# COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES

## Abstract

OAK-B135 The gyrokinetic equations predict that various drift type waves or modes can be unstable in a tokamak. For some of these modes, such as the ion temperature gradient (ITG) mode and the electron temperature gradient mode, there exists a critical gradient, above which the mode is unstable. Since the existence of unstable modes can cause increased transport, plasmas which are centrally heated tend to increase in temperature gradient until the modes become unstable. Under some conditions the increased transport can fix the gradient at the critical value. here they present a comparison between the measured ion temperature gradients and the critical gradient as calculated by a gyrokinetic linear stability (GKS) code. They also present the maximum linear growth rate as calculated by this code for comparison to experimentally derived transport coefficients. The results show that for low confinement mode (L-mode) discharges, the measured ion temperature gradient is significantly greater than the GKS calculated critical gradient over a large region of the plasma. This is the same region of the plasma where the ion thermal diffusivity is large. For high confinement mode (H-mode) discharges the ion temperature gradient is closer to the critical gradient, but often still greater than themore »

- Authors:

- Publication Date:

- Research Org.:
- GENERAL ATOMICS (US)

- Sponsoring Org.:
- (US)

- OSTI Identifier:
- 821789

- DOE Contract Number:
- AC03-99ER54463

- Resource Type:
- Journal Article

- Journal Name:
- PHYS. PLASMAS.

- Additional Journal Information:
- Other Information: Submitted to PHYS. PLASMAS.; PBD: 1 Apr 2003

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CONFINEMENT; DOUBLET-3 DEVICE; ELECTRON TEMPERATURE; ION TEMPERATURE; PLASMA; STABILITY; TEMPERATURE GRADIENTS; THERMAL DIFFUSIVITY; TRANSPORT

### Citation Formats

```
BAKER,DR, STAEBLER,GM, PETTY,CC, GREENFIELD,CM, and LUCE,TC.
```*COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES*. United States: N. p., 2003.
Web. doi:10.1063/1.1621001.

```
BAKER,DR, STAEBLER,GM, PETTY,CC, GREENFIELD,CM, & LUCE,TC.
```*COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES*. United States. doi:10.1063/1.1621001.

```
BAKER,DR, STAEBLER,GM, PETTY,CC, GREENFIELD,CM, and LUCE,TC. Tue .
"COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES". United States. doi:10.1063/1.1621001. https://www.osti.gov/servlets/purl/821789.
```

```
@article{osti_821789,
```

title = {COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES},

author = {BAKER,DR and STAEBLER,GM and PETTY,CC and GREENFIELD,CM and LUCE,TC},

abstractNote = {OAK-B135 The gyrokinetic equations predict that various drift type waves or modes can be unstable in a tokamak. For some of these modes, such as the ion temperature gradient (ITG) mode and the electron temperature gradient mode, there exists a critical gradient, above which the mode is unstable. Since the existence of unstable modes can cause increased transport, plasmas which are centrally heated tend to increase in temperature gradient until the modes become unstable. Under some conditions the increased transport can fix the gradient at the critical value. here they present a comparison between the measured ion temperature gradients and the critical gradient as calculated by a gyrokinetic linear stability (GKS) code. They also present the maximum linear growth rate as calculated by this code for comparison to experimentally derived transport coefficients. The results show that for low confinement mode (L-mode) discharges, the measured ion temperature gradient is significantly greater than the GKS calculated critical gradient over a large region of the plasma. This is the same region of the plasma where the ion thermal diffusivity is large. For high confinement mode (H-mode) discharges the ion temperature gradient is closer to the critical gradient, but often still greater than the critical gradient over some region. For the best H-mode discharges, the ion temperature is less than or equal to the critical gradient over the whole plasma. In general they find that the position in the plasma where the ion thermal diffusivity starts to increase rapidly is where the maximum linear growth rate is greater than the E x B shearing rate.},

doi = {10.1063/1.1621001},

journal = {PHYS. PLASMAS.},

number = ,

volume = ,

place = {United States},

year = {2003},

month = {4}

}