Experimental observation of Alfven wave cones
- Department of Physics, University of California at Los Angeles, Los Angeles, California 90024-1696 (United States)
The spatial evolution of the radial profile of the magnetic field of a shear Alfven wave launched by a disk exciter with radius on the order of the electron skin depth has been measured. The waves are launched using wire mesh disk exciters of 4 mm and 8 mm radius into a helium plasma of density about 1.0[times]10[sup 12] cm[sup [minus]3] and magnetic field 1.1 kG. The electron skin depth [delta]=[ital c]/[omega][sub [ital pe]] is about 5 mm. The current channel associated with the shear Alfven wave is observed to spread with distance away from the exciter. The spreading follows a cone-like pattern whose angle is given by tan [theta]=[ital k][sub A][delta], where [ital k][sub A] is the Alfven wave number. The dependence of the magnetic profiles on wave frequency and disk size are presented. The effects of dissipation by electron--neutral collisions and Landau damping are observed. The observations are in excellent agreement with theoretical predictions [Morales [ital et] [ital al]., Phys. Plasmas [bold 1], 3765 (1994)].
- OSTI ID:
- 6635304
- Journal Information:
- Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:12; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
700370 -- Plasma Fluid & MHD Properties-- (1992-)
ALFVEN WAVES
ATOM COLLISIONS
COLLISIONS
DAMPING
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
FLUID MECHANICS
FLUIDS
GASES
HELIUM
HYDRODYNAMICS
HYDROMAGNETIC WAVES
LANDAU DAMPING
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
NONMETALS
RARE GASES
SKIN EFFECT