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Radiation of ion acoustic waves from a solid spherical probe in a warm isotropic plasma
Author(s) -
Malingre M.
Publication year - 1984
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs019i001p00400
Subject(s) - atomic physics , plasma , ion , debye length , physics , radius , amplitude , plasma parameters , electron , excitation , excited state , plasma oscillation , isotropy , ion acoustic wave , optics , quantum mechanics , computer security , computer science
The behavior of a solid spherical probe immersed in a warm isotropic collisionless plasma, biased to plasma potential, and excited from an alternating current source, is investigated for frequencies below the ion plasma frequency. A hydrodynamic description of the plasma is used, together with absorptive boundary conditions for the electrons and ions at the probe surface. Expressions are derived for the alternating potential in the plasma, as a function of frequency, of radial distance, of probe radius, and of the plasma parameters. Much of this potential is due to ion acoustic waves, the amplitude of which depends strongly on the ratio R p of the probe radius to the Debye length. As soon as R p exceeds the ratio ƒ/ƒ pe of the excitation frequency to the electron plasma frequency, the amplitude is reduced much below its value for R p = 0 corresponding to a point source. It is shown in particular that under some conditions, for values of R p over a certain limited range, this reduction is independent of R p . The smaller the ratio of the excitation frequency to the ion plasma frequency, the larger is this range.