TITLE

Nonlinear electron magnetohydrodynamic physics. VII. Magnetic loop antenna in a field-free plasma

AUTHOR(S)
Stenzel, R. L.; Urrutia, J. M.; Strohmaier, K. D.
PUB. DATE
February 2009
SOURCE
Physics of Plasmas;Feb2009, Vol. 16 Issue 2, pN.PAG
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Nonlinear whistler phenomena near a magnetic loop antenna in a field-free plasma have been investigated experimentally. The loop field oscillates at a frequency far below the electron plasma frequency, hence all linear electromagnetic modes are cut off. However, the peak antenna field is so large that the electrons become magnetized allowing whistler modes to exist in the near zone of the antenna. The shielding magnetic field propagates at a speed which increases with magnetic field strength and decays slower than the rf period, resulting in a remnant field when the antenna field vanishes. A field-reversed configuration (FRC) is produced when the antenna field reverses direction. The FRC expands into the magnetized plasma and produces self-consistent magnetic helicity consistent with that of whistler modes. Thus, the new field penetrates in the whistler mode in a background field left over from the previous half-cycle. The electrons become unmagnetized at large distances, and the field convection goes over into field diffusion. Observations of light emission indicate electron energization. Current-driven instabilities produce magnetic oscillations with frequencies much higher than the applied one. Small amplitude, high-frequency whistlers propagate in the large amplitude fields of the low-frequency whistler, but become absorbed at larger distances where the cyclotron frequency decreases below the wave frequency. The nonlinear phenomena observed may be relevant to inductively coupled plasma sources, laser-plasma interactions, plasma opening switches, and active experiments in space.
ACCESSION #
36810481

 

Related Articles

  • Dynamics of nonlinearly coupled magnetic-field-aligned electromagnetic electron-cyclotron waves near the zero-group-dispersion point in magnetized plasmas. Kourakis, I.; Shukla, P. K.; Morfill, G. E. // Physics of Plasmas;Aug2005, Vol. 12 Issue 8, p082303 

    The nonlinear coupling between two magnetic-field-aligned electromagnetic electron-cyclotron (EMEC) waves in plasmas is considered. Evaluating the ponderomotive coupling between the EMEC waves and quasistationary plasma density perturbations, a pair of coupled nonlinear Schrödinger equations...

  • Alfvén-wave heating of a high-beta plasma column. Cekic, M.; Nelson, B. A.; Ribe, F. L. // Physics of Fluids B: Plasma Physics;Feb92, Vol. 4 Issue 2, p392 

    Alfvén-wave heating experiments are performed on the High Beta Q Machine (HBQM) [Phys. Fluids 25, 262 (1982)] straight plasma column. An investigation is made of Alfvén-wave energy absorption by the Alfvén-resonant layer at which the local shear Alfvén velocity is equal to the phase...

  • Stability of pure electron plasmas on magnetic surfaces. Boozer, Allen H. // Physics of Plasmas;Oct2004, Vol. 11 Issue 10, p4709 

    The electrostatic analog of magnetohydrodynamic stability for a pure electron plasma on magnetic surfaces is examined. Perturbations that conserve the number of particles and the entropy of the plasma as well as maintain force balance and a temperature that is a spatial constant along the...

  • Experimental evidence of fast reconnection via trapped electron motion. Egedal, J.; Fox, W.; Porkolab, M.; Fasoli, A. // Physics of Plasmas;May2004, Vol. 11 Issue 5, p2844 

    Magnetic reconnection in collisionless magnetohydrodynamic plasmas is studied under controlled conditions in toroidal X-line configurations formed in the center of the Versatile Toroidal Facility [J. Egedal et al., Rev. Sci. Instrum. 71, 3351 (2000)]. Profiles of key parameters are measured...

  • Nonlinear electron magnetohydrodynamics physics. V. Triggered whistler emissions. Stenzel, R. L.; Strohmaier, K. D.; Urrutia, J. M. // Physics of Plasmas;Jun2008, Vol. 15 Issue 6, p062110 

    Laboratory experiments on whistler instabilities in the presence of small trigger waves have been performed. The instabilities arise from energizing electrons in magnetic null lines with time-varying magnetic fields. Such fields are created with loop antennas carrying large oscillating currents...

  • Nonlinear electron magnetohydrodynamic physics. VI. Magnetic loop antenna across the ambient field. Urrutia, J. M.; Stenzel, R. L.; Strohmaier, K. D. // Physics of Plasmas;Feb2009, Vol. 16 Issue 2, pN.PAG 

    Laboratory experiments on nonlinear whistler phenomena near a magnetic loop antenna with axis across the magnetic field are presented. The field topologies, radiation efficiency, electron energization and instabilities in the low-frequency whistler regime have been investigated. The...

  • New low-frequency electromagnetic modes associated with neutral dynamics in partially ionised plasma. Shaikh, A. A.; Das, A. C. // Annales Geophysicae (09927689);2013, Vol. 31 Issue 5, p983 

    We have investigated the low frequency electromagnetic (EM) modes in inhomogeneous, magnetised partially ionised plasma by incorporating neutral dynamics. We have derived a general EM dispersion relation by using a two-fluids magnetohydrodynamics (MHD) model. Our analysis shows that the neutral...

  • Some results of measuring the characteristics of electromagnetic and plasma disturbances stimulated in the outer ionosphere by high-power high-frequency radio emission from the �Sura� facility. Rapoport, V. O.; Frolov, V. L.; Komrakov, G. P.; Markov, G. A.; Belov, A. S.; Parrot, M.; Rauch, J. L. // Radiophysics & Quantum Electronics;Aug2007, Vol. 50 Issue 8, p645 

    We present the results of measuring the characteristics of electromagnetic and plasma disturbances at altitudes of about 700 km, obtained by using the onboard equipment of the French microsatellite DEMETER during its passage through the magnetic tube resting upon the region of intense generation...

  • Low-Power Inductive RF Plasma Sources for Technological Applications. Vavilin, K. V.; Rukhadze, A. A.; Ri, M. Kh.; Plaksin, V. Yu. // Plasma Physics Reports;Aug2004, Vol. 30 Issue 8, p687 

    The objective of the present paper is to develop an analytic theory of cylindrical low-power RF plasma sources operating at an industrial frequency (f = 13.56 MHz, ? = 8.52 � 107s�1). Inductive surface exciters of electromagnetic fields (exciting antennas) are considered that are...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics