摘要:

AbstractAn investigation is made of resonant excitation of helicon waves at the difference frequency of two microwave beams propagating in a magneto‐active solid state plasma viz. n‐InSb. The two beams propagating obliquely with the magnetostatic field interact in the semiconductor to give rise to a nonlinear ponderomotive force at the difference frequency which resonantly excites helicon waves if the dispersion relation corresponding to helicon waves is satisfied. The results show that microwave beams of power densities 1 MW cm−2can excite helicon waves of power density 0.98 kW cm−2when ωc/ω = 25. The power carried by helicon waves depends on the direction of propagation of the pumps relative to magnetostatic field. For the parameters under consideration the power gets optimised at an angle θ = 63.4°. Helicon waves are not excited if the pumps propagate parallel or perpendicular to the magnetic field. The increase in magnetic field increases the power density of the excited h

ISSN:0370-1972    

DOI:10.1002/pssb.2221330149

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractIt is shown that in a medium representing an example of “Koch's tree”‐type fractional structure the diffusion process is described by a generalized transfer equation in partial derivations. Such a structure can serve as a model of a porous medium where the diffusion process takes place. The geometry of an inhomogeneous medium can serve as the dicisive factor in the explanation of the “universal response” phenomenon. A range of frequencies is found where such “superslow” diffusion process ca

ISSN:0370-1972    

DOI:10.1002/pssb.2221330150

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0370-1972    

DOI:10.1002/pssb.2221330151

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0370-1972    

DOI:10.1002/pssb.2221330101

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY