Studies of Parametric Decay Instabilities in Magneto Plasmas.
Abstract
A theory is developed for the parametric excitation of coupled waves in a uniform magneto plasma. Instead of using electrostatic approximation which is valid only for longitudinal waves, a general formulation of the parametric coupling equations is developed by using Hamiltonian approach. The plasma is pumped by a monochromatic electromagnetic wave with frequency which decays into two decay waves (e.g., a plasmon and a phonon). Either one of the plasma modes coupled with the pump wave (through the linearized Vlasov equation) to induce a polarization which may act as the source of another mode. A general procedure to calculate the induced polarizations is introduced by transforming the linearized Vlasov equation into the oscillating frame of reference, in which the equation can then be solved by the method of characteristics. The threshold power, initial growth rate and the frequency shift (due to finite initial growth rate) of the parametric instabilities can be obtained from the coupled mode equations and the results obtained can be applied to all the wavelength region. Several interesting cases are presented and compared favorably with experiments. The simultaneous excitation of second harmonic of electron-cyclotron and electrostatic ion-cyclotron oscillations by means of a monochromatic electromagnetic wave at frequency = 9.23 GHz has been observed experimentally.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1977
- Accession Number
- ADA049547
Entities
People
- Bernard R-s. Cheo
- Szu-ping Kuo