.; Cook, S. P. Hallworth; Hamlyn-Harris, C.; Hammond, K.; Harrington, C.; Harrison, J.; Harting, D.; Hasenbeck, F.; Hatano, Y.; Hatch, D. R.; Haupt, T. D. V.; Hawes, J.; Hawkes, N. C.; Hawkins, J.; Hawkins, P.; Haydon, P. W.; Hayter, N.; Hazel, S.; Heesterman, P. J. L.; Heinola, K.; Hellesen, C.; Hellsten, T.; Helou, W.; Hemming, O. N.; Hender, T. C.; Henderson, M.; Henderson, S. S.; Henriques, R.; Hepple, D.; Hermon, G.; Hertout, P.; Hidalgo, C.; Highcock, E. G.; Hill, M.; Hillairet, J.; Hillesheim, J.; Hillis, D.; Hizanidis, K.; Hjalmarsson, A.; Hobirk, J.; Hodille, E.; Hogben, C. H. A.; Hogeweij, G. M. D.; Hollingsworth, A.; Hollis, S.; Homfray, D. A.; Horáček, J.; Hornung, G.; Horton, A. R.; Horton, L. D.; Horvath, L.; Hotchin, S. P.; Hough, M. R.; Howarth, P. J.; Hubbard, A.; Huber, A.; Huber, V.; Huddleston, T. M.; Hughes, M.; Huijsmans, G. T. A.; Hunter, C. L.; Huynh, P.; Hynes, A. M.; Iglesias, D.; Imazawa, N.; Imbeaux, F.; Imríšek, M.; Incelli, M.; Innocente, P.; Irishkin, M.; Ivanova-Stanik, I.; Jachmich, S.; Jacobsen, A. S.; Jacquet, P.; Jansons, J.; Jardin, A.; Järvinen, A.; Jaulmes, F.; Jednoróg, S.; Jenkins, I.; Jeong, C.; Jepu, I.; Joffrin, E.; Johnson, R.; Johnson, T.; Johnston, Jane; Joita, L.; Jones, G.; Jones, T. T. C.; Hoshino, K. K.; Kallenbach, A.; Kamiya, K.; Kaniewski, J.; Kantor, A.; Kappatou, A.; Karhunen, J.; Karkinsky, D.; Karnowska, I.; Kaufman, M.; Kaveney, G.; Kazakov, Y.; Kazantzidis, V.; Keeling, D. L.; Keenan, T.; Keep, J.; Kempenaars, M.; Kennedy, C.; Kenny, D.; Kent, J.; Kent, O. N.; Khilkevich, E.; Kim, H. T.; Kim, H. S.; Kinch, A.; King, C.; King, D.; King, R. F.; Kinna, D. J.; Kiptily, V.; Kirk, A.; Kirov, K.; Kirschner, A.; Kizane, G.; Klepper, C.; Klix, A.; Knight, P.; Knipe, S. J.; Knott, S.; Kobuchi, T.; Köchl, F.; Kocsis, G.; Kodeli, I.; Kogan, L.; Kogut, D.; Koivuranta, S.; Kominis, Y.; Köppen, M.; Kos, B.; Koskela, T.; Koslowski, H. R.; Koubiti, M.; Kovari, M.; Kowalska-Strzęciwilk, E.; Krasilnikov, A.; Krasilnikov, V.; Krawczyk, N.; Kresina, M.; Krieger, K.; Krivska, A.; Kruezi, U.; Książek, I.; Kukushkin, A.; Kundu, A.; Kurki-Suonio, T.; Kwak, S.; Kwiatkowski, R.; Kwon, O. J.; Laguardia, L.; Lahtinen, A.; Laing, A.; Lam, N.; Lambertz, H. T.; Lane, C.; Lang, P. T.; Lanthaler, S.; Lapins, J.; Lasa, A.; Last, J. R.; Łaszyńska, E.; Lawless, R.; Lawson, A.; Lawson, K. D.; Lazaros, A.; Lazzaro, E.; Leddy, J.; Lee, S.; Lefebvre, X.; Leggate, H. J.; Lehmann, J.; Lehnen, M.; Leichtle, D.; Leichuer, P.; Leipold, F.; Lengar, I.; Lennholm, M.; Lerche, E.; Lescinskis, A.; Lesnoj, S.; Letellier, E.; Leyland, M.; Leysen, W.; Li, L.; Liang, Y.; Likonen, J.; Linke, J.; Linsmeier, Ch.; Lipschultz, B.; Litaudon, X.; Liu, G.; Liu, Y.; Lo Schiavo, V. P.; Loarer, T.; Loarte, A.; Lobel, R. C.; Lomanowski, B.; Lomas, P. J.; Lönnroth, J.; López, J. M.; López-Razola, J.; Lorenzini, R.; Losada, U.; Lovell, J. J.; Loving, A. B.; Lowry, C.; Luce, T.; Lucock, R. M. A.; Lukin, A.; Luna, C.; Lungaroni, M.; Lungu, C. P.; Lungu, M.; Lunniss, A.; Lupelli, I.; Lyssoivan, A.; MacDonald, N.; Macheta, P.; Maczewa, K.; Magesh, B.; Maget, P.; Maggi, C.; Maier, H.; Mailloux, J.; Makkonen, T.; Makwana, R.; Malaquias, A.; Malizia, A.; Manas, P.; Manning, A.; Manso, M. E.; Mantica, P.; Mantsinen, M.; Manzanares, A.; Maquet, Ph.; Marandet, Y.; Marcenko, N.; Marchetto, C.; Marchuk, O.; Marinelli, M.; Marinucci, M.; Markovič, T.; Marocco, D.; Marot, L.; Marren, C. A.; Marshal, R.; Martin, A.; Martin, Y.; Martín de Aguilera, A.; Martínez, F. J.; Martín-Solís, J. R.; Martynova, Y.; Maruyama, S.; Masiello, A.; Maslov, M.; Matejcik, S.; Mattei, M.; Matthews, G. F.; Maviglia, F.; Mayer, M.; Mayoral, M. L.; May-Smith, T.; Mazon, D.; Mazzotta, C.; McAdams, R.; McCarthy, P. J.; McClements, K. G.; McCormack, O.; McCullen, P. A.; McDonald, D.; McIntosh, S.; McKean, R.; McKehon, J.; Meadows, R. C.; Meakins, A.; Medina, F.; Medland, M.; Medley, S.; Meigh, S.; Meigs, A. G.; Meisl, G.; Meitner, S.; Meneses, L.; Menmuir, S.; Mergia, K.; Merrigan, I. R.; Mertens, Ph.; Meshchaninov, S.; Messiaen, A.; Meyer, H.; Mianowski, S.; Michling, R.; Middleton-Gear, D.; Miettunen, J.; Militello, F.; Militello-Asp, E.; Miloshevsky, G.; Mink, F.; Minucci, S.; Miyoshi, Y.; Mlynář, J.; Molina, D.; Monakhov, I.; Moneti, M.; Mooney, R.; Moradi, S.; Mordijck, S.; Moreira, L.; Moreno, R.; Moro, F.; Morris, A. W.; Morris, J.; Moser, L.; Mosher, S.; Moulton, D.; Murari, A.; Muraro, A.; Murphy, S.; Asakura, N. N.; Na, Y. S.; Nabais, F.; Naish, R.; Nakano, T.; Nardon, E.; Naulin, V.; Nave, M. F. F.; Nedzelski, I.; Nemtsev, G.; Nespoli, F.; Neto, A.; Neu, R.; Neverov, V. S.; Newman, M.; Nicholls, K. J.; Nicolas, T.; Nielsen, A. H.; Nielsen, P.; Nilsson, E.; Nishijima, D.; Noble, C.; Nocente, M.; Nodwell, D.; Nordlund, K.; Nordman, H.; Nouailletas, R.; Nunes, I.; Oberkofler, M.; Odupitan, T.; Ogawa, M. T.; O'Gorman, T.; Okabayashi, M.; Olney, R.; Omolayo, O.; O'Mullane, M.; Ongena, J.; Orsitto, F.; Orszagh, J.; Oswuigwe, B. I.; Otin, R.; Owen, A.; Paccagnella, R.; Pace, N.; Pacella, D.; Packer, L. W.; Page, A.; Pajuste, E.; Palazzo, S.; Pamela, S.; Panja, S.; Papp, P.; Paprok, R.; Parail, V.; Park, M.; Diaz, F. Parra; Parsons, M.; Pasqualotto, R.; Patel, A.; Pathak, S.; Paton, D.; Patten, H.; Pau, A.; Pawelec, E.; Soldan, C. Paz; Peackoc, A.; Pearson, I. J.; Pehkonen, S.-P.; Peluso, E.; Penot, C.; Pereira, A.; Pereira, R.; Puglia, P. P. Pereira; von Thun, C. Perez; Peruzzo, S.; Peschanyi, S.; Peterka, M.; Petersson, P.; Petravich, G.; Petre, A.; Petrella, N.; Petržilka, V.; Peysson, Y.; Pfefferlé, D.; Philipps, V.; Pillon, M.; Pintsuk, G.; Piovesan, P.; Dos Reis, A. Pires; Piron, L.; Pironti, A.; Pisano; Pitts, R.; Pizzo, F.; Plyusnin, V.; Pomaro, N.; Pompilian, O. G.; Pool, P. J.; Popovichev, S.; Porfiri, M. T.; Porosnicu, C.; Porton, M.; Possnert, G.; Potzel, S.; Powell, T.; Pozzi, J.; Prajapati, V.; Prakash, R.; Prestopino, G.; Price, D.; Price, M.; Price, R.; Prior, P.; Proudfoot, R.; Pucella, G.; Puglia, P.; Puiatti, M. E.; Pulley, D.; Purahoo, K.; Pütterich, Th.; Rachlew, E.; Rack, M.; Ragona, R.; Rainford, M. S. J.; Rakha, A.; Ramogida, G.; Ranjan, S.; Rapson, C. J.; Rasmussen, J. J.; Rathod, K.; Rattá, G.; Ratynskaia, S.; Ravera, G.; Rayner, C.; Rebai, M.; Reece, D.; Reed, A.; Réfy, D.; Regan, B.; Regaña, J.; Reich, M.; Reid, N.; Reimold, F.; Reinhart, M.; Reinke, M.; Reiser, D.; Rendell, D.; Reux, C.; Cortes, S. D. A. Reyes; Reynolds, S.; Riccardo, V.; Richardson, N.; Riddle, K.; Rigamonti, D.; Rimini, F. G.; Risner, J.; Riva, M.; Roach, C.; Robins, R. J.; Robinson, S. A.; Robinson, T.; Robson, D. W.; Roccella, R.; Rodionov, R.; Rodrigues, P.; Rodriguez, J.; Rohde, V.; Romanelli, F.; Romanelli, M.; Romanelli, S.; Romazanov, J.; Rowe, S.; Rubel, M.; Rubinacci, G.; Rubino, G.; Ruchko, L.; Ruiz, M.; Ruset, C.; Rzadkiewicz, J.; Saarelma, S.; Sabot, R.; Safi, E.; Sagar, P.; Saibene, G.; Saint-Laurent, F.; Salewski, M.; Salmi, A.; Salmon, R.; Salzedas, F.; Samaddar, D.; Samm, U.; Sandiford, D.; Santa, P.; Santala, M. I. K.; Santos, B.; Santucci, A.; Sartori, F.; Sartori, R.; Sauter, O.; Scannell, R.; Schlummer, T.; Schmid, K.; Schmidt, V.; Schmuck, S.; Schneider, M.; Schöpf, K.; Schwörer, D.; Scott, S. D.; Sergienko, G.; Sertoli, M.; Shabbir, A.; Sharapov, S. E.; Shaw, A.; Shaw, R.; Sheikh, H.; Shepherd, A.; Shevelev, A.; Shumack, A.; Sias, G.; Sibbald, M.; Sieglin, B.; Silburn, S.; Silva, A.; Silva, C.; Simmons, P. A.; Simpson, J.; Simpson-Hutchinson, J.; Sinha, A.; Sipilä, S. K.; Sips, A. C. C.; Sirén, P.; Sirinelli, A.; Sjöstrand, H.; Skiba, M.; Skilton, R.; Slabkowska, K.; Slade, B.; Smith, N.; Smith, P. G.; Smith, R.; Smith, T. J.; Smithies, M.; Snoj, L.; Soare, S.; Solano, E. R.; Somers, A.; Sommariva, C.; Sonato, P.; Sopplesa, A.; Sousa, J.; Sozzi, C.; Spagnolo, S.; Spelzini, T.; Spineanu, F.; Stables, G.; Stamatelatos, I.; Stamp, M. F.; Staniec, P.; Stankūnas, G.; Stan-Sion, C.; Stead, M. J.; Stefanikova, E.; Stepanov, I.; Stephen, A. V.; Stephen, M.; Stevens, A.; Stevens, B. D.; Strachan, J.; Strand, P.; Strauss, H. R.; Ström, P.; Stubbs, G.; Studholme, W.; Subba, F.; Summers, H. P.; Svensson, J.; Świderski, Ł.; Szabolics, T.; Szawlowski, M.; Szepesi, G.; Suzuki, T. T.; Tál, B.; Tala, T.; Talbot, A. R.; Talebzadeh, S.; Taliercio, C.; Tamain, P.; Tame, C.; Tang, W.; Tardocchi, M.; Taroni, L.; Taylor, D.; Taylor, K. A.; Tegnered, D.; Telesca, G.; Teplova, N.; Terranova, D.; Testa, D.; Tholerus, E.; Thomas, J.; Thomas, J. D.; Thomas, P.; Thompson, A.; Thompson, C.-A.; Thompson, V. K.; Thorne, L.; Thornton, A.; Thrysøe, A. S.; Tigwell, P. A.; Tipton, N.; Tiseanu, I.; Tojo, H.; Tokitani, M.; Tolias, P.; Tomeš, M.; Tonner, P.; Towndrow, M.; Trimble, P.; Tripsky, M.; Tsalas, M.; Tsavalas, P.; Jun, D. Tskhakaya; Turner, I.; Turner, M. M.; Turnyanskiy, M.; Tvalashvili, G.; Tyrrell, S. G. J.; Uccello, A.; Ul-Abidin, Z.; Uljanovs, J.; Ulyatt, D.; Urano, H.; Uytdenhouwen, I.; Vadgama, A. P.; Valcarcel, D.; Valentinuzzi, M.; Valisa, M.; Olivares, P. Vallejos; Valovic, M.; van de Mortel, M.; van Eester, D.; van Renterghem, W.; van Rooij, G. J.; Varje, J.; Varoutis, S.; Vartanian, S.; Vasava, K.; Vasilopoulou, T.; Vega, J.; Verdoolaege, G.; Verhoeven, R.; Verona, C.; Rinati, G. Verona; Veshchev, E.; Vianello, N.; Vicente, J.; Viezzer, E.; Villari, S.; Villone, F.; Vincenzi, P.; Vinyar, I.; Viola, B.; Vitins, A.; Vizvary, Z.; Vlad, M.; Voitsekhovitch, I.; Vondráček, P.; Vora, N.; Vu, T.; de Sa, W. W. Pires; Wakeling, B.; Waldon, C. W. F.; Walkden, N.; Walker, M.; Walker, R.; Walsh, M.; Wang, E.; Wang, N.; Warder, S.; Warren, R. J.; Waterhouse, J.; Watkins, N. W.; Watts, C.; Wauters, T.; Weckmann, A.; Weiland, J.; Weisen, H.; Weiszflog, M.; Wellstood, C.; West, A. T.; Wheatley, M. R.; Whetham, S.; Whitehead, A. M.; Whitehead, B. D.; Widdowson, A. M.; Wiesen, S.; Wilkinson, J.; Williams, J.; Williams, M.; Wilson, A. R.; Wilson, D. J.; Wilson, H. R.; Wilson, J.; Wischmeier, M.; Withenshaw, G.; Withycombe, A.; Witts, D. M.; Wood, D.; Wood, R.; Woodley, C.; Wray, S.; Wright, J.; Wright, J. C.; Wu, J.; Wukitch, S.; Wynn, A.; Xu, T.; Yadikin, D.; Yanling, W.; Yao, L.; Yavorskij, V.; Yoo, M. G.; Young, C.; Young, D.; Young, I. D.; Young, R.; Zacks, J.; Zagorski, R.; Zaitsev, F. S.; Zanino, R.; Zarins, A.; Zastrow, K. D.; Zerbini, M.; Zhang, W.; Zhou, Y.; Zilli, E.; Zoita, V.; Zoletnik, S.; Zychor, I.

2017-10-01

We describe a new technique for the efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed `three-ion' scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of the method on the world-largest plasma magnetic confinement device, JET (Joint European Torus, Culham, UK), and the high-magnetic-field tokamak Alcator C-Mod (Cambridge, USA). The obtained results demonstrate efficient acceleration of 3He ions to high energies in dedicated hydrogen-deuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast 3He ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space-plasma environments, in particular, 3He-rich solar flares.

Instantaneous polarization statistic property of EM waves incident on time-varying reentry plasma

NASA Astrophysics Data System (ADS)

Bai, Bowen; Liu, Yanming; Li, Xiaoping; Yao, Bo; Shi, Lei

2018-06-01

An analytical method is proposed in this paper to study the effect of time-varying reentry plasma sheath on the instantaneous polarization statistic property of electromagnetic (EM) waves. Based on the disturbance property of the hypersonic fluid, the spatial-temporal model of the time-varying reentry plasma sheath is established. An analytical technique referred to as transmission line analogy is developed to calculate the instantaneous transmission coefficient of EM wave propagation in time-varying plasma. Then, the instantaneous polarization statistic theory of EM wave propagation in the time-varying plasma sheath is developed. Taking the S-band telemetry right hand circularly polarized wave as an example, effects of incident angle and plasma parameters, including the electron density and the collision frequency on the EM wave's polarization statistic property are studied systematically. Statistical results indicate that the lower the collision frequency and the larger the electron density and incident angle is, the worse the deterioration of the polarization property is. Meanwhile, in conditions of critical parameters of certain electron density, collision frequency, and incident angle, the transmitted waves have both the right and left hand polarization mode, and the polarization mode will reverse. The calculation results could provide useful information for adaptive polarization receiving of the spacecraft's reentry communication.

Instabilities and turbulence in highly ionized plasmas in a magnetic field

NASA Technical Reports Server (NTRS)

Jennings, W. C.

1972-01-01

Physical mechanisms were considered which are responsible for plasma turbulence and the establishment of necessary conditions for energy exchange and transfer in the frequency spectrum. In addition, work was performed to better understand the drift instability in the highly inhomogeneous Rensselaer arc, and methods to suppress this instability using feedback stabilization techniques. Correlation techniques were refined to study plasma turbulence, the diffusion wave technique for monitoring cross-field diffusion was extended to include regimes of high turbulence levels, and a technique for coupling stabilizing RF power to the Rensselaer arc was developed.

Electron Energy Distribution function in a weakly magnetized expanding helicon plasma discharge

NASA Astrophysics Data System (ADS)

Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

2016-09-01

Helicon wave heating is well known to produce high-density plasma source for application in plasma thrusters, plasma processing and many more. Our previous study (B Ellingboe et al. APS Gaseous Electronics Conference 2015, abstract #KW2.005) has shown observation of helicon wave in a weakly magnetized inductively coupled plasma source excited by m =0 antenna at 13.56 MHz. In this paper, we investigated the Electron Energy Distribution Function (EEDF) in the same setup by using an RF compensated Langmuir probe. The ac signal superimposition technique (second harmonic technique) is used to determine EEDF. The EEDF is measured for 5-100 mTorr gas pressure, 100 W - 1.5 kW rf power and at different locations in the source chamber, boundary and diffusion chamber. This paper will discuss the change in the shape of EEDF for various heating mode transitions.

Nonlinear Dust Acoustic Waves in a Magnetized Dusty Plasma with Trapped and Superthermal Electrons

NASA Astrophysics Data System (ADS)

Ahmadi, Abrishami S.; Nouri, Kadijani M.

2014-06-01

In this work, the effects of superthermal and trapped electrons on the oblique propagation of nonlinear dust-acoustic waves in a magnetized dusty (complex) plasma are investigated. The dynamic of electrons is simulated by the generalized Lorentzian (κ) distribution function (DF). The dust grains are cold and their dynamics are simulated by hydrodynamic equations. Using the standard reductive perturbation technique (RPT) a nonlinear modified Korteweg-de Vries (mKdV) equation is derived. Two types of solitary waves; fast and slow dust acoustic solitons, exist in this plasma. Calculations reveal that compressive solitary structures are likely to propagate in this plasma where dust grains are negatively (or positively) charged. The properties of dust acoustic solitons (DASs) are also investigated numerically.

Laser-launched flyer plate and confined laser ablation for shock wave loading: validation and applications.

PubMed

Paisley, Dennis L; Luo, Sheng-Nian; Greenfield, Scott R; Koskelo, Aaron C

2008-02-01

We present validation and some applications of two laser-driven shock wave loading techniques: laser-launched flyer plate and confined laser ablation. We characterize the flyer plate during flight and the dynamically loaded target with temporally and spatially resolved diagnostics. With transient imaging displacement interferometry, we demonstrate that the planarity (bow and tilt) of the loading induced by a spatially shaped laser pulse is within 2-7 mrad (with an average of 4+/-1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible, in particular, when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation allows for flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These techniques can be utilized to investigate such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples.

Wave Telescope Technique for MMS Magnetometer

NASA Technical Reports Server (NTRS)

Narita, Y.; Plaschke, F.; Nakamura, R.; Baumjojann, W.; Magnes, W.; Fischer, D.; Voros, Z.; Torbert, R. B.; Russell, C. T.; Strangeway, R. J.;

Strong Langmuir Turbulence and Four-Wave Mixing

NASA Astrophysics Data System (ADS)

Glanz, James

1991-02-01

The staircase expansion is a new mathematical technique for deriving reduced, nonlinear-PDE descriptions from the plasma-moment equations. Such descriptions incorporate only the most significant linear and nonlinear terms of more complex systems. The technique is used to derive a set of Dawson-Zakharov or "master" equations, which unify and generalize previous work and show the limitations of models commonly used to describe nonlinear plasma waves. Fundamentally new wave-evolution equations are derived that admit of exact nonlinear solutions (solitary waves). Analytic calculations illustrate the competition between well-known effects of self-focusing, which require coupling to ion motion, and pure-electron nonlinearities, which are shown to be especially important in curved geometries. Also presented is an N -moment hydrodynamic model derived from the Vlasov equation. In this connection, the staircase expansion is shown to remain useful for all values of N >= 3. The relevance of the present work to nonlocally truncated hierarchies, which more accurately model dissipation, is briefly discussed. Finally, the general formalism is applied to the problem of electromagnetic emission from counterpropagating Langmuir pumps. It is found that previous treatments have neglected order-unity effects that increase the emission significantly. Detailed numerical results are presented to support these conclusions. The staircase expansion--so called because of its appearance when written out--should be effective whenever the largest contribution to the nonlinear wave remains "close" to some given frequency. Thus the technique should have application to studies of wake-field acceleration schemes and anomalous damping of plasma waves.

Electrostatic wave modulation in collisional pair-ion plasmas

NASA Astrophysics Data System (ADS)

Sikdar, Arnab; Adak, Ashish; Ghosh, Samiran; Khan, Manoranjan

2018-05-01

The effects of ion-neutral collision on the electrostatic wave packets in the absence of the magnetic field in a pair-ion plasma have been investigated. Considering a two-fluid plasma model with the help of the standard perturbation technique, two distinct electrostatic modes have been observed, namely, a low-frequency ion acoustic mode and a high-frequency ion plasma mode. The dynamics of the modulated wave is governed by a damped nonlinear Schrödinger equation. Damping of the soliton occurs due to the ion-neutral collision. The analytical and numerical investigation reveals that the ion acoustic mode is both stable and unstable, which propagates in the form of dark solitons and bright solitons, respectively, whereas the ion plasma mode is unstable, propagating in the form of a bright soliton. Results are discussed in the context of the fullerene pair-ion plasma experiments.

Nonlinear Korteweg-de Vries-Burger equation for ion acoustic shock waves in a weakly relativistic electron-positron-ion plasma with thermal ions

NASA Astrophysics Data System (ADS)

Saeed, R.; Shah, Asif

2010-03-01

The nonlinear propagation of ion acoustic waves in electron-positron-ion plasma comprising of Boltzmannian electrons, positrons, and relativistic thermal ions has been examined. The Korteweg-de Vries-Burger equation has been derived by reductive perturbation technique, and its shock like solution is determined analytically through tangent hyperbolic method. The effect of various plasma parameters on strength and structure of shock wave is investigated. The pert graphical view of the results has been presented for illustration. It is observed that strength and steepness of the shock wave enervate with an increase in the ion temperature, relativistic streaming factor, positron concentrations, electron temperature and they accrue with an increase in coefficient of kinematic viscosity. The convective, dispersive, and dissipative properties of the plasma are also discussed. It is determined that the electron temperature has remarkable influence on the propagation and structure of nonlinear wave in such relativistic plasmas. The numerical analysis has been done based on the typical numerical data from a pulsar magnetosphere.

A determination of relativistic shock jump conditions using Monte Carlo techniques

NASA Technical Reports Server (NTRS)

Ellison, Donald C.; Reynolds, Stephen P.

1991-01-01

Monte Carlo techniques are used, assuming isotropic elastic scattering of all particles, to calculate jump conditions in parallel relativistic collisionless shocks in the absence of Fermi acceleration. The shock velocity and compression ratios are shown for arbitrary flow velocities and for any upstream temperature. Both single-component electron-positron plasma and two-component proton-electron plasmas are considered. It is shown that protons and electrons must share energy, directly or through the mediation of plasma waves, in order to satisfy the basic conservation conditions, and the electron and proton temperatures are determined for a particular microscopic, kinetic-theory model, namely, that protons always scatter elastically. The results are directly applicable to shocks in which waves of scattering superthermal particles are absent.

Revisiting linear plasma waves for finite value of the plasma parameter

NASA Astrophysics Data System (ADS)

Grismayer, Thomas; Fahlen, Jay; Decyk, Viktor; Mori, Warren

2010-11-01

We investigate through theory and PIC simulations the Landau-damping of plasma waves with finite plasma parameter. We concentrate on the linear regime, γφB, where the waves are typically small and below the thermal noise. We simulate these condition using 1,2,3D electrostatic PIC codes (BEPS), noting that modern computers now allow us to simulate cases where (nλD^3 = [1e2;1e6]). We study these waves by using a subtraction technique in which two simulations are carried out. In the first, a small wave is initialized or driven, in the second no wave is excited. The results are subtracted to provide a clean signal that can be studied. As nλD^3 is decreased, the number of resonant electrons can be small for linear waves. We show how the damping changes as a result of having few resonant particles. We also find that for small nλD^3 fluctuations can cause the electrons to undergo collisions that eventually destroy the initial wave. A quantity of interest is the the life time of a particular mode which depends on the plasma parameter and the wave number. The life time is estimated and then compared with the numerical results. A surprising result is that even for large values of nλD^3 some non-Vlasov discreteness effects appear to be important.

High-resolution studies of the HF ionospheric modification interaction region

NASA Technical Reports Server (NTRS)

Duncan, L. M.; Sheerin, J. P.

1985-01-01

The use of the pulse edge analysis technique to explain ionospheric modifications caused by high-power HF radio waves is discussed. The technique, implemented at the Arecibo Observatory, uses long radar pulses and very rapid data sampling. A comparison of the pulse leading and trailing edge characteristics is obtained and the comparison is used to estimate the relative changes in the interaction region height and layer width; an example utilizing this technique is provided. Main plasma line overshoot and miniovershoot were studied from the pulse edge observations; the observations at various HF pulsings and radar resolutions are graphically presented. From the pulse edge data the development and the occurrence of main plasma line overshoot and miniovershoot are explained. The theories of soliton formation and collapse, wave ducting, profile modification, and parametric instabilities are examined as a means of explaining main plasma line overshoots and miniovershoots.

Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rufai, O. R.; Bharuthram, R.; Singh, S. V.

2012-12-15

Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to bemore » 49 mV/m which is in agreement of the Viking observations in this region.« less

Laser-Plasma Instabilities by Avoiding the Strong Ion Landau Damping Limit: The Central Role of Statistical, Ultrafast, Nonlinear Optical Laser Techniques (SUNOL)

NASA Astrophysics Data System (ADS)

Afeyan, Bedros; Hüller, Stefan; Montgomery, David; Moody, John; Froula, Dustin; Hammer, James; Jones, Oggie; Amendt, Peter

2014-10-01

In mid-Z and high-Z plasmas, it is possible to control crossed bean energy transfer (CBET) and subsequently occurring single or multiple beam instabilities such as Stimulated Raman Scattering (SRS) by novel means. These new techniques are inoperative when the ion acoustic waves are in their strong damping limit, such as occurs in low Z plasmas with comparable electron and ion temperatures. For mid-Z plasmas, such as Z = 10, and near the Mach 1 surface, the strong coupling regime (SCR) can be exploited for LPI mitigation. While at higher Z values, it is thermal filamentation in conjunction with nonlocal heat transport that are useful to exploit. In both these settings, the strategy is to induce laser hot spot intensity dependent, and thus spatially dependent, frequency shifts to the ion acoustic waves in the transient response of wave-wave interactions. The latter is achieved by the on-off nature of spike trains of uneven duration and delay, STUD pulses. The least taxing use of STUD pulses is to modulate the beams at the 10 ps time scale and to choose which crossing beams are overlapping in time and which are not. Work supported by a grant from the DOE NNSA-OFES joint program on HEDP

Modifying the ionosphere with intense radio waves.

PubMed

Utlaut, W F; Cohen, R

1971-10-15

The ionospheric modification experiments provide an opportunity to better understand the aeronomy of the natural ionosphere and also afford the control of a naturally occurring plasma, which will make possible further progress in plasma physics. The ionospheric modification by powerful radio waves is analogous to studies of laser and microwave heating of laboratory plasmas (20). " Anomalous" reflectivity effects similar to the observed ionospheric attenuation have already been noted in plasmas modulated by microwaves, and anomalous heating may have been observed in plasmas irradiated by lasers. Contacts have now been established between the workers in these diverse areas, which span a wide range of the electromagnetic spectrum. Perhaps ionospheric modification will also be a valuable technique in radio communications.

Plasmon resonances, anomalous transparency, and reflectionless absorption in overdense plasmas

NASA Astrophysics Data System (ADS)

Smolyakov, A.; Sternberg, N.

2018-03-01

The structure of the surface and standing wave resonances and their coupling in the configuration of the overdense plasma slab with a single diffraction grating are studied, using impedance matching techniques. Analytical criteria and exact expressions are obtained for plasma and diffraction grating parameters which define resonance conditions for absolute transparency in the ideal plasma and reflectionless absorption in a plasma with dissipation.

Nonplanar KdV and KP equations for quantum electron-positron-ion plasma

NASA Astrophysics Data System (ADS)

Dutta, Debjit

2015-12-01

Nonlinear quantum ion-acoustic waves with the effects of nonplanar cylindrical geometry, quantum corrections, and transverse perturbations are studied. By using the standard reductive perturbation technique, a cylindrical Kadomtsev-Petviashvili equation for ion-acoustic waves is derived by incorporating quantum-mechanical effects. The quantum-mechanical effects via quantum diffraction and quantum statistics and the role of transverse perturbations in cylindrical geometry on the dynamics of this wave are studied analytically. It is found that the dynamics of ion-acoustic solitary waves (IASWs) is governed by a three-dimensional cylindrical Kadomtsev-Petviashvili equation (CKPE). The results could help in a theoretical analysis of astrophysical and laser produced plasmas.

An accurate automated technique for quasi-optics measurement of the microwave diagnostics for fusion plasma

NASA Astrophysics Data System (ADS)

Hu, Jianqiang; Liu, Ahdi; Zhou, Chu; Zhang, Xiaohui; Wang, Mingyuan; Zhang, Jin; Feng, Xi; Li, Hong; Xie, Jinlin; Liu, Wandong; Yu, Changxuan

2017-08-01

A new integrated technique for fast and accurate measurement of the quasi-optics, especially for the microwave/millimeter wave diagnostic systems of fusion plasma, has been developed. Using the LabVIEW-based comprehensive scanning system, we can realize not only automatic but also fast and accurate measurement, which will help to eliminate the effects of temperature drift and standing wave/multi-reflection. With the Matlab-based asymmetric two-dimensional Gaussian fitting method, all the desired parameters of the microwave beam can be obtained. This technique can be used in the design and testing of microwave diagnostic systems such as reflectometers and the electron cyclotron emission imaging diagnostic systems of the Experimental Advanced Superconducting Tokamak.

Multifluid Theory of Solitons

NASA Astrophysics Data System (ADS)

Verheest, Frank

2008-03-01

After introducing the basic multifluid model equations, this review discusses three different methods to describe nonlinear plasma waves, by giving a rather general overview of the relevant methodology, followed by a specific and recent application. First, reductive perturbation analysis is applicable to waves that are not too strongly nonlinear, if their linear counterparts have an acoustic-like dispersion at low frequencies. It is discussed for electrostatic modes, with a brief application to dusty plasma waves. The typical paradigm for such problems is the well known KdV equation and its siblings. Stationary waves with larger amplitudes can be treated, i.a., via the fluid-dynamic approach pioneered by McKenzie, which focuses on essential insights into the limitations that restrict the range of available solitary electrostatic solutions. As an illustration, novel electrostatic solutions have been found in plasmas with two-temperature electron species that are relevant in understanding certain magnetospheric plasma observations. The older cousin of the large-amplitude technique is the Sagdeev pseudopotential description, to which the newer fluid-dynamic approach is essentially equivalent. Because the Sagdeev analysis has mostly been applied to electrostatic waves, some recent results are given for electromagnetic modes in pair plasmas, to show its versatility.

Stable and unstable roots of ion temperature gradient driven mode using curvature modified plasma dispersion functions

NASA Astrophysics Data System (ADS)

Gültekin, Ö.; Gürcan, Ö. D.

2018-02-01

Basic, local kinetic theory of ion temperature gradient driven (ITG) mode, with adiabatic electrons is reconsidered. Standard unstable, purely oscillating as well as damped solutions of the local dispersion relation are obtained using a bracketing technique that uses the argument principle. This method requires computing the plasma dielectric function and its derivatives, which are implemented here using modified plasma dispersion functions with curvature and their derivatives, and allows bracketing/following the zeros of the plasma dielectric function which corresponds to different roots of the ITG dispersion relation. We provide an open source implementation of the derivatives of modified plasma dispersion functions with curvature, which are used in this formulation. Studying the local ITG dispersion, we find that near the threshold of instability the unstable branch is rather asymmetric with oscillating solutions towards lower wave numbers (i.e. drift waves), and damped solutions toward higher wave numbers. This suggests a process akin to inverse cascade by coupling to the oscillating branch towards lower wave numbers may play a role in the nonlinear evolution of the ITG, near the instability threshold. Also, using the algorithm, the linear wave diffusion is estimated for the marginally stable ITG mode.

Mirror Langmuir probe: a technique for real-time measurement of magnetized plasma conditions using a single Langmuir electrode.

PubMed

LaBombard, B; Lyons, L

2007-07-01

A new method for the real-time evaluation of the conditions in a magnetized plasma is described. The technique employs an electronic "mirror Langmuir probe" (MLP), constructed from bipolar rf transistors and associated high-bandwidth electronics. Utilizing a three-state bias wave form and active feedback control, the mirror probe's I-V characteristic is continuously adjusted to be a scaled replica of the "actual" Langmuir electrode immersed in a plasma. Real-time high-bandwidth measurements of the plasma's electron temperature, ion saturation current, and floating potential can thereby be obtained using only a single electrode. Initial tests of a prototype MLP system are reported, proving the concept. Fast-switching metal-oxide-semiconductor field-effect transistors produce the required three-state voltage bias wave form, completing a full cycle in under 1 mus. Real-time outputs of electron temperature, ion saturation current, and floating potential are demonstrated, which accurately track an independent computation of these values from digitally stored I-V characteristics. The MLP technique represents a significant improvement over existing real-time methods, eliminating the need for multiple electrodes and sampling all three plasma parameters at a single spatial location.

Development of a GPU-Accelerated 3-D Full-Wave Code for Electromagnetic Wave Propagation in a Cold Plasma

NASA Astrophysics Data System (ADS)

Woodbury, D.; Kubota, S.; Johnson, I.

2014-10-01

Computer simulations of electromagnetic wave propagation in magnetized plasmas are an important tool for both plasma heating and diagnostics. For active millimeter-wave and microwave diagnostics, accurately modeling the evolution of the beam parameters for launched, reflected or scattered waves in a toroidal plasma requires that calculations be done using the full 3-D geometry. Previously, we reported on the application of GPGPU (General-Purpose computing on Graphics Processing Units) to a 3-D vacuum Maxwell code using the FDTD (Finite-Difference Time-Domain) method. Tests were done for Gaussian beam propagation with a hard source antenna, utilizing the parallel processing capabilities of the NVIDIA K20M. In the current study, we have modified the 3-D code to include a soft source antenna and an induced current density based on the cold plasma approximation. Results from Gaussian beam propagation in an inhomogeneous anisotropic plasma, along with comparisons to ray- and beam-tracing calculations will be presented. Additional enhancements, such as advanced coding techniques for improved speedup, will also be investigated. Supported by U.S. DoE Grant DE-FG02-99-ER54527 and in part by the U.S. DoE, Office of Science, WDTS under the Science Undergraduate Laboratory Internship program.

Dust ion acoustic freak waves in a plasma with two temperature electrons featuring Tsallis distribution

NASA Astrophysics Data System (ADS)

Chahal, Balwinder Singh; Singh, Manpreet; Shalini; Saini, N. S.

2018-02-01

We present an investigation for the nonlinear dust ion acoustic wave modulation in a plasma composed of charged dust grains, two temperature (cold and hot) nonextensive electrons and ions. For this purpose, the multiscale reductive perturbation technique is used to obtain a nonlinear Schrödinger equation. The critical wave number, which indicates where the modulational instability sets in, has been determined precisely for various regimes. The influence of plasma background nonextensivity on the growth rate of modulational instability is discussed. The modulated wavepackets in the form of either bright or dark type envelope solitons may exist. Formation of rogue waves from bright envelope solitons is also discussed. The investigation indicates that the structural characteristics of these envelope excitations (width, amplitude) are significantly affected by nonextensivity, dust concentration, cold electron-ion density ratio and temperature ratio.

Dust acoustic cnoidal waves in a polytropic complex plasma

NASA Astrophysics Data System (ADS)

El-Labany, S. K.; El-Taibany, W. F.; Abdelghany, A. M.

2018-01-01

The nonlinear characteristics of dust acoustic (DA) waves in an unmagnetized collisionless complex plasma containing adiabatic electrons and ions and negatively charged dust grains (including the effects of modified polarization force) are investigated. Employing the reductive perturbation technique, a Korteweg-de Vries-Burgers (KdVB) equation is derived. The analytical solution for the KdVB equation is discussed. Also, the bifurcation and phase portrait analyses are presented to recognize different types of possible solutions. The dependence of the properties of nonlinear DA waves on the system parameters is investigated. It has been shown that an increase in the value of the modified polarization parameter leads to a fast decay and diminishes the oscillation amplitude of the DA damped cnoidal wave. The relevance of our findings and their possible applications to laboratory and space plasma situations is discussed.

Detection of swine-origin influenza A (H1N1) viruses using a paired surface plasma waves biosensor

NASA Astrophysics Data System (ADS)

Su, Li-Chen; Chang, Ying-Feng; Li, Ying-Chang; Hsieh, Jo-Ping; Lee, Cheng-Chung; Chou, Chien

2010-08-01

In order to enhance the sensitivity of conventional rapid test technique for the detection of swine-origin influenza A (H1N1) viruses (S-OIVs), we used a paired surface plasma waves biosensor (PSPWB) based on SPR in conjunction with an optical heterodyne technique. Experimentally, PSPWB showed a 125-fold improvement at least in the S-OIV detection as compared to conventional enzyme linked immunosorbent assay. Moreover, the detection limit of the PSPWB for the S-OIV detection was enhanced 250-fold in buffer at least in comparison with that of conventional rapid influenza diagnostic test.

Electric field determination in the plasma-antenna boundary of a lower-hybrid wave launcher in Tore Supra through dynamic Stark-effect spectroscopy

NASA Astrophysics Data System (ADS)

Martin, E. H.; Goniche, M.; Klepper, C. C.; Hillairet, J.; Isler, R. C.; Bottereau, C.; Colas, L.; Ekedahl, A.; Panayotis, S.; Pegourie, B.; Lotte, Ph; Colledani, G.; Caughman, J. B.; Harris, J. H.; Hillis, D. L.; Shannon, S. C.; Clairet, F.; Litaudon, X.

2015-06-01

Interaction of radio-frequency (RF) waves with the plasma in the near-field of a high-power wave launcher is now seen to be an important topic, both in understanding the channeling of these waves through the plasma boundary and in avoiding power losses in the edge. In a recent Letter, a direct non-intrusive measurement of a near antenna RF electric field in the range of lower hybrid (LH) frequencies (ELH) was announced (2013 Phys. Rev. Lett. 110 215005). This measurement was achieved through the fitting of Balmer series deuterium spectral lines utilizing a time dependent (dynamic) Stark effect model. In this article, the analysis of the spectral data is discussed in detail and applied to a larger range of measurements and the accuracy and limitations of the experimental technique are investigated. It was found through an analysis of numerous Tore Supra discharges that good quantitative agreement exists between the measured and full-wave modeled ELH when the launched power exceeds 0.5 MW. For low power the measurement becomes inaccurate utilizing the implemented passive spectroscopic technique because the spectral noise overwhelms the effect of the RF electric field on the line profile. Additionally, effects of the ponderomotive force are suspected at sufficiently high power.

Plasma Diagnostics by Antenna Impedance Measurements

NASA Technical Reports Server (NTRS)

Swenson, C. M.; Baker, K. D.; Pound, E.; Jensen, M. D.

1993-01-01

The impedance of an electrically short antenna immersed in a plasma provides an excellent in situ diagnostic tool for electron density and other plasma parameters. By electrically short we mean that the wavelength of the free-space electromagnetic wave that would be excited at the driving frequency is much longer than the physical size of the antenna. Probes using this impedance technique have had a long history with sounding rockets and satellites, stretching back to the early 1960s. This active technique could provide information on composition and temperature of plasmas for comet or planetary missions. Advantages of the impedance probe technique are discussed and two classes of instruments built and flown by SDL-USU for determining electron density (the capacitance and plasma frequency probes) are described.

Development of full wave code for modeling RF fields in hot non-uniform plasmas

NASA Astrophysics Data System (ADS)

Zhao, Liangji; Svidzinski, Vladimir; Spencer, Andrew; Kim, Jin-Soo

2016-10-01

FAR-TECH, Inc. is developing a full wave RF modeling code to model RF fields in fusion devices and in general plasma applications. As an important component of the code, an adaptive meshless technique is introduced to solve the wave equations, which allows resolving plasma resonances efficiently and adapting to the complexity of antenna geometry and device boundary. The computational points are generated using either a point elimination method or a force balancing method based on the monitor function, which is calculated by solving the cold plasma dispersion equation locally. Another part of the code is the conductivity kernel calculation, used for modeling the nonlocal hot plasma dielectric response. The conductivity kernel is calculated on a coarse grid of test points and then interpolated linearly onto the computational points. All the components of the code are parallelized using MPI and OpenMP libraries to optimize the execution speed and memory. The algorithm and the results of our numerical approach to solving 2-D wave equations in a tokamak geometry will be presented. Work is supported by the U.S. DOE SBIR program.

Small amplitude two dimensional electrostatic excitations in a magnetized dusty plasma with q-distributed electrons

NASA Astrophysics Data System (ADS)

Khan, Shahab Ullah; Adnan, Muhammad; Qamar, Anisa; Mahmood, Shahzad

2016-07-01

The propagation of linear and nonlinear electrostatic waves is investigated in magnetized dusty plasma with stationary negatively or positively charged dust, cold mobile ions and non-extensive electrons. Two normal modes are predicted in the linear regime, whose characteristics are investigated parametrically, focusing on the effect of electrons non-extensivity, dust charge polarity, concentration of dust and magnetic field strength. Using the reductive perturbation technique, a Zakharov-Kuznetsov (ZK) type equation is derived which governs the dynamics of small-amplitude solitary waves in magnetized dusty plasma. The properties of the solitary wave structures are analyzed numerically with the system parameters i.e. electrons non-extensivity, concentration of dust, polarity of dust and magnetic field strength. Following Allen and Rowlands (J. Plasma Phys. 53:63, 1995), we have shown that the pulse soliton solution of the ZK equation is unstable, and have analytically traced the dependence of the instability growth rate on the nonextensive parameter q for electrons, dust charge polarity and magnetic field strength. The results should be useful for understanding the nonlinear propagation of DIA solitary waves in laboratory and space plasmas.

Computation of the spectrum of spatial Lyapunov exponents for the spatially extended beam-plasma systems and electron-wave devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hramov, Alexander E.; Saratov State Technical University, Politechnicheskaja str., 77, Saratov 410054; Koronovskii, Alexey A.

2012-08-15

The spectrum of Lyapunov exponents is powerful tool for the analysis of the complex system dynamics. In the general framework of nonlinear dynamics, a number of the numerical techniques have been developed to obtain the spectrum of Lyapunov exponents for the complex temporal behavior of the systems with a few degree of freedom. Unfortunately, these methods cannot be applied directly to analysis of complex spatio-temporal dynamics of plasma devices which are characterized by the infinite phase space, since they are the spatially extended active media. In the present paper, we propose the method for the calculation of the spectrum ofmore » the spatial Lyapunov exponents (SLEs) for the spatially extended beam-plasma systems. The calculation technique is applied to the analysis of chaotic spatio-temporal oscillations in three different beam-plasma model: (1) simple plasma Pierce diode, (2) coupled Pierce diodes, and (3) electron-wave system with backward electromagnetic wave. We find an excellent agreement between the system dynamics and the behavior of the spectrum of the spatial Lyapunov exponents. Along with the proposed method, the possible problems of SLEs calculation are also discussed. It is shown that for the wide class of the spatially extended systems, the set of quantities included in the system state for SLEs calculation can be reduced using the appropriate feature of the plasma systems.« less

Measurement of the electron beam mode in earth's foreshock

NASA Technical Reports Server (NTRS)

Onsager, T. G.; Holzworth, R. H.

1990-01-01

High frequency electric field measurements from the AMPTE IRM plasma wave receiver are used to identify three simultaneously excited electrostatic wave modes in the earth's foreshock region: the electron beam mode, the Langmuir mode, and the ion acoustic mode. A technique is developed which allows the rest frame frequecy and wave number of the electron beam waves to be determined. It is shown that the experimentally determined rest frame frequency and wave number agree well with the most unstable frequency and wave number predicted by linear homogeneous Vlasov theory for a plasma with Maxwellian background electrons and a Lorentzian electron beam. From a comparison of the experimentally determined and theoretical values, approximate limits are put on the electron foreshock beam temperatures. A possible generation mechanism for ion acoustic waves involving mode coupling between the electron beam and Langmuir modes is also discussed.

Propagation of cylindrical ion acoustic waves in a plasma with q-nonextensive electrons with nonthermal distribution

NASA Astrophysics Data System (ADS)

El-Depsy, A.; Selim, M. M.

2016-12-01

The propagation of ion acoustic waves (IAWs) in a cylindrical collisionless unmagnetized plasma, containing ions and electrons is investigated. The electrons are considered to be nonextensive and follow nonthermal distribution. The reductive perturbation technique (RPT) is used to obtain a nonlinear cylindrical Kadomtsev-Petviashvili (CKP) evolution equation. This equation is solved analytically. The effects of plasma parameters on the IAWs characteristics are discussed in details. Both compressive and rarefactive solitons are found to be created in the proposed plasma system. The profile of IAWs is found to depend on the nonextensive and nonthermal parameters. The present study is useful for understanding IAWs in the regions where mixed electron distribution in space, or laboratory plasmas, exist.

Effects of group velocity and multiplasmon resonances on the modulation of Langmuir waves in a degenerate plasma

NASA Astrophysics Data System (ADS)

Misra, Amar P.; Chatterjee, Debjani; Brodin, Gert

2017-11-01

We study the nonlinear wave modulation of Langmuir waves (LWs) in a fully degenerate plasma. Using the Wigner-Moyal equation coupled to the Poisson equation and the multiple scale expansion technique, a modified nonlocal nonlinear Schrödinger (NLS) equation is derived which governs the evolution of LW envelopes in degenerate plasmas. The nonlocal nonlinearity in the NLS equation appears due to the group velocity and multiplasmon resonances, i.e., resonances induced by the simultaneous particle absorption of multiple wave quanta. We focus on the regime where the resonant velocity of electrons is larger than the Fermi velocity and thereby the linear Landau damping is forbidden. As a result, the nonlinear wave-particle resonances due to the group velocity and multiplasmon processes are the dominant mechanisms for wave-particle interaction. It is found that in contrast to classical or semiclassical plasmas, the group velocity resonance does not necessarily give rise the wave damping in the strong quantum regime where ℏ k ˜m vF with ℏ denoting the reduced Planck's constant, m the electron mass, and vF the Fermi velocity; however, the three-plasmon process plays a dominant role in the nonlinear Landau damping of wave envelopes. In this regime, the decay rate of the wave amplitude is also found to be higher compared to that in the modest quantum regime where the multiplasmon effects are forbidden.

Polarization resolved electric field measurements on plasma bullets in N2 using four-wave mixing

NASA Astrophysics Data System (ADS)

van der Schans, Marc; Boehm, Patrick; Nijdam, Sander; Ijzerman, Wilbert; Czarnetzki, Uwe

2016-09-01

Atmospheric pressure plasma jets generated by kHz AC or pulsed DC voltages typically consist of discrete guided ionization waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated using the four-wave mixing method. In this diagnostic two laser beams, where one is Stokes shifted from the other, non-linearly interact with the N2 molecules and the bullet's electric field. As a result of the interaction a coherent anti-Stokes Raman scattered (CARS) beam and an infrared beam are generated from which the electric field can be determined. Compared to emission-based methods, this technique has the advantage of being able to also probe the electric field in regions around the plasma bullet where no photons are emitted. The four-wave mixing method and its analysis have been adapted to work with the non-uniform electric field of plasma bullets. In addition, an ex-situ calibration procedure using an electrode geometry different from the discharge geometry has been developed. An experimentally obtained radial profile of the axial electric field component of a plasma bullet in N2 is presented. The position of this profile is related to the location of the propagating bullet from temporally resolved images.

Modification of ordinary-mode reflectometry system to detect lower-hybrid waves in Alcator C-Mod

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baek, S. G.; Shiraiwa, S.; Parker, R. R.

2012-10-15

Backscattering experiments to detect lower-hybrid (LH) waves have been performed in Alcator C-Mod, using the two modified channels (60 GHz and 75 GHz) of an ordinary-mode reflectometry system with newly developed spectral recorders that can continuously monitor spectral power at a target frequency. The change in the baseline of the spectral recorder during the LH wave injection is highly correlated to the strength of the X-mode non-thermal electron cyclotron emission. In high density plasmas where an anomalous drop in the lower hybrid current drive efficiency is observed, the observed backscattered signals are expected to be generated near the last closedmore » flux surface, demonstrating the presence of LH waves within the plasma. This experimental technique can be useful in identifying spatially localized LH electric fields in the periphery of high-density plasmas.« less

Using ion flows parallel and perpendicular to gravity to modify dust acoustic waves

NASA Astrophysics Data System (ADS)

Thomas, E.; Fisher, R.

2008-11-01

Recent studies of dust acoustic waves have shown that the dust kinetic temperature can play an important role in determining the resulting dispersion relation [M. Rosenberg, et al., Phys. Plasmas, 15, 073701 (2008)]. In these studies, it is believed that ion flows play a dominant role in determining both the kinetic temperature of the charged microparticles as well as providing the source of energy for triggering the waves. In this presentation, results will be presented on the effects of ion flow on spatial structure and velocity distribution of dust acoustic waves. Here, the waves will be formed in dusty plasmas consisting of 3 ± 1 micron diameter silica microspheres. Two separate electrodes will be used to modify the ion flow in the plasma -- one parallel to the direction of gravity and one perpendicular to the direction of gravity. Particle image velocimetry (PIV) techniques will be used to observe the particles and to measure their velocity distributions.

Feasibility study for using an extended three-wave model to simulate plasma-based backward Raman amplification in one spatial dimension

NASA Astrophysics Data System (ADS)

Wang, T.-L.; Michta, D.; Lindberg, R. R.; Charman, A. E.; Martins, S. F.; Wurtele, J. S.

2009-12-01

Results are reported of a one-dimensional simulation study comparing the modeling capability of a recently formulated extended three-wave model [R. R. Lindberg, A. E. Charman, and J. S. Wurtele, Phys. Plasmas 14, 122103 (2007); Phys. Plasmas 15, 055911 (2008)] to that of a particle-in-cell (PIC) code, as well as to a more conventional three-wave model, in the context of the plasma-based backward Raman amplification (PBRA) [G. Shvets, N. J. Fisch, A. Pukhov et al., Phys. Rev. Lett. 81, 4879 (1998); V. M. Malkin, G. Shvets, and N. J. Fisch, Phys. Rev. Lett. 82, 4448 (1999); Phys. Rev. Lett. 84, 1208 (2000)]. The extended three-wave model performs essentially as well as or better than a conventional three-wave description in all temperature regimes tested, and significantly better at the higher temperatures studied, while the computational savings afforded by the extended three-wave model make it a potentially attractive tool that can be used prior to or in conjunction with PIC simulations to model the kinetic effects of PBRA for nonrelativistic laser pulses interacting with underdense thermal plasmas. Very fast but reasonably accurate at moderate plasma temperatures, this model may be used to perform wide-ranging parameter scans or other exploratory analyses quickly and efficiently, in order to guide subsequent simulation via more accurate if intensive PIC techniques or other algorithms approximating the full Vlasov-Maxwell equations.

Application of Atmospheric-Pressure Microwave Line Plasma for Low Temperature Process

NASA Astrophysics Data System (ADS)

Suzuki, Haruka; Nakano, Suguru; Itoh, Hitoshi; Sekine, Makoto; Hori, Masaru; Toyoda, Hirotaka

2015-09-01

Atmospheric pressure (AP) plasmas have been given much attention because of its high cost benefit and a variety of possibilities for industrial applications. In various kinds of plasma production technique, pulsed-microwave discharge plasma using slot antenna is attractive due to its ability of high-density and stable plasma production. In this plasma source, however, size of the plasma has been limited up to a few cm in length due to standing wave inside a waveguide. To solve this, we have proposed a newly-developed AP microwave plasma source that utilizes not standing wave but travelling wave. By using this plasma source, spatially-uniform AP line plasma with 40 cm in length was realized by pure helium discharge in 60 cm slot and with nitrogen gas additive of 1%. Furthermore, gas temperature as low as 400 K was realized in this device. In this study, as an example of low temperature processes, hydrophilic treatment of PET films was performed. Processing speed increased with pulse frequency and a water contact angle of ~20° was easily obtained within 5 s with no thermal damage to the substrate. To evaluate treatment-uniformity of long line length, PET films were treated by 90 cm slot-antenna plasma and uniform treatment performance was confirmed.

Nonlinear dust-lattice waves: a modified Toda lattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cramer, N. F.

Charged dust grains in a plasma interact with a Coulomb potential, but also with an exponential component to the potential, due to Debye shielding in the background plasma. Here we investigate large-amplitude oscillations and waves in dust-lattices, employing techniques used in Toda lattice analysis. The lattice consists of a linear chain of particles, or a periodic ring as occurs in experimentally observed dust particle clusters. The particle motion has a triangular waveform, and chaotic motion for large amplitude motion of a grain.

The Tea-Carbon Dioxide Laser as a Means of Generating Ultrasound in Solids

NASA Astrophysics Data System (ADS)

Taylor, Gregory Stuart

1990-01-01

Available from UMI in association with The British Library. Requires signed TDF. The aim of this thesis is to characterise the interaction between pulsed, high power, 10.6 mu m radiation and solids. The work is considered both in the general context of laser generation of ultrasound and specifically to gain a deeper understanding of the interaction between a laser supported plasma and a solid. The predominant experimental tools used are the homodyne Michelson interferometer and a range of electromagnetic acoustic transducers. To complement the ultrasonic data, various plasma inspection techniques, such as high speed, streak camera photography and reflection photometry, have been used to correlate the plasma properties with those of the ultrasonic transients. The work involving the characterisation of a laser supported plasma with a solid, which is based on previous experimental and theoretical analysis, gives an increased understanding of the plasma's ultrasonic generation mechanism. The ability to record the entire plasma-sample interaction, time history yields information of the internal dynamics of the plasma growth and shock wave generation. The interaction of the radiation with a solid is characterised in both the plasma breakdown and non-breakdown regimes by a wide ultrasonic source. The variation in source diameter enables the transition from a point to a near planar ultrasonic source to be studied. The resultant ultrasonic modifications are examined in terms of the wave structure and the directivity pattern. The wave structure is analysed in terms of existing wide source, bulk wave theories and extended to consider the effects on surface and Lamb waves. The directivity patterns of the longitudinal and shear waves are analysed in terms of top-hat and non -uniform source profiles, giving additional information into the radiation-solid interaction. The wide, one dimensional source analysis is continued to a two dimensional, extended ultrasonic source, generated on non-metals by the optical penetration of radiation within the target. The generation of ultrasound in both metals and non-metals, using the CO_2 laser, is shown to be an efficient process and may be employed almost totally non-destructively. Such a laser may therefore be used effectively on a greatly enhanced range of materials than those tested to-date via laser generation, resulting in the increased suitability of the laser technique within the field of Non Destructive Testing.

Electric field determination in the plasma-antenna boundary of a lower-hybrid wave launcher in Tore Supra through dynamic Stark-effect spectroscopy

DOE PAGES

Martin, Elijah H.; Goniche, M.; Klepper, C. Christopher; ...

2015-04-22

Interaction of radio-frequency (RF) waves with the plasma in the near-field of a high-power wave launcher is now seen to be important, both in understanding the channeling of these waves through the plasma boundary and in avoiding power losses in the edge. In a recent Letter a direct non-intrusive measurement of a near antenna RF electric field in the range of lower hybrid (LH) frequencies (more » $$E_{LH}$$) was announced (Phys. Rev. Lett., 110:215005, 2013). The measurement was achieved through the fitting of Balmer series deuterium spectral lines utilizing a time dependent (dynamic) Stark effect model. In this article, the processing of the spectral data is discussed in detail and applied to a larger range of measurements and the accuracy and limitations of the experimental technique is investigated. We find through an analysis of numerous Tore Supra pulses that good quantitative agreement exists between the measured and full-wave modeled $$E_{LH}$$ when the launched power exceeds 0.5MW. For low power the measurement becomes formidable utilizing the implemented passive spectroscopic technique because the spectral noise overwhelms the effect of the RF electric field on the line profile. Additionally, effects of the ponderomotive force are suspected at sufficiently high power.« less

Description of the plasma diagnostics package (PDP) for the OSS-1 Shuttle mission and JSC plasma chamber test in conjunction with the fast pulse electron gun (FPEG)

NASA Technical Reports Server (NTRS)

Shawhan, S. D.

1982-01-01

The objectives, equipment, and techniques for the plasma diagnostics package (PDP) carried by the OSS-1 instrument payload of the STS-4 and scheduled for the Spacelab-2 mission are described. The goals of the first flight were to examine the Orbiter-magnetoplasma interactions by measuring the electric and magnetic field strengths, the ionized particle wakes, and the generated waves. The RMS was employed to lift the unit out of the bay in order to allow characterization of the fields, EM interference, and plasma contamination within 15 m of the Orbiter. The PDP will also be used to examine plasma depletion, chemical reaction rates, waves, and energized plasma produced by firing of the Orbiter thrusters. Operation of the PDP was carried out in the NASA Space Environment Simulation Laboratory test chamber, where the PDP was used to assay the fields, fluxes, wave amplitudes, and particle energy spectra. The PDP instrumentation is also capable of detecting thermal ions, thermal electrons suprathermal particles, VHF/UHF EMI levels, and the S-band field strength.

Waveguide to Core: A New Approach to RF Modelling

NASA Astrophysics Data System (ADS)

Wright, John; Shiraiwa, Syunichi; Rf-Scidac Team

2017-10-01

A new technique for the calculation of RF waves in toroidal geometry enables the simultaneous incorporation of antenna geometry, plasma facing components (PFCs), the scrape off-layer (SOL) and core propagation [Shiraiwa, NF 2017]. Calculations with this technique naturally capture wave propagation in the SOL and its interactions with non-conforming PFCs permitting self-consistent calculation of core absorption and edge power loss. The main motivating insight is that the core plasma region having closed flux surfaces requires a hot plasma dielectric while the open field line region in the scrape-off layer needs only a cold plasma dielectric. Spectral approaches work well for the former and finite elements work well for the latter. The validity of this process follows directly from the superposition principle of Maxwell's equations making this technique exact. The method is independent of the codes or representations used and works for any frequency regime. Applications to minority heating in Alcator C-Mod and ITER and high harmonic heating in NSTX-U will be presented in single pass and multi-pass regimes. Support from DoE Grant Number DE-FG02-91-ER54109 (theory and computer resources) and DE-FC02-01ER54648 (RF SciDAC).

A Comparison of Laser Induced Florescence and Continuous Wave Ring Down Spectroscopy Measurements of Argon Ion and Neutral VDFs in a Helicon Plasma

NASA Astrophysics Data System (ADS)

McCarren, Dustin; Vandervort, Robert; Carr, Jerry, Jr.; Scime, Earl

2012-10-01

In this work, we compare two spectroscopic methods for measuring the velocity distribution functions (VDFs) of argon ions and neutrals in a helicon plasma: laser induced florescence (LIF) and continuous wave cavity ring down spectroscopy (CW-CRDS). An established and powerful technique, LIF suffers from the requirement that the initial state of the LIF sequence have a substantial density. In most cases, this requirement limits LIF to ions and atoms with large metastable state densities for the given plasma conditions. CW-CRDS is considerably more sensitive than LIF and can potentially be applied to much lower density populations of ion and atom states. However, CRDS is a line integrated technique that lacks the spatial resolution of LIF. CRDS is a proven, ultra-sensitive, cavity enhanced absorption spectroscopy technique and when combined with a CW diode laser that has a sufficiently narrow linewidth, the Doppler broadened absorption line, i.e., the VDFs, can be measured. We present CW-CRDS and LIF measurements of the VDFs in an argon plasma using the 668.614 nm (in vacuum) line of Ar II and the 667.9125 nm (in vacuum) line of Ar I.

Dust Acoustic Solitary Waves in Dusty Plasma with Trapped Electrons Having Different Temperature Nonthermal Ions

NASA Astrophysics Data System (ADS)

Deka, Manoj Kr.

2016-12-01

In this report, a detailed investigation on the study of dust acoustics solitary waves solution with negatively dust charge fluctuation in dusty plasma corresponding to lower and higher temperature nonthermal ions with trapped electrons is presented. We consider temporal variation of dust charge as a source of dissipation term to derive the lower order modified Kadomtsev-Petviashvili equation by using the reductive perturbation technique. Solitary wave solution is obtained with the help of sech method in presence of trapped electrons and low (and high) temperature nonthermal ions. Both nonthermality of ions and trapped state of the electrons are found to have an imperative control on the nonlinear coefficient, dissipative coefficient as well as height of the wave potential.

Nonplanar ion acoustic waves with kappa-distributed electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahu, Biswajit

2011-06-15

Using the standard reductive perturbation technique, nonlinear cylindrical and spherical Kadomtsev-Petviashvili equations are derived for the propagation of ion acoustic solitary waves in an unmagnetized collisionless plasma with kappa distributed electrons and warm ions. The influence of kappa-distributed electrons and the effects caused by the transverse perturbation on cylindrical and spherical ion acoustic waves (IAWs) are investigated. It is observed that increase in the kappa distributed electrons (i.e., decreasing {kappa}) decreases the amplitude of the solitary electrostatic potential structures. The numerical results are presented to understand the formation of ion acoustic solitary waves with kappa-distributed electrons in nonplanar geometry. Themore » present investigation may have relevance in the study of propagation of IAWs in space and laboratory plasmas.« less

Kinetic-scale fluctuations resolved with the Fast Plasma Investigation on NASA's Magnetospheric Multiscale mission.

NASA Astrophysics Data System (ADS)

Gershman, D. J.; Figueroa-Vinas, A.; Dorelli, J.; Goldstein, M. L.; Shuster, J. R.; Avanov, L. A.; Boardsen, S. A.; Stawarz, J. E.; Schwartz, S. J.; Schiff, C.; Lavraud, B.; Saito, Y.; Paterson, W. R.; Giles, B. L.; Pollock, C. J.; Strangeway, R. J.; Russell, C. T.; Torbert, R. B.; Moore, T. E.; Burch, J. L.

2017-12-01

Measurements from the Fast Plasma Investigation (FPI) on NASA's Magnetospheric Multiscale (MMS) mission have enabled unprecedented analyses of kinetic-scale plasma physics. FPI regularly provides estimates of current density and pressure gradients of sufficient accuracy to evaluate the relative contribution of terms in plasma equations of motion. In addition, high-resolution three-dimensional velocity distribution functions of both ions and electrons provide new insights into kinetic-scale processes. As an example, for a monochromatic kinetic Alfven wave (KAW) we find non-zero, but out-of-phase parallel current density and electric field fluctuations, providing direct confirmation of the conservative energy exchange between the wave field and particles. In addition, we use fluctuations in current density and magnetic field to calculate the perpendicular and parallel wavelengths of the KAW. Furthermore, examination of the electron velocity distribution inside the KAW reveals a population of electrons non-linearly trapped in the kinetic-scale magnetic mirror formed between successive wave peaks. These electrons not only contribute to the wave's parallel electric field but also account for over half of the density fluctuations within the wave, supplying an unexpected mechanism for maintaining quasi-neutrality in a KAW. Finally, we demonstrate that the employed wave vector determination technique is also applicable to broadband fluctuations found in Earth's turbulent magnetosheath.

Gas-filled capillaries for plasma-based accelerators

NASA Astrophysics Data System (ADS)

Filippi, F.; Anania, M. P.; Brentegani, E.; Biagioni, A.; Cianchi, A.; Chiadroni, E.; Ferrario, M.; Pompili, R.; Romeo, S.; Zigler, A.

2017-07-01

Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented.

Drift Wave Chaos and Turbulence in a LAPTAG Plasma Physics experiment

NASA Astrophysics Data System (ADS)

Katz, Cami; Gekelman, Walter; Pribyl, Patrick; Wise, Joe; Birge-Lee, Henry; Baker, Bob; Marmie, Ken; Thomas, Sam; Buckley-Bonnano, Samuel

2015-11-01

Whenever there is a pressure gradient in a magnetized plasma drift waves occur spontaneously. Drift waves have density and electrical potential fluctuations but no self magnetic field. In our experiment the drift waves form spontaneously in a narrow plasma column. (ne = 5 ×1011 cm3 , Te = 5 eV , B = 200 Gauss, dia = 25 cm , L = 1 . 5 m). As the drift waves grow from noise simple averaging techniques cannot be used to map them out in space and time. The ion saturation current Isat n√{Te} is recorded for an ensemble of 50 shots on a fixed probe located on the density gradient and for a movable probe. The probe signals are not sinusoidal and are filtered to calculate the cross-spectral function CSF = ∫ ∑ nshot Ifix, ωr->1 , tImov , ω (r->1 + δr-> , t + τ) dt , which can be used to extract the temporal and spatially varying wave patterns. The dominant wave at 18 kHz is a rotating spiral with m =2. LAPTAG is a university-high school alliance outreach program, which has been in existence for over 20 years. Work done at the BaPSF and supported by NSF/DOE.

Cylindrical ion-acoustic solitary waves in electronegative plasmas with superthermal electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eslami, Parvin; Mottaghizadeh, Marzieh

2012-06-15

By using the standard reductive perturbation technique, a three-dimensional cylindrical Kadomtsev-Petviashvili equation (CKPE), which governs the dynamics of ion acoustic solitary waves (IASWs), is derived for small but finite amplitude ion-acoustic waves in cylindrical geometry in a collisionless unmagnetized plasma with kappa distributed electrons, thermal positrons, and cold ions. The generalized expansion method is used to solve analytically the CKPE. The existence regions of localized pulses are investigated. It is found that the solution of the CKPE supports only compressive solitary waves. Furthermore, the effects of superthermal electrons, the ratio of the electron temperature to positron temperature, the ratio ofmore » the positron density to electron density and direction cosine of the wave propagation on the profiles of the amplitudes, and widths of the solitary structures are examined numerically. It is shown these parameters play a vital role in the formation of ion acoustic solitary waves.« less

Ion acoustic waves at comet 67P/Churyumov-Gerasimenko. Observations and computations

NASA Astrophysics Data System (ADS)

Gunell, H.; Nilsson, H.; Hamrin, M.; Eriksson, A.; Odelstad, E.; Maggiolo, R.; Henri, P.; Vallieres, X.; Altwegg, K.; Tzou, C.-Y.; Rubin, M.; Glassmeier, K.-H.; Stenberg Wieser, G.; Simon Wedlund, C.; De Keyser, J.; Dhooghe, F.; Cessateur, G.; Gibbons, A.

2017-04-01

Context. On 20 January 2015 the Rosetta spacecraft was at a heliocentric distance of 2.5 AU, accompanying comet 67P/Churyumov-Gerasimenko on its journey toward the Sun. The Ion Composition Analyser (RPC-ICA), other instruments of the Rosetta Plasma Consortium, and the ROSINA instrument made observations relevant to the generation of plasma waves in the cometary environment. Aims: Observations of plasma waves by the Rosetta Plasma Consortium Langmuir probe (RPC-LAP) can be explained by dispersion relations calculated based on measurements of ions by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA), and this gives insight into the relationship between plasma phenomena and the neutral coma, which is observed by the Comet Pressure Sensor of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument (ROSINA-COPS). Methods: We use the simple pole expansion technique to compute dispersion relations for waves on ion timescales based on the observed ion distribution functions. These dispersion relations are then compared to the waves that are observed. Data from the instruments RPC-LAP, RPC-ICA and the mutual impedance probe (RPC-MIP) are compared to find the best estimate of the plasma density. Results: We find that ion acoustic waves are present in the plasma at comet 67P/Churyumov-Gerasimenko, where the major ion species is H2O+. The bulk of the ion distribution is cold, kBTI = 0.01 eV when the ion acoustic waves are observed. At times when the neutral density is high, ions are heated through acceleration by the solar wind electric field and scattered in collisions with the neutrals. This process heats the ions to about 1 eV, which leads to significant damping of the ion acoustic waves. Conclusions: In conclusion, we show that ion acoustic waves appear in the H2O+ plasmas at comet 67P/Churyumov-Gerasimenko and how the interaction between the neutral and ion populations affects the wave properties. Computer code for the dispersion analysis is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/600/A3

Dynamic Response of a Magnetized Plasma to AN External Source: Application to Space and Solid State Plasmas

NASA Astrophysics Data System (ADS)

Zhou, Huai-Bei

This dissertation examines the dynamic response of a magnetoplasma to an external time-dependent current source. To achieve this goal a new method which combines analytic and numerical techniques to study the dynamic response of a 3-D magnetoplasma to a time-dependent current source imposed across the magnetic field was developed. The set of the cold electron and/or ion plasma equations and Maxwell's equations are first solved analytically in (k, omega)^ace; inverse Laplace and 3 -D complex Fast Fourier Transform (FFT) techniques are subsequently used to numerically transform the radiation fields and plasma currents from the (k, omega) ^ace to the (r, t) space. The dynamic responses of the electron plasma and of the compensated two-component plasma to external current sources are studied separately. The results show that the electron plasma responds to a time -varying current source imposed across the magnetic field by exciting whistler/helicon waves and forming of an expanding local current loop, induced by field aligned plasma currents. The current loop consists of two anti-parallel field-aligned current channels concentrated at the ends of the imposed current and a cross-field current region connecting these channels. The latter is driven by an electron Hall drift. A compensated two-component plasma responds to the same current source as following: (a) For slow time scales tau > Omega_sp{i}{-1} , it generates Alfven waves and forms a non-local current loop in which the ion polarization currents dominate the cross-field current; (b) For fast time scales tau < Omega_sp{i}{-1} , the dynamic response of the compensated two-component plasma is the same as that of the electron plasma. The characteristics of the current closure region are determined by the background plasma density, the magnetic field and the time scale of the current source. This study has applications to a diverse range of space and solid state plasma problems. These problems include current closure in emf inducing tethered satellite systems (TSS), generation of ELF/VLF waves by ionospheric heating, current closure and quasineutrality in thin magnetopause transitions, and short electromagnetic pulse generation in solid state plasmas. The cross-field current in TSS builds up on a time scale corresponding to the whistler waves and results in local current closure. Amplitude modulated HF ionospheric heating generates ELF/VLF waves by forming a horizontal magnetic dipole. The dipole is formed by the current closure in the modified region. For thin transition the time-dependent cross-field polarization field at the magnetopause could be neutralized by the formation of field aligned current loops that close by a cross-field electron Hall current. A moving current source in a solid state plasma results in microwave emission if the speed of the source exceeds the local phase velocity of the helicon or Alfven waves. Detailed analysis of the above problems is presented in the thesis.

Modulated heavy nucleus-acoustic waves and associated rogue waves in a degenerate relativistic quantum plasma system

NASA Astrophysics Data System (ADS)

Sultana, S.; Islam, S.; Mamun, A. A.; Schlickeiser, R.

2018-01-01

A theoretical and numerical investigation has been carried out on amplitude modulated heavy nucleus-acoustic envelope solitons (HNAESs) in a degenerate relativistic quantum plasma (DRQP) system containing relativistically degenerate electrons and light nuclei, and non-degenerate mobile heavy nuclei. The cubic nonlinear Schrödinger equation, describing the nonlinear dynamics of the heavy nucleus-acoustic waves (HNAWs), is derived by employing a multi-scale perturbation technique. The dispersion relation for the HNAWs is derived, and the criteria for the occurrence of modulational instability of the HNAESs are analyzed. The localized structures (viz., envelope solitons and associated rogue waves) are found to be formed in the DRQP system under consideration. The basic features of the amplitude modulated HNAESs and associated rogue waves formed in realistic DRQP systems are briefly discussed.

Lower hybrid accessibility in a large, hot reversed field pinch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dziubek, R.A.

1995-02-01

Recent theoretical and experimental results indicate that driving a current in the outer radius of an RPF suppresses sawtooth activity and increases particle and energy confinement times. One candidate for a form of steady state current drive is the slow wave at the lower hybrid frequency. Here, the accessibility of such a wave in an RFP plasma is investigated theoretically, with focus on the RFX machine of Padua, Italy. To drive current, the slow wave with frequency between 1.0--1.5 GHz is considered where optimal Landau damping is desired at r/a {approximately} 0.7. By numerically determining the values of the wave`smore » perpendicular index of refraction which satisfy the hot plasma dispersion relation, regions of propagation and evanescence can be found. The path of the wave can then be traced over a contour map of these regions so that accessibility can be clearly seen. The possibility of mode conversion events can be ascertained by plotting the values of the perpendicular index of refraction for the fast and slow wave and observing convergence points. To locate regions of maximum Landau damping, a technique developed by Stix was adapted for use with the slow wave in an RFP plasma. Results show that the slow wave is accessible to the target region without mode conversion so long as the value of the parallel index of refraction is correctly chosen at the edge of the plasma. Landau damping can also be optimized with this method. In an RFP, 2--20% of the electron population consists of fast electrons. Because this species alters the total electron distribution function and raises the effective temperature in the outer regions of the plasma, its presence is expected to shift the location of ideal Landau damping.« less

Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

NASA Technical Reports Server (NTRS)

Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

2008-01-01

Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

Perturbed soliton excitations of Rao-dust Alfvén waves in magnetized dusty plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kavitha, L., E-mail: louiskavitha@yahoo.co.in; The Abdus Salam International Centre for Theoretical Physics, Trieste; Lavanya, C.

We investigate the propagation dynamics of the perturbed soliton excitations in a three component fully ionized dusty magnetoplasma consisting of electrons, ions, and heavy charged dust particulates. We derive the governing equation of motion for the two dimensional Rao-dust magnetohydrodynamic (R-D-MHD) wave by employing the inertialess electron equation of motion, inertial ion equation of motion, the continuity equations in a plasma with immobile charged dust grains, together with the Maxwell's equations, by assuming quasi neutrality and neglecting the displacement current in Ampere's law. Furthermore, we assume the massive dust particles are practically immobile since we are interested in timescales muchmore » shorter than the dusty plasma period, thereby neglecting any damping of the modes due to the grain charge fluctuations. We invoke the reductive perturbation method to represent the governing dynamics by a perturbed cubic nonlinear Schrödinger (pCNLS) equation. We solve the pCNLS, along the lines of Kodama-Ablowitz multiple scale nonlinear perturbation technique and explored the R-D-MHD waves as solitary wave excitations in a magnetized dusty plasma. Since Alfvén waves play an important role in energy transport in driving field-aligned currents, particle acceleration and heating, solar flares, and the solar wind, this representation of R-D-MHD waves as soliton excitations may have extensive applications to study the lower part of the earth's ionosphere.« less

Influence of the distance between target surface and focal point on the expansion dynamics of a laser-induced silicon plasma with spatial confinement

NASA Astrophysics Data System (ADS)

Zhang, Dan; Chen, Anmin; Wang, Xiaowei; Wang, Ying; Sui, Laizhi; Ke, Da; Li, Suyu; Jiang, Yuanfei; Jin, Mingxing

2018-05-01

Expansion dynamics of a laser-induced plasma plume, with spatial confinement, for various distances between the target surface and focal point were studied by the fast photography technique. A silicon wafer was ablated to induce the plasma with a Nd:YAG laser in an atmospheric environment. The expansion dynamics of the plasma plume depended on the distance between the target surface and focal point. In addition, spatially confined time-resolved images showed the different structures of the plasma plumes at different distances between the target surface and focal point. By analyzing the plume images, the optimal distance for emission enhancement was found to be approximately 6 mm away from the geometrical focus using a 10 cm focal length lens. This optimized distance resulted in the strongest compression ratio of the plasma plume by the reflected shock wave. Furthermore, the duration of the interaction between the reflected shock wave and the plasma plume was also prolonged.

Dust Ion-Acoustic Shock Waves in a Multicomponent Magnetorotating Plasma

NASA Astrophysics Data System (ADS)

Kaur, Barjinder; Saini, N. S.

2018-02-01

The nonlinear properties of dust ion-acoustic (DIA) shock waves in a magnetorotating plasma consisting of inertial ions, nonextensive electrons and positrons, and immobile negatively charged dust are examined. The effects of dust charge fluctuations are not included in the present investigation, but the ion kinematic viscosity (collisions) is a source of dissipation, leading to the formation of stable shock structures. The Zakharov-Kuznetsov-Burgers (ZKB) equation is derived using the reductive perturbation technique, and from its solution the effects of different physical parameters, i.e. nonextensivity of electrons and positrons, kinematic viscosity, rotational frequency, and positron and dust concentrations, on the characteristics of shock waves are examined. It is observed that physical parameters play a very crucial role in the formation of DIA shocks. This study could be useful in understanding the electrostatic excitations in dusty plasmas in space (e.g. interstellar medium).

Self-consistent theory for the linear and nonlinear propagation of a sinusoidal electron plasma wave. Application to stimulated Raman scattering in a non-uniform and non-stationary plasma

NASA Astrophysics Data System (ADS)

Bénisti, Didier

2018-01-01

In this paper, we address the theoretical resolution of the Vlasov-Gauss system from the linear regime to the strongly nonlinear one, when significant trapping has occurred. The electric field is that of a sinusoidal electron plasma wave (EPW) which is assumed to grow from the noise level, and to keep growing at least up to the amplitude when linear theory in no longer valid (while the wave evolution in the nonlinear regime may be arbitrary). The ions are considered as a neutralizing fluid, while the electron response to the wave is derived by matching two different techniques. We make use of a perturbation analysis similar to that introduced to prove the Kolmogorov-Arnold-Moser theorem, up to amplitudes large enough for neo-adiabatic results to be valid. Our theory is applied to the growth and saturation of the beam-plasma instability, and to the three-dimensional propagation of a driven EPW in a non-uniform and non-stationary plasma. For the latter example, we lay a special emphasis on nonlinear collisionless dissipation. We provide an explicit theoretical expression for the nonlinear Landau-like damping rate which, in some instances, is amenable to a simple analytic formula. We also insist on the irreversible evolution of the electron distribution function, which is nonlocal in the wave amplitude and phase velocity. This makes trapping an effective means of dissipation for the electrostatic energy, and also makes the wave dispersion relation nonlocal. Our theory is generalized to allow for stimulated Raman scattering, which we address up to saturation by accounting for plasma inhomogeneity and non-stationarity, nonlinear kinetic effects, and interspeckle coupling.

Ion heating and short wavelength fluctuations in a helicon plasma source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scime, E. E.; Carr, J. Jr.; Galante, M.

2013-03-15

For typical helicon source parameters, the driving antenna can couple to two plasma modes; the weakly damped 'helicon' wave, and the strongly damped, short wavelength, slow wave. Here, we present direct measurements, obtained with two different techniques, of few hundred kHz, short wavelength fluctuations that are parametrically driven by the primary antenna and localized to the edge of the plasma. The short wavelength fluctuations appear for plasma source parameters such that the driving frequency is approximately equal to the lower hybrid frequency. Measurements of the steady-state ion temperature and fluctuation amplitude radial profiles suggest that the anomalously high ion temperaturesmore » observed at the edge of helicon sources result from damping of the short wavelength fluctuations. Additional measurements of the time evolution of the ion temperature and fluctuation profiles in pulsed helicon source plasmas support the same conclusion.« less

Collaborative Research: Tomographic imaging of laser-plasma structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Downer, Michael

The interaction of intense short laser pulses with ionized gases, or plasmas, underlies many applications such as acceleration of elementary particles, production of energy by laser fusion, generation of x-ray and far-infrared “terahertz” pulses for medical and materials probing, remote sensing of explosives and pollutants, and generation of guide stars. Such laser-plasma interactions create tiny electron density structures (analogous to the wake behind a boat) inside the plasma in the shape of waves, bubbles and filaments that move at the speed of light, and evolve as they propagate. Prior to recent work by the PI of this proposal, detailed knowledgemore » of such structures came exclusively from intensive computer simulations. Now “snapshots” of these elusive, light-velocity structures can be taken in the laboratory using dynamic variant of holography, the technique used to produce ID cards and DVDs, and dynamic variant of tomography, the technique used in medicine to image internal bodily organs. These fast visualization techniques are important for understanding, improving and scaling the above-mentioned applications of laser-plasma interactions. In this project, we accomplished three things: 1) We took holographic pictures of a laser-driven plasma-wave in the act of accelerating electrons to high energy, and used computer simulations to understand the pictures. 2) Using results from this experiment to optimize the performance of the accelerator, and the brightness of x-rays that it emits. These x-rays will be useful for medical and materials science applications. 3) We made technical improvements to the holographic technique that enables us to see finer details in the recorded pictures. Four refereed journal papers were published, and two students earned PhDs and moved on to scientific careers in US National Laboratories based on their work under this project.« less

Plasma production for electron acceleration by resonant plasma wave

NASA Astrophysics Data System (ADS)

Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Di Pirro, G. P.; Filippi, F.; Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R.; Romeo, S.; Ferrario, M.

2016-09-01

Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10-100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.

Visualization by discharge illumination technique and modification by plasma actuator of rarefied Mach 2 airflow around a cylinder

NASA Astrophysics Data System (ADS)

Leger, L.; Sellam, M.; Barbosa, E.; Depussay, E.

2013-06-01

The use of plasma actuators for flow control has received considerable attention in recent years. This kind of device seems to be an appropriate means of raising abilities in flow control thanks to total electric control, no moving parts and a fast response time. The experimental work presented here shows, firstly, the non-intrusive character of the visualization of the density field of an airflow around a cylinder obtained using a plasma luminescence technique. Experiments are made in a continuous supersonic wind tunnel. The static pressure in the flow is 8 Pa, the mean free path is about 0.3 mm and the airflow velocity is 510 m s-1. Pressure measurements obtained by means of glass Pitot tube without the visualization discharge are proposed. Measured and simulated pressure profiles are in good agreement in the region near the cylinder. There is good correlation between numerical simulations of the supersonic flow field, analytical model predictions and experimental flow visualizations obtained by a plasma luminescence technique. Consequently, we show that the plasma luminescence technique is non-intrusive. Secondly, the effect of a dc discharge on a supersonic rarefied air flow around a cylinder is studied. An electrode is flush mounted on the cylinder. Stagnation pressure profiles are examined for different electrode positions on the cylinder. A shock wave modification depending on the electrode location is observed. The discharge placed at the upstream stagnation point induces an upstream shift of the bow shock, whereas a modification of the shock wave shape is observed when it is placed at 45° or 90°.

Analytical investigation of microwave resonances of a curling probe for low and high-pressure plasma diagnostics

NASA Astrophysics Data System (ADS)

Arshadi, Ali; Brinkmann, Ralf Peter

2017-01-01

The concept of ‘active plasma resonance spectroscopy’ (APRS) has attracted greater interest in recent years as an established plasma diagnostic technique. The APRS describes a class of related methods utilizing the intrinsic ability of plasma to resonate at or near the electron plasma frequency {ω\\text{pe}} . The Curling probe (CP) as a novel realization of the APRS idea, is a miniaturized spiral slot embedded flatly in the chamber wall. Consequently, a plasma diagnostic technique with minimum disturbance and without metal contamination can be developed. To measure the plasma parameters the CP is fed with a weak frequency-swept signal from the exterior of the plasma chamber by a network analyzer which also records the response of the plasma versus the frequency. The resonance behavior is strongly dependent on the electron density and the gas pressure. The CP has also the advantage of resonating at a frequency greater than {ω\\text{pe}} which is dependent on the spiral’s length. The double resonance characteristic gives the CP the ability to be applied in varying plasma regimes. Assuming that the spiralization does not have a considerable effect on the resonances, a ‘straightened’ infinite length CP has recently been investigated (Arshadi and Brinkmann 2016 Plasma Sources Sci. Technol. 25 045014) to obtain the surface wave resonances. This work generalizes the approach and models the CP by a rectangular slot-type resonator located between plasma and quartz. Cold plasma theory and Maxwell’s equations are utilized to compute the electromagnetic fields propagating into the plasma by the diffraction of an incident plane wave at the slot. A mathematical model is employed and both kinds of resonances are derived. The analytical study of this paper shows good agreement with the numerical results of the probe inventors.

An unambiguous determination of the propagation of a compressional Pc 5 wave

NASA Technical Reports Server (NTRS)

Lin, N.; Mcpherron, R. L.; Kivelson, M. G.; Williams, D. J.

1988-01-01

A compressional Pc5 event observed by the ISEE-1 magnetometer and Medium Energetic Particle Experiment instrument on August 21 and 22, 1978, is examined. The propagation properties of the compressional waves were determined using a technique which utilizes the finite Larmor radius effects in the signature of the multichannel energetic ion detector. It is shown that this technique determines unambiguously the propagation characteristics of the wave in both the azimuthal and the radial directions in the plane perpendicular to the background magnetic field; the results remained valid even though heavy energetic ions with Larmor radii larger than proton Larmor radii were present in the plasma.

An unambiguous determination of the propagation of a compressional Pc 5 wave

NASA Astrophysics Data System (ADS)

Lin, N.; McPherron, R. L.; Kivelson, M. G.; Williams, D. J.

1988-06-01

A compressional Pc5 event observed by the ISEE-1 magnetometer and Medium Energetic Particle Experiment instrument on August 21 and 22, 1978, is examined. The propagation properties of the compressional waves were determined using a technique which utilizes the finite Larmor radius effects in the signature of the multichannel energetic ion detector. It is shown that this technique determines unambiguously the propagation characteristics of the wave in both the azimuthal and the radial directions in the plane perpendicular to the background magnetic field; the results remained valid even though heavy energetic ions with Larmor radii larger than proton Larmor radii were present in the plasma.

ITER Plasma at Ion Cyclotron Frequency Domain: The Fusion Alpha Particles Diagnostics Based on the Stimulated Raman Scattering of Fast Magnetosonic Wave off High Harmonic Ion Bernstein Modes

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander

2014-10-01

A novel method for alpha particle diagnostics is proposed. The theory of stimulated Raman scattering, SRS, of the fast wave and ion Bernstein mode, IBM, turbulence in multi-ion species plasmas, (Stefan University Press, La Jolla, CA, 2008). is utilized for the diagnostics of fast ions, (4)He (+2), in ITER plasmas. Nonlinear Landau damping of the IBM on fast ions near the plasma edge leads to the space-time changes in the turbulence level, (inverse alpha particle channeling). The space-time monitoring of the IBM turbulence via the SRS techniques may prove efficient for the real time study of the fast ion velocity distribution function, spatial distribution, and transport. Supported by Nikola Tesla Labs., La Jolla, CA 92037.

The development of the miniaturized waveform receiver with the function measuring Antenna Impedance in space plasmas

NASA Astrophysics Data System (ADS)

Ishii, H.; Kojima, H.; Fukuhara, H.; Okada, S.; Yamakawa, H.

2012-04-01

Plasma wave is one of the most essential physical quantities in the solar terrestrial physics. The role of plasma wave receiver onboard satellites is to detect plasma waves in space with a good signal to noise ratio. There are two types of plasma wave receivers, the sweep frequency analyzer and the waveform capture. While the sweep frequency analyzer provides plasma wave spectra, the waveform capture obtains waveforms with phase information that is significant in studying nonlinear phenomena. Antenna sensors to observe electric fields of the plasma waves show different features in plasmas from in vacuum. The antenna impedances have specific characteristics in the frequency domain because of the dispersion of plasmas. These antenna impedances are expressed with complex number. We need to know not only the antenna impedances but also the transfer functions of plasma wave receiver's circuits in order to calibrate observed waveforms precisely. The impedances of the electric field antennas are affected by a state of surrounding plasmas. Since satellites run through various regions with different plasma parameters, we precisely should measure the antenna impedances onboard spacecraft. On the contrary, we can obtain the plasma density and by measuring the antenna impedances. Several formulas of the antenna impedance measurement system were proposed. A synchronous detection method is used on the BepiColombo Mercury Magnetospheric Orbiter (MMO), which will be launched in 2014. The digital data are stored in the onboard memory. They are read out and converted to the analog waveforms by D/A converter. They are fed into the input of the preamplifiers of antenna sensors through a resistor. We can calculate a transfer function of the circuit by applying the synchronous detection method to the output waveform from waveform receivers and digital data as a signal source. The size of this system is same as an A5 board. In recent years, Application Specific Integrated Circuit (ASIC) is in attention which is a technique to integrate large scale and complicated circuits. Lots of ASICs have been applied to high energy astrophysics. In this paper, we show our attempt to miniaturize the antennas impedances measurement system and Waveform Capture using the analogue ASIC. We design 8bits segment D/A converter that is implemented inside the waveform receiver ASIC chip. We improve input logic of the D/A converter to generate very weak signals accurately. The designed chip realizes the measurement of the antenna impedance as well as the waveform observation in the board size of business cards.

On performance of cylindrical dipole antenna in diagnostics of wave phenomena in space plasma

NASA Astrophysics Data System (ADS)

Kiraga, A.

Tubular and wire antennas have been employed since an advent of in situ measurements in space. It is generally accepted that they are well suited to recipe electromagnetic radiation from remote sources as well as divers local plasma emissions. Quasi thermal noise spectroscopy provides an example of well documented, both experimentally and theoretically, technique to study solar wind plasma. In many data sets of wave spectra, recorded with use of tubular or wire antennas at all altitudes inside a plasma sphere, there is pronounced, permanent, variable frequency spectral structure, routinely assigned to upper hybrid band (UHR) emissions. On the other hand, spectral structure, which could be assigned to upper hybrid band, is less pronounced and infrequent, in sets of wave spectra recorded in polar region with the use of spherical double probes. These apparently inconsistent observations have not drawn much attention of wave community. Assignment to UHR emission have been bolstered by theoretical plausibility, permanency in data sets, frequency verification with independent techniques and conviction that measurements were performed with good voltmeter with well known properties. It has been recognized that stray capacitance acts as a voltage divider and underestimates real voltage imposed on antenna. But in sufficiently dense and cold main plasma component, even short antenna is inductive in some frequency band below upper hybrid frequency. Stray capacitance and antenna inductance result in circuit resonance, which is very pronounced, if antenna resistance is low and input resistance is high. In such circumstances, a good voltmeter concept is very misleading. In this report we show that good voltmeter concept is not sufficient for interpretation of passive mode spectra recorded with tubular antenna on IK -19, APEX and CORONAS satellites. With orbit inclination of ~80deg and altitude range of 500-3000km, very divers plasmas were encountered, but distinct plasma emission within upper hybrid band do not show up. In equivalent circuit simulations, salient spectral characteristics can be matched and related to specific impedances. Equivalent circuit analysis was enforced by apparent difference between local plasma frequencies derived from onboard topside sounder data and frequencies of adjacent maximum in passive mode spectra. It has been subsequently verified and developed with the aid of impedance measurements, onboard sounder data and analysis of electron beam induced spectra. We show that circuit resonance can be neatly controlled to provide very low interference technique to monitor density of cold plasma. Circuit resonance monitoring, if properly coupled with impedance measurements and electron beam injection may be very useful, low interference tool for diagnostics of highly structured plasmas like those in auroral region.

X-ray Imaging and preliminary studies of the X-ray self-emission from an innovative plasma-trap based on the Bernstein waves heating mechanism

NASA Astrophysics Data System (ADS)

Caliri, C.; Romano, F. P.; Mascali, D.; Gammino, S.; Musumarra, A.; Castro, G.; Celona, L.; Neri, L.; Altana, C.

2013-10-01

Electron Cyclotron Resonance Ion Sources (ECRIS) are based on ECR heated plasmas emitting high fluxes of X-rays. Here we illustrate a pilot study of the X-ray emission from a compact plasma-trap in which an off-resonance microwave-plasma interaction has been attempted, highlighting a possible Bernstein-Waves based heating mechanism. EBWs-heating is obtained via the inner plasma EM-to-ES wave conversion and enables to reach densities much larger than the cut-off ones. At LNS-INFN, an innovative diagnostic technique based on the design of a Pinhole Camera (PHC) coupled to a CCD device for X-ray Imaging of the plasma (XRI) has been developed, in order to integrate X-ray traditional diagnostics (XRS). The complementary use of electrostatic probes measurements and X-ray diagnostics enabled us to gain knowledge about the high energy electrons density and temperature and about the spatial structure of the source. The combination of the experimental data with appropriate modeling of the plasma-source allowed to estimate the X-ray emission intensity in different energy domains (ranging from EUV up to Hard X-rays). The use of ECRIS as X-ray source for multidisciplinary applications, is now a concrete perspective due to the intense fluxes produced by the new plasma heating mechanism.

Comparative In Situ Measurements of Plasma Instabilities in the Equatorial and Auroral Electrojets

NASA Technical Reports Server (NTRS)

Pfaff, Robert F.

2008-01-01

This presentation provides a comparison of in situ measurements of plasma instabilities gathered by rocket-borne probes in the equatorial and auroral electrojets. Specifically, using detailed measurements of the DC electric fields, current density, and plasma number density within the unstable daytime equatorial electrojet from Brazil (Guara Campaign) and in the auroral electrojet from Sweden (ERRIS Campaign), we present comparative observations and general conclusions regarding the observed physical properties of Farley-Buneman two-stream waves and large scale, gradient drift waves. The two stream observations reveal coherent-like waves propagating near the E x B direction but at reduced speeds (nearer to the presumed acoustic velocity) with wavelengths of approximately 5-10m in both the equatorial and auroral electrojet, as measured using the spaced-receiver technique. The auroral electrojet data generally shows extensions to shorter wavelengths, in concert with the fact that these waves are driven harder. With respect to gradient-drift driven waves, observations of this instability are much more pronounced in the equatorial electrojet, given the more favorable geometry for growth provided by the vertical gradient and horizontal magnetic field lines. We present new analysis of Guara rocket observations of electric field and plasma density data that reveal considerable structuring in the middle and lower portion of the electrojet (90-105 km) where the ambient plasma density gradient is unstable. Although the electric field amplitudes are largest (approximately 10-15 mV/m) in the zonal direction, considerable structure (approximately 5-10 mV/m) is also observed in the vertical electric field component as well, implying that the dominant large scale waves involve significant vertical interaction and coupling within the narrow altitude range where they are observed. Furthermore, a detailed examination of the phase of the waveforms show that on some, but not all occasions, locally enhanced eastward fields are associated with locally enhanced upwards (polarization) electric fields. The measurements are discussed in terms of theories involving the non-linear evolution and structuring of plasma waves.

An experimental study of turbulence by phase-contrast imaging in the DIII-D tokamak

NASA Astrophysics Data System (ADS)

Coda, Stefano

1997-10-01

A CO2-laser imaging system employing the Zernike phase-contrast technique was designed, built, installed, and operated on the DIII-D tokamak. This system measures the line integrals of plasma density fluctuations along 16 vertical chords at the outer edge of the tokamak (0.85

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark C.

We use a two-dimensional laser-induced fluorescence spectroscopy technique to measure the coupled absorption and emission properties of atomic species in plasmas produced via laser ablation of solid aluminum targets at atmospheric pressure. Emission spectra from the Al I 394.4 nm and Al I 396.15 nm transitions are measured while a frequency-doubled, continuous-wave, Ti:Sapphire laser is tuned across the Al I 396.15 nm transition. The resulting two-dimensional spectra show the energy coupling between the two transitions via increased emission intensity for both transitions during resonant absorption of the continuous-wave laser at one transition. Time-delayed and gated detection of the emission spectrummore » is used to isolate the resonantly-excited fluorescence emission from the thermally-excited emission from the plasma. In addition, the tunable continuous-wave laser measures the absorption spectrum of the Al transition with ultra-high resolution after the plasma has cooled, resulting in narrower spectral linewidths than observed in emission spectra. Our results highlight that fluorescence spectroscopy employing continuous-wave laser re-excitation after pulsed laser ablation combines benefits of both traditional emission and absorption spectroscopic methods.« less

Case study of inclined sporadic E layers in the Earth's ionosphere observed by CHAMP/GPS radio occultations: Coupling between the tilted plasma layers and internal waves

NASA Astrophysics Data System (ADS)

Gubenko, Vladimir N.; Pavelyev, A. G.; Kirillovich, I. A.; Liou, Y.-A.

2018-04-01

We have used the radio occultation (RO) satellite data CHAMP/GPS (Challenging Minisatellite Payload/Global Positioning System) for studying the ionosphere of the Earth. A method for deriving the parameters of ionospheric structures is based upon an analysis of the RO signal variations in the phase path and intensity. This method allows one to estimate the spatial displacement of a plasma layer with respect to the ray perigee, and to determine the layer inclination and height correction values. In this paper, we focus on the case study of inclined sporadic E (Es) layers in the high-latitude ionosphere based on available CHAMP RO data. Assuming that the internal gravity waves (IGWs) with the phase-fronts parallel to the ionization layer surfaces are responsible for the tilt angles of sporadic plasma layers, we have developed a new technique for determining the parameters of IGWs linked with the inclined Es structures. A small-scale internal wave may be modulating initially horizontal Es layer in height and causing a direction of the plasma density gradient to be rotated and aligned with that of the wave propagation vector k. The results of determination of the intrinsic wave frequency and period, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase speeds, and other characteristics of IGWs under study are presented and discussed.

Long-Range Transhorizon Lunar Surface Radio Wave Propagation in the Presence of a Regolith and a Sparse Exospheric Plasma

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2008-01-01

Long-range, over-the-horizon (transhorizon) radio wave propagation is considered for the case of the Moon. In the event that relay satellites are not available or otherwise unwarranted for use, transhorizon communication provides for a contingency or backup option for non line-of-sight lunar surface exploration scenarios. Two potential low-frequency propagation mechanisms characteristic of the lunar landscape are the lunar regolith and the photoelectron induced plasma exosphere enveloping the Moon. Although it was hoped that the regolith would provide for a spherical waveguide which could support a trapped surface wave phenomena, it is found that, in most cases, the regolith is deleterious to long range radio wave propagation. However, the presence of the plasma of the lunar exosphere supports wave propagation and, in fact, surpasses the attenuation of the regolith. Given the models of the regolith and exosphere adopted here, it is recommended that a frequency of 1 MHz be considered for low rate data transmission along the lunar surface. It is also recommended that further research be done to capture the descriptive physics of the regolith and the exospheric plasma so that a more complete model can be obtained. This comprehensive theoretical study is based entirely on first principles and the mathematical techniques needed are developed as required; it is self-contained and should not require the use of outside resources for its understanding.

Application of the shaped electrode technique to a large area rectangular capacitively coupled plasma reactor to suppress standing wave nonuniformity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sansonnens, L.; Schmidt, H.; Howling, A.A.

The electromagnetic standing wave effect can become the main source of nonuniformity limiting the use of very high frequency in large area reactors exceeding 1 m{sup 2} required for industrial applications. Recently, it has been proposed and shown experimentally in a cylindrical reactor that a shaped electrode in place of the conventional flat electrode can be used in order to suppress the electromagnetic standing wave nonuniformity. In this study, we show experimental measurements demonstrating that the shaped electrode technique can also be applied in large area rectangular reactors. We also present results of electromagnetic screening by a conducting substrate whichmore » has important consequences for industrial application of the shaped electrode technique.« less

Head-on collision between positron acoustic waves in homogeneous and inhomogeneous plasmas

NASA Astrophysics Data System (ADS)

Alam, M. S.; Hafez, M. G.; Talukder, M. R.; Ali, M. Hossain

2018-05-01

The head-on collision between positron acoustic solitary waves (PASWs) as well as the production of rogue waves (RWs) in homogeneous and PASWs in inhomogeneous unmagnetized plasma systems are investigated deriving the nonlinear evolution equations. The plasmas are composed of immobile positive ions, mobile cold and hot positrons, and hot electrons, where the hot positrons and hot electrons are assumed to follow the Kappa distributions. The evolution equations are derived using the appropriate coordinate transformation and the reductive perturbation technique. The effects of concentrations, kappa parameters of hot electrons and positrons, and temperature ratios on the characteristics of PASWs and RWs are examined. It is found that the kappa parameters and temperature ratios significantly modify phase shifts after head-on collisions and RWs in homogeneous as well as PASWs in inhomogeneous plasmas. The amplitudes of the PASWs in inhomogeneous plasmas are diminished with increasing kappa parameters, concentration and temperature ratios. Further, the amplitudes of RWs are reduced with increasing charged particles concentration, while it enhances with increasing kappa- and temperature parameters. Besides, the compressive and rarefactive solitons are produced at critical densities from KdV equation for hot and cold positrons, while the compressive solitons are only produced from mKdV equation for both in homogeneous and inhomogeneous plasmas.

Synthesis of Pt nanoparticles as catalysts of oxygen reduction with microbubble-assisted low-voltage and low-frequency solution plasma processing

NASA Astrophysics Data System (ADS)

Horiguchi, Genki; Chikaoka, Yu; Shiroishi, Hidenobu; Kosaka, Shinpei; Saito, Morihiro; Kameta, Naohiro; Matsuda, Naoki

2018-04-01

In the preparation of metallic nanoparticles by conventional solution plasma (SP) techniques, unstable plasma emission becomes an issue when the voltage and frequency of the waves applied between two electrodes placed in solution are lowered to avoid the boiling of the solution. In this study, we confirm that, in the presence of microbubbles, plasma is generated stably at low voltage (440 V) and low frequency (50-100 Hz) and small-size (≤10 nm) Pt nanoparticles (PtNPs) are synthesized in succession using a flow cell. The smallest PtNPs, ∼3.3 nm in diameter, are obtained using half-wave rectification, a tungsten wire anode, and a platinum wire cathode. The PtNPs are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimeter-differential thermal analysis. The oxygen reduction reaction (ORR) is investigated in 0.1 M HClO4 solution on carbon-supported PtNPs using a rotating ring-disk electrode. The catalytic activities per initial electrochemical active surface area of the carbon-supported PtNPs synthesized employing the low-voltage, low-frequency (LVLF)-SP technique is higher than that of the commercially available 20 wt% Pt on Vulcan XC-72R. These results indicate that the LVLF-SP technique is a promising approach to producing carbon-supported PtNPs that catalyze ORR with low energy consumption.

Fundamentals of Plasma Physics

NASA Astrophysics Data System (ADS)

Bellan, Paul M.

2008-07-01

Preface; 1. Basic concepts; 2. The Vlasov, two-fluid, and MHD models of plasma dynamics; 3. Motion of a single plasma particle; 4. Elementary plasma waves; 5. Streaming instabilities and the Landau problem; 6. Cold plasma waves in a magnetized plasma; 7. Waves in inhomogeneous plasmas and wave energy relations; 8. Vlasov theory of warm electrostatic waves in a magnetized plasma; 9. MHD equilibria; 10. Stability of static MHD equilibria; 11. Magnetic helicity interpreted and Woltjer-Taylor relaxation; 12. Magnetic reconnection; 13. Fokker-Planck theory of collisions; 14. Wave-particle nonlinearities; 15. Wave-wave nonlinearities; 16. Non-neutral plasmas; 17. Dusty plasmas; Appendix A. Intuitive method for vector calculus identities; Appendix B. Vector calculus in orthogonal curvilinear coordinates; Appendix C. Frequently used physical constants and formulae; Bibliography; References; Index.

Incoherent Scatter Plasma Lines: Observations and Applications

NASA Astrophysics Data System (ADS)

Akbari, Hassanali; Bhatt, Asti; La Hoz, Cesar; Semeter, Joshua L.

2017-10-01

Space plasmas are host to the electrostatic Langmuir waves and a rich range of processes associated with them. Many of such processes that are of interest in micro-scale plasma physics and magnetosphere-ionosphere physics are open to investigation via incoherent scatter plasma lines—i.e., a pair of resonant peaks in the incoherent scatter radar (ISR) spectrum, symmetrically displaced from the radar transmitting frequency by about the plasma frequency, as the signature of Langmuir waves in the ISR spectrum. There now exists a large body of literature devoted to the investigation of a number of topics in ionospheric physics via plasma line theory and observation. It is the goal of this work to provide a comprehensive review of this literature, from the early theoretical works on oscillations in magnetized plasma to the recent advances in plasma line measurements and applications. This review includes detailed theoretical discussions on the intensity and frequency displacement of plasma lines. It reviews the experimental observations of plasma lines enhanced by various sources of energy and discusses the implications of the observations in the context of ionospheric physics. The review also covers the practical aspects of plasma line measurements, from measurement techniques to the applications of plasma lines in estimating the bulk parameters of the ionosphere.

Observations of strong ion-ion correlations in dense plasmas

DOE PAGES

Ma, T.; Fletcher, L.; Pak, A.; ...

2014-04-24

Using simultaneous spectrally, angularly, and temporally resolved x-ray scattering, we measure the pronounced ion-ion correlation peak in a strongly coupled plasma. Laser-driven shock-compressed aluminum at ~3× solid density is probed with high-energy photons at 17.9 keV created by molybdenum He-α emission in a laser-driven plasma source. The measured elastic scattering feature shows a well-pronounced correlation peak at a wave vector of k=4Å –1. The magnitude of this correlation peak cannot be described by standard plasma theories employing a linear screened Coulomb potential. Advanced models, including a strong short-range repulsion due to the inner structure of the aluminum ions are howevermore » in good agreement with the scattering data. These studies have demonstrated a new highly accurate diagnostic technique to directly measure the state of compression and the ion-ion correlations. Furthermore, we have since applied this new method in single-shot wave-number resolved S(k) measurements to characterize the physical properties of dense plasmas.« less

Nonlinear mixing of electromagnetic waves in plasmas.

PubMed

Stefan, V; Cohen, B I; Joshi, C

1989-01-27

Recently, a strong research effort has been focused on applications of beat waves in plasma interactions. This research has important implications for various aspects of plasma physics and plasma technology. This article reviews the present status of the field and comments on plasma probing, heating of magnetically confined and laser plasmas, ionospheric plasma modification, beat-wave particle acceleration, beat-wave current drive in toroidal devices, beat wave-driven free-electron lasers, and phase conjugation with beat waves.

Longitudinal terahertz wave generation from an air plasma filament induced by a femtosecond laser

NASA Astrophysics Data System (ADS)

Minami, Yasuo; Kurihara, Takayuki; Yamaguchi, Keita; Nakajima, Makoto; Suemoto, Tohru

2013-04-01

We have generated and detected a longitudinally polarized (Z-polarized) terahertz (THz) wave by focusing a conically propagating THz beam generated from a plasma filament induced by a femtosecond laser pulse. In the experiment, we observed a radially polarized field in a collimated region and Z-polarized field at focus in the time domain. The maximum value of the Z-polarized THz electric field reached 1.0 kV/cm. It was also quantitatively discussed about the Z-polarized field and the radial field at the focal point. We expect this technique to find application in THz time domain spectroscopy.

Physics of the inner heliosphere 1-10R sub O plasma diagnostics and models

NASA Technical Reports Server (NTRS)

Withbroe, G. L.

1984-01-01

The physics of solar wind flow in the acceleration region and impulsive phenomena in the solar corona is studied. The study of magnetohydrodynamic wave propagation in the corona and the solutions for steady state and time dependent solar wind equations gives insights concerning the physics of the solar wind acceleration region, plasma heating and plasma acceleration processes and the formation of shocks. Also studied is the development of techniques for placing constraints on the mechanisms responsible for coronal heating.

Four-Spacecraft Magnetic Curvature and Vorticity Analyses on Kelvin-Helmholtz Waves in MHD Simulations

NASA Astrophysics Data System (ADS)

Kieokaew, Rungployphan; Foullon, Claire; Lavraud, Benoit

2018-01-01

Four-spacecraft missions are probing the Earth's magnetospheric environment with high potential for revealing spatial and temporal scales of a variety of in situ phenomena. The techniques allowed by these four spacecraft include the calculation of vorticity and the magnetic curvature analysis (MCA), both of which have been used in the study of various plasma structures. Motivated by curved magnetic field and vortical structures induced by Kelvin- Helmholtz (KH) waves, we investigate the robustness of the MCA and vorticity techniques when increasing (regular) tetrahedron sizes, to interpret real data. Here for the first time, we test both techniques on a 2.5-D MHD simulation of KH waves at the magnetopause. We investigate, in particular, the curvature and flow vorticity across KH vortices and produce time series for static spacecraft in the boundary layers. The combined results of magnetic curvature and vorticity further help us to understand the development of KH waves. In particular, first, in the trailing edge, the magnetic curvature across the magnetopause points in opposite directions, in the wave propagation direction on the magnetosheath side and against it on the magnetospheric side. Second, the existence of a "turnover layer" in the magnetospheric side, defined by negative vorticity for the duskside magnetopause, which persists in the saturation phase, is reminiscent of roll-up history. We found significant variations in the MCA measures depending on the size of the tetrahedron. This study lends support for cross-scale observations to better understand the nature of curvature and its role in plasma phenomena.

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

PubMed

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.

From core to coax: extending core RF modelling to include SOL, Antenna, and PFC

NASA Astrophysics Data System (ADS)

Shiraiwa, Syun'ichi

2017-10-01

A new technique for the calculation of RF waves in toroidal geometry enables the simultaneous incorporation of antenna geometry, plasma facing components (PFCs), the scrape off-layer (SOL), and core propagation. Traditionally, core RF wave propagation and antenna coupling has been calculated separately both using rather simplified SOL plasmas. The new approach, instead, allows capturing wave propagation in the SOL and its interactions with non-conforming PFCs permitting self-consistent calculation of core absorption and edge power loss, as well as investigating far and near field impurity generation from RF sheaths and a breakdown issue from antenna electric fields. Our approach combines the field solutions obtained from a core spectral code with a hot plasma dielectric and an edge FEM code using a cold plasma approximation via surface admittance-like matrix. Our approach was verified using the TORIC core ICRF spectral code and the commercial COMSOL FEM package, and was extended to 3D torus using open-source scalable MFEM library. The simulation result revealed that as the core wave damping gets weaker, the wave absorption in edge could become non-negligible. Three dimensional capabilities with non axisymmetric edge are being applied to study the antenna characteristic difference between the field aligned and toroidally aligned antennas on Alcator C-Mod, as well as the surface wave excitation on NSTX-U. Work supported by the U.S. DoE, OFES, using User Facility Alcator C-Mod, DE-FC02-99ER54512 and Contract No. DE-FC02-01ER54648.

Propagation of high frequency electrostatic surface waves along the planar interface between plasma and dusty plasma

NASA Astrophysics Data System (ADS)

Mishra, Rinku; Dey, M.

2018-04-01

An analytical model is developed that explains the propagation of a high frequency electrostatic surface wave along the interface of a plasma system where semi-infinite electron-ion plasma is interfaced with semi-infinite dusty plasma. The model emphasizes that the source of such high frequency waves is inherent in the presence of ion acoustic and dust ion acoustic/dust acoustic volume waves in electron-ion plasma and dusty plasma region. Wave dispersion relation is obtained for two distinct cases and the role of plasma parameters on wave dispersion is analyzed in short and long wavelength limits. The normalized surface wave frequency is seen to grow linearly for lower wave number but becomes constant for higher wave numbers in both the cases. It is observed that the normalized frequency depends on ion plasma frequencies when dust oscillation frequency is neglected.

Generation of whistler waves by continuous HF heating of the upper ionosphere

NASA Astrophysics Data System (ADS)

Vartanyan, A.; Milikh, G. M.; Eliasson, B. E.; Sharma, A.; Chang, C.; Parrot, M.; Papadopoulos, K.

2013-12-01

We report observations of VLF waves by the DEMETER satellite overflying the HAARP facility during ionospheric heating experiments. The detected VLF waves were in the range 8-17 kHz and coincided with times of continuous heating. The experiments indicate whistler generation due to conversion of artificial lower hybrid waves to whistlers on small scale field-aligned plasma density striations. The observations are compared with theoretical models, taking into account both linear and nonlinear processes. Implications of the mode conversion technique on VLF generation with subsequent injection into the radiation belts to trigger particle precipitation are discussed.

Electromagnetic radiation and nonlinear energy flow in an electron beam-plasma system

NASA Technical Reports Server (NTRS)

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

1985-01-01

It is shown that the unstable electron-plasma waves of a beam-plasma system can generate electromagnetic radiation in a uniform plasma. The generation mechanism is a scattering of the unstable electron plasma waves off ion-acoustic waves, producing electromagnetic waves whose frequency is near the local plasma frequency. The wave vector and frequency matching conditions of the three-wave mode coupling are experimentally verified. The electromagnetic radiation is observed to be polarized with the electric field parallel to the beam direction, and its source region is shown to be localized to the unstable plasma wave region. The frequency spectrum shows negligible intensity near the second harmonic of the plasma frequency. These results suggest that the observed electromagnetic radiation of type III solar bursts may be generated near the local plasma frequency and observed downstream where the wave frequency is near the harmonic of the plasma frequency.

Middle Atmosphere Program. Handbook for MAP, volume 19

NASA Technical Reports Server (NTRS)

Goldberg, R. A. (Editor)

1986-01-01

This MAP handbook is concerned with rocket techniques and instrumentation as they are currently employed in the middle atmosphere. It is composed of nine chapters, written by experts on rocket experiments. The emphasis is on measurement techniques rather than results, although results are incorporated wherever they provide examples which illustrate the measurement features. The chapters first cover techniques relating to measurements of neutral dynamics and chemistry, then measurements of the various intermittent and excessive radiation sources which effect the middle atmospheric environment, and finally measurements of the plasma environment including electric fields. The weighting toward plasma related parameters is not accidental, but reflects both the historical headstart given by early development of radio wave and probe techniques to measure electron density, and by the relatively limited number of techniques available for neutral atmospheric measurements.

Plasma current start-up experiments without the central solenoid in the TST-2 spherical tokamak

NASA Astrophysics Data System (ADS)

Takase, Y.; Ejiri, A.; Shiraiwa, S.; Adachi, Y.; Ishii, N.; Kasahara, H.; Nuga, H.; Ono, Y.; Oosako, T.; Sasaki, M.; Shimada, Y.; Sumitomo, N.; Taguchi, I.; Tojo, H.; Tsujimura, J.; Ushigome, M.; Yamada, T.; Hanada, K.; Hasegawa, M.; Idei, H.; Nakamura, K.; Sakamoto, M.; Sasaki, K.; Sato, K. N.; Zushi, H.; Nishino, N.; Mitarai, O.

2006-08-01

Several techniques for initiating the plasma current without the use of the central solenoid are being developed in TST-2. While TST-2 was temporarily located at Kyushu University, two types of start-up scenarios were demonstrated. (1) A plasma current of 4 kA was generated and sustained for 0.28 s by either electron cyclotron wave or electron Bernstein wave, without induction. (2) A plasma current of 10 kA was obtained transiently by induction using only outboard poloidal field coils. In the second scenario, it is important to supply sufficient power for ionization (100 kW of EC power was sufficient in this case), since the vertical field during start-up is not adequate to maintain plasma equilibrium. In addition, electron heating experiments using the X-B mode conversion scenario were performed, and a heating efficiency of 60% was observed at a 100 kW RF power level. TST-2 is now located at the Kashiwa Campus of the University of Tokyo. Significant upgrades were made in both magnetic coil power supplies and RF systems, and plasma experiments have restarted. RF power of up to 400 kW is available in the high-harmonic fast wave frequency range around 20 MHz. Four 200 MHz transmitters are now being prepared for plasma current start-up experiments using RF power in the lower-hybrid frequency range. Preparations are in progress for a new plasma merging experiment (UTST) aimed at the formation and sustainment of ultra-high β ST plasmas.

Threshold for plasma phase transition of aluminum single crystal induced by hypervelocity impact

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ju, Yuanyuan; Zhang, Qingming, E-mail: qmzhang@bit.edu.cn

2015-12-15

Molecular dynamics method is used to study the threshold for plasma phase transition of aluminum single crystal induced by hypervelocity impact. Two effective simulation methods, piston-driven method and multi-scale shock technique, are used to simulate the shock wave. The simulation results from the two methods agree well with the experimental data, indicating that the shock wave velocity is linearly dependent on the particle velocity. The atom is considered to be ionized if the increase of its internal energy is larger than the first ionization energy. The critical impact velocity for plasma phase transition is about 13.0 km/s, corresponding to the thresholdmore » of pressure and temperature which is about 220 GPa and 11.0 × 10{sup 3 }K on the shock Hugoniot, respectively.« less

Theory of Electromagnetic Surface Waves in Plasma with Smooth Boundaries

NASA Astrophysics Data System (ADS)

Kuzelev, M. V.

2018-05-01

A theory of nonpotential surface waves in plasma with smooth boundaries is developed. The complex frequencies of surface waves for plasma systems of different geometries and different profiles of the plasma density are calculated. Expressions for the rates of collisionless damping of surface waves due to their resonance interaction with local plasma waves of continuous spectrum are obtained. The influence of collisions in plasma is also considered.

Planetary plasma waves

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

1993-01-01

The primary types of plasma waves observed in the vicinity of the planets Venus, Mars, Earth, Jupiter, Saturn, Uranus, and Neptune are described. The observations are organized according to the various types of plasma waves observed, ordered according to decreasing distance from the planet, starting from the sunward side of the planet, and ending in the region near the closest approach. The plasma waves observed include: electron plasma oscillations and ion acoustic waves; trapped continuum radiation; electron cyclotron and upper hybrid waves; whistler-mode emissions; electrostatic ion cyclotron waves; and electromagnetic ion cyclotron waves.

Imaging of spatial distributions of the millimeter wave intensity by using the Visible Continuum Radiation from a discharge in a Cs-Xe mixture. Part II: Demonstration of application capabilities of the technique

NASA Astrophysics Data System (ADS)

Gitlin, M. S.; Glyavin, M. Yu.; Fedotov, A. E.; Tsvetkov, A. I.

2017-07-01

The paper presents the second part of the review on a high-sensitive technique for time-resolved imaging and measurements of the 2D intensity profiles of millimeter-wave radiation by means of Visible Continuum Radiation emitted by the positive column of a medium-pressure Cs-Xe DC Discharge (VCRD method). The first part of the review was focused on the operating principles and fundamentals of this new technique [Plasma Phys. Rep. 43, 253 (2017)]. The second part of the review focuses on experiments demonstrating application of this imaging technique to measure the parameters of radiation at the output of moderate-power millimeter-wave sources. In particular, the output waveguide mode of a moderate-power W-band gyrotron with a pulsed magnetic field was identified and the relative powers of some spurious modes at the outputs of this gyrotron and a pulsed D-band orotron were evaluated. The paper also reviews applications of the VCRD technique for real-time imaging and nondestructive testing with a frame rate of higher than 10 fps by using millimeter waves. Shadow projection images of objects opaque and transparent for millimeter waves have been obtained using pulsed watt-scale millimeter waves for object illumination. Near video frame rate millimeter-wave shadowgraphy has been demonstrated. It is shown that this technique can be used for single-shot screening (including detection of concealed objects) and time-resolved imaging of time-dependent processes.

Non-Linear Dynamics and Emergence in Laboratory Fusion Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hnat, B.

2011-09-22

Turbulent behaviour of laboratory fusion plasma system is modelled using extended Hasegawa-Wakatani equations. The model is solved numerically using finite difference techniques. We discuss non-linear effects in such a system in the presence of the micro-instabilities, specifically a drift wave instability. We explore particle dynamics in different range of parameters and show that the transport changes from diffusive to non-diffusive when large directional flows are developed.

Millimeter wave generation by relativistic electron beams

NASA Astrophysics Data System (ADS)

Kuo, S. S.; Cheo, B. R.; Tiong, K. K.; Whang, M. H.

1985-11-01

The classical technique of transformation and characteristics is employed to analyze the problem of strong turbulence in unmagnetized plasmas. The effects of resonance broadening and perturbation expansion are treated simultaneously without time securities. The renormalization procedure is used in the transformed Vlasov equation to analyze the turbulence and to derive explicitly a diffusion equation. Analyses are extended to imhomogeneous plasma and the relationship between the transformation and ponderomotive force is obtained.

Direct Determination of Wavenumbers of ULF Waves Using the Cluster Multipoint and Multicomponent Measurements

NASA Astrophysics Data System (ADS)

Grison, B.; Escoubet, C.; Santolik, O.; Cornilleau-Wehrlin, N.

2013-12-01

The wavenumber is a key parameter to understand the physics of the interactions between the electromagnetic waves and the ionized particles in space plasmas. Search-coil magnetometers and electric antennas measure time series of both magnetic and electric field fluctuations, respectively. The fleet of four Cluster spacecraft made possible to determine the full wave vector and even to differentiate the waves present at the same frequency in the spacecraft frame through various techniques: k-filtering analysis, wave telescope, phase differentiating method. However the fleet configuration (inter-spacecraft separation, tetrahedron elongation and planarity) limit the possibilities to use these techniques. From single spacecraft measurements, assumptions concerning the wave mode -and thus, concerning the physical processes- are usually required to derive the corresponding wavenumber. Using three orthogonal magnetic components and two electric antennas, it is possible to estimate n/Z where n is the refractive index and Z the transfer function of the interface between the plasma and the electric antennas. For ULF waves we assume Z=1 and we thus obtain the wavenumber. We test this hypothesis on a case where the spacecraft are in a close configuration in the distant cusp region and where we are able to apply the k-filtering analysis, too. The results obtained by multispacecraft and multicomponents analysis are close to each other and permit us to precise the value of Z. We test this procedure on several events (in various regions of the magnetosphere) in order to get more precise wave number measurements from the single spacecraft analysis. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7-SPACE-2010-1) under grant agreement n. 284520 (MAARBLE).

Plasma Waves Associated with Mass-Loaded Comets

NASA Technical Reports Server (NTRS)

Tsurutani, Bruce; Glassmeier, Karl-Heinz

2015-01-01

Plasma waves and instabilities are integrally involved with the plasma "pickup" process and the mass loading of the solar wind (thus the formation of ion tails and the magnetic tails). Anisotropic plasmas generated by solar wind-comet interactions (the bow shock, magnetic field pileup) cause the generation of plasma waves which in turn "smooth out" these discontinuities. The plasma waves evolve and form plasma turbulence. Comets are perhaps the best "laboratories" to study waves and turbulence because over time (and distance) one can identify the waves and their evolution. We will argue that comets in some ways are better laboratories than magnetospheres, interplanetary space and fusion devices to study nonlinear waves and their evolution.

The dissipation of electromagnetic waves in plasmas

NASA Astrophysics Data System (ADS)

Basov, N. G.

The present anthology includes articles concerning the experimental study of the interaction of high power electromagnetic waves with collisionless plasmas and with electrons. Among the topics covered are the nonlinear dissipation of electromagnetic waves in inhomogeneous collisionless plasmas, the collisionless absorption of electromagnetic waves in plasmas and 'slow' nonlinear phenomena, the nonlinear effects of electron plasma waves propagating in an inhomogeneous plasma layer, and secondary-emission microwave discharges having large electron transit angles.

Dust ion-acoustic shock waves in magnetized pair-ion plasma with kappa distributed electrons

NASA Astrophysics Data System (ADS)

Kaur, B.; Singh, M.; Saini, N. S.

2018-01-01

We have performed a theoretical and numerical analysis of the three dimensional dynamics of nonlinear dust ion-acoustic shock waves (DIASWs) in a magnetized plasma, consisting of positive and negative ion fluids, kappa distributed electrons, immobile dust particulates along with positive and negative ion kinematic viscosity. By employing the reductive perturbation technique, we have derived the nonlinear Zakharov-Kuznetsov-Burgers (ZKB) equation, in which the nonlinear forces are balanced by dissipative forces (associated with kinematic viscosity). It is observed that the characteristics of DIASWs are significantly affected by superthermality of electrons, magnetic field strength, direction cosines, dust concentration, positive to negative ions mass ratio and viscosity of positive and negative ions.

Toward remote sensing with broadband terahertz waves

NASA Astrophysics Data System (ADS)

Clough, Benjamin W.

Terahertz electromagnetic waves, defined as the frequency region between 0.1 and 10 terahertz on the electromagnetic spectrum, have demonstrated remarkable usefulness for imaging and chemical identification with the ability to penetrate many optically opaque barriers. Photon energies at these frequencies are relatively small (meV), which means the radiation is non-ionizing and therefore considered biologically innocuous. With the growing list of applications and demand for terahertz technology, there is a need to develop innovative terahertz sources and detectors that can overcome existing limitations in power, bandwidth, and operating range. Although terahertz radiation has demonstrated unique and exceptional abilities, it has also presented several fundamental challenges. Most notably, the water vapor absorption of terahertz waves in air at habitable altitudes is greater than 100 dB/km. There is an immediate push to utilize the material and vapor identification abilities of terahertz radiation, while extending the effective distances over which the technology can be used. Remote terahertz detection, until recently, was thought to be impossible due to the high water content in the atmosphere, limited signal collection geometries, and solid state materials necessary for generation and detection. This dissertation focuses on laser air-photonics used for sensing short pulses of electromagnetic radiation. Through the ionization process, the very air that we breathe is capable of generating terahertz field strengths greater than 1 MV/cm, useful bandwidths over 100 terahertz, and highly directional emission patterns. Following ionization and plasma formation, the emitted plasma acoustics or fluorescence can be modulated by an external field to serve as omnidirectional, broadband, electromagnetic sensor. A deeper understanding of terahertz wave-plasma interaction is used to develop methods for retrieving coherent terahertz wave information that can be encoded into plasma acoustic and fluorescence wave emission; the ultimate goal aimed at overcoming fundamental limitations of the current terahertz technology. A synthesized bichromatic field-induced laser plasma is used to study effects of electron velocity redistribution inside the plasma filament, and a technique for obtaining a direct correlation between the terahertz field and the plasma acoustic or fluorescence emission is engineered. This dissertation presents significant advances in terahertz air photonics that help to close the "THz gap" once existing between electronic and optical frequencies, and the acoustic and fluorescence detection methodologies developed provide promising new avenues for extending the useful range of terahertz wave technology.

Preface to Special Topic: Advances in Radio Frequency Physics in Fusion Plasmas

NASA Astrophysics Data System (ADS)

Tuccillo, Angelo A.; Phillips, Cynthia K.; Ceccuzzi, Silvio

2014-06-01

It has long been recognized that auxiliary plasma heating will be required to achieve the high temperature, high density conditions within a magnetically confined plasma in which a fusion "burn" may be sustained by copious fusion reactions. Consequently, the application of radio and microwave frequency electromagnetic waves to magnetically confined plasma, commonly referred to as RF, has been a major part of the program almost since its inception in the 1950s. These RF waves provide heating, current drive, plasma profile control, and Magnetohydrodynamics (MHD) stabilization. Fusion experiments employ electromagnetic radiation in a wide range of frequencies, from tens of MHz to hundreds of GHz. The fusion devices containing the plasma are typically tori, axisymmetric or non, in which the equilibrium magnetic fields are composed of a strong toroidal magnetic field generated by external coils, and a poloidal field created, at least in the symmetric configurations, by currents flowing in the plasma. The waves are excited in the peripheral regions of the plasma, by specially designed launching structures, and subsequently propagate into the core regions, where resonant wave-plasma interactions produce localized heating or other modification of the local equilibrium profiles. Experimental studies coupled with the development of theoretical models and advanced simulation codes over the past 40+ years have led to an unprecedented understanding of the physics of RF heating and current drive in the core of magnetic fusion devices. Nevertheless, there are serious gaps in our knowledge base that continue to have a negative impact on the success of ongoing experiments and that must be resolved as the program progresses to the next generation devices and ultimately to "demo" and "fusion power plant." A serious gap, at least in the ion cyclotron (IC) range of frequencies and partially in the lower hybrid frequency ranges, is the difficulty in coupling large amount of power to the plasma while minimizing the interaction between the plasma and launching structures. These potentially harmful interactions between the plasma and the vessel and launching structures are challenging: (i) significant and variable loss of power in the edge regions of confined plasmas and surrounding vessel structures adversely affect the core plasma performance and lifetime of a device; (ii) the launcher design is partly "trial and error," with the consequence that launchers may have to be reconfigured after initial tests in a given device, at an additional cost. Over the broader frequency range, another serious gap is a quantitative lack of understanding of the combined effects of nonlinear wave-plasma processes, energetic particle interactions and non-axisymmetric equilibrium effects on determining the overall efficiency of plasma equilibrium and stability profile control techniques using RF waves. This is complicated by a corresponding lack of predictive understanding of the time evolution of transport and stability processes in fusion plasmas.

Plasma Waves in the Magnetosheath of Venus

NASA Technical Reports Server (NTRS)

Strangeway, Robert J.

1996-01-01

Research supported by this grant is divided into three basic topics of investigation. These are: (1) Plasma waves in the Venus magnetosheath, (2) Plasma waves in the Venus foreshock and solar wind, (3) plasma waves in the Venus nightside ionosphere and ionotail. The main issues addressed in the first area - Plasma waves in the Venus magnetosheath - dealt with the wave modes observed in the magnetosheath and upper ionosphere, and whether these waves are a significant source of heating for the topside ionosphere. The source of the waves was also investigated. In the second area - Plasma waves in the Venus foreshock and solar wind, we carried out some research on waves observed upstream of the planetary bow shock known as the foreshock. The foreshock and bow shock modify the ambient magnetic field and plasma, and need to be understood if we are to understand the magnetosheath. Although most of the research was directed to wave observations on the dayside of the planet, in the last of the three basic areas studied, we also analyzed data from the nightside. The plasma waves observed by the Pioneer Venus Orbiter on the nightside continue to be of considerable interest since they have been cited as evidence for lightning on Venus.

Second harmonic generation of q-Gaussian laser beam in preformed collisional plasma channel with nonlinear absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Naveen, E-mail: naveens222@rediffmail.com; Singh, Arvinder, E-mail: arvinder6@lycos.com; Singh, Navpreet, E-mail: navpreet.nit@gmail.com

2015-11-15

This paper presents a scheme for second harmonic generation of an intense q-Gaussian laser beam in a preformed parabolic plasma channel, where collisional nonlinearity is operative with nonlinear absorption. Due to nonuniform irradiance of intensity along the wavefront of the laser beam, nonuniform Ohmic heating of plasma electrons takes place. Due to this nonuniform heating of plasma, the laser beam gets self-focused and produces strong density gradients in the transverse direction. The generated density gradients excite an electron plasma wave at pump frequency that interacts with the pump beam to produce its second harmonics. The formulation is based on amore » numerical solution of the nonlinear Schrodinger wave equation in WKB approximation followed by moment theory approach. A second order nonlinear differential equation governing the propagation dynamics of the laser beam with distance of propagation has been obtained and is solved numerically by Runge Kutta fourth order technique. The effect of nonlinear absorption on self-focusing of the laser beam and conversion efficiency of its second harmonics has been investigated.« less

Cylindrical and spherical solitary waves in an electron-acoustic plasma with vortex electron distribution

NASA Astrophysics Data System (ADS)

Demiray, Hilmi; El-Zahar, Essam R.

2018-04-01

We consider the nonlinear propagation of electron-acoustic waves in a plasma composed of a cold electron fluid, hot electrons obeying a trapped/vortex-like distribution, and stationary ions. The basic nonlinear equations of the above described plasma are re-examined in the cylindrical (spherical) coordinates by employing the reductive perturbation technique. The modified cylindrical (spherical) KdV equation with fractional power nonlinearity is obtained as the evolution equation. Due to the nature of nonlinearity, this evolution equation cannot be reduced to the conventional KdV equation. A new family of closed form analytical approximate solution to the evolution equation and a comparison with numerical solution are presented and the results are depicted in some 2D and 3D figures. The results reveal that both solutions are in good agreement and the method can be used to obtain a new progressive wave solution for such evolution equations. Moreover, the resulting closed form analytical solution allows us to carry out a parametric study to investigate the effect of the physical parameters on the solution behavior of the modified cylindrical (spherical) KdV equation.

Charged dust phenomena in the near-Earth space environment.

PubMed

Scales, W A; Mahmoudian, A

2016-10-01

Dusty (or complex) plasmas in the Earth's middle and upper atmosphere ultimately result in exotic phenomena that are currently forefront research issues in the space science community. This paper presents some of the basic criteria and fundamental physical processes associated with the creation, evolution and dynamics of dusty plasmas in the near-Earth space environment. Recent remote sensing techniques to probe naturally created dusty plasma regions are also discussed. These include ground-based experiments employing high-power radio wave interaction. Some characteristics of the dusty plasmas that are actively produced by space-borne aerosol release experiments are discussed. Basic models that may be used to investigate the characteristics of such dusty plasma regions are presented.

Full-wave feasibility study of anti-radar diagnostic of magnetic field based on O-X mode conversion and oblique reflectometry imaging

DOE PAGES

Meneghini, Orso; Volpe, Francesco A.

2016-08-19

An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contain information on the magnetic field vector B at the cutoff layer. By probing the plasma with different wave frequencies it provides the radial profile of B. Full-wave finite-element simulations are presented here in 2D slab geometry.more » Modeling confirms the existence of a minimum in reflectivity that depends on the magnetic field at the cutoff, as expected from mode conversion physics, giving confidence in the feasibility of the diagnostic. We proposed an reflectometric approach in order to yield superior signal-to-noise ratio and to access wider ranges of density and magnetic field, compared with related radiometric techniques that require the plasma to emit Electron Bernstein Waves. Due to computational limitations, frequencies of 10-20 GHz were considered in this initial study. Furthermore, frequencies above the edge electron-cyclotron frequency (f >28 GHz here) would be preferable for the experiment, because the upper hybrid resonance and right cutoff would lie in the plasma, and would help separate the O-mode of interest from spurious X-waves.« less

Full-wave feasibility study of anti-radar diagnostic of magnetic field based on O-X mode conversion and oblique reflectometry imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meneghini, Orso; Volpe, Francesco A., E-mail: fvolpe@columbia.edu

An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contains information on the magnetic field vector B at the cutoff layer. Probing the plasma with different wave frequencies provides the radial profile of B. Full-wave finite-element simulations are presented here in 2D slab geometry. Modeling confirmsmore » the existence of a minimum in reflectivity that depends on the magnetic field at the cutoff, as expected from mode conversion physics, giving confidence in the feasibility of the diagnostic. The proposed reflectometric approach is expected to yield superior signal-to-noise ratio and to access wider ranges of density and magnetic field, compared with related radiometric techniques that require the plasma to emit electron Bernstein waves. Due to computational limitations, frequencies of 10-20 GHz were considered in this initial study. Frequencies above the edge electron-cyclotron frequency (f > 28 GHz here) would be preferable for the experiment, because the upper hybrid resonance and right cutoff would lie in the plasma, and would help separate the O-mode of interest from spurious X-waves.« less

Science, technology, and application of THz air photonics

NASA Astrophysics Data System (ADS)

Lu, X. F.; Clough, B.; Ho, I.-C.; Kaur, G.; Liu, J.; Karpowicz, N.; Dai, J. M.; Zhang, X.-C.

2010-11-01

The significant scientific and technological potential of terahertz (THz) wave sensing and imaging has been attracted considerable attention within many fields of research. However, the development of remote, broadband THz wave sensing technology is lagging behind the compelling needs that exist in the areas of astronomy, global environmental monitoring, and homeland security. This is due to the challenge posed by high absorption of ambient moisture in the THz range. Although various time-domain THz detection techniques have recently been demonstrated, the requirement for an on-site bias or forward collection of the optical signal inevitably prohibits their applications for remote sensing. The objective of this paper is to report updated THz air-plasma technology to meet this great challenge of remote sensing. A focused optical pulse (mJ pulse energy and femtosecond pulse duration) in gas creates a plasma, which can serve to generate intense, broadband, and directional THz waves in the far field.

Gravitational Radiation of a Vibrating Physical String as a Model for the Gravitational Emission of an Astrophysical Plasma

NASA Astrophysics Data System (ADS)

Lewis, Ray A.; Modanese, Giovanni

Vibrating media offer an important testing ground for reconciling conflicts between General Relativity, Quantum Mechanics and other branches of physics. For sources like a Weber bar, the standard covariant formalism for elastic bodies can be applied. The vibrating string, however, is a source of gravitational waves which requires novel computational techniques, based on the explicit construction of a conserved and renormalized energy-momentum tensor. Renormalization (in a classical sense) is necessary to take into account the effect of external constraints, which affect the emission considerably. Our computation also relaxes usual simplifying assumptions like far-field approximation, spherical or plane wave symmetry, TT gauge and absence of internal interference. In a further step towards unification, the method is then adapted to give the radiation field of a transversal Alfven wave in a rarefied astrophysical plasma, where the tension is produced by an external static magnetic field.

Simulation on change of generic satellite radar cross section via artificially created plasma sprays

NASA Astrophysics Data System (ADS)

Chung, Shen Shou Max; Chuang, Yu-Chou

2016-06-01

Recent advancements in antisatellite missile technologies have proven the effectiveness of such attacks, and the vulnerability of satellites in such exercises inspires a new paradigm in RF Stealth techniques suitable for satellites. In this paper we examine the possibility of using artificially created plasma sprays on the surface of the satellite’s main body to alter its radar cross section (RCS). First, we briefly review past research related to RF Stealth using plasma. Next, we discuss the physics between electromagnetic waves and plasma, and the RCS number game in RF Stealth design. A comparison of RCS in a generic satellite and a more complicated model is made to illustrate the effect of the RCS number game, and its meaning for a simulation model. We also run a comparison between finite-difference-time-domain (FDTD) and multilevel fast multipole method (MLFMM) codes, and find the RCS results are very close. We then compare the RCS of the generic satellite and the plasma-covered satellite. The incident radar wave is a differentiated Gaussian monopulse, with 3 dB bandwidth between 1.2 GHz and 4 GHz, and we simulate three kinds of plasma density, with a characteristic plasma frequency ω P  =  0.1, 1, and 10 GHz. The electron-neutral collision frequency ν en is set at 0.01 GHz. We found the RCS of plasma-covered satellite is not necessarily smaller than the originally satellite. When ω P is 0.1 GHz, the plasma spray behaves like a dielectric, and there is minor reduction in the RCS. When ω P is 1 GHz, the X-Y cut RCS increases. When ω P is 10 GHz, the plasma behaves more like a metal to the radar wave, and stronger RCS dependency to frequency appears. Therefore, to use plasma as an RCS adjustment tool requires careful fine-tuning of plasma density and shape, in order to achieve the so-called plasma stealth effect.

Observation of helicon wave with m = 0 antenna in a weakly magnetized inductively coupled plasma source

NASA Astrophysics Data System (ADS)

Ellingboe, Bert; Sirse, Nishant; Moloney, Rachel; McCarthy, John

2015-09-01

Bounded whistler wave, called ``helicon wave,'' is known to produce high-density plasmas and has been exploited as a high density plasma source for many applications, including electric propulsion for spacecraft. In a helicon plasma source, an antenna wrapped around the magnetized plasma column launches a low frequency wave, ωce/2 >ωhelicon >ωce/100, in the plasma which is responsible for maintaining high density plasma. Several antenna designs have been proposed in order to match efficiently the wave modes. In our experiment, helicon wave mode is observed using an m = 0 antenna. A floating B dot probe, compensated to the capacitively coupled E field, is employed to measure axial-wave-field-profiles (z, r, and θ components) in the plasma at multiple radial positions as a function of rf power and pressure. The Bθ component of the rf-field is observed to be unaffected as the wave propagates in the axial direction. Power coupling between the antenna and the plasma column is identified and agrees with the E, H, and wave coupling regimes previously seen in M =1 antenna systems. That is, the Bz component of the rf-field is observed at low plasma density as the Bz component from the antenna penetrates the plasma. The Bz component becomes very small at medium density due to shielding at the centre of the plasma column; however, with increasing density, a sudden ``jump'' occurs in the Bz component above which a standing wave under the antenna with a propagating wave away from the antenna are observed.

Low-Frequency Waves in Space Plasmas

NASA Astrophysics Data System (ADS)

Keiling, Andreas; Lee, Dong-Hun; Nakariakov, Valery

2016-02-01

Low-frequency waves in space plasmas have been studied for several decades, and our knowledge gain has been incremental with several paradigm-changing leaps forward. In our solar system, such waves occur in the ionospheres and magnetospheres of planets, and around our Moon. They occur in the solar wind, and more recently, they have been confirmed in the Sun's atmosphere as well. The goal of wave research is to understand their generation, their propagation, and their interaction with the surrounding plasma. Low-frequency Waves in Space Plasmas presents a concise and authoritative up-to-date look on where wave research stands: What have we learned in the last decade? What are unanswered questions? While in the past waves in different astrophysical plasmas have been largely treated in separate books, the unique feature of this monograph is that it covers waves in many plasma regions, including: Waves in geospace, including ionosphere and magnetosphere Waves in planetary magnetospheres Waves at the Moon Waves in the solar wind Waves in the solar atmosphere Because of the breadth of topics covered, this volume should appeal to a broad community of space scientists and students, and it should also be of interest to astronomers/astrophysicists who are studying space plasmas beyond our Solar System.

Ion acoustic shock waves in plasmas with warm ions and kappa distributed electrons and positrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hussain, S.; Mahmood, S.; Hafeez Ur-Rehman

2013-06-15

The monotonic and oscillatory ion acoustic shock waves are investigated in electron-positron-ion plasmas (e-p-i) with warm ions (adiabatically heated) and nonthermal kappa distributed electrons and positrons. The dissipation effects are included in the model due to kinematic viscosity of the ions. Using reductive perturbation technique, the Kadomtsev-Petviashvili-Burgers (KPB) equation is derived containing dispersion, dissipation, and diffraction effects (due to perturbation in the transverse direction) in e-p-i plasmas. The analytical solution of KPB equation is obtained by employing tangent hyperbolic (Tanh) method. The analytical condition for the propagation of oscillatory and monotonic shock structures are also discussed in detail. The numericalmore » results of two dimensional monotonic shock structures are obtained for graphical representation. The dependence of shock structures on positron equilibrium density, ion temperature, nonthermal spectral index kappa, and the kinematic viscosity of ions are also discussed.« less

Electron Bernstein Wave Research on NSTX and CDX-U

NASA Astrophysics Data System (ADS)

Taylor, G.; Efthimion, P. C.; Jones, B.; Bell, G. L.; Bers, A.; Bigelow, T. S.; Carter, M. D.; Harvey, R. W.; Ram, A. K.; Rasmussen, D. A.; Smirnov, A. P.; Wilgen, J. B.; Wilson, J. R.

2003-12-01

Studies of thermally emitted electron Bernstein waves (EBWs) on CDX-U and NSTX, via mode conversion (MC) to electromagnetic radiation, support the use of EBWs to measure the Te profile and provide local electron heating and current drive (CD) in overdense spherical torus plasmas. An X-mode antenna with radially adjustable limiters successfully controlled EBW MC on CDX-U and enhanced MC efficiency to ˜ 100%. So far the X-mode MC efficiency on NSTX has been increased by a similar technique to 40-50% and future experiments are focused on achieving ⩾ 80% MC. MC efficiencies on both machines agree well with theoretical predictions. Ray tracing and Fokker-Planck modeling for NSTX equilibria are being conducted to support the design of a 3 MW, 15 GHz EBW heating and CD system for NSTX to assist non-inductive plasma startup, current ramp up, and to provide local electron heating and CD in high β NSTX plasmas.

Electron acoustic solitons in magneto-rotating electron-positron-ion plasma with nonthermal electrons and positrons

NASA Astrophysics Data System (ADS)

Jilani, K.; Mirza, Arshad M.; Iqbal, J.

2015-02-01

The propagation of electron acoustic solitary waves (EASWs) in a magneto-rotating electron-positron-ion (epi) plasma containing cold dynamical electrons, nonthermal electrons and positrons obeying Cairns' distribution have been explored in the stationary background of massive positive ions. Through the linear dispersion relation (LDR) the effects of nonthermal components, magnetic field and rotation have been analyzed, wherein, various limiting cases have been deduced from the LDR. For nonlinear analysis, Korteweg-de Vries (KdV) equation is obtained using the reductive perturbation technique. It is found that in the presence of nonthermal positrons both hump and dip type solitons appear to excite, the structural properties of these solitary waves change drastically with magneto-rotating effects. The present work may be employed to explore and to understand the formation of electron acoustic solitary structures in the space and laboratory plasmas with nonthermal electrons and positrons under magneto-rotating effects.

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

NASA Astrophysics Data System (ADS)

Lempert, Walter R.; Adamovich, Igor V.

2014-10-01

The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed.

Continuous wave cavity ring down spectroscopy measurements of velocity distribution functions of argon ions in a helicon plasma.

PubMed

Chakraborty Thakur, Saikat; McCarren, Dustin; Carr, Jerry; Scime, Earl E

2012-02-01

We report continuous wave cavity ring down spectroscopy (CW-CRDS) measurements of ion velocity distribution functions (VDFs) in low pressure argon helicon plasma (magnetic field strength of 600 G, T(e) ≈ 4 eV and n ≈ 5 × 10(11) cm(-3)). Laser induced fluorescence (LIF) is routinely used to measure VDFs of argon ions, argon neutrals, helium neutrals, and xenon ions in helicon sources. Here, we describe a CW-CRDS diagnostic based on a narrow line width, tunable diode laser as an alternative technique to measure VDFs in similar regimes but where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopic technique; CW-CRDS can also provide a direct quantitative measurement of the absolute metastable state density. The proof of principle CW-CRDS measurements presented here are of the Doppler broadened absorption spectrum of Ar II at 668.6138 nm. Extrapolating from these initial measurements, it is expected that this diagnostic is suitable for neutrals and ions in plasmas ranging in density from 1 × 10(9) cm(-3) to 1 × 10(13) cm(-3) and target species temperatures less than 20 eV.

Continuous wave cavity ring down spectroscopy measurements of velocity distribution functions of argon ions in a helicon plasma

NASA Astrophysics Data System (ADS)

Chakraborty Thakur, Saikat; McCarren, Dustin; Carr, Jerry; Scime, Earl E.

2012-02-01

We report continuous wave cavity ring down spectroscopy (CW-CRDS) measurements of ion velocity distribution functions (VDFs) in low pressure argon helicon plasma (magnetic field strength of 600 G, Te ≈ 4 eV and n ≈ 5 × 1011 cm-3). Laser induced fluorescence (LIF) is routinely used to measure VDFs of argon ions, argon neutrals, helium neutrals, and xenon ions in helicon sources. Here, we describe a CW-CRDS diagnostic based on a narrow line width, tunable diode laser as an alternative technique to measure VDFs in similar regimes but where LIF is inapplicable. Being an ultra-sensitive, cavity enhanced absorption spectroscopic technique; CW-CRDS can also provide a direct quantitative measurement of the absolute metastable state density. The proof of principle CW-CRDS measurements presented here are of the Doppler broadened absorption spectrum of Ar II at 668.6138 nm. Extrapolating from these initial measurements, it is expected that this diagnostic is suitable for neutrals and ions in plasmas ranging in density from 1 × 109 cm-3 to 1 × 1013 cm-3 and target species temperatures less than 20 eV.

Nonlinear Coherent Structures, Microbursts and Turbulence

NASA Astrophysics Data System (ADS)

Lakhina, G. S.

2015-12-01

Nonlinear waves are found everywhere, in fluids, atmosphere, laboratory, space and astrophysical plasmas. The interplay of nonlinear effects, dispersion and dissipation in the medium can lead to a variety of nonlinear waves and turbulence. Two cases of coherent nonlinear waves: chorus and electrostatic solitary waves (ESWs) and their impact on modifying the plasma medium are discussed. Chorus is a right-hand, circularly-polarized electromagnetic plane wave. Dayside chorus is a bursty emission composed of rising frequency "elements" with duration of ~0.1 to 1.0 s. Each element is composed of coherent subelements with durations of ~1 to 100 ms or more. The cyclotron resonant interaction between energetic electrons and the coherent chorus waves is studied. An expression for the pitch angle transport due to this interaction is derived considering a Gaussian distribution for the time duration of the chorus elements. The rapid pitch scattering can provide an explanation for the ionospheric microbursts of ~0.1 to 0.5 s in bremsstrahlung x-rays formed by ~10-100 keV precipitating electrons. On the other hand, the ESWs are observed in the electric field component parallel to the background magnetic field, and are usually bipolar or tripolar. Generation of coherent ESWs has been explained in terms of nonlinear fluid models of ion- and electron-acoustic solitons and double layers (DLs) based on Sagdeev pseudopotential technique. Fast Fourier transform of electron- and ion-acoustic solitons/DLs produces broadband wave spectra which can explain the properties of the electrostatic turbulence observed in the magnetosheath and plasma sheet boundary layer, and in the solar wind, respectively.

Properties, propagation, and excitation of EMIC waves observed by MMS: A case study

NASA Astrophysics Data System (ADS)

Zhang, J.; Boardsen, S. A.; Coffey, V. N.; Chandler, M. O.; Saikin, A.; Mello, E. M.; Russell, C. T.; Torbert, R. B.; Fuselier, S. A.; Giles, B. L.; Gershman, D. J.

2017-12-01

Electromagnetic ion cyclotron (EMIC) waves (0.1-5 Hz) play an important role in particle dynamics in the Earth's magnetosphere. EMIC waves are preferentially excited in regions where hot anisotropic ions and cold dense plasma populations spatially overlap. While the generation region of EMIC waves is usually on or near the magnetic equatorial plane in the inner magnetosphere, EMIC waves have both equatorial and off-equator source regions on the dayside in the compressed outer magnetosphere. Using field and plasma measurements from the Magnetospheric Multiscale (MMS) mission, we perform a case study of EMIC waves and associated local plasma conditions observed on 19 October 2015. From 0315 to 0810 UT, before crossing the magnetopause into the magnetosheath, all four MMS spacecraft detected long-lasting He+-band EMIC wave emissions around local noon (MLT = 12.7 - 14.0) at high L-shells (L = 8.8 - 15.2) and low magnetic latitudes (MLAT = -21.8º - -30.3º). Energetic (> 1 keV) and anisotropic ions were present throughout this event that was in the recovery phase of a weak geomagnetic storm (min. Dst = -48 nT at 1000 UT on 18 October 2015). The testing of linear theory suggests that the EMIC waves were excited locally. Although the wave event is dominated by small normal angles, its polarization is mixed with right- and left-handedness and its propagation is bi-directional with regard to the background magnetic field. The short inter-spacecraft distances (as low as 15 km) of the MMS mission make it possible to accurately determine the k vector of the waves using the phase difference technique. Preliminary analysis finds that the k vector magnitude, phase speed, and wavelength of the 0.3-Hz wave packet at 0453:55 UT are 0.005 km-1, 372.9 km/s, and 1242.9 km, respectively. We will discuss the characteristics of the wave and particle measurements and their significance in this locale.

Properties, Propagation, and Excitation of EMIC Waves Properties, Propagation, and Excitation of EMIC Waves

NASA Technical Reports Server (NTRS)

Zhang, Jichun; Coffey, Victoria N.; Chandler, Michael O.; Boardsen, Scott A.; Saikin, Anthony A.; Mello, Emily M.; Russell, Christopher T.; Torbert, Roy B.; Fuselier, Stephen A.; Giles, Barbara L.;

Relationship between directions of wave and energy propagation for cold plasma waves

NASA Technical Reports Server (NTRS)

Musielak, Zdzislaw E.

1986-01-01

The dispersion relation for plasma waves is considered in the 'cold' plasma approximation. General formulas for the dependence of the phase and group velocities on the direction of wave propagation with respect to the local magnetic field are obtained for a cold magnetized plasma. The principal cold plasma resonances and cut-off frequencies are defined for an arbitrary angle and are used to establish basic regimes of frequency where the cold plasma waves can propagate or can be evanescent. The relationship between direction of wave and energy propagation, for cold plasma waves in hydrogen atmosphere, is presented in the form of angle diagrams (angle between group velocity and magnetic field versus angle between phase velocity and magnetic field) and polar diagrams (also referred to as 'Friedrich's diagrams') for different directions of wave propagation. Morphological features of the diagrams as well as some critical angles of propagation are discussed.

The Radio Plasma Imager Investigation on the IMAGE Spacecraft

NASA Technical Reports Server (NTRS)

Reinisch, Bodo W.; Haines, D. M.; Bibl, K.; Cheney, G.; Galkin, I. A.; Huang, X.; Myers, S. H.; Sales, G. S.; Benson, R. F.; Fung, S. F.

1999-01-01

Radio plasma imaging uses total reflection of electromagnetic waves from plasmas whose plasma frequencies equal the radio sounding frequency and whose electron density gradients are parallel to the wave normals. The Radio Plasma Imager (RPI) has two orthogonal 500-m long dipole antennas in the spin plane for near omni-directional transmission. The third antenna is a 20-m dipole. Echoes from the magnetopause, plasmasphere and cusp will be received with three orthogonal antennas, allowing the determination of their angle-of-arrival. Thus it will be possible to create image fragments of the reflecting density structures. The instrument can execute a large variety of programmable measuring programs operating at frequencies between 3 kHz and 3 MHz. Tuning of the transmit antennas provides optimum power transfer from the 10 W transmitter to the antennas. The instrument can operate in three active sounding modes: (1) remote sounding to probe magnetospheric boundaries, (2) local (relaxation) sounding to probe the local plasma, and (3) whistler stimulation sounding. In addition, there is a passive mode to record natural emissions, and to determine the local electron density and temperature by using a thermal noise spectroscopy technique.

High-Performance Computational Modeling of ICRF Physics and Plasma-Surface Interactions in Alcator C-Mod

NASA Astrophysics Data System (ADS)

Jenkins, Thomas; Smithe, David

2016-10-01

Inefficiencies and detrimental physical effects may arise in conjunction with ICRF heating of tokamak plasmas. Large wall potential drops, associated with sheath formation near plasma-facing antenna hardware, give rise to high-Z impurity sputtering from plasma-facing components and subsequent radiative cooling. Linear and nonlinear wave excitations in the plasma edge/SOL also dissipate injected RF power and reduce overall antenna efficiency. Recent advances in finite-difference time-domain (FDTD) modeling techniques allow the physics of localized sheath potentials, and associated sputtering events, to be modeled concurrently with the physics of antenna near- and far-field behavior and RF power flow. The new methods enable time-domain modeling of plasma-surface interactions and ICRF physics in realistic experimental configurations at unprecedented spatial resolution. We present results/animations from high-performance (10k-100k core) FDTD/PIC simulations spanning half of Alcator C-Mod at mm-scale resolution, exploring impurity production due to localized sputtering (in response to self-consistent sheath potentials at antenna surfaces) and the physics of parasitic slow wave excitation near the antenna hardware and SOL. Supported by US DoE (Award DE-SC0009501) and the ALCC program.

Experiments on the Expansion of a Dense Plasma into a Background Magnetoplasma

NASA Astrophysics Data System (ADS)

Gekelman, Walter; Vanzeeland, Mike; Vincena, Steve; Pribyl, Pat

2003-10-01

There are many situations, which occur in space (coronal mass ejections, or are man-made (upper atmospheric detonations) as well as the initial stages of a supernovae, in which a dense plasma expands into a background magnetized plasma, that can support Alfvèn waves. The upgraded LArge Plasma Device (LAPD) is a machine, at UCLA, in which Alfvèn wave propagation in homogeneous and inhomogeneous plasmas has been studied. We describe a series of experiments,which involve the expansion of a dense (initially, n_laser-plasma/n_0≫1) laser-produced plasma into an ambient highly magnetized background plasma capable of supporting Alfvèn waves will be presented. The 150 MW laser is pulsed at the same 1 Hz repetition rate as the plasma in a highly reproducible experiment. The interaction results in the production of intense shear Alfvèn waves, as well as large density perturbations. The waves propagate away from the target and are observed to become plasma column resonances. In the initial phase the background magnetic field is expelled from a plasma bubble. Currents in the main body of the plasma are generated to neutralize the positively charged bubble. The current system which results, becomes that of a spectrum of shear Alfvèn waves. Spatial patterns of the wave magnetic fields waves are measured at over 10^4 locations. As the dense plasma expands across the magnetic field it seeds the column with shear waves. Most of the Alfvèn wave energy is in shear waves, which become field line resonances after a machine transit time. The interplay between waves, currents, inductive electric fields and space charge is analyzed in great detail. Dramatic movies of the measured wave fields and their associated currents will be presented. Work supported by ONR, and DOE /NSF.

In situ Observations of Magnetosonic Waves Modulated by Background Plasma Density

NASA Astrophysics Data System (ADS)

Yu, X.; Yuan, Z.; Huang, S.; Wang, D.; Funsten, H. O.

2017-12-01

We report in situ observations by the Van Allen Probe mission that magnetosonic (MS) waves are clearly relevant to appear relevant to the background plasma number density. As the satellite moved across dense and tenuous plasma alternatively, MS waves occurred only in lower density region. As the observed protons with 'ring' distributions provide free energy, local linear growth rates are calculated and show that magnetosonic waves can be locally excited in tenuous plasma. With variations of the background plasma density, the temporal variations of local wave growth rates calculated with the observed proton ring distributions, show a remarkable agreement with those of the observed wave amplitude. Therefore, the paper provides a direct proof that background plasma densities can modulate the amplitudes of magnetosonic waves through controlling the wave growth rates.

Propagation of electromagnetic waves in a weak collisional and fully ionized dusty plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Jieshu; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn; Gao, Ruilin

2016-04-15

The propagation properties of electromagnetic (EM) waves in fully ionized dusty plasmas is the subject of this study. The dielectric relationships for EM waves propagating in a fully ionized dusty plasma was derived from the Boltzmann distribution law, taking into consideration the collision and charging effects of the dust grains. The propagation properties of the EM waves in a dusty plasma were numerically calculated and studied. The study results indicated that the dusty grains with an increased radius and charge were more likely to impede the penetration of EM waves. Dust grains with large radii and high charge cause themore » attenuation of the EM wave in the dusty plasma. The different density of the dust in the plasma appeared to have no obvious effect on the transmission of the EM waves. The propagation of the EM waves in a weakly ionized dusty plasma varies from that in a fully ionized dusty plasma. The results are helpful to analyze the effects of dust in dusty plasmas and also provide a theoretical basis for future studies.« less

Lightning and plasma wave observations from the galileo flyby of venus.

PubMed

Gurnett, D A; Kurth, W S; Roux, A; Gendrin, R; Kennel, C F; Bolton, S J

1991-09-27

During the Galileo flyby of Venus the plasma wave instrument was used to search for impulsive radio signals from lightning and to investigate locally generated plasma waves. A total of nine events were detected in the frequency range from 100 kilohertz to 5.6 megahertz. Although the signals are weak, lightning is the only known source of these signals. Near the bow shock two types of locally generated plasma waves were observed, low-frequency electromagnetic waves from about 5 to 50 hertz and electron plasma oscillation at about 45 kilohertz. The plasma oscillations have considerable fine structure, possibly because of the formation of soliton-like wave packets.

Lightning and plasma wave observations from the Galileo flyby of Venus

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Kurth, W. S.; Roux, A.; Gendrin, R.; Kennel, C. F.; Bolton, S. J.

1991-01-01

Durig the Galileo flyby of Venus the plasma wave instrument was used to search for impulsive radio signals from lightning and to investigate locally generated plasma waves. A total of nine events were detected in the frequency range from 100 kilohertz to 5.6 megahertz. Although the signals are weak, lightning is the only known source of these signals. Near the bow shock two types of locally generated plasma waves were observed, low-frequency electromagnetic waves from about 5 to 50 hertz and electron plasma oscillation at about 45 kilohertz. The plasma oscillations have considerable fine structure, possibly because of the formation of soliton-like wave packets.

Quasi-thermal noise spectroscopy: The art and the practice

NASA Astrophysics Data System (ADS)

Meyer-Vernet, N.; Issautier, K.; Moncuquet, M.

2017-08-01

Quasi-thermal noise spectroscopy is an efficient tool for measuring in situ macroscopic plasma properties in space, using a passive wave receiver at the ports of an electric antenna. This technique was pioneered on spinning spacecraft carrying very long dipole antennas in the interplanetary medium—like ISEE-3 and Ulysses—whose geometry approached a "theoretician's dream." The technique has been extended to other instruments in various types of plasmas on board different spacecraft and will be implemented on several missions in the near future. Such extensions require different theoretical modelizations, involving magnetized, drifting, or dusty plasmas with various particle velocity distributions and antennas being shorter, biased, or made of unequal wires. We give new analytical approximations of the plasma quasi-thermal noise (QTN) and study how the constraints of the real world in space can (or cannot) be compatible with plasma detection by QTN spectroscopy. We consider applications to the missions Wind, Cassini, BepiColombo, Solar Orbiter, and Parker Solar Probe.

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.

Quantum effects on compressional Alfven waves in compensated semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amin, M. R.

2015-03-15

Amplitude modulation of a compressional Alfven wave in compensated electron-hole semiconductor plasmas is considered in the quantum magnetohydrodynamic regime in this paper. The important ingredients of this study are the inclusion of the particle degeneracy pressure, exchange-correlation potential, and the quantum diffraction effects via the Bohm potential in the momentum balance equations of the charge carriers. A modified nonlinear Schrödinger equation is derived for the evolution of the slowly varying amplitude of the compressional Alfven wave by employing the standard reductive perturbation technique. Typical values of the parameters for GaAs, GaSb, and GaN semiconductors are considered in analyzing the linearmore » and nonlinear dispersions of the compressional Alfven wave. Detailed analysis of the modulation instability in the long-wavelength regime is presented. For typical parameter ranges of the semiconductor plasmas and at the long-wavelength regime, it is found that the wave is modulationally unstable above a certain critical wavenumber. Effects of the exchange-correlation potential and the Bohm potential in the wave dynamics are also studied. It is found that the effect of the Bohm potential may be neglected in comparison with the effect of the exchange-correlation potential in the linear and nonlinear dispersions of the compressional Alfven wave.« less

WAKES: Wavelet Adaptive Kinetic Evolution Solvers

NASA Astrophysics Data System (ADS)

Mardirian, Marine; Afeyan, Bedros; Larson, David

2016-10-01

We are developing a general capability to adaptively solve phase space evolution equations mixing particle and continuum techniques in an adaptive manner. The multi-scale approach is achieved using wavelet decompositions which allow phase space density estimation to occur with scale dependent increased accuracy and variable time stepping. Possible improvements on the SFK method of Larson are discussed, including the use of multiresolution analysis based Richardson-Lucy Iteration, adaptive step size control in explicit vs implicit approaches. Examples will be shown with KEEN waves and KEEPN (Kinetic Electrostatic Electron Positron Nonlinear) waves, which are the pair plasma generalization of the former, and have a much richer span of dynamical behavior. WAKES techniques are well suited for the study of driven and released nonlinear, non-stationary, self-organized structures in phase space which have no fluid, limit nor a linear limit, and yet remain undamped and coherent well past the drive period. The work reported here is based on the Vlasov-Poisson model of plasma dynamics. Work supported by a Grant from the AFOSR.

Plasma Pancakes and Deep Cavities Generated by High Power Radio Waves from the Arecibo Observatory

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Briczinski, S. J., Jr.; Zawdie, K.; Huba, J.; Siefring, C. L.; Sulzer, M. P.; Nossa, E.; Aponte, N.; Perillat, P.; Jackson-Booth, N.

2017-12-01

Breakdown of the neutral atmosphere at ionospheric altitudes can be achieved with high power HF waves that reflect on the bottomside of the ionosphere. For overdense heating (i.e., wave frequency < maximum plasma frequency in the F-layer), the largest electric fields in the plasma are found just below the reflection altitude. There, electromagnetic waves are converted into electron plasma (Langmir) waves and ion acoustic waves. These waves are measured by scattering of the 430 MHz radar at Arecibo to from an enhanced plasma line. The photo-electron excitation of Langmuir waves yields a weaker plasma-line profile that shows the complete electron profile with the radar. Once HF enhanced Langmuir waves are formed, they can accelerate the photo-electron population to sufficient energies for neutral breakdown and enhanced ionization inside the HF Radio Beam. Plasma pancakes are produced because the breakdown process continues to build up plasma on bottom of the breakdown clouds and recombination occurs on the older breakdown plasma at the top of these clouds. Thus, the plasma pancake falls with altitude from the initial HF wave reflection altitude near 250 km to about 160 km where ion-electron recombination prevents the plasma cloud from being sustained by the high power HF. Experiments in March 2017 have produced plasma pancakes with about 100 Mega-Watts effective radiated power 5.1 MHz with the Arecibo HF Facility. Observations using the 430 MHz radar show falling plasma pancakes that disappear at low altitudes and reform at the F-layer critical reflection altitude. Sometimes the periodic and regular falling motion of the plasma pancakes is influenced by Acoustic Gravity Waves (AGW) propagating through the modified HF region. A rising AGW can cause the plasma pancake to reside at nearly constant altitude for 10 to 20 minutes. Dense cavities are also produced by high power radio waves interacting with the F-Layer. These structures are observed with the Arecibo 430 MHz radar as intense bight-outs in the plasma profile. Multiple cavities are seen simultaneously.

Plasma wave observations at comet giacobini-zinner.

PubMed

Scarf, F L; Coroniti, F V; Kennel, C F; Gurnett, D A; Ip, W H; Smith, E J

1986-04-18

The plasma wave instrument on the International Cometary Explorer (ICE) detected bursts of strong ion acoustic waves almost continuously when the spacecraft was within 2 million kilometers of the nucleus of comet Giacobini-Zinner. Electromagnetic whistlers and low-level electron plasma oscillations were also observed in this vast region that appears to be associated with heavy ion pickup. As ICE came closer to the anticipated location of the bow shock, the electromagnetic and electrostatic wave levels increased significantly, but even in the midst of this turbulence the wave instrument detected structures with familiar bow shock characteristics that were well correlated with observations of localized electron heating phenomena. Just beyond the visible coma, broadband waves with amplitudes as high as any ever detected by the ICE plasma wave instrument were recorded. These waves may account for the significant electron heating observed in this region by the ICE plasma probe, and these observations of strong wave-particle interactions may provide answers to longstanding questions concerning ionization processes in the vicinity of the coma. Near closest approach, the plasma wave instrument detected broadband electrostatic noise and a changing pattern of weak electron plasma oscillations that yielded a density profile for the outer layers of the cold plasma tail. Near the tail axis the plasma wave instrument also detected a nonuniform flux of dust impacts, and a preliminary profile of the Giacobini-Zinner dust distribution for micrometer-sized particles is presented.

Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique

PubMed Central

Park, Choon-Sang; Kim, Dong Ha; Shin, Bhum Jae; Tae, Heung-Sik

2016-01-01

This work presents a study on the preparation of plasma-polymerized aniline (pPANI) nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ) device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES) techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), and gel permeation chromatography (GPC) techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight (Mw), about 533 kDa with 1.9 polydispersity index (PDI). This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique. PMID:28787838

Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique.

PubMed

Park, Choon-Sang; Kim, Dong Ha; Shin, Bhum Jae; Tae, Heung-Sik

2016-01-11

This work presents a study on the preparation of plasma-polymerized aniline (pPANI) nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ) device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES) techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), and gel permeation chromatography (GPC) techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight ( M w ), about 533 kDa with 1.9 polydispersity index (PDI). This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.

Co-Investigator Proposal for Enstrophy - - Filamentation of Auroral Currents

NASA Technical Reports Server (NTRS)

Kintner, Paul M.

2000-01-01

Cornell University provided three instruments for the Enstrophy experiment: an electric field meter, a plasma wave receiver, and a magnetometer for measuring FAC. The electric field meter consisted of a 6 m Weitzmann boom system with analog signal processing and 12 bit ADC, which yielded one electric field component instantaneously and a two dimensional electric field every half spin. The plasma wave receiver used the same sensing system with the addition of pre-amplifiers in the spheres to sense plasma waves up to and including the electron Langmuir frequency. Signal processing employed a variety of continuous and snap shot techniques depending on the frequency range and band width. The science magnetometer provided by Cornell University was a Billingsly design fluxgate previously used on spacecraft missions but without radiation hardening. The magnetometer was mounted on a one meter, stiff aluminum "flop-down" boom. The Enstrophy payload was launched on february 11, 1999. Because of a design flaw in the event timers, the magnetometer boom was deployed before the payload despun. As a result the magnetometer separated mechanically from the boom but maintained electrical connection. This was confirmed by the calculation of the scalar magnetic field from all three vector components of the magnetic field. However, the individual vector values had no scientific value. The electric field and plasma wave instrumentation worked as designed. The data from these instruments was provided to the University of New Hampshire and to the Principal Investigator, as proposed.

Modeling RF Fields in Hot Plasmas with Parallel Full Wave Code

NASA Astrophysics Data System (ADS)

Spencer, Andrew; Svidzinski, Vladimir; Zhao, Liangji; Galkin, Sergei; Kim, Jin-Soo

2016-10-01

FAR-TECH, Inc. is developing a suite of full wave RF plasma codes. It is based on a meshless formulation in configuration space with adapted cloud of computational points (CCP) capability and using the hot plasma conductivity kernel to model the nonlocal plasma dielectric response. The conductivity kernel is calculated by numerically integrating the linearized Vlasov equation along unperturbed particle trajectories. Work has been done on the following calculations: 1) the conductivity kernel in hot plasmas, 2) a monitor function based on analytic solutions of the cold-plasma dispersion relation, 3) an adaptive CCP based on the monitor function, 4) stencils to approximate the wave equations on the CCP, 5) the solution to the full wave equations in the cold-plasma model in tokamak geometry for ECRH and ICRH range of frequencies, and 6) the solution to the wave equations using the calculated hot plasma conductivity kernel. We will present results on using a meshless formulation on adaptive CCP to solve the wave equations and on implementing the non-local hot plasma dielectric response to the wave equations. The presentation will include numerical results of wave propagation and absorption in the cold and hot tokamak plasma RF models, using DIII-D geometry and plasma parameters. Work is supported by the U.S. DOE SBIR program.

Shape modeling with family of Pearson distributions: Langmuir waves

NASA Astrophysics Data System (ADS)

Vidojevic, Sonja

2014-10-01

Two major effects of Langmuir wave electric field influence on spectral line shapes are appearance of depressions shifted from unperturbed line and an additional dynamical line broadening. More realistic and accurate models of Langmuir waves are needed to study these effects with more confidence. In this article we present distribution shapes of a high-quality data set of Langmuir waves electric field observed by the WIND satellite. Using well developed numerical techniques, the distributions of the empirical measurements are modeled by family of Pearson distributions. The results suggest that the existing theoretical models of energy conversion between an electron beam and surrounding plasma is more complex. If the processes of the Langmuir wave generation are better understood, the influence of Langmuir waves on spectral line shapes could be modeled better.

Speckles in interstellar radio-wave scattering

NASA Technical Reports Server (NTRS)

Desai, K. M.; Gwinn, C. R.; Reynolds, J.; King, E. A.; Jauncey, D.; Nicholson, G.; Flanagan, C.; Preston, R. A.; Jones, D. L.

1991-01-01

Observations of speckles in the scattering disk of the Vela pulsar are presented and speckle techniques for studying and circumventing scattering of radio waves by the turbulent interstellar plasma are discussed. The speckle pattern contains, in a hologrammatic fashion, complete information on the structure of the radio source as well as the distribution of the scattering material. Speckle observations of interstellar scattering of radio waves are difficult because of their characteristically short timescales and narrow bandwidths. Here, first observations are presented, taken at 13 cm wavelength with elements of the SHEVE VLBI network, of speckles in interstellar scattering.

Terahertz generation by beating two Langmuir waves in a warm and collisional plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiao-Bo; Qiao, Xin; Cheng, Li-Hong

2015-09-15

Terahertz (THz) radiation generated by beating of two Langmuir waves in a warm and collisional plasma is discussed theoretically. The critical angle between the two Langmuir waves and the critical wave-length (wave vector) of Langmuir waves for generating THz radiation are obtained analytically. Furthermore, the maximum radiation energy is obtained. We find that the critical angle, the critical wave-length, and the generated radiation energy strongly depend on plasma temperature and wave-length of the Langmuir waves. That is, the THz radiation generated by beating of two Langmuir waves in a warm and collisional plasma can be controlled by adjusting the plasmamore » temperature and the Langmuir wave-length.« less

Magnetospheric radio and plasma wave research - 1987-1990

NASA Technical Reports Server (NTRS)

Kurth, W. S.

1991-01-01

This review covers research performed in the area of magnetospheric plasma waves and wave-particle interactions as well as magnetospheric radio emissions. The report focuses on the near-completion of the discovery phase of radio and plasma wave phenomena in the planetary magnetospheres with the successful completion of the Voyager 2 encounters of Neptune and Uranus. Consideration is given to the advances made in detailed studies and theoretical investigations of radio and plasma wave phenomena in the terrestrial magnetosphere or in magnetospheric plasmas in general.

Progress on the development of FullWave, a Hot and Cold Plasma Parallel Full Wave Code

NASA Astrophysics Data System (ADS)

Spencer, J. Andrew; Svidzinski, Vladimir; Zhao, Liangji; Kim, Jin-Soo

2017-10-01

FullWave is being developed at FAR-TECH, Inc. to simulate RF waves in hot inhomogeneous magnetized plasmas without making small orbit approximations. FullWave is based on a meshless formulation in configuration space on non-uniform clouds of computational points (CCP) adapted to better resolve plasma resonances, antenna structures and complex boundaries. The linear frequency domain wave equation is formulated using two approaches: for cold plasmas the local cold plasma dielectric tensor is used (resolving resonances by particle collisions), while for hot plasmas the conductivity kernel is calculated. The details of FullWave and some preliminary results will be presented, including: 1) a monitor function based on analytic solutions of the cold-plasma dispersion relation; 2) an adaptive CCP based on the monitor function; 3) construction of the finite differences for approximation of derivatives on adaptive CCP; 4) results of 2-D full wave simulations in the cold plasma model in tokamak geometry using the formulated approach for ECRH, ICRH and Lower Hybrid range of frequencies. Work is supported by the U.S. DOE SBIR program.

Millimeter-Wave Generation Via Plasma Three-Wave Mixing

DTIC Science & Technology

1988-06-01

are coupled to a third space -charge wave with dispersion 2w W k -k k . (16) A plasma-loaded-waveguide mode is excited at the intersection of this...DISPERSION "FAST" W PLASMA WAVE Wc PLASMA WAVE A-lA oppositely directed EPWs with different phase velocities (wp/k., and wO/k. 2) are coupled to a third ... space -charge wave with dispersion 2w I- k k .(16) e 2 A plaama-loaded-waveguide mode is excited at the intersection of this coupled space-charge wave

Quantum Cascade Laser Absorption Spectroscopy as a Plasma Diagnostic Tool: An Overview

PubMed Central

Welzel, Stefan; Hempel, Frank; Hübner, Marko; Lang, Norbert; Davies, Paul B.; Röpcke, Jürgen

2010-01-01

The recent availability of thermoelectrically cooled pulsed and continuous wave quantum and inter-band cascade lasers in the mid-infrared spectral region has led to significant improvements and new developments in chemical sensing techniques using in-situ laser absorption spectroscopy for plasma diagnostic purposes. The aim of this article is therefore two-fold: (i) to summarize the challenges which arise in the application of quantum cascade lasers in such environments, and, (ii) to provide an overview of recent spectroscopic results (encompassing cavity enhanced methods) obtained in different kinds of plasma used in both research and industry. PMID:22163581

Quantum cascade laser absorption spectroscopy as a plasma diagnostic tool: an overview.

PubMed

Welzel, Stefan; Hempel, Frank; Hübner, Marko; Lang, Norbert; Davies, Paul B; Röpcke, Jürgen

2010-01-01

The recent availability of thermoelectrically cooled pulsed and continuous wave quantum and inter-band cascade lasers in the mid-infrared spectral region has led to significant improvements and new developments in chemical sensing techniques using in-situ laser absorption spectroscopy for plasma diagnostic purposes. The aim of this article is therefore two-fold: (i) to summarize the challenges which arise in the application of quantum cascade lasers in such environments, and, (ii) to provide an overview of recent spectroscopic results (encompassing cavity enhanced methods) obtained in different kinds of plasma used in both research and industry.

Study of edge turbulence in dimensionally similar laboratory plasmas

NASA Astrophysics Data System (ADS)

Stroth, Ulrich

2003-10-01

In recent years, the numerical simulation of turbulence has made considerable progress. Predictions are made for large plasma volumes taking into account realistic magnetic geometries. Because of diagnostic limitations, in fusion plasmas the means of experimental testing of the models are rather limited. Toroidal low-temperature plasmas offer the possibility for detailed comparisons between experiment and simulation. Due to the reduced plasma parameters, the relevant quantities can be measured in the entire plasma. At the same time, the relevant non-dimensional parameters can be comparable to those in the edge of fusion plasmas. This presentation reports on results from the torsatron TJ-K [1,2] operated with a low-temperature plasma. The data are compared with simulations using the drift-Alfven-wave code DALF3 [3]. Langmuir probe arrays with 64 tips are used to measure the spatial structure of the turbulence. The same analyses techniques are applied to experimental and numerical data. The measured properties of spectra and probability density functions are reproduced by the code. Although the plasma in experiment and simulation does not exhibit critical pressure gradients, the radial transport fluctuations are strongly intermittent in both cases. Using Hydrogen, Helium and Argon as working gases, the scale parameter ρs could be varied by more than a factor of ten. As predicted by theory, the size of the turbulent eddies increases with ρ_s. The measured cross-phase between density and potential fluctuations are small, indicating the importance of the drift-wave dynamics for the turbulence in toroidal plasmas. The wave number spectra decay with an exponent of -3 as one would expect for the enstrophy cascade in 2D turbulence. [1] N. Krause et al., Rev. Sci. Instr. 73, 3474 (2002) [2] C. Lechte et al., New J. of Physics 4, 34 (2002) [3] B. Scott, Plasma Phys. Contr. Fusion 39, 1635 (1997)

Multi-fluid Approach to High-frequency Waves in Plasmas. III. Nonlinear Regime and Plasma Heating

NASA Astrophysics Data System (ADS)

Martínez-Gómez, David; Soler, Roberto; Terradas, Jaume

2018-03-01

The multi-fluid modeling of high-frequency waves in partially ionized plasmas has shown that the behavior of magnetohydrodynamic waves in the linear regime is heavily influenced by the collisional interaction between the different species that form the plasma. Here, we go beyond linear theory and study large-amplitude waves in partially ionized plasmas using a nonlinear multi-fluid code. It is known that in fully ionized plasmas, nonlinear Alfvén waves generate density and pressure perturbations. Those nonlinear effects are more pronounced for standing oscillations than for propagating waves. By means of numerical simulations and analytical approximations, we examine how the collisional interaction between ions and neutrals affects the nonlinear evolution. The friction due to collisions dissipates a fraction of the wave energy, which is transformed into heat and consequently raises the temperature of the plasma. As an application, we investigate frictional heating in a plasma with physical conditions akin to those in a quiescent solar prominence.

The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

NASA Astrophysics Data System (ADS)

Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

2018-01-01

Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence seismology.

Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

NASA Astrophysics Data System (ADS)

Anderson, M. W.; O'Neil, T. M.; Dubin, D. H. E.; Gould, R. W.

2011-10-01

In the cold-fluid dispersion relation ω =ωp/[1+(k⊥/kz)2]1/2 for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k⊥/kz. As a result, for any frequency ω <ωp, there are infinitely many degenerate waves, all having the same value of k⊥/kz. On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz /dr=±(ωp2/ω2-1)1/2. Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

Low-threshold parametric excitation of the upper hybrid wave in experiments on electron-cyclotron resonance heating by an ordinary wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sysoeva, E. V., E-mail: tinlit@yandex.ru; Gusakov, E. Z.; Simonchik, L. V.

2016-07-15

The possibility of the low-threshold decay of an ordinary wave into an upper hybrid wave localized in a plasma column (or in an axisymmetric plasma filament) and a low-frequency wave is analyzed. It is shown that the threshold for such a decay, accompanied by the excitation of an ion-acoustic wave, can easily be overcome for plasma parameters typical of model experiments on the Granit linear plasma facility.

Inverse mirror plasma experimental device (IMPED) - a magnetized linear plasma device for wave studies

NASA Astrophysics Data System (ADS)

Bose, Sayak; Chattopadhyay, P. K.; Ghosh, J.; Sengupta, S.; Saxena, Y. C.; Pal, R.

2015-04-01

In a quasineutral plasma, electrons undergo collective oscillations, known as plasma oscillations, when perturbed locally. The oscillations propagate due to finite temperature effects. However, the wave can lose the phase coherence between constituting oscillators in an inhomogeneous plasma (phase mixing) because of the dependence of plasma oscillation frequency on plasma density. The longitudinal electric field associated with the wave may be used to accelerate electrons to high energies by exciting large amplitude wave. However when the maximum amplitude of the wave is reached that plasma can sustain, the wave breaks. The phenomena of wave breaking and phase mixing have applications in plasma heating and particle acceleration. For detailed experimental investigation of these phenomena a new device, inverse mirror plasma experimental device (IMPED), has been designed and fabricated. The detailed considerations taken before designing the device, so that different aspects of these phenomena can be studied in a controlled manner, are described. Specifications of different components of the IMPED machine and their flexibility aspects in upgrading, if necessary, are discussed. Initial results meeting the prerequisite condition of the plasma for such study, such as a quiescent, collisionless and uniform plasma, are presented. The machine produces δnnoise/n <= 1%, Luniform ~ 120 cm at argon filling pressure of ~10-4 mbar and axial magnetic field of B = 1090 G.

System and method for generating steady state confining current for a toroidal plasma fusion reactor

DOEpatents

Fisch, Nathaniel J.

1981-01-01

A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave RF energy is injected into said plasma to establish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected RF energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected RF energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range .DELTA.. The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width .DELTA. in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated in the plasma.

System and method for generating steady state confining current for a toroidal plasma fusion reactor

DOEpatents

Bers, Abraham

1981-01-01

A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave RF energy is injected into said plasma to estalish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected RF energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected RF energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range .DELTA.. The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width .DELTA. in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated inthe plasma.

Advanced density profile reflectometry; the state-of-the-art and measurement prospects for ITER

NASA Astrophysics Data System (ADS)

Doyle, E. J.

2006-10-01

Dramatic progress in millimeter-wave technology has allowed the realization of a key goal for ITER diagnostics, the routine measurement of the plasma density profile from millimeter-wave radar (reflectometry) measurements. In reflectometry, the measured round-trip group delay of a probe beam reflected from a plasma cutoff is used to infer the density distribution in the plasma. Reflectometer systems implemented by UCLA on a number of devices employ frequency-modulated continuous-wave (FM-CW), ultrawide-bandwidth, high-resolution radar systems. One such system on DIII-D has routinely demonstrated measurements of the density profile over a range of electron density of 0-6.4x10^19,m-3, with ˜25 μs time and ˜4 mm radial resolution, meeting key ITER requirements. This progress in performance was made possible by multiple advances in the areas of millimeter-wave technology, novel measurement techniques, and improved understanding, including: (i) fast sweep, solid-state, wide bandwidth sources and power amplifiers, (ii) dual polarization measurements to expand the density range, (iii) adaptive radar-based data analysis with parallel processing on a Unix cluster, (iv) high memory depth data acquisition, and (v) advances in full wave code modeling. The benefits of advanced system performance will be illustrated using measurements from a wide range of phenomena, including ELM and fast-ion driven mode dynamics, L-H transition studies and plasma-wall interaction. The measurement capabilities demonstrated by these systems provide a design basis for the development of the main ITER profile reflectometer system. This talk will explore the extent to which these reflectometer system designs, results and experience can be translated to ITER, and will identify what new studies and experimental tests are essential.

Studies on Charge Variation and Waves in Dusty Plasmas

NASA Astrophysics Data System (ADS)

Kausik, Siddhartha Sankar

Plasma and dust grains are both ubiquitous ingredients of the universe. The interplay between them has opened up a new and fascinating research domain, that of dusty plasmas, which contain macroscopic particles of solid matter besides the usual plasma constituents. The research in dusty plasmas received a major boost in the early eighties with Voyager spacecraft observation on the formation of Saturn rings. Dusty plasmas are defined as partially or fully-ionized gases that contain micron-sized particles of electrically charged solid material, either dielectric or conducting. The physics of dusty plasmas has recently been studied intensively because of its importance for a number of applications in space and laboratory plasmas. This thesis presents the experimental studies on charge variation and waves in dusty plasmas. The experimental observations are carried out in two different experimental devices. Three different sets of experiments are carried out in two different experimental devices. Three different sets of experiments are carried out to study the dust charge variation in a filament discharge argon plasma. The dust grains used in these experiments are grains of silver. In another get of experiment, dust acoustic waves are studied in a de glow discharge argon plasma. Alumina dust grains are sprinkled in this experiment. The diagnostic tools used in these experiments are Langmuir probe and Faraday cup. The instruments used in these experiments are electrometer, He-Ne laser and charge coupled device (CCD) camera. Langmuir probe is used to measure plasma parameters, while Faraday cup and electrometer are used to measure very low current (~pA) carried by a collimated dust beam. He-Ne laser illuminates the dust grains and CCD camera is used to capture the images of dust acoustic waves. Silver dust grains are produced in the dust chamber by gas-evaporation technique. Due to differential pressure maintained between the dust and plasma chambers, the dust grains move upward in the form of a collimated beam. Argon plasma is produced in an experimental setup consisting of a dust chamber, a plasma chamber and a diagnostic chamber (also called deflection chamber) by striking a discharge between incandescent tungsten filaments and the magnetic cage, which is grounded. Plasma thus produced is confined by a full line cusped magnetic field confinement system consisting of a cylindrically shaped cage made up of stainless steel channels filled up with cube shaped having 1.2 kG field strength at its surface.

Nonlinear, relativistic Langmuir waves in astrophysical magnetospheres

NASA Technical Reports Server (NTRS)

Chian, Abraham C.-L.

1987-01-01

Large amplitude, electrostatic plasma waves are relevant to physical processes occurring in the astrophysical magnetospheres wherein charged particles are accelerated to relativistic energies by strong waves emitted by pulsars, quasars, or radio galaxies. The nonlinear, relativistic theory of traveling Langmuir waves in a cold plasma is reviewed. The cases of streaming electron plasma, electronic plasma, and two-streams are discussed.

Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas

NASA Technical Reports Server (NTRS)

Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.

1997-01-01

We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.

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.

Introduction to Plasma Physics

NASA Astrophysics Data System (ADS)

Gurnett, Donald A.; Bhattacharjee, Amitava

2017-03-01

Preface; 1. Introduction; 2. Characteristic parameters of a plasma; 3. Single particle motions; 4. Waves in a cold plasma; 5. Kinetic theory and the moment equations; 6. Magnetohydrodynamics; 7. MHD equilibria and stability; 8. Discontinuities and shock waves; 9. Electrostatic waves in a hot unmagnetized plasma; 10. Waves in a hot magnetized plasma; 11. Nonlinear effects; 12. Collisional processes; Appendix A. Symbols; Appendix B. Useful trigonometric identities; Appendix C. Vector differential operators; Appendix D. Vector calculus identities; Index.

Demonstration of the hollow channel plasma wakefield accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gessner, Spencer J.

2016-09-17

A plasma wakefield accelerator is a device that converts the energy of a relativistic particle beam into a large-amplitude wave in a plasma. The plasma wave, or wakefield, supports an enormous electricfield that is used to accelerate a trailing particle beam. The plasma wakefield accelerator can therefore be used as a transformer, transferring energy from a high-charge, low-energy particle beam into a high-energy, low-charge particle beam. This technique may lead to a new generation of ultra-compact, high-energy particle accelerators. The past decade has seen enormous progress in the field of plasma wakefield acceleration with experimental demonstrations of the acceleration ofmore » electron beams by several gigaelectron-volts. The acceleration of positron beams in plasma is more challenging, but also necessary for the creation of a high-energy electron-positron collider. Part of the challenge is that the plasma responds asymmetrically to electrons and positrons, leading to increased disruption of the positron beam. One solution to this problem, first proposed over twenty years ago, is to use a hollow channel plasma which symmetrizes the response of the plasma to beams of positive and negative charge, making it possible to accelerate positrons in plasma without disruption. In this thesis, we describe the theory relevant to our experiment and derive new results when needed. We discuss the development and implementation of special optical devices used to create long plasma channels. We demonstrate for the first time the generation of meter-scale plasma channels and the acceleration of positron beams therein.« less

Studies on the transmission of sub-THz waves in magnetized inhomogeneous plasma sheath

NASA Astrophysics Data System (ADS)

Yuan, Kai; Shen, Linfang; Yao, Ming; Deng, Xiaohua; Chen, Zhou; Hong, Lujun

2018-01-01

There have been many studies on the sub-terahertz (sub-THz) wave transmission in reentry plasma sheaths. However, only some of them have paid attention to the transmission of sub-THz waves in magnetized plasma sheaths. In this paper, the transmission of sub-THz waves in both unmagnetized and magnetized reentry plasma sheaths was investigated. The impacts of temporal evolution of the plasma sheath on the wave transmission were studied. The transmission of "atmospheric window" frequencies in a magnetized plasma sheath was discussed in detail. According to the study, the power transmission rates (Tp) for the left hand circular (LHC) and the right hand circular modes in the magnetized plasma sheath are obviously higher and lower than those in the unmagnetized plasma sheath, respectively. The Tp of LHC mode increases with both wave frequency and external magnetic field strength. Also, the Tp of LHC mode in both magnetized and unmagnetized plasma sheaths varies with time due to the temporal evolution of the plasma sheath. Moreover, the performance of sub-THz waves in magnetized plasma sheath hints at a new approach to the "blackout" problem. The new approach, which is in the capability of modern technology, is to utilize the communication system operating at 140 GHz with an onboard magnet installed near the antenna.

The Nonlinear Coupling of Alfven and Lower Hybrid Waves in Space Plasma

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Singh, N.; Krivorutsky, E.

2003-01-01

Space plasmas support a wide variety of waves, and wave-particle interactions as well as wave-wave interactions which are of crucial importance to magnetospheric and ionospheric plasma behavior. The excitation of lower hybrid waves (LHWs), in particular, is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves may generate LHWs in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We present several examples of observational data which illustrate that the proposed mechanism is a plausible candidate to explain certain classes of LHW generation events in the ionosphere and magnetosphere and demonstrate electron and ion energization involving these processes. Furthermore, we will present results from particle-in-cell simulations showing the generation of particle drifts in response to an Alfven wave, resulting in excitation of waves and ion heating in a multi- ion plasma.

Plasma Technology as a New Preservation Technique

NASA Astrophysics Data System (ADS)

Rincón, R.; Calzada, M. D.

The preliminary results of using the surface wave discharge at the atmospheric pressure on groups of lentils and sherry Fino wine samples are presented. In this research, the capability of active species and UV radiation from the plasma, has been assessed on preservation of food. Besides, the generation and emission of both excited molecules in a metastable state N2}(B3Π {g-> A3}Σ u{+) and the de-excitation of species NO(A2}Σ {+) producing UV radiation have been also studied.

Effect of dust size distribution on ion-acoustic solitons in dusty plasmas with different dust grains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Dong-Ning; Yang, Yang; Yan, Qiang

Theoretical studies are carried out for ion acoustic solitons in multicomponent nonuniform plasma considering the dust size distribution. The Korteweg−de Vries equation for ion acoustic solitons is given by using the reductive perturbation technique. Two special dust size distributions are considered. The dependences of the width and amplitude of solitons on dust size parameters are shown. It is found that the properties of a solitary wave depend on the shape of the size distribution function of dust grains.

Jeans instability of rotating magnetized dusty plasma

NASA Astrophysics Data System (ADS)

Sharma, S.; Sutar, D. L.; Kumar, V.; Pensia, R. K.

2018-05-01

It has been shown that rotation has to play a predominant important role in the formation of many astrophysical objects and the stability of molecular clouds. In this paper the theoretical investigation of the presence of rotation in the magnetized dusty plasma. The general dispersion relation is obtained normal mode analysis technique, and we found the Alfven mode is modified due to the presence of rotation and magnetic field. The graphical presentation shows that rotation and Alfven wave velocity have a stabilizing in the system.

Alfven Eigenmode Control in DIII-D

NASA Astrophysics Data System (ADS)

Hu, W.; Olofsson, E.; Welander, A.; van Zeeland, M.; Collins, C.; Heidbrink, W.

2017-10-01

Alfven eigenmodes (AE) driven by fast ions from neutral beam and ion cyclotron heating are common in present day tokamak plasmas and are expected to be destabilized by alpha particles in future burning plasma experiments. Because these waves have been shown to cause loss and redistribution of fast ions which can impact plasma performance and potentially device integrity, developing control techniques for AEs is of paramount importance. In the DIII-D plasma control system, spectral analysis of real-time ECE data is used as a monitor of AE amplitude, frequency, and location. These values are then used for feedback control of the neutral beam power to control Alfven waves and reduce fast ion loss. This work describes tests of AE control experiments in the current ramp up phase, during which multiple Alfven eigenmodes are typically unstable and fast ion confinement is degraded significantly. Comparisons of neutron emission and confined fast ion profiles with and without active AE control will be made. Work supported by the U.S. Dept. of Energy under Award Number DE-FC02-04ER54698.

Alfvén Waves Generated by Expanding Plasmas in the Laboratory and in Space

NASA Astrophysics Data System (ADS)

Gekelman, W.; Vanzeeland, M.; Vincena, S.; Pribyl, P.

2002-12-01

There are many situations, which occur in space (coronal mass ejections, supernovas), or are man-made (upper atmospheric detonations) in which a dense plasma expands into a background magnetized plasma, that can support Alfvén waves. The LArge Plasma Device (LAPD) is a machine, at UCLA, in which Alfvén waves propagation in homogeneous and inhomogeneous plasmas has been studied. These will be briefly reviewed. Then a new class of experiments which involve the expansion of a dense (initially, n/no>>1) laser-produced plasma into an ambient highly magnetized background plasma capable of supporting Alfvén waves will be presented. The 150 MW laser is pulsed at the same 1 Hz repetition rate as the plasma in a highly reproducible experiment. The laser beam impacts a solid target such that the initial plasma burst is directed either along or across the magnetic field. The interaction results in the production of intense shear and compressional Alfvén waves, as well as large density perturbations. The waves propagate away from the target and are observed to become plasma column resonances. The magnetic fields of the waves are obtained with a 3-axis inductive probe. Spatial patterns of the magnetic fields associated with the waves and density perturbations are measured at over {10}4 locations and will be shown in dramatic movies. These are used to estimate the coupling efficiency of the laser energy and kinetic energy of the dense plasma into wave energy. The wave generation mechanism is due to field aligned return currents, which replace fast electrons escaping the initial blast. Work supported by ONR, DOE, and NSF

Overview of Current Drive Experiment-Upgrade (CDX-U)

NASA Astrophysics Data System (ADS)

Hwang, Y. S.; Choe, W.; Stutman, D.; Lo, E.; Menard, J.; Ono, M.; Jones, T. G.; Armstrong, R.

1996-11-01

The CDX-U tokamak is a spherical tokamak (ST) facility with R ≈ 32 cm, R/a >= 1.4, and B_TF ≈ 1 kG. With an OH power supply of 60 mV-S capability, experiments were conducted with Ip up to ~ 100 kA and q(a) >= 3.5. The ST plasma performance has been studied along with various MHD-related activities. By appropriate discharge programing, it was possible to obtain MHD-quiescent discharges with a factor of 2 - 3 improvement in the electron energy confinement. Recently, the outer vacuum vessel was replaced with a toroidally continuous stainless steel chamber to accomodate the fast wave antenna. With the newly installed antenna, preliminary heating experiments using high harmonic fast waves have been pursued. The success of fast wave heating is a crucial element for achieving high beta plasmas in ST devices such as NSTX. Also, preliminary electron ripple injection (ERI) experiments were performed in CDX-U to examine the feasibility of this technique for improving ST tokamak confinement. To support the ST physics investigation, various novel plasma profile diagnostics such as the multi-pass Thomson scattering, soft x-ray tomography, and tangential-phase-contrast-imaging systems are under development on CDX-U.

A note on supersonic flow control with nanosecond plasma actuator

NASA Astrophysics Data System (ADS)

Zheng, J. G.; Cui, Y. D.; Li, J.; Khoo, B. C.

2018-04-01

A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

Studies on absorption of EC waves in assisted startup experiment on FTU

NASA Astrophysics Data System (ADS)

Granucci, G.; Ricci, D.; Farina, D.; Figini, L.; Iraji, D.; Tudisco, O.; Ramponi, G.; Bin, W.

2012-09-01

Assistance of EC wave for plasma breakdown and current ramp up is the proposed scenario for the ITER case, characterized by low toroidal electric field. The experimental results on many tokamaks clearly indicate the capabilities of the proposed scheme to have a robust breakdown in ITER. The key aspect of this technique is the EC power required, strongly related to the absorption of the wave in the initial stage of plasma formation. This aspect is generally neglected due to the diagnostics difficulties in the plasma formation phase. As a consequence a multi-pass absorption scheme is usually considered reasonable, leading to a strong absorption after many reflections on the walls. The present study exploits the high temporal and spatial resolution of the fast scanning interferometer of FTU together with the measure of residual power obtained by a sniffer probe. The absorbed EC power is calculated considering also the polarization rotation and the subsequent mode conversion after incidence on the internal wall and compared with that derived from experimental data. The resulting EC power distribution can explain differences observed between perpendicular and oblique injection results, indicating future investigations to define ITER power requirements.

Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Ballenthin, J. O.; Baumgardner, J. L.; Bhatt, A.; Boyd, I. D.; Burt, J. M.; Caton, R. G.; Coster, A.; Erickson, P. J.; Huba, J. D.;

Relativistic nonlinear plasma waves in a magnetic field

NASA Technical Reports Server (NTRS)

Kennel, C. F.; Pellat, R.

1975-01-01

Five relativistic plane nonlinear waves were investigated: circularly polarized waves and electrostatic plasma oscillations propagating parallel to the magnetic field, relativistic Alfven waves, linearly polarized transverse waves propagating in zero magnetic field, and the relativistic analog of the extraordinary mode propagating at an arbitrary angle to the magnetic field. When the ions are driven relativistic, they behave like electrons, and the assumption of an 'electron-positron' plasma leads to equations which have the form of a one-dimensional potential well. The solutions indicate that a large-amplitude superluminous wave determines the average plasma properties.

Freak waves in negative-ion plasmas: an experiment revisited

NASA Astrophysics Data System (ADS)

Kourakis, Ioannis; Elkamash, Ibrahem; Reville, Brian

2016-10-01

Extreme events in the form of rogue waves (freak waves) occur widely in the open sea. These are space- and time-localised excitations, which appear unexpectedly and are characterised by a significant amplitude. Beyond ocean dynamics, the mechanisms underlying rogue wave formation are now being investigated in various physical contexts, including materials science, nonlinear optics and plasma physics, to mention but a few. We have undertaken an investigation, from first principles, of the occurrence of rogue waves associated with the propagation of electrostatic wavepackets in plasmas. Motivated by recent experimental considerations involving freak waves in negative-ion plasmas (NIP), we have addresed the occurrence of freak waves in NIP from first principles. An extended range of plasma parameter values was identified, where freak wave formation is possible, in terms of relevant plasma parameters. Our results extend -and partly contradict- the underlying assumptions in the interpretation of the aforementioned experiment, where a critical plasma configuration was considered and a Gardner equation approach was adopted. This work was supported from CPP/QUB funding. One of us (I. Elkamash) acknowledges financial support by an Egyptian Government fellowship.

Numerical and Experimental Investigation on the Attenuation of Electromagnetic Waves in Unmagnetized Plasmas Using Inductively Coupled Plasma Actuator

NASA Astrophysics Data System (ADS)

Lin, Min; Xu, Haojun; Wei, Xiaolong; Liang, Hua; Song, Huimin; Sun, Quan; Zhang, Yanhua

2015-10-01

The attenuation of electromagnetic (EM) waves in unmagnetized plasma generated by an inductively coupled plasma (ICP) actuator has been investigated both theoretically and experimentally. A numerical study is conducted to investigate the propagation of EM waves in multilayer plasma structures which cover a square flat plate. Experimentally, an ICP actuator with dimensions of 20 cm×20 cm×4 cm is designed to produce a steady plasma slab. The attenuation of EM waves in the plasma generated by the ICP actuator is measured by a reflectivity arch test method at incident waves of 2.3 GHz and 10.1 GHz, respectively. A contrastive analysis of calculated and measured results of these incident wave frequencies is presented, which suggests that the experiment accords well with our theory. As expected, the plasma slab generated by the ICP actuator can effectively attenuate the EM waves, which may have great potential application prospects in aircraft stealth. supported by National Natural Science Foundation of China (Nos. 51276197, 11472306 and 11402301)

Flowing Magnetized Plasma experiment

NASA Astrophysics Data System (ADS)

Wang, Zhehui; Si, Jiahe

2006-10-01

Results from the Flowing Magnetized Plasma experiment at Los Alamos are summarized. Plasmas are produced using a modified coaxial plasma gun with a center electrode extending into a cylindrical vacuum tank with 0.75 m in radius and 4.5 m long. The basic diagnostics are Bdot probes for edge and internal magnetic field, Mach probes and Doppler spectroscopy for plasma flow in the axial and azimuthal directions, and Langmuir probes for plasma floating potential, electron density and temperature. We have found two different plasma flow patterns associated with distinct IV characteristics of the coaxial plasma gun, indicating axial flow is strongly correlated with the plasma ejection from the plasma gun. Global electromagnetic oscillations at frequencies below ion cyclotron frequency are observed, indicating that familiar waves at these frequencies, e.g. Alfven wave or drift wave, are strongly modified by the finite plasma beta. We eliminate the possibility of ion sound waves since the ion and electron temperatures are comparable, and therefore, ion sound waves are strongly Landau damped.

Principles of Space Plasma Wave Instrument Design

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

1998-01-01

Space plasma waves span the frequency range from somewhat below the ion cyclotron frequency to well above the electron cyclotron frequency and plasma frequency. Because of the large frequency range involved, the design of space plasma wave instrumentation presents many interesting challenges. This chapter discusses the principles of space plasma wave instrument design. The topics covered include: performance requirements, electric antennas, magnetic antennas, and signal processing. Where appropriate, comments are made on the likely direction of future developments.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalaee, Mohammad Javad, E-mail: mjkalaee@ut.ac.ir; Katoh, Yuto, E-mail: yuto@stpp.gp.tohoku.ac.jp

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 wavesmore » (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.« less

Parametric amplification of a superconducting plasma wave

DOE PAGES

Rajasekaran, S.; Casandruc, E.; Laplace, Y.; ...

2016-07-11

Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor–metal oscillations and soliton formation. In this paper, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Finally, parametric amplification is sensitivemore » to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.« less

Plasma waves near saturn: initial results from voyager 1.

PubMed

Gurnett, D A; Kurth, W S; Scarf, F L

1981-04-10

The Voyager 1 plasma wave instrument detected many familiar types of plasma waves during the encounter with Saturn, including ion-acoustic waves and electron plasma oscillations upstream of the bow shock, an intense burst of electrostatic noise at the shock, and chorus, hiss, electrostatic electron cyclotron waves, and upper hybrid resonance emissions in the inner magnetosphere. A clocklike Saturn rotational control of low-frequency radio emissions was observed, and evidence was obtained of possible control by the moon Dione. Strong plasma wave emissions were detected at the Titan encounter indicating the presence of a turbulent sheath extending around Titan, and upper hybrid resonance measurements of the electron density show the existence of a dense plume of plasma being carried downstream of Titan by the interaction with the rapidly rotating magnetosphere of Saturn.

Nonlinear interactions between electromagnetic waves and electron plasma oscillations in quantum plasmas.

PubMed

Shukla, P K; Eliasson, B

2007-08-31

We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger equations and Poisson's equation. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma. The relevance of our investigation to the next generation intense laser-solid density plasma interaction experiments is discussed.

Characteristic analysis of surface waves in a sensitive plasma absorption probe

NASA Astrophysics Data System (ADS)

You, Wei; Li, Hong; Tan, Mingsheng; Liu, Wandong

2018-01-01

With features that are simple to construct and a symmetric configuration, the sensitive plasma absorption probe (SPAP) is a dependable probe for industry plasma diagnosis. The minimum peak in the characteristic curve of the coefficient of reflection stems from the surface wave resonance in plasma. We use numerical simulation methods to analyse the details of the excitation and propagation of these surface waves. With this method, the electromagnetic field structure and the resonance and propagation characteristics of the surface wave were analyzed simultaneously using the simulation method. For this SPAP structure, there are three different propagation paths for the propagating plasma surface wave. The propagation characteristic of the surface wave along each path is presented. Its dispersion relation is also calculated. The objective is to complete the relevant theory of the SPAP as well as the propagation process of the plasma surface wave.

Electron Beam Transport in Advanced Plasma Wave Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Ronald L

2013-01-31

The primary goal of this grant was to develop a diagnostic for relativistic plasma wave accelerators based on injecting a low energy electron beam (5-50keV) perpendicular to the plasma wave and observing the distortion of the electron beam's cross section due to the plasma wave's electrostatic fields. The amount of distortion would be proportional to the plasma wave amplitude, and is the basis for the diagnostic. The beat-wave scheme for producing plasma waves, using two CO2 laser beam, was modeled using a leap-frog integration scheme to solve the equations of motion. Single electron trajectories and corresponding phase space diagrams weremore » generated in order to study and understand the details of the interaction dynamics. The electron beam was simulated by combining thousands of single electrons, whose initial positions and momenta were selected by random number generators. The model was extended by including the interactions of the electrons with the CO2 laser fields of the beat wave, superimposed with the plasma wave fields. The results of the model were used to guide the design and construction of a small laboratory experiment that may be used to test the diagnostic idea.« less

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 ).

Excitation of Ion Acoustic Waves in Plasmas with Electron Emission from Walls

NASA Astrophysics Data System (ADS)

Khrabrov, A. V.; Wang, H.; Kaganovich, I. D.; Raitses, Y.; Sydorenko, D.

2015-11-01

Various plasma propulsion devices exhibit strong electron emission from the walls either as a result of secondary processes or due to thermionic emission. To understand details of electron kinetics in plasmas with strong emission, we have performed kinetic simulations of such plasmas using EDIPIC code. We show that excitation of ion acoustic waves is ubiquitous phenomena in many different plasma configurations with strong electron emission from walls. Ion acoustic waves were observed to be generated near sheath if the secondary electron emission from the walls is strong. Ion acoustic waves were also observed to be generated in the plasma bulk due to presence of an intense electron beam propagating from the cathode. This intense electron beam can excite strong plasma waves, which in turn drive the ion acoustic waves. Research supported by the U.S. Air Force Office of Scientific Research.

Modeling of helicon wave propagation and the physical process of helicon plasma production

NASA Astrophysics Data System (ADS)

Isayama, Shogo; Hada, Tohru; Shinohara, Shunjiro; Tanikawa, Takao

2014-10-01

Helicon plasma is a high-density and low-temperature plasma generated by the helicon wave, and is expected to be useful for various applications. On the other hand, there still remain a number of unsolved physical issues regarding how the plasma is generated using the helicon wave. The generation involves such physical processes as wave propagation, mode conversion, and collisionless as well as collisional wave damping that leads to ionization/recombination of neutral particles. In this study, we attempt to construct a model for the helicon plasma production using numerical simulations. In particular, we will make a quantitative argument on the roles of the mode conversion from the helicon to the electrostatic Trivelpiece-Gould (TG) wave, as first proposed by Shamrai. According to his scenario, the long wavelength helicon wave linearly mode converts to the TG wave, which then dissipates rapidly due to its large wave number. On the other hand, the efficiency of the mode conversion depends strongly on the magnitudes of dissipation parameters. Particularly when the dissipation is dominant, the TG wave is no longer excited and the input helicon wave directly dissipates. In the presentation, we will discuss the mode conversion and the plasma heating using numerical simulations.

Measurements of Mode Converted Ion Cyclotron Wave with Phase Contrast Imaging in Alcator C-Mod and Comparisons with Synthetic PCI Simulations in TORIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsujii, N.; Porkolab, M.; Edlund, E. M.

2009-11-26

Mode converted ion cyclotron wave (ICW) has been observed with phase contrast imaging (PCI) in D-{sup 3}He plasmas in Alcator C-Mod. The measurements were carried out with the optical heterodyne technique using acousto-optic modulators which modulate the CO2 laser beam intensity near the ion cyclotron frequency. With recently improved calibration of the PCI system using a calibrated sound wave source, the measurements have been compared with the full-wave code TORIC, as interpreted by a synthetic diagnostic. Because of the line-integrated nature of the PCI signal, the predictions are sensitive to the exact wave field pattern. The simulations are found tomore » be in qualitative agreement with the measurements.« less

Kinetic treatment of nonlinear ion-acoustic waves in multi-ion plasma

NASA Astrophysics Data System (ADS)

Ahmad, Zulfiqar; Ahmad, Mushtaq; Qamar, A.

2017-09-01

By applying the kinetic theory of the Valsove-Poisson model and the reductive perturbation technique, a Korteweg-de Vries (KdV) equation is derived for small but finite amplitude ion acoustic waves in multi-ion plasma composed of positive and negative ions along with the fraction of electrons. A correspondent equation is also derived from the basic set of fluid equations of adiabatic ions and isothermal electrons. Both kinetic and fluid KdV equations are stationary solved with different nature of coefficients. Their differences are discussed both analytically and numerically. The criteria of the fluid approach as a limiting case of kinetic theory are also discussed. The presence of negative ion makes some modification in the solitary structure that has also been discussed with its implication at the laboratory level.

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

NASA Astrophysics Data System (ADS)

Grishkov, V. E.; Uryupin, S. A.

2017-03-01

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron-ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

On a theory of surface waves in a smoothly inhomogeneous plasma in an external magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuzelev, M. V., E-mail: kuzelev@mail.ru; Orlikovskaya, N. G.

2016-12-15

A theory of surface waves in a magnetoactive plasma with smooth boundaries has been developed. A dispersion equation for surface waves has been derived for a linear law of density change at the plasma boundary. The frequencies of surface waves and their collisionless damping rates have been determined. A generalization to an arbitrary density profile at the plasma boundary is given. The collisions have been taken into account, and the application of the Landau rule in the theory of surface wave damping in a spatially inhomogeneous magnetoactive collisional plasma has been clarified.

Trivelpiece-Gould modes in a uniform unbounded plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stenzel, R. L.; Urrutia, J. M.

Trivelpiece-Gould (TG) modes originally described electrostatic surface waves on an axially magnetized cylindrical plasma column. Subsequent studies of electromagnetic waves in such plasma columns revealed two modes, a predominantly magnetic helicon mode (H) and the mixed magnetic and electrostatic Trivelpiece-Gould modes (TG). The latter are similar to whistler modes near the oblique cyclotron resonance in unbounded plasmas. The wave propagation in cylindrical geometry is assumed to be paraxial while the modes exhibit radial standing waves. The present work shows that TG modes also arise in a uniform plasma without radial standing waves. It is shown experimentally that oblique cyclotron resonancemore » arises in large mode number helicons. Their azimuthal wave number far exceeds the axial wave number which creates whistlers near the oblique cyclotron resonance. Cyclotron damping absorbs the TG mode and can energize electrons in the center of a plasma column rather than the edge of conventional TG modes. The angular orbital field momentum can produce new perpendicular wave-particle interactions.« less

Influence of nonlinear detuning at plasma wavebreaking threshold on backward Raman compression of non-relativistic laser pulses

NASA Astrophysics Data System (ADS)

Balakin, A. A.; Fraiman, G. M.; Jia, Q.; Fisch, N. J.

2018-06-01

Taking into account the nonlinear dispersion of the plasma wave, the fluid equations for the three-wave (Raman) interaction in plasmas are derived. It is found that, in some parameter regimes, the nonlinear detuning resulting from the plasma wave dispersion during Raman compression limits the plasma wave amplitude to noticeably below the generally recognized wavebreaking threshold. Particle-in-cell simulations confirm the theoretical estimates. For weakly nonlinear dispersion, the detuning effect can be counteracted by pump chirping or, equivalently, by upshifting slightly the pump frequency, so that the frequency-upshifted pump interacts with the seed at the point where the plasma wave enters the nonlinear stage.

Estimation of HF artificial ionospheric turbulence characteristics using comparison of calculated plasma wave decay rates with the measured decay rates of the stimulated electromagnetic emission

NASA Astrophysics Data System (ADS)

Bareev, D. D.; Gavrilenko, V. G.; Grach, S. M.; Sergeev, E. N.

2016-02-01

It is shown experimentally that the relaxation time of the stimulated electromagnetic emission (SEE) after the pump wave turn off decreases when frequency of the electromagnetic wave, responsible for the SEE generation (pump wave f0 or diagnostic wave fdw) approaches 4th harmonic of the electron cyclotron frequency fce . Since the SEE relaxation is determined by the damping rate of plasma waves with the same frequency, responsible for the SEE generation, we calculated damping rates of plasma waves with ω ∼ωuh (ω is the plasma wave frequency, ωuh is the upper hybrid frequency) for frequencies close to and distant from the double resonance where ωuh ∼ 4ωce (ωce = 2 πfce). The calculations were performed numerically on the base of linear plasma wave dispersion relation at arbitrary ratio between | Δ | = ω - 4ωce and |k‖ |VTe (VTe is the electron thermal speed and k‖ is the projection of the wave vector onto the magnetic field direction. A comparison of calculation and experimental results has shown that obtained frequency dependence of the SEE decay rate is similar to the damping rate frequency dependence for plasma waves with wave vectors directed at the angles 60-70° to the magnetic field, and gives a strong hint that oblique upper hybrid plasma waves should be responsible for the SEE generation.

General Notions on Macroscopic Theory of Waves in Plasmas; NOTIONS GENERALES SUR LA THEORIE MACROSCOPIQUE DES ONDES DANS LES PLASMAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allis, W.P.; Delcroix, J.L.

1963-01-01

The propagation of monochromatic plane waves in an indefinite plasma is treated in the hydrodynamic theory of two fluids. Plasmas with isotropic pressure and waves obeying exact adiabaticity are considered. (D.C.W.)

Laser mode conversion into a surface plasma wave in a metal coated optical fiber

NASA Astrophysics Data System (ADS)

Liu, C. S.; Kumar, Gagan; Tripathi, V. K.

2006-07-01

An optical fiber, coated with thin metal film, supports two distinct kinds of waves, viz., body waves that propagate through the fiber as transverse magnetic (TM) and transverse electric modes, and surface plasma waves that propagate on metal free space interface. When the metal has a ripple of suitable wave number q, a body wave of frequency ω and propagation constant kz induces a current at ω ,kz+q in the ripple region that resonantly derives a surface plasma wave. When the metal surface has metallic particles attached to it and molecules are adsorbed on them, the surface plasma wave undergoes surface enhanced Raman scattering with them. The scattered signals propagate backward as a TM body wave and can be detected.

Dynamics of Quasi-Electrostatic Whistler waves in Earth's Radiation belts

NASA Astrophysics Data System (ADS)

Goyal, R.; Sharma, R. P.; Gupta, D. N.

2017-12-01

A numerical model is proposed to study the dynamics of high amplitude quasi-electrostatic whistler waves propagating near resonance cone angle and their interaction with finite frequency kinetic Alfvén waves (KAWs) in Earth's radiation belts. The quasi-electrostatic character of whistlers is narrated by dynamics of wave propagating near resonance cone. A high amplitude whistler wave packet is obtained using the present analysis which has also been observed by S/WAVES instrument onboard STEREO. The numerical simulation technique employed to study the dynamics, leads to localization (channelling) of waves as well as turbulent spectrum suggesting the transfer of wave energy over a range of frequencies. The turbulent spectrum also indicates the presence of quasi-electrostatic whistlers and density fluctuations associated with KAW in radiation belts plasma. The ponderomotive force of pump quasi-electrostatic whistlers (high frequency) is used to excite relatively much lower frequency waves (KAWs). The wave localization and steeper spectra could be responsible for particle energization or heating in radiation belts.

Temperature of the plasmasphere from Van Allen Probes HOPE

NASA Astrophysics Data System (ADS)

Genestreti, K. J.; Goldstein, J.; Corley, G. D.; Farner, W.; Kistler, L. M.; Larsen, B. A.; Mouikis, C. G.; Ramnarace, C.; Skoug, R. M.; Turner, N. E.

2017-01-01

We introduce two novel techniques for estimating temperatures of very low energy space plasmas using, primarily, in situ data from an electrostatic analyzer mounted on a charged and moving spacecraft. The techniques are used to estimate proton temperatures during intervals where the bulk of the ion plasma is well below the energy bandpass of the analyzer. Both techniques assume that the plasma may be described by a one-dimensional E→×B→ drifting Maxwellian and that the potential field and motion of the spacecraft may be accounted for in the simplest possible manner, i.e., by a linear shift of coordinates. The first technique involves the application of a constrained theoretical fit to a measured distribution function. The second technique involves the comparison of total and partial-energy number densities. Both techniques are applied to Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) observations of the proton component of the plasmasphere during two orbits on 15 January 2013. We find that the temperatures calculated from these two order-of-magnitude-type techniques are in good agreement with typical ranges of the plasmaspheric temperature calculated using retarding potential analyzer-based measurements—generally between 0.2 and 2 eV (2000-20,000 K). We also find that the temperature is correlated with L shell and hot plasma density and is negatively correlated with the cold plasma density. We posit that the latter of these three relationships may be indicative of collisional or wave-driven heating of the plasmasphere in the ring current overlap region. We note that these techniques may be easily applied to similar data sets or used for a variety of purposes.

Ionization Waves of Arbitrary Velocity

NASA Astrophysics Data System (ADS)

Turnbull, D.; Franke, P.; Katz, J.; Palastro, J. P.; Begishev, I. A.; Boni, R.; Bromage, J.; Milder, A. L.; Shaw, J. L.; Froula, D. H.

2018-06-01

Flying focus is a technique that uses a chirped laser beam focused by a highly chromatic lens to produce an extended focal region within which the peak laser intensity can propagate at any velocity. When that intensity is high enough to ionize a background gas, an ionization wave will track the intensity isosurface corresponding to the ionization threshold. We report on the demonstration of such ionization waves of arbitrary velocity. Subluminal and superluminal ionization fronts were produced that propagated both forward and backward relative to the ionizing laser. All backward and all superluminal cases mitigated the issue of ionization-induced refraction that typically inhibits the formation of long, contiguous plasma channels.

Drift-Alfven wave mediated particle transport in an elongated density depression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vincena, Stephen; Gekelman, Walter

Cross-field particle transport due to drift-Alfven waves is measured in an elongated density depression within an otherwise uniform, magnetized helium plasma column. The depression is formed by drawing an electron current to a biased copper plate with cross-field dimensions of 28x0.24 ion sound-gyroradii {rho}{sub s}=c{sub s}/{omega}{sub ci}. The process of density depletion and replenishment via particle flux repeats in a quasiperiodic fashion for the duration of the current collection. The mode structure of the wave density fluctuations in the plane perpendicular to the background magnetic field is revealed using a two-probe correlation technique. The particle flux as a function ofmore » frequency is measured using a linear array of Langmuir probes and the only significant transport occurs for waves with frequencies between 15%-25% of the ion cyclotron frequency (measured in the laboratory frame) and with perpendicular wavelengths k{sub perpendicular}{rho}{sub s}{approx}0.7. The frequency-integrated particle flux is in rough agreement with observed increases in density in the center of the depletion as a function of time. The experiments are carried out in the Large Plasma Device (LAPD) [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at the Basic Plasma Science Facility located at the University of California, Los Angeles.« less

The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588

2016-05-15

The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-chargemore » wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.« less

Wave excitation by nonlinear coupling among shear Alfvén waves in a mirror-confined plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikezoe, R., E-mail: ikezoe@prc.tsukuba.ac.jp; Ichimura, M.; Okada, T.

2015-09-15

A shear Alfvén wave at slightly below the ion-cyclotron frequency overcomes the ion-cyclotron damping and grows because of the strong anisotropy of the ion temperature in the magnetic mirror configuration, and is called the Alfvén ion-cyclotron (AIC) wave. Density fluctuations caused by the AIC waves and the ion-cyclotron range of frequencies (ICRF) waves used for ion heating have been detected using a reflectometer in a wide radial region of the GAMMA 10 tandem mirror plasma. Various wave-wave couplings are clearly observed in the density fluctuations in the interior of the plasma, but these couplings are not so clear in themore » magnetic fluctuations at the plasma edge when measured using a pick-up coil. A radial dependence of the nonlinearity is found, particularly in waves with the difference frequencies of the AIC waves; bispectral analysis shows that such wave-wave coupling is significant near the core, but is not so evident at the periphery. In contrast, nonlinear coupling with the low-frequency background turbulence is quite distinct at the periphery. Nonlinear coupling associated with the AIC waves may play a significant role in the beta- and anisotropy-limits of a mirror-confined plasma through decay of the ICRF heating power and degradation of the plasma confinement by nonlinearly generated waves.« less

First observation of the anomalous electric field in the topside ionosphere by ionospheric modification over EISCAT

NASA Astrophysics Data System (ADS)

Kosch, M. J.; Vickers, H.; Ogawa, Y.; Senior, A.; Blagoveshchenskaya, N.

2014-11-01

We have developed an active ground-based technique to estimate the steady state field-aligned anomalous electric field (E*) in the topside ionosphere, up to ~600 km, using the European Incoherent Scatter (EISCAT) ionospheric modification facility and UHF incoherent scatter radar. When pumping the ionosphere with high-power high-frequency radio waves, the F region electron temperature is significantly raised, increasing the plasma pressure gradient in the topside ionosphere, resulting in ion upflow along the magnetic field line. We estimate E* using a modified ion momentum equation and the Mass Spectrometer Incoherent Scatter model. From an experiment on 23 October 2013, E* points downward with an average amplitude of ~1.6 μV/m, becoming weaker at higher altitudes. The mechanism for anomalous resistivity is thought to be low-frequency ion acoustic waves generated by the pump-induced flux of suprathermal electrons. These high-energy electrons are produced near the pump wave reflection altitude by plasma resonance and also result in observed artificially induced optical emissions.

Effects of transport coefficients on excitation of flare-induced standing slow-mode waves

NASA Astrophysics Data System (ADS)

Wang, Tongjiang; Ofman, Leon; Davila, Joseph

2017-08-01

The flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA, and interpreted as the slow-mode standing waves. By means of the seismology technique we have, for the first time, determined the transport coefficients in the hot (>9 MK) flare plasma, and found that thermal conductivity is suppressed by at least 3 times and viscosity coefficient is enhanced by a factor of 15 as the upper limit (Wang et al. 2015, ApJL, 811, L13). In this presentation, we first discuss possible causes for conduction suppression and viscosity enhancements. Then we use the nonlinear MHD simulations to validate the seismology method that is based on linear analytical analysis, and demonstrate the inversion scheme for determining transport coefficients using numerical parametric study. Finally, we show how the seismologically-determined transport coefficients are crucial for understanding the excitation of the observed standing slow-mode waves in coronal loops and the heating of the loop plasma by a footpoint flare.

Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru

The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs–Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wavemore » effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm{sup 2} in the Ka-band and about 200 μJ/cm{sup 2} in the D-band have been demonstrated.« less

First density profile measurements using frequency modulation of the continuous wave reflectometry on JETa)

NASA Astrophysics Data System (ADS)

Meneses, L.; Cupido, L.; Sirinelli, A.; Manso, M. E.; Jet-Efds Contributors

2008-10-01

We present the main design options and implementation of an X-mode reflectometer developed and successfully installed at JET using an innovative approach. It aims to prove the viability of measuring density profiles with high spatial and temporal resolution using broadband reflectometry operating in long and complex transmission lines. It probes the plasma with magnetic fields between 2.4 and 3.0 T using the V band [~(0-1.4)×1019 m-3]. The first experimental results show the high sensitivity of the diagnostic when measuring changes in the plasma density profile occurring ITER relevant regimes, such as ELMy H-modes. The successful demonstration of this concept motivated the upgrade of the JET frequency modulation of the continuous wave (FMCW) reflectometry diagnostic, to probe both the edge and core. This new system is essential to prove the viability of using the FMCW reflectometry technique to probe the plasma in next step devices, such as ITER, since they share the same waveguide complexity.

Plasma wave excitation by intense microwave transmission from a space vehicle

NASA Astrophysics Data System (ADS)

Kimura, I.; Matsumoto, H.; Kaya, N.; Miyatake, S.

An impact of intense microwave upon the ionospheric plasma was empirically investigated by an active rocket experiment (MINIX). The rocket carried two high-power (830W) transmitters of 2.45 GHz microwave on the mother section of the rocket. The ionospheric plasma response to the intense microwave was measured by a diagnostic package installed on both mother and daughter sections. The daughter section was separated from the mother with a slow speed of 15 cm/sec. The plasma wave analyzers revealed that various plasma waves are nonlinearly excited by the microwave. Among them, the most intense are electron cyclotron waves, followed by electron plasma waves. Extremely low frequency waves (several tens of Hz) are also found. The results of the data analysis as well as comparative computer simulations are given in this paper.

Plasma waves near Saturn: initial results from Voyager 1. Progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurnett, D.A.; Kurth, W.S.; Scarf, F.L.

1981-01-31

The Voyager 1 plasma wave instrument detected many familiar types of plasma waves during the encounter with Saturn, including ion-acoustic waves and electron plasma oscillations upstream of the bow shock, an intense burst of electrostatic noise at the shock, and chorus, hiss, electrostatic (n + 1/2)fg waves and UHR emissions in the inner magnetosphere. A clock-like Saturn rotational control of low-frequency radio emissions was observed, and evidence was obtained of possible control by the moon Dione. Strong plasma wave emissions were detected at the Titan encounter indicating the presence of a turbulent sheath extending around Titan, and UHR measurements ofmore » the electron density show the existence of a dense plume of plasma being carried downstream of Titan by the interaction with the rapidly rotating magnetosphere of Saturn.« less

The application of the constants of motion to nonlinear stationary waves in complex plasmas: a unified fluid dynamic viewpoint

NASA Astrophysics Data System (ADS)

McKenzie, J. F.; Dubinin, E.; Sauer, K.; Doyle, T. B.

2004-08-01

Perturbation reductive procedures, as used to analyse various weakly nonlinear plasma waves (solitons and periodic waves), normally lead to the dynamical system being described by KdV, Burgers' or a nonlinear Schrödinger-type equation, with properties that can be deduced from an array of mathematical techniques. Here we develop a fully nonlinear theory of one-dimensional stationary plasma waves, which elucidates the common nature of various diverse wave phenomena. This is accomplished by adopting an essentially fluid dynamic viewpoint. In this unified treatment the constants of the motion (for mass, momentum and energy) lead naturally to the construction of the wave structure equations. It is shown, for example, that electrostatic, Hall magnetohydrodynamic and ion cyclotron acoustic nonlinear waves all obey first-order differential equations of the same generic type for the longitudinal flow field of the wave. The equilibrium points, which define the soliton amplitude, are given by the compressive and/or rarefactive roots of a total plasma ‘energy’ or ‘momentum’ function characterizing the wave type. This energy function, which is an algebraic combination of the Bernoulli momentum and energy functions for the longitudinal flow field, is the fluid dynamic counterpart of the pseudo-potentials, which are characteristic of system structure equations formulated in other than fluid variables. Another general feature of the structure equation is the phenomenon of choked flow, which occurs when the flow speed becomes sonic. It is this trans-sonic property that limits the soliton amplitudes and defines the critical collective Mach numbers of the waves. These features are also obtained in multi-component plasmas where, for example, in a bi-ion plasma, momentum exchanges between protons and heavier ions are mediated by the Maxwell magnetic stresses. With a suitable generalization of the concept of a sonic point in a bi-ion system and the corresponding choked flow feature, the wave structures, although now more complicated, can also be understood within this overall fluid framework. Particularly useful tools in this context are the momentum hodograph (an algebraic relation between the bi-ion speeds and the electron speed, or magnetic field, which follows from the conservation of mass, momentum and charge-neutrality) and a generalized Bernoulli energy density for each species. Analysis shows that the bi-ion solitons are essentially compressive, but contain the remarkable feature of the presence of a proton rarefactive core. A new type of soliton, called an ‘oscilliton’ because embedded spatial oscillations are superimposed on the classical soliton, is also described and discussed. A necessary condition for the existence of this type of wave is that the linear phase velocity must exhibit an extremum where the phase speed matches the group speed. The remarkable properties of this wave are illustrated for the case of both whistler waves and bi-ion waves where, for the latter, the requisite condition is met near the cross-over frequencies. In the case of the whistler oscilliton, which propagates at speeds in excess of one half of the Alfvén speed (based on the electrons), an analytic solution has been constructed through a phase-portrait integral of the system in which the proton and electron dynamics must be placed on the same footing. The relevance of the different wave structures to diverse space environments is briefly discussed in relation to recently available high-time and spatial resolution data from satellite observations.

KEEN Wave Simulations: Comparing various PIC to various fixed grid Vlasov to Phase-Space Adaptive Sparse Tiling & Effective Lagrangian (PASTEL) Techniques

NASA Astrophysics Data System (ADS)

Afeyan, Bedros; Larson, David; Shadwick, Bradley; Sydora, Richard

2017-10-01

We compare various ways of solving the Vlasov-Poisson and Vlasov-Maxwell equations on rather demanding nonlinear kinetic phenomena associated with KEEN and KEEPN waves. KEEN stands for Kinetic, Electrostatic, Electron Nonlinear, and KEEPN, for electron-positron or pair plasmas analogs. Because these self-organized phase space structures are not steady-state, or single mode, or fluid or low order moment equation limited, typical techniques with low resolution or too much noise will distort the answer too much, too soon, and fail. This will be shown via Penrose criteria triggers for instability at the formation stage as well as particle orbit statistics in fully formed KEEN waves and KEEN-KEEN and KEEN-EPW interacting states. We will argue that PASTEL is a viable alternative to traditional methods with reasonable chances of success in higher dimensions. Work supported by a Grant from AFOSR PEEP.

Effect of a Dusty Layer on Surface-Wave Produced Plasmas

NASA Astrophysics Data System (ADS)

Ostrikov, Kostyantyn; Yu, Ming; Xu, Shuyan

2000-10-01

The effect of near-sheath dusts on the RF power loss in a surface-wave sustained gas discharge is studied. The planar plasma is bounded by a dielectric and consists of an inhomogeneous near-wall transition layer (sheath), a dusty plasma layer, and the outer dust-free plasma. The discharge is maintained by high-frequency axially-symmetric surface waves. The surface-wave power loss from the most relevant dissipative mechanisms in typical discharge plasmas is analyzed. Our model allows one to consider the main effects of dust particles on surface-wave produced discharge plasmas. We demonstrate that the dusts released in the discharge can strongly modify the plasma conductivity and lead to a significant redistribution of the total charge. They affect the electron quasi-momenta, but do not absorb the energy transmitted to the plasma through elastic collisions, and therefore they remain cold at the room temperature. It is shown that the improvement of the efficiency of energy transfer from the wave source to the plasma can be achieved by selecting operation regimes when the efficiency of the power loss in the plasma through electron-neutral collisions is higher than that through electron-dust interactions.

The big contradiction between the perturbation theory and the chaotic state. A detailed mathematical analysis indicates when the plasma is stable or unstable

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xaplanteris, C. L., E-mail: cxaplanteris@yahoo.com; Xaplanteris, S. C.

2016-05-15

In the present manuscript enough observations and interpretations of three issues of Plasma Physics are presented. The first issue is linked to the common experimental confirmation of plasma waves which appear to be repeated in a standard way while there are also cases where plasma waves change to an unstable state or even to chaotic state. The second issue is associated with a mathematical analysis of the movement of a charged particle using the perturbation theory; which could be used as a guide for new researchers on similar issues. Finally, the suitability and applicability of the perturbation theory or themore » chaotic theory is presented. Although this study could be conducted on many plasma phenomena (e.g. plasma diffusion) or plasma quantities (e.g. plasma conductivity), here it was decided this study to be conducted on plasma waves and particularly on drift waves. This was because of the significance of waves on the plasmatic state and especially their negative impact on the thermonuclear fusion, but also due to the long-time experience of the plasma laboratory of Demokritos on drift waves.« less

The effect of plasma inhomogeneities on (i) radio emission generation by non-gyrotropic electron beams and (ii) particle acceleration by Langmuir waves

NASA Astrophysics Data System (ADS)

Tsiklauri, D.

2014-12-01

Extensive particle-in-cell simulations of fast electron beams injected in a background magnetised plasma with a decreasing density profile were carried out. These simulations were intended to further shed light on a newly proposed mechanism for the generation of electromagnetic waves in type III solar radio bursts [1]. Here recent progress in an alternative to the plasma emission model using Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts will be presented. In particular, (i) Fourier space drift (refraction) of non-gyrotropic electron beam-generated wave packets, caused by the density gradient [1,2], (ii) parameter space investigation of numerical runs [3], (iii) concurrent generation of whistler waves [4] and a separate problem of (iv) electron acceleration by Langmuir waves in a background magnetised plasma with an increasing density profile [5] will be discussed. In all considered cases the density inhomogeneity-induced wave refraction plays a crucial role. In the case of non-gyrotropic electron beam, the wave refaction transforms the generated wave packets from standing into freely escaping EM radiation. In the case of electron acceleration by Langmuir waves, a positive density gradient in the direction of wave propagation causes a decrease in the wavenumber, and hence a higher phase velocity vph=ω/k. The k-shifted wave is then subject to absorption by a faster electron by wave-particle interaction. The overall effect is an increased number of high energy electrons in the energy spectrum. [1] D. Tsiklauri, Phys. Plasmas 18, 052903 (2011) [2] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013) [3] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012) [4] M. Skender, D. Tsiklauri, Phys. Plasmas 21, 042904 (2014) [5] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 21, 012903 (2014)

High-frequency plasma-heating apparatus

DOEpatents

Brambilla, Marco; Lallia, Pascal

1978-01-01

An array of adjacent wave guides feed high-frequency energy into a vacuum chamber in which a toroidal plasma is confined by a magnetic field, the wave guide array being located between two toroidal current windings. Waves are excited in the wave guide at a frequency substantially equal to the lower frequency hybrid wave of the plasma and a substantially equal phase shift is provided from one guide to the next between the waves therein. For plasmas of low peripheral density gradient, the guides are excited in the TE.sub.01 mode and the output electric field is parallel to the direction of the toroidal magnetic field. For exciting waves in plasmas of high peripheral density gradient, the guides are excited in the TM.sub.01 mode and the magnetic field at the wave guide outlets is parallel to the direction of the toroidal magnetic field. The wave excited at the outlet of the wave guide array is a progressive wave propagating in the direction opposite to that of the toroidal current and is, therefore, not absorbed by so-called "runaway" electrons.

Electromagnetic plasma wave propagation along a magnetic field. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Olson, C. L.

1970-01-01

The linearized response of a Vlasov plasma to the steady-state excitation of transverse plasma waves along an external magnetic field is examined. Assuming a delta-function excitation mechanism, and performing a detailed Vlasov-Maxwell equation analysis using Fourier-Laplace transforms, the plasma response is found to consist of three terms: a branch-cut term, a free-streaming term, and a dielectric-pole term. Also considered is the phenomenon of plasma wave echoes. The case of longitudinal electrostatic waves is extended to the case of transverse plasma waves that propagate along an external magnetic field. It is shown that a transverse echo results in lowest order only when one excitation is transverse and the other is longitudinal.

Electrostatic lower hybrid waves excited by electromagnetic whistler mode waves scattering from planar magnetic-field-aligned plasma density irregularities

NASA Technical Reports Server (NTRS)

Bell, T. F.; Ngo, H. D.

1990-01-01

This paper presents a theoretical model for electrostatic lower hybrid waves excited by electromagnetic whistler mode waves propagating in regions of the magnetosphere and the topside ionosphere, where small-scale magnetic-field-aligned plasma density irregularities are thought to exist. In this model, the electrostatic waves are excited by linear mode coupling as the incident electromagnetic whistler mode waves scatter from the magnetic-field-aligned plasma density irregularities. Results indicate that high-amplitude short-wavelength (5 to 100 m) quasi-electrostatic whistler mode waves can be excited when electromagnetic whistler mode waves scatter from small-scale planar magnetic-field-aligned plasma density irregularities in the topside ionosphere and magnetosphere.

Plasma wave phenomena at interplanetary shocks observed by the Ulysses URAP experiment. [Unified Radio and Plasma Waves

NASA Technical Reports Server (NTRS)

Lengyel-Frey, D.; Macdowall, R. J.; Stone, R. G.; Hoang, S.; Pantellini, F.; Harvey, C.; Mangeney, A.; Kellogg, P.; Thiessen, J.; Canu, P.

1992-01-01

We present Ulysses URAP observations of plasma waves at seven interplanetary shocks detected between approximately 1 and 3 AU. The URAP data allows ready correlation of wave phenomena from .1 Hz to 1 MHz. Wave phenomena observed in the shock vicinity include abrupt changes in the quasi-thermal noise continuum, Langmuir wave activity, ion acoustic noise, whistler waves and low frequency electrostatic waves. We focus on the forward/reverse shock pair of May 27, 1991 to demonstrate the characteristics of the URAP data.

Diagnosing collisionless energy transfer using field-particle correlations: Vlasov-Poisson plasmas

NASA Astrophysics Data System (ADS)

Howes, Gregory G.; Klein, Kristopher G.; Li, Tak Chu

2017-02-01

Turbulence plays a key role in the conversion of the energy of large-scale fields and flows to plasma heat, impacting the macroscopic evolution of the heliosphere and other astrophysical plasma systems. Although we have long been able to make direct spacecraft measurements of all aspects of the electromagnetic field and plasma fluctuations in near-Earth space, our understanding of the physical mechanisms responsible for the damping of the turbulent fluctuations in heliospheric plasmas remains incomplete. Here we propose an innovative field-particle correlation technique that can be used to measure directly the secular energy transfer from fields to particles associated with collisionless damping of the turbulent fluctuations. Furthermore, this novel procedure yields information about the collisionless energy transfer as a function of particle velocity, providing vital new information that can help to identify the dominant collisionless mechanism governing the damping of the turbulent fluctuations. Kinetic plasma theory is used to devise the appropriate correlation to diagnose Landau damping, and the field-particle correlation technique is thoroughly illustrated using the simplified case of the Landau damping of Langmuir waves in a 1D-1V (one dimension in physical space and one dimension in velocity space) Vlasov-Poisson plasma. Generalizations necessary to apply the field-particle correlation technique to diagnose the collisionless damping of turbulent fluctuations in the solar wind are discussed, highlighting several caveats. This novel field-particle correlation technique is intended to be used as a primary analysis tool for measurements from current, upcoming and proposed spacecraft missions that are focused on the kinetic microphysics of weakly collisional heliospheric plasmas, including the Magnetospheric Multiscale (MMS), Solar Probe Plus, Solar Orbiter and Turbulence Heating ObserveR (THOR) missions.

Spectral properties of Langmuir and beam-mode waves observed inside terrestrial foreshock by Cluster spacecraf

NASA Astrophysics Data System (ADS)

Pisa, D.; Soucek, J.; Santolik, O.

2016-12-01

Electrostatic plasma waves are commonly observed in the upstream regions of planetary shocks. Solar wind electrons accelerated at the shock front are reflected back into the solar wind and form electron beams. The electron distribution becomes unstable and electrostatic waves are generated inside the foreshock region. The processes of generation and evolution of electrostatic waves significantly depend on the solar wind plasma conditions and generally exhibit complex behavior. Langmuir waves can be identified as intense narrowband emission at the local plasma frequency and weaker broadband beam-mode waves below and above the plasma frequency deeper in the downstream region. We present a long-term survey of Langmuir and beam-mode waves in the vicinity of the plasma frequency observed upstream of the terrestrial bow shock by the Cluster spacecraft. Using solar wind data and bow shock positions from OMNI, as well as in-situ measurements of interplanetary magnetic field, we have mapped all available spacecraft positions into foreshock coordinates. For a study of plasma waves, we have used spectra and local plasma frequencies obtained from a passive and active mode of the WHISPER instrument. We show a spatial distribution of wave frequencies and spectral widths as a function of foreshock positions and solar wind conditions.

Experiments on and observations of intense Alfvén waves in the laboratory

NASA Astrophysics Data System (ADS)

Gekelman, W.; Vanzeeland, M.; Vincena, S.

2002-11-01

There are many situations, which occur in space (coronal mass ejections, supernovas), or are man-made (upper atmospheric detonations) in which a dense plasma expands into a background magnetized plasma, that can support Alfvén waves. The LArge Plasma Device ( LAPD) is a machine, at UCLA, in which Alfvén wave propagation in homogeneous and inhomogeneous plasmas has been studied. We describe a series of experiments which involve the expansion of a dense (initially, n_lpp/n_0>>1) laser-produced plasma into an ambient highly magnetized background plasma capable of supporting Alfvén waves. The interaction results in the production of intense shear and compressional Alfvén waves, as well as large density perturbations. The magnetic fields of the waves are obtained with a 3-axis inductive probe. Spatial patterns of the magnetic fields associated with the waves and density perturbations are measured at over 10^4 locations. The wave generation mechanism is due to currents from fast electrons which leave the lpp and field aligned return currents provided by the plasma to neutralize space charge. Dramatic movies of the measured wave fields and their associated currents will be presented. *Work supported by the ONR, and DOE/NSF.

Fundamental mode of ultra-low frequency electrostatic dust-cyclotron surface waves in a magnetized complex plasma with drifting ions

NASA Astrophysics Data System (ADS)

Lee, Seungjun; Lee, Myoung-Jae

2012-10-01

The electrostatic dust-cyclotron (EDC) waves in a magnetized dusty plasma was reported that they could be excited by gravity in a collisional plasma [1]. Rosenberg suggested that EDC waves could be excited by ions drifting along the magnetic field in a collisional plasma containing dust grains with large thermal speeds [2]. The existing investigations, however, focus on EDC volume waves in which the boundary effects are not considered. In this work, we attempt to obtain some physical results concerning the fundamental mode of EDC surface wave and the stability of wave by utilizing a kinetic method. The EDC surface wave is assumed to propagate along an external magnetic field at the interface between the plasma and the vacuum. The plasma is comprised of drifting ions flowing along an external magnetic field. To derive the growth rate of surface waves, we employ the specular reflection boundary conditions. The EDC surface wave is found to be unstable when the ion drift velocity is larger than the phase velocity of the wave. In addition, the wave becomes to be more unstable if dust particles carry more negative charges.[4pt] [1] N. D'Angelo, Phys. Lett. A 323, 445 (2004).[0pt] [2] M. Rosenberg, Phys. Scr. 82, 035505 (2010).

Study of plasma-based stable and ultra-wideband electromagnetic wave absorption for stealth application

NASA Astrophysics Data System (ADS)

Xuyang, CHEN; Fangfang, SHEN; Yanming, LIU; Wei, AI; Xiaoping, LI

2018-06-01

A plasma-based stable, ultra-wideband electromagnetic (EM) wave absorber structure is studied in this paper for stealth applications. The stability is maintained by a multi-layer structure with several plasma layers and dielectric layers distributed alternately. The plasma in each plasma layer is designed to be uniform, whereas it has a discrete nonuniform distribution from the overall view of the structure. The nonuniform distribution of the plasma is the key to obtaining ultra-wideband wave absorption. A discrete Epstein distribution model is put forward to constrain the nonuniform electron density of the plasma layers, by which the wave absorption range is extended to the ultra-wideband. Then, the scattering matrix method (SMM) is employed to analyze the electromagnetic reflection and absorption of the absorber structure. In the simulation, the validation of the proposed structure and model in ultra-wideband EM wave absorption is first illustrated by comparing the nonuniform plasma model with the uniform case. Then, the influence of various parameters on the EM wave reflection of the plasma are simulated and analyzed in detail, verifying the EM wave absorption performance of the absorber. The proposed structure and model are expected to be superior in some realistic applications, such as supersonic aircraft.

Charcateristics of Plasma Waves Excited During Gas Release and Plasma Injection Into The Ionosphere

NASA Astrophysics Data System (ADS)

Klos, Z.; Gdalevich, G. L.; Mikhailov, I.

Waves in broad frequency range are generated during the injection of fast plasma as well as release of neutral gas into ionosphere from the spacecraft. The excited wave modes depend on the environmental plasma parameters, geometry of injection as well as on the rate of ionisation of plasma in the stream. The neutral xenon gas was released from the board of the ACTIVE satellite (in 1989) and parallel with the release process the VLF as well as HF waves were diagnosed. On the other hand the xenon plasma from gun generator was injected into the ionosphere from the board of APEX satellite (in 1991) and also broad frequency range of emission was registered. In the present paper are compared the plasma waves characteristics observed in these two types of experiments.

Are ion acoustic waves supported by high-density plasmas in the Large Plasma Device (LaPD)?

NASA Astrophysics Data System (ADS)

Roycroft, Rebecca; Dorfman, Seth; Carter, Troy A.; Gekelman, Walter; Tripathi, Shreekrishna

2012-10-01

Ion acoustic waves are a type of longitudinal wave in a plasma, propagating though the motion of the ions. The wave plays a key role in a parametric decay process thought to be responsible for the spectrum of turbulence observed in the solar wind. In recent LaPD experiments aimed at studying this process, modes thought to be ion acoustic waves are strongly damped when the pump Alfven waves are turned off. This observation motivates an experiment focused on directly launching ion acoustic waves under similar conditions. Our first attempt to launch ion acoustic waves using a metal grid in the plasma was unsuccessful at high magnetic fields and densities due to electrons shorting out the bias applied between the grid and the wall. Results from a new device based on [1] to launch ion acoustic waves will be presented; this device will consist of a small chamber with a plasma source separated from the main chamber by two biased grids. The plasma created inside the small device will be held at a different potential from the main plasma; modulation of this difference should affect the ions, allowing ion acoustic waves to be launched and their properties compared to the prior LaPD experiments.[4pt] [1] W. Gekelman and R. L. Stenzel, Phys. Fluids 21, 2014 (1978).

Continuous Wave Ring-Down Spectroscopy Diagnostic for Measuring Argon Ion and Neutral Velocity Distribution Functions in a Helicon Plasma

NASA Astrophysics Data System (ADS)

McCarren, Dustin; Vandervort, Robert; Soderholm, Mark; Carr, Jerry, Jr.; Galante, Matthew; Magee, Richard; Scime, Earl

2013-10-01

Cavity Ring-Down Spectroscopy CRDS is a proven, ultra-sensitive, cavity enhanced absorption spectroscopy technique. When combined with a continuous wavelength (CW) diode laser that has a sufficiently narrow line width, the Doppler broadened absorption line, i.e., the velocity distribution functions (IVDFs), can be measured. Measurements of IVDFS can be made using established techniques, such as laser induced fluorescence (LIF). However, LIF suffers from the requirement that the initial state of the LIF sequence have a substantial density. This usually limits LIF to ions and atoms with large metastable state densities for the given plasma conditions. CW-CRDS is considerably more sensitive than LIF and can potentially be applied to much lower density populations of ion and atom states. In this work we present ongoing measurements of the CW-CRDS diagnostic and discuss the technical challenges of using CW-CRDS to make measurements in a helicon plasma.

Plasma Modes

NASA Astrophysics Data System (ADS)

Dubin, D. H. E.

This chapter explores several aspects of the linear electrostatic normal modes of oscillation for a single-species non-neutral plasma in a Penning trap. Linearized fluid equations of motion are developed, assuming the plasma is cold but collisionless, which allow derivation of the cold plasma dielectric tensor and the electrostatic wave equation. Upper hybrid and magnetized plasma waves in an infinite uniform plasma are described. The effect of the plasma surface in a bounded plasma system is considered, and the properties of surface plasma waves are characterized. The normal modes of a cylindrical plasma column are discussed, and finally, modes of spheroidal plasmas, and finite temperature effects on the modes, are briefly described.

Laser-hole boring into overdense plasmas measured with soft X-Ray laser probing

PubMed

Takahashi; Kodama; Tanaka; Hashimoto; Kato; Mima; Weber; Barbee; Da Silva LB

2000-03-13

A laser self-focused channel formation into overdense plasmas was observed using a soft x-ray laser probe system with a grid image refractometry (GIR) technique. 1.053 &mgr;m laser light with a 100 ps pulse duration was focused onto a preformed plasma at an intensity of 2x10(17) W/cm (2). Cross sections of the channel were obtained which show a 30 &mgr;m diameter in overdense plasmas. The channel width in the overdense region was kept narrow as a result of self-focusing. Conically diverging density ridges were also observed along the channel, indicating a Mach cone created by a shock wave due to the supersonic propagation of the channel front.

Interaction of an electromagnetic wave with a rapidly created spatially periodic plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, S.P.; Faith, J.

1997-08-01

The interaction of electromagnetic waves with rapidly created time-varying spatially periodic plasmas is studied. The numerical results of the collisionless case show that both frequency upshifted and frequency downshifted waves are generated. Moreover, the frequency downshifted waves are trapped by the plasma when the plasma frequency is larger than the wave frequency. The trapping has the effect of dramatically enhancing the efficiency of the frequency downshift conversion process, by accumulating incident wave energy during the plasma transition period. A theory based on the wave impedance of each Floquet mode of the periodic structure is formulated, incorporating with the collisional dampingmore » of the plasma. Such a theory explains the recent experimental observations [Faith, Kuo, and Huang, Phys. Rev. E {bold 55}, 1843 (1997)] where the frequency downshifted signals were detected repetitively with considerably enhanced spectral intensities while the frequency upshifted signals were missing. {copyright} {ital 1997} {ital The American Physical Society}« less

Scattering characteristics of electromagnetic waves in time and space inhomogeneous weakly ionized dusty plasma sheath

NASA Astrophysics Data System (ADS)

Guo, Li-xin; Chen, Wei; Li, Jiang-ting; Ren, Yi; Liu, Song-hua

2018-05-01

The dielectric coefficient of a weakly ionised dusty plasma is used to establish a three-dimensional time and space inhomogeneous dusty plasma sheath. The effects of scattering on electromagnetic (EM) waves in this dusty plasma sheath are investigated using the auxiliary differential equation finite-difference time-domain method. Backward radar cross-sectional values of various parameters, including the dust particle radius, charging frequency of dust particles, dust particle concentration, effective collision frequency, rate of the electron density variation with time, angle of EM wave incidence, and plasma frequency, are analysed within the time and space inhomogeneous plasma sheath. The results show the noticeable effects of dusty plasma parameters on EM waves.

Jupiter plasma wave observations: an initial voyager 1 overview.

PubMed

Scarf, F L; Gurnett, D A; Kurth, W S

1979-06-01

The Voyager I plasma wave instrument detected low-frequency radio emissions, ion acoustic waves, and electron plasma oscillations for a period of months before encountering Jupiter's bow shock. In the outer magnetosphere, measurements of trapped radio waves were used to derive an electron density profile. Near and within the Io plasma torus the instrument detected high-frequency electrostatic waves, strong whistler mode turbulence, and discrete whistlers, apparently associated with lightning. Some strong emissions in the tail region and some impulsive signals have not yet been positively identified.

Experiments on Alfv'en waves in high beta plasmas

NASA Astrophysics Data System (ADS)

Gekelman, Walter; Pribyl, Patrick; Cooper, Chris; Vincena, Stephen

2008-11-01

The propagation of Alfv'en waves in high beta plasmas is of great interest in solar wind studies as well as in astrophysical plasmas. Alfv'en wave propagation in a high beta plasma is studied on the axis of a toroidal device at UCLA. The vacuum vessel is 30 meters in circumference, 2 meters wide and 3 meters tall. The plasma has a cross sectional area of 20 cm^2 and can be as long as 120 m which is hundreds of parallel Alfv'en wavelengths. The waves are launched using two orthogonal 5-turn , 5.7 cm diameter loops. The AC currents (10 kHz < f < 250 kHz) to the loops are as high as 2 kA p-p, producing fields of 1 kG on the axis of the antenna. The antenna coils are independently driven such that waves with arbitrary polarization can be launched. Movable three axis magnetic pickup loops detect the wave and are used to construct field maps in the machine. Wave propagation results as a function of plasma beta and input wave energy will be presented.

Survey of EBW Mode-Conversion Characteristics for Various Boundary Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, H.; Maekawa, T.; Igami, H.

2005-09-26

A survey of linear mode-conversion characteristics between external transverse electromagnetic (TEM) waves and electron Bernstein waves (EBW) for various plasma and wave parameters has been presented. It is shown that if the wave propagation angle and polarization are adjusted appropriately for each individual case of the plasma parameters, efficient mode conversion occur for wide range of plasma parameters where the conventional 'XB' and 'OXB' scheme cannot cover. It is confirmed that the plasma parameters just at the upper hybrid resonance (UHR) layer strongly affect the mode conversion process and the influence of the plasma profiles distant from the UHR layermore » is not so much. The results of this survey is useful enough to examine wave injection/detection condition for efficient ECH/ECCD or measurement of emissive TEM waves for each individual experimental condition of overdense plasmas.« less

Many-body problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parry, W.E.

1973-01-01

An introduction is given to techniques used in the many-body problem, and a reference book is given for those techniques. Sevcral different formulations of the techniques, and their interrelations, are discussed, to prepare the reader for the published literature. Examples are taken mostly from the physics of solids, fluids and plasmas. Second quantization, perturbation theory, Green functions and correlation functions, examples in the use of diagrammatic perturbation theory, the equation of motion method, magnetism (the drone-fermion representation), linear response and transport processes, niany- body systems at zero temperature, the variational principle and pair-wave approximation. (UK)

VLF and HF Plasma Waves Associated with Spread-F Plasma Depletions Observed on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, Robert; Freudenreich, H.; Schuck, P.; Klenzing, J.

2011-01-01

The C/NOFS spacecraft frequently encounters structured plasma depletions associated with equatorial spread-F along its trajectory that varies between 401 km perigee and 867 km apogee in the low latitude ionosphere. We report two classes of plasma waves detected with the Vector Electric Field Investigation (VEFI) that appear when the plasma frequency is less than the electron gyro frequency, as is common in spread-F depletions where the plasma number density typically decreases below 10(exp 4)/cu cm. In these conditions, both broadband VLF waves with a clear cutoff at the lower hybrid frequency and broadband HF waves with a clear cutoff at the plasma frequency are observed. We interpret these waves as "hiss-type" emissions possibly associated with the flow of suprathermal electrons within the inter-hemispherical magnetic flux tubes. We also report evidence of enhanced wave "transients" sometimes embedded in the broader band emissions that are associated with lightning sferics detected within the depleted plasma regions that appear in both the VLF and HF data. Theoretical implications of these observations are discussed.

Consequences of the Ion Cyclotron Instability in the Inner Magnetospheric Plasma

NASA Technical Reports Server (NTRS)

Khazanov, George V.

2011-01-01

The inner magnetospheric plasma is a very unique composition of different plasma particles and waves. Among these plasma particles and waves are Ring Current (RC) particles and Electromagnetic Ion Cyclotron (EMIC) waves. The RC is the source of free energy for the EMIC wave excitation provided by a temperature anisotropy of RC ions, which develops naturally during inward E x B convection from the plasma sheet. The cold plasmasphere, which is under the strong influence of the magnetospheric electric field, strongly mediates the RC-EMIC waves-coupling process, and ultimately becomes part of the particle and energy interplay, generated by the ion cyclotron instability of the inner magnetosphere. On the other hand, there is a strong influence of the RC on the inner magnetospheric electric and magnetic field configurations and these configurations, in turn, are important to RC dynamics. Therefore, one of the biggest needs for inner magnetospheric plasma physics research is the continued progression toward a coupled, interconnected system, with the inclusion of nonlinear feedback mechanisms between the plasma populations, the electric and magnetic fields, and plasma waves.

Electron Density Measurement on JUICE Mission by Mutual Impedance Technique: MIME Instrument as a Part of RPWI Consortium

NASA Astrophysics Data System (ADS)

Rauch, J. L.; Henri, P.; Wahlund, J. E.; Le Duff, O.; Sene, O.; Colin, F.; Lagoutte, D.; Gilet, N.; Ahlen, L.; Bergman, J.; Gill, R.; Puccio, W.

2017-09-01

Mutual Impedance MEasurements (MIME) instrument is a part of the Radio Wave Plasma Investigation (RPWI) consortium which has been selected by European Space Agency (ESA) on the nest planetary mission JJUpiter ICy moons Exploer (JUICE) for a launch in 2022. The goals are to explore Jupiter and its potentially habitable icy moons and to study its plasma environment. Impedance probes, which are well known in geophysical prospection, in particular for ground permittivity investigations, have been successfully transposed to space plasmas diagnostic. Transmitting and receiving electrodes are used for measuring on open circuit the dynamic impedance of the system at several fixed frequencies over a range that includes characteristic frequencies of the ambient plasma. The measurements are then interpreted using a suitable theory and the values of plasma parameters, such as the electron density and possibly the temperature of the plasma can be deduced. To show how powerful this technique is, results obtained in the Earth's plasmasphere by the mutual impedance probe onboard ROSETTA are presented as example. MIME instrument proposal is then described and its ability to make valuable measurements in the Jupiter space environment and in particular around Europe, Callisto and Ganymede is investigated..

Effect of anisotropic dust pressure and superthermal electrons on propagation and stability of dust acoustic solitary waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bashir, M. F., E-mail: frazbashir@yahoo.com; Behery, E. E., E-mail: eebehery@gmail.com; Department of Physics, Faculty of Science, Damietta University, P.O. 34517, New Damietta

2015-06-15

Employing the reductive perturbation technique, Zakharov–Kuznetzov (ZK) equation is derived for dust acoustic (DA) solitary waves in a magnetized plasma which consists the effects of dust anisotropic pressure, arbitrary charged dust particles, Boltzmann distributed ions, and Kappa distributed superthermal electrons. The ZK solitary wave solution is obtained. Using the small-k expansion method, the stability analysis for DA solitary waves is also discussed. The effects of the dust pressure anisotropy and the electron superthermality on the basic characteristics of DA waves as well as on the three-dimensional instability criterion are highlighted. It is found that the DA solitary wave is rarefactivemore » (compressive) for negative (positive) dust. In addition, the growth rate of instability increases rapidly as the superthermal spectral index of electrons increases with either positive or negative dust grains. A brief discussion for possible applications is included.« less

Demonstration of sawtooth period control with EC waves in KSTAR plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeong, J. H.; Bae, Y. S.; Joung, M.

2015-03-12

The sawtooth period control in tokamak is important issue in recent years because the sawtooth crash can trigger TM/NTM instabilities and drive plasmas unstable. The control of sawtooth period by the modification of local current profile near the q=1 surface using ECCD has been demonstrated in a number of tokamaks [1, 2] including KSTAR. As a result, developing techniques to control the sawtooth period as a way of controlling the onset of NTM has been an important area of research in recent years [3]. In 2012 KSTAR plasma campaign, the sawtooth period control is carried out by the different depositionmore » position of EC waves across the q=1 surface. The sawtooth period is shortened by on-axis co-ECCD (destabilization), and the stabilization of the sawtooth is also observed by off-axis co-ECCD at outside q=1 surface. In 2013 KSTAR plasma campaign, the sawtooth locking experiment with periodic forcing of 170 GHz EC wave is carried out to control the sawtooth period. The optimal target position which lengthens the sawtooth period is investigated by performing a scan of EC beam deposition position nearby q=1 surface at the toroidal magnetic field of 2.9 T and plasma current of 0.7 MA. The sawtooth locking by the modulated EC beam is successfully demonstrated as in [3-5] with the scan of modulation-frequency and duty-ratio at the low beta (β N~0.5) plasma. In this paper, the sawteeth behavior by the location of EC beam and the preliminary result of the sawtooth locking experiments in KSTAR will be presented.« less

Design of a novel high efficiency antenna for helicon plasma sources

NASA Astrophysics Data System (ADS)

Fazelpour, S.; Chakhmachi, A.; Iraji, D.

2018-06-01

A new configuration for an antenna, which increases the absorption power and plasma density, is proposed for helicon plasma sources. The influence of the electromagnetic wave pattern symmetry on the plasma density and absorption power in a helicon plasma source with a common antenna (Nagoya) is analysed by using the standard COMSOL Multiphysics 5.3 software. In contrast to the theoretical model prediction, the electromagnetic wave does not represent a symmetric pattern for the common Nagoya antenna. In this work, a new configuration for an antenna is proposed which refines the asymmetries of the wave pattern in helicon plasma sources. The plasma parameters such as plasma density and absorption rate for a common Nagoya antenna and our proposed antenna under the same conditions are studied using simulations. In addition, the plasma density of seven operational helicon plasma source devices, having a common Nagoya antenna, is compared with the simulation results of our proposed antenna and the common Nagoya antenna. The simulation results show that the density of the plasma, which is produced by using our proposed antenna, is approximately twice in comparison to the plasma density produced by using the common Nagoya antenna. In fact, the simulation results indicate that the electric and magnetic fields symmetry of the helicon wave plays a vital role in increasing wave-particle coupling. As a result, wave-particle energy exchange and the plasma density of helicon plasma sources will be increased.

Study and optimization of lower hybrid wave coupling in advanced scenario plasmas in JET

NASA Astrophysics Data System (ADS)

Pericoli Ridolfini, V.; Ekedahl, A.; Erents, S. K.; Mailloux, J.; Podda, S.; Sarazin, Y.; Tuccillo, A. A.; Workprogramme contributors, EFDA-JET

2004-02-01

Active current drive with lower hybrid (LH) waves in the advanced scenario plasmas at JET-EFDA was successful after a systematic study of the coupling problems that derive from the H-mode features of the edge plasma, namely very low density and ELM activity. The LH coupling has been improved compared to the past, by making the edge plasma in front of the LH launcher denser and more uniform. Injecting deuterated methane (CD4) from a nearby gas pipe increases the density in front of the LH launcher at least by a factor of 1.5, above the cut-off value for the LH frequency. A better matching of the plasma shape to that of the LH antenna makes the plasma ahead of the LH launcher more regular along the poloidal angle. These two techniques together have permitted a balanced supply of the three LH grills, with an average reflection below 4%, as in the previous L-mode operation. CD4 does not affect the performances nor does it contaminate the main plasma up to the maximum flow rate so far used, \\Phi_{CD_4}>10^{22}el\\,s^{-1} and now it is routinely applied in JET (up to 4 MW have been injected for longer than 8 s) with very encouraging results for LHCD. Even though CD4 is not suitable for ITER for tritium retention, the possibility of controlling locally and safely the scrape-off plasma density has been demonstrated.

Simulations of Atmospheric Neutral Wave Coupling to the Ionosphere

NASA Astrophysics Data System (ADS)

Siefring, C. L.; Bernhardt, P. A.

2005-12-01

The densities in the E- and F-layer plasmas are much less than the density of background neutral atmosphere. Atmospheric neutral waves are primary sources of plasma density fluctuations and are the sources for triggering plasma instabilities. The neutral atmosphere supports acoustic waves, acoustic gravity waves, and Kelvin Helmholtz waves from wind shears. These waves help determine the structure of the ionosphere by changes in neutral density that affect ion-electron recombination and by neutral velocities that couple to the plasma via ion-neutral collisions. Neutral acoustic disturbances can arise from thunderstorms, chemical factory explosions and intentional high-explosive tests. Based on conservation of energy, acoustic waves grow in amplitude as they propagate upwards to lower atmospheric densities. Shock waves can form in an acoustic pulse that is eventually damped by viscosity. Ionospheric effects from acoustic waves include transient perturbations of E- and F-Regions and triggering of E-Region instabilities. Acoustic-gravity waves affect the ionosphere over large distances. Gravity wave sources include thunderstorms, auroral region disturbances, Space Shuttle launches and possibly solar eclipses. Low frequency acoustic-gravity waves propagate to yield traveling ionospheric disturbances (TID's), triggering of Equatorial bubbles, and possible periodic structuring of the E-Region. Gravity wave triggering of equatorial bubbles is studied numerically by solving the equations for plasma continuity and ion velocity along with Ohms law to provide an equation for the induced electric potential. Slow moving gravity waves provide density depressions on bottom of ionosphere and a gravitational Rayleigh-Taylor instability is initiated. Radar scatter detects field aligned irregularities in the resulting plasma bubble. Neutral Kelvin-Helmholtz waves are produced by strong mesospheric wind shears that are also coincident with the formation of intense E-layers. An atmospheric model for periodic structures with Kelvin-Helmholtz (KH) wavelengths is used to show the development of quasi-periodic structures in the E-layer. For the model, a background atmosphere near 100 km altitude with a scale height of 12.2 km is subjected to a wind shear profile varying by 100 m/s over a distance of 1.7 km. This neutral speed shear drives the KH instability with a growth time of about 100 seconds. The neutral KH wave is a source of plasma turbulence. The E-layer responds to the KH-Wave structure in the neutral atmosphere as an electrodynamic tracer. The plasma flow leads to small scale plasma field aligned irregularities from a gradient drift, plasma interchange instability (GDI) or a Farley-Buneman, two-stream instability (FBI). These irregularities are detected by radar scatter as quasi-periodic structures. All of these plasma phenomena would not occur without the initiation by neutral atmospheric waves.

Research on the FDTD method of scattering effects of obliquely incident electromagnetic waves in time-varying plasma sheath on collision and plasma frequencies

NASA Astrophysics Data System (ADS)

Chen, Wei; Guo, Li-xin; Li, Jiang-ting

2017-04-01

This study analyzes the scattering characteristics of obliquely incident electromagnetic (EM) waves in a time-varying plasma sheath. The finite-difference time-domain algorithm is applied. According to the empirical formula of the collision frequency in a plasma sheath, the plasma frequency, temperature, and pressure are assumed to vary with time in the form of exponential rise. Some scattering problems of EM waves are discussed by calculating the radar cross section (RCS) of the time-varying plasma. The laws of the RCS varying with time are summarized at the L and S wave bands.

Development of FullWave : Hot Plasma RF Simulation Tool

NASA Astrophysics Data System (ADS)

Svidzinski, Vladimir; Kim, Jin-Soo; Spencer, J. Andrew; Zhao, Liangji; Galkin, Sergei

2017-10-01

Full wave simulation tool, modeling RF fields in hot inhomogeneous magnetized plasma, is being developed. The wave equations with linearized hot plasma dielectric response are solved in configuration space on adaptive cloud of computational points. The nonlocal hot plasma dielectric response is formulated in configuration space without limiting approximations by calculating the plasma conductivity kernel based on the solution of the linearized Vlasov equation in inhomogeneous magnetic field. This approach allows for better resolution of plasma resonances, antenna structures and complex boundaries. The formulation of FullWave and preliminary results will be presented: construction of the finite differences for approximation of derivatives on adaptive cloud of computational points; model and results of nonlocal conductivity kernel calculation in tokamak geometry; results of 2-D full wave simulations in the cold plasma model in tokamak geometry using the formulated approach; results of self-consistent calculations of hot plasma dielectric response and RF fields in 1-D mirror magnetic field; preliminary results of self-consistent simulations of 2-D RF fields in tokamak using the calculated hot plasma conductivity kernel; development of iterative solver for wave equations. Work is supported by the U.S. DOE SBIR program.

Multidimensional nonlinear ion-acoustic waves in a plasma in view of relativistic effects

NASA Astrophysics Data System (ADS)

Belashov, V. Yu.

2017-05-01

The structure and dynamics of ion-acoustic waves in an unmagnetized plasma, including the case of weakly relativistic collisional plasma (when it is necessary to take into account the high energy particle flows which are observed in the magnetospheric plasma), are studied analytically and numerically on the basis of a model of the Kadomtsev-Petviashvili (KP) equation. It is shown that, if the velocity of plasma particles approaches the speed of light, the relativistic effects start to strongly influence on the wave characteristics, such as its phase velocity, amplitude, and characteristic wavelength, with the propagation of the twodimensional solitary ion-acoustic wave. The results can be used in the study of nonlinear wave processes in the magnetosphere and in laser and astrophysical plasma.

Voyager 2 plasma wave observations at saturn.

PubMed

Scarf, F L; Gurnett, D A; Kurth, W S; Poynter, R L

1982-01-29

The first inbound Voyager 2 crossing of Saturn's bow shock [at 31.7 Saturn radii (RS), near local noon] and the last outbound crossing (at 87.4 RS, near local dawn) had similar plasma wave signatures. However, many other aspects of the plasma wave measurements differed considerably during the inbound and outbound passes, suggesting the presence of effects associated with significant north-south or noon-dawn asymmetries, or temporal variations. Within Saturn's magnetosphere, the plasma wave instrument detected electron plasma oscillations, upper hybrid resonance emissions, half-gyrofrequency harmonics, hiss and chorus, narrowband electromagnetic emissions and broadband Saturn radio noise, and noise bursts with characteristics of static. At the ring plane crossing, the plasma wave instrument also detected a large number of intense impulses that we interpret in terms of ring particle impacts on Voyager 2.

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Labany, S. K., E-mail: skellabany@hotmail.com; Zedan, N. A., E-mail: nesreenplasma@yahoo.com; El-Taibany, W. F., E-mail: eltaibany@hotmail.com, E-mail: eltaibany@du.edu.eg

The nonplanar amplitude modulation of dust acoustic (DA) envelope solitary waves in a strongly coupled dusty plasma (SCDP) has been investigated. By using a reductive perturbation technique, a modified nonlinear Schrödinger equation (NLSE) including the effects of geometry, polarization, and ion superthermality is derived. The modulational instability (MI) of the nonlinear DA wave envelopes is investigated in both planar and nonplanar geometries. There are two stable regions for the DA wave propagation strongly affected by polarization and ion superthermality. Moreover, it is found that the nonlinear DA waves in spherical geometry are the more structurally stable. The larger growth ratemore » of the nonlinear DA MI is observed in the cylindrical geometry. The salient characteristics of the MI in the nonplanar geometries cannot be found in the planar one. The DA wave propagation and the NLSE solutions are investigated both analytically and numerically.« less

International Conference on Infrared and Millimeter Waves, 13th, Honolulu, HI, Dec. 5-9, 1988, Conference Digest

NASA Astrophysics Data System (ADS)

Temkin, Richard J.

Recent advances in IR and mm-wave (MMW) physics, astrophysics, devices, and applications are examined in reviews and reports. Sections are devoted to MMW sources, MMW modulation of light, MMW antennas, FELs, MMW optical technology, astronomy, MMW systems, microwave-optical interactions, MMW waveguides, MMW detectors and mixers, plasma diagnostics, and atmospheric physics. Also considered are gyrotrons, guided propagation, high-Tc superconductors, sub-MMW detectors and related devices, ICs, near-MMW measurements and techniques, lasers, material characterization, semiconductors, and atmospheric propagation.

International Conference on Infrared and Millimeter Waves, 15th, Orlando, FL, Dec. 10-14, 1990, Conference Digest

NASA Astrophysics Data System (ADS)

Temkin, Richard J.

Recent advances in IR and mm-wave (MMW) technology and applications are discussed in reviews and reports. Sections are devoted to MMW sources, high-Tc superconductors, atmospheric physics, FEL technology, astronomical instrumentation, MMW systems, measurement techniques, MMW guides, and MMW detectors and mixers. Also discussed are material properties, gyrotrons, guided propagation, semiconductors, submm detectors and devices, material characterization methods, ICs, MMW guides and plasma diagnostics, lasers, and MMW antennas. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided.

Waves generated in the plasma plume of helicon magnetic nozzle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Nagendra; Rao, Sathyanarayan; Ranganath, Praveen

2013-03-15

Experimental measurements have shown that the plasma plume created in a helicon plasma device contains a conical structure in the plasma density and a U-shaped double layer (US-DL) tightly confined near the throat where plasma begins to expand from the source. Recently reported two-dimensional particle-in-cell simulations verified these density and US-DL features of the plasma plume. Simulations also showed that the plasma in the plume develops non-thermal feature consisting of radial ion beams with large densities near the conical surface of the density structure. The plasma waves that are generated by the radial ion beams affecting the structure of themore » plasma plume are studied here. We find that most intense waves persist in the high-density regions of the conical density structure, where the transversely accelerated ions in the radial electric fields in the plume are reflected setting up counter-streaming. The waves generated are primarily ion Bernstein modes. The nonlinear evolution of the waves leads to magnetic field-aligned striations in the fields and the plasma near the conical surface of the density structure.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vincena, Stephen

The aim of the original proposal was a basic plasma study to experimentally investigate the fundamental physics of how dense, fast-flowing, and field-aligned jets of plasma couple energy and momentum to a much larger, ambient, magnetized plasma. Coupling channels that were explored included bulk plasma heating and flow generation; shock wave production; and wave radiation, particularly in the form of shear and compressional Alfvén waves. The wave radiation, particularly to shear Alfvén waves was successfully modeled using the 3D Particle-In-Cell code, OSIRIS. Experimentally, these jets were produced via pulsed Nd:YAG laser ablation of solid carbon (graphite) rods, which were immersedmore » in the main plasma column of the Large Plasma Device (LaPD) at UCLA’s Basic Plasma Science Facility (BaPSF.) The axial expansion of the laser-produced plasma (LPP) was supersonic and with parallel expansion speeds approximately equal to the Alfvén speed. The project was renewed and refocused efforts to then utilize the laser-produced plasmas as a tool for the disruption and reconnection of current sheets in magnetized plasmas« less

Three-wave scattering in magnetized plasmas: From cold fluid to quantized Lagrangian

DOE PAGES

Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

2017-08-14

Large amplitude waves in magnetized plasmas, generated either by external pumps or internal instabilities, can scatter via three-wave interactions. While three-wave scattering is well known in collimated geometry, what happens when waves propagate at angles with one another in magnetized plasmas remains largely unknown, mainly due to the analytical difficulty of this problem. In this study, we overcome this analytical difficulty and find a convenient formula for three-wave coupling coefficient in cold, uniform, magnetized, and collisionless plasmas in the most general geometry. This is achieved by systematically solving the fluid-Maxwell model to second order using a multiscale perturbative expansion. Themore » general formula for the coupling coefficient becomes transparent when we reformulate it as the scattering matrix element of a quantized Lagrangian. Using the quantized Lagrangian, it is possible to bypass the perturbative solution and directly obtain the nonlinear coupling coefficient from the linear response of the plasma. To illustrate how to evaluate the cold coupling coefficient, we give a set of examples where the participating waves are either quasitransverse or quasilongitudinal. In these examples, we determine the angular dependence of three-wave scattering, and demonstrate that backscattering is not necessarily the strongest scattering channel in magnetized plasmas, in contrast to what happens in unmagnetized plasmas. Finally, our approach gives a more complete picture, beyond the simple collimated geometry, of how injected waves can decay in magnetic confinement devices, as well as how lasers can be scattered in magnetized plasma targets.« less

Three-wave scattering in magnetized plasmas: From cold fluid to quantized Lagrangian.

PubMed

Shi, Yuan; Qin, Hong; Fisch, Nathaniel J

2017-08-01

Large amplitude waves in magnetized plasmas, generated either by external pumps or internal instabilities, can scatter via three-wave interactions. While three-wave scattering is well known in collimated geometry, what happens when waves propagate at angles with one another in magnetized plasmas remains largely unknown, mainly due to the analytical difficulty of this problem. In this paper, we overcome this analytical difficulty and find a convenient formula for three-wave coupling coefficient in cold, uniform, magnetized, and collisionless plasmas in the most general geometry. This is achieved by systematically solving the fluid-Maxwell model to second order using a multiscale perturbative expansion. The general formula for the coupling coefficient becomes transparent when we reformulate it as the scattering matrix element of a quantized Lagrangian. Using the quantized Lagrangian, it is possible to bypass the perturbative solution and directly obtain the nonlinear coupling coefficient from the linear response of the plasma. To illustrate how to evaluate the cold coupling coefficient, we give a set of examples where the participating waves are either quasitransverse or quasilongitudinal. In these examples, we determine the angular dependence of three-wave scattering, and demonstrate that backscattering is not necessarily the strongest scattering channel in magnetized plasmas, in contrast to what happens in unmagnetized plasmas. Our approach gives a more complete picture, beyond the simple collimated geometry, of how injected waves can decay in magnetic confinement devices, as well as how lasers can be scattered in magnetized plasma targets.

Three-wave scattering in magnetized plasmas: From cold fluid to quantized Lagrangian

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

Large amplitude waves in magnetized plasmas, generated either by external pumps or internal instabilities, can scatter via three-wave interactions. While three-wave scattering is well known in collimated geometry, what happens when waves propagate at angles with one another in magnetized plasmas remains largely unknown, mainly due to the analytical difficulty of this problem. In this study, we overcome this analytical difficulty and find a convenient formula for three-wave coupling coefficient in cold, uniform, magnetized, and collisionless plasmas in the most general geometry. This is achieved by systematically solving the fluid-Maxwell model to second order using a multiscale perturbative expansion. Themore » general formula for the coupling coefficient becomes transparent when we reformulate it as the scattering matrix element of a quantized Lagrangian. Using the quantized Lagrangian, it is possible to bypass the perturbative solution and directly obtain the nonlinear coupling coefficient from the linear response of the plasma. To illustrate how to evaluate the cold coupling coefficient, we give a set of examples where the participating waves are either quasitransverse or quasilongitudinal. In these examples, we determine the angular dependence of three-wave scattering, and demonstrate that backscattering is not necessarily the strongest scattering channel in magnetized plasmas, in contrast to what happens in unmagnetized plasmas. Finally, our approach gives a more complete picture, beyond the simple collimated geometry, of how injected waves can decay in magnetic confinement devices, as well as how lasers can be scattered in magnetized plasma targets.« less

Electrostatic wave heating and possible formation of self-generated high electric fields in a magnetized plasma

NASA Astrophysics Data System (ADS)

Mascali, D.; Celona, L.; Gammino, S.; Miracoli, R.; Castro, G.; Gambino, N.; Ciavola, G.

2011-10-01

A plasma reactor operates at the Laboratori Nazionali del Sud of INFN, Catania, and it has been used as a test-bench for the investigation of innovative mechanisms of plasma ignition based on electrostatic waves (ES-W), obtained via the inner plasma EM-to-ES wave conversion. Evidences of Bernstein wave (BW) generation will be shown. The Langmuir probe measurements have revealed a strong increase of the ion saturation current, where the BW are generated or absorbed, this being a signature of possible high energy ion flows. The results are interpreted through the Bernstein wave heating theory, which predicts the formation of high speed rotating layers of the plasma (a dense plasma ring is in fact observed). High intensity inner plasma self-generated electric fields (on the order of several tens of kV/cm) come out by our calculations.

Macroscopic Lagrangian description of warm plasmas. II Nonlinear wave interactions

NASA Technical Reports Server (NTRS)

Kim, H.; Crawford, F. W.

1983-01-01

A macroscopic Lagrangian is simplified to the adiabatic limit and expanded about equilibrium, to third order in perturbation, for three illustrative cases: one-dimensional compression parallel to the static magnetic field, two-dimensional compression perpendicular to the static magnetic field, and three-dimensional compression. As examples of the averaged-Lagrangian method applied to nonlinear wave interactions, coupling coefficients are derived for interactions between two electron plasma waves and an ion acoustic wave, and between an ordinary wave, an electron plasma wave, and an ion acoustic wave.

Historical overview of HF ionospheric modification research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, W.E.; Duncan, L.M.

1990-10-01

Radio waves have inadvertently modified the Earth's ionosphere since the Luxembourg observations of Tellegen in 1933 and perhaps since Marconi in 1901. The history of ionospheric modification by radio waves is reviewed, beginning with Marconi, describing the Luxembourg effect and its explanations, and its early use to deduce the properties of the lower ionosphere in the 1930s. The measurements became more sophisticated in the 1950s, leading to the call for high-power high-frequency modification experiments in the upper ionosphere. Beginning in 1970, radio facilities became available of sufficient powers to induce changes in the ionospheric plasma detectable by a wide arraymore » of diagnostic instruments and techniques. A summary of these effects is presented based upon work up to 1990. These studies were originally motivated as a means of better understanding the natural ionosphere using a weak perturbational approach. However, a rich spectrum of nonlinear wave-plasma interactions was quickly discovered and ionospheric modification research became strongly motivated by issues in basic plasma physics. The ionosphere and near-Earth space are now exploited as an exceptional plasma laboratory-without-walls for the study of fundamental plasma processes requiring large spatial or temporal scales. Here we present a brief overview of these processes and phenomena, illustrated using results obtained from the Arecibo ionospheric modification facilities. The lessons learned and phenomena explored thus far offer many opportunities for controlling the ionospheric environment critical to many civilian and military telecommunications systems, both to disrupt systems normally operational and to create new propagation paths otherwise unavailable.« less

Upstream waves and particles /Tutorial Lecture/. [from shocks in interplanetary space

NASA Technical Reports Server (NTRS)

Russell, C. T.; Hoppe, M. M.

1983-01-01

The plasma waves, MHD waves, energetic electrons and ions associated with the proximity of the region upstream from terrestrial, planetary and interplanetary shocks are discussed in view of observations and current theories concerning their origin. These waves cannot be separated from the study of shock structure. Since the shocks are supersonic, they continually overtake any ULF waves created in the plasma in front of the shock. The upstream particles and waves are also of intrinsic interest because they provide a plasma laboratory for the study of wave-particle interactions in a plasma which, at least at the earth, is accessible to sophisticated probing. Insight may be gained into interstellar medium cosmic ray acceleration through the study of these phenomena.

Study of Linear and Nonlinear Waves in Plasma Crystals Using the Box_Tree Code

NASA Astrophysics Data System (ADS)

Qiao, K.; Hyde, T.; Barge, L.

Dusty plasma systems play an important role in both astrophysical and planetary environments (protostellar clouds, planetary ring systems and magnetospheres, cometary environments) and laboratory settings (plasma processing or nanofabrication). Recent research has focussed on defining (both theoretically and experimentally) the different types of wave mode propagations, which are possible within plasma crystals. This is an important topic since several of the fundamental quantities for characterizing such crystals can be obtained directly from an analysis of the wave propagation/dispersion. This paper will discuss a num rical model fore 2D-monolayer plasma crystals, which was established using a modified box tree code. Different wave modes were examined by adding a time dependent potential to the code designed to simulate a laser radiation perturbation as has been applied in many experiments. Both linear waves (for example, longitudinal and transverse dust lattice waves) and nonlinear waves (solitary waves) are examined. The output data will also be compared with the results of corresponding experiments and discussed.

Twisted electron-acoustic waves in plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aman-ur-Rehman, E-mail: amansadiq@gmail.com; Department of Physics and Applied Mathematics; Ali, S.

2016-08-15

In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number q{sub eff} accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping ratemore » of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.« less

Wave-particle interactions in rotating mirrorsa)

NASA Astrophysics Data System (ADS)

Fetterman, Abraham J.; Fisch, Nathaniel J.

2011-05-01

Wave-particle interactions in E ×B rotating plasmas feature an unusual effect: particles are diffused by waves in both potential energy and kinetic energy. This wave-particle interaction generalizes the alpha channeling effect, in which radio frequency waves are used to remove alpha particles collisionlessly at low energy. In rotating plasmas, the alpha particles may be removed at low energy through the loss cone, and the energy lost may be transferred to the radial electric field. This eliminates the need for electrodes in the mirror throat, which have presented serious technical issues in past rotating plasma devices. A particularly simple way to achieve this effect is to use a high azimuthal mode number perturbation on the magnetic field. Rotation can also be sustained by waves in plasmas without a kinetic energy source. This type of wave has been considered for plasma centrifuges used for isotope separation. Energy may also be transferred from the electric field to particles or waves, which may be useful for ion heating and energy generation.

Magnetosonic waves interactions in a spin-1/2 degenerate quantum plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Sheng-Chang, E-mail: lsc1128lsc@126.com; Han, Jiu-Ning

2014-03-15

We investigate the magnetosonic waves and their interactions in a spin-1/2 degenerate quantum plasma. With the help of the extended Poincaré-Lighthill-Kuo perturbation method, we derive two Korteweg-de Vries-Burgers equations to describe the magnetosonic waves. The parameter region where exists magnetosonic waves and the phase diagram of the compressive and rarefactive solitary waves with different plasma parameters are shown. We further explore the effects of quantum diffraction, quantum statistics, and electron spin magnetization on the head-on collisions of magnetosonic solitary waves. We obtain the collision-induced phase shifts (trajectory changes) analytically. Both for the compressive and rarefactive solitary waves, it is foundmore » that the collisions only lead to negative phase shifts. Our present study should be useful to understand the collective phenomena related to the magnetosonic wave collisions in degenerate plasmas like those in the outer shell of massive white dwarfs as well as to the potential applications of plasmas.« less

Modulational instability of an electron plasma wave in a dusty plasma

NASA Astrophysics Data System (ADS)

Amin, M. R.; Ferdous, T.; Salimullah, M.

1997-03-01

The modulational instability of an electron plasma wave in a homogeneous, unmagnetized, hot, and collisionless dusty plasma has been investigated analytically. The Vlasov equation has been solved perturbatively to find the nonlinear response of the plasma particles with random static distribution of massive and charged dust grains having certain correlation. It is noticed that the growth rate of the modulational instability of the electron plasma wave through a new ultra-low-frequency dust mode is more efficient than that through the usual ion-acoustic mode in the dusty plasma.

Exchange interaction effects on waves in magnetized quantum plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trukhanova, Mariya Iv., E-mail: mar-tiv@yandex.ru; Andreev, Pavel A., E-mail: andreevpa@physics.msu.ru

2015-02-15

We have applied the many-particle quantum hydrodynamics that includes the Coulomb exchange interaction to magnetized quantum plasmas. We considered a number of wave phenomena that are affected by the Coulomb exchange interaction. Since the Coulomb exchange interaction affects the longitudinal and transverse-longitudinal waves, we focused our attention on the Langmuir waves, the Trivelpiece-Gould waves, the ion-acoustic waves in non-isothermal magnetized plasmas, the dispersion of the longitudinal low-frequency ion-acoustic waves, and low-frequency electromagnetic waves at T{sub e} ≫ T{sub i}. We have studied the dispersion of these waves and present the numeric simulation of their dispersion properties.

Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

NASA Astrophysics Data System (ADS)

Bowen, LI; Zhibin, WANG; Qiuyue, NIE; Xiaogang, WANG; Fanrong, KONG; Zhenyu, WANG

2018-01-01

Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves, particularly in the sub-wavelength regime. To investigate the collisional effect in such plasmas, we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave. The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity. Results show that the collisions between the electrons and the neutral particles, as well as the incident angle and the plasma thickness, can disturb the transmission and reduce reflection significantly.

Millimeter-wave imaging of magnetic fusion plasmas: technology innovations advancing physics understanding

NASA Astrophysics Data System (ADS)

Wang, Y.; Tobias, B.; Chang, Y.-T.; Yu, J.-H.; Li, M.; Hu, F.; Chen, M.; Mamidanna, M.; Phan, T.; Pham, A.-V.; Gu, J.; Liu, X.; Zhu, Y.; Domier, C. W.; Shi, L.; Valeo, E.; Kramer, G. J.; Kuwahara, D.; Nagayama, Y.; Mase, A.; Luhmann, N. C., Jr.

2017-07-01

Electron cyclotron emission (ECE) imaging is a passive radiometric technique that measures electron temperature fluctuations; and microwave imaging reflectometry (MIR) is an active radar imaging technique that measures electron density fluctuations. Microwave imaging diagnostic instruments employing these techniques have made important contributions to fusion science and have been adopted at major fusion facilities worldwide including DIII-D, EAST, ASDEX Upgrade, HL-2A, KSTAR, LHD, and J-TEXT. In this paper, we describe the development status of three major technological advancements: custom mm-wave integrated circuits (ICs), digital beamforming (DBF), and synthetic diagnostic modeling (SDM). These have the potential to greatly advance microwave fusion plasma imaging, enabling compact and low-noise transceiver systems with real-time, fast tracking ability to address critical fusion physics issues, including ELM suppression and disruptions in the ITER baseline scenario, naturally ELM-free states such as QH-mode, and energetic particle confinement (i.e. Alfvén eigenmode stability) in high-performance regimes that include steady-state and advanced tokamak scenarios. Furthermore, these systems are fully compatible with today’s most challenging non-inductive heating and current drive systems and capable of operating in harsh environments, making them the ideal approach for diagnosing long-pulse and steady-state tokamaks.

Millimeter-wave imaging of magnetic fusion plasmas: technology innovations advancing physics understanding

DOE PAGES

Wang, Y.; Tobias, B.; Chang, Y. -T.; ...

2017-03-14

Electron cyclotron emission (ECE) imaging is a passive radiometric technique that measures electron temperature fluctuations; and microwave imaging reflectometry (MIR) is an active radar imaging technique that measures electron density fluctuations. The microwave imaging diagnostic instruments employing these techniques have made important contributions to fusion science and have been adopted at major fusion facilities worldwide including DIII-D, EAST, ASDEX Upgrade, HL-2A, KSTAR, LHD, and J-TEXT. In this paper, we describe the development status of three major technological advancements: custom mm-wave integrated circuits (ICs), digital beamforming (DBF), and synthetic diagnostic modeling (SDM). These also have the potential to greatly advance microwavemore » fusion plasma imaging, enabling compact and low-noise transceiver systems with real-time, fast tracking ability to address critical fusion physics issues, including ELM suppression and disruptions in the ITER baseline scenario, naturally ELM-free states such as QH-mode, and energetic particle confinement (i.e. Alfven eigenmode stability) in high-performance regimes that include steady-state and advanced tokamak scenarios. Furthermore, these systems are fully compatible with today's most challenging non-inductive heating and current drive systems and capable of operating in harsh environments, making them the ideal approach for diagnosing long-pulse and steady-state tokamaks.« less

Electron density inversed by plasma lines induced by suprathermal electron in the ionospheric modification experiment

NASA Astrophysics Data System (ADS)

Wang, Xiang; Zhou, Chen

2018-05-01

Incoherent scatter radar (ISR) is the most powerful ground-based measurement facility to study the ionosphere. The plasma lines are not routinely detected by the incoherent scatter radar due to the low intensity, which falls below the measured spectral noise level of the incoherent scatter radar. The plasma lines are occasionally enhanced by suprathermal electrons through the Landau damping process and detectable to the incoherent scatter radar. In this study, by using the European Incoherent Scatter Association (EISCAT) UHF incoherent scatter radar, the experiment observation presents that the enhanced plasma lines were observed. These plasma lines were considered as manifest of the suprathermal electrons generated by the high-frequency heating wave during the ionospheric modification. The electron density profile is also obtained from the enhanced plasma lines. This study can be a promising technique for obtaining the accurate electron density during ionospheric modification experiment.

Application of reflectometry power flow for magnetic field pitch angle measurements in tokamak plasmas (invited).

PubMed

Gourdain, P-A; Peebles, W A

2008-10-01

Reflectometry has successfully demonstrated measurements of many important parameters in high temperature tokamak fusion plasmas. However, implementing such capabilities in a high-field, large plasma, such as ITER, will be a significant challenge. In ITER, the ratio of plasma size (meters) to the required reflectometry source wavelength (millimeters) is significantly larger than in existing fusion experiments. This suggests that the flow of the launched reflectometer millimeter-wave power can be realistically analyzed using three-dimensional ray tracing techniques. The analytical and numerical studies presented will highlight the fact that the group velocity (or power flow) of the launched microwaves is dependent on the direction of wave propagation relative to the internal magnetic field. It is shown that this dependence strongly modifies power flow near the cutoff layer in a manner that embeds the local magnetic field direction in the "footprint" of the power returned toward the launch antenna. It will be shown that this can potentially be utilized to locally determine the magnetic field pitch angle at the cutoff location. The resultant beam drift and distortion due to magnetic field and relativistic effects also have significant consequences on the design of reflectometry systems for large, high-field fusion experiments. These effects are discussed in the context of the upcoming ITER burning plasma experiment.

Disruption avoidance by means of electron cyclotron waves

NASA Astrophysics Data System (ADS)

Esposito, B.; Granucci, G.; Maraschek, M.; Nowak, S.; Lazzaro, E.; Giannone, L.; Gude, A.; Igochine, V.; McDermott, R.; Poli, E.; Reich, M.; Sommer, F.; Stober, J.; Suttrop, W.; Treutterer, W.; Zohm, H.; ASDEX Upgrade, the; FTU Teams

2011-12-01

Disruptions are very challenging to ITER operation as they may cause damage to plasma facing components due to direct plasma heating, forces on structural components due to halo and eddy currents and the production of runaway electrons. Electron cyclotron (EC) waves have been demonstrated as a tool for disruption avoidance by a large set of recent experiments performed in ASDEX Upgrade and FTU using various disruption types, plasma operating scenarios and power deposition locations. The technique is based on the stabilization of magnetohydrodynamic (MHD) modes (mainly m/n = 2/1) through the localized injection of EC power on the resonant surface. This paper presents new results obtained in ASDEX Upgrade regarding stable operation above the Greenwald density achieved after avoidance of density limit disruptions by means of ECRH and suitable density feedback control (L-mode ohmic plasmas, Ip = 0.6 MA, Bt = 2.5 T) and NTM-driven disruptions at high-β limit delayed/avoided by means of both co-current drive (co-ECCD) and pure heating (ECRH) with power <=1.7 MW (H-mode NBI-heated plasmas, PNBI ~ 7.5 MW, Ip = 1 MA, Bt = 2.1 T, q95 ~ 3.6). The localized perpendicular injection of ECRH/ECCD onto a resonant surface leads to the delay and/or complete avoidance of disruptions. The experiments indicate the existence of a power threshold for mode stabilization to occur. An analysis of the MHD mode evolution using the generalized Rutherford equation coupled to the frequency and phase evolution equations shows that control of the modes is due to EC heating close to the resonant surface. The ECRH contribution (Δ'H term) is larger than the co-ECCD one in the initial and more important phase when the discharge is 'saved'. Future research and developments of the disruption avoidance technique are also discussed.

Measurements of plasma loading in the presence of electrostatic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riccardi, C.; Agostini, E.; Fontanesi, M.

1995-10-01

An experimental analysis of the plasma impedance with respect to the coupling of ES (electrostatic) waves is described in this paper. The waves are excited through a slow-wave antenna and the experiment performed in a toroidal device [C. Riccardi {ital et} {ital al}., Plasma Phys. {bold 36}, 1791 (1994)]. The measured impedance is compared with a simple theoretical model for magnetized homogeneous plasma, in order to establish the presence of bulk or surface waves and of some nonlinear effects when power is raised. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Applying the cold plasma dispersion relation to whistler mode chorus waves: EMFISIS wave measurements from the Van Allen Probes

DOE PAGES

Hartley, D. P.; Chen, Y.; Kletzing, C. A.; ...

2015-01-26

Most theoretical wave models require the power in the wave magnetic field in order to determine the effect of chorus waves on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic wave power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and magnetic spectral intensities in the chorus wave band (0.1–0.9 f ce). Results from this study indicate that the calculatedmore » wave intensity is least accurate during periods of enhanced wave activity. For observed wave intensities >10⁻³ nT², using the cold plasma dispersion relation results in an underestimate of the wave intensity by a factor of 2 or greater 56% of the time over the full chorus wave band, 60% of the time for lower band chorus, and 59% of the time for upper band chorus. Hence, during active periods, empirical chorus wave models that are reliant on the cold plasma dispersion relation will underestimate chorus wave intensities to a significant degree, thus causing questionable calculation of wave-particle resonance effects on MeV electrons.« less

Characteristics of solitary waves in a relativistic degenerate ion beam driven magneto plasma

NASA Astrophysics Data System (ADS)

Deka, Manoj Kr.; Dev, Apul N.; Misra, Amar P.; Adhikary, Nirab C.

2018-01-01

The nonlinear propagation of a small amplitude ion acoustic solitary wave in a relativistic degenerate magneto plasma in the presence of an ion beam is investigated in detail. The nonlinear equations describing the evolution of a solitary wave in the presence of relativistic non-degenerate magnetized positive ions and ion beams including magnetized degenerate relativistic electrons are derived in terms of Zakharov-Kuznetsov (Z-K) equation for such plasma systems. The ion beams which are a ubiquitous ingredient in such plasma systems are found to have a decisive role in the propagation of a solitary wave in such a highly dense plasma system. The conditions of a wave, propagating with typical solitonic characteristics, are examined and discussed in detail under suitable conditions of different physical parameters. Both a subsonic and supersonic wave can propagate in such plasmas bearing different characteristics under different physical situations. A detailed analysis of waves propagating in subsonic and/or supersonic regime is carried out. The ion beam concentrations, magnetic field, as well as ion beam streaming velocity are found to play a momentous role on the control of the amplitude and width of small amplitude perturbation in both weakly (or non-relativistic) and relativistic plasmas.

ISIS Topside-Sounder Plasma-Wave Investigations as Guides to Desired Virtual Wave Observatory (VWO) Data Search Capabilities

NASA Technical Reports Server (NTRS)

Benson, Robert F.; Fung, Shing F.

2008-01-01

Many plasma-wave phenomena, observed by space-borne radio sounders, cannot be properly explained in terms of wave propagation in a cold plasma consisting of mobile electrons and infinitely massive positive ions. These phenomena include signals known as plasma resonances. The principal resonances at the harmonics of the electron cyclotron frequency, the plasma frequency, and the upper-hybrid frequency are well explained by the warm-plasma propagation of sounder-generated electrostatic waves, Other resonances have been attributed to sounder-stimulated plasma instability and non-linear effects, eigenmodes of cylindrical electromagnetic plasma oscillations, and plasma memory processes. Data from the topside sounders of the International Satellites for Ionospheric Studies (ISIS) program played a major role in these interpretations. A data transformation and preservation effort at the Goddard Space Flight Center has produced digital ISIS topside ionograms and a metadata search program that has enabled some recent discoveries pertaining to the physics of these plasma resonances. For example, data records were obtained that enabled the long-standing question (several decades) of the origin of the plasma resonance at the fundamental electron cyclotron frequency to be explained [Muldrew, Radio Sci., 2006]. These data-search capabilities, and the science enabled by them, will be presented as a guide to desired data search capabilities to be included in the Virtual Wave Observatory (VWO).

Alfven wave dispersion behavior in single- and multicomponent plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahbarnia, K.; Grulke, O.; Klinger, T.

Dispersion relations of driven Alfven waves (AWs) are measured in single- and multicomponent plasmas consisting of mixtures of argon, helium, and oxygen in a magnetized linear cylindrical plasma device VINETA [C. Franck, O. Grulke, and T. Klinger, Phys. Plasmas 9, 3254 (2002)]. The decomposition of the measured three-dimensional magnetic field fluctuations and the corresponding parallel current pattern reveals that the wave field is a superposition of L- and R-wave components. The dispersion relation measurements agree well with calculations based on a multifluid Hall-magnetohydrodynamic model if the plasma resistivity is correctly taken into account.

Propagation of electromagnetic wave in dusty plasma and the influence of dust size distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hui; China Research Institute of Radio Wave Propagation; Wu, Jian

The effect of charged dust particle and their size distribution on the propagation of electromagnetic wave in a dusty plasma is investigated. It is shown that the additional collision mechanism provided by charged dust particles can significantly alter the electromagnetic properties of a plasma, leading to the appearance of attenuation of electromagnetic wave through dusty plasma. The attenuation coefficient mainly depends on the dust density, radius, and the charge numbers on the dust surface. The results described here will be used to enhance understanding of electromagnetic wave propagation processed in space and laboratory dusty plasma.

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

PubMed

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

2015-12-09

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.

Ultralow frequency waves in the magnetotails of the earth and the outer planets

NASA Technical Reports Server (NTRS)

Khurana, Krishan K.; Chen, Sheng H.; Hammond, C. M.; Kivelson, Margaret G.

1992-01-01

Ultralow frequency waves with periods greater than two minutes are characteristic features of planetary magnetotails. At Jupiter, changes in the wave characteristics across the boundary between the plasma sheet and the lobe have been used to identify this important plasma boundary. In the terrestrial lobes the wave amplitude can be relatively large, especially during intervals of intense geomagnetic activity. The wave power seen in the lobes of the magnetotails of the earth, Jupiter, Saturn and Uranus is evaluated to evaluate a proposal by Smith et al. that the propagating waves generated by the Kelvin-Helmholtz instability on the magnetopause can heat the plasma through a resonant absorption of these waves. The results indicate that the wave power in the lobes is generally small and can be easily understood in the framework of coupled MHD waves generated in the plasma sheet.

Nonlinear Alfvén wave propagating in ideal MHD plasmas

NASA Astrophysics Data System (ADS)

Zheng, Jugao; Chen, Yinhua; Yu, Mingyang

2016-01-01

The behavior of nonlinear Alfvén waves propagating in ideal MHD plasmas is investigated numerically. It is found that in a one-dimensional weakly nonlinear system an Alfvén wave train can excite two longitudinal disturbances, namely an acoustic wave and a ponderomotively driven disturbance, which behave differently for β \\gt 1 and β \\lt 1, where β is the ratio of plasma-to-magnetic pressures. In a strongly nonlinear system, the Alfvén wave train is modulated and can steepen to form shocks, leading to significant dissipation due to appearance of current sheets at magnetic-pressure minima. For periodic boundary condition, we find that the Alfvén wave transfers its energy to the plasma and heats it during the shock formation. In two-dimensional systems, fast magneto-acoustic wave generation due to Alfvén wave phase mixing is considered. It is found that the process depends on the amplitude and frequency of the Alfvén waves, as well as their speed gradients and the pressure of the background plasma.

Polar Plasma Wave Investigation Data Analysis in the Extended Mission

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.; Menietti, J. D.

2003-01-01

The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to l0(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross- diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes.

Polar Plasma Wave Investigation Data Analysis in the Extended Mission

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

2004-01-01

The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to 10(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross-diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes.

Ionization Waves of Arbitrary Velocity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turnbull, D.; Franke, P.; Katz, J.

The flying focus is a technique in which a chirped laser beam is focused by a chromatic lens to produce an extended focal spot within which laser intensity can propagate at any velocity. If the intensity is above the ionization threshold of a background gas, an ionization wave will track the ionization threshold intensity isosurface as it propagates. We report on the demonstration of such ionization waves of arbitrary velocity. Subluminal and superluminal ionization fronts were produced, both forward- and backward-propagating relative to the ionizing laser. In conclusion, all backward and all superluminal cases mitigated the issue of ionization-induced refractionmore » that typically challenges the formation of long, contiguous plasma channels.« less

Ionization Waves of Arbitrary Velocity

DOE PAGES

Turnbull, D.; Franke, P.; Katz, J.; ...

2018-05-31

The flying focus is a technique in which a chirped laser beam is focused by a chromatic lens to produce an extended focal spot within which laser intensity can propagate at any velocity. If the intensity is above the ionization threshold of a background gas, an ionization wave will track the ionization threshold intensity isosurface as it propagates. We report on the demonstration of such ionization waves of arbitrary velocity. Subluminal and superluminal ionization fronts were produced, both forward- and backward-propagating relative to the ionizing laser. In conclusion, all backward and all superluminal cases mitigated the issue of ionization-induced refractionmore » that typically challenges the formation of long, contiguous plasma channels.« less

Nonthermal and geometric effects on the symmetric and anti-symmetric surface waves in a Lorentzian dusty plasma slab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791

2015-02-15

The nonthermal and geometric effects on the propagation of the surface dust acoustic waves are investigated in a Lorentzian dusty plasma slab. The symmetric and anti-symmetric dispersion modes of the dust acoustic waves are obtained by the plasma dielectric function with the spectral reflection conditions the slab geometry. The variation of the nonthermal and geometric effects on the symmetric and the anti-symmetric modes of the surface plasma waves is also discussed.

Analysis of long wavelength electromagnetic scattering by a magnetized cold plasma prolate spheroid

NASA Astrophysics Data System (ADS)

Ahmadizadeh, Yadollah; Jazi, Bahram; Abdoli-Arani, Abbas

2013-08-01

Using dielectric permittivity tensor of the magnetized prolate plasma, the scattering of long wavelength electromagnetic waves from the mentioned object is studied. The resonance frequency and differential scattering cross section for the backward scattered waves are presented. Consistency between the resonance frequency in this configuration and results obtained for spherical plasma are investigated. Finally, the effective factors on obtained results such as incident wave polarization, the frequency of the incident wave, the plasma frequency and the cyclotron frequency are analyzed.

Wave-particle and wave-wave interactions in hot plasmas: a French historical point of view

NASA Astrophysics Data System (ADS)

Laval, Guy; Pesme, Denis; Adam, Jean-Claude

2016-11-01

The first researches on nuclear fusion for energy applications marked the entrance of hot plasmas into the laboratory. It became necessary to understand the behavior of such plasmas and to learn how to manipulate them. Theoreticians and experimentalists, building on the foundations of empirical laws, had to construct this new plasma physics from first principles and to explain the results of more and more complicated experiments. Along this line, two important topics emerged: wave-particle and wave-wave interactions. Here, their history is recalled as it has been lived by a French team from the end of the sixties to the beginning of the twenty-first century.

Landau damping in space plasmas

NASA Technical Reports Server (NTRS)

Thorne, Richard M.; Summers, Danny

1991-01-01

The Landau damping of electrostatic Langmuir waves and ion-acoustic waves in a hot, isotropic, nonmagnetized, generalized Lorentzian plasma is analyzed using the modified plasma dispersion function. Numerical solutions for the real and imaginary parts of the wave frequency omega sub 0 - (i)(gamma) have been obtained as a function of the normalized wave number (k)(lambda sub D), where lambda sub D is the electron Debye length. For both particle distributions the electrostatic modes are found to be strongly damped at short wavelengths. At long wavelengths, this damping becomes less severe, but the attenuation of Langmuir waves is much stronger for a generalized Lorentzian plasma than for a Maxwellian plasma. It is concluded that Landau damping of ion-acoustic waves is only slightly affected by the presence of a high energy tail, but is strongly dependent on the ion temperature.

Jupiter Data Analysis Program: Analysis of Voyager wideband plasma wave observations

NASA Technical Reports Server (NTRS)

Kurth, W. S.

1983-01-01

Voyager plasma wave wideband frames from the Jovian encounters are analyzed. The 511 frames which were analyzed were chosen on the basis of low-rate spectrum analyzer data from the plasma wave receiver. These frames were obtained in regions and during times of various types of plasma or radio wave activity as determined by the low-rate, low-resolution data and were processed in order to provide high resolution measurements of the plasma wave spectrum for use in the study of a number of outstanding problems. Chorus emissions at Jupiter were analyzed. The detailed temporal and spectral form of the very complex chorus emissions near L = 8 on the Voyager 1 inbound passage was compared to both terrestrial chorus emissions as well as to the theory which was developed to explain the terrestrial waves.

The effect of plasma inhomogeneities on (i) radio emission generation by non-gyrotropic electron beams and (ii) particle acceleration by Langmuir waves

NASA Astrophysics Data System (ADS)

Tsiklauri, David

2015-04-01

Extensive particle-in-cell simulations of fast electron beams injected in a background magnetised plasma with a decreasing density profile were carried out. These simulations were intended to further shed light on a newly proposed mechanism for the generation of electromagnetic waves in type III solar radio bursts [1]. Here recent progress in an alternative to the plasma emission model using Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts will be presented. In particular, (i) Fourier space drift (refraction) of non-gyrotropic electron beam-generated wave packets, caused by the density gradient [1,2], (ii) parameter space investigation of numerical runs [3], (iii) concurrent generation of whistler waves [4] and a separate problem of (iv) electron acceleration by Langmuir waves in a background magnetised plasma with an increasing density profile [5] will be discussed. In all considered cases the density inhomogeneity-induced wave refraction plays a crucial role. In the case of non-gyrotropic electron beam, the wave refraction transforms the generated wave packets from standing into freely escaping EM radiation. In the case of electron acceleration by Langmuir waves, a positive density gradient in the direction of wave propagation causes a decrease in the wavenumber, and hence a higher phase velocity vph = ω/k. The k-shifted wave is then subject to absorption by a faster electron by wave-particle interaction. The overall effect is an increased number of high energy electrons in the energy spectrum. [1] D. Tsiklauri, Phys. Plasmas 18, 052903 (2011); http://dx.doi.org/10.1063/1.3590928 [2] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013); http://dx.doi.org/10.1063/1.4812453 [3] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012); http://dx.doi.org/10.1063/1.4768429 [4] M. Skender, D. Tsiklauri, Phys. Plasmas 21, 042904 (2014); http://dx.doi.org/10.1063/1.4871723 [5] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 21, 012903 (2014); http://dx.doi.org/10.1063/1.4863494 This research is funded by the Leverhulme Trust Research Project Grant RPG-311

Far infrared diagnostics of electron concentration in combustion MHD plasmas using interferometry and Faraday rotation

NASA Astrophysics Data System (ADS)

Kuzmenko, P. J.

1985-12-01

The plasma electrical conductivity is a key parameter in determining the efficiency of an magnetohydrodynamic (MHD) generator. Electromagnetic waves offer an accurate, non-intrusive probe. The electron concentration and mobility may be deduced from the refractive index and absorption coefficient measured with an interferometer. The first experiment used an HCOOH laser at 393.6 microns feeding a Michelson interferometer mounted around a combustor duct with open ports. Simultaneous measurements of positive ion density and plasma temperature made with a Langmuir probe and line reversal apparatus verified the operation of the interferometer. With a magnetic field present, measurement of the polarization rotation and induced ellipticity in a wave traveling along the field provides information on the plasma conductivity. Compared to interferometry, diagnostic apparatus based on Faraday rotation offers simpler optics and requires far less stringent mechanical stability at a cost of lower sensitivity. An advanced detection scheme, using a polarizing beam splitter improved the sensitivity to be comparable to that of interferometry. Interferometry is the preferred technique for small scale, high accuracy measurements, with Faraday rotation reserved for large systems or measurements within a working generator.

Low-temperature graphene synthesis using microwave plasma CVD

NASA Astrophysics Data System (ADS)

Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

2013-02-01

The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 105 Ω/sq.

Solar system plasma waves

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

1995-01-01

An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

Plasma waves in the magnetic hole

NASA Technical Reports Server (NTRS)

Lin, Naiguo; Kellogg, P. J.; MacDowall, R.; Balogh, A.; Forsyth, R. J.; Phillips, J. L.; Pick, M.

1995-01-01

Magnetic holes in the solar wind, which are characterized by isolated local depressions in the magnetic field magnitude, have been observed previously. The Unified Radio and Plasma Wave (URAP) instrument of Ulysses has found that within such magnetic structures, electrostatic waves at kHz frequency and ultralow frequency electromagnetic waves are often excited and seen as short duration wave bursts. Most of these bursts occur near the ambient electron plasma frequency, which suggests that the waves are Langmuir waves. Such waves are usually excited by electron streams. Some evidence of the streaming of energetic electrons required for exciting Langmuir waves has been observed. These electrons may have originated at sources near the Sun, which would imply that the magnetic structures containing the waves would exist as long channels formed by field and plasma conditions near the Sun. On the other hand, the electrons could be suprathermal 'tails' from wave collapse processes occurring near the spacecraft. In either case, the Langmuir waves excited in the magnetic holes provide a measurement of the plasma density inside the holes. Low frequency electromagnetic waves, having frequencies of a fraction of the local electron cyclotron frequency, sometimes accompany the Langmuir waves observed in magnetic holes. Waves excited in this frequency range are very likely to be whistler-mode waves. They may have been excited by an electron temperature anisotropy which has been observed in the vicinity of the magnetic holes or generated through the decay of Langmuir waves.

Dissipation of Alfven Waves at Fluid Scale through Parametric Decay Instabilities in Low-beta Turbulent Plasma

NASA Astrophysics Data System (ADS)

Fu, X.; Li, H.; Guo, F.; Li, X.; Roytershteyn, V.

2017-12-01

The solar wind is a turbulent magnetized plasma extending from the upper atmosphere of the sun to the edge of the heliosphere. It carries charged particles and magnetic fields originated from the Sun, which have great impact on the geomagnetic environment and human activities in space. In such a magnetized plasma, Alfven waves play a crucial role in carrying energy from the surface of the Sun, injecting into the solar wind and establishing power-law spectra through turbulent energy cascades. On the other hand, in compressible plasmas large amplitude Alfven waves are subject to a parametric decay instability (PDI) which converts an Alfven wave to another counter-propagating Alfven wave and an ion acoustic wave (slow mode). The counter-propagating Alfven wave provides an important ingredient for turbulent cascade, and the slow-mode wave provides a channel for solar wind heating in a spatial scale much larger than ion kinetic scales. Growth and saturation of PDI in quiet plasma have been intensively studied using linear theory and nonlinear simulations in the past. Here using 3D hybrid simulations, we show that PDI is still effective in turbulent low-beta plasmas, generating slow modes and causing ion heating. Selected events in WIND data are analyzed to identify slow modes in the solar wind and the role of PDI, and compared with our simulation results. We also investigate the validity of linear Vlasov theory regarding PDI growth and slow mode damping in turbulent plasmas. Since PDI favors low plasma beta, we expect to see more evidence of PDI in the solar wind close to the Sun, especially from the upcoming NASA's Parker Solar Probe mission which will provide unprecedented wave and plasma data as close as 8.5 solar radii from the Sun.

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.

Intense plasma waves at and near the solar wind termination shock.

PubMed

Gurnett, D A; Kurth, W S

2008-07-03

Plasma waves are a characteristic feature of shocks in plasmas, and are produced by non-thermal particle distributions that develop in the shock transition layer. The electric fields of these waves have a key role in dissipating energy in the shock and driving the particle distributions back towards thermal equilibrium. Here we report the detection of intense plasma-wave electric fields at the solar wind termination shock. The observations were obtained from the plasma-wave instrument on the Voyager 2 spacecraft. The first evidence of the approach to the shock was the detection of upstream electron plasma oscillations on 1 August 2007 at a heliocentric radial distance of 83.4 au (1 au is the Earth-Sun distance). These narrowband oscillations continued intermittently for about a month until, starting on 31 August 2007 and ending on 1 September 2007, a series of intense bursts of broadband electrostatic waves signalled a series of crossings of the termination shock at a heliocentric radial distance of 83.7 au. The spectrum of these waves is quantitatively similar to those observed at bow shocks upstream of Jupiter, Saturn, Uranus and Neptune.

Dust acoustic solitary waves in a dusty plasma with two kinds of nonthermal ions at different temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorranian, Davoud; Sabetkar, Akbar

The nonlinear dust acoustic solitary waves in a dusty plasma with two nonthermal ion species at different temperatures is studied analytically. Using reductive perturbation method, the Kadomtsev-Petviashivili (KP) equation is derived, and the effects of nonthermal coefficient, ions temperature, and ions number density on the amplitude and width of soliton in dusty plasma are investigated. It is shown that the amplitude of solitary wave of KP equation diverges at critical points of plasma parameters. The modified KP equation is also derived, and from there, the soliton like solutions of modified KP equation with finite amplitude is extracted. Results show thatmore » generation of rarefactive or compressive solitary waves strongly depends on the number and temperature of nonthermal ions. Results of KP equation confirm that for different magnitudes of ions temperature (mass) and number density, mostly compressive solitary waves are generated in a dusty plasma. In this case, the amplitude of solitary wave is decreased, while the width of solitary waves is increased. According to the results of modified KP equation for some certain magnitudes of parameters, there is a condition for generation of an evanescent solitary wave in a dusty plasma.« less

Research on radiation characteristic of plasma antenna through FDTD method.

PubMed

Zhou, Jianming; Fang, Jingjing; Lu, Qiuyuan; Liu, Fan

2014-01-01

The radiation characteristic of plasma antenna is investigated by using the finite-difference time-domain (FDTD) approach in this paper. Through using FDTD method, we study the propagation of electromagnetic wave in free space in stretched coordinate. And the iterative equations of Maxwell equation are derived. In order to validate the correctness of this method, we simulate the process of electromagnetic wave propagating in free space. Results show that electromagnetic wave spreads out around the signal source and can be absorbed by the perfectly matched layer (PML). Otherwise, we study the propagation of electromagnetic wave in plasma by using the Boltzmann-Maxwell theory. In order to verify this theory, the whole process of electromagnetic wave propagating in plasma under one-dimension case is simulated. Results show that Boltzmann-Maxwell theory can be used to explain the phenomenon of electromagnetic wave propagating in plasma. Finally, the two-dimensional simulation model of plasma antenna is established under the cylindrical coordinate. And the near-field and far-field radiation pattern of plasma antenna are obtained. The experiments show that the variation of electron density can introduce the change of radiation characteristic.

In situ measurement of plasma and shock wave properties inside laser-drilled metal holes

NASA Astrophysics Data System (ADS)

Brajdic, Mihael; Hermans, Martin; Horn, Alexander; Kelbassa, Ingomar

2008-10-01

High-speed imaging of shock wave and plasma dynamics is a commonly used diagnostic method for monitoring processes during laser material treatment. It is used for processes such as laser ablation, cutting, keyhole welding and drilling. Diagnosis of laser drilling is typically adopted above the material surface because lateral process monitoring with optical diagnostic methods inside the laser-drilled hole is not possible due to the hole walls. A novel method is presented to investigate plasma and shock wave properties during the laser drilling inside a confined environment such as a laser-drilled hole. With a novel sample preparation and the use of high-speed imaging combined with spectroscopy, a time and spatial resolved monitoring of plasma and shock wave dynamics is realized. Optical emission of plasma and shock waves during drilling of stainless steel with ns-pulsed laser radiation is monitored and analysed. Spatial distributions and velocities of shock waves and of plasma are determined inside the holes. Spectroscopy is accomplished during the expansion of the plasma inside the drilled hole allowing for the determination of electron densities.

Spatial distribution of the wave field of the surface modes sustaining filamentary discharges

NASA Astrophysics Data System (ADS)

Lishev, St.; Shivarova, A.; Tarnev, Kh.

2008-01-01

The study presents the electrodynamical description of surface-wave-sustained discharges contracted in filamentary structures. The results are for the spatial distribution of the wave field and for the wave propagation characteristics obtained from a two-dimensional model developed for describing surface-wave behavior in plasmas with an arbitrary distribution of the plasma density. In accordance with the experimental observations of filamentary discharges, the plasma density distribution considered is completed by cylindrically shaped gas-discharge channels extended along the discharge length and positioned in the out-of-center region of the discharge, equidistantly in an azimuthal direction. Due to the two-dimensional inhomogeneity of the plasma density of the filamentary structure, the eigen surface mode of the structure is a hybrid wave, with all—six—field components. For identification of its behavior, the surface wave properties in the limiting cases of a plasma ring and a single filament—both radially inhomogeneous—are involved in the discussions. The presentation of the results is for filamentary structures with a decreasing number of filaments (from 10 to 2) starting with the plasma ring, the latter supporting propagation of an azimuthally symmetric wave. Due to the resonance absorption of the surface waves, always present because of the smooth variation of the plasma density, the contours of the critical density are those guiding the surface wave propagation. Decreasing number of filaments in the structure leads to localization of the amplitudes of the wave-field components around the filaments. By analogy with the spatial distribution of the wave field in the plasma ring, the strong resonance enhancement of the wave-field components is along that part of the contour of the critical density which is far off the center of the filamentary structure. The analysis of the spatial distribution of the field components of the filamentary structure shows that the hybrid wave is an eigenmode of the whole structure, i.e., the wave field does not appear as a superposition of fields of eigenmodes of the separated filaments completing it. It is stressed that the spatial distribution of the field components of the eigen hybrid mode of the filamentary structure has an azimuthally symmetric background field.

Determination of HF artificial ionospheric turbulence characteristics using comparison of calculated plasma wave decay rates with the measured see decay rates

NASA Astrophysics Data System (ADS)

Grach, Savely; Bareev, Denis; Gavrilenko, Vladimir; Sergeev, Evgeny

Damping rates of plasma waves with ω ˜ ωuh (ω is the plasma wave frequency, ωuh is the upper hybrid frequency) were calculated for frequencies close to and distant from the double resonance where ωuh ˜ nωce (ωce is the electron cyclotron frequency, n=4,5 are the gyroharmonic num-bers). The calculations were performed numerically on the base of full plasma wave dispersion relation not restricted by both the 'long wave limit' and 'short wave limit', i.e. a fulfillment of the inequalities |∆| |k |vTe and |∆| |k |vTe was not required. Here ∆ = ω - nωce , vTe = (Te /me )1/2 is the electron thermal velocity and k is the projection of the wave vector onto the magnetic field direction. It is shown that the plasma wave damping rates do not differ noticeably from ones calculated under the long wave and short wave limits. The results obtained are compared with the data of the relaxation of the stimulated electromagnetic emission (SEE) after the pump wave turn off, which demonstrate an essential decrease of the relaxation time near 4th electron gyroharmonic, so far as the SEE relaxation is attributed to the damping of plasma waves responsible for the SEE generation. The comparison allows to determine characteristics of plasma waves mostly contributing to the SEE generation, such as wave numbers and the angles between the wave vectors and geomagnetic field, and the altitude region of the SEE source. The dependence of the decay rate on ∆ can be applied also to interpretation of the SEE spectral shape at different pump frequencies near gyroharmonics. The work is supported by RFBR grants 10-02-00642, 09-02-01150 and Federal Special-purpose Program "Scientific and pedagogical personnel of innovative Russia".

Nonlinear Right-Hand Polarized Wave in Plasma in the Electron Cyclotron Resonance Region

NASA Astrophysics Data System (ADS)

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

2018-05-01

The propagation of a nonlinear right-hand polarized wave along an external magnetic field in subcritical plasma in the electron cyclotron resonance region is studied using numerical simulations. It is shown that a small-amplitude plasma wave excited in low-density plasma is unstable against modulation instability with a modulation period equal to the wavelength of the excited wave. The modulation amplitude in this case increases with decreasing detuning from the resonance frequency. The simulations have shown that, for large-amplitude waves of the laser frequency range propagating in plasma in a superstrong magnetic field, the maximum amplitude of the excited longitudinal electric field increases with the increasing external magnetic field and can reach 30% of the initial amplitude of the electric field in the laser wave. In this case, the energy of plasma electrons begins to substantially increase already at magnetic fields significantly lower than the resonance value. The laser energy transferred to plasma electrons in a strong external magnetic field is found to increase severalfold compared to that in isotropic plasma. It is shown that this mechanism of laser radiation absorption depends only slightly on the electron temperature.

Electromagnetic radiation from beam-plasma instabilities

NASA Technical Reports Server (NTRS)

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

1982-01-01

The mechanism by which unstable electrostatic waves of an electron-beam plasma system are converted into observed electromagnetic waves is of great current interest in space plasma physics. Electromagnetic radiation arises from both natural beam-plasma systems, e.g., type III solar bursts and kilometric radiation, and from man-made electron beams injected from rockets and spacecraft. In the present investigation the diagnostic difficulties encountered in space plasmas are overcome by using a large laboratory plasma. A finite diameter (d approximately equal to 0.8 cm) electron beam is injected into a uniform quiescent magnetized afterglow plasma of dimensions large compared with electromagnetic wavelength. Electrostatic waves grow, saturate and decay within the uniform central region of the plasma volume so that linear mode conversion on density gradients can be excluded as a possible generation mechanism for electromagnetic waves.

Current driven instabilities of an electromagnetically accelerated plasma

NASA Technical Reports Server (NTRS)

Chouetri, E. Y.; Kelly, A. J.; Jahn, R. G.

1988-01-01

A plasma instability that strongly influences the efficiency and lifetime of electromagnetic plasma accelerators was quantitatively measured. Experimental measurements of dispersion relations (wave phase velocities), spatial growth rates, and stability boundaries are reported. The measured critical wave parameters are in excellent agreement with theoretical instability boundary predictions. The instability is current driven and affects a wide spectrum of longitudinal (electrostatic) oscillations. Current driven instabilities, which are intrinsic to the high-current-carrying magnetized plasma of the magnetoplasmadynmic (MPD) accelerator, were investigated with a kinetic theoretical model based on first principles. Analytical limits of the appropriate dispersion relation yield unstable ion acoustic waves for T(i)/T(e) much less than 1 and electron acoustic waves for T(i)/T(e) much greater than 1. The resulting set of nonlinear equations for the case of T(i)/T(e) = 1, of most interest to the MPD thruster Plasma Wave Experiment, was numerically solved to yield a multiparameter set of stability boundaries. Under certain conditions, marginally stable waves traveling almost perpendicular to the magnetic field would travel at a velocity equal to that of the electron current. Such waves were termed current waves. Unstable current waves near the upper stability boundary were observed experimentally and are in accordance with theoretical predictions. This provides unambiguous proof of the existence of such instabilites in electromagnetic plasma accelerators.

Electron Acoustic Waves in Pure Ion Plasmas

NASA Astrophysics Data System (ADS)

Anderegg, F.; Driscoll, C. F.; Dubin, D. H. E.; O'Neil, T. M.

2009-11-01

Electron Acoustic Waves (EAW) are the low frequency branch of electrostatic plasma waves. These waves exist in neutralized plasmas, pure electron plasmas and in pure ion plasmasfootnotetextF. Anderegg et al., PRL 102, 095001 (2009) and PoP 16, 055705 (2009). (where the name is deceptive). Here, we observe standing mθ= 0 mz= 1 EAWs in a pure ion plasma column. At small amplitude, the EAWs have a phase velocity vph ˜1.4 v, and the frequencies are in close agreement with theory. At moderate amplitudes, waves can be excited over a broad range of frequencies, with observed phase velocities in the range of 1.4 v <=vph <=2.1 v. This frequency variability comes from the plasma adjusting its velocity distribution so as to make the EAW resonant with the drive frequency. Our wave-coherent laser-induced fluorescence diagnostic shows that particles slower than vph oscillate in phase with the wave, while particles moving faster than vph oscillate 180^o out of phase with the wave. From a fluid perspective, this gives an unusual negative dynamical compressibility. That is, the wave pressure oscillations are 180^o out of phase from the density oscillations, almost fully canceling the electrostatic restoring force, giving the low and malleable frequency.

Salient features of solitary waves in dusty plasma under the influence of Coriolis force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, G. C.; Nag, Apratim; Department of Physics, G. C. College, Silchar-788004

The main interest is to study the nonlinear acoustic wave in rotating dusty plasma augmented through the derivation of a modified Sagdeev potential equation. Small rotation causes the interaction of Coriolis force in the dynamical system, and leads to the complexity in the derivation of the nonlinear wave equation. As a result, the finding of solitary wave propagation in dusty plasma ought to be of merit. However, the nonlinear wave equation has been successfully solved by the use of the hyperbolic method. Main emphasis has been given to the changes on the evolution and propagation of soliton, and the variationmore » caused by the dusty plasma constituents as well as by the Coriolis force have been highlighted. Some interesting nonlinear wave behavior has been found which can be elaborately studied for the interest of laboratory and space plasmas. Further, to support the theoretical investigations, numeric plasma parameters have been taken for finding the inherent features of solitons.« less

Development of Electric Field and Plasma Wave Investigations for Future Space Weather Missions: ERG, SCOPE, and beyond

NASA Astrophysics Data System (ADS)

Kasaba, Y.; Kumamoto, A.; Ono, T.; Misawa, H.; Kojima, H.; Yagitani, S.; Kasahara, Y.; Ishisaka, K.

2009-04-01

The electric field and plasma wave investigation is important for the clarification of global plasma dynamics and energetic processes in the planetary Magnetospheric studies. We have several missions which will contribute those objectives. the small-sized radiation belt mission, ERG (Energization and Radiation in Geospace), the cross-scale formation flight mission, SCOPE, the BepiColombo mission to Mercury, and the small-sized and full-scale Jovian mission in future. Those will prevail the universal plasma mechanism and processes in the space laboratory. The main purposes of electric field and plasma wave observation for those missions are: (1) Examination of the theories of high-energy particle acceleration by plasma waves, (2) identification of the origin of electric fields in the magnetosphere associated with cross-scale coupling processes, (3) diagnosis of plasma density, temperature and composition, and (4) investigation of wave-particle interaction and mode conversion processes. Simultaneous observation of plasma waves and energetic particles with high resolution will enable us to investigate the wave-particle interaction based on quasi-linear theory and non-linear models. In this paper, we will summarize the current plan and efforts for those future activities. In order to achieve those objectives, the instrument including sensitive sensors (the long wire / stem antennae, the search-coil / loop antennae) and integrated receiver systems are now in development, including the direct identification of nonlinear wave-particle interactions associated will be tried by Wave-particle Correlator. And, as applications of those development, we will mention to the space interferometer and the radar sounder technologies.

FOREWORD: Workshop on Large Amplitude Waves and Fields in Plasmas, sponsored by the Commission of the European Communities

NASA Astrophysics Data System (ADS)

Bingham, R.; De Angelis, U.; Shukla, P. K.; Stenflo, L.

1990-01-01

During the last decade considerable progress has been made in the area of nonlinear plasma wave phenomena and their applications. In order to exhibit the present state-of-art in this field, a one-week (22-26 May) workshop on Large Amplitude Waves and Fields was organized at the International Centre for Theoretical Physics (ICTP), Trieste, Italy, during the bi-yearly activity of the Spring College on Plasma Physics (15 May-9 June, 1989). Most of the invited lectures are published in this Topical Issue of Physica Scripta so that scientists working, or who want to enter the field of nonlinear plasma wave theory, can find out what has been achieved and what are the current research trends in this area. The material included here consists of general plasma wave theory, results of computer simulations, and experimental verifications. Without going into any detail, we shall just highlight the topics and the general features of the lectures contained in these proceedings. Various aspects of the excitation, propagation and interaction of nonlinear waves in plasmas are reviewed. Their relevance to plasma-based beat wave accelerators, short pulse laser and particle beam wake-field accelerators, plasma lenses, laser fusion and ionospheric modification experiments is discussed. Some introductory lectures present the general physics of nonlinear plasma waves including the saturation mechanisms and wave breaking conditions for both non-relativistic and relativistic nonlinearities. Three wave and four wave processes which include stimulated Raman, Brillouin and Compton scattering, modulational instabilities, self-focusing and collapse of the waves are discussed, emphasizing the important effects due to the relativistic electron mass variation and ponderomotive force. Detailed numerical studies of the interaction of high frequency plasma waves with low frequency density fluctuations described by the Zakharov equations show the localization of the high frequency field in density cavities and their burn-out resulting in very strong turbulence. Remarkable agreement between the simulations and ionospheric modification experiments have been demonstrated. The articles presented also attempted to correlate the theories of parametric instabilities with experimental observations. The properties of plasma lenses used for focusing of high energy particle beams is also presented as part of the uses of the nonlinear plasmas. Self-organisation of plasmas resulting in coherent nonlinear structures and particle diffusion processes are reported. On the experimental side the nonlinear optics of plasmas as a new area of research has been reviewed. This is becoming an important area for research since it treats the plasma from the outset as a nonlinear medium. Experimental observations of phase conjugation of electromagnetic signals demonstrate once again the importance of the nonlinearities inherent in the interaction of large amplitude waves with plasmas. Finally the importance of turbulence in space plasmas is emphasized in a discussion of the auroral phenomenon, presenting the plasma physicists point of view on this topic. The workshop, attended by scientists from all over the world, stimulated a great deal of lively discussions about the theoretical foundations, experimental observations and interpretations together with computer simulation results on the physics of nonlinear plasma wave phenomena. The workshop was made possible by the kind support of Professors A Salam, L Bertocchi and M Hassan. We are grateful to them for giving us the opportunity to organize the workshop within the activities of the Spring College on Plasma Physics. Thanks are also due to the ICTP and the European Economic Community (EEC) for providing partial financial support. Finally, our most cordial thanks are extended to the invited speakers for coming to Trieste delivering excellent talks and enhancing the activity of the Spring College.

The use of laser-induced shock wave plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdulmadjid, Syahrun Nur, E-mail: syahrun-madjid@yahoo.com; Lahna, Kurnia, E-mail: kurnialahna@gmail.com; Desiyana, Lydia Septa, E-mail: lydia-septa@yahoo.com

2016-03-11

An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma induced by Nd-YAG laser at a low pressure of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-Induced Shock Wave Plasma Spectroscopy (LISPS), the shock wave has a significant role in inducing atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablatedmore » atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-induced plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.« less

Statistical analysis of dispersion relations in turbulent solar wind fluctuations using Cluster data

NASA Astrophysics Data System (ADS)

Perschke, C.; Narita, Y.

2012-12-01

Multi-spacecraft measurements enable us to resolve three-dimensional spatial structures without assuming Taylor's frozen-in-flow hypothesis. This is very useful to study frequency-wave vector diagram in solar wind turbulence through direct determination of three-dimensional wave vectors. The existence and evolution of dispersion relation and its role in fully-developed plasma turbulence have been drawing attention of physicists, in particular, if solar wind turbulence represents kinetic Alfvén or whistler mode as the carrier of spectral energy among different scales through wave-wave interactions. We investigate solar wind intervals of Cluster data for various flow velocities with a high-resolution wave vector analysis method, Multi-point Signal Resonator technique, at the tetrahedral separation about 100 km. Magnetic field data and ion data are used to determine the frequency- wave vector diagrams in the co-moving frame of the solar wind. We find primarily perpendicular wave vectors in solar wind turbulence which justify the earlier discussions about kinetic Alfvén or whistler wave. The frequency- wave vector diagrams confirm (a) wave vector anisotropy and (b) scattering in frequencies.

Revealing plasma oscillation in THz spectrum from laser plasma of molecular jet.

PubMed

Li, Na; Bai, Ya; Miao, Tianshi; Liu, Peng; Li, Ruxin; Xu, Zhizhan

2016-10-03

Contribution of plasma oscillation to the broadband terahertz (THz) emission is revealed by interacting two-color (ω/2ω) laser pulses with a supersonic jet of nitrogen molecules. Temporal and spectral shifts of THz waves are observed as the plasma density varies. The former owes to the changing refractive index of the THz waves, and the latter correlates to the varying plasma frequency. Simulation of considering photocurrents, plasma oscillation and decaying plasma density explains the broadband THz spectrum and the varying THz spectrum. Plasma oscillation only contributes to THz waves at low plasma density owing to negligible plasma absorption. At the longer medium or higher density, the combining effects of plasma oscillation and absorption results in the observed low-frequency broadband THz spectra.

Continuous Wave Ring-Down Spectroscopy for Velocity Distribution Measurements in Plasma

NASA Astrophysics Data System (ADS)

McCarren, Dustin W.

Cavity Ring-Down Spectroscopy CRDS is a proven, ultra-sensitive, cavity enhanced absorption spectroscopy technique. When combined with a continuous wavelength (CW) diode laser that has a sufficiently narrow line width, the Doppler broadened absorption line, i.e., the velocity distribution functions (VDFs) of the absorbing species, can be measured. Measurements of VDFs can be made using established techniques such as laser induced fluorescence (LIF). However, LIF suffers from the requirement that the initial state of the LIF sequence have a substantial density and that the excitation scheme fluoresces at an easily detectable wavelength. This usually limits LIF to ions and atoms with large metastable state densities for the given plasma conditions. CW-CRDS is considerably more sensitive than LIF and can potentially be applied to much lower density populations of ion and atom states. Also, as a direct absorption technique, CW-CRDS measurements only need to be concerned with the species' absorption wavelength and provide an absolute measure of the line integrated initial state density. Presented in this work are measurements of argon ion and neutral VDFs in a helicon plasma using CW-CRDS and LIF.

Nonlinear wave interaction in a plasma column

NASA Technical Reports Server (NTRS)

Larsen, J.

1972-01-01

Two particular cases of nonlinear wave interaction in a plasma column were investigated. The frequencies of the waves were on the order of magnitude of the electron plasma frequency, and ion motion was neglected. The nonlinear coupling of slow waves on a plasma column was studied by means of cold plasma theory, and the case of a plasma column surrounded by an infinite dielectric in the absence of a magnetic field was also examined. Nonlinear scattering from a plasma column in an electromagnetic field having it's magnetic field parallel to the axis of the column was investigated. Some experimental results on mode conversion in the presence of loss are presented along with some observations of nonlinear scattering, The effect of the earth's magnetic field and of discharge symmetry on the radiation pattern are discussed.

Intensity moments by path integral techniques for wave propagation through random media, with application to sound in the ocean

NASA Technical Reports Server (NTRS)

Bernstein, D. R.; Dashen, R.; Flatte, S. M.

1983-01-01

A theory is developed which describes intensity moments for wave propagation through random media. It is shown using the path integral technique that these moments are significantly different from those of a Rayleigh distribution in certain asymptotic regions. The path integral approach is extended to inhomogeneous, anisotropic media possessing a strong deterministic velocity profile. The behavior of the corrections to Rayleigh statistics is examined, and it is shown that the important characteristics can be attributed to a local micropath focusing function. The correction factor gamma is a micropath focusing parameter defined in terms of medium fluctuations. The value of gamma is calculated for three ocean acoustic experiments, using internal waves as the medium fluctuations. It is found that all three experiments show excellent agreement as to the relative values of the intensity moments. The full curved ray is found to yield results that are significantly different from the straight-line approximations. It is noted that these methods are applicable to a variety of experimental situations, including atmospheric optics and radio waves through plasmas.

BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas

NASA Astrophysics Data System (ADS)

Porkolab, Miklos

1998-11-01

The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is somewhat more detailed in certain topics than, and complementary in many fusion research relevant areas to, Stix's book. (I am restricting these comments to the homogeneous plasma theory only, since the author promises a second volume on wave propagation in inhomogeneous plasmas.) This book is also much more of a theorist's approach to waves in plasmas, with the aim of developing the subject within the logical framework of kinetic theory. This may indeed be pleasing to the expert and to the specialist, but may be too difficult to the graduate student as an `introduction' to the subject (which the author explicitly states in the Preface). On the other hand, it may be entirely appropriate for a second course on plasma waves, after the student has mastered fluid theory and an introductory kinetic treatment of waves in a hot magnetized `Vlasov' plasma. For teaching purposes, my personal preference is to review the cold plasma wave treatment using the unified Stix formalism and notation (which the author wisely adopts in the present book, but only in Chapter 5). Such an approach allows one to deal with CMA diagrams early on, as well as to provide a framework to discuss electromagnetic wave propagation and accessibility in inhomogeneous plasmas (for which the cold plasma wave treatment is perfectly adequate). Such an approach does lack some of the rigour, however, that the author achieves with the present approach. As the author correctly shows, the fluid theory treatment of waves follows logically from kinetic theory in the cold plasma limit. I only question the pedagogical value of this approach. Otherwise, I welcome this addition to the literature, for it gives the teacher of the subject a valuable reference where the inquisitive student will be able to read up on and satisfy himself about the practicality and reliability of the Vlasov theory in a hot magnetized and collisionless plasma. The book has excellent treatments of several new topics not included in previous textbooks, for example, the relativistic theory of plasma wave propagation, so important in electron cyclotron heating of magnetically confined fusion plasmas, a discussion of current drive theory and there is a welcome introduction to parametric instabilities in the final chapter. There are some things that make the readability of the book somewhat difficult. In the early parts, certain advanced concepts are introduced without much motivation or explanation, although the author is trying to be helpful by providing a list of relevant references at the end of each chapter. Here the teacher's role will be critical. Again, a certain amount of previous knowledge of the subject would prove to be invaluable to the student. The main content of the book is included in 11 chapters. Use is made of CGS Gaussian units, a favourite of plasma theorists. As the author states, these are still widely used in advanced plasma theory, and the student is well advised to become familiar with this system of units (as well as the SI system for applications). To help the reader in the Introduction, the author defines various expressions often used in plasma physics in practical units (frequencies in hertz, lengths in centimetres, temperatures in kiloelectronvolts and magnetic fields in teslas). Chapter 2 is entitled `Plasma Electrodynamics' and it introduces the Maxwell-Vlasov set of equations, as well as the important fundamentals of wave propagation, such as polarization, dispersion and the dielectric tensor, and energy relations. In Chapter 3, `Elementary Plasma Kinetic Theory', the author derives the Vlasov equation and the Fokker-Planck equation from the BBGKY hierarchy. This is a somewhat unusual chapter in a book on plasma waves, but I welcome it since it demonstrates the author's desire to be complete and rigorous in justifying the use of the collisionless Vlasov equation for `high frequency' wave propagation phenomena. Incidentally, it is interesting that while the author derives the Fokker-Planck equation at great length, it is used only to derive the fluid and MHD equations, but not for estimating Coulomb collisional damping of specific waves in later chapters. Chapter 4 gives the derivation of the hot plasma dielectric tensor. There is an extensive and excellent discussion of the relativistic formulation of the dielectric tensor, which is of fundamental importance to practising fusion physicists (for example) involved in ECR heating of high temperature plasmas. Various temperature limits are taken in Chapters 5, 6 and 7, and the author discusses the infinite number of waves in the cold plasma limit (Chapter 5), in the hot plasma limit (Chapter 6) and in the electrostatic limit (Chapter 7). In my opinion, these chapters represent the `meat' of the book. Chapter 7 includes a detailed treatment of electrostatic waves in a hot plasma, including Bernstein waves and their damping at high harmonics. This is a difficult topic, and the extensive treatment presented here is hard to find in other texts. The author also includes a discussion of two stream instabilities here, together with the Nyquist-Penrose criterion for instability. Chapter 8 discusses linear wave-particle interactions, including damping of electromagnetic waves, RF current drive and RF heating. Chapter 9 is called `Collisionless Stochasticity' and institutes an introduction to the subject as well as applications to the heating of ions by high harmonic, lower hybrid waves. Chapter 10 is another key part of the book, on the quasilinear theory of heating and current drive. It deals with the practical aspects of RF heating and current drive in magnetically confined fusion plasmas, and is a `must read' for researchers dealing with RF heating and related transport. Chapter 11 attempts to deal with non-linear effects in the presence of high power RF waves in plasmas. First, the author deals with the difficult subject of mode coupling theory, but, owing to its complexity, the formulation is never reduced to practical applications. Only the `dipole approximation' section can be used to make practical estimates of non-linear effects during RF heating. There are some shortcomings of this book that need to be mentioned here. There are some typographical errors, including spelling errors. The labelling on the figures is often hard to read due to their poor quality and small size. The figures themselves are often too small and are overloaded with curves (e.g., Figs 18.1, 18.2, 21.3, 28.13). The author must have spent a significant effort in producing these curves, and they deserve a better presentation, especially if they are to be used by students. Ease of readability is important for a textbook intended for students and researchers alike. It is hoped that such shortcomings will be improved in future editions, as well as in Volume II, which is to follow. To summarize, this book presents an up to date major contribution to the field of plasma waves and is a `must' on the shelves of active researchers as well as advanced graduate students. Under the guidance of a knowledgeable teacher, the book may be used as a text, with appropriate omissions of certain sections for a one semester course in plasma waves. Alternatively for those who have mastered the fundamentals of wave propagation in plasmas, the book could be used as a basis for an advanced seminar course. I am looking forward with anticipation to Volume II, Waves in Inhomogeneous Plasmas, by Marco Brambilla, one of the eminent plasma wave theorists of our generation.

Plasma waves near the magnetopause

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, R.R.; Haravey, C.C.; Hoppe, M.M.

1982-04-01

Plasma waves associated with the magnetopause, from the magnetosheath to the outer magnetosphere, are examined with an emphasis on high time resolution data and the comparison between measurements by using different antenna systems. An early ISEE crossing of the magnetopause region, including passage through two well-defined flux transfer events, the magentopause current layer, and boundary plasma, is studied in detail. The waves in these regions are compared and contrasted with the waves in the adjoining magnetosheath and outer magnetosphere. Four types of plamsa wave emissions are characteristic of the nominal magnetosheat: (1) a very low frequency continuum, (2) short wavelengthmore » spikes, (3) 'festoon-shaped' emissions below about 2 kHz, and (4) 'lion roars'. The latter two emissions are well correlated with ultra-low frequency magnetic field fluctuations. The dominant plasma wave features during flux transfer events are (1) an intense low-frequency continuum, which includes a substantial electromagnetic component, (2) a dramatic increase in the frequency of occurrence of the spikes, (3) quasi-periodic electron cyclotron harmonics correlated with approx.1-Hz magnetic field fluctuations, and (4) enhanced electron plasma oscillations. The plasma wave characteristics in the current layer and in the boundary layer are quite similar to the features in the flux transfer events. Upon entry into the outer magnetosphere, the plasma wave spectra are dominated by intense electromagnetic chorus bursts and electrosatic (n+1/2)f/sup -//sub g/ emissions. Wavelength determinations made by comparing the various antenna responses and polarization measurements for the different waves are also presented.« less

Variable dual-frequency electrostatic wave launcher for plasma applications.

PubMed

Jorns, Benjamin; Sorenson, Robert; Choueiri, Edgar

2011-12-01

A variable tuning system is presented for launching two electrostatic waves concurrently in a magnetized plasma. The purpose of this system is to satisfy the wave launching requirements for plasma applications where maximal power must be coupled into two carefully tuned electrostatic waves while minimizing erosion to the launching antenna. Two parallel LC traps with fixed inductors and variable capacitors are used to provide an impedance match between a two-wave source and a loop antenna placed outside the plasma. Equivalent circuit analysis is then employed to derive an analytical expression for the normalized, average magnetic flux density produced by the antenna in this system as a function of capacitance and frequency. It is found with this metric that the wave launcher can couple to electrostatic modes at two variable frequencies concurrently while attenuating noise from the source signal at undesired frequencies. An example based on an experiment for plasma heating with two electrostatic waves is used to demonstrate a procedure for tailoring the wave launcher to accommodate the frequency range and flux densities of a specific two-wave application. This example is also used to illustrate a method based on averaging over wave frequencies for evaluating the overall efficacy of the system. The wave launcher is shown to be particularly effective for the illustrative example--generating magnetic flux densities in excess of 50% of the ideal case at two variable frequencies concurrently--with a high adaptability to a number of plasma dynamics and heating applications.

Coupling of an acoustic wave to shear motion due to viscous heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Bin; Goree, J.

2016-07-15

Viscous heating due to shear motion in a plasma can result in the excitation of a longitudinal acoustic wave, if the shear motion is modulated in time. The coupling mechanism is a thermal effect: time-dependent shear motion causes viscous heating, which leads to a rarefaction that can couple into a longitudinal wave, such as an acoustic wave. This coupling mechanism is demonstrated in an electrostatic three-dimensional (3D) simulation of a dusty plasma, in which a localized shear flow is initiated as a pulse, resulting in a delayed outward propagation of a longitudinal acoustic wave. This coupling effect can be profoundmore » in plasmas that exhibit localized viscous heating, such as the dusty plasma we simulated using parameters typical of the PK-4 experiment. We expect that a similar phenomenon can occur with other kinds of plasma waves.« less

Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr

The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order.more » It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.« less

KINETIC-J: A computational kernel for solving the linearized Vlasov equation applied to calculations of the kinetic, configuration space plasma current for time harmonic wave electric fields

NASA Astrophysics Data System (ADS)

Green, David L.; Berry, Lee A.; Simpson, Adam B.; Younkin, Timothy R.

2018-04-01

We present the KINETIC-J code, a computational kernel for evaluating the linearized Vlasov equation with application to calculating the kinetic plasma response (current) to an applied time harmonic wave electric field. This code addresses the need for a configuration space evaluation of the plasma current to enable kinetic full-wave solvers for waves in hot plasmas to move beyond the limitations of the traditional Fourier spectral methods. We benchmark the kernel via comparison with the standard k →-space forms of the hot plasma conductivity tensor.

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave

PubMed Central

Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; Boardsen, Scott A.; Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.; Saito, Yoshifumi; Paterson, William R.; Fuselier, Stephen A.; Ergun, Robert E.; Strangeway, Robert J.; Russell, Christopher T.; Giles, Barbara L.; Pollock, Craig J.; Torbert, Roy B.; Burch, James L.

2017-01-01

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations. PMID:28361881

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave.

PubMed

Gershman, Daniel J; F-Viñas, Adolfo; Dorelli, John C; Boardsen, Scott A; Avanov, Levon A; Bellan, Paul M; Schwartz, Steven J; Lavraud, Benoit; Coffey, Victoria N; Chandler, Michael O; Saito, Yoshifumi; Paterson, William R; Fuselier, Stephen A; Ergun, Robert E; Strangeway, Robert J; Russell, Christopher T; Giles, Barbara L; Pollock, Craig J; Torbert, Roy B; Burch, James L

2017-03-31

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.

Electron plasma oscillations in the Venus foreshock

NASA Technical Reports Server (NTRS)

Crawford, G. K.; Strangeway, R. J.; Russell, C. T.

1990-01-01

Plasma waves are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These wave signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. The electron foreshock boundary is clearly evident in the data as a sharp onset in wave activity and a peak in intensity. Wave intensity is seen to drop rapidly with increasing penetration into the foreshock. The peak wave electric field strength at the electron foreshock boundary is found to be similar to terrestrial observations. A normalized wave spectrum was constructed using measurements of the electron plasma frequency and the spectrum was found to be centered about this value. These results, along with polarization studies showing the wave electric field to be field aligned, are consistent with the interpretation of the waves as electron plasma oscillations.

Wave-Particle Energy Exchange Directly Observed in a Kinetic Alfven-Branch Wave

NASA Technical Reports Server (NTRS)

Gershman, Daniel J.; F-Vinas, Adolfo; Dorelli, John C.; Boardsen, Scott A. (Inventor); Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.;

Overview of Spontaneous Frequency Chirping in Confined Plasmas

NASA Astrophysics Data System (ADS)

Berk, Herbert

2012-10-01

Spontaneous rapid frequency chirping is now a commonly observed phenomenon in plasmas with an energetic particle component. These particles typically induce so called weak instabilities, where they excite background waves that the plasma can support such as shear Alfven waves. The explanation for this phenomenon attributes the frequency chirping to the formation of phase space structures in the form of holes and clumps. Normally a saturated mode, in the presence of background dissipation, would be expected decay after saturation as the background plasma absorbs the energy of the excited wave. However the phase space structures take an alternate route, and move to a regions of phase space that are lower energy states of the energetic particle distribution. Through the wave-resonant particle interaction, this movement is locked to the frequency observed by the wave. This phenomenon implies that alternate mechanisms for plasma relaxation need to be considered for plasma states new marginal stability. It is also possible that these chirping mechanisms can be used to advantage to externally control states of plasma.

Hydrodynamic Model of Spatio-Temporal Evolution of Two-Plasmon Decay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dimitrijevic, D. R.; Maluckov, A. A.

A hydrodynamic model of two-plasmon decay in a homogeneous plasma slab near the quarter-critical density is constructed in order to gain better insight into the spatio-temporal evolution of the daughter electron plasma waves in plasma in the course of the instability. The influence of laser and plasma parameters on the evolution of the amplitudes of the participating waves is discussed. The secondary coupling of two daughter electron plasma waves with an ion-acoustic wave is assumed to be the principal mechanism of saturation of the instability. The impact of the inherently nonresonant nature of this secondary coupling on the development ofmore » TPD is investigated and it is shown to significantly influence the electron plasma wave dynamics. Its inclusion leads to nonuniformity of the spatial profile of the instability and causes the burst-like pattern of the instability development, which should result in the burst-like hot-electron production in homogeneous plasma.« less

Electromagnetic fluctuation spectra of collective oscillations in magnetized Maxwellian equal mass plasmas for low-frequency waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vafin, S.; Schlickeiser, R.; Yoon, P. H.

Recently, the general electromagnetic fluctuation theory for magnetized plasmas has been used to study the steady-state fluctuation spectra and the total intensity of low-frequency collective weakly damped modes for parallel wave vectors in Maxwellian plasmas. Now, we address the same question with respect to an arbitrary direction of the wave-vector. Here, we analyze this problem for equal mass plasmas. These plasmas are a very good tool to study various plasma phenomena, as they considerably facilitate the theoretical consideration and at the same time provide with their clear physical picture. Finally, we compare our results in the limiting case of parallelmore » wave vectors with the previous study.« less

Surface wave and linear operating mode of a plasma antenna

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogachev, N. N., E-mail: bgniknik@yandex.ru; Bogdankevich, I. L.; Gusein-zade, N. G.

The relation between the propagation conditions of a surface electromagnetic wave along a finiteradius plasma cylinder and the linear operating mode of a plasma antenna is investigated. The solution to the dispersion relation for a surface wave propagating along a finite-radius plasma cylinder is analyzed for weakly and strongly collisional plasmas. Computer simulations of an asymmetrical plasma dipole antenna are performed using the KARAT code, wherein the dielectric properties of plasma are described in terms of the Drude model. The plasma parameters corresponding to the linear operating mode of a plasma antenna are determined. It is demonstrated that the characteristicsmore » of the plasma antenna in this mode are close to those of an analogous metal antenna.« less

Propagation characteristics of electromagnetic waves in dusty plasma with full ionization

NASA Astrophysics Data System (ADS)

Dan, Li; Guo, Li-Xin; Li, Jiang-Ting

2018-01-01

This study investigates the propagation characteristics of electromagnetic (EM) waves in fully ionized dusty plasmas. The propagation characteristics of fully ionized plasma with and without dust under the Fokker-Planck-Landau (FPL) and Bhatnagar-Gross-Krook (BGK) models are compared to those of weakly ionized plasmas by using the propagation matrix method. It is shown that the FPL model is suitable for the analysis of the propagation characteristics of weakly collisional and fully ionized dusty plasmas, as is the BGK model. The influence of varying the dust parameters on the propagation properties of EM waves in the fully ionized dusty plasma was analyzed using the FPL model. The simulation results indicated that the densities and average radii of dust grains influence the reflection and transmission coefficients of fully ionized dusty plasma slabs. These results may be utilized to analyze the effects of interaction between EM waves and dusty plasmas, such as those associated with hypersonic vehicles.

geometric optics and WKB method for electromagnetic wave propagation in an inhomogeneous plasma near cutoff

DOE Office of Scientific and Technical Information (OSTI.GOV)

Light, Max Eugene

This report outlines the theory underlying electromagnetic (EM) wave propagation in an unmagnetized, inhomogeneous plasma. The inhomogeneity is given by a spatially nonuniform plasma electron density n e(r), which will modify the wave propagation in the direction of the gradient rn e(r).

Self-injection of electrons in a laser-wakefield accelerator by using longitudinal density ripple

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahiya, Deepak; Sharma, A. K.; Sajal, Vivek

By introducing a longitudinal density ripple (periodic modulation in background plasma density), we demonstrate self-injection of electrons in a laser-wakefield accelerator. The wakefield driven plasma wave, in presence of density ripple excites two side band waves of same frequency but different wave numbers. One of these side bands, having smaller phase velocity compared to wakefield driven plasma wave, preaccelerates the background plasma electrons. Significant number of these preaccelerated electrons get trapped in the laser-wakefield and further accelerated to higher energies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreev, Pavel A., E-mail: andreevpa@physics.msu.ru; Kuz’menkov, L.S., E-mail: lsk@phys.msu.ru

We consider quantum plasmas of electrons and motionless ions. We describe separate evolution of spin-up and spin-down electrons. We present corresponding set of quantum hydrodynamic equations. We assume that plasmas are placed in an uniform external magnetic field. We account different occupation of spin-up and spin-down quantum states in equilibrium degenerate plasmas. This effect is included via equations of state for pressure of each species of electrons. We study oblique propagation of longitudinal waves. We show that instead of two well-known waves (the Langmuir wave and the Trivelpiece–Gould wave), plasmas reveal four wave solutions. New solutions exist due to bothmore » the separate consideration of spin-up and spin-down electrons and different occupation of spin-up and spin-down quantum states in equilibrium state of degenerate plasmas.« less

Generation of waves in the Venus mantle by the ion acoustic beam instability

NASA Technical Reports Server (NTRS)

Huba, J. D.

1993-01-01

The ion acoustic beam instability is suggested as a mechanism to produce wave turbulence observed in the Venus mantle at frequencies 100 Hz and 730 Hz. The plasma is assumed to consist of a stationary cold O(+) ion plasma and a flowing, shocked solar wind plasma. The O(+) ions appear as a beam relative to the flowing ionosheath plasma which provides the free energy to drive the instability. The plasma is driven unstable by inverse electron Landau damping of an ion acoustic wave associated with the cold ionospheric O(+) ions. The instability can directly generate the observed 100 Hz waves in the Venus mantle as well as the observed 730 Hz waves through the Doppler shift of the frequency caused by the satellite motion.

Helicon and Trivelpiece-Gould modes in uniform unbounded plasmas

NASA Astrophysics Data System (ADS)

Stenzel, R. L.; Urrutia, J. M.

2016-10-01

Helicon modes are whistler modes with angular orbital momentum caused by phase rotation in addition to the axial phase propagation. Although these modes have been associated with whistler eigenmodes in bounded plasma columns, they do exist in unbounded plasmas. Experiments in a large laboratory plasma show the wave excitation with phased antenna arrays, the wave field topology and the propagation of helicons. Low frequency whistlers can have two modes with different wavelengths at a given frequency, called helicons and Trivelpiece-Gould modes. The latter are whistler modes near the oblique cyclotron resonance. The oblique propagation is due to short radial wavelengths near the boundary. In unbounded plasmas, the oblique propagation arises from short azimuthal wavelengths. This has been observed in high-mode number helicons (e.g., m = 8). It creates wave absorption in the center of the helicon mode. The strong absorption of the wave can heat electrons and create perpendicular wave-particle interactions. These results may be of interest in space plasmas for scattering of energetic electrons and in helicon plasma sources for plasma processing and thruster applications. Work supported by NSF/DOE.

Using neutral beams as a light ion beam probe (invited)

DOE PAGES

Chen, Xi; Heidbrink, William W.; Van Zeeland, Michael A.; ...

2014-08-05

By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of 1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge, and 2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fieldsmore » appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g. Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally-imposed 3D fields, e.g. magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. Additionally, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.« less

Using neutral beams as a light ion beam probe (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xi, E-mail: chenxi@fusion.gat.com; Heidbrink, W. W.; Van Zeeland, M. A.

By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of (1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge and (2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fieldsmore » appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g., Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally imposed 3D fields, e.g., magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. In addition, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.« less

Using neutral beams as a light ion beam probe (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xi; Heidbrink, William W.; Van Zeeland, Michael A.

By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of 1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge, and 2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fieldsmore » appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g. Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally-imposed 3D fields, e.g. magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. Additionally, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.« less

Space plasma simulations; Proceedings of the Second International School for Space Simulations, Kapaa, HI, February 4-15, 1985. Parts 1 & 2

NASA Technical Reports Server (NTRS)

Ashour-Abdalla, M. (Editor); Dutton, D. A. (Editor)

1985-01-01

Space plasma simulations, observations, and theories are discussed. Papers are presented on the capabilities of various types of simulation codes and simulation models. Consideration is given to plasma waves in the earth's magnetotail, outer planet magnetosphere, geospace, and the auroral and polar cap regions. Topics discussed include space plasma turbulent dissipation, the kinetics of plasma waves, wave-particle interactions, whistler mode propagation, global energy regulation, and auroral arc formation.

Using phase locking for improving frequency stability and tunability of THz-band gyrotrons

NASA Astrophysics Data System (ADS)

Adilova, Asel B.; Gerasimova, Svetlana A.; Melnikova, Maria M.; Tyshkun, Alexandra V.; Rozhnev, Andrey G.; Ryskin, Nikita M.

2018-04-01

Medium-power (10-100 W) THz-band gyrotrons operating in a continuous-wave (CW) mode are of great importance for many applications such as NMR spectroscopy with dynamic nuclear polarization (DNP/NMR), plasma diagnostics, nondestructive inspection, stand-off detection of radioactive materials, biomedical applications, etc. For all these applications, high frequency stability and tunability within 1-2 GHz frequency range is typically required. Apart from different existing techniques for frequency stabilization, phase locking has recently attracted strong interest. In this paper, we present the results of theoretical analysis and numerical simulation for several phase locking techniques: (a) phase locking by injection of the external driving signal; (b) mutual phase locking of two coupled gyrotrons; and (c) selfinjection locking by a wave reflected from the remote load.

A Study on the Transient Behavior of Pulse Modulated Dual-Frequency Capacitive Discharges based on Circuit Analysis

NASA Astrophysics Data System (ADS)

Na, Byungkeun; Bae, Inshik; Park, Gi Jung; Chang, Hong-Young

2016-09-01

Multi-frequency capacitively coupled plasma (CCP) has been studied to independently control the ion energy and the ion flux; pulsing technique is used to reduce the electron temperature and finally the charging effects. The use of these techniques is a key to high aspect ratio contact (HARC) etching in the recent semiconductor processing. In this study, the characteristics of pulsed dual frequency (DF) CCP is investigated. Two separate powers of 3 MHz and 40 MHz are delivered to the powered electrode of an asymmetric CCP, and each frequency is modulated by an external 1 kHz pulse. Due to the complexity of the RF compensation in DF CCP, the characteristics of the plasma and the sheath are analyzed by high speed impedance measurement. The transient behavior of pulse modulated DF CCP is analyzed based on the result of continuous wave (CW) DF CCP. The optimized experimental condition for high ion energy will be presented. The difference between electronegative oxygen plasma and electropositive argon plasma is discussed as well.

Spectral Calculation of ICRF Wave Propagation and Heating in 2-D Using Massively Parallel Computers

NASA Astrophysics Data System (ADS)

Jaeger, E. F.; D'Azevedo, E.; Berry, L. A.; Carter, M. D.; Batchelor, D. B.

2000-10-01

Spectral calculations of ICRF wave propagation in plasmas have the natural advantage that they require no assumption regarding the smallness of the ion Larmor radius ρ relative to wavelength λ. Results are therefore applicable to all orders in k_bot ρ where k_bot = 2π/λ. But because all modes in the spectral representation are coupled, the solution requires inversion of a large dense matrix. In contrast, finite difference algorithms involve only matrices that are sparse and banded. Thus, spectral calculations of wave propagation and heating in tokamak plasmas have so far been limited to 1-D. In this paper, we extend the spectral method to 2-D by taking advantage of new matrix inversion techniques that utilize massively parallel computers. By spreading the dense matrix over 576 processors on the ORNL IBM RS/6000 SP supercomputer, we are able to solve up to 120,000 coupled complex equations requiring 230 GBytes of memory and achieving over 500 Gflops/sec. Initial results for ASDEX and NSTX will be presented using up to 200 modes in both the radial and vertical dimensions.

Landau damping of the dust-acoustic surface waves in a Lorentzian dusty plasma slab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590

2016-01-15

Landau damping of a dust-acoustic surface wave propagating at the interfaces of generalized Lorentzian dusty plasma slab bounded by a vacuum is kinetically derived as the surface wave displays the symmetric and the anti-symmetric mode in a plasma slab. In the limiting case of small scaled wave number, we have found that Landau damping is enhanced as the slab thickness is increased. In particular, the damping of anti-symmetric mode is much stronger for a Lorentzian plasma than for a Maxwellian plasma. We have also found that the damping is more affected by superthermal particles in a Lorentzian plasma than bymore » a Maxwellian plasma for both of the symmetric and the anti-symmetric cases. The variations of Landau damping with various parameters are also discussed.« less

Sensitivity of wave propagation in the LHRF to initial poloidal position in finite-aspect-ratio toroidal plasmas

NASA Astrophysics Data System (ADS)

Larson, J. J.; Pinsker, R. I.; Bonoli, P. T.; Porkolab, M.

2017-10-01

The important effect of varying the initial poloidal wave-launching location to the core accessibility of lower hybrid slow waves in a torus of finite aspect ratio has been understood for many years. Since the qualitative properties of the wave propagation of the other branch in this regime, known as the `whistler', `helicon' or simply the `fast wave', are similar in some ways to those of the slow wave, we expect a dependence on launch position for this wave also. We study this problem for both slow and fast waves, first with simplified analytic models and then using the ray-tracing code GENRAY for realistic plasma equilibria. We assess the prospects of inside, top, bottom or conventional outside launch of waves on each of the two branches. Although the slow wave has been the focus of research for LHRF heating and current drive in the past, the fast wave will play a major role in burning plasmas beyond ITER where Te(0) = 10-20 keV. The stronger electron Landau damping of the slow wave will restrict the power deposition to the outer third of the plasma, while the fast wave's weaker damping allows the wave to penetrate to the hot plasma core before depositing its power. Work supported in part by US DoE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698 and DE-FG02-91-ER54109.

The Radio & Plasma Wave Investigation (RPWI) for JUICE - From Jupiter's Magnetosphere, through the Ice Shell, and into the Ocean of Ganymede

NASA Astrophysics Data System (ADS)

Bergman, J. E. S.; Wahlund, J.-E.; Witasse, O.; Cripps, V.

2017-09-01

The Radio & Plasma Wave Investigation (RPWI) on board the JUICE mission to Jupiter and its icy moons will enhance our understanding of magnetospheric and ionospheric physics processes in the Jupiter system, with emphasis on its icy moon Ganymede. By using innovative measurement techniques, such as passive ground penetrating radar, RPWI will also investigate the ice shell and try to measure its thickness. RPWI will as well help to detect and characterise the subsurface ocean of Ganymede. Thereby, RPWI will contribute to many high level science objectives, not foreseen when the instrument was proposed and selected for flight by ESA. The close collaboration with the two other in situ payload teams (JMAG and PEP), on ground and on board the JUICE spacecraft, will further enhance the value of our combined data sets.

Ionosphere-magnetosphere studies using ground based VLF radio propagation technique: an Indian example

NASA Astrophysics Data System (ADS)

Chakravarty, Subhas

Since IGY period (1957-58), natural and artificially produced Very Low Frequency (VLF) elec-tromagnetic radiations are being recorded at large number of ground stations all over the world and on-board satellites to study various radio wave-thermal/energetic plasma interactive pro-cesses related to earth's ionosphere-plasmasphere-magnetosphere environment. The terrestrial propagation of these VLF radio waves are primarily enabled through the earth ionosphere wave guide (EIWG) mode to long horizontal distances around the globe and ducted along the ge-omagnetic field lines into the conjugate hemisphere through the plasmasphere-magnetosphere regions. The time frequency spectra of the received signals indicate presence of dispersion (wave/group velocities changing with frequency) and various cut-off frequencies based on the width of the EIWG, electron gyro and plasma frequencies etc., providing several types of received signals like whistlers, chorus, tweeks, hiss and hisslers which can be heard on loud-speakers/earphones with distinguishing audio structures. While the VLF technique has been a very effective tool for studying middle and high latitude phenomena, the importance of the similar and anomalous observations over the Indian low latitude stations provide potentially new challenges for their scientific interpretation and modelling. The ducted and non-ducted magnetospheric propagation, pro-longitudinal (PL) mode, low latitude TRIMPI/TLE (Tran-sient Luminous Emissions) or other effects of wave-particle/wave-wave interactions, effects due to ionospheric irregularities and electric fields, full wave solutions to D-region ionisation per-turbations due to solar and stellar energetic X-and γ ray emissions during normal and flaring conditions are a few problems which have been addressed in these low latitude studies over India. Since the conjugate points of Indian stations lie over the Indian oceanic region, the VLF propagation effects would be relatively free from sferics at least in some seasons providing a noise free environment for observing rare and new phenomena requiring better SNR to detect such changes, The VLF signals from the active seismic zones or other electro-geological sources would require high sensitivities of the system and suitable network of transmitting and receiv-ing stations designed for targeted data and applications. Some new results over Indian and other regions show evidences of earthquake related seismo-geological VLF emissions with the potential of being used as a prognostic tool, change in ozone and ion production in the night time middle atmosphere due to transit of stellar x-ray/γ ray sources. Results obtained on whistlers and related studies from a number of Indian stations covering geomagnetic latitude range between 13-24 N will be mentioned and reviewed in the background of theoretical understanding of the lightning return stroke signal elements, VLF propagation through cold plasma, ionospheric wave guide mode, electron precipitation due to cyclotron resonance and production of atomic oxygen O (3 P) and ionisation in the mesosphere due to solar/stellar UV/X/γrays. Use of future VLF techniques in terms of improving ground based observations, critical analysis of available satellite data in the context and real time moni-toring/modelling of earth's geosphere and space weather conditions will be considered for a possible programme of a developing country.

Electron-acoustic solitary waves in dense quantum electron-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misra, A. P.; Shukla, P. K.; Bhowmik, C.

2007-08-15

A quantum hydrodynamic (QHD) model is used to investigate the propagation characteristics of nonlinear electron-acoustic solitary waves (EASWs) in a dense quantum plasma whose constituents are two groups of electrons: one inertial cold electrons and other inertialess hot electrons, and the stationary ions which form the neutralizing background. By using the standard reductive perturbation technique, a Kadomtsev-Petviashvili (KP) equation, which governs the dynamics of EASWs, is derived in both spherical and cylindrical geometry. The effects of cold electrons and the density correlations due to quantum fluctuations on the profiles of the amplitudes and widths of the solitary structures are examinedmore » numerically. The nondimensional parameter {delta}=n{sub c0}/n{sub h0}, which is the equilibrium density ratio of the cold to hot electron component, is shown to play a vital role in the formation of both bright and dark solitons. It is also found that the angular dependence of the physical quantities and the presence of cold electrons in a quantum plasma lead to the coexistence of some new interesting novel solitary structures quite distinctive from the classical ones.« less

Initial Simulations of RF Waves in Hot Plasmas Using the FullWave Code

NASA Astrophysics Data System (ADS)

Zhao, Liangji; Svidzinski, Vladimir; Spencer, Andrew; Kim, Jin-Soo

2017-10-01

FullWave is a simulation tool that models RF fields in hot inhomogeneous magnetized plasmas. The wave equations with linearized hot plasma dielectric response are solved in configuration space on adaptive cloud of computational points. The nonlocal hot plasma dielectric response is formulated by calculating the plasma conductivity kernel based on the solution of the linearized Vlasov equation in inhomogeneous magnetic field. In an rf field, the hot plasma dielectric response is limited to the distance of a few particles' Larmor radii, near the magnetic field line passing through the test point. The localization of the hot plasma dielectric response results in a sparse matrix of the problem thus significantly reduces the size of the problem and makes the simulations faster. We will present the initial results of modeling of rf waves using the Fullwave code, including calculation of nonlocal conductivity kernel in 2D Tokamak geometry; the interpolation of conductivity kernel from test points to adaptive cloud of computational points; and the results of self-consistent simulations of 2D rf fields using calculated hot plasma conductivity kernel in a tokamak plasma with reduced parameters. Work supported by the US DOE ``SBIR program.

Low Frequency Turbulence as the Source of High Frequency Waves in Multi-Component Space Plasmas

NASA Technical Reports Server (NTRS)

Khazanov, George V.; Krivorutsky, Emmanuel N.; Uritsky, Vadim M.

2011-01-01

Space plasmas support a wide variety of waves, and wave-particle interactions as well as wavewave interactions are of crucial importance to magnetospheric and ionospheric plasma behavior. High frequency wave turbulence generation by the low frequency (LF) turbulence is restricted by two interconnected requirements: the turbulence should be strong enough and/or the coherent wave trains should have the appropriate length. These requirements are strongly relaxed in the multi-component plasmas, due to the heavy ions large drift velocity in the field of LF wave. The excitation of lower hybrid waves (LHWs), in particular, is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves, in particular those associated with LF turbulence, may generate LHW s in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We also argue that the described scenario can playa vital role in various parts of the outer magnetosphere featuring strong LF turbulence accompanied by LHW activity. Using the data from THEMIS spacecraft, we validate the conditions for such cross-scale coupling in the near-Earth "flow-braking" magnetotail region during the passage of sharp injection/dipolarization fronts, as well as in the turbulent outflow region of the midtail reconnection site.

Plasma Metamaterials for Arbitrary Complex-Amplitude Wave Filters

DTIC Science & Technology

2013-09-10

plasmas as reflectors , 4 absorbers, 4,5 and antennae 6 of electromagnetic waves. In contrast with the other materials in these devices, parameters...are controlled using launching antenna and high-power wave sources. One of the fundamental facts we have learned in microwave plasmas is that...metamaterials.” 29 In this report, we demonstrate the functional composites of plasmas and metamaterials, and the focusing point is verification of

Calculations of Alfven Wave Driving Forces, Plasma Flow and Current Drive in Tokamak Plasmas

NASA Astrophysics Data System (ADS)

Elfimov, Artur; Galvao, Ricardo; Amarante-Segundo, Gesil; Nascimento, Ivan

2000-10-01

A general form of time-averaged poloidal ponderomotive forces induced by fast and kinetic Alfvin waves by direct numerical calculations and in geometric optics approximation are analyzed on the basis of the collisionless two fluid (ions and electrons) magneto-hydrodynamics equation. Analytical approximations are used to clarify the effect of Larmour radius on radio-frequency (RF) ponderomotive forces and on poloidal flows induced by them in tokamak plasmas.The RF ponderomotive force is expressed as a sum of a gradient part and of a wave momentum transfer force, which is proportional to wave dissipation. The gradient electromagnetic stress force is combined with fluid dynamic (Reynolds) stress force. It is shown that accounting only Reynolds stress term can overestimate the plasma flow and it is found that the finite ion Larmor radius effect play fundamental role in ponderomotive forces that can drive a poloidal flow, which is larger than a flow driven by a wave momentum transfer force. Finally, balancing the RF forces by the electron-ion friction and viscous force the current and plasma flows driven by ponderomotive forces are calculated for tokamak plasmas, using a kinetic code [Phys. Plasmas, v.6 (1999) p.2437]. Strongly sheared current and plasma flow waves is found.

Research on Radiation Characteristic of Plasma Antenna through FDTD Method

PubMed Central

Zhou, Jianming; Fang, Jingjing; Lu, Qiuyuan; Liu, Fan

2014-01-01

The radiation characteristic of plasma antenna is investigated by using the finite-difference time-domain (FDTD) approach in this paper. Through using FDTD method, we study the propagation of electromagnetic wave in free space in stretched coordinate. And the iterative equations of Maxwell equation are derived. In order to validate the correctness of this method, we simulate the process of electromagnetic wave propagating in free space. Results show that electromagnetic wave spreads out around the signal source and can be absorbed by the perfectly matched layer (PML). Otherwise, we study the propagation of electromagnetic wave in plasma by using the Boltzmann-Maxwell theory. In order to verify this theory, the whole process of electromagnetic wave propagating in plasma under one-dimension case is simulated. Results show that Boltzmann-Maxwell theory can be used to explain the phenomenon of electromagnetic wave propagating in plasma. Finally, the two-dimensional simulation model of plasma antenna is established under the cylindrical coordinate. And the near-field and far-field radiation pattern of plasma antenna are obtained. The experiments show that the variation of electron density can introduce the change of radiation characteristic. PMID:25114961

Iterative Methods to Solve Linear RF Fields in Hot Plasma

NASA Astrophysics Data System (ADS)

Spencer, Joseph; Svidzinski, Vladimir; Evstatiev, Evstati; Galkin, Sergei; Kim, Jin-Soo

2014-10-01

Most magnetic plasma confinement devices use radio frequency (RF) waves for current drive and/or heating. Numerical modeling of RF fields is an important part of performance analysis of such devices and a predictive tool aiding design and development of future devices. Prior attempts at this modeling have mostly used direct solvers to solve the formulated linear equations. Full wave modeling of RF fields in hot plasma with 3D nonuniformities is mostly prohibited, with memory demands of a direct solver placing a significant limitation on spatial resolution. Iterative methods can significantly increase spatial resolution. We explore the feasibility of using iterative methods in 3D full wave modeling. The linear wave equation is formulated using two approaches: for cold plasmas the local cold plasma dielectric tensor is used (resolving resonances by particle collisions), while for hot plasmas the conductivity kernel (which includes a nonlocal dielectric response) is calculated by integrating along test particle orbits. The wave equation is discretized using a finite difference approach. The initial guess is important in iterative methods, and we examine different initial guesses including the solution to the cold plasma wave equation. Work is supported by the U.S. DOE SBIR program.

Self-consistent discharge growing model of helicon plasma

NASA Astrophysics Data System (ADS)

Isayama, Shogo; Hada, Tohru; Shinohara, Shunjiro; Tanikawa, Takao

2015-11-01

Helicon plasma is a high-density and low-temperature plasma generated by the electromagnetic (Helicon) wave excited in the plasma. It is thought to be useful for various applications including electric thrusters. Physics of helicon plasma production involves such fundamental processes as the wave propagation (dispersion relation), collisional and non-collisional wave damping, plasma heating, ionization/recombination of neutral particles, and modification of the dispersion relation by newly ionized plasma. There remain a number of unsolved physical issues such as, how the Helicon and the TG modes influence the plasma density, electron temperature and their spatial profiles. While the Helicon mode is absorbed in the bulk plasma, the TG mode is mostly absorbed near the edge of the plasma. The local power deposition in the helicon plasma is mostly balanced by collisional loss. This local power balance can give rise to the inhomogeneous electron temperature profile that leads to time evolution of density profile and dispersion relation. In our study, we construct a self-consistent model of the discharge evolution that includes the wave excitation, electron heat transfer, and diffusion of charged particles.

Dust-acoustic waves and stability in the permeating dusty plasma. II. Power-law distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong Jingyu; Du Jiulin; Liu Zhipeng

2012-08-15

The dust-acoustic waves and the stability theory for the permeating dusty plasma with power-law distributions are studied by using nonextensive q-statistics. In two limiting physical cases, when the thermal velocity of the flowing dusty plasma is much larger than, and much smaller than the phase velocity of the waves, we derived the dust-acoustic wave frequency, the instability growth rate, and the instability critical flowing velocity. As compared with the formulae obtained in part I [Gong et al., Phys. Plasmas 19, 043704 (2012)], all formulae of the present cases and the resulting plasma characteristics are q-dependent, and the power-law distribution ofmore » each plasma component of the permeating dusty plasma has a different q-parameter and thus has a different nonextensive effect. Further, we make numerical analyses of an example that a cometary plasma tail is passing through the interplanetary space dusty plasma and we show that these power-law distributions have significant effects on the plasma characteristics of this kind of plasma environment.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, S.; Saha, J. K.; Chandra, R.

The Rayleigh-Ritz variational technique with a Hylleraas basis set is being tested for the first time to estimate the structural modifications of a lithium atom embedded in a weakly coupled plasma environment. The Debye-Huckel potential is used to mimic the weakly coupled plasma environment. The wave functions for both the helium-like lithium ion and the lithium atom are expanded in the explicitly correlated Hylleraas type basis set which fully takes care of the electron-electron correlation effect. Due to the continuum lowering under plasma environment, the ionization potential of the system gradually decreases leading to the destabilization of the atom. Themore » excited states destabilize at a lower value of the plasma density. The estimated ionization potential agrees fairly well with the few available theoretical estimates. The variation of one and two particle moments, dielectric susceptibility and magnetic shielding constant, with respect to plasma density is also been discussed in detail.« less

Helicon wave coupling in KSTAR plasmas for off-axis current drive in high electron pressure plasmas

NASA Astrophysics Data System (ADS)

Wang, S. J.; Wi, H. H.; Kim, H. J.; Kim, J.; Jeong, J. H.; Kwak, J. G.

2017-04-01

A helicon wave current drive is proposed as an efficient off-axis current drive in the high electron β plasmas that are expected in fusion reactors. A high frequency helicon wave coupling was analyzed using the surface impedance at a plasma boundary. A slow wave coupling, which may compete with the helicon wave coupling at a frequency of 500 MHz, is estimated to be lower than the fast wave coupling by an order of magnitude in the KSTAR edge plasma density and in practical Faraday shield misalignment with the magnetic pitch. A traveling wave antenna, which is a two port combline antenna, was analyzed using a simplified lumped element model. The results show that the traveling wave antenna provides load resiliency because of its insensitivity to loading resistance, provided that the loading resistance at a radiating element is limited within a practical range. The combline antenna is attractive because it does not require a matching system and exhibits a high selectivity of parallel refractive index. Based on the analysis, a seven element combline antenna was fabricated and installed at an off-mid-plane offset of 30 cm from the mid-plane in KSTAR. The low power RF characteristics measured during several plasma discharges showed no evidence of slow wave coupling. This is consistent with the expectation made through the surface impedance analysis which predicted low slow wave coupling. The wave coupling to the plasma is easily controlled by a radial outer-gap control and gas puffing. No plasma confinement degradation was observed during the radial outer-gap control of up to 3 cm in H-mode discharges. In a ELMy plasmas, only a small reflection peak was observed during a very short portion of the ELM bursting period. If the number of radiating elements is increased for high power operation, then complete load resiliency can be expected. A very large coupling can be problematic for maintaining a parallel refractive index, although this issue can be mitigated by increasing the number of elements.

Stimulated Parametric Decay of Large Amplitude Alfvén waves in the Large Plasma Device (LaPD)

NASA Astrophysics Data System (ADS)

Dorfman, S. E.; Carter, T.; Pribyl, P.; Tripathi, S.; Van Compernolle, B.; Vincena, S. T.

2012-12-01

Alfvén waves, a fundamental mode of magnetized plasmas, are ubiquitous in lab and space. While the linear behaviour of these waves has been extensively studied [1], non-linear effects are important in many real systems, including the solar wind and solar corona. In particular, a parametric decay process in which a large amplitude Alfvén wave decays into an ion acoustic wave and backward propagating Alfvén wave may be key to the spectrum of solar wind turbulence. Ion acoustic waves have been observed in the heliosphere, but their origin and role have not yet been determined [2]. Such waves produced by parametric decay in the corona could contribute to coronal heating [3]. Parametric decay has also been suggested as an intermediate instability mediating the observed turbulent cascade of Alfvén waves to small spatial scales [4]. The present laboratory experiments aim to stimulate the parametric decay process by launching counter-propagating Alfvén waves from antennas placed at either end of the Large Plasma Device (LaPD). The resulting beat response has a dispersion relation consistent with an ion acoustic wave. Also consistent with a stimulated decay process: 1) The beat amplitude peaks when the frequency difference between the two Alfvén waves is near the value predicted by Alfvén-ion acoustic wave coupling. 2) This peak beat frequency scales with antenna and plasma parameters as predicted by three wave matching. 3) The beat amplitude peaks at the same location as the magnetic field from the Alfvén waves. 4) The beat wave is carried by the ions and propagates in the direction of the higher-frequency Alfvén wave. Strong damping observed after the pump Alfvén waves are turned off and observed heating of the plasma by the Alfvén waves are under investigation. [1] W. Gekelman, J. Geophys. Res., 104:14417-14436, July 1999. [2] A. Mangeney,et. al., Annales Geophysicae, Volume 17, Number 3 (1999). [3] F. Pruneti, F and M. Velli, ESA Spec. Pub. 404, 623 (1997). [4] P. Yoon and T. Fang, Plasma Phys. Control. Fusion 50 (2008). This work was performed at UCLA's Basic Plasma Science Facility, which is jointly supported by the U.S. DoE and NSF.

Ion acoustic shock wave in collisional equal mass plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adak, Ashish, E-mail: ashish-adak@yahoo.com; Ghosh, Samiran, E-mail: sran-g@yahoo.com; Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in

The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipationmore » that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.« less

Magnetosonic cnoidal waves and solitons in a magnetized dusty plasma

NASA Astrophysics Data System (ADS)

Kaur, Nimardeep; Singh, Manpreet; Saini, N. S.

2018-04-01

An investigation of magnetosonic nonlinear periodic (cnoidal) waves is presented in a magnetized electron-ion-dust ( e -i -d ) plasma having cold dust fluid with inertialess warm ions and electrons. The reductive perturbation method is employed to derive the Korteweg-de Vries equation. The dispersion relation for magnetosonic cnoidal waves is determined in the linear limit. The magnetosonic cnoidal wave solution is derived using the Sagdeev pseudopotential approach under the specific boundary conditions. There is the formation of only positive potential magnetosonic cnoidal waves and solitary structures in the high plasma-β limit. The effects of various plasma parameters, viz., plasma beta (β), σ (temperature ratio of electrons to ions), and μd (ratio of the number density of dust to electrons) on the characteristics of magnetosonic cnoidal waves are also studied numerically. The findings of the present investigation may be helpful in describing the characteristics of various nonlinear excitations in Earth's magnetosphere, solar wind, Saturn's magnetosphere, and space/astrophysical environments, where many space observations by various satellites confirm the existence of dust grains, highly energetic electrons, and high plasma-β.

Surface Josephson plasma waves in layered superconductors above the plasma frequency: evidence for a negative index of refraction.

PubMed

Golick, V A; Kadygrob, D V; Yampol'skii, V A; Rakhmanov, A L; Ivanov, B A; Nori, Franco

2010-05-07

We predict a new branch of surface Josephson plasma waves (SJPWs) in layered superconductors for frequencies higher than the Josephson plasma frequency. In this frequency range, the permittivity tensor components along and transverse to the layers have different signs, which is usually associated with negative refraction. However, for these frequencies, the bulk Josephson plasma waves cannot be matched with the incident and reflected waves in the vacuum, and, instead of the negative-refractive properties, abnormal surface modes appear within the frequency band expected for bulk modes. We also discuss the excitation of high-frequency SJPWs by means of the attenuated-total-reflection method.

Study on longitudinal dispersion relation in one-dimensional relativistic plasma: Linear theory and Vlasov simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, H.; Wu, S. Z.; Zhou, C. T.

2013-09-15

The dispersion relation of one-dimensional longitudinal plasma waves in relativistic homogeneous plasmas is investigated with both linear theory and Vlasov simulation in this paper. From the Vlasov-Poisson equations, the linear dispersion relation is derived for the proper one-dimensional Jüttner distribution. Numerically obtained linear dispersion relation as well as an approximate formula for plasma wave frequency in the long wavelength limit is given. The dispersion of longitudinal wave is also simulated with a relativistic Vlasov code. The real and imaginary parts of dispersion relation are well studied by varying wave number and plasma temperature. Simulation results are in agreement with establishedmore » linear theory.« less

Spatial distribution of the wave field of the surface modes sustaining filamentary discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lishev, St.; Shivarova, A.; Tarnev, Kh.

2008-01-01

The study presents the electrodynamical description of surface-wave-sustained discharges contracted in filamentary structures. The results are for the spatial distribution of the wave field and for the wave propagation characteristics obtained from a two-dimensional model developed for describing surface-wave behavior in plasmas with an arbitrary distribution of the plasma density. In accordance with the experimental observations of filamentary discharges, the plasma density distribution considered is completed by cylindrically shaped gas-discharge channels extended along the discharge length and positioned in the out-of-center region of the discharge, equidistantly in an azimuthal direction. Due to the two-dimensional inhomogeneity of the plasma density ofmore » the filamentary structure, the eigen surface mode of the structure is a hybrid wave, with all--six--field components. For identification of its behavior, the surface wave properties in the limiting cases of a plasma ring and a single filament--both radially inhomogeneous--are involved in the discussions. The presentation of the results is for filamentary structures with a decreasing number of filaments (from 10 to 2) starting with the plasma ring, the latter supporting propagation of an azimuthally symmetric wave. Due to the resonance absorption of the surface waves, always present because of the smooth variation of the plasma density, the contours of the critical density are those guiding the surface wave propagation. Decreasing number of filaments in the structure leads to localization of the amplitudes of the wave-field components around the filaments. By analogy with the spatial distribution of the wave field in the plasma ring, the strong resonance enhancement of the wave-field components is along that part of the contour of the critical density which is far off the center of the filamentary structure. The analysis of the spatial distribution of the field components of the filamentary structure shows that the hybrid wave is an eigenmode of the whole structure, i.e., the wave field does not appear as a superposition of fields of eigenmodes of the separated filaments completing it. It is stressed that the spatial distribution of the field components of the eigen hybrid mode of the filamentary structure has an azimuthally symmetric background field.« less

A theoretical study of hot plasma spheroids in the presence of low-frequency electromagnetic waves

NASA Astrophysics Data System (ADS)

Ahmadizadeh, Y.; Jazi, B.; Barjesteh, S.

2016-07-01

While taking into account thermal motion of electrons, scattering of electromagnetic waves with low frequency from hot plasma spheroids is investigated. In this theoretical research, ions are heavy to respond to electromagnetic fluctuations. The solution of scalar wave equation in spheroidal coordinates for electric potential inside the plasma spheroids are obtained. The variations of resonance frequencies vs. Debye length are studied and consistency between the obtained results in this paper and the results for the well-known plasma objects such as plasma column and spherical plasma have been proved.

Stimulated Parametric Decay of Large Amplitude Alfv'en waves in the Large Plasma Device (LaPD)

NASA Astrophysics Data System (ADS)

Dorfman, S.; Carter, T.; Pribyl, P.; Tripathi, S. K. P.; van Compernolle, B.; Vincena, S.

2012-10-01

Alfv'en waves, the fundamental mode of magnetized plasmas, are ubiquitous in lab and space. While the linear behaviour of these waves has been extensively studied, non-linear effects are important in many real systems. In particular, a parametric decay process in which a large amplitude Alfv'en wave decays into an ion acoustic wave and backward propagating Alfv'en wave may be key to the spectrum of solar wind turbulence. The present laboratory experiments aim to stimulate this process by launching counter-propagating Alfv'en waves from antennas placed at either end of the Large Plasma Device (LaPD). The resulting beat response has many properties consistent with an ion acoustic wave including: 1) The beat amplitude peaks when the frequency difference between the two Alfv'en waves is near the value predicted by Alfv'en-ion acoustic wave coupling. 2) This peak beat frequency scales with antenna and plasma parameters as predicted by three wave matching. 3) The beat amplitude peaks at the same location as the magnetic field from the Alfv'en waves. 4) The beat wave is carried by the ions and propagates in the direction of the higher-frequency Alfv'en wave. Strong damping observed after the pump Alfv'en waves are turned off is under investigation.

Reflection of Fast Magnetosonic Waves near a Magnetic Reconnection Region

NASA Astrophysics Data System (ADS)

Provornikova, E.; Laming, J. M.; Lukin, V. S.

2018-06-01

Magnetic reconnection in the solar corona is thought to be unstable with the formation of multiple interacting plasmoids, and previous studies have shown that plasmoid dynamics can trigger MHD waves of different modes propagating outward from the reconnection site. However, variations in plasma parameters and magnetic field strength in the vicinity of a coronal reconnection site may lead to wave reflection and mode conversion. In this paper we investigate the reflection and refraction of fast magnetoacoustic waves near a reconnection site. Under a justified assumption of an analytically specified Alfvén speed profile, we derive and solve analytically the full wave equation governing the propagation of fast-mode waves in a non-uniform background plasma without recourse to the small wavelength approximation. We show that the waves undergo reflection near the reconnection current sheet due to the Alfvén speed gradient and that the reflection efficiency depends on the plasma-β parameter, as well as on the wave frequency. In particular, we find that waves are reflected more efficiently near reconnection sites in a low-β plasma, which is typical under solar coronal conditions. Also, the reflection is larger for lower-frequency waves while high-frequency waves propagate outward from the reconnection region almost without the reflection. We discuss the implications of efficient wave reflection near magnetic reconnection sites in strongly magnetized coronal plasma for particle acceleration, and also the effect this might have on first ionization potential (FIP) fractionation by the ponderomotive force of these waves in the chromosphere.

Electric field strength determination in filamentary DBDs by CARS-based four-wave mixing

NASA Astrophysics Data System (ADS)

Boehm, Patrick; Kettlitz, Manfred; Brandenburg, Ronny; Hoeft, Hans; Czarnetzki, Uwe

2016-09-01

The electric field strength is a basic parameter of non-thermal plasmas. Therefore, a profound knowledge of the electric field distribution is crucial. In this contribution a four wave mixing technique based on Coherent Anti-Stokes Raman spectroscopy (CARS) is used to measure electric field strengths in filamentary dielectric barrier discharges (DBDs). The discharges are operated with a pulsed voltage in nitrogen at atmospheric pressure. Small amounts hydrogen (10 vol%) are admixed as tracer gas to evaluate the electric field strength in the 1 mm discharge gap. Absolute values of the electric field strength are determined by calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. Alteration of the electric field strength has been observed during the internal polarity reversal and the breakdown process. In this case the major advantage over emission based methods is that this technique can be used independently from emission, e.g. in the pre-phase and in between two consecutive, opposite discharge pulses where no emission occurs at all. This work was supported by the Deutsche Forschungsgemeinschaft, Forschergruppe FOR 1123 and Sonderforschungsbereich TRR 24 ``Fundamentals of complex plasmas''.

System and method for generating current by selective minority species heating

DOEpatents

Fisch, Nathaniel J.

1983-01-01

A system for the generation of toroidal current in a plasma which is prepared in a toroidal magnetic field. The system utilizes the injection of low-frequency waves into the plasma by means of phased antenna arrays or phased waveguide arrays. The plasma is prepared with a minority ion species of different charge state and different gyrofrequency from the majority ion species. The wave frequency and wave phasing are chosen such that the wave energy is absorbed preferentially by minority species ions traveling in one toroidal direction. The absorption of energy in this manner produces a toroidal electric current even when the injected waves themselves do not have substantial toroidal momentum. This current can be continuously maintained at modest cost in power and may be used to confine the plasma. The system can operate efficiently on fusion grade tokamak plasmas.

A generalized plasma dispersion function for electron damping in tokamak plasmas

DOE PAGES

Berry, L. A.; Jaeger, E. F.; Phillips, C. K.; ...

2016-10-14

Radio frequency wave propagation in finite temperature, magnetized plasmas exhibits a wide range of physics phenomena. The plasma response is nonlocal in space and time, and numerous modes are possible with the potential for mode conversions and transformations. Additionally, diffraction effects are important due to finite wavelength and finite-size wave launchers. Multidimensional simulations are required to describe these phenomena, but even with this complexity, the fundamental plasma response is assumed to be the uniform plasma response with the assumption that the local plasma current for a Fourier mode can be described by the Stix conductivity. But, for plasmas with non-uniformmore » magnetic fields, the wave vector itself is nonlocal. When resolved into components perpendicular (k ) and parallel (k ||) to the magnetic field, locality of the parallel component can easily be violated when the wavelength is large. The impact of this inconsistency is that estimates of the wave damping can be incorrect (typically low) due to unresolved resonances. For the case of ion cyclotron damping, this issue has already been addressed by including the effect of parallel magnetic field gradients. In this case, a modified plasma response (Z function) allows resonance broadening even when k || = 0, and this improves the convergence and accuracy of wave simulations. In our paper, we extend this formalism to include electron damping and find improved convergence and accuracy for parameters where electron damping is dominant, such as high harmonic fast wave heating in the NSTX-U tokamak, and helicon wave launch for off-axis current drive in the DIII-D tokamak.« less

Properties of Langmuir wave bursts associated with magnetic holes

NASA Technical Reports Server (NTRS)

MacDowall, R. J.; Lin, N.; Kellogg, P. J.; Phillips, J. L.; Neugebauer, M.; Balogh, A.; Forsyth, R. J.

1995-01-01

The radio and plasma wave receivers on the Ulysses spacecraft have detected thousands of short-duration bursts of waves at approximately the electron plasma frequency. These wave events believed to be Langmuir waves are usually less than approximately 5 minutes in duration. They occur in or at the boundaries of depletions in the magnetic field amplitude known as magnetic holes. Using the 16 sec time resolution provided by the plasma frequency receiver, it is possible to examine the density structure inside of magnetic holes. Even higher time resolutions are sometimes available from the radio receiver data. The Ulysses observations show that these wave bursts occur more frequently at high heliographic latitudes; the occurrence rates depend on both latitude and distance from the Sun. We review the statistics for the wave events, compare them to magnetic and plasma parameters, and review the reasons for the more frequent occurrence at high heliographic latitudes.

Higher order contribution to the propagation characteristics of low frequency transverse waves in a dusty plasma

NASA Astrophysics Data System (ADS)

Misra, A. P.; Chowdhury, A. Roy; Paul, S. N.

2004-09-01

Characteristic features of low frequency transverse wave propagating in a magnetised dusty plasma have been analysed considering the effect of dust-charge fluctu- ation. The distinctive behaviours of both the left circularly polarised and right circularly polarised waves have been exhibited through the analysis of linear and non-linear disper- sion relations. The phase velocity, group velocity, and group travel time for the waves have been obtained and their propagation characteristics have been shown graphically with the variations of wave frequency, dust density and amplitude of the wave. The change in non-linear wave number shift and Faraday rotation angle have also been exhibited with respect to the plasma parameters. It is observed that the effects of dust particles are significant only when the higher order contributions are considered. This may be referred to as the `dust regime' in plasma.

Experimental Measurement of the Nonlinear Interaction between Counterpropagating Alfv'en Waves in the LaPD

NASA Astrophysics Data System (ADS)

Schroeder, J. W. R.; Drake, D. J.; Howes, G. G.; Skiff, F.; Kletzing, C. A.; Carter, T. A.; Dorfman, S.; Auerbach, D.

2012-10-01

Turbulence plays an important role in the transport of mass and energy in many space and astrophysical plasmas ranging from galaxy clusters to Earth's magnetosphere. One active topic of research is the application of idealized Alfv'enic turbulence models to plasma conditions relevant to space and astrophysical plasmas. Alfv'enic turbulence models based on incompressible magnetohydrodynamics (MHD) contain a nonlinear interaction that drives the cascade of energy to smaller scales. We describe experiments at the Large Plasma Device (LaPD) that focus on the interaction of an Alfv'en wave traveling parallel to the mean magnetic field with a counterpropagating Alfv'en wave. Theory predicts the nonlinear interaction of the two primary waves will produce a secondary daughter Alfv'en wave. In this study, we present the first experimental identification of the daughter wave generated by nonlinear interactions between the primary Alfv'en waves.

Nonlinear wave interactions in shallow water magnetohydrodynamics of astrophysical plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klimachkov, D. A., E-mail: klimachkovdmitry@gmail.com; Petrosyan, A. S., E-mail: apetrosy@iki.rssi.ru

2016-05-15

The rotating magnetohydrodynamic flows of a thin layer of astrophysical and space plasmas with a free surface in a vertical external magnetic field are considered in the shallow water approximation. The presence of a vertical external magnetic field changes significantly the dynamics of wave processes in an astrophysical plasma, in contrast to a neutral fluid and a plasma layer in an external toroidal magnetic field. There are three-wave nonlinear interactions in the case under consideration. Using the asymptotic method of multiscale expansions, we have derived nonlinear equations for the interaction of wave packets: three magneto- Poincare waves, three magnetostrophic waves,more » two magneto-Poincare and one magnetostrophic waves, and two magnetostrophic and one magneto-Poincare waves. The existence of decay instabilities and parametric amplification is predicted. We show that a magneto-Poincare wave decays into two magneto-Poincare waves, a magnetostrophic wave decays into two magnetostrophic waves, a magneto-Poincare wave decays into one magneto-Poincare and one magnetostrophic waves, and a magnetostrophic wave decays into one magnetostrophic and one magneto-Poincare waves. There are the following parametric amplification mechanisms: the parametric amplification of magneto-Poincare waves, the parametric amplification of magnetostrophic waves, the amplification of a magneto-Poincare wave in the field of a magnetostrophic wave, and the amplification of a magnetostrophic wave in the field of a magneto-Poincare wave. The instability growth rates and parametric amplification factors have been found for the corresponding processes.« less

Bending of solitons in weak and slowly varying inhomogeneous plasma

NASA Astrophysics Data System (ADS)

Mukherjee, Abhik; Janaki, M. S.; Kundu, Anjan

2015-12-01

The bending of solitons in two dimensional plane is presented in the presence of weak and slowly varying inhomogeneous ion density for the propagation of ion acoustic soliton in unmagnetized cold plasma with isothermal electrons. Using reductive perturbation technique, a modified Kadomtsev-Petviashvili equation is obtained with a chosen unperturbed ion density profile. The exact solution of the equation shows that the phase of the solitary wave gets modified by a function related to the unperturbed inhomogeneous ion density causing the soliton to bend in the two dimensional plane, while the amplitude of the soliton remains constant.

Bending of solitons in weak and slowly varying inhomogeneous plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukherjee, Abhik, E-mail: abhik.mukherjee@saha.ac.in; Janaki, M. S., E-mail: ms.janaki@saha.ac.in; Kundu, Anjan, E-mail: anjan.kundu@saha.ac.in

2015-12-15

The bending of solitons in two dimensional plane is presented in the presence of weak and slowly varying inhomogeneous ion density for the propagation of ion acoustic soliton in unmagnetized cold plasma with isothermal electrons. Using reductive perturbation technique, a modified Kadomtsev-Petviashvili equation is obtained with a chosen unperturbed ion density profile. The exact solution of the equation shows that the phase of the solitary wave gets modified by a function related to the unperturbed inhomogeneous ion density causing the soliton to bend in the two dimensional plane, while the amplitude of the soliton remains constant.

Direct Coating of Nanocrystalline Diamond on Steel

NASA Astrophysics Data System (ADS)

Tsugawa, Kazuo; Kawaki, Shyunsuke; Ishihara, Masatou; Hasegawa, Masataka

2012-09-01

Nanocrystalline diamond films have been successfully deposited on stainless steel substrates without any substrate pretreatments to promote diamond nucleation, including the formation of interlayers. A low-temperature growth technique, 400 °C or lower, in microwave plasma chemical vapor deposition using a surface-wave plasma has cleared up problems in diamond growth on ferrous materials, such as the surface graphitization, long incubation time, substrate softening, and poor adhesion. The deposited nanocrystalline diamond films on stainless steel exhibit good adhesion and tribological properties, such as a high wear resistance, a low friction coefficient, and a low aggression strength, at room temperature in air without lubrication.

Low frequency wave propagation in a cold magnetized dusty plasma

NASA Astrophysics Data System (ADS)

Sarkar, S.; Ghosh, S.; Khan, M.

1998-12-01

In this paper several characteristics of low frequency waves in a cold magnetized dusty plasma propagating parallel and perpendicular to the static background magnetic field have been investigated. In the case of parallel propagation the negatively charged dust particles resonate with the right circularly polarized (RCP) component of em waves when the wave frequency equals the dust cyclotron frequency. It has been shown that an RCP wave in dusty plasma consists of two branches and there exists a region where an RCP wave propagation is not possible. Dispersion relation, phase velocity and group velocity of RCP waves have been obtained and propagation characteristics have been shown graphically. Poynting flux and Faraday rotation angles have been calculated for both lower and upper branches of the RCP wave. It has been observed that sense of rotation of the plane of polarization of the RCP wave corresponding to two distinct branches are opposite. Finally, the effect of dust particles on the induced magnetization from the inverse Faraday effect (IFE) due to the interaction of low frequency propagating and standing em waves with dusty plasmas has been evaluated.

Plasma waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vandenplas, P.E.

1996-03-01

This paper presents a summary of important parts of `Plasma waves` by J.F. Denisse and J.L.Delcroix, Interscience-Wiley, 1963, itself a translation of `Theorie des Ondes dans les Plasmas`, Dunod, 1959. We shall, however, use S.I. units instead of cgs ones and adopt where necessary more modern notations. A rather complete overview of the complexity of waves in a hot magnetized plasma is given. The effects of collisions have been mostly neglected. 1 fig.

Pondermotive versus mirror force in creation of the filamentary cavities in auroral plasma

NASA Technical Reports Server (NTRS)

Singh, Nagendra

1994-01-01

Recently rocket observations on spikelets of lower-hybrid waves along with strong density cavities and transversely heated ions were reported. The observed thin filamentary cavities oriented along the magnetic field in the auroral plasma have density depletions up to several tens of percent. These observations have been interpreted in terms of a theory for lower-hybrid wave condensation and collapse. The modulational instability leading to the wave consensation of the lower-hybrid waves yields only weak density perturbations, which cannot explain the above strong density depletions. The wave collapse theory is based on the nonlinear pondermotive force in a homogeneous ambient plasma and the density depletion is determined by the balance between the wave pressure (pondermotive force) and the plasma pressure. In the auroral plasma, the balance is achieved in a time tau(sub wc) equal to or less than 1 ms. It is shown here that the mirror force, acting on the transversely heated ions at a relatively long time scale, is an effective mechanism for creating the strong plasma cavities. We suggest that the process of wave condensation, through the pondermotive force causing generation of short wavelength waves from relatively long wavelength waves, is a dominant process until the former waves evolve and become effective in the transverse heating of ions. As soon as this happens, mirror force on ions becomes an important factor in the creation of the density cavities, which may further trap and enhance the waves. Results from a model of cavity formation by transverse ion heating show that the observed depletions in the density cavities can be produced by the heating rates determined by the observed wave amplitudes near the lower-hybrid frequency. It is found that the creation of a strong density cavity takes a few minutes.

Magnetic Field Effects and Electromagnetic Wave Propagation in Highly Collisional Plasmas.

NASA Astrophysics Data System (ADS)

Bozeman, Steven Paul

The homogeneity and size of radio frequency (RF) and microwave driven plasmas are often limited by insufficient penetration of the electromagnetic radiation. To investigate increasing the skin depth of the radiation, we consider the propagation of electromagnetic waves in a weakly ionized plasma immersed in a steady magnetic field where the dominant collision processes are electron-neutral and ion-neutral collisions. Retaining both the electron and ion dynamics, we have adapted the theory for cold collisionless plasmas to include the effects of these collisions and obtained the dispersion relation at arbitrary frequency omega for plane waves propagating at arbitrary angles with respect to the magnetic field. We discuss in particular the cases of magnetic field enhanced wave penetration for parallel and perpendicular propagation, examining the experimental parameters which lead to electromagnetic wave propagation beyond the collisional skin depth. Our theory predicts that the most favorable scaling of skin depth with magnetic field occurs for waves propagating nearly parallel to B and for omega << Omega_{rm e} where Omega_{rm e} is the electron cyclotron frequency. The scaling is less favorable for propagation perpendicular to B, but the skin depth does increase for this case as well. Still, to achieve optimal wave penetration, we find that one must design the plasma configuration and antenna geometry so that one generates primarily the appropriate angles of propagation. We have measured plasma wave amplitudes and phases using an RF magnetic probe and densities using Stark line broadening. These measurements were performed in inductively coupled plasmas (ICP's) driven with a standard helical coil, a reverse turn (Stix) coil, and a flat spiral coil. Density measurements were also made in a microwave generated plasma. The RF magnetic probe measurements of wave propagation in a conventional ICP with wave propagation approximately perpendicular to B show an increase in skin depth with magnetic field and a damping of the effect of B with pressure. The flat coil geometry which launches waves more nearly parallel to B allows enhanced wave penetration at higher pressures than the standard helical coil.

Correlation of wave propagation modes in helicon plasma with source tube lengths

NASA Astrophysics Data System (ADS)

Niu, Chen; Zhao, Gao; Wang, Yu; Liu, Zhongwei; Chen, Qiang

2017-01-01

Helicon wave plasma demonstrates lots of advantages in high coupling efficiency, high density, and low magnetic field. However, the helicon wave plasma still meets challenges in applications of material deposition, surface treatment, and electromagnetic thrusters owing to the changeable coupled efficiency and the remarkable non-uniformity. In this paper, we explore the wave propagation characterization by the B-dot probe in various lengths of source tubes. We find that in a long source tube the standing wave appears under the antenna zone, while the traveling wave is formed out of the antenna region. The apparent modulation of wave amplitude is formed in upstream rather than in downstream of the antenna. In a short source tube, however, there is only standing wave propagation.

Vlasov Simulation of the Effects of Collisions on the Damping of Electron Plasma Waves

NASA Astrophysics Data System (ADS)

Banks, Jeff; Berger, Richard; Chapman, Thomas; Brunner, Stephan; Tran, T.

2015-11-01

Kinetic simulation of two dimensional plasma waves through direct discretization of the Vlasov equation may be particularly attractive for situations where minimal numerical fluctuation levels are desired, such as when measuring growth rates of plasma wave instabilities. In many cases collisional effects can be important to the evolution of plasma waves because they both set a minimum damping rate for plasma waves and can scatter particles out of resonance through pitch angle scattering. Here we present Vlasov simulations of evolving electron plasma waves (EPWs) in plasmas of varying collisionality. We consider first the effects of electron-ion pitch angle collisions on the frequency and damping, Landau and collisional, of small-amplitude EPWs for a range of collision rates. In addition, the wave phase velocities are extracted from the simulation results and compared with theory. For this study we use the Eulerian-based kinetic code LOKI that evolves the Vlasov-Poisson system in 2+2-dimensional phase space. We then discuss extensions of the collision operator to include thermalization. Discretization of these collision operators using 4th order accurate conservative finite-differencing will be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the LDRD program at LLNL under project tracking code 15-ERD-038.

Identical Collision Terms/Solutions of Kinetic Eqn. and Explanation of Damping of Waves in Plasmas and Solids Known by Different Names

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, S. K.

2010-11-23

In this paper we show that identical collision terms are known by different names in gaseous plasmas and solids. Method used by plasma physicists and the one used by solid state physicists to solve Kinetic equation are also exactly same but they are also known by different names. In fact the physical explanation of damping of plasma Waves given by plasma physicists is quite similar to that given by solid state physicists to explain the absorption of acoustic waves in solids.

The role of cold plasma and its composition on the growth of electromagnetic ion cyclotron waves in the inner magnetosphere

NASA Astrophysics Data System (ADS)

Snelling, J. M.; Johnson, J.; Engebretson, M. J.; Kim, E. H.; Tian, S.

2017-12-01

While it is currently well accepted that the free energy for growth of electromagnetic ion cyclotron (EMIC) waves in Earth's magnetosphere comes from unstable configurations of hot anisotropic ions that are injected into the ring current, several questions remain about what controls the instability. A recent study of the occurrence of EMIC waves relative to the plasmapause in Vallen Probes Data showed that plasma density gradients or enhancements were not the dominant factor in determining the site of EMIC wave generation [Tetrick et al. 2017]. However, the factors that control wave growth on each of the branches are not fully understood. For example, in some cases, the measured anisotropy is not adequate to explain local instability, and the relative importance of the density and composition of a cold plasma population is still uncertain. Several intervals of EMIC wave activity are analyzed to determine the role of a cold population in driving instability on each of the wave branches. This study utilizes the WHAMP (Waves in Homogeneous Anisotropic Magnetized Plasma) stability code with plasma distributions optimized to fit the observed distributions including temperature anisotropy, loss cone, and ring beam populations.

Effect of turbulence on the dissipation of the space-charge wave in a bounded turbulent plasma column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588

The dispersion relation and the dissipation process of the space-charge wave propagating in a bounded plasma such as a cylindrical waveguide are investigated by employing the longitudinal dielectric permittivity that contains the diffusivity based on the Dupree theory of turbulent plasma. We derived the dispersion relation for space-charge wave in terms of the radius of cylindrical waveguide and the roots of the Bessel function of the first kind which appears as the boundary condition. We find that the wave frequency for a lower-order root of the Bessel function is higher than that of a higher-order root. We also find thatmore » the dissipation is greatest for the lowest-order root, but it is suppressed significantly as the order of the root increases. The wave frequency and the dissipation process are enhanced as the radius of cylindrical waveguide increases. However, they are always smaller than the case of bulk plasma. We find that the diffusivity of turbulent plasma would enhance the damping of space-charge waves, especially, in the range of small wave number. For a large wave number, the diffusivity has little effect on the damping.« less

Modified dust ion-acoustic surface waves in a semi-bounded magnetized plasma containing the rotating dust grains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588

2016-05-15

The dispersion relation for modified dust ion-acoustic surface waves in the magnetized dusty plasma containing the rotating dust grains is derived, and the effects of magnetic field configuration on the resonant growth rate are investigated. We present the results that the resonant growth rates of the wave would increase with the ratio of ion plasma frequency to cyclotron frequency as well as with the increase of wave number for the case of perpendicular magnetic field configuration when the ion plasma frequency is greater than the dust rotation frequency. For the parallel magnetic field configuration, we find that the instability occursmore » only for some limited ranges of the wave number and the ratio of ion plasma frequency to cyclotron frequency. The resonant growth rate is found to decrease with the increase of the wave number. The influence of dust rotational frequency on the instability is also discussed.« less

The impact of positrons beam on the propagation of super freak waves in electron-positron-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali Shan, S.; National Centre for Physics; Pakistan Institute of Engineering and Applied Sciences

2016-07-15

In this work, we examine the nonlinear propagation of planar ion-acoustic freak waves in an unmagnetized plasma consisting of cold positive ions and superthermal electrons subjected to cold positrons beam. For this purpose, the reductive perturbation method is used to derive a nonlinear Schrödinger equation (NLSE) for the evolution of electrostatic potential wave. We determine the domain of the plasma parameters where the rogue waves exist. The effect of the positron beam on the modulational instability of the ion-acoustic rogue waves is discussed. It is found that the region of the modulational stability is enhanced with the increase of positronmore » beam speed and positron population. Second as positrons beam increases the nonlinearities of the plasma system, large amplitude ion acoustic rogue waves are pointed out. The present results will be helpful in providing a good fit between the theoretical analysis and real applications in future laboratory plasma experiments.« less

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave

DOE PAGES

Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; ...

2017-03-31

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA’s Magnetospheric Multiscale (MMS) mission, we utilize Earth’s magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electronsmore » confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. As a result, the investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.« less

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA’s Magnetospheric Multiscale (MMS) mission, we utilize Earth’s magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electronsmore » confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. As a result, the investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.« less

Computational study of nonlinear plasma waves. [plasma simulation model applied to electrostatic waves in collisionless plasma

NASA Technical Reports Server (NTRS)

Matsuda, Y.

1974-01-01

A low-noise plasma simulation model is developed and applied to a series of linear and nonlinear problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. It is demonstrated that use of the hybrid simulation model allows economical studies to be carried out in both the linear and nonlinear regimes with better quantitative results, for comparable computing time, than can be obtained by conventional particle simulation models, or direct solution of the Vlasov equation. The characteristics of the hybrid simulation model itself are first investigated, and it is shown to be capable of verifying the theoretical linear dispersion relation at wave energy levels as low as .000001 of the plasma thermal energy. Having established the validity of the hybrid simulation model, it is then used to study the nonlinear dynamics of monochromatic wave, sideband instability due to trapped particles, and satellite growth.

Observations of whistler mode waves in the Jovian system and their consequences for the onboard processing within the RPWI instrument for JUICE

NASA Astrophysics Data System (ADS)

Santolik, O.; Soucek, J.; Kolmasova, I.; Grison, B.; Wahlund, J.-E.; Bergmann, J.

2013-09-01

Evidence for a magnetosphere at Ganymede has been found in 1996 using measurements of plasma waves onboard the Galileo spacecraft (fig. 1). This discovery demonstrates the importance of measurements of waves in plasmas around Jovian moons [1]. Galileo also observed whistler-mode waves in the magnetosphere of Ganymede similar to important classes of waves in the Earth magnetosphere: chorus and hiss [2]. Data from the Galileo spacecraft have therefore shown the importance of measurements of waves in plasmas around Jovian moons, especially in the light of recent advances in analysis of whistler-mode waves in the Earth magnetosphere and their importance for acceleration of radiation belt electrons to relativistic energies. Multicomponent measurements of the fluctuating magnetic and electric fields are needed for localization and characterization of source regions of these waves. Radio & Plasma Waves Investigation (RPWI) experiment will be implemented on the JUICE (JUpiter ICy moon Explorer) spacecraft. RPWI is a highly integrated instrument package that provides a comprehensive set of plasma and fields measurements. Proposed measurement modes for the low frequency receiver subsystem of RPWI include onboard processing which will be suitable for analysis of whistler-mode waves: (1) Polarization and propagation analysis based on phase relations to identify wave modes and propagation directions (2) Poynting vector to determine source regions (3) Detailed frequency-time structure, polarization, wave vector directions to identify linear or nonlinear source mechanisms

An impedance analysis of double-stream interaction in semiconductors

NASA Technical Reports Server (NTRS)

Chen, P. W.; Durney, C. H.

1972-01-01

The electromagnetic waves propagating through a drifting semiconductor plasma are studied from a macroscopic point of view in terms of double-stream interaction. The possible existing waves (helicon waves, longitudinal waves, ordinary waves, and pseudolongitudinal waves) which depend upon the orientation of the dc external magnetic field are derived. A powerful impedance concept is introduced to investigate the wave behavior of longitudinal (space charge) waves or pseudolongitudinal waves in a semiconductor plasma. The impedances due to one- and two-carrier stream interactions were calculated theoretically.

Nonlinear low frequency electrostatic structures in a magnetized two-component auroral plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rufai, O. R., E-mail: rajirufai@gmail.com; Scientific Computing, Memorial University of Newfoundland, St John's, Newfoundland and Labrador A1C 5S7; Bharuthram, R., E-mail: rbharuthram@uwc.ac.za

2016-03-15

Finite amplitude nonlinear ion-acoustic solitons, double layers, and supersolitons in a magnetized two-component plasma composed of adiabatic warm ions fluid and energetic nonthermal electrons are studied by employing the Sagdeev pseudopotential technique and assuming the charge neutrality condition at equilibrium. The model generates supersoliton structures at supersonic Mach numbers regime in addition to solitons and double layers, whereas in the unmagnetized two-component plasma case only, soliton and double layer solutions can be obtained. Further investigation revealed that wave obliqueness plays a critical role for the evolution of supersoliton structures in magnetized two-component plasmas. In addition, the effect of ion temperaturemore » and nonthermal energetic electron tends to decrease the speed of oscillation of the nonlinear electrostatic structures. The present theoretical results are compared with Viking satellite observations.« less

Nonlinear absorption of short intense laser pulse in multispecies plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kargarian, A.; Hajisharifi, K.; Mehdian, H.

In the present paper, the detailed investigation concerning the effect of inclusion of heavy negative ions into the finite background plasma on the laser absorption has been carried out by employing particle-in-cell simulation method. For this purpose, in this configuration, the laser energy absorption relying on the nonlinear phenomena such as phase-mixing, wave-breaking, and scattering has been studied in the Raman-Brillouin regime. It is shown that the inclusion of heavy negative ions suppresses the scattering while increases the phase-mixing time. Moreover, it is illustrated that this inclusion can increase the laser absorption in finite plasma environment, after saturation. The obtainedmore » results are expected to be relevant to the experiments on the mass spectrometry with laser desorption techniques as well as on the laser-plasma interaction with application to particles acceleration.« less

Nonlinear Korteweg-de Vries equation for soliton propagation in relativistic electron-positron-ion plasma with thermal ions

NASA Astrophysics Data System (ADS)

Saeed, R.; Shah, Asif; Noaman-Ul-Haq, Muhammad

2010-10-01

The nonlinear propagation of ion-acoustic solitons in relativistic electron-positron-ion plasma comprising of Boltzmannian electrons, positrons, and relativistic thermal ions has been examined. The Korteweg-de Vries equation has been derived by reductive perturbation technique. The effect of various plasma parameters on amplitude and structure of solitary wave is investigated. The pert graphical view of the results has been presented for illustration. It is observed that increase in the relativistic streaming factor causes the soliton amplitude to thrive and its width shrinks. The soliton amplitude and width decline as the ion to electron temperature ratio is increased. The increase in positron concentration results in reduction of soliton amplitude. The soliton amplitude enhances as the electron to positron temperature ratio is increased. Our results may have relevance in the understanding of astrophysical plasmas.

Modeling and Theory of RF Antenna Systems on Proto-MPEX

NASA Astrophysics Data System (ADS)

Piotrowicz, P. A.; Caneses, J. F.; Goulding, R. H.; Green, D.; Caughman, J. B. O.; Ruzic, D. N.; Proto-MPEX Team

2017-10-01

The RF wave coupling of the helicon and ICH antennas installed on the Prototype Material Plasma Exposure eXperiment (MPEX) has been explored theoretically and via a full wave model implemented in COMSOL Multiphysics. The high-density mode in Proto-MPEX has been shown to occur when exciting radial eigenmodes of the plasma column which coincides with entering a Trivelpiece Gould (TG) anti-resonant regime, therefore suppressing edge heating in favor of core power deposition. The fast wave launched by the helicon antenna has a large wavelength and travels at a steep group velocity angle with the background magnetic field; for this reason the fast wave launched by the helicon antenna efficiently couples power to the core plasma. However, the ICH heating scheme relies on a small wavelength slow wave to couple power to the core of the plasma column. Coupling slow wave power to the core of the plasma column is sensitive to the location of the Alfven resonance. The wave-vector and group velocity vector of the slow wave in this parameter regime undergoes a drastic change in behavior when approaching the Alfven resonance. Full wave simulation results and dispersion analysis will be presented with suggestions to guide experimental progress. This work was supported by the US. D.O.E. contract DE-AC05-00OR22725.

Analysis of band structure, transmission properties, and dispersion behavior of THz wave in one-dimensional parabolic plasma photonic crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Askari, Nasim; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir; Mirzaie, Reza

2015-11-15

The photonic band gap of obliquely incident terahertz electromagnetic waves in a one-dimensional plasma photonic crystal is studied. The periodic structure consists of lossless dielectric and inhomogeneous plasma with a parabolic density profile. The dispersion relation and the THz wave transmittance are analyzed based on the electromagnetic equations and transfer matrix method. The dependence of effective plasma frequency and photonic band gap characteristics on dielectric and plasma thickness, plasma density, and incident angle are discussed in detail. A theoretical calculation for effective plasma frequency is presented and compared with numerical results. Results of these two methods are in good agreement.

Observation of frequency cutoff for self-excited dust acoustic waves

NASA Astrophysics Data System (ADS)

Nosenko, V.; Zhdanov, S. K.; Morfill, G. E.; Kim, S.-H.; Heinrich, J.; Merlino, R. L.

2009-11-01

Complex (dusty) plasmas consist of fine solid particles suspended in a weakly ionized gas. Complex plasmas are excellent model systems to study wave phenomena down to the level of individual ``atoms''. Spontaneously excited dust acoustic waves were observed with high temporal resolution in a suspension of micron-size kaolin particles in a dc discharge in argon. Wave activity was found at frequencies as high as 400 Hz. At high wave numbers, the wave dispersion relation was acoustic-like (frequency proportional to wave number). At low wave numbers, the wave frequency did not tend to zero, but reached a cutoff frequency fc instead. The value of fc declined with distance from the anode. We propose a simple model that explains the observed cutoff by particle confinement in plasma. The existence of a cutoff frequency is very important for the propagation of waves: the waves excited above fc are propagating, and those below fc are evanescent.

Transitional properties of supersolitons in a two electron temperature warm multi-ion plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varghese, Steffy S., E-mail: steffy13@iigs.iigm.res.in; Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in

The existence domain of an ion acoustic supersoliton and its transition to a regular kind of solitary wave have been explored in detail using Sagdeev pseudopotential technique for a two electron temperature warm multi-ion plasma having two species of ions. It was found that both the cold to hot electron temperature ratio and their respective ambient densities play a deterministic role for the existence of a supersoliton, as well as its transitional processes to a regular solitary wave. Analogous to a double layer solution, which often marks the boundary of the existence domain of a regular solitary wave, a “curvemore » of inflection” determines the boundary of the existence domain of a supersoliton. The characteristics of the “curve of inflection,” in turn, depend on the respective concentrations of the two ion species. It is observed that the supersolitons are actually a subset of a more general kind of solutions which are characterized by a fluctuation in the corresponding charge separation which precedes their maximum amplitude. It is also observed that these novel kinds of solitary structures, including supersolitons, occur only for a very narrow range of parameters near constant amplitude beyond which the wave breaks.« less

Mid-latitude Narrowband Stimulated Electromagnetic Emissions (NSEE): New Observations and Modeling

NASA Astrophysics Data System (ADS)

Nossa, E.; Mahmoudian, A.; Isham, B.; Bernhardt, P. A.; Briczinski, S. J., Jr.

2017-12-01

High power electromagnetic waves (EM) transmitted from the ground interact with the local plasma in the ionosphere and can produce Stimulated Electromagnetic Emissions (SEE) through the parametric decay instability (PDI). The classical SEE features known as wideband SEE (WSEE) with frequency offset of 1 kHz up to 100 kHz have been observed and studied in detail in the 1980s and 1990s. A new era of ionospheric remote sensing techniques was begun after the recent update of the HF transmitter at the HAARP. Sideband emissions of unprecedented strength have been reported during recent campaigns at HAARP, reaching up to 10 dB relative to the reflected pump wave which are by far the strongest spectral features of secondary radiation that have been reported. These emissions known as narrowband SEE (NSEE) are shifted by only up to a few tens of Hertz from radio-waves transmitted at several megahertz. One of these new NSEE features are emission lines within 100 Hz of the pump frequency and are produced through magnetized stimulated Brillouin scatter (MSBS) process. Stimulated Brillouin Scatter (SBS) is a strong SEE mode involving a direct parametric decay of the pump wave into an electrostatic wave (ES) and a secondary EM wave that sometimes could be stronger than the HF pump. SBS has been studied in laboratory plasma experiments by the interaction of high power lasers with plasmas. The SBS instability in magnetized ionospheric plasma was observed for the first time at HAARP in 2010. Our recent work at HAARP has shown that MSBS emission lines can be used to asses electron temperature in the heated region, ion mass spectrometry, determine minor ion species and their densities in the ionosphere, study the physics associated with electron acceleration and artificial airglow. Here, we present new observations of narrowband SEE (NSEE) features at the new mid-latitude heating facility at Arecibo. This includes the direct mode conversion of pump wave through MSBS process. Collected data using ground-based SEE receiver, incoherent scatter radar (ISR), ionospgram, as well as satellite observations will be discussed. The different characteristics of parametric decay instabilities in the high and mid-latitude will be compared. Preliminary theoretical and computational modeling of mid-latitude NSEE will be presented.

Evolution of Photon and Particle Spectra in Compact, Luminous Objects

NASA Technical Reports Server (NTRS)

Eilek, Jean A.; Caroff, Lawrence J.

1995-01-01

Physical conditions in the radiating plasma in the cores of radio-strong quasars and active galactic nuclei cannot be derived from observations until the effects of relativistic aberration are understood. This requires determining both the bulk flow speeds and any wave or signal speed in the parsec-scale nuclear jets. In this project we studied several aspects of such waves. We considered constraints on jet deceleration by mass pickup, and found that bolometric luminosities of the active nuclei cannot constrain core jet speeds usefully. We also simulated observations of ballistic, helical trajectories and helical waves moving directly outwards along the jet. We found that ballistic trajectories are not allowed by the data; the helical features seen are very likely to be helical waves. We believe these are waves propagating in the jet plasma. To this end, we studied waves propagating in relativistic pair plasma jets. In particular, we undertook a program whose goal was to determine the nature of waves which can propagate in relativistic pair plasmas, and how such waves propagating in streaming jet plasma would be observed by an external observer. We developed the possibility of using pulsars as test cases for our models; this takes advantage of new technology in pulsar observations, and the similarity of the physical conditions in the pulsar magnetosphere to the dense, relativistic pair plasmas which exist in radio-strong quasars.

Parametric instabilities of finite-amplitude, circularly polarized Alfven waves in an anisotropic plasma

NASA Technical Reports Server (NTRS)

Hamabata, Hiromitsu

1993-01-01

A class of parametric instabilities of finite-amplitude, circularly polarized Alfven waves in a plasma with pressure anisotropy is studied by application of the CGL equations. A linear perturbation analysis is used to find the dispersion relation governing the instabilities, which is a fifth-order polynomial and is solved numerically. A large-amplitude, circularly polarized wave is unstable with respect to decay into three waves: one sound-like wave and two side-band Alfven-like waves. It is found that, in addition to the decay instability, two new instabilities that are absent in the framework of the MHD equations can occur, depending on the plasma parameters.

Spherical ion acoustic waves in pair ion plasmas with nonthermal electrons

NASA Astrophysics Data System (ADS)

Selim, M. M.

2016-04-01

Propagation of nonplanar ion acoustic waves in a plasma composed of negative and positive ions and nonthermally distributed electrons is investigated using reductive perturbation theory. The spherical Kadomtsev-Petviashvili (SKP) equation which describes the dynamics of the nonlinear spherical ion acoustic waves is derived. It is found that compressive and rarefactive ion-acoustic solitary wave characteristics significantly depend on the density and mass ratios of the positive to negative ions, the nonthermal electron parameter, and the geometry factor. The possible regions for the existence of spherical ion acoustic waves are defined precisely for typical parameters of (H+, O2 -) and (H+, H-) plasmas in the D and F-regions of the Earth's ionosphere, as well as for laboratory plasma (Ar+, F-).

Nonlinear extraordinary wave in dense plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasovitskiy, V. B., E-mail: krasovit@mail.ru; Turikov, V. A.

2013-10-15

Conditions for the propagation of a slow extraordinary wave in dense magnetized plasma are found. A solution to the set of relativistic hydrodynamic equations and Maxwell’s equations under the plasma resonance conditions, when the phase velocity of the nonlinear wave is equal to the speed of light, is obtained. The deviation of the wave frequency from the resonance frequency is accompanied by nonlinear longitudinal-transverse oscillations. It is shown that, in this case, the solution to the set of self-consistent equations obtained by averaging the initial equations over the period of high-frequency oscillations has the form of an envelope soliton. Themore » possibility of excitation of a nonlinear wave in plasma by an external electromagnetic pulse is confirmed by numerical simulations.« less

Fundamental plasma emission involving ion sound waves

NASA Technical Reports Server (NTRS)

Cairns, Iver H.

1987-01-01

The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.

Resonant-cavity antenna for plasma heating

DOEpatents

Perkins, Jr., Francis W.; Chiu, Shiu-Chu; Parks, Paul; Rawls, John M.

1987-01-01

Disclosed is a resonant coil cavity wave launcher for energizing a plasma immersed in a magnetic field. Energization includes launching fast Alfven waves to excite ion cyclotron frequency resonances in the plasma. The cavity includes inductive and capacitive reactive members spaced no further than one-quarter wavelength from a first wall confinement chamber of the plasma. The cavity wave launcher is energized by connection to a waveguide or transmission line carrying forward power from a remote radio frequency energy source.

Oblique propagation of solitary waves in weakly relativistic magnetized plasma with kappa distributed electrons in the presence of negative ions

NASA Astrophysics Data System (ADS)

Salmanpoor, H.; Sharifian, M.; Gholipour, S.; Borhani Zarandi, M.; Shokri, B.

2018-03-01

The oblique propagation of nonlinear ion acoustic solitary waves (solitons) in magnetized collisionless and weakly relativistic plasma with positive and negative ions and super thermal electrons has been examined by using reduced perturbation method to obtain the Korteweg-de Vries equation that admits an obliquely propagating soliton solution. We have investigated the effects of plasma parameters like negative ion density, electrons temperature, angle between wave vector and magnetic field, ions velocity, and k (spectral index in kappa distribution) on the amplitude and width of solitary waves. It has been found out that four modes exist in our plasma model, but the analysis of the results showed that only two types of ion acoustic modes (fast and slow) exist in the plasma and in special cases only one mode could be propagated. The parameters of plasma for these two modes (or one mode) determine which one is rarefactive and which one is compressive. The main parameter is negative ions density (β) indicating which mode is compressive or rarefactive. The effects of the other plasma parameters on amplitude and width of the ion acoustic solitary waves have been studied. The main conclusion is that the effects of the plasma parameters on amplitude and width of the solitary wave strongly depend on the value of the negative ion density.

Excitation of slow waves in front of an ICRF antenna in a basic plasma experiment

NASA Astrophysics Data System (ADS)

Soni, Kunal; van Compernolle, Bart; Crombe, Kristel; van Eester, Dirk

2017-10-01

Recent results of ICRF experiments at the Large Plasma Device (LAPD) indicate parasitic coupling to the slow wave by the fast wave antenna. Plasma parameters in LAPD are similar to the scrape-off layer of current fusion devices. The machine has a 17 m long, 60 cm diameter magnetized plasma column with typical plasma parameters ne 1012 -1013 cm-3, Te 1 - 10 eV and B0 1000 G. It was found that coupling to the slow mode occurs when the plasma density in front of the antenna is low enough such that the lower hybrid resonance is present in the plasma. The radial density profile is tailored to allow for fast mode propagation in the high density core and slow mode propagation in the low density edge region. Measurements of the wave fields clearly show two distinct modes, one long wavelength m=1 fast wave mode in the core and a short wavelength backward propagating mode in the edge. Perpendicular wave numbers compare favorably to the predicted values. The experiment was done for varying frequencies, ω /Ωi = 25 , 6 and 1.5. Future experiments will investigate the dependence on antenna tilt angle with respect to the magnetic field, with and without Faraday screen. This work is performed at the Basic Plasma Science Facility, sponsored jointly by DOE and NSF.

Studies of waves and instabilities using increased beta, warm ion plasmas in LAPD

NASA Astrophysics Data System (ADS)

Carter, Troy; Dorfman, Seth; Gekelman, Walter; Vincena, Steve; van Compernolle, Bart; Tripathi, Shreekrishna; Pribyl, Pat; Morales, George

2015-11-01

A new plasma source based on a Lanthanum Hexaboride (LAB6) emissive cathode has been developed and installed on the LArge Plasma Device (LAPD) at UCLA. The new source provides a much higher discharge current density (compared to the standard LAPD Barium Oxide source) resulting in a factor of ~ 50 increase in plasma density and a factor of ~ 2 - 3 increase in electron temperature. Due to the increased density the ion-electron energy exchange time is shorter in the new plasma, resulting in warm ions (measured spectroscopically to be ~ 5 - 6 eV, up from <~ 1 eV in the standard source plasma). This increased pressure combined with lowered magnetic field provides access to magnetized plasmas with β up to order unity. Topics under investigation include the physics of Alfvén waves in increased β plasmas (dispersion and kinetic damping on ions), electromagnetic effects and magnetic transport in drift-Alfvén wave turbulence, and the excitation of ion-temperature-anisotropy driven modes such as the mirror and firehose instabilities. The capabilities of the new source will be discussed along with initial experimental resuls on electromagnetic drift-Alfvén wave turbulence and Alfvén wave propagation with increased plasma β. Supported by NSF and DOE.

Eulerian simulations of collisional effects on electrostatic plasma waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezzi, Oreste; Valentini, Francesco; Perrone, Denise

2013-09-15

The problem of collisions in a plasma is a wide subject with a huge historical literature. In fact, the description of realistic plasmas is a tough problem to attack, both from the theoretical and the numerical point of view. In this paper, a Eulerian time-splitting algorithm for the study of the propagation of electrostatic waves in collisional plasmas is presented. Collisions are modeled through one-dimensional operators of the Fokker-Planck type, both in linear and nonlinear forms. The accuracy of the numerical code is discussed by comparing the numerical results to the analytical predictions obtained in some limit cases when tryingmore » to evaluate the effects of collisions in the phenomenon of wave plasma echo and collisional dissipation of Bernstein-Greene-Kruskal waves. Particular attention is devoted to the study of the nonlinear Dougherty collisional operator, recently used to describe the collisional dissipation of electron plasma waves in a pure electron plasma column [M. W. Anderson and T. M. O'Neil, Phys. Plasmas 14, 112110 (2007)]. Finally, for the study of collisional plasmas, a recipe to set the simulation parameters in order to prevent the filamentation problem can be provided, by exploiting the property of velocity diffusion operators to smooth out small velocity scales.« less

Penetration and screening of perpendicularly launched electromagnetic waves through bounded supercritical plasma confined in multicusp magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dey, Indranuj; Bhattacharjee, Sudeep

2011-02-15

The question of electromagnetic wave penetration and screening by a bounded supercritical ({omega}{sub p}>{omega} with {omega}{sub p} and {omega} being the electron-plasma and wave frequencies, respectively) plasma confined in a minimum B multicusp field, for waves launched in the k perpendicular B{sub o} mode, is addressed through experiments and numerical simulations. The scale length of radial plasma nonuniformity (|n{sub e}/({partial_derivative}n{sub e}/{partial_derivative}r)|) and magnetostatic field (B{sub o}) inhomogeneity (|B{sub o}/({partial_derivative}B{sub o}/{partial_derivative}r)|) are much smaller than the free space ({lambda}{sub o}) and guided wavelengths ({lambda}{sub g}). Contrary to predictions of plane wave dispersion theory and the Clemow-Mullaly-Allis (CMA) diagram, for a boundedmore » plasma a finite propagation occurs through the central plasma regions where {alpha}{sub p}{sup 2}={omega}{sub p}{sup 2}/{omega}{sup 2}{>=}1 and {beta}{sub c}{sup 2}={omega}{sub ce}{sup 2}/{omega}{sup 2}<<1({approx}10{sup -4}), with {omega}{sub ce} being the electron cyclotron frequency. Wave screening, as predicted by the plane wave model, does not remain valid due to phase mixing and superposition of reflected waves from the conducting boundary, leading to the formation of electromagnetic standing wave modes. The waves are found to satisfy a modified upper hybrid resonance (UHR) relation in the minimum B field and are damped at the local electron cyclotron resonance (ECR) location.« less

Spatial structures arising along a surface wave produced plasma column: an experimental study

NASA Astrophysics Data System (ADS)

Atanassov, V.; Mateev, E.

2007-04-01

The formation of spatial structures in high-frequency and microwave discharges has been known for several decades. Nevertheless it still raises increased interest, probably due to the variety of the observed phenomena and the lack of adequate and systematic theoretical interpretation. In this paper we present preliminary results on observation of spatial structures appearing along a surface wave sustained plasma column. The experiments have been performed in noble gases (xenon and neon) at low to intermediate pressure and the surface wave has been launched by a surfatron. Under these conditions we have observed and documented: i) appearance of stationary plasma rings; ii) formation of standing-wave striationlike patterns; iii) contraction of the plasma column; iv) plasma column transition into moving plasma balls and filaments. Some of the existing theoretical considerations of these phenomena are reviewed and discussed.

Twisted waves and instabilities in a permeating dusty plasma

NASA Astrophysics Data System (ADS)

Bukhari, S.; Ali, S.; Khan, S. A.; Mendonca, J. T.

2018-04-01

New features of the twisted dusty plasma modes and associated instabilities are investigated in permeating plasmas. Using the Vlasov-Poisson model equations, a generalized dispersion relation is obtained for a Maxwellian distributed plasma to analyse the dust-acoustic and dust-ion-acoustic waves with finite orbital angular momentum (OAM) states. Existence conditions for damping/growth rates are discussed and showed significant modifications in twisted dusty modes as compared to straight propagating dusty modes. Numerically, the instability growth rate, which depends on particle streaming and twist effects in the wave potential, is significantly modified due to the Laguerre-Gaussian profiles. Relevance of the study to wave excitations due to penetration of solar wind into cometary clouds or interstellar dusty plasmas is discussed.

Modulation instability and dissipative rogue waves in ion-beam plasma: Roles of ionization, recombination, and electron attachment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Shimin, E-mail: gsm861@126.com; Mei, Liquan, E-mail: lqmei@mail.xjtu.edu.cn

The amplitude modulation of ion-acoustic waves is investigated in an unmagnetized plasma containing positive ions, negative ions, and electrons obeying a kappa-type distribution that is penetrated by a positive ion beam. By considering dissipative mechanisms, including ionization, negative-positive ion recombination, and electron attachment, we introduce a comprehensive model for the plasma with the effects of sources and sinks. Via reductive perturbation theory, the modified nonlinear Schrödinger equation with a dissipative term is derived to govern the dynamics of the modulated waves. The effect of the plasma parameters on the modulation instability criterion for the modified nonlinear Schrödinger equation is numericallymore » investigated in detail. Within the unstable region, first- and second-order dissipative ion-acoustic rogue waves are present. The effect of the plasma parameters on the characteristics of the dissipative rogue waves is also discussed.« less

Surface plasmon oscillations in a semi-bounded semiconductor plasma

NASA Astrophysics Data System (ADS)

M, SHAHMANSOURI; A, P. MISRA

2018-02-01

We study the dispersion properties of surface plasmon (SP) oscillations in a semi-bounded semiconductor plasma with the effects of the Coulomb exchange (CE) force associated with the spin polarization of electrons and holes as well as the effects of the Fermi degenerate pressure and the quantum Bohm potential. Starting from a quantum hydrodynamic model coupled to the Poisson equation, we derive the general dispersion relation for surface plasma waves. Previous results in this context are recovered. The dispersion properties of the surface waves are analyzed in some particular cases of interest and the relative influence of the quantum forces on these waves are also studied for a nano-sized GaAs semiconductor plasma. It is found that the CE effects significantly modify the behaviors of the SP waves. The present results are applicable to understand the propagation characteristics of surface waves in solid density plasmas.

Harmonic effects on ion-bulk waves and simulation of stimulated ion-bulk-wave scattering in CH plasmas

NASA Astrophysics Data System (ADS)

Feng, Q. S.; Zheng, C. Y.; Liu, Z. J.; Cao, L. H.; Xiao, C. Z.; Wang, Q.; Zhang, H. C.; He, X. T.

2017-08-01

Ion-bulk (IBk) wave, a novel branch with a phase velocity close to the ion’s thermal velocity, discovered by Valentini et al (2011 Plasma Phys. Control. Fusion 53 105017), is recently considered as an important electrostatic activity in solar wind, and thus of great interest to space physics and also inertial confinement fusion. The harmonic effects on IBk waves has been researched by Vlasov simulation for the first time. The condition of excitation of the large-amplitude IBk waves is given. The nature of nonlinear IBk waves in the condition of k< {k}{{lor}}/2 (k lor is the wave number at loss-of-resonance point) is undamped Bernstein-Greene-Kruskal-like waves with harmonic superposition. Only when the wave number k of IBk waves satisfies {k}{{lor}}/2≲ k≤slant {k}{{lor}}, can a large-amplitude and mono-frequency IBk wave be excited. A novel stimulated scattering from IBk modes called stimulated ion-bulk-wave scattering (SIBS) or stimulated Feng scattering (SFS) has been proposed and also verified by Vlasov-Maxwell code. In CH plasmas, in addition to the stimulated Brillouin scattering from multi ion-acoustic waves, there exists SIBS simultaneously. This research gives an insight into the SIBS in the field of laser plasma interaction.

Iterative Addition of Kinetic Effects to Cold Plasma RF Wave Solvers

NASA Astrophysics Data System (ADS)

Green, David; Berry, Lee; RF-SciDAC Collaboration

2017-10-01

The hot nature of fusion plasmas requires a wave vector dependent conductivity tensor for accurate calculation of wave heating and current drive. Traditional methods for calculating the linear, kinetic full-wave plasma response rely on a spectral method such that the wave vector dependent conductivity fits naturally within the numerical method. These methods have seen much success for application to the well-confined core plasma of tokamaks. However, quantitative prediction of high power RF antenna designs for fusion applications has meant a requirement of resolving the geometric details of the antenna and other plasma facing surfaces for which the Fourier spectral method is ill-suited. An approach to enabling the addition of kinetic effects to the more versatile finite-difference and finite-element cold-plasma full-wave solvers was presented by where an operator-split iterative method was outlined. Here we expand on this approach, examine convergence and present a simplified kinetic current estimator for rapidly updating the right-hand side of the wave equation with kinetic corrections. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.

Effect of magnetic quantization on ion acoustic waves ultra-relativistic dense plasma

NASA Astrophysics Data System (ADS)

Javed, Asif; Rasheed, A.; Jamil, M.; Siddique, M.; Tsintsadze, N. L.

2017-11-01

In this paper, we have studied the influence of magnetic quantization of orbital motion of the electrons on the profile of linear and nonlinear ion-acoustic waves, which are propagating in the ultra-relativistic dense magneto quantum plasmas. We have employed both Thomas Fermi and Quantum Magneto Hydrodynamic models (along with the Poisson equation) of quantum plasmas. To investigate the large amplitude nonlinear structure of the acoustic wave, Sagdeev-Pseudo-Potential approach has been adopted. The numerical analysis of the linear dispersion relation and the nonlinear acoustic waves has been presented by drawing their graphs that highlight the effects of plasma parameters on these waves in both the linear and the nonlinear regimes. It has been noticed that only supersonic ion acoustic solitary waves can be excited in the above mentioned quantum plasma even when the value of the critical Mach number is less than unity. Both width and depth of Sagdeev potential reduces on increasing the magnetic quantization parameter η. Whereas the amplitude of the ion acoustic soliton reduces on increasing η, its width appears to be directly proportional to η. The present work would be helpful to understand the excitation of nonlinear ion-acoustic waves in the dense astrophysical environments such as magnetars and in intense-laser plasma interactions.

Spatial nonlinear absorption of Alfven waves by dissipative plasma taking account bremsstrahlung

NASA Astrophysics Data System (ADS)

Taiurskii, A. A.; Gavrikov, M. B.

2016-10-01

We study numerically the nonlinear absorption of a plane Alfven wave falling on the stationary boundary of dissipative plasma. This absorption is caused by such factors as the magnetic viscosity, hydrodynamic viscosity, and thermal conductivity of electrons and ions, bremsstrahlung and energy exchange between plasma components. The relevance of this investigation is due to some works, published in 2011, with regard to the heating mechanism of the solar corona and solar wind generation as a result of the absorption of plasma Alfven waves generated in the lower significantly colder layers of the Sun. Numerical analysis shows that the absorption of Alfven waves occurs at wavelengths of the order of skin depth, in which case the classical MHD equations are inapplicable. Therefore, our research is based on equations of two-fluid magnetohydrodynamics that take into account the inertia of the electrons. The implicit difference scheme proposed here for calculating plane-parallel flows of two-fluid plasma reveals a number of important patterns of absorption and thus allows us to study the dependence of the absorption on the Alfven wave frequency and the electron thermal conductivity and viscosity, as well as to evaluate the depth and the velocity of plasma heating during the penetration of Alfven waves interacting with dissipative plasma.

Four Decades of Space-Borne Radio Sounding

NASA Technical Reports Server (NTRS)

Benson, Robert F.

2010-01-01

A review is given of the 38 rocket, satellite, and planetary payloads dedicated to ionospheric/magnetospheric radio sounding since 1961. Between 1961 and 1995, eleven sounding-rocket payloads from four countries evolved from proof-of-concept flights to sophisticated instruments. Some involved dual payloads, with the sounder transmitter on one and the sounder receiver on the other. The rocket sounders addressed specific space-plasma-wave questions, and provided improved measurements of ionospheric electron-density (N(sub e)) field-aligned irregularities (FAI). Four countries launched 12 ionospheric topside-sounder satellites between 1962 and 1994, and an ionospheric sounder was placed on the Mir Space Station in 1998. Eleven magnetospheric radio sounders, most of the relaxation type, were launched from 1977 to 2000. The relaxation sounders used low-power transmitters, designed to stimulate plasma resonances for accurate local Ne determinations. The latest magnetospheric sounder designed for remote sensing incorporated long antennas and digital signal processing techniques to overcome the challenges posed by low Ne values and large propagation distances. Three radio sounders from three countries were included on payloads to extraterrestrial destinations from 1990 to 2003. The scientific accomplishments of space-borne radio sounders included (1) a wealth of global N(sub e) information on the topside ionosphere and magnetosphere, based on vertical and magnetic-field-aligned N(sub e) profiles; (2) accurate in-situ N(sub e) values, even under low-density conditions; and (3) fundamental advances in our understanding of the excitation and propagation of plasma waves, which have even led to the prediction of a new plasma-wave mode.

Dichromatic Langmuir waves in degenerate quantum plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubinov, A. E., E-mail: dubinov-ae@yandex.ru; Kitayev, I. N.

2015-06-15

Langmuir waves in fully degenerate quantum plasma are considered. It is shown that, in the linear approximation, Langmuir waves are always dichromatic. The low-frequency component of the waves corresponds to classical Langmuir waves, while the high-frequency component, to free-electron quantum oscillations. The nonlinear problem on the profile of dichromatic Langmuir waves is solved. Solutions in the form of a superposition of waves and in the form of beatings of its components are obtained.

Wave induced supersonic rotation in mirrors

NASA Astrophysics Data System (ADS)

Fetterman, Abraham

2010-11-01

Wave-particle interactions in ExB supersonically rotating plasmas feature an unusual effect: particles are diffused by waves in both potential energy and kinetic energy [1]. This wave-particle interaction generalizes the alpha channeling effect, in which radio frequency waves are used to remove alpha particles collisionlessly at low energy. In rotating plasmas, the alpha particles may be removed at low energy through the loss cone, and the energy lost may be transferred to the radial electric field. This eliminates the need for electrodes in the mirror throat, which have presented serious technical issues in past rotating plasma devices. A particularly simple way to achieve this effect is to use a high azimuthal mode number perturbation on the magnetic field [2]. In the rotating frame, this perturbation is seen as a wave near the alpha particle cyclotron harmonic, and can break the azimuthal symmetry and magnetic moment conservation without changing the particle's total energy. The particle may exit if it reduces its kinetic energy and becomes more trapped if it gains kinetic energy, leading to a steady state current that maintains the field. Simulations of single particles in rotating mirrors show that a stationary wave can extract enough energy from alpha particles for a reactor to be self-sustaining. Rotation can also be sustained by waves in plasmas without a kinetic energy source. This type of wave has been considered for plasma centrifuges used for isotope separation [3]. [4pt] [1] A. J. Fetterman and N. J. Fisch, Phys Rev Lett 101, 205003 (2008). [0pt] [2] A. J. Fetterman and N. J. Fisch, Phys. Plasmas 17, 042112 (2010). [0pt] [3] A. J. Fetterman and N. J. Fisch, Plasma Sources Sci. Tech. 18, 045003 (2009).

The Basic Plasma Science Facility: a platform for studying plasma processes relevant to space and astrophysical settings

NASA Astrophysics Data System (ADS)

Carter, T. A.

2017-10-01

The Basic Plasma Science Facility at UCLA is a national user facility for studies of fundamental processes in magnetized plasmas. The centerpiece is the Large Plasma Device, a 20 m, magnetized linear plasma device. Two hot cathode plasma sources are available. A Barium Oxide coated cathode produces plasmas with n 1012 cm-3, Te 5 eV, Ti < 1 eV with magnetic field from 400G-2kG. This low- β plasma has been used to study fundamental processes, including: dispersion and damping of kinetic and inertial Alfvén waves, flux ropes and magnetic reconnection, three-wave interactions and parametric instabilities of Alfvén waves, turbulence and transport, and interactions of energetic ions and electrons with plasma waves. A new Lanthanum Hexaboride (LaB6) cathode is now available which produces significantly higher densities and temperatures: n < 5 ×1013 cm-3, Te 12 eV, Ti 6 eV. This higher pressure plasma source enabled the observation of laser-driven collisionless magnetized shocks and, with lowered magnetic field, provides magnetized plasmas with β approaching or possibly exceeding unity. This opens up opportunities for investigating processes relevant to the solar wind and astrophysical plasmas. BaPSF is jointly supported by US DOE and NSF.

Ion acoustic wave assisted laser beat wave terahertz generation in a plasma channel

NASA Astrophysics Data System (ADS)

Tyagi, Yachna; Tripathi, Deepak; Walia, Keshav; Garg, Deepak

2018-04-01

Resonant excitation of terahertz (THz) radiation by non-linear mixing of two lasers in the presence of an electrostatic wave is investigated. The electrostatic wave assists in k matching and contributes to non-linear coupling. In this plasma channel, the electron plasma frequency becomes minimum on the axis. The beat frequency ponderomotive force imparts an oscillating velocity to the electrons. In the presence of an ion-acoustic wave, density perturbation due to the ion-acoustic wave couples with the oscillating velocity of the electrons and give rise to non-linear current that gives rise to an ion-acoustic wave frequency assisted THz radiation field. The normalized field amplitude of ion acoustic wave assisted THz varies inversely for ω/ωp . The field amplitude of ion acoustic wave assisted THz decreases as ω/ωp increases.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Woo-Pyo; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180–3590

The influence of electron spin-interaction on the propagation of the electrostatic space-charge quantum wave is investigated in a cylindrically bounded quantum plasma. The dispersion relation of the space-charge quantum electrostatic wave is derived including the influence of the electron spin-current in a cylindrical waveguide. It is found that the influence of electron spin-interaction enhances the wave frequency for large wave number regions. It is shown that the wave frequencies with higher-solution modes are always smaller than those with lower-solution modes in small wave number domains. In addition, it is found that the wave frequency increases with an increase of themore » radius of the plasma cylinder as well as the Fermi wave number. We discuss the effects due to the quantum and geometric on the variation of the dispersion properties of the space-charge plasma wave.« less

Whistler mode waves in the Jovian magnetosheath

NASA Technical Reports Server (NTRS)

Lin, Naiguo; Kellogg, P. J.; Thiessen, J. P.; Lengyel-Frey, D.; Tsurutani, B. T.; Phillips, J. L.

1994-01-01

During the Ulysses flyby of Jupiter in February 1992, the spacecraft traversed the Jovian magnetosheath for a few hours during the inbound pass and for aa few days during the outbound pass. Burstlike electomagnetic waves at frequencies of approximately 0.1-0.4 of the local electron cyclotron frequency have been observed by the Unified Radio and Plasma Wave (URAP) experiement. The waves were more often observed in the regions which were probably the outer or the middle magnetosheath, especially near the bow shock, and rarely seen in the magnetosphere/magnetosheath boundary layer. The propagation angles of the waves are estimated by comparing the measurements of the wave electric and magnetic fields in the spacecraft spin plane with the corresponding values calculated using the cold plasma dispersion relation under local field and plasma conditions. It is found that the waves propagate obliquely with wave angles between approximately 30 deg and 50 deg. These waves are likely to be the whistler mode waves which are excited by suprathermal electrons with a few hundred eV and a slight anisotropy (T(sub perp)/T(sub parallel) approximately 1.1-1.5). They are probably similar in nature to the lion roars observed in the Earth's magnetosheath. Signature of coupling between the mirror and the whistler mode have also been observed. The plasma conditions which favor the excitation of the whistler mode instability during the wave events exists as observed by the plasma experiement of Ulysses.

Fine Spectral Properties of Langmuir Waves Observed Upstream of the Saturn's Bowshock by the Cassini Wideband Receiver

NASA Astrophysics Data System (ADS)

Hospodarsky, G. B.; Pisa, D.; Santolik, O.; Kurth, W. S.; Soucek, J.; Basovnik, M.; Gurnett, D. A.; Arridge, C. S.

2015-12-01

Langmuir waves are commonly observed in the upstream regions of planetary and interplanetary shock. Solar wind electrons accelerated at the shock front are reflected back into the solar wind and can form electron beams. In regions with beams, the electron distribution becomes unstable and electrostatic waves can be generated. The process of generation and the evolution of electrostatic waves strongly depends on the solar wind electron distribution and generally exhibits complex behavior. Langmuir waves can be identified as intense narrowband emission at a frequency very close to the local plasma frequency and weaker broadband waves below and above the plasma frequency deeper in the downstream region. We present a detailed study of Langmuir waves detected upstream of the Saturnian bowshock by the Cassini spacecraft. Using data from the Radio and Plasma Wave Science (RPWS), Magnetometer (MAG) and Cassini Plasma Spectrometer (CAPS) instruments we have analyzed several periods containing the extended waveform captures by the Wideband Receiver. Langmuir waves are a bursty emission highly controlled by variations in solar wind conditions. Unfortunately due to a combination of instrumental field of view and sampling period, it is often difficult to identify the electron distribution function that is unstable and able to generate Langmuir waves. We used an electrostatic version of particle-in-cell simulation of the Langmuir wave generation process to reproduce some of the more subtle observed spectral features and help understand the late stages of the instability and interactions in the solar wind plasma.

Non-linear Frequency Shifts, Mode Couplings, and Decay Instability of Plasma Waves

NASA Astrophysics Data System (ADS)

Affolter, Mathew; Anderegg, F.; Driscoll, C. F.; Valentini, F.

2015-11-01

We present experiments and theory for non-linear plasma wave decay to longer wavelengths, in both the oscillatory coupling and exponential decay regimes. The experiments are conducted on non-neutral plasmas in cylindrical Penning-Malmberg traps, θ-symmetric standing plasma waves have near acoustic dispersion ω (kz) ~kz - αkz2 , discretized by kz =mz (π /Lp) . Large amplitude waves exhibit non-linear frequency shifts δf / f ~A2 and Fourier harmonic content, both of which are increased as the plasma dispersion is reduced. Non-linear coupling rates are measured between large amplitude mz = 2 waves and small amplitude mz = 1 waves, which have a small detuning Δω = 2ω1 -ω2 . At small excitation amplitudes, this detuning causes the mz = 1 mode amplitude to ``bounce'' at rate Δω , with amplitude excursions ΔA1 ~ δn2 /n0 consistent with cold fluid theory and Vlasov simulations. At larger excitation amplitudes, where the non-linear coupling exceeds the dispersion, phase-locked exponential growth of the mz = 1 mode is observed, in qualitative agreement with simple 3-wave instability theory. However, significant variations are observed experimentally, and N-wave theory gives stunningly divergent predictions that depend sensitively on the dispersion-moderated harmonic content. Measurements on higher temperature Langmuir waves and the unusual ``EAW'' (KEEN) waves are being conducted to investigate the effects of wave-particle kinetics on the non-linear coupling rates. Department of Energy Grants DE-SC0002451and DE-SC0008693.

Processing and interpretation of experiments in the microwave interferometry of shock waves in a weakly ionized plasma

NASA Astrophysics Data System (ADS)

Ershov, A. P.; Klishin, S. V.; Kuzovnikov, S. V.; Ponomareva, S. E.; Pyt'ev, Iu. P.

1990-12-01

The reduction method is applied to the microwave interferometry of shock waves in a weakly ionized plasma, making it possible to improve the spatial resolution of the instrument. It is shown experimentally that the structure of the shock wave electron component in a high-frequency discharge plasma in atomic and molecular gases is characterized by the presence of a precursor in the form of a rarefaction wave. The origin of the precursor is examined.

Plasma waves produced by the xenon ion beam experiment on the Porcupine sounding rocket

NASA Technical Reports Server (NTRS)

Kintner, P. M.; Kelley, M.

1982-01-01

The production of electrostatic ion cyclotron waves by a perpendicular ion beam in the F-region ionosphere is described. The ion beam experiment was part of the Porcupine program and produced electrostatic hydrogen cyclotron waves just above harmonics of the hydrogen cyclotron frequency. The plasma process may be thought of as a magnetized background ionosphere through which an unmagnetized beam is flowing. The dispersion equation for this hypothesis is constructed and solved. Preliminary solutions agree well with the observed plasma waves.

Simultaneous Measurements of Substorm-Related Electron Energization in the Ionosphere and the Plasma Sheet

NASA Astrophysics Data System (ADS)

Sivadas, N.; Semeter, J.; Nishimura, Y.; Kero, A.

2017-10-01

On 26 March 2008, simultaneous measurements of a large substorm were made using the Poker Flat Incoherent Scatter Radar, Time History of Events and Macroscale Interactions during Substorm (THEMIS) spacecraft, and all sky cameras. After the onset, electron precipitation reached energies ≳100 keV leading to intense D region ionization. Identifying the source of energetic precipitation has been a challenge because of lack of quantitative and magnetically conjugate measurements of loss cone electrons. In this study, we use the maximum entropy inversion technique to invert altitude profiles of ionization measured by the radar to estimate the loss cone energy spectra of primary electrons. By comparing them with magnetically conjugate measurements from THEMIS-D spacecraft in the nightside plasma sheet, we constrain the source location and acceleration mechanism of precipitating electrons of different energy ranges. Our analysis suggests that the observed electrons ≳100 keV are a result of pitch angle scattering of electrons originating from or tailward of the inner plasma sheet at 9RE, possibly through interaction with electromagnetic ion cyclotron waves. The electrons of energy 10-100 keV are produced by pitch angle scattering due to a potential drop of ≲10 kV in the auroral acceleration region (AAR) as well as wave-particle interactions in and tailward of the AAR. This work demonstrates the utility of magnetically conjugate ground- and space-based measurements in constraining the source of energetic electron precipitation. Unlike in situ spacecraft measurements, ground-based incoherent scatter radars combined with an appropriate inversion technique can be used to provide remote and continuous-time estimates of loss cone electrons in the plasma sheet.

Parametric decay of oblique Alfvén waves in two-dimensional hybrid simulations.

PubMed

Verscharen, D; Marsch, E; Motschmann, U; Müller, J

2012-08-01

Certain types of plasma waves are known to become parametrically unstable under specific plasma conditions, in which the pump wave will decay into several daughter waves with different wavenumbers and frequencies. In the past, the related plasma instabilities have been treated analytically for various parameter regimes and by use of various numerical methods, yet the oblique propagation with respect to the background magnetic field has rarely been dealt with in two dimensions, mainly because of the high computational demand. Here we present a hybrid-simulation study of the parametric decay of a moderately oblique Alfvén wave having elliptical polarization. It is found that such a compressive wave can decay into waves with higher and lower wavenumbers than the pump.

Wave propagation in a quasi-chemical equilibrium plasma

NASA Technical Reports Server (NTRS)

Fang, T.-M.; Baum, H. R.

1975-01-01

Wave propagation in a quasi-chemical equilibrium plasma is studied. The plasma is infinite and without external fields. The chemical reactions are assumed to result from the ionization and recombination processes. When the gas is near equilibrium, the dominant role describing the evolution of a reacting plasma is played by the global conservation equations. These equations are first derived and then used to study the small amplitude wave motion for a near-equilibrium situation. Nontrivial damping effects have been obtained by including the conduction current terms.

Effect of wave localization on plasma instabilities

NASA Astrophysics Data System (ADS)

Levedahl, William Kirk

1987-10-01

The Anderson model of wave localization in random media is involved to study the effect of solar wind density turbulence on plasma processes associated with the solar type III radio burst. ISEE-3 satellite data indicate that a possible model for the type III process is the parametric decay of Langmuir waves excited by solar flare electron streams into daughter electromagnetic and ion acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Reigel criteria for wave localization in the solar wind with observed density fluctuations -1 percent. Numerical simulations of wave propagation in random media confirm the localization length predictions of Escande and Souillard for stationary density fluctations. For mobile density fluctuations localized wave packets spread at the propagation velocity of the density fluctuations rather than the group velocity of the waves. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action principle approach is used to develop a theory of non-linear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability. It is argued that localization of electromagnetic waves will allow the instability threshold to be exceeded for the parametric decay discussed above.

The ISPM unified radio and plasma wave experiment

NASA Technical Reports Server (NTRS)

Stone, R. G.; Caldwell, J.; Deconchy, Y.; Deschanciaux, C.; Ebbett, R.; Epstein, G.; Groetz, K.; Harvey, C. C.; Hoang, S.; Howard, R.

1983-01-01

Hardware for the International Solar Polar Mission (ISPM) Unified Radio and Plasma (URAP) wave experiment is presented. The URAP determines direction and polarization of distant radio sources for remote sensing of the heliosphere, and studies local wave phenomena which determine the transport coefficients of the ambient plasma. Electric and magnetic field antennas and preamplifiers; the electromagnetic compatibility plan and grounding; radio astronomy and plasma frequency receivers; a fast Fourier transformation data processing unit waveform analyzer; dc voltage measurements; a fast envelope sampler for the solar wind, and plasmas near Jupiter; a sounder; and a power converter are described.

The Plasma Wave Experiment (PWE) on board the Arase (ERG) satellite

NASA Astrophysics Data System (ADS)

Kasahara, Yoshiya; Kasaba, Yasumasa; Kojima, Hirotsugu; Yagitani, Satoshi; Ishisaka, Keigo; Kumamoto, Atsushi; Tsuchiya, Fuminori; Ozaki, Mitsunori; Matsuda, Shoya; Imachi, Tomohiko; Miyoshi, Yoshizumi; Hikishima, Mitsuru; Katoh, Yuto; Ota, Mamoru; Shoji, Masafumi; Matsuoka, Ayako; Shinohara, Iku

2018-05-01

The Exploration of energization and Radiation in Geospace (ERG) project aims to study acceleration and loss mechanisms of relativistic electrons around the Earth. The Arase (ERG) satellite was launched on December 20, 2016, to explore in the heart of the Earth's radiation belt. In the present paper, we introduce the specifications of the Plasma Wave Experiment (PWE) on board the Arase satellite. In the inner magnetosphere, plasma waves, such as the whistler-mode chorus, electromagnetic ion cyclotron wave, and magnetosonic wave, are expected to interact with particles over a wide energy range and contribute to high-energy particle loss and/or acceleration processes. Thermal plasma density is another key parameter because it controls the dispersion relation of plasma waves, which affects wave-particle interaction conditions and wave propagation characteristics. The DC electric field also plays an important role in controlling the global dynamics of the inner magnetosphere. The PWE, which consists of an orthogonal electric field sensor (WPT; wire probe antenna), a triaxial magnetic sensor (MSC; magnetic search coil), and receivers named electric field detector (EFD), waveform capture and onboard frequency analyzer (WFC/OFA), and high-frequency analyzer (HFA), was developed to measure the DC electric field and plasma waves in the inner magnetosphere. Using these sensors and receivers, the PWE covers a wide frequency range from DC to 10 MHz for electric fields and from a few Hz to 100 kHz for magnetic fields. We produce continuous ELF/VLF/HF range wave spectra and ELF range waveforms for 24 h each day. We also produce spectral matrices as continuous data for wave direction finding. In addition, we intermittently produce two types of waveform burst data, "chorus burst" and "EMIC burst." We also input raw waveform data into the software-type wave-particle interaction analyzer (S-WPIA), which derives direct correlation between waves and particles. Finally, we introduce our PWE observation strategy and provide some initial results.[Figure not available: see fulltext.

Nonlinear interaction of an intense radio wave with ionospheric D/E layer plasma

NASA Astrophysics Data System (ADS)

Sodha, Mahendra Singh; Agarwal, Sujeet Kumar

2018-05-01

This paper considers the nonlinear interaction of an intense electromagnetic wave with the D/E layer plasma in the ionosphere. A simultaneous solution of the electromagnetic wave equation and the equations describing the kinetics of D/E layer plasma is obtained; the phenomenon of ohmic heating of electrons by the electric field of the wave causes enhanced collision frequency and ionization of neutral species. Electron temperature dependent recombination of electrons with ions, electron attachment to O 2 molecules, and detachment of electrons from O2 - ions has also been taken into account. The dependence of the plasma parameters on the square of the electric vector of the wave E0 2 has been evaluated for three ionospheric heights (viz., 90, 100, and 110 km) corresponding to the mid-latitude mid-day ionosphere and discussed; these results are used to investigate the horizontal propagation of an intense radio wave at these heights.

Backward propagating branch of surface waves in a semi-bounded streaming plasma system

NASA Astrophysics Data System (ADS)

Lim, Young Kyung; Lee, Myoung-Jae; Seo, Ki Wan; Jung, Young-Dae

2017-06-01

The influence of wake and magnetic field on the surface ion-cyclotron wave is kinetically investigated in a semi-bounded streaming dusty magnetoplasma in the presence of the ion wake-field. The analytic expressions of the frequency and the group velocity are derived by the plasma dielectric function with the spectral reflection condition. The result shows that the ion wake-field enhances the wave frequency and the group velocity of the surface ion-cyclotron wave in a semi-bounded dusty plasma. It is found that the frequency and the group velocity of the surface electrostatic-ion-cyclotron wave increase with an increase of the strength of the magnetic field. It is interesting to find out that the group velocity without the ion flow has the backward propagation mode in a semi-bounded dusty plasma. The variations due to the frequency and the group velocity of the surface ion-cyclotron wave are also discussed.

Linear and nonlinear dynamics of current-driven waves in dusty plasmas

NASA Astrophysics Data System (ADS)

Ahmad, Ali; Ali Shan, S.; Haque, Q.; Saleem, H.

2012-09-01

The linear and nonlinear dynamics of a recently proposed plasma mode of dusty plasma is studied using kappa distribution for electrons. This electrostatic wave can propagate in the plasma due to the sheared flow of electrons and ions parallel to the external magnetic field in the presence of stationary dust. The coupling of this wave with the usual drift wave and ion acoustic wave is investigated. D'Angelo's mode is also modified in the presence of superthermal electrons. In the nonlinear regime, the wave can give rise to dipolar vortex structures if the shear in flow is weaker and tripolar vortices if the flow has steeper gradient. The results have been applied to Saturn's magnetosphere corresponding to negatively charged dust grains. But the theoretical model is applicable for positively charged dust as well. This work will be useful for future observations and studies of dusty environments of planets and comets.

Propagation of Electron Acoustic Soliton, Periodic and Shock Waves in Dissipative Plasma with a q-Nonextensive Electron Velocity Distribution

NASA Astrophysics Data System (ADS)

El-Hanbaly, A. M.; El-Shewy, E. K.; Elgarayhi, A.; Kassem, A. I.

2015-11-01

The nonlinear properties of small amplitude electron-acoustic (EA) solitary and shock waves in a homogeneous system of unmagnetized collisionless plasma with nonextensive distribution for hot electrons have been investigated. A reductive perturbation method used to obtain the Kadomstev-Petviashvili-Burgers equation. Bifurcation analysis has been discussed for non-dissipative system in the absence of Burgers term and reveals different classes of the traveling wave solutions. The obtained solutions are related to periodic and soliton waves and their behavior are shown graphically. In the presence of the Burgers term, the EXP-function method is used to solve the Kadomstev-Petviashvili-Burgers equation and the obtained solution is related to shock wave. The obtained results may be helpful in better conception of waves propagation in various space plasma environments as well as in inertial confinement fusion laboratory plasmas.

Collective dynamics of large aspect ratio dusty plasma in an inhomogeneous plasma background: Formation of the co-rotating vortex series

NASA Astrophysics Data System (ADS)

Choudhary, Mangilal; Mukherjee, S.; Bandyopadhyay, P.

2018-02-01

In this paper, the collective dynamics of large aspect ratio dusty plasma is studied over a wide range of discharge parameters. An inductively coupled diffused plasma, which creates an electrostatic trap to confine the negatively charged grains, is used to form a large volume (or large aspect ratio) dusty plasma at low pressure. For introducing the dust grains into the potential well, a unique technique using secondary DC glow discharge plasma is employed. The dust dynamics is recorded in a two-dimension (2D) plane at a given axial location. The dust fluid exhibits wave-like behavior at low pressure (p < 0.06 mbar) and high rf power (P > 3 W). The mixed motion, waves and vortices, is observed at an intermediate gas pressure (p ˜ 0.08 mbar) and low power (P < 3 W). Above the threshold value of gas pressure (p > 0.1 mbar), the clockwise and anti-clockwise co-rotating vortex series are observed on edges of the dust cloud, whereas the particles in the central region show random motion. These vortices are only observed above the threshold width of the dust cloud. The occurrence of the co-rotating vortices is understood on the basis of the charge gradient of dust particles, which is orthogonal to the gravity. The charge gradient is a consequence of the plasma inhomogeneity from the central region to the outer edge of the dust fluid. Since a vortex has the characteristic size in the dissipative medium; therefore, a series of the co-rotating vortex on both sides of dusty plasma is observed. The experimental results on the vortex formation and its multiplicity are compared to an available theoretical model and are found to be in close agreement.

Method for plasma formation for extreme ultraviolet lithography-theta pinch

DOEpatents

Hassanein, Ahmed [Naperville, IL; Konkashbaev, Isak [Bolingbrook, IL; Rice, Bryan [Hillsboro, OR

2007-02-20

A device and method for generating extremely short-wave ultraviolet electromagnetic wave, utilizing a theta pinch plasma generator to produce electromagnetic radiation in the range of 10 to 20 nm. The device comprises an axially aligned open-ended pinch chamber defining a plasma zone adapted to contain a plasma generating gas within the plasma zone; a means for generating a magnetic field radially outward of the open-ended pinch chamber to produce a discharge plasma from the plasma generating gas, thereby producing a electromagnetic wave in the extreme ultraviolet range; a collecting means in optical communication with the pinch chamber to collect the electromagnetic radiation; and focusing means in optical communication with the collecting means to concentrate the electromagnetic radiation.

Current drive at plasma densities required for thermonuclear reactors.

PubMed

Cesario, R; Amicucci, L; Cardinali, A; Castaldo, C; Marinucci, M; Panaccione, L; Santini, F; Tudisco, O; Apicella, M L; Calabrò, G; Cianfarani, C; Frigione, D; Galli, A; Mazzitelli, G; Mazzotta, C; Pericoli, V; Schettini, G; Tuccillo, A A

2010-08-10

Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors.

Electromagnetic resonances of plasma column between two metallic plates

NASA Astrophysics Data System (ADS)

Dvinin, Sergey; Dovzhenko, Vitaly; Sinkevich, Oleg

2015-09-01

It is known that there are two types of electrodynamic resonances of bounded supercritical plasma, placed between the two metal planes are possible. The first type is associated with the excitation of surface waves propagating along the lateral surface. The second one is caused by standing surface waves in the sheath at plasma-metal boundary. This work is concerned with theoretical study of the resonance properties of plasma slab in cases where both effects can be observed together. Resonance densities and frequencies are calculated. Solution of Maxwell's equations is demonstrated that directions of energy flows in first and second cases are opposite. Energy transfer to lateral surface waves is prevailing, if the field frequency is higher than the frequency, corresponding to the geometric plasma-sheath resonance. Amplitude of waves at plasma metal boundary becomes greater in opposite case. Discharge properties in both cases are calculated including joint excitation.

Rarefaction waves, solitons, and holes in a pure electron plasma

NASA Astrophysics Data System (ADS)

Moody, J. D.; Driscoll, C. F.

1995-12-01

The propagation of holes, solitons, and rarefaction waves along the axis of a magnetized pure electron plasma column is described. The time dependence of the radially averaged density perturbation produced by the nonlinear waves is measured at several locations along the plasma column for a wide range of plasma parameters. The rarefaction waves are studied by measuring the free expansion of the plasma into a vacuum. A new hydrodynamic theory is described that quantitatively predicts the free expansion measurements. The rarefaction is initially characterized by a self-similar plasma flow, resulting in a perturbed density and velocity without a characteristic length scale. The electron solitons show a small increase in propagation speed with increasing amplitude and exhibit electron bursts. The holes show a decrease in propagation speed with increasing amplitude. Collisions between holes and solitons show that these objects pass through each other undisturbed, except for a small offset.

Magnetosonic shock wave in collisional pair-ion plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adak, Ashish, E-mail: ashish-adak@yahoo.com; Khan, Manoranjan, E-mail: mkhan.ju@gmail.com; Sikdar, Arnab, E-mail: arnabs.ju@gmail.com

2016-06-15

Nonlinear propagation of magnetosonic shock wave has been studied in collisional magnetized pair-ion plasma. The masses of both ions are same but the temperatures are slightly different. Two fluid model has been taken to describe the model. Two different modes of the magnetosonic wave have been obtained. The dynamics of the nonlinear magnetosonic wave is governed by the Korteweg-de Vries Burgers' equation. It has been shown that the ion-ion collision is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The numerical investigations reveal that the magnetosonic wavemore » exhibits both oscillatory and monotonic shock structures depending on the strength of the dissipation. The nonlinear wave exhibited the oscillatory shock wave for strong magnetic field (weak dissipation) and monotonic shock wave for weak magnetic field (strong dissipation). The results have been discussed in the context of the fullerene pair-ion plasma experiments.« less

Excitation of Plasma Waves in Aurora by Electron Beams

NASA Technical Reports Server (NTRS)

daSilva, C. E.; Vinas, A. F.; deAssis, A. S.; deAzevedo, C. A.

1996-01-01

In this paper, we study numerically the excitation of plasma waves by electron beams, in the auroral region above 2000 km of altitude. We have solved the fully kinetic dispersion relation, using numerical method and found the real frequency and the growth rate of the plasma wave modes. We have examined the instability properties of low-frequency waves such as the Electromagnetic Ion Cyclotron (EMIC) wave as well as Lower-Hybrid (LH) wave in the range of high-frequency. In all cases, the source of free energy are electron beams propagating parallel to the geomagnetic field. We present some features of the growth rate modes, when the cold plasma parameters are changed, such as background electrons and ions species (H(+) and O(+)) temperature, density or the electron beam density and/or drift velocity. These results can be used in a test-particle simulation code, to investigate the ion acceleration and their implication in the auroral acceleration processes, by wave-particle interaction.

On the instability and energy flux of lower hybrid waves in the Venus plasma mantle

NASA Technical Reports Server (NTRS)

Strangeway, R. J.; Crawford, G. K.

1993-01-01

Waves generated near the lower hybrid resonance frequency by the modified two stream instability have been invoked as a possible source of energy flux into the topside ionosphere of Venus. These waves are observed above the ionopause in a region known as the plasma mantle. The plasma within the mantle appears to be a mixture of magnetosheath and ionospheric plasmas. Since the magnetosheath electrons and ions have temperatures of several tens of eV, any instability analysis of the modified two stream instability requires the inclusion of finite electron and ion temperatures. Finite temperature effects are likely to reduce the growth rate of the instability. Furthermore, the lower hybrid waves are only quasi-electrostatic, and the energy flux of the waves is mainly carried by parallel Poynting flux. The magnetic field in the mantle is draped over the ionopause. Lower hybrid waves therefore cannot transport any significant wave energy to lower altitudes, and so do not act as a source of additional heat to the topside ionosphere.

The Nonlinear Coupling of Alfven and Lower Hybrid Waves in Space Plasma

NASA Technical Reports Server (NTRS)

Khazanov, George V.

2004-01-01

Space plasmas support a wide variety of waves, and wave-particle interactions as well as wave-wave interactions which are of crucial importance to magnetospheric and ionospheric plasma behavior. The excitation of lower hybrid waves (LHWs) in particular is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves may generate LHWs in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We present several examples of observational data which illustrate that the proposed mechanism is a plausible candidate to explain certain classes of LHW generation events in the ionosphere and magnetosphere and demonstrate electron and ion energization involving these processes. We discuss the morphology dynamics and level of LHW activity generated by electromagnetic ion cyclotron (EMIC) waves during the May 2-7 1998 storm period on the global scale. The LHWs were calculated based on a newly developed self-consistent model (Khazanov et. al. 2002) that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic and another equation describes the evolution of EMIC waves. It is found that the LHWs are excited by helium ions due to their mass dependent drift in the electric field of EMIC waves. The level of LHW activity is calculated assuming that the induced scattering process is the main saturation mechanism for these waves. The calculated LHWs electric fields are consistent with the observational data.

The ISEE-1 and ISEE-2 plasma wave investigation

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Scarf, F. L.; Fredricks, R. W.; Smith, E. J.

1978-01-01

The ISEE-1 and ISEE-2 plasma wave experiments are designed to provide basic information on wave-particle interactions in the earth's magnetosphere and in the solar wind. The ISEE-1 plasma wave instrument uses three electric dipole antennas with lengths of 215, 73.5 and 0.61 m for electric field measurements, and a triaxial search coil antenna for magnetic field measurements. The ISEE-2 instrument uses two electric dipole antennas with lengths of 30 and 0.61 m for electric field measurements and a single-axis search coil antenna for magnetic field measurements. The primary scientific objectives of the experiments are described, including the resolution of space-time relationships of plasma wave phenomena and VLBI studies. The instrumentation is described, with emphasis on the antennas and the electronics.

Large-amplitude hydromagnetic waves in collisionless relativistic plasma - Exact solution for the fast-mode magnetoacoustic wave

NASA Technical Reports Server (NTRS)

Barnes, A.

1983-01-01

An exact nonlinear solution is found to the relativistic kinetic and electrodynamic equations (in their hydromagnetic limit) that describes the large-amplitude fast-mode magnetoacoustic wave propagating normal to the magnetic field in a collisionless, previously uniform plasma. It is pointed out that a wave of this kind will be generated by transverse compression of any collisionless plasma. The solution is in essence independent of the detailed form of the particle momentum distribution functions. The solution is obtained, in part, through the method of characteristics; the wave exhibits the familiar properties of steepening and shock formation. A detailed analysis is given of the ultrarelativistic limit of this wave.

Millimeter Wave Communication through Plasma

NASA Technical Reports Server (NTRS)

Bastin, Gary L.

2008-01-01

Millimeter wave communication through plasma at frequencies of 35 GHz or higher shows promise in maintaining communications connectivity during rocket launch and re-entry, critical events which are typically plagued with communication dropouts. Extensive prior research into plasmas has characterized the plasma frequency at these events, and research at the Kennedy Space Center is investigating the feasibility of millimeter communication through these plasma frequencies.

Helicon mysteries: fitting a plane wave into a cylinder

NASA Astrophysics Data System (ADS)

Boswell, Rod

2011-10-01

Since the first reports in the 1960s, the dispersion of helicon waves in a plasma cylinder has been difficult to describe theoretically for axial wavelengths that are greater than the plasma radius. About 10 years ago, Breizman and Arefiev showed how radial density gradients make the plasma column similar to a coaxial cable, allowing the helicon waves to propagate below the cut-off frequency. The resulting dispersion relation is similar to that of a plane wave propagating parallel to the magnetic field. A few years later, Degeling et. al. presented experimental evidence demonstrating such a plane wave dispersion for a broad range of axial wave numbers. The reason lies in the decoupling of the Hall and electron inertial terms in the dispersion, the former describing the electromagnetic propagation and the latter the electrostatic propagation. Combining the experimental and theoretical results has recently thrown further light on this phenomenon that is applicable to both space and laboratory situations. Radially Localized Helicon Modes in Nonuniform Plasma, Boris N. Breizman and Alexey V. Arefiev, Phys. Rev. Letts. 84, 3863 (2000). Transitions from electrostatic to electromagnetic whistler wave excitation, A. W. Degeling, G. G. Borg and R. W. Boswell, Phys. Plasmas, 11, 2144, (2004).

Exploration of high harmonic fast wave heating on the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Wilson, J. R.; Bell, R. E.; Bernabei, S.; Bitter, M.; Bonoli, P.; Gates, D.; Hosea, J.; LeBlanc, B.; Mau, T. K.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C. K.; Pinsker, R. I.; Raman, R.; Rosenberg, A.; Ryan, P.; Sabbagh, S.; Stutman, D.; Swain, D.; Takase, Y.; Wilgen, J.

2003-05-01

High harmonic fast wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, S. Neumeyer et al., in Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999 (IEEE, Piscataway, NJ, 1999), p. 53] is such a device. An rf heating system has been installed on the NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.

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.

The existence of electron-acoustic shock waves and their interactions in a non-Maxwellian plasma with q-nonextensive distributed electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jiu-Ning; He, Yong-Lin; Han, Zhen-Hai

2013-07-15

We present a theoretical investigation for the nonlinear interaction between electron-acoustic shock waves in a nonextensive two-electron plasma. The interaction is governed by a pair of Korteweg-de Vries-Burgers equations. We focus on studying the colliding effects on the propagation of shock waves, more specifically, we have studied the effects of plasma parameters, i.e., the nonextensive parameter q, the “hot” to “cold” electron number density ratio α, and the normalized electron kinematic viscosity η{sub 0} on the trajectory changes (phase shifts) of shock waves. It is found that there are trajectory changes (phase shifts) for both colliding shock waves in themore » present plasma system. We also noted that the nonlinearity has no decisive effect on the trajectory changes, the occurrence of trajectory changes may be due to the combined role played by the dispersion and dissipation of the nonlinear structure. Our theoretical study may be beneficial to understand the propagation and interaction of nonlinear electrostatic waves and may brings a possibility to develop the nonlinear theory of electron-acoustic waves in astrophysical plasma systems.« less

Low-Frequency Waves in Cold Three-Component Plasmas

NASA Astrophysics Data System (ADS)

Fu, Qiang; Tang, Ying; Zhao, Jinsong; Lu, Jianyong

2016-09-01

The dispersion relation and electromagnetic polarization of the plasma waves are comprehensively studied in cold electron, proton, and heavy charged particle plasmas. Three modes are classified as the fast, intermediate, and slow mode waves according to different phase velocities. When plasmas contain positively-charged particles, the fast and intermediate modes can interact at the small propagating angles, whereas the two modes are separate at the large propagating angles. The near-parallel intermediate and slow waves experience the linear polarization, circular polarization, and linear polarization again, with the increasing wave number. The wave number regime corresponding to the above circular polarization shrinks as the propagating angle increases. Moreover, the fast and intermediate modes cause the reverse change of the electromagnetic polarization at the special wave number. While the heavy particles carry the negative charges, the dispersion relations of the fast and intermediate modes are always separate, being independent of the propagating angles. Furthermore, this study gives new expressions of the three resonance frequencies corresponding to the highly-oblique propagation waves in the general three-component plasmas, and shows the dependence of the resonance frequencies on the propagating angle, the concentration of the heavy particle, and the mass ratio among different kinds of particles. supported by National Natural Science Foundation of China (Nos. 11303099, 41531071 and 41574158), and the Youth Innovation Promotion Association CAS

The Effect of Background Plasma Temperature on Growth and Damping of Whistler Mode Wave Power in the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; Malaspina, D.; Jaynes, A. N.

2017-12-01

Whistler mode waves play a dominant role in the energy dynamics of the Earth's magnetosphere. Trajectory of whistler mode waves can be predicted by raytracing. Raytracing is a numerical method which solves the Haselgrove's equations at each time step taking the background plasma parameters in to account. The majority of previous raytracing work was conducted assuming a cold (0 K) background magnetospheric plasma. Here we perform raytracing in a finite temperature plasma with background electron and ion temperatures of a few eV. When encountered with a high energy (>10 keV) electron distribution, whistler mode waves can undergo a power attenuation and/or growth, depending on resonance conditions which are a function of wave frequency, wave normal angle and particle energy. In this work we present the wave power attenuation and growth analysis of whistler mode waves, during the interaction with a high energy electron distribution. We have numerically modelled the high energy electron distribution as an isotropic velocity distribution, as well as an anisotropic bi-Maxwellian distribution. Both cases were analyzed with and without the temperature effects for the background magnetospheric plasma. Finally we compare our results with the whistler mode energy distribution obtained by the EMFISIS instrument hosted at the Van Allen Probe spacecraft.

Electromagnetic radiation accompanying gravitational waves from black hole binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolgov, A.; Postnov, K., E-mail: dolgov@fe.infn.it, E-mail: kpostnov@gmail.com

The transition of powerful gravitational waves, created by the coalescence of massive black hole binaries, into electromagnetic radiation in external magnetic fields is considered. In contrast to the previous calculations of the similar effect we study the realistic case of the gravitational radiation frequency below the plasma frequency of the surrounding medium. The gravitational waves propagating in the plasma constantly create electromagnetic radiation dragging it with them, despite the low frequency. The plasma heating by the unattenuated electromagnetic wave may be significant in hot rarefied plasma with strong magnetic field and can lead to a noticeable burst of electromagnetic radiationmore » with higher frequency. The graviton-to-photon conversion effect in plasma is discussed in the context of possible electromagnetic counterparts of GW150914 and GW170104.« less

Large-Amplitude High-Frequency Waves at Earth's Magnetopause

NASA Astrophysics Data System (ADS)

Graham, D. B.; Vaivads, A.; Khotyaintsev, Yu. V.; André, M.; Le Contel, O.; Malaspina, D. M.; Lindqvist, P.-A.; Wilder, F. D.; Ergun, R. E.; Gershman, D. J.; Giles, B. L.; Magnes, W.; Russell, C. T.; Burch, J. L.; Torbert, R. B.

2018-04-01

Large-amplitude waves near the electron plasma frequency are found by the Magnetospheric Multiscale (MMS) mission near Earth's magnetopause. The waves are identified as Langmuir and upper hybrid (UH) waves, with wave vectors either close to parallel or close to perpendicular to the background magnetic field. The waves are found all along the magnetopause equatorial plane, including both flanks and close to the subsolar point. The waves reach very large amplitudes, up to 1 V m-1, and are thus among the most intense electric fields observed at Earth's magnetopause. In the magnetosphere and on the magnetospheric side of the magnetopause the waves are predominantly UH waves although Langmuir waves are also found. When the plasma is very weakly magnetized only Langmuir waves are likely to be found. Both Langmuir and UH waves are shown to have electromagnetic components, which are consistent with predictions from kinetic wave theory. These results show that the magnetopause and magnetosphere are often unstable to intense wave activity near the electron plasma frequency. These waves provide a possible source of radio emission at the magnetopause.

Properties of ultra low frequency upstream waves at Venus and Saturn: A comparison

NASA Technical Reports Server (NTRS)

Orlowski, D. S.; Russell, C. T.; Krauss-Varban, D.; Omidi, N.

1995-01-01

The upstream regions of all planets, except Pluto, have been investigated, using in situ spacecraft measurements and a variety of analysis techniques. The detailed studies at Earth indicate that these waves are generated locally in the magnetically connected solar wind by the interaction with ions backstreaming from the shock. However, since the properties of the solar wind vary with heliocentric distance and since properties of planetary shocks depend on plasma beta, interplanetary magnetic field (IMF) spiral angle and Mach number, the amount of heating, acceleration efficiencies, etc. significantly change with heliocentric distance. In turn the waves seen at each planet propagate not in the same but different (physical) propagation modes. In this paper we compare the ULF wave observations at an outer and an inner planet. We use the results of the ratio, quantites easily derivable with sufficient accuracy at each planet. We use the full electromagnetic dispersion relation for comparison with theoretical predictions.

Classical Heat-Flux Measurements in Coronal Plasmas from Collective Thomson-Scattering Spectra

NASA Astrophysics Data System (ADS)

Henchen, R. J.; Hu, S. X.; Katz, J.; Froula, D. H.; Rozmus, W.

2016-10-01

Collective Thomson scattering was used to measure heat flux in coronal plasmas. The relative amplitude of the Thomson-scattered power into the up- and downshifted electron plasma wave features was used to determine the flux of electrons moving along the temperature gradient at three to four times the electron thermal velocity. Simultaneously, the ion-acoustic wave features were measured. Their relative amplitude was used to measure the flux of the return-current electrons. The frequencies of these ion-acoustic and electron plasma wave features provide local measurements of the electron temperature and density. These spectra were obtained at five locations along the temperature gradient in a laser-produced blowoff plasma. These measurements of plasma parameters are used to infer the Spitzer-Härm flux (qSH = - κ∇Te ) and are in good agreement with the values of the heat flux measured from the scattering-feature asymmetries. Additional experiments probed plasma waves perpendicular to the temperature gradient. The data show small effects resulting from heat flux compared to probing waves along the temperature gradient. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Coherent control of plasma dynamics

NASA Astrophysics Data System (ADS)

He, Zhaohan

2014-10-01

The concept of coherent control - precise measurement or determination of a process through control of the phase of an applied oscillating field - has been applied to numerous systems with great success. Here, we demonstrate the use of coherent control on plasma dynamics in a laser wakefield electron acceleration experiment. A tightly focused femtosecond laser pulse (10 mJ, 35 fs) was used to generate electron beams by plasma wakefield acceleration in the density down ramp. The technique is based on optimization of the electron beam using a deformable mirror adaptive optical system with an iterative evolutionary genetic algorithm. The image of the electrons on a scintillator screen was processed and used in a fitness function as direct feedback for the optimization algorithm. This coherent manipulation of the laser wavefront leads to orders of magnitude improvement to the electron beam properties such as the peak charge and beam divergence. The laser beam optimized to generate the best electron beam was not the one with the ``best'' focal spot. When a particular wavefront of laser light interacts with plasma, it can affect the plasma wave structures and trapping conditions of the electrons in a complex way. For example, Raman forward scattering, envelope self-modulation, relativistic self-focusing, and relativistic self-phase modulation and many other nonlinear interactions modify both the pulse envelope and phase as the pulse propagates, in a way that cannot be easily predicted and that subsequently dictates the formation of plasma waves. The optimal wavefront could be successfully determined via the heuristic search under laser-plasma conditions that were not known a priori. Control and shaping of the electron energy distribution was found to be less effective, but was still possible. Particle-in-cell simulations were performed to show that the mode structure of the laser beam can affect the plasma wave structure and trapping conditions of electrons, which subsequently produces electron beams with a different divergence. The proof-of-principle demonstration of coherent control for plasmas opens new possibilities for future laser-based accelerators and their applications. This study should also enable a significantly improved understanding of the complex dynamics of laser plasma interactions. This work was supported by DARPA under Contract No. N66001-11-1-4208, the NSF under Contract No. 0935197 and MCubed at the University of Michigan.

A Finite-Difference Time-Domain Model of Artificial Ionospheric Modification

NASA Astrophysics Data System (ADS)

Cannon, Patrick; Honary, Farideh; Borisov, Nikolay

Experiments in the artificial modification of the ionosphere via a radio frequency pump wave have observed a wide range of non-linear phenomena near the reflection height of an O-mode wave. These effects exhibit a strong aspect-angle dependence thought to be associated with the process by which, for a narrow range of off-vertical launch angles, the O-mode pump wave can propagate beyond the standard reflection height at X=1 as a Z-mode wave and excite additional plasma activity. A numerical model based on Finite-Difference Time-Domain method has been developed to simulate the interaction of the pump wave with an ionospheric plasma and investigate different non-linear processes involved in modification experiments. The effects on wave propagation due to plasma inhomogeneity and anisotropy are introduced through coupling of the Lorentz equation of motion for electrons and ions to Maxwell’s wave equations in the FDTD formulation, leading to a model that is capable of exciting a variety of plasma waves including Langmuir and upper-hybrid waves. Additionally, discretized equations describing the time-dependent evolution of the plasma fluid temperature and density are included in the FDTD update scheme. This model is used to calculate the aspect angle dependence and angular size of the radio window for which Z-mode excitation occurs, and the results compared favourably with both theoretical predictions and experimental observations. The simulation results are found to reproduce the angular dependence on electron density and temperature enhancement observed experimentally. The model is used to investigate the effect of different initial plasma density conditions on the evolution of non-linear effects, and demonstrates that the inclusion of features such as small field-aligned density perturbations can have a significant influence on wave propagation and the magnitude of temperature and density enhancements.

Arbitrary electron acoustic waves in degenerate dense plasmas

NASA Astrophysics Data System (ADS)

Rahman, Ata-ur; Mushtaq, A.; Qamar, A.; Neelam, S.

2017-05-01

A theoretical investigation is carried out of the nonlinear dynamics of electron-acoustic waves in a collisionless and unmagnetized plasma whose constituents are non-degenerate cold electrons, ultra-relativistic degenerate electrons, and stationary ions. A dispersion relation is derived for linear EAWs. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated in such a degenerate dense plasma. It is shown that only negative large amplitude EA solitary waves can exist in such a plasma system. The present analysis may be important to understand the collective interactions in degenerate dense plasmas, occurring in dense astrophysical environments as well as in laser-solid density plasma interaction experiments.

Ponderomotive Force and Lower Hybrid Turbulence Effects in Space Plasmas Subjected to Large-Amplitude Low-Frequency Waves

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Khazanov, George; Liemohn, M. W.; Stone, N. H.; Coffey, V. N.

1997-01-01

In the auroral region, simultaneous occurrences of upward-flowing ions and field-aligned electrons have been observed by the Viking satellite. The occurrence is strongly correlated with large amplitude low frequency fluctuations of the electric field. Large-amplitude shear Alfven waves have also been observed by sounding rockets in the auroral ionosphere. When such LF waves are propagating in a plasma, a ponderomotive force and other types of waves are produced which may lead to significant effects on the plasma. This force is directed toward decreasing density, providing the electromagnetic lift of the background plasma and an increase of collisionless plasma expansion. We find that even for modest wave strengths, the influence on the outflowing oxygen ions can be dramatic, increasing the high-altitude density by orders of magnitude. It is also demonstrated that large-amplitude low-frequency waves (LFW) may generate lower hybrid waves (LHW) in the auroral zone. The excitation of LHW by a LF wave may lead to the appearance of an additional channel of energy transfer from, for example, Alfven or fast magnetosonic waves, to particles. This process then influences the formation of the plasma distribution function at the expense of acceleration in the tail of the distribution during the collapse of the LHW. The ion energization due to the LHW can be comparable with that produced by the ponderomotive force of the LFW. It is shown that the LH turbulence leads to equalization of the ponderomotive acceleration of the different ion species. The mechanism of LHW excitation due to the oxygen ion relative drift in a plasma subjected to low-frequency waves is used for analysis of Viking satellite data for events in the cusp/cleft region. It is found that, in some cases, such a mechanism leads to LHW energy densities and ion distribution functions close to those observed.