In this talk, we highlight two analysis tools for evaluating fusion simulations. The first tool i... more In this talk, we highlight two analysis tools for evaluating fusion simulations. The first tool is for interactively exploring the topology of the magnetic field using a Poincaré map. Unlike traditional Poincaré maps that rely on a dense set of puncture points to form a contiguous representation of the magnetic surface we use a sparse set of connected puncture points. The puncture points are connected based on a rational approximation of the safety factor. The resulting analysis not only allows for the visualization of magnetic surfaces using a minimal number of puncture points but also identifies features such as magnetic islands. The second tool is for performing query based analysis on simulations utilizing particles. To assist in the analysis of simulation codes that utilize millions to billions of particles we have developed analysis tools that combine parallel coordinates plots combine with accelerated index searches. Parallel coordinate plots allow one to identify trends with...
MHD Modeling of DIII-D Disruption Events with the NIMROD Code
Linear ideal magnetohydrodynamic codes have long been used to predict the operating limits of tok... more Linear ideal magnetohydrodynamic codes have long been used to predict the operating limits of tokamak experiments. As accurate equilibrium reconstructions have become available, the ability to compare the spatial structure of the linear eigenfunctions with diagnostic measurements for ideal modes [1] and to compare with analytic predictions of the time behavior of the mode onset [2] has become possible for
Blob modeling in the scrape of layer of tokamak with the NIMROD code
Experimental observations and turbulence simulations of the far scrape off layer (SOL) suggest th... more Experimental observations and turbulence simulations of the far scrape off layer (SOL) suggest that the transport has non-diffusive nature and the density and particle fluxes are intermitted in this region of tokamak plasmas. Such observations can be explained by the strongly localized filaments of plasma pressure propagating in the radial direction. These filaments were observed in the experiments and are
The goal accomplished in thisproject was to improve the Synergia code by improving the integratio... more The goal accomplished in thisproject was to improve the Synergia code by improving the integration of the Impact space charge algorithms into Synergia and improving the graphical user interface for analyzing results. We accomplished five tasks along these lines: (i) a refactoring of the Impact space charge algorithm to make it more accessible by other codes, (ii) development of the
The Framework Architecture for Core-Edge Transport Simulations (FACETS) is a SciDAC project for s... more The Framework Architecture for Core-Edge Transport Simulations (FACETS) is a SciDAC project for self-consistent simulations of core-edge-wall transport in tokamaks using leadership class computers [1]. For analysis of transient peak power load handling, PFC erosion/deposition and lifetime, plasma impurity contamination, and hydrogen retention issues in FACETS, we developed the 1D continuum code WALLPSI [2]. WALLPSI simulates highly non-linear transport, release
There are several ongoing efforts to develop a software framework for integrated fusion simulatio... more There are several ongoing efforts to develop a software framework for integrated fusion simulations in the US (SWIM and CPES) the EU (ITM-TF) and Japan (BPSI). The European and Japanese efforts emphasize a standardization of the interfaces to codes within each subgroup (transport, equilibrium, linear stability, MHD, RF, turbulence, et cetera). The US efforts emphasize pairwise coupling of specific codes.
The NIMROD code[1] has been successfully validated against a number of standard linear and nonlin... more The NIMROD code[1] has been successfully validated against a number of standard linear and nonlinear test cases. During this validation campaign, resistive MHD calculations have generally been carried out at low to moderate values of the Lundquist number (10**3 < S 10**6). We have recently begun a systematic campaign to extend NIMROD calculations to higher values of S, and to determine the practical limits placed on this parameter. In this paper we report the initial results of this campaign based on previous calculations[2] carried out in simple linear cylindrical geometry. The realism of these calculations will be improved as the campaign prodeeds. While these initial results are based on the linearized MHD equations, we emphasize that the ultimate goal is to extend the values of S that can be used in fully nonlinear simulations. References: [1] A. H. Glasser, et al., Plasma Phys. Cont. Fus. 41, A747 (1999). [2] J. A. Holmes, et al., Phys. Fluids 26, 2569 (1083).
IEEE Transactions on Visualization and Computer Graphics, 2010
In the development of magnetic confinement fusion which will potentially be a future source for l... more In the development of magnetic confinement fusion which will potentially be a future source for low cost power, physicists must be able to analyze the magnetic field that confines the burning plasma. While the magnetic field can be described as a vector field, traditional techniques for analyzing the field's topology cannot be used because of its Hamiltonian nature. In this paper we describe a technique developed as a collaboration between physicists and computer scientists that determines the topology of a toroidal magnetic field using fieldlines with near minimal lengths. More specifically, we analyze the Poincaré map of the sampled fieldlines in a Poincaré section including identifying critical points and other topological features of interest to physicists. The technique has been deployed into an interactive parallel visualization tool which physicists are using to gain new insight into simulations of magnetically confined burning plasmas.
The Framework for Modernization and Componentization of Fusion Models (FMCFM) is an SBIR funded p... more The Framework for Modernization and Componentization of Fusion Models (FMCFM) is an SBIR funded project aimed at offering multiple, anomalous and neoclassical transport flux models within a single, multi-species and multi-language (Fortran, C/C++) friendly interface. ...
Motivated by the need to accurately predict the time evolution of profiles in tokamaks, we presen... more Motivated by the need to accurately predict the time evolution of profiles in tokamaks, we present initial results of core transport simulations using first principle anomalous and neoclassical flux calculations obtained from the GYRO and NEO codes, respectively. Sources are provided ...
Submitted for the APR12 Meeting of The American Physical Society Extended-MHD modeling of diamagn... more Submitted for the APR12 Meeting of The American Physical Society Extended-MHD modeling of diamagnetic-drift tearing instabilities 1 JACOB KING, SCOTT KRUGER, Tech-X Corporation-We use analytics and computations with the NIMROD code to examine tearing stability in large-guide-field slab cases with a nonzero equilibrium pressure gradient. A well known result from drift-reduced MHD is the diamagnetic drift associated with the pressure gradient has a stabilizing influence were the dispersion relation becomes (γ + iω * e) 3 γ(γ + iω * i) = γ 5 rM HD [1]. Here ω * i and ω * e are the ion-and electron-diamagnetic frequencies and γ rM HD is the tearing growth rate with a resistive-MHD model. Preliminary computational results with an unreduced extended-MHD model do not produce the expected drift-reduced result. For moderate values of ω * i (ω * i ≤ 3γ rM HD), the computations follow the dispersion relation that would result if the ∇p e term were not included in the drift-reduced parallel Ohm's law: (γ + iω * e) 4 (γ + iω * i) = γ 5 rM HD. Analytics, guided by computational diagnostics, are used to examine the significant terms in the flux evolution equation and investigate the discrepancy with the drift-reduced result.
In this talk, we highlight two analysis tools for evaluating fusion simulations. The first tool i... more In this talk, we highlight two analysis tools for evaluating fusion simulations. The first tool is for interactively exploring the topology of the magnetic field using a Poincaré map. Unlike traditional Poincaré maps that rely on a dense set of puncture points to form a contiguous representation of the magnetic surface we use a sparse set of connected puncture points. The puncture points are connected based on a rational approximation of the safety factor. The resulting analysis not only allows for the visualization of magnetic surfaces using a minimal number of puncture points but also identifies features such as magnetic islands. The second tool is for performing query based analysis on simulations utilizing particles. To assist in the analysis of simulation codes that utilize millions to billions of particles we have developed analysis tools that combine parallel coordinates plots combine with accelerated index searches. Parallel coordinate plots allow one to identify trends with...
MHD Modeling of DIII-D Disruption Events with the NIMROD Code
Linear ideal magnetohydrodynamic codes have long been used to predict the operating limits of tok... more Linear ideal magnetohydrodynamic codes have long been used to predict the operating limits of tokamak experiments. As accurate equilibrium reconstructions have become available, the ability to compare the spatial structure of the linear eigenfunctions with diagnostic measurements for ideal modes [1] and to compare with analytic predictions of the time behavior of the mode onset [2] has become possible for
Blob modeling in the scrape of layer of tokamak with the NIMROD code
Experimental observations and turbulence simulations of the far scrape off layer (SOL) suggest th... more Experimental observations and turbulence simulations of the far scrape off layer (SOL) suggest that the transport has non-diffusive nature and the density and particle fluxes are intermitted in this region of tokamak plasmas. Such observations can be explained by the strongly localized filaments of plasma pressure propagating in the radial direction. These filaments were observed in the experiments and are
The goal accomplished in thisproject was to improve the Synergia code by improving the integratio... more The goal accomplished in thisproject was to improve the Synergia code by improving the integration of the Impact space charge algorithms into Synergia and improving the graphical user interface for analyzing results. We accomplished five tasks along these lines: (i) a refactoring of the Impact space charge algorithm to make it more accessible by other codes, (ii) development of the
The Framework Architecture for Core-Edge Transport Simulations (FACETS) is a SciDAC project for s... more The Framework Architecture for Core-Edge Transport Simulations (FACETS) is a SciDAC project for self-consistent simulations of core-edge-wall transport in tokamaks using leadership class computers [1]. For analysis of transient peak power load handling, PFC erosion/deposition and lifetime, plasma impurity contamination, and hydrogen retention issues in FACETS, we developed the 1D continuum code WALLPSI [2]. WALLPSI simulates highly non-linear transport, release
There are several ongoing efforts to develop a software framework for integrated fusion simulatio... more There are several ongoing efforts to develop a software framework for integrated fusion simulations in the US (SWIM and CPES) the EU (ITM-TF) and Japan (BPSI). The European and Japanese efforts emphasize a standardization of the interfaces to codes within each subgroup (transport, equilibrium, linear stability, MHD, RF, turbulence, et cetera). The US efforts emphasize pairwise coupling of specific codes.
The NIMROD code[1] has been successfully validated against a number of standard linear and nonlin... more The NIMROD code[1] has been successfully validated against a number of standard linear and nonlinear test cases. During this validation campaign, resistive MHD calculations have generally been carried out at low to moderate values of the Lundquist number (10**3 < S 10**6). We have recently begun a systematic campaign to extend NIMROD calculations to higher values of S, and to determine the practical limits placed on this parameter. In this paper we report the initial results of this campaign based on previous calculations[2] carried out in simple linear cylindrical geometry. The realism of these calculations will be improved as the campaign prodeeds. While these initial results are based on the linearized MHD equations, we emphasize that the ultimate goal is to extend the values of S that can be used in fully nonlinear simulations. References: [1] A. H. Glasser, et al., Plasma Phys. Cont. Fus. 41, A747 (1999). [2] J. A. Holmes, et al., Phys. Fluids 26, 2569 (1083).
IEEE Transactions on Visualization and Computer Graphics, 2010
In the development of magnetic confinement fusion which will potentially be a future source for l... more In the development of magnetic confinement fusion which will potentially be a future source for low cost power, physicists must be able to analyze the magnetic field that confines the burning plasma. While the magnetic field can be described as a vector field, traditional techniques for analyzing the field's topology cannot be used because of its Hamiltonian nature. In this paper we describe a technique developed as a collaboration between physicists and computer scientists that determines the topology of a toroidal magnetic field using fieldlines with near minimal lengths. More specifically, we analyze the Poincaré map of the sampled fieldlines in a Poincaré section including identifying critical points and other topological features of interest to physicists. The technique has been deployed into an interactive parallel visualization tool which physicists are using to gain new insight into simulations of magnetically confined burning plasmas.
The Framework for Modernization and Componentization of Fusion Models (FMCFM) is an SBIR funded p... more The Framework for Modernization and Componentization of Fusion Models (FMCFM) is an SBIR funded project aimed at offering multiple, anomalous and neoclassical transport flux models within a single, multi-species and multi-language (Fortran, C/C++) friendly interface. ...
Motivated by the need to accurately predict the time evolution of profiles in tokamaks, we presen... more Motivated by the need to accurately predict the time evolution of profiles in tokamaks, we present initial results of core transport simulations using first principle anomalous and neoclassical flux calculations obtained from the GYRO and NEO codes, respectively. Sources are provided ...
Submitted for the APR12 Meeting of The American Physical Society Extended-MHD modeling of diamagn... more Submitted for the APR12 Meeting of The American Physical Society Extended-MHD modeling of diamagnetic-drift tearing instabilities 1 JACOB KING, SCOTT KRUGER, Tech-X Corporation-We use analytics and computations with the NIMROD code to examine tearing stability in large-guide-field slab cases with a nonzero equilibrium pressure gradient. A well known result from drift-reduced MHD is the diamagnetic drift associated with the pressure gradient has a stabilizing influence were the dispersion relation becomes (γ + iω * e) 3 γ(γ + iω * i) = γ 5 rM HD [1]. Here ω * i and ω * e are the ion-and electron-diamagnetic frequencies and γ rM HD is the tearing growth rate with a resistive-MHD model. Preliminary computational results with an unreduced extended-MHD model do not produce the expected drift-reduced result. For moderate values of ω * i (ω * i ≤ 3γ rM HD), the computations follow the dispersion relation that would result if the ∇p e term were not included in the drift-reduced parallel Ohm's law: (γ + iω * e) 4 (γ + iω * i) = γ 5 rM HD. Analytics, guided by computational diagnostics, are used to examine the significant terms in the flux evolution equation and investigate the discrepancy with the drift-reduced result.
Uploads
Papers by Scott Kruger