### Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence

Here, this article presents a calculation of the mean electromotive force arising from general small-scale magnetohydrodynamical turbulence, within the framework of the second-order correlation approximation. With the goal of improving understanding of the accretion disk dynamo, effects arising through small-scale magnetic fluctuations, velocity gradients, density and turbulence stratification, and rotation, are included. The primary result, which supplements numerical findings, is that an off-diagonal turbulent resistivity due to

*magnetic fluctuations*can produce large-scale dynamo action-the magnetic analog of the "shear-current" effect. In addition, consideration of alpha effects in the stratified regions of disks gives the puzzling result that there is no strong prediction for a sign of alpha, since the effects due to kinetic and magnetic fluctuations, as well as those due to shear and rotation, are each of opposing signs and tend to cancel each other.- Publication Date:

- Report Number(s):
- PPPL-5183

Journal ID: ISSN 1539-3755; PLEEE8

- Grant/Contract Number:
- AC02-09CH11466; AC02-09-CH11466

- Type:
- Accepted Manuscript

- Journal Name:
- Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print)

- Additional Journal Information:
- Journal Name: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print); Journal Volume: 92; Journal Issue: 5; Journal ID: ISSN 1539-3755

- Publisher:
- American Physical Society (APS)

- Research Org:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

- Sponsoring Org:
- USDOE

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

- OSTI Identifier:
- 1256591

- Alternate Identifier(s):
- OSTI ID: 1224869

```
Squire, J., and Bhattacharjee, A..
```*Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence*. United States: N. p.,
Web. doi:10.1103/PhysRevE.92.053101.

```
Squire, J., & Bhattacharjee, A..
```*Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence*. United States. doi:10.1103/PhysRevE.92.053101.

```
Squire, J., and Bhattacharjee, A.. 2015.
"Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence". United States.
doi:10.1103/PhysRevE.92.053101. https://www.osti.gov/servlets/purl/1256591.
```

```
@article{osti_1256591,
```

title = {Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence},

author = {Squire, J. and Bhattacharjee, A.},

abstractNote = {Here, this article presents a calculation of the mean electromotive force arising from general small-scale magnetohydrodynamical turbulence, within the framework of the second-order correlation approximation. With the goal of improving understanding of the accretion disk dynamo, effects arising through small-scale magnetic fluctuations, velocity gradients, density and turbulence stratification, and rotation, are included. The primary result, which supplements numerical findings, is that an off-diagonal turbulent resistivity due to magnetic fluctuations can produce large-scale dynamo action-the magnetic analog of the "shear-current" effect. In addition, consideration of alpha effects in the stratified regions of disks gives the puzzling result that there is no strong prediction for a sign of alpha, since the effects due to kinetic and magnetic fluctuations, as well as those due to shear and rotation, are each of opposing signs and tend to cancel each other.},

doi = {10.1103/PhysRevE.92.053101},

journal = {Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print)},

number = 5,

volume = 92,

place = {United States},

year = {2015},

month = {11}

}