Publications by Ralf Gruber | EPFL Graph Search

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The three-dimensional (3-D) VMEC code has been modified to model an energetic species with a variant of a Bi-Maxwellian distribution function that satisfies the constraint B . del F-h = 0, and the 3-D TERPSICHORE stability code has been extended to investi ...

Equations for the three-dimensional equilibrium of a plasma are formulated in the poloidal representation. The magnetic field is expressed in terms of the poloidal magnetic flux Psi and the poloidal electric current F. As a result, three-dimensional equilibrium configurations are analyzed with the help of a set of equations including the elliptical equation for the poloidal flux, the magnetic differential equation for the parallel current, and the equations for the basis vector field b. To overcome the diff

The paper presents the KINX code for computing linear ideal MHD growth rates and eigenvectors of axisymmetric plasmas surrounded by a vacuum layer and a conducting wall. Plasma equilibrium magnetic surfaces are assumed to be nested either in the whole plasma domain (separatrix at the plasma boundary is possible) or in the domains separated by an internal separatrix (doublet and divertor configurations). The computational domain is decomposed into subdomains with nested flux surfaces. In each subdomain finit

As pragmatic users of high performance supercomputers, we believe that nowadays parallel computer architectures with distributed memories are not vet mature to be used by a wide range of application engineers. A big effort should be made to bring these very promising computers closer to the users. One major flaw of massively parallel machines is that the programmer has to take care himself of the data flow which is often different on different parallel computers. To overcome this problem, we propose that da

A program environment is presented that enables a co-operative design of high-technology products demanding interdisciplinary computer simulations for their optimisation. The system includes a multi-site, multi-machine, distributed data manager accessible by a data monitor. A client-server concept supports the user of massively parallel machines. The exchange of data between different executable scientific application modules is performed through the data base. Special modules to define the geometry, to dec

An energy functional given by W = integral integral integral d3x[B2/(2mu0) + p(parallel-to)/(GAMMA - 1)] is proposed as a variational principle to determine three-dimensional (3D) magnetohydrodynamic (MHD) equilibria with anisotropic plasma pressure. It is demonstrated that the minimisation of W using an inverse coordinate spectral method reproduces the force balance relations that govern the MHD equilibrium properties of 3D plasmas with p(parallel-to) not-equal p(parpendicular-to) that have nested magnetic

We describe a few relevant aspects of the new plasma physics stability code, TERPSICHORE, which breaks new ground both in plasma theory and in its algorithmic implementation. We chose a highly accurate discrete mathematical representation which led to the choice of algorithms that matched the vector-parallel architecture of the Cray Y-MP and Cray-2 supercomputers quite well. The resulting code runs at Gflop/s speeds, which translates into a very high efficiency. This means we can perform very extensive stud

The TERPSICHORE three-dimensional linear ideal magnetohydrodynamic (MHD) stability code [Theory of Fusion Plasmas, Proceedings of the Joint Varenna-Lausanne International Workshop, Chexbres, Switzerland, 1988 (Editrice Compositori, Bologna, Italy, 1989), p. 93; Controlled Fusion and Plasma Heating, Proceedings of the 17th European Conference, Amsterdam, The Netherlands (European Physical Society, Petit-Lancy, Switzerland, 1990), Vol. 14B, Part II, p. 931; Theory of Fusion Plasmas, Proceedings of the Joint V

The direct sparse matrix solver is based on a domain decomposition technique to achieve data and work parallelization. Geometries that have long and thin structures are specially efficiently tractable with this solver, provided that they can be decomposed mainly in one direction. Due to the separation of the algorithm into a factorization stage and a solution stage, time-dependent problems with a constant coefficient matrix are particularly well suited for this solver. The parallelization performances obtai

We present the application of the recent physics-conforming COOL method [2,4] to the eigenvalue problem of a cylindrical waveguide filled with unmagnetized plasma. Using the Fourier transform only along the waveguide and not in poloidal direction, this is ...

An incompressible variational ideal ballooning mode equation is discretized with the COOL finite element discretization scheme using basis functions composed of variable order Legendre polynomials. This reduces the second order ordinary differential equati ...

Ralf Gruber

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Stability properties of anisotropic pressure stellarator plasmas with fluid and noninteractive energetic particles

Three-dimensional plasma equilibrium model based on the poloidal representation of the magnetic field

The KINX ideal MHD stability code for axisymmetric plasmas with separatrix

Software-Development Strategies for Parallel Computer Architectures

Problem-solving environment for parallel computers

3d Magnetohydrodynamic Equilibria with Anisotropic Pressure

The Terpsichore Code for the Stability Analysis of Magnetically Confined Fusion Plasmas

Fully 3-Dimensional Ideal Magnetohydrodynamic Stability Analysis of Low-N Modes and Mercier Modes in Stellarators

A direct parallel sparse matrix solver

Modes of a plasma-filled waveguide determined by a numerical hp method

BECOOL: Ballooning eigensolver with COOL finite elements

New Finite-Element Approach to Normal Mode Analysis in Magnetohydrodynamics

b limits in H-mode like discharges

Finite-Element Methods to Calculate Ideal Magnetohydrodynamic Flow Equilibria in Tokamaks

Mhd Spectrum of Reversed Field Pinch Configurations

Alfvén wave heating in toroidal plasmas

Numerical computation of the MHD spectrum of non-circular, small aspect ratio tokamaks

Axisymmetric toroidal equilibrium with flow and anisotropic pressure

Study of reversed field pinch with surface current

Beta limit in racetrack-shaped tokamaks