# Presentation: 211965

## Numerical Computation of Wave-Plasma Interactions in Multi-dimensional Systems

- D.B. Batchelor, L.A. Berry, M.D. Carter,
- E.F. Jaeger,  E. D’Azevedo, L. Gray, T. Kaplan

- P.T. Bonoli
- J.C. Wright

- C.K. Phillips, R. Dumont

- D.N. Smithe

**Lodestar Research Corporation**
- D.A. D’Ippolito, J. Myra

- Visit our web site at http://www.ornl.gov/fed/scidacrf

- R.W. Harvey

## Goal

**Obtain quantitatively accurate, predictive understanding of electromagnetic wave processes that support important heating, current drive, and stability and transport applications in fusion-relevant plasmas**

**TeraScale Supercomputers are providing ****access to new plasma wave physics**

**In non-uniform plasma****modes can couple**

## Massively - Parallel Computers Provide Access to New Plasma Wave Physics

**Higher dimensionality - Computation of important wave features in 2-D and 3-D**
**Higher resolution - Power to resolve short wavelength structures arising from mode conversion, high dielectric constant or multi-wave interference effects**
**Improved calculation of wave driven plasma currents resulting from the ability to represent arbitrary, non-maxwellian distributions; retain high cyclotron harmonics; include non-local and non-linear effects in the conductivity operator**
**Inclusion of the effects of non-thermal populations on wave propagation and absorption**

## Increasing Resolution Results in Proper Radial Localization of Mode Converted  Wavefields

**N****m****= 15**

**N****m****= 511**

## Project Overview

**Obtain predictive understanding of electromagnetic wave processes in fusion relevant plasmas with emphasis on four major physics areas:**
**Effect of plasma inhomogeneity in 2-D and 3-D on wave absorption and mode conversion processes.**
**Effect of non-Maxwellian (generalized) velocity space particle distributions on local wave absorption, momentum generation, and instabilities.**
**Application of full-wave solvers to ultra-short wavelength regimes (e.g. lower hybrid waves).**
**Effect of global plasma modes on wave fields produced by launching structures (antennas).**

## Computational and Mathematical Challenges

- High dimensionality – p.d.e. in 2D or 3D for wave fields, up to 5D for distribution function
-       Large numbers of unknowns 105  >106
- Complex medium
- Spatially non-uniform
- Anisotropic
- Non-local – local plasma current is an integral operator over EM field at other locations at earlier times
-     Use of spectral representations
- Wide range of length scales involved  – ~ L  << Llength scales can interact in localized plasma regions    mode conversion
-     Need for adaptive (but spectral) representation
- Variety of physics mechanisms for absorption
- Non-linearity – waves modify plasma on slow time scale, non-linear effects on waves
- Basic equations are non-symmetric and dissipative

**QPS Compact Stellarator**

## Collaborative Research Supported by DOEOffice of Fusion Energy Science and Office of Advanced Scientific Computing Research are Resulting in the Achievement of Physics Goals

**Implementation of 1-D, 2-D, and 3-D full-wave and Fokker Planck solvers on massively parallel platforms.**
**Adaptation of improved serial and parallel algorithms for evaluating macroscopic plasma responses.**
**Reformulating wave-plasma problems and solution methods.**

## High Resolution (Nm = 160  511) is Necessary in this Mode Conversion Problem to Get The Physics Right Algorithm enhancements and MPP allowed 103 larger problem to be solved (Nm=15511)