Nonlinear physics of the ionosphere and LOIS/LOFAR

The ionosphere is the only large-scale plasma laboratory without walls that we have direct access to. From results obtained in systematic, repeatable experiments in this natural laboratory, where we can vary the stimulus and observe its response in a controlled, repeatable manner, we can draw conclusions on similar physical processes occurring naturally in the Earth's plasma environment as well as in parts of the plasma universe that are not easily accessible to direct probing. Of particular interest is electromagnetic turbulence excited in the ionosphere by beams of particles (photons, electrons) and its manifestation in terms of secondary radiation (electrostatic and electromagnetic waves), structure formation (solitons, cavitons, alfveons, striations), and the associated exchange of energy, linear momentum, and angular momentum. We present a new diagnostic technique, based on vector radio allowing the utilization of EM angular momentum (vorticity), to study plasma turbulence remotely.Comment: Six pages, two figures. To appear in Plasma Physics and Controlled Fusio

Utilization of photon orbital angular momentum in the low-frequency radio domain

We show numerically that vector antenna arrays can generate radio beams which exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (< 1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This opens up for new types of experiments that go beyond those currently possible to perform in optics, for information-rich radio physics applications such as radio astronomy, and for novel wireless communication concepts.Comment: 4 pages, 5 figures. Changed title, identical to the paper published in PR

O možnosti vsesplošnega nastopa mezofaze

Examples of real and model fluids, and circumstantial experimental evidence are presented in support of two hypotheses: A) the P, q, T surface of any real fluid exhibits at least two critical points, one of them possibly in the subcooled or solid state region; B) any substance may also exhibit an anisotropic phase of an intermediate order between the liquid and solid phases.Primeri modelne in realnih tekočin, ter posredni eksperimetalni dokazi so navedeni v podporo dveh hipotez : A) P, q, T ploskev vsake realne tekočine ima vsaj dve kritični točki, eno od njih morebiti v območju podhlajene tekočine ali trdne snovi; B) vsaka snov more imeti tuđi anizotropno fazo vmesne urejenosti med trdno in tekočo fazo