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Abstract

The paper presents a new approach for the modelling of the pedestal energy transport in the presence of Type I ELMs based on the linear ideal MHD code MISHKA coupled with the non-linear energy transport code TELM in a realistic tokamak geometry. The main mechanism of increased transport through the External Transport Barrier (ETB) in this model of ELMs is the increased convective flux due to the MHD velocity perturbation and an additional conductive flux due the radial perturbation of the magnetic field leading to a flattening of the pressure profile in the unstable zone. The typical Type I ELM time-cycle including the destabilisation of the ballooning modes leading to the fast (200mu s) collapse of the pedestal pressure followed by the edge pressure profile re-building on a diffusive time scale was reproduced numerically. The possible mechanism of Type I ELMs control using a stochastic plasma boundary created by external coils is modelled in the paper. In the stochastic layer the transverse transport is effectively increased by the magnetic field line diffusion. The modelling results for DIII-D experiment on Type I ELM suppression using the external perturbation from the I-coils demonstrated the possibility to decrease the edge pressure gradient just under the ideal ballooning limit, leading to the high confinement regime without Type I ELMs.

Additional information

Authors: BECOULET M, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);HUYSMANS G, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);THOMAS P, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);GHENDRIH P, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);GROSMAN A, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);MONIER-GARBET P, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);GARBET X, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);ZWINGMAN W, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);NARDON E, Departement de Recherches sur la Fusion Controlee, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);MOYER R, University of California, San Diego, La Jolla (US);EVANS T, General Atomics, San Diego (US);LEONARD A, General Atomics, San Diego (US)
Bibliographic Reference: An oral paper given at: 20th IAEA Fusion Energy Conference Organised by: International Atomic Energy Agency Held at: Centrtro de Fusao Nuclear, Vilamoura (PT)
Availability: Available from Association EURATOM-CEA, Departement de Recherches sur la Fusion Controlee, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: dirdrfc@drfc.cad.cea.fr
Record Number: 200417825 / Last updated on: 2004-12-01
Category: PUBLICATION
Original language: en
Available languages: en