Delineating the magnetic field line escape pattern and stickiness in a poloidally diverted tokamak

We analyze a Hamiltonian model with five wire loops that delineates magnetic surfaces of tokamaks with poloidal divertor. Non-axisymmetric magnetic perturbations are added by external coils, similar to the correction coils that have been installed or designed in present tokamaks. To show the influence of magnetic perturbations on the field line escape, we integrate numerically the field line differential equations and obtain the footprints and deposition patterns on the divertor plate. Moreover, we show that the homoclinic tangle describes the deposition patterns in the divertor plate, agreeing with results observed in sophisticated simulation codes. Additionally, we show that while chaotic lines escape to the divertor plates, some of them are trapped, for many toroidal turns, in complex structures around magnetic islands, embedded in the chaotic region, giving rise to stickiness evidences characteristic of chaotic Hamiltonian systems. Finally, we introduce a random collisional term to the field line mapp...

[1]  I. Caldas,et al.  Onset of shearless magnetic surfaces in tokamaks , 2014 .

[2]  I. Caldas,et al.  Set of wires to simulate tokamaks with poloidal divertor , 2013, Journal of Plasma Physics.

[3]  J. D. Szezech,et al.  Effective transport barriers in nontwist systems. , 2012, Physical review. E, Statistical, nonlinear, and soft matter physics.

[4]  I. L. Caldas,et al.  Collisional effects in the tokamap , 2011 .

[5]  M A F Sanjuán,et al.  Fractal structures in nonlinear plasma physics , 2011, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[6]  M. Harsoula,et al.  Stickiness Effects in Conservative Systems , 2010, Int. J. Bifurc. Chaos.

[7]  Neil Mitchell,et al.  Overview of the ITER Correction Coils Design , 2010, IEEE Transactions on Applied Superconductivity.

[8]  J. D. Szezech,et al.  Transport properties in nontwist area-preserving maps. , 2009, Chaos.

[9]  T. Osborne,et al.  Overview of the results on divertor heat loads in RMP controlled H-mode plasmas on DIII-D , 2009 .

[10]  A. Boozer,et al.  Stochastic layer scaling in the two-wire model for divertor tokamaks , 2009, Journal of Plasma Physics.

[11]  K. Spatschek,et al.  High resolution numerical studies of separatrix splitting due to non-axisymmetric perturbation in DIII-D , 2009 .

[12]  K. Spatschek,et al.  Footprint structures due to resonant magnetic perturbations in DIII-D , 2009 .

[13]  K. Spatschek,et al.  Aspects of three dimensional transport for ELM control experiments in ITER-similar shape plasmas at low collisionality in DIII-D , 2008 .

[14]  J. Contributors,et al.  Accuracy of EFIT equilibrium reconstruction with internal diagnostic information at JET. , 2008, The Review of scientific instruments.

[15]  R. Viana,et al.  Escape patterns of chaotic magnetic field lines in a tokamak with reversed magnetic shear and an ergodic limiter , 2008 .

[16]  Alfredo Portone,et al.  ITER shape controller and transport simulations , 2007 .

[17]  S. Abdullaev,et al.  Mappings of stochastic field lines in poloidal divertor tokamaks , 2006 .

[18]  S. Abdullaev,et al.  Heat deposition patterns on the target plates of the dynamic ergodic divertor , 2005 .

[19]  T. Evans,et al.  The low MN map for single-null divertor tokamaks , 2004 .

[20]  T. Evans,et al.  Explicit calculations of homoclinic tangles in tokamaks , 2003 .

[21]  Miguel A. F. Sanjuán,et al.  Escape patterns, magnetic footprints, and homoclinic tangles due to ergodic magnetic limiters , 2002 .

[22]  T. Evans,et al.  Modeling of stochastic magnetic flux loss from the edge of a poloidally diverted tokamak , 2002 .

[23]  D. W. Faulconer,et al.  Plasma rotation induced by the Dynamic Ergodic Divertor , 2001 .

[24]  M. Tokar.  On transport, in particular of impurities, in a stochastic magnetic field , 1999 .

[25]  U. Daybelge,et al.  Pattern of ion bombardment on the poloidal divertor plates , 1999 .

[26]  P. Ghendrih,et al.  REVIEW ARTICLE: Theoretical and experimental investigations of stochastic boundaries in tokamaks , 1996 .

[27]  G. Janeschitz,et al.  Status of ITER , 1995 .

[28]  A. Reiman.  Singular surfaces in the open field line region of a diverted tokamak , 1995 .

[29]  A. Reiman,et al.  Effect of nonaxisymmetric perturbations on the structure of a tokamak poloidal divertor , 1992 .

[30]  M. Benkadda,et al.  Diffusion in the noisy Chirikov-Taylor mapping , 1990 .

[31]  F. Wagner,et al.  Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak , 1982 .

[32]  W. Stacey.  Fusion Plasma Analysis , 1981 .

[33]  A. Boozer,et al.  Effect of magnetic perturbations on divertor scrape-off width , 1978 .