# Effects of Asymmetries in Computations of Forced Vertical Displacement Events

## Abstract

Visco-resistive MHD computations with the NIMROD code [J. Comput. Phys. 195 355 (2004)] are applied to a model tokamak configuration that is subjected to induced vertical displacement. The modeling includes anisotropic thermal conduction within an evolving magnetic topology, and parameters separate the Alfvénic, resistive-wall, and plasma-resistive timescales. Contact with the wall leads to increasingly pervasive kink and tearing dynamics. The computed 3D evolution reproduces distinct thermal-quench and current-quench timescales, a positive bump in plasma current, and net horizontal forcing on the resistive wall. The MHD dynamo effect electric field, E_f=-, is analyzed for understanding the nonlinear effects of the fluctuations on the spreading of parallel current density and the resulting bump in plasma current. Forces on the resistive wall are consistent with Pustovitov's analysis [Nucl. Fusion 55 113032 (2015)]; the plasma remains in approximate force-balance with the wall, so net force is accurately computed from integrating stress over the wall's outer surface. Improvements to the modeling that are needed for predictive simulation of asymmetric vertical displacement events are discussed.

- Authors:

- Publication Date:

- Research Org.:
- Univ. of Wisconsin‐Madison, Madison, WI (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)

- OSTI Identifier:
- 1482395

- Alternate Identifier(s):
- OSTI ID: 1482375; OSTI ID: 1482394

- Grant/Contract Number:
- SC0018001

- Resource Type:
- Journal Article: Accepted Manuscript

- Journal Name:
- Plasma Physics and Controlled Fusion

- Additional Journal Information:
- Journal Name: Plasma Physics and Controlled Fusion; Journal ID: ISSN 0741-3335

- Publisher:
- IOP Science

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamak disruption; vertical displacement event; mhd computation; tokamak disruption, vertical displacement event, MHD computation

### Citation Formats

```
Sovinec, Carl R., and Bunkers, Kyle.
```*Effects of Asymmetries in Computations of Forced Vertical Displacement Events*. United States: N. p., 2018.
Web. doi:10.1088/1361-6587/aaf124.

```
Sovinec, Carl R., & Bunkers, Kyle.
```*Effects of Asymmetries in Computations of Forced Vertical Displacement Events*. United States. doi:10.1088/1361-6587/aaf124.

```
Sovinec, Carl R., and Bunkers, Kyle. Thu .
"Effects of Asymmetries in Computations of Forced Vertical Displacement Events". United States.
doi:10.1088/1361-6587/aaf124. https://www.osti.gov/servlets/purl/1482395.
```

```
@article{osti_1482395,
```

title = {Effects of Asymmetries in Computations of Forced Vertical Displacement Events},

author = {Sovinec, Carl R. and Bunkers, Kyle},

abstractNote = {Visco-resistive MHD computations with the NIMROD code [J. Comput. Phys. 195 355 (2004)] are applied to a model tokamak configuration that is subjected to induced vertical displacement. The modeling includes anisotropic thermal conduction within an evolving magnetic topology, and parameters separate the Alfvénic, resistive-wall, and plasma-resistive timescales. Contact with the wall leads to increasingly pervasive kink and tearing dynamics. The computed 3D evolution reproduces distinct thermal-quench and current-quench timescales, a positive bump in plasma current, and net horizontal forcing on the resistive wall. The MHD dynamo effect electric field, E_f=-, is analyzed for understanding the nonlinear effects of the fluctuations on the spreading of parallel current density and the resulting bump in plasma current. Forces on the resistive wall are consistent with Pustovitov's analysis [Nucl. Fusion 55 113032 (2015)]; the plasma remains in approximate force-balance with the wall, so net force is accurately computed from integrating stress over the wall's outer surface. Improvements to the modeling that are needed for predictive simulation of asymmetric vertical displacement events are discussed.},

doi = {10.1088/1361-6587/aaf124},

journal = {Plasma Physics and Controlled Fusion},

number = ,

volume = ,

place = {United States},

year = {Thu Nov 15 00:00:00 EST 2018},

month = {Thu Nov 15 00:00:00 EST 2018}

}