Tham khảo tài liệu 'nonlinear dynamics part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 68 Nonlinear Dynamics tangle intersects the horizontal divertor target plate at R m z m while another lobe intersects the vertical wall located at R m. The intersection of these homoclinic lobes with the divertor target plate and wall opens some of the field lines that were previously in the closed region inside the separatrix prior to the application of the n 1 magnetic perturbation field from the field-error correction coil although some field lines are always open due to intrinsic non-axisymmetric field errors without the correction coils . This topological change creates a set of highly complex field line trajectories that traverse the plasma volume inside the separatrix and connect the vertical high-field side HFS wall to the low-field side LFS horizontal divertor target plate. This topology is similar to that of line-tying found in the solar photosphere Gibons Spicer 1981 . Additionally the field line topology formed by this line-tying type of bifurcation is composed of a mixture of stochastic fields with a wide range of connection lengths Lc that form fractal distributions Abdullaev 2006 embedded inside a set of coherent flux tubes with short connection lengths Wingen et al. 2009b Wingen et al. 2009c . It is the short Lc flux tubes that play a fundamental role in the nonlinear ELM model discussed below. Fig. 5. a Full poloidal cross sectional view of a separatrix homoclinic tangle formed by an applied external n 1 magnetic perturbation due to the DIII-D field-error correction coil with a current of 8 kAt in discharge 133908 at t 2000 ms. b An expanded cross sectional view of the primary divertor. Lc is the field line connection length between the horizontal target plate z m and the vertical wall R m . The intersection of the homoclinic and heteroclinic lobes with divertor targets and walls forms objects referred to as magnetic footprints on the R ộ and z ộ planes of the divertor targets and walls respectively as shown in Fig. 6 a .
