Ergodic Magnetic Limiter with Barrier
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A barrier is produced to radial diffusion of chaotic field lines and consequently increasing the particles confinement time. The chaotic layer near the plasma edge is created by perturbed Hamiltonian (of order ε) of an ergodic magnetic limiter (EML). Adding a control term of order ε 2 to this perturbed Hamiltonian revives invariant tori acting as barriers against plasma particles diffusion. The location of the barrier could be chosen in the chaotic zone of EML at a given place near the edge of plasma column. The chaotic behavior of the magnetic field lines around the barrier is studied by utilizing the maximal Lyapunov exponent, average square displacement (diffusion) and invariant manifolds. The effect of changing the number of EML rings on the barrier is investigated. A barrier is also generated by considering special modes in the Fourier expansion of the perturbed Hamiltonian.
KeywordsHamiltonian chaos Transport barrier Ergodic magnetic limiter Symplectic maps Tokamak
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