Analysis and Modeling of DIII-D Hybrid Discharges and their Extrapolation to ITER Metadata

Title

• Main Title Analysis and Modeling of DIII-D Hybrid Discharges and their Extrapolation to ITER

Creator

• Author: Makowski, M. A.
  Creator Type: Personal
• Author: Casper, T. A.
  Creator Type: Personal
• Author: Jayakumar, R. J.
  Creator Type: Personal
• Author: Pearlstein, L. D.
  Creator Type: Personal
• Author: Petty, C. C.
  Creator Type: Personal
• Author: Wade, M. R.
  Creator Type: Personal

Contributor

• Sponsor: United States. Department of Energy.
  Contributor Type: Organization

Publisher

• Name: Lawrence Livermore National Laboratory
  Place of Publication: Livermore, California
  Additional Info: Lawrence Livermore National Laboratory (LLNL), Livermore, CA

Date

• Creation: 2006-06-16

Language

• English

Description

• Content Description: Recent experiments on tokamaks around the world [1-5] have demonstrated discharges with moderately high performance in which the q-profile remains stationary, as measured by the motional Stark effect diagnostic, for periods up to several {tau}{sub R}. Hybrid discharges are characterize by q{sub min} {approx} 1, high {beta}{sub N}, and good confinement. These discharges have been termed hybrid because of their intermediate nature between that of an ordinary H-mode and advanced tokamak discharges. They form an attractive scenario for ITER as the normalized fusion performance ({beta}{sub N}H{sub 89P}/q{sub 95}{sup 2}) is at or above that for the ITER baseline Q{sub fus} = 10 scenario, even for q{sub 95} as high as 4.6. The startup phase is thought to be crucial to the ultimate evolution of the hybrid discharge. An open question is how hybrid discharges achieve and maintain their stationary state during the initial startup phase. To investigate this aspect of hybrid discharges, we have used the CORSICA code to model the early stages of a discharge. Results clearly indicate that neoclassical current evolution alone is insufficient to account for the time evolution of the q-profile and that an addition of non-inductive current source must be incorporated into the model to reproduce the experimental time history. We include non-inductive neutral beam and bootstrap current sources in the model, and investigate the difference between simulations with these sources and the experimentally inferred q-profile. Further, we have made preliminary estimates of the spatial structure of the current needed to bring the simulation and experiment into agreement. This additional non-inductive source has not been tied to any physical mechanism as yet. We present these results and discuss the implications for hybrid startup on ITER.
• Physical Description: PDF-file: 6 pages; size: 0.7 Mbytes

Subject

• Keyword: Bootstrap Current
• STI Subject Categories: 70 Plasma Physics And Fusion Technology
• Keyword: Doublet-3 Device
• Keyword: Simulation
• Keyword: Extrapolation
• Keyword: Physics
• Keyword: Confinement
• Keyword: Plasma
• Keyword: Performance
• Keyword: Stark Effect

Source

• Conference: Presented at: 33rd European Physical Society Conference on Plasma Physics, Rome, Italy, Jun 19 - Jun 23, 2006

Collection

• Name: Office of Scientific & Technical Information Technical Reports
  Code: OSTI

Institution

• Name: UNT Libraries Government Documents Department
  Code: UNTGD

Resource Type

• Article

Format

• Text

Identifier

• Report No.: UCRL-CONF-222187
• Grant Number: W-7405-ENG-48
• Office of Scientific & Technical Information Report Number: 896584
• Archival Resource Key: ark:/67531/metadc884474