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Interaction of two charges in a uniform magnetic field : II. spatial problem
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Pinheiro, D. and MacKay, R. S. (Robert Sinclair). (2008) Interaction of two charges in a uniform magnetic field : II. spatial problem. Journal of Nonlinear Science, Vol.18 (No.6). pp. 615666. ISSN 09388974
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Official URL: http://dx.doi.org/10.1007/s0033200890221
Abstract
The interaction of two charges moving in R3 in a magnetic field B can be formulated as a Hamiltonian system with six degrees of freedom. Assuming that the magnetic field is uniform and the interaction potential has rotation symmetry, we reduce this system to one with three degrees of freedom. For special values of the conserved quantities, choices of parameters or restriction to the coplanar case, we obtain systems with two degrees of freedom. Specialising to the case of Coulomb interaction, these reductions enable us to obtain many qualitative features of the dynamics. For charges of the same sign, the gyrohelices either "bounceback", "passthrough", or exceptionally converge to coplanar solutions. For charges of opposite signs, we decompose the state space into "free" and "trapped" parts with transitions only when the particles are coplanar. A scattering map is defined for those trajectories that come from and go to infinite separation along the field direction. It determines the asymptotic parallel velocities, guiding centre field lines, magnetic moments and gyrophases for large positive time from those for large negative time. In regimes where gyrophase averaging is appropriate, the scattering map has a simple form, conserving the magnetic moments and parallel kinetic energies (in a frame moving along the field with the centre of mass) and rotating or translating the guiding centre field lines. When the gyrofrequencies are in loworder resonance, however, gyrophase averaging is not justified and transfer of perpendicular kinetic energy is shown to occur. In the extreme case of equal gyrofrequencies, an additional integral helps us to analyse further and prove that there is typically also transfer between perpendicular and parallel kinetic energy.
Item Type:  Journal Article  

Subjects:  Q Science > QA Mathematics Q Science > QC Physics 

Divisions:  Faculty of Science > Mathematics  
Library of Congress Subject Headings (LCSH):  Hamiltonian systems, Euclidean algorithm, Reconstruction (Graph theory), Magnetic fields  
Journal or Publication Title:  Journal of Nonlinear Science  
Publisher:  Springer  
ISSN:  09388974  
Official Date:  December 2008  
Dates: 


Volume:  Vol.18  
Number:  No.6  
Number of Pages:  52  
Page Range:  pp. 615666  
Identifier:  10.1007/s0033200890221  
Status:  Peer Reviewed  
Publication Status:  Published  
Access rights to Published version:  Restricted or Subscription Access  
Funder:  Fundação para a Ciência e a Tecnologia (FCT), Universidade do Porto. Centro de Matematica  
Grant number:  SFRH/BD/9239/2002 (FCT), SFRH/BPD/27151/2006 (FCT)  
References:  Abraham, R., Marsden, J.: Foundations of Mechanics, 2nd edn. Benjamin/Cummings, Reading (1978) 

URI:  http://wrap.warwick.ac.uk/id/eprint/28908 
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