Approaching Detachment in I-mode - Response of Core Confinement and the Edge Pedestal in the ASDEX Upgrade Tokamak

Experiments on nitrogen assisted divertor detachment in the improved energy confinement mode (I-mode) are reported from the ASDEX Upgrade tokamak. When nitrogen is introduced into the divertor and radiation losses cool the divertor plasma down, a loss of core confinement is observed, concomitant wit...

Descripción completa

Detalles Bibliográficos
Autores: Happel, T. , Reinke, M. L., Silvagni, D., Bernert, M., Grover, O., Hennequin, P., Hubbard, A. E., Plank, U., Trier, E., Brida, D., Viezzer, Eleonora
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2021
País:España
Institución:Universidad de Sevilla (US)
Repositorio:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/141183
Acceso en línea:https://hdl.handle.net/11441/141183
https://doi.org/10.1088/1741-4326/abd7b7
Access Level:acceso abierto
Palabra clave:Confinement Regime
Detachment
ELM-free
I-mode
Nitrogen seeding
Tokamak
Descripción
Sumario:Experiments on nitrogen assisted divertor detachment in the improved energy confinement mode (I-mode) are reported from the ASDEX Upgrade tokamak. When nitrogen is introduced into the divertor and radiation losses cool the divertor plasma down, a loss of core confinement is observed, concomitant with an increase in low frequency edge fluctuation levels. The loss in confinement can be compensated and the I-mode can be maintained by additional heating power input. Detachment of the inner divertor leg has been observed for the first time in an I-mode discharge. The outer divertor leg remains attached in these experiments. Good energy confinement properties (H 98(y, 2) = 0.9) during the detachment of the inner divertor leg are reported.