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Title: Fusion power production in International Thermonuclear Experimental Reactor baseline H-mode scenarios

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 4; Related Information: CHORUS Timestamp: 2016-12-26 04:37:53; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

Citation Formats

Rafiq, T., Kritz, A. H., Kessel, C. E., and Pankin, A. Y. Fusion power production in International Thermonuclear Experimental Reactor baseline H-mode scenarios. United States: N. p., 2015. Web. doi:10.1063/1.4917522.
Rafiq, T., Kritz, A. H., Kessel, C. E., & Pankin, A. Y. Fusion power production in International Thermonuclear Experimental Reactor baseline H-mode scenarios. United States. doi:10.1063/1.4917522.
Rafiq, T., Kritz, A. H., Kessel, C. E., and Pankin, A. Y. 2015. "Fusion power production in International Thermonuclear Experimental Reactor baseline H-mode scenarios". United States. doi:10.1063/1.4917522.
title = {Fusion power production in International Thermonuclear Experimental Reactor baseline H-mode scenarios},
author = {Rafiq, T. and Kritz, A. H. and Kessel, C. E. and Pankin, A. Y.},
abstractNote = {},
doi = {10.1063/1.4917522},
journal = {Physics of Plasmas},
number = 4,
volume = 22,
place = {United States},
year = 2015,
month = 4

Journal Article:
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Publisher's Version of Record at 10.1063/1.4917522

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  • Self-consistent simulations of 15 MA ITER H-mode DT scenarios, from ramp-up through flat-top, are carried out. Electron and ion temperatures, toroidal angular frequency, and currents are evolved, in simulations carried out using the predictive TRANSPort and integrated modeling code starting with initial profiles and equilibria obtained from tokamak simulation code studies. Studies are carried out examining the dependence and sensitivity of fusion power production on electron density, argon impurity concentration, choice of radio frequency heating, pedestal temperature without and with E × B flow shear effects included, and the degree of plasma rotation. The goal of these whole-device ITER simulationsmore » is to identify dependencies that might impact ITER fusion performance.« less
  • Experiments in Alcator C-Mod in (Enhanced D-alpha) EDA H-modes with extrinsic impurity seeding (N{sub 2}, Ne, and Ar) have demonstrated a direct correlation between plasma energy confinement and edge power flow, achieving values of H{sub 98{>=}} 1 for edge power flows only marginally exceeding the scaled power for access to H-mode confinement in these conditions. For lower Z impurity seeding (N{sub 2} and Ne), plasmas with high energy confinement are obtained with a radiative power fraction of 85% or larger and a reduction of the peak heat flux at the divertor by more than a factor of 5 compared tomore » similar attached conditions. The H-mode plasmas thus achieved in Alcator C-Mod meet or exceed the requirements both in terms of divertor heat flux handling and energy confinement for ITER Q{sub DT} = 10 operation and with an edge power flow only marginally above the H-mode threshold power (by 1.0-1.4) as expected in ITER.« less
  • The development of operating scenarios is one of the key issues in the research for ITER which aims to achieve a fusion gain (Q) of ∼10, while producing 500 MW of fusion power for ≥300 s. The ITER Research plan proposes a success oriented schedule starting in hydrogen and helium, to be followed by a nuclear operation phase with a rapid development towards Q ∼ 10 in deuterium/tritium. The Integrated Operation Scenarios Topical Group of the International Tokamak Physics Activity initiates joint activities among worldwide institutions and experiments to prepare ITER operation. Plasma formation studies report robust plasma breakdown in devices withmore » metal walls over a wide range of conditions, while other experiments use an inclined EC launch angle at plasma formation to mimic the conditions in ITER. Simulations of the plasma burn-through predict that at least 4 MW of Electron Cyclotron heating (EC) assist would be required in ITER. For H-modes at q{sub 95} ∼ 3, many experiments have demonstrated operation with scaled parameters for the ITER baseline scenario at n{sub e}/n{sub GW} ∼ 0.85. Most experiments, however, obtain stable discharges at H{sub 98(y,2)} ∼ 1.0 only for β{sub N} = 2.0–2.2. For the rampup in ITER, early X-point formation is recommended, allowing auxiliary heating to reduce the flux consumption. A range of plasma inductance (l{sub i}(3)) can be obtained from 0.65 to 1.0, with the lowest values obtained in H-mode operation. For the rampdown, the plasma should stay diverted maintaining H-mode together with a reduction of the elongation from 1.85 to 1.4. Simulations show that the proposed rampup and rampdown schemes developed since 2007 are compatible with the present ITER design for the poloidal field coils. At 13–15 MA and densities down to n{sub e}/n{sub GW} ∼ 0.5, long pulse operation (>1000 s) in ITER is possible at Q ∼ 5, useful to provide neutron fluence for Test Blanket Module assessments. ITER scenario preparation in hydrogen and helium requires high input power (>50 MW). H-mode operation in helium may be possible at input powers above 35 MW at a toroidal field of 2.65 T, for studying H-modes and ELM mitigation. In hydrogen, H-mode operation is expected to be marginal, even at 2.65 T with 60 MW of input power. Simulation code benchmark studies using hybrid and steady state scenario parameters have proved to be a very challenging and lengthy task of testing suites of codes, consisting of tens of sophisticated modules. Nevertheless, the general basis of the modelling appears sound, with substantial consistency among codes developed by different groups. For a hybrid scenario at 12 MA, the code simulations give a range for Q = 6.5–8.3, using 30 MW neutral beam injection and 20 MW ICRH. For non-inductive operation at 7–9 MA, the simulation results show more variation. At high edge pedestal pressure (T{sub ped} ∼ 7 keV), the codes predict Q = 3.3–3.8 using 33 MW NB, 20 MW EC, and 20 MW ion cyclotron to demonstrate the feasibility of steady-state operation with the day-1 heating systems in ITER. Simulations using a lower edge pedestal temperature (∼3 keV) but improved core confinement obtain Q = 5–6.5, when ECCD is concentrated at mid-radius and ∼20 MW off-axis current drive (ECCD or LHCD) is added. Several issues remain to be studied, including plasmas with dominant electron heating, mitigation of transient heat loads integrated in scenario demonstrations and (burn) control simulations in ITER scenarios.« less
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  • The evolution of the plasma temperature and density in an international thermonuclear experimental reactor (ITER)-like fusion device has been studied by numerically solving the energy transport equation coupled with the particle transport equation. The effect of particle pinch, which depends on the magnetic curvature and the safety factor, has been taken into account. The plasma is primarily heated by the alpha particles which are produced by the deuterium-tritium fusion reactions. A semi-empirical method, which adopts the ITERH-98P(y,2) scaling law, has been used to evaluate the transport coefficients. The fusion performances (the fusion energy gain factor, Q) similar to the ITERmore » inductive scenario and non-inductive scenario (with reversed magnetic shear) are obtained. It is shown that the particle pinch has significant effects on the fusion performance and profiles of a fusion reactor. When the volume-averaged density is fixed, particle pinch can lower the pedestal density by ∼30%, with the Q value and the central pressure almost unchanged. When the particle source or the pedestal density is fixed, the particle pinch can significantly enhance the Q value by  60%, with the central pressure also significantly raised.« less