The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library
TL;DR: The NUBEAM module as mentioned in this paper is a comprehensive computational model for Neutral Beam Injection (NBI) in tokamaks, which is used to compute power deposition, driven current, momentum transfer, fueling, and other profiles.
About: This article is published in Computer Physics Communications.The article was published on 2004-06-01. It has received 636 citations till now.
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TL;DR: The actuators for heating and current drive that are necessary to produce and control the advanced tokamak discharges are discussed, including modelling and predictions for ITER, and specific control issues for steady state operation are discussed.
Abstract: Significant progress has been made in the area of advanced modes of operation that are candidates for achieving steady state conditions in a fusion reactor. The corresponding parameters, domain of operation, scenarios and integration issues of advanced scenarios are discussed in this chapter. A review of the presently developed scenarios, including discussions on operational space, is given. Significant progress has been made in the domain of heating and current drive in recent years, especially in the domain of off-axis current drive, which is essential for the achievement of the required current profile. The actuators for heating and current drive that are necessary to produce and control the advanced tokamak discharges are discussed, including modelling and predictions for ITER. The specific control issues for steady state operation are discussed, including the already existing experimental results as well as the various strategies and needs (qψ profile control and temperature gradients). Achievable parameters for the ITER steady state and hybrid scenarios with foreseen heating and current drive systems are discussed using modelling including actuators, allowing an assessment of achievable current profiles. Finally, a summary is given in the last section including outstanding issues and recommendations for further research and development.
327 citations
TL;DR: The framework made possible the design and automation of a workflow that enables self-consistent predictions of kinetic profiles and the plasma equilibrium, and it was found that the feedback between the transport fluxes and plasma equilibrium can significantly affect the kinetic profiles predictions.
Abstract: One modeling framework for integrated tasks (OMFIT) is a comprehensive integrated modeling framework which has been developed to enable physics codes to interact in complicated workflows, and support scientists at all stages of the modeling cycle. The OMFIT development follows a unique bottom-up approach, where the framework design and capabilities organically evolve to support progressive integration of the components that are required to accomplish physics goals of increasing complexity. OMFIT provides a workflow for easily generating full kinetic equilibrium reconstructions that are constrained by magnetic and motional Stark effect measurements, and kinetic profile information that includes fast-ion pressure modeled by a transport code. It was found that magnetic measurements can be used to quantify the amount of anomalous fast-ion diffusion that is present in DIII-D discharges, and provide an estimate that is consistent with what would be needed for transport simulations to match the measured neutron rates. OMFIT was used to streamline edge-stability analyses, and evaluate the effect of resonant magnetic perturbation (RMP) on the pedestal stability, which have been found to be consistent with the experimental observations. The development of a five-dimensional numerical fluid model for estimating the effects of the interaction between magnetohydrodynamic (MHD) and microturbulence, and its systematic verification against analytic models was also supported by the framework. OMFIT was used for optimizing an innovative high-harmonic fast wave system proposed for DIII-D. For a parallel refractive index , the conditions for strong electron-Landau damping were found to be independent of launched and poloidal angle. OMFIT has been the platform of choice for developing a neural-network based approach to efficiently perform a non-linear multivariate regression of local transport fluxes as a function of local dimensionless parameters. Transport predictions for thousands of DIII-D discharges showed excellent agreement with the power balance calculations across the whole plasma radius and over a broad range of operating regimes. Concerning predictive transport simulations, the framework made possible the design and automation of a workflow that enables self-consistent predictions of kinetic profiles and the plasma equilibrium. It is found that the feedback between the transport fluxes and plasma equilibrium can significantly affect the kinetic profiles predictions. Such a rich set of results provide tangible evidence of how bottom-up approaches can potentially provide a fast track to integrated modeling solutions that are functional, cost-effective, and in sync with the research effort of the community.
234 citations
TL;DR: In this paper, a multi-dimensional code suite with physics-based models, self-consistent steady-state and hybrid mode scenarios for CFETR have been developed under a high magnetic field up to 6.5 T. Subsequently the engineering design of CFETr including the magnet system, vacuum system, tritium breeding blanket, divertor, remote handling and maintenance system.
Abstract: The Chinese Fusion Engineering Testing Reactor (CFETR), complementing the ITER facility, is aiming to demonstrate fusion energy production up to 200 MW initially and to eventually reach DEMO relevant power level 1 GW, to manifest a high duty factor of 0.3–0.5, and to pursue tritium self-sufficiency with tritium breeding ratio (TBR) >1. The key challenge to meet the missions of the CFETR is to run the machine in steady state (or long pulse) and high duty factor. By using a multi-dimensional code suite with physics-based models, self-consistent steady-state and hybrid mode scenarios for CFETR have been developed under a high magnetic field up to 6.5 T. The negative-ion neutral beam injection together with high frequency electron cyclotron wave and lower hybrid wave (and/or fast wave) are proposed to be used to drive the current. Subsequently the engineering design of CFETR including the magnet system, vacuum system, tritium breeding blanket, divertor, remote handling and maintenance system will be introduced. Some research and development (R&D) activities are also introduced in this paper.
225 citations
TL;DR: A complete reimplementation of the well-established minority species code ASCOT is carried out as a response both to the increase in computing power during the last twenty years and to the weakly structured growth of the code, which has made implementation of additional models impractical.
159 citations
Cites methods from "The tokamak Monte Carlo fast ion mo..."
...For the beam-beam reaction the fusion cross section is first averaged over the gyro angle χ in a similar way that NUBEAM [43, 44] does in order to get the averaged reactivity 〈σv〉BB (vi⊥, v j⊥, |vi|| − v j||...
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...For the beam-beam reaction the fusion cross section is first averaged over the gyro angle χ in a similar way that NUBEAM [43, 44] does in order to get the averaged reactivity...
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TL;DR: In this article, a code that predicts the efflux to a neutral particle analyzer (NPA) diagnostic and the photon radiance of Balmer-alpha light to a fast ion Dα (FIDA) diagnostic is described.
Abstract: A code that models signals produced by charge-exchange reactions between fast ions and injected neutral beams in tokamak plasmas is described. With the fast- ion distribution function as input, the code predicts the efflux to a neutral particle analyzer (NPA) diagnostic and the photon radiance of Balmer-alpha light to a fast- ion Dα (FIDA) diagnostic. Reactions with both the primary injected neutrals and with the cloud of secondary "halo" neutrals that surround the beam are treated. Accurate calculation of the fraction of neutrals that occupy excited atomic states (the collisional- radiative transition equations) is an important element of the code. Comparison with TRANSP output and other tests verify the solutions. Judicious selection of grid size and other parameters facilitate efficient solutions. The output of the code has been validated by FIDA measurements on DIII-D but further tests are warranted.
125 citations
References
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01 Jan 1987
721 citations
"The tokamak Monte Carlo fast ion mo..." refers background or methods in this paper
...The impurity stopping data has known deficiencies [22], and a collaboration w Oak Ridge atomic data center is under way to upgrade the available cross sections, which will be reflec future version of PREACT....
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...As with neutral beam deposition, a “constant census” al is used: a population ofnptclf Monte Carlo model ions of roughly equal weight is maintained for each fusio product species....
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TL;DR: In this article, the authors identify the internal disruption as a growing sinusoidal $m=1$, $n=1$ oscillation and compare the properties of these oscillations with predictions for the $m = 1$ internal kink mode.
Abstract: Fluctuations in x-ray intensity from the ST tokamak show a characteristic sawtooth behavior. This behavior is identified as an internal disruption. The internal disruptions are preceded by growing sinusoidal $m=1$, $n=1$ oscillations. The properties of these oscillations are compared with predictions for the $m=1$ internal kink mode.
623 citations
TL;DR: In this paper, a set of numerical techniques for calculating heat and particle source rates due to neutral beam injection in axisymmetric tokamaks is described, taking into account a number of significant, and normally neglected, effects.
518 citations
TL;DR: In this article, a Hamiltonian guiding center drift orbit formalism was developed for particle trajectories in magnetic field configurations of arbitrary cross section with arbitrary plasma β, where the magnetic field is assumed to be a small perturbation from a zero-order "equilibrium" field possessing magnetic surfaces.
Abstract: A Hamiltonian guiding center drift orbit formalism is developed which permits the efficient calculation of particle trajectories in magnetic field configurations of arbitrary cross section with arbitrary plasma β. The magnetic field is assumed to be a small perturbation from a zero‐order ‘‘equilibrium’’ field possessing magnetic surfaces. The equilibrium field, possessing helical or toroidal symmetry, can be modeled analytically or obtained numerically from equilibrium codes. The formalism is used to study trapped particle precession. Finite banana width corrections to the toroidal precession rate are derived, and the bounce averaged trapped particle motion is expressed in Hamiltonian form. Particle drift‐pumping associated with the ‘‘fishbone’’ oscillation is investigated. A numerical code based on the formalism is used to study particle orbits in circular and bean‐shaped tokamak configurations.
462 citations