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Your search keyword '"Allen, J. E."' showing total 810 results
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810 results on '"Allen, J. E."'

1. Propagation of periodic wave trains along the magnetic field in a collision-free plasma

Author

Abbas, G., Kevrekidis, P. G., Allen, J. E., Koukouloyannis, V., Frantzeskakis, D. J., and Karachalios, N.

Subjects
Nonlinear Sciences - Pattern Formation and Solitons
Abstract

In this work, a systematic study, examining the propagation of periodic and solitary wave along the magnetic field in a cold collision-free plasma, is presented. Employing the quasi-neutral approximation and the conservation of momentum flux and energy flux in the frame co-traveling with the wave, the exact analytical solution of the stationary solitary pulse is found analytically in terms of particle densities, parallel and transverse velocities, as well as transverse magnetic fields. Subsequently, this solution is generalized in the form of periodic waveforms represented by cnoidal-type waves. These considerations are fully analytical in the case where the total angular momentum flux $L$, due to the ion and electron motion together with the contribution due to the Maxwell stresses, vanishes. A graphical representation of all associated fields is also provided.

Published
2020
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2. Nonlinear solitary wave parallel propagation and particle dynamics in a cold, collision-free, magnetized plasma in the presence of dust.

Author

Causa, F., Allen, J. E., and Iqbal, Z.

Abstract

Dust plays a key role in solitary wave propagation in a plasma, giving rise to slow waves and a variety of interesting features dependent on dust mass and charge. To simplify the analysis, based on the Adlam–Allen method, two cases are studied here, those of heavy dust and ion–dust coupling, retaining the dynamics of both. The main result is that resonant conditions corresponding to well-localized circularly polarized solutions exist for any value of the relative dust density, in both cases. Scaled resonance conditions were derived in both cases, for varying dust mass and charge, as functions of the relative density. Characteristic fields, particle density, and particle velocity calculated at resonance were presented in both regimes of interest, for the representative case of a hydrogen plasma. Further solutions are obtained corresponding to unconventional particle oscillations, presenting equally unconventional electric field profiles or magnetic field polarization, to be studied and pursued in greater detail in dedicated work. [ABSTRACT FROM AUTHOR]

Published
2025
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4. Cylindrical plasmas generated by an annular beam of ultraviolet light

Author

Thomas, D. M. and Allen, J. E.

Subjects
Physics - Plasma Physics
Abstract

We investigate a cylindrical plasma system with ionization, by an annular beam of ultraviolet light, taking place only in the cylinder's outer region. In the steady state, both the outer and inner regions contain a plasma, with that in the inner region being uniform and field-free. At the interface between the two regions, there is an infinitesimal jump in ion density, the magnitude approaching zero in the quasi-neutral $(\lambda_D \rightarrow 0)$ limit. The system offers the possibility of producing a uniform stationary plasma in the laboratory, hitherto obtained only with thermally produced alkali plasmas., Comment: 5 figures

Published
2015
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5. The effect of dust on the propagation of a hydromagnetic solitary wave along the magnetic field in a cold collision-free plasma.

Author

Iqbal, Z., Allen, J. E., Causa, F., Abbas, G., Ridgway, Wesley J. M., and Koukouloyannis, V.

Subjects
*MAGNETOHYDRODYNAMIC waves, *NONLINEAR differential equations, *MACH number, *NONLINEAR equations, *MAGNETIC fields
Abstract

The effect of dust is studied on the parallel propagation of a solitary hydromagnetic wave in a magnetized, cold, collision-free plasma. The fully nonlinear analysis is based on the Adlam–Allen method. The system of nonlinear differential equations was derived using the assumption of massive dust, namely, that the dust velocity is constant and parallel to the background magnetic field. Self-consistent solutions obtained from the model for the lighter particles dynamics and for the resulting electric and magnetic fields are presented, together with the validity range of Mach numbers as a function of dust parameters. In particular, supersonic solutions are possible in scenarios tending to two-component plasmas (positively charged ions and negatively charged dust). The stationary solitary pulse in terms of particle densities, magnitude of transverse magnetic field, transverse electron–ion velocities, and bipolar electric field is presented. The magnitude of these amplitudes is maximum at the center of wave and minimum at the boundary. Furthermore, it is shown that all the solitary wave amplitudes are decreases with dust parameter. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Plasmas generated by ultra-violet light rather than electron impact

Author

Franklin, R. N., Allen, J. E., Thomas, D. M., and Benilov, M. S.

Subjects
Physics - Plasma Physics
Abstract

We analyze, in both plane and cylindrical geometries, a collisionless plasma consisting of an inner region where generation occurs by UV illumination, and an un-illuminated outer region with no generation. Ions generated in the inner region flow outwards through the outer region and into a wall. We solve for this system's steady state, first in the quasi-neutral regime (where the Debye length ${\lambda}_D$ vanishes and analytic solutions exist) and then in the general case, which we solve numerically. In the general case a double layer forms where the illuminated and un-illuminated regions meet, and an approximately quasi-neutral plasma connects the double layer to the wall sheath; in plane geometry the ions coast through the quasi-neutral section at slightly more than the Bohm speed $c_s$. The system, although simple, therefore has two novel features: a double layer that does not require counter-streaming ions and electrons, and a quasi-neutral plasma where ions travel in straight lines with at least the Bohm speed. We close with a pr\'{e}cis of our asymptotic solutions of this system, and suggest how our theoretical conclusions might be extended and tested in the laboratory., Comment: 10 pages, 3 figures, accepted by Physics of Plasmas

Published
2013
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7. Acceleration of dust particles by vortex ring

Author

Ehsan, Zahida, Tsintsadze, N. L., Vranjes, J., Coppins, M., Khan, R., Poedts, S., and Allen, J. E.

Subjects
Physics - Plasma Physics
Abstract

It is shown that nonlinear interaction between large amplitude circularly polarized EM wave and dusty plasma leads to a nonstationary ponderomotive force which in turn produces a vortex ring, and magnetic field. Then the ensuing vortex ring in the direction of propagation of the pump wave can accelerate the micron-size dust particles which are initially at rest and eventually form a non relativistic dust jet. This effect is purely nonstationary and unlike linear vortices, dust particles do not rotate here. Specifically, it is pointed out that the vortex ring or closed filament can become potential candidate for the acceleration of dust in tokamak plasmas.

Published
2009

8. The Transcriptional Landscape of the Mammalian Genome

Author

Carninci, P., Kasukawa, T., Katayama, S., Gough, J., Frith, M. C., Maeda, N., Oyama, R., Ravasi, T., Lenhard, B., Wells, C., Kodzius, R., Shimokawa, K., Bajic, V. B., Brenner, S. E., Batalov, S., Forrest, A. R. R., Zavolan, M., Davis, M. J., Wilming, L. G., Aidinis, V., Allen, J. E., Ambesi-Impiombato, A., Apweiler, R., Aturaliya, R. N., Bailey, T. L., Bansal, M., Baxter, L., Beisel, K. W., Bersano, T., Bono, H., Chalk, A. M., Chiu, K. P., Choudhary, V., Christoffels, A., Clutterbuck, D. R., Crowe, M. L., Dalla, E., Dalrymple, B. P., de Bono, B., Della Gatta, G., di Bernardo, D., Down, T., Engstrom, P., Fagiolini, M., Faulkner, G., Fletcher, C. F., Fukushima, T., Furuno, M., Futaki, S., Gariboldi, M., Georgii-Hemming, P., Gingeras, T. R., Gojobori, T., Green, R. E., Gustincich, S., Harbers, M., Hayashi, Y., Hensch, T. K., Hirokawa, N., Hill, D., Huminiecki, L., Iacono, M., Ikeo, K., Iwama, A., Ishikawa, T., Jakt, M., Kanapin, A., Katoh, M., Kawasawa, Y., Kelso, J., Kitamura, H., Kitano, H., Kollias, G., Krishnan, S. P. T., Kruger, A., Kummerfeld, S. K., Kurochkin, I. V., Lareau, L. F., Lazarevic, D., Lipovich, L., Liu, J., Liuni, S., McWilliam, S., Babu, M. Madan, Madera, M., Marchionni, L., Matsuda, H., Matsuzawa, S., Miki, H., Mignone, F., Miyake, S., Morris, K., Mottagui-Tabar, S., Mulder, N., Nakano, N., Nakauchi, H., Ng, P., Nilsson, R., Nishiguchi, S., Nishikawa, S., Nori, F., Ohara, O., Okazaki, Y., Orlando, V., Pang, K. C., Pavan, W. J., Pavesi, G., Pesole, G., Petrovsky, N., Piazza, S., Reed, J., Reid, J. F., Ring, B. Z., Ringwald, M., Rost, B., Ruan, Y., Salzberg, S. L., Sandelin, A., Schneider, C., Schöbach, C., Sekiguchi, K., Semple, C. A. M., Seno, S., Sessa, L., Sheng, Y., Shibata, Y., Shimada, H., Shimada, K., Silva, D., Sinclair, B., Sperling, S., Stupka, E., Sugiura, K., Sultana, R., Takenaka, Y., Taki, K., Tammoja, K., Tan, S. L., Tang, S., Taylor, M. S., Tegner, J., Teichmann, S. A., Ueda, H. R., van Nimwegen, E., Verardo, R., Wei, C. L., Yagi, K., Yamanishi, H., Zabarovsky, E., Zhu, S., Zimmer, A., Hide, W., Bult, C., Grimmond, S. M., Teasdale, R. D., Liu, E. T., Brusic, V., Quackenbush, J., Wahlestedt, C., Mattick, J. S., Hume, D. A., Kai, C., Sasaki, D., Tomaru, Y., Fukuda, S., Kanamori-Katayama, M., Suzuki, M., Aoki, J., Arakawa, T., Iida, J., Imamura, K., Itoh, M., Kato, T., Kawaji, H., Kawagashira, N., Kawashima, T., Kojima, M., Kondo, S., Konno, H., Nakano, K., Ninomiya, N., Nishio, T., Okada, M., Plessy, C., Shibata, K., Shiraki, T., Suzuki, S., Tagami, M., Waki, K., Watahiki, A., Okamura-Oho, Y., Suzuki, H., and Kawai, J.

Published
2005

45. Epigenetic control of Th2 induction by dendritic cells: W30.006

Author

Cook, P. C., Deaton, A., Owen, H., Thomas, G., Jones, L. H., Phythian-Adams, A. T., Lundie, R. J., Webb, L. M., Marley, A. K., Borger, J. G., Sutherland, T. E., Allen, J. E., Grainger, J. R., Maizels, R. M., Ivens, A., Bird, A., and MacDonald, A. S.

Published
2012

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