# Nonlinear gyrofluid models of shear Alfven instabilities in ignited and beam heated toroidal plasmas

## Abstract

Shear Alfven instabilities driven by energetic beams and alpha populations are investigated using a reduced MHD-gyrofluid model with Landau closure. The moment equations for the fast ions are truncated in a way which incorporates the wave particle resonances that are required to destabilize the shear Alfven mode. These are coupled to an Ohm`s law and vorticity equations which have been generalized to include ion FLR, electron and ion Landau damping. This model has been applied to experimentally observed regimes in a number of tokamak and stellarator devices. Both linearized growth rates and the nonlinear evolution are obtained. The saturated nonlinear regimes indicate mode number and frequency spectra which are generally consistent with experiment. A detailed examination of one typical nonlinear state has allowed identification of the dominant saturation mechanisms. This indicates that generation of n = 0, m = 0 sheared poloidal velocity flows and quasi linear modification of the q(r) profile can be important factors in reaching saturation.

- Authors:

- Publication Date:

- Research Org.:
- Oak Ridge National Lab., TN (United States)

- Sponsoring Org.:
- USDOE, Washington, DC (United States)

- OSTI Identifier:
- 10168952

- Report Number(s):
- CONF-9305231-1

ON: DE93016235; TRN: 93:016296

- DOE Contract Number:
- AC05-84OR21400

- Resource Type:
- Conference

- Resource Relation:
- Conference: International Atomic Energy Agency (IAEA) technical committee meeting,Trieste (Italy),10-14 May 1993; Other Information: PBD: [1993]

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA INSTABILITY; ALFVEN WAVES; INSTABILITY GROWTH RATES; CLOSED PLASMA DEVICES; NEUTRAL ATOM BEAM INJECTION; THERMONUCLEAR IGNITION; SHEAR; LANDAU DAMPING; MAGNETOHYDRODYNAMICS; TOKAMAK DEVICES; ALPHA PARTICLES; STELLARATORS; NONLINEAR PROBLEMS; 700340; PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES

### Citation Formats

```
Spong, D A, Hedrick, C L, and Carreras, B A.
```*Nonlinear gyrofluid models of shear Alfven instabilities in ignited and beam heated toroidal plasmas*. United States: N. p., 1993.
Web.

```
Spong, D A, Hedrick, C L, & Carreras, B A.
```*Nonlinear gyrofluid models of shear Alfven instabilities in ignited and beam heated toroidal plasmas*. United States.

```
Spong, D A, Hedrick, C L, and Carreras, B A. 1993.
"Nonlinear gyrofluid models of shear Alfven instabilities in ignited and beam heated toroidal plasmas". United States. https://www.osti.gov/servlets/purl/10168952.
```

```
@article{osti_10168952,
```

title = {Nonlinear gyrofluid models of shear Alfven instabilities in ignited and beam heated toroidal plasmas},

author = {Spong, D A and Hedrick, C L and Carreras, B A},

abstractNote = {Shear Alfven instabilities driven by energetic beams and alpha populations are investigated using a reduced MHD-gyrofluid model with Landau closure. The moment equations for the fast ions are truncated in a way which incorporates the wave particle resonances that are required to destabilize the shear Alfven mode. These are coupled to an Ohm`s law and vorticity equations which have been generalized to include ion FLR, electron and ion Landau damping. This model has been applied to experimentally observed regimes in a number of tokamak and stellarator devices. Both linearized growth rates and the nonlinear evolution are obtained. The saturated nonlinear regimes indicate mode number and frequency spectra which are generally consistent with experiment. A detailed examination of one typical nonlinear state has allowed identification of the dominant saturation mechanisms. This indicates that generation of n = 0, m = 0 sheared poloidal velocity flows and quasi linear modification of the q(r) profile can be important factors in reaching saturation.},

doi = {},

url = {https://www.osti.gov/biblio/10168952},
journal = {},

number = ,

volume = ,

place = {United States},

year = {1993},

month = {7}

}