UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

Guest
2024-11-22 2:35
 HOME     CONFERENCES     SEARCH            LOGIN     NEW USER     IMAGES   


Conference: Bucharest University Faculty of Physics 2003 Meeting


Section: Electricity and Biophysics


Title:
Chaotic behavior of linear motion in hexapolar rf traps.


Authors:
C. M. Niculae and P. Cristea,


Affiliation:
University of Bucharest, Electricity and Biophysics Dept.


E-mail


Keywords:


Abstract:
Linear motions in hexapolar radiofrequency (rf) trap obey the nonautonomous equation: s``=s^2*cos(t) (1). Using numerical integration, Fourier analysis and a special numeric method, the stability domains of this equation are studied and Poincare maps are derived. For large initial amplitude the particle motion obeying (1) are unbounded. Previous studies [1-4] of this motion proved the existence of bounded motion for small initial amplitudes. At intermediary initial amplitudes the character of bonded and unbounded motion appears alternately. The width of strands (on initial amplitude axis) defined in this way, for bounded motion, decreases as initial amplitude increases. Chaotic behavior of linear motion becomes obviously at the superior limit of the large strand containing the zero amplitude. Our study focused on this domain and on the intermediary domain above defined. The map of the Poincare section made up at constant rf field phase shows fine details of the chaotic character of this motion. To obtain details about the splitting of a large torus into small tori (appearing in the phase plane) the Fourier analysis was used. A special numeric method has been developed for fine Fourier analysis. This method, based on topological consideration, allowed an accurate counting of the tori number. Furthermore, the same method allowed identification of various satellites appearing in the frequency domain of the Fourier analysis. References 1. C. M. Niculae, "A simple method for studying motional stability in higher-order rf traps", Europhys. Lett., 43 (4), pp.398-403 (1998). 2. C. M. Niculae, "Linear trajectories in multipole rf traps", Rom. Rep. in Phys. 50 (7-8-9), pp.665-670 (1998). 3. C. M. Niculae and P. I. Cristea, "General Aspects of the Linear Motion in the Sextupole RF Trap", The Second Conference in Physics - Theodor Ionescu Centenary, Faculty of Physics, University of Bucharest, Bucharest-Magurele, 22 - 23 may 1999. 4. P. I. Cristea, C. M. Niculae, M. P. Dinca, "On the Motion Induced by the Unlinear Equation z``(*)=z^n*cos(t)", The Second Conference in Physics - Theodor Ionescu Centenary, Faculty of Physics, University of Bucharest, Bucharest-Magurele, 22 - 23 may 1999.