Competition of Self-Organized Rotating Spiral Autowaves in a Nonequilibrium Dissipative System of Three-Level Phaser

We present results of cellular automata based investigations of rotating spiral autowaves in a nonequilibrium excitable medium which models three-level paramagnetic microwave phonon laser (phaser). The computational model is described in arXiv:cond-mat/0410460v2 and arXiv:cond-mat/0602345v1 . We have observed several new scenarios of self-organization, competition and dynamical stabilization of rotating spiral autowaves under conditions of cross-relaxation between three-level active centers. In particular, phenomena of inversion of topological charge, as well as processes of regeneration and replication of rotating spiral autowaves in various excitable media were revealed and visualized for mesoscopic-scale areas of phaser-type active systems, which model real phaser devices.

Emergence, Competition and Dynamical Stabilization of Dissipative Rotating Spiral Waves in an Excitable Medium: A Computational Model Based on Cellular Automata

We report some qualitatively new features of emergence, competition and dynamical stabilization of dissipative rotating spiral waves (RSWs) in the cellular-automaton model of laser-like excitable media proposed in arXiv:cond-mat/0410460v2 ; arXiv:cond-mat/0602345 . Part of the observed features are caused by unusual mechanism of excitation vorticity when the RSW's core get into the surface layer of an active medium. Instead of the well known scenario of RSW collapse, which takes place after collision of RSW's core with absorbing boundary, we observed complicated transformations of the core leading to regeneration (nonlinear "reflection" from the boundary) of the RSW or even to birth of several new RSWs in the surface layer. Computer experiments on bottlenecked evolution of such the RSW-ensembles (vortex matter) are reported and a possible explanation of real experiments on spin-lattice relaxation in dilute paramagnets is proposed on the basis of an analysis of the RSWs dynamics. Chimera states in RSW-ensembles are revealed and compared with analogous states in ensembles of nonlocally coupled oscillators. Generally, our computer experiments have shown that vortex matter states in laser-like excitable media have some important features of aggregate states of the usual matter.

A Computational Study of Rotating Spiral Waves and Spatio-Temporal Transient Chaos in a Deterministic Three-Level Active System

Spatio-temporal dynamics of a deterministic three-level cellular automaton (TLCA) of Zykov-Mikhailov type (Sov. Phys. - Dokl., 1986, Vol.31, No.1, P.51) is studied numerically. Evolution of spatial structures is investigated both for the original Zykov-Mikhailov model (which is applicable to, for example, Belousov-Zhabotinskii chemical reactions) and for proposed by us TLCA, which is a generalization of Zykov-Mikhailov model for the case of two-channel diffusion. Such the TLCA is a minimal model for an excitable medium of microwave phonon laser, called phaser (D. N. Makovetskii, Tech. Phys., 2004, Vol.49, No.2, P.224; cond-mat/0402640). The most interesting observed forms of TLCA dynamics are as follows: (a) spatio-temporal transient chaos in form of highly bottlenecked collective evolution of excitations by rotating spiral waves (RSW) with variable topological charges; (b) competition of left-handed and right-handed RSW with unexpected features, including self-induced alteration of integral effective topological charge; (c) transient chimera states, i.e. coexistence of regular and chaotic domains in TLCA patterns; (d) branching of TLCA states with different symmetry which may lead to full restoring of symmetry of imperfect starting pattern. Phenomena (a) and (c) are directly related to phaser dynamics features observed earlier in real experiments at liquid helium temperatures on corundum crystals doped by iron-group ions. ACM: F.1.1, I.6, J.2; PACS:05.65.+b, 07.05.Tp, 82.20.Wt