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

Autor(es)

Martins, Caroline G. L. ^{[1, 2]} ; Roberto, M. ^[1] ; Caldas, I. L. ^[3]

Afiliação do(s) autor(es)

^[1] Inst Tecnol Aeronaut, Dept Fis, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[2] Univ Texas Austin, Inst Fus Studies, Dept Phys, Austin, TX 78712 - USA

^[3] Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physics of Plasmas; v. 21, n. 8 AUG 2014.
• Citações Web of Science: 2

Resumo

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 mapping to investigate stickiness alterations due to particle collisions. Within this model, we conclude that, even reduced by collisions, the observed trapping still influences the field line transport. The results obtained for our numerical estimations indicate that the reported trapping may affect the transport in present tokamaks. (C) 2014 AIP Publishing LLC. (AU)

• Processo FAPESP: 13/03401-6 - Transporte de linhas de campo magnético e de partículas em tokamaks e modelagem de plasmas para estudo de deposição e corrosão
• Beneficiário: Marisa Roberto
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/13162-0 - Topologia de Campos Magnéticos em Tokamaks
• Beneficiário: Caroline Gameiro Lopes Martins
• Modalidade de apoio: Bolsas no Brasil - Doutorado