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# Gyrokinetic simulations of m=0 mode in sheared flow Z-pinch

## Abstract

Axisymmetric stability properties of sheared flow Z-pinch plasmas are studied by making use of the gyrokinetic approximation in the long-wavelength limit. Numerical simulations are carried out with the high-order finite-volume code COntinuum Gyrokinetic Edge New Technology (COGENT) and are analyzed for the parameters characteristic of the FuZE experiment. Reduction of the linear growth rate with increasing shear is observed, and the results are elucidated by making use of a local dispersion relation analysis. In addition, COGENT simulations are compared with fully kinetic particle-in-cell simulations, and with an ideal magnetohydrodynamics (MHD) model. Good agreement between the gyrokinetic and fully kinetic results for the linear stability is found, with the gyrokinetic model requiring much less computational time due to its ability to step over particle gyroperiod. The ideal MHD model is found to be consistent with the kinetic models in the long-wavelength part of the spectra ($$kρ_i$$), while failing to adequately predict short-scale ($$kρ_i$$) stability. Here, $k$ is the axial wavelength vector and $$ρ_i$$ is the ion gyroradius.

- Authors:

- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

- Publication Date:

- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)

- OSTI Identifier:
- 1560115

- Alternate Identifier(s):
- OSTI ID: 1526656

- Report Number(s):
- LLNL-JRNL-769250

Journal ID: ISSN 1070-664X; 960511

- Grant/Contract Number:
- AC52-07NA27344

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physics of Plasmas

- Additional Journal Information:
- Journal Volume: vol. 26; Journal Issue: no. 6; Journal ID: ISSN 1070-664X

- Publisher:
- American Institute of Physics (AIP)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

### Citation Formats

```
Geyko, V. I., Dorf, M., and Angus, J. R. Gyrokinetic simulations of m=0 mode in sheared flow Z-pinch. United States: N. p., 2019.
Web. doi:10.1063/1.5100542.
```

```
Geyko, V. I., Dorf, M., & Angus, J. R. Gyrokinetic simulations of m=0 mode in sheared flow Z-pinch. United States. doi:10.1063/1.5100542.
```

```
Geyko, V. I., Dorf, M., and Angus, J. R. Mon .
"Gyrokinetic simulations of m=0 mode in sheared flow Z-pinch". United States. doi:10.1063/1.5100542.
```

```
@article{osti_1560115,
```

title = {Gyrokinetic simulations of m=0 mode in sheared flow Z-pinch},

author = {Geyko, V. I. and Dorf, M. and Angus, J. R.},

abstractNote = {Axisymmetric stability properties of sheared flow Z-pinch plasmas are studied by making use of the gyrokinetic approximation in the long-wavelength limit. Numerical simulations are carried out with the high-order finite-volume code COntinuum Gyrokinetic Edge New Technology (COGENT) and are analyzed for the parameters characteristic of the FuZE experiment. Reduction of the linear growth rate with increasing shear is observed, and the results are elucidated by making use of a local dispersion relation analysis. In addition, COGENT simulations are compared with fully kinetic particle-in-cell simulations, and with an ideal magnetohydrodynamics (MHD) model. Good agreement between the gyrokinetic and fully kinetic results for the linear stability is found, with the gyrokinetic model requiring much less computational time due to its ability to step over particle gyroperiod. The ideal MHD model is found to be consistent with the kinetic models in the long-wavelength part of the spectra ($kρ_i$), while failing to adequately predict short-scale ($kρ_i$) stability. Here, $k$ is the axial wavelength vector and $ρ_i$ is the ion gyroradius.},

doi = {10.1063/1.5100542},

journal = {Physics of Plasmas},

number = no. 6,

volume = vol. 26,

place = {United States},

year = {2019},

month = {6}

}

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