Pellet-fueled I-mode plasmas in ASDEX Upgrade

Nuclear Fushion

article

D. Silvagni¹  P.T. Lang¹  T. Happel¹  A. Bock¹  R. Fischer¹  L. Gil²  O.J.W.F. Kardaun¹  R.M. McDermott¹  U. Plank¹  B. Plöckl¹  D. Stieglitz¹  G. Tardini¹ 

[1] Max-Planck-Institut für Plasmaphysik;Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa

关键词: I-mode;    pellet;    energy confinement time;    tokamak;    fueling;    DEMO;   

DOI  :  10.1088/1741-4326/acde8c

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

This letter reports on the efforts carried out at the ASDEX Upgrade tokamak to integrate I-mode plasmas with pellet fueling and to increase the I-mode Greenwald fraction f_{mathrm{GW}} , two important requirements for any DEMO operational scenario. For the first time, stationary I-mode plasmas have been achieved with pellet fueling and the core Greenwald fraction has been increased up to 0.8. Larger f_{mathrm{GW}}were not achieved due to technical constraints rather than to a physics-based limit. Pellet-fueled I-mode plasmas exhibit enhanced core and edge density, while core and edge temperature are reduced. Nonetheless, edge normalized gradients remain I-mode-like, namely shallow for the density and steep for the temperature. The I-mode energy confinement time is found to obey two distinct density dependencies: for f_{mathrm{GW}}lt0.4it rises with increasing f_{mathrm{GW}} , while for f_{mathrm{GW}} gt 0.4the energy confinement time plateaus with increasing f_{mathrm{GW}} , or even decreases with f_{mathrm{GW}}for the pellet-fueled plasmas. Similarities with Ohmic and L-mode energy confinement time dependency on density are discussed.

【 授权许可】

Unknown