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Title: Examination of the Entry to Burn and Burn Control for the ITER 15 MA Baseline and Other Scenarios

Abstract

The entry to burn and flattop burn control in ITER will be a critical need from the first DT experiments. Simulations are used to address time-dependent behavior under a range of possible conditions that include injected power level, impurity content (W, Ar, Be), density evolution, H-mode regimes, controlled parameter (Wth, Pnet, Pfusion), and actuator (Paux, fueling, fAr), with a range of transport models. A number of physics issues at the L-H transition require better understanding to project to ITER, however, simulations indicate viable control with sufficient auxiliary power (up to 73 MW), while lower powers become marginal (as low as 43 MW).

Authors:
 [1];  [2];  [3]
  1. PPPL
  2. ITER
  3. EURATOM-OAW/ATI
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
Princeton Plasma Physics Laboratory, Princeton, NJ USA; EURATOM-OAW/ATI, Atominstitut, TU-Wein, Vienna, Austria; NRC Kurchatov Institute, Moscow, Russia
OSTI Identifier:
1182599
Report Number(s):
PPPL-5069
DOE Contract Number:
DE-AC02-09CH11466
Resource Type:
Conference
Resource Relation:
Conference: 25th IAEA Fusion Energy Conference, St. Petersburg, Russia, 13-18 October 2014.
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Fusion power; Numerical Simulation; Tokamaks

Citation Formats

Kesse, Charles E., Kim, S-H., and Koechl, F. Examination of the Entry to Burn and Burn Control for the ITER 15 MA Baseline and Other Scenarios. United States: N. p., 2014. Web.
Kesse, Charles E., Kim, S-H., & Koechl, F. Examination of the Entry to Burn and Burn Control for the ITER 15 MA Baseline and Other Scenarios. United States.
Kesse, Charles E., Kim, S-H., and Koechl, F. Mon . "Examination of the Entry to Burn and Burn Control for the ITER 15 MA Baseline and Other Scenarios". United States. doi:. https://www.osti.gov/servlets/purl/1182599.
@article{osti_1182599,
title = {Examination of the Entry to Burn and Burn Control for the ITER 15 MA Baseline and Other Scenarios},
author = {Kesse, Charles E. and Kim, S-H. and Koechl, F.},
abstractNote = {The entry to burn and flattop burn control in ITER will be a critical need from the first DT experiments. Simulations are used to address time-dependent behavior under a range of possible conditions that include injected power level, impurity content (W, Ar, Be), density evolution, H-mode regimes, controlled parameter (Wth, Pnet, Pfusion), and actuator (Paux, fueling, fAr), with a range of transport models. A number of physics issues at the L-H transition require better understanding to project to ITER, however, simulations indicate viable control with sufficient auxiliary power (up to 73 MW), while lower powers become marginal (as low as 43 MW).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}

Conference:
Other availability
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  • Experiments on Alcator C-Mod have addressed several issues for the ITER 15 MA baseline scenario from 2009-2012. Rampup studies show ICRF can save significant V-s, and that an H-mode in the ramp can be utilized to save 50% more. ICRF modifications to li(1) are minimal, although the Te profile is peaked relative to ohmic in the plasma center, and alter sawtooth onset times. Rampdown studies show H-modes can be routinely sustained, avoiding an OH coil over-current associated with the H-L transition, that fast rampdowns are preferred, the density drops with Ip, and that the H-L transition occurs at Ploss/Pthr,LH ~more » 1.0-1.3 at n/nGr ~ 0.85. Flattop plasmas targeting ITER baseline parameters have been sustained for 20 τE or 8-13 τCR, but only reach H98 ~ 0.6 at n/nGr = 0.85, rising to 0.9 at n/nGr = 0.65.« less
  • Reference operating scenarios for the physics phase of the International Thermonuclear Experimental Reactor (ITER) rely on low temperature, high density operation for good divertor performance. Operating points in this region are usually thermally unstable and active burn control is required to maintain operation at the selected operating point. We present a series of transport simulations of ITER burn control scenarios with modulated neutral beam heating, using the 1-1/2D code WHIST. Our results indicate that control is possible, except at very high densities ({l angle}n{sub e}{r angle} {ge} 1.80{times}10{sup 20} m{sup {minus}3}) where off-axis heating due to the poor beam penetrationmore » makes control difficult, especially for negative perturbations 15 refs., 20 figs.« less
  • The poloidal field (PF) coil system on ITER, which provides both feedforward and feedback control of plasma position, shape, and current, is a critical element for achieving mission performance. Analysis of PF capabilities has focused on the 15 MA Q = 10 scenario with a 300-500 s flattop burn phase. The operating space available for the 15 MA ELMy H-mode plasma discharges in ITER and upgrades to the PF coils or associated systems to establish confidence that ITER mission objectives can be reached have been identified. Time dependent self-consistent free-boundary calculations were performed to examine the impact of plasma variability,more » discharge programming, and plasma disturbances. Based on these calculations a new reference scenario was developed based upon a large bore initial plasma, early divertor transition, low level heating in L-mode, and a late H-mode onset. Equilibrium analyses for this scenario indicate that the original PF coil limitations do not allow low li (<0.8) operation or lower flux states, and the flattop burn durations were predicted to be less than the desired 400 s. This finding motivates the expansion of the operating space, considering several upgrade options to the PF coils. Analysis was also carried out to examine the feedback current reserve required in the CS and PF coils during a series of disturbances and a feasibility assessment of the 17 MA scenario was undertaken. Results of the studies show that the new scenario and modified PF system will allow a wide range of 15 MA 300-500 s operation and more limited but finite 17 MA operation.« less
  • OAK A271 DEMONSTRATION IN THE DIII-D TOKAMAK OF AN ALTERNATE BASELINE SCENARIO FOR ITER AND OTHER BURNING PLASMA EXPERIMENTS. Discharges which can satisfy the high gain goals of burning plasma experiments have been demonstrated in the DIII-D tokamak in stationary conditions with relatively low plasma current (q{sub 95} > 4). A figure of merit for fusion gain {Beta}{sub N}H{sub 89}/q{sub 95}{sup 2} has been maintained at values corresponding to Q = 10 operation in a burning plasma for > 6 s or 36 {tau}{sub E} and 2 {tau}{sub R}. The key element is the relaxation of the current profile tomore » a stationary state with q{sub min} > 1, which allows stable operation up to the no-wall ideal {beta} limit. These plasmas maintain particle balance by active pumping rather than transient wall conditions. The reduced current lessens significantly the potential for structural damage in the event of a major disruption.« less
  • Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. The two baseline strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed tomore » highlight the needed community R & D. In addition, recent progress in ELM-free regimes, namely Quiescent H-mode, I-mode, and Enhanced Pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes.« less