Current ramps in tokamaks: from present experiments to ITER scenarios
- 14 July 2011
- journal article
- research article
- Published by IOP Publishing in Nuclear Fusion
Abstract
In order to prepare adequate current ramp-up and ramp-down scenarios for ITER, present experiments from various tokamaks have been analysed by means of integrated modelling in view of determining relevant heat transport models for these operation phases. A set of empirical heat transport models for L-mode (namely, the Bohm-gyroBohm model and scaling based models with a specific fixed radial shape and energy confinement time factors of H96-L = 0.6 or H-IPB98 = 0.4) has been validated on a multi-machine experimental dataset for predicting the l(i) dynamics within +/- 0.15 accuracy during current ramp-up and ramp-down phases. Simulations using the Coppi-Tang or GLF23 models (applied up to the LCFS) overestimate or underestimate the internal inductance beyond this accuracy (more than +/- 0.2 discrepancy in some cases). The most accurate heat transport models are then applied to projections to ITER current ramp-up, focusing on the baseline inductive scenario (main heating plateau current of I-p = 15 MA). These projections include a sensitivity study to various assumptions of the simulation. While the heat transport model is at the heart of such simulations (because of the intrinsic dependence of the plasma resistivity on electron temperature, among other parameters), more comprehensive simulations are required to test all operational aspects of the current ramp-up and ramp-down phases of ITER scenarios. Recent examples of such simulations, involving coupled core transport codes, free-boundary equilibrium solvers and a poloidal field (PF) systems controller are also described, focusing on ITER current ramp-down.This publication has 14 references indexed in Scilit:
- The CRONOS suite of codes for integrated tokamak modellingNuclear Fusion, 2010
- Development of ITER 15 MA ELMy H-mode inductive scenarioNuclear Fusion, 2009
- Integrated modelling of ITER reference scenariosNuclear Fusion, 2009
- Lower hybrid assisted plasma current ramp-up in ITERPlasma Physics and Controlled Fusion, 2009
- Ray-tracing and Fokker–Planck modelling of the effect of plasma current on the propagation and absorption of lower hybrid wavesPlasma Physics and Controlled Fusion, 2005
- Chapter 1: Overview and summaryNuclear Fusion, 1999
- Validation of a new mixed Bohm/gyro-Bohm model for electron and ion heat transport against the ITER, Tore Supra and START database dischargesNuclear Fusion, 1998
- ITER L mode confinement databaseNuclear Fusion, 1997
- A gyro-Landau-fluid transport modelPhysics of Plasmas, 1997
- TSC simulation of Ohmic discharges in TFTRNuclear Fusion, 1993