Hans H. Kuehl

Research Summary

Professor Kuehl's recent research thrust is the study of localized nonlinear pulses in plasmas and in optical fibers. Two important aspects of this research are the determination of the properties of laser-pulse solitary waves in a plasma, and of ion-acoustic solitary waves in a beam-plasma system. Solitary waves are important because they often have the unusual property that they travel for long distances without changing shape in a lossless, uniform environment. Solitons, which are solitary waves that retain their shape after colliding with each other, have an important technological impact in the area of fiber optic communication, where light pulses in the form of solitons are used for broadband information transmission. Solitons are also found in plasmas, fluids, crystal lattices, and nonlinear transmission lines.

The most recent research program is an analytical and numerical study of the characteristics of solitons and solitary waves in various plasma environments as well as the effect of small perturbations in the equations governing solitons. A major reason for studying perturbations on solitons and solitary waves is that in many physical systems in which the perturbation is controllable, it may be possible to adjust it in order to produce certain desired modifications of the soliton, such as reshaping, amplification, compression, or reflection. An important purpose of this research is the exploration of how the perturbation can be tailored to achieve specific soliton properties in nonlinear systems. The study of small perturbations on solitons is important because, although the effect is small, the accumulated modification of the soliton may be large when the perturbation acts over a long time period.

Professor Kuehl's major past research contributions include the formulation and development of the basic theory governing the interaction of antennas and plasmas. He was one of the first theoreticians to predict and describe in detail the phenomenon of plasma resonance cones, which produce significant enhancement of the electromagnetic fields of an antenna in a magnetized plasma. The resonance cone phenomenon plays an important role in the measurement of electron density and temperature in ionospheric and magnetospheric plasmas, and in the energy transfer of lower hybrid waves that are used for the heating of plasmas in fusion reactors.