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Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on BT

Journal Article · · Nuclear Fusion
 [1];  [2];  [3]; ;  [2];  [2];  [2];  [2];  [2];  [4];  [2];  [2];  [2];  [5]
  1. Vienna Univ. of Technology (Austria); OSTI
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  3. Max Planck Society, Garching (Germany)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Fircroft Engineering (United Kingdom)
+ Show Author Affiliations
Here, in this paper, we investigate the role of the edge ion heat flux for transitions from L-mode to H-mode in Alcator C-Mod. Previous results from the ASDEX Upgrade tokamak indicated that a critical value of edge ion heat flux per particle is needed for the transition. Analysis of C-Mod data confirms this result. The edge ion heat flux is indeed found to increase linearly with density at given magnetic field and plasma current. Furthermore, the Alcator C-Mod data indicate that the edge ion heat flux at the L-H transition also increases with magnetic field. Combining the data from Alcator C-Mod and ASDEX Upgrade yields a general expression for the edge ion heat flux at the L-H transition. These results are discussed from the point of view of the possible physics mechanism of the L-H transition. They are also compared to the L-H power threshold scaling and an extrapolation for ITER is given.
Research Organization:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
Sponsoring Organization:
European Atomic Energy Community (Euratom); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Contributing Organization:
ASDEX Upgrade Team; Alcator C-Mod Team
Grant/Contract Number:
FC02-99ER54512; SC0014264
OSTI ID:
1895310
Alternate ID(s):
OSTI ID: 22925535
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 5 Vol. 58; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (2)

Safety factor and turbulence dynamics dependence of the L-H power threshold on DIII-D journal June 2019
Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks journal March 2019

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Alcator C-Mod
L-H transition
power threshold