# Resonant-magnetic-perturbation-induced plasma transport in H-mode pedestals

## Abstract

Plasma toroidal rotation reduces reconnection of externally applied resonant magnetic perturbation (RMP) fields {delta}B on rational (q = m/n) magnetic flux surfaces. Hence, it causes radial perturbations {delta}B{sub {rho}m/n} to be small there, and thus inhibits magnetic island formation and stochasticity in the edge of high (H-) mode confinement tokamak plasmas. However, electron collisional damping combined with the spatial magnetic flutter {delta}B{sub {rho}m/n} induced by RMPs in the vicinity of rational surfaces causes a radial electron heat diffusivity in which {chi}{sub e Parallel-To }{sup eff}{approx}(v{sub Te}{sup 2}/{nu}{sub e})/(1+x{sup 2}/{delta}{sub Parallel-To }{sup 2}) is an effective parallel electron thermal diffusivity. These effects are reduced by magnetic shear effects at a distance x from rational surfaces for |x|>{delta}{sub Parallel-To} but amplified for {delta}B-caret{sub {rho}m/n}(x)>{delta}B-caret{sub {rho}m/n}(0). A kinetic, toroidal model of these RMP-flutter-induced plasma transport effects is developed and compared to a previously developed cylindrical model. The RMP-induced increases in plasma transport can be large enough to reduce plasma gradients in H-mode pedestals. Thus, they may contribute to suppressing edge localized modes in tokamak plasmas.

- Authors:

- University of Wisconsin, 1500 Engineering Drive, Madison, Wisconsin 53706-1609 (United States)
- Columbia University, 201 S.W. Mudd, New York, New York 10027 (United States)

- Publication Date:

- OSTI Identifier:
- 22068893

- Resource Type:
- Journal Article

- Journal Name:
- Physics of Plasmas

- Additional Journal Information:
- Journal Volume: 19; Journal Issue: 11; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CYLINDRICAL CONFIGURATION; DISTURBANCES; EDGE LOCALIZED MODES; ELECTRON COLLISIONS; H-MODE PLASMA CONFINEMENT; MAGNETIC FLUX; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; MODE RATIONAL SURFACES; PLASMA; THERMAL DIFFUSIVITY; TOKAMAK DEVICES; TOROIDAL CONFIGURATION

### Citation Formats

```
Callen, J. D., Hegna, C. C., and Cole, A. J.
```*Resonant-magnetic-perturbation-induced plasma transport in H-mode pedestals*. United States: N. p., 2012.
Web. doi:10.1063/1.4767642.

```
Callen, J. D., Hegna, C. C., & Cole, A. J.
```*Resonant-magnetic-perturbation-induced plasma transport in H-mode pedestals*. United States. doi:10.1063/1.4767642.

```
Callen, J. D., Hegna, C. C., and Cole, A. J. Thu .
"Resonant-magnetic-perturbation-induced plasma transport in H-mode pedestals". United States. doi:10.1063/1.4767642.
```

```
@article{osti_22068893,
```

title = {Resonant-magnetic-perturbation-induced plasma transport in H-mode pedestals},

author = {Callen, J. D. and Hegna, C. C. and Cole, A. J.},

abstractNote = {Plasma toroidal rotation reduces reconnection of externally applied resonant magnetic perturbation (RMP) fields {delta}B on rational (q = m/n) magnetic flux surfaces. Hence, it causes radial perturbations {delta}B{sub {rho}m/n} to be small there, and thus inhibits magnetic island formation and stochasticity in the edge of high (H-) mode confinement tokamak plasmas. However, electron collisional damping combined with the spatial magnetic flutter {delta}B{sub {rho}m/n} induced by RMPs in the vicinity of rational surfaces causes a radial electron heat diffusivity in which {chi}{sub e Parallel-To }{sup eff}{approx}(v{sub Te}{sup 2}/{nu}{sub e})/(1+x{sup 2}/{delta}{sub Parallel-To }{sup 2}) is an effective parallel electron thermal diffusivity. These effects are reduced by magnetic shear effects at a distance x from rational surfaces for |x|>{delta}{sub Parallel-To} but amplified for {delta}B-caret{sub {rho}m/n}(x)>{delta}B-caret{sub {rho}m/n}(0). A kinetic, toroidal model of these RMP-flutter-induced plasma transport effects is developed and compared to a previously developed cylindrical model. The RMP-induced increases in plasma transport can be large enough to reduce plasma gradients in H-mode pedestals. Thus, they may contribute to suppressing edge localized modes in tokamak plasmas.},

doi = {10.1063/1.4767642},

journal = {Physics of Plasmas},

issn = {1070-664X},

number = 11,

volume = 19,

place = {United States},

year = {2012},

month = {11}

}