Plasma Scenario Study for HT-6M Tokamak Using BALDUR Integrated Predictive Modeling Code (original) (raw)

Simulations of ITB H-Mode Tokamak Plasmas with Predictive Toroidal Velocity Model

2010

A model for predicting toroidal velocity in H-mode tokamak plasma after neutral beam heating is turned on is implemented in an integrated predictive modelling code BALDUR in order to self-consistently simulate the time-evolution of plasma current, temperature, and density profiles in tokamaks. In this model, the toroidal velocity is developed according to a theory of electromagnetism in which the toroidal velocity can be obtained from a current density flow in toroidal direction. The core transport model used in these simulations is a combination of a neoclassical transport model called NCLASS, and an anomalous transport model, semi-empirical Mixed Bohm/gyro-Bohm (Mixed B/gB) that includes ITB effects. The boundary condition of the plasma is assumed to be at the top of the pedestal. The pedestal temperature is calculated using a theory-based pedestal model which is based on a combination of magnetic and flow shear stabilization pedestal width scaling and an infinite-n ballooning pre...

Integrated predictive modeling simulations of the Mega-Amp Spherical Tokamak

Physics of Plasmas, 2002

Integrated predictive modeling simulations are carried out using the BALDUR transport code ͓Singer et al., Comput. Phys. Commun. 49, 275 ͑1982͔͒ for high confinement mode ͑H-mode͒ and low confinement mode ͑L-mode͒ discharges in the Mega-Amp Spherical Tokamak ͑MAST͒ ͓Sykes et al., Phys. Plasmas 8, 2101 ͑2001͔͒. Simulation results, obtained using either the Multi-Mode transport model ͑MMM95͒ or, alternatively, the mixed-Bohm/gyro-Bohm transport model, are compared with experimental data. In addition to the anomalous transport, neoclassical transport is included in the simulations and the ion thermal diffusivity in the inner third of the plasma is found to be predominantly neoclassical. The sawtooth oscillations in the simulations radially spread the neutral beam injection heating profiles across a broad sawtooth mixing region. The broad sawtooth oscillations also flatten the central temperature and electron density profiles. Simulation results for the electron temperature and density profiles are compared with experimental data to test the applicability of these models and the BALDUR integrated modeling code in the limit of low aspect ratio toroidal plasmas.

Comparisons and Physics Basis of Tokamak Transport Models and Turbulence Simulations

2000

The predictions of gyrokinetic and gyro∞uid simulations of ion-temperature-gradient (ITG) instability and turbulence in tokamak plasmas as well as some tokamak plasma thermal transport models, which have been widely used for predicting the performance of the proposed ITER tokamak, are compared. These comparisons provide information on efiects of difierences in the physics content of the various models and on the

Plasma simulator METIS for tokamak confinement and heating studies

Parallel Computing, 1992

To fill up a theoretical database necessary for the fusion reactor development of program a plasma simulator METIS was designed and a prototype plasma simulator ProtoMETIS was constructed. METIS is projected on the basis of a MIMD type parallel computer composed of 250 processor elements with distributed memories and optimized for analyses of the nonlinear MHD behavior of a plasma and the loss of alpha particles due to magnetic field ripples in a tokamak. By using ProtoMETIS performance of the METIS architecture was investigated for the above problems and satisfactory results were attained. It was also confirmed that a simulation of a free electron laser used for plasma heating and an MHD equilibrium computation of a tokamak plasma were carried out efficiently on the plasma simulator.

Modeling of the shear effects on the thermal ion transport in advanced tokamak scenarios

Physics of Plasmas, 1999

Plasma shear effects on thermal ion transport in present advanced tokamak scenarios are analyzed. In order to overcome some limitations encountered from previous shear dependent models ͓e.g., V. Parail et al., Plasma Phys. Controlled Fusion 40, 805 ͑1998͒, and references therein͔, a semiempirical model combining the effects of the magnetic and EϫB rotation shears is proposed. These shear dependences are based on simple theoretical arguments from turbulence studies. The dominant stabilizing term of our shear correction is the shear in toroidal rotation. The predictive modeling of the formation and evolution of thermal ion internal transport barriers in relevant advanced scenarios of Tokamak Fusion Test Reactor ͓E. J. Synakowski et al., Phys. Plasmas 4, 1736 ͑1997͔͒, Doublet III-D ͑DIII-D͒ ͓B. W. Rice et al., Nucl. Fusion 36, 1271 ͑1996͔͒ and Joint European Torus ͑JET͒ ͓F. X. Söldner and the JET Team, Plasma Phys. Controlled Fusion 39, B353 ͑1997͔͒ with our shear correction is presented. A multimachine test of the model performed here provides a basis for predictive simulations of future experiments and for the optimization of advanced scenarios through plasma control.

Simulation of the Plasma Density Evolution during Electron Cyclotron Resonance Heating at the T-10 Tokamak

Plasma Physics Reports, 2018

In ohmically heated (OH) plasma with low recycling, an improved particle confinement (IPC) mode is established during gas puffing. However, after gas puffing is switched off, this mode is retained only for about 100 ms, after which an abrupt phase transition into the low particle confinement (LPC) mode occurs in the entire plasma cross section. During such a transition, energy transport due to heat conduction does not change. The phase transition in OH plasma is similar to the effect of density pump-out from the plasma core, which occurs after electron cyclotron heating (ECH) is switched on. Analysis of the measured plasma pressure profiles in the T-10 tokamak shows that, after gas puffing in the OH mode is switched off, the plasma pressure profile in the IPC stage becomes more peaked and, after the peakedness exceeds a certain critical value, the IPC−LPC transition occurs. Similar processes are also observed during ECH. If the pressure profile is insufficiently peaked during ECH, then the density pump-out effect comes into play only after the critical peakedness of the pressure profile is reached. In the plasma core, the density and pressure profiles are close to the corresponding canonical profiles. This allows one to derive an expression for the particle flux within the canonical profile model and formulate a criterion for the IPC−LPC transition. The time evolution of the plasma density profile during phase transitions was simulated for a number of T-10 shots with ECH and high recycling. The particle transport coefficients in the IPC and LPC phases, as well as the dependences of these coefficients on the ECH power, are determined.

Quantitative predictions of tokamak energy confinement from first-principles simulations with kinetic effects

Physics of Plasmas, 1995

A rst-principles model of anomalous thermal transport based on numerical simulations is presented, with stringent comparisons to experimental data from the Tokamak Fusion Test Reactor (TFTR) Fusion Technol. 21, 1324 (1992)]. This model is based on nonlinear gyro uid simulations, which predict the uctuation and thermal transport characteristics of toroidal iontemperature-gradient-driven (ITG) turbulence, and on comprehensive linear gyrokinetic ballooning calculations, which provide very accurate growth rates, critical temperature gradients, and a quasilinear estimate of e = i . The model is derived solely from the simulation results. More than 70 TFTR low connement (L-mode) discharges have been simulated with quantitative success.

Advanced transport modelling in tokamak plasmas

2018

In this work an integrated modelling of L-mode tokamak plasmas with a theory-based transport model is implemented to investigate the mechanisms of widely observed phenomena: energy confinement time saturation and reversals of plasma intrinsic toroidal rotation. A consistent physical picture is proposed, involving an interplay between the impurity concentration, turbulence regime and other plasma parameters. The profile shearing effect is confirmed to dominate the intrinsic rotation mechanism.

RITM-Code Modelling of Plasmas with Edge Transport Barrier

Contributions to Plasma Physics, 2006

Conditions for the formation of the edge transport barrier (ETB) in tokamaks are investigated by means of onedimensional transport modeling performed for the characteristic parameter range of the TEXTOR tokamak. The computations predict the formation of the ETB at the heating power given by the multi-machine scaling if the fraction of convective heat losses from the plasma does not exceed 50%. An increase of the amount of heat lost through convection above this critical value shifts the formation of ETB to a power several times above the level given by the scaling. For given plasma parameters, the ratio of the conductive to convective heat losses at the plasma edge is determined by the penetration of neutrals. By switching from a divertor to a limiter configuration when the distance between the LCMS and neutralizing plates decreases, this ratio increases due to the higher fraction of particles ionized inside the last closed magnetic surface (LCMS). This can be the reason for the higher H-mode power threshold in limiter tokamaks. First experimental results obtained in TEXTOR demonstrate a good agreement of the power required for ETB formation with the value calculated with 1.5D transport code RITM prior to the experiment.