Beat excitation of whistlers in the presence of field aligned irregularities in the ionosphere
- Department of Education, Lucknow University, Lucknow, UP (India)
In equatorial ionospheric plasma, embedded with a density ripple, a low frequency whistler can be resonantly excited by the nonlinear mixing of two high frequency radio waves launched from the ground at an oblique angle. A suitable configuration is where the earth magnetic field is along z (horizontal), ripple wave number q-vector parallel y (horizontal), and high frequency wave numbers are k-vector{sub 1}=k{sub 1} cos {theta}z+k{sub 1} sin {theta}(cos {phi}x+sin {phi}y), k-vector{sub 2}=-k{sub 2} cos {theta}z+k{sub 2} sin {theta}(cos {phi}x-sin {phi}y). Phase matching conditions are satisfied for large {theta} and small {phi}. The radio waves exert a ponderomotive force on electrons at the beat frequency imparting them an oscillatory velocity with a component perpendicular to the magnetic field. This velocity, in conjunction with the density ripple, produces a current that drives the whistler. The Ohmic nonlinearity is found to be relatively weaker in comparison to ponderomotive nonlinearity at higher heights. However in the E-region, this nonlinearity reinforces with the ponderomotive nonlinearity and can improve the whistler power generation.
- OSTI ID:
- 21120264
- Journal Information:
- Physics of Plasmas, Vol. 15, Issue 4; Other Information: DOI: 10.1063/1.2907357; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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