# Helicity content and tokamak applications of helicity

## Abstract

Magnetic helicity is approximately conserved by the turbulence associated with resistive instabilities of plasmas. To generalize the application of the concept of helicity, the helicity content of an arbitrary bounded region of space will be defined. The definition has the virtues that both the helicity content and its time derivative have simple expressions in terms of the poloidal and toroidal magnetic fluxes, the average toroidal loop voltage and the electric potential on the bounding surface, and the volume integral of E-B. The application of the helicity concept to tokamak plasmas is illustrated by a discussion of so-called MHD current drive, an example of a stable tokamak q profile with q less than one in the center, and a discussion of the possibility of a natural steady-state tokamak due to the bootstrap current coupling to tearing instabilities.

- Authors:

- Publication Date:

- Research Org.:
- Princeton Univ., NJ (USA). Plasma Physics Lab.

- OSTI Identifier:
- 5628601

- Report Number(s):
- PPPL-2329

ON: DE86011364

- DOE Contract Number:
- AC02-76CH03073

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; TOKAMAK DEVICES; HELICITY; MAGNETIC FLUX; PLASMA INSTABILITY; TEARING INSTABILITY; TURBULENCE; CLOSED PLASMA DEVICES; INSTABILITY; PARTICLE PROPERTIES; PLASMA MACROINSTABILITIES; THERMONUCLEAR DEVICES; 700107* - Fusion Energy- Plasma Research- Instabilities

### Citation Formats

```
Boozer, A.H..
```*Helicity content and tokamak applications of helicity*. United States: N. p., 1986.
Web. doi:10.2172/5628601.

```
Boozer, A.H..
```*Helicity content and tokamak applications of helicity*. United States. doi:10.2172/5628601.

```
Boozer, A.H.. Thu .
"Helicity content and tokamak applications of helicity". United States.
doi:10.2172/5628601. https://www.osti.gov/servlets/purl/5628601.
```

```
@article{osti_5628601,
```

title = {Helicity content and tokamak applications of helicity},

author = {Boozer, A.H.},

abstractNote = {Magnetic helicity is approximately conserved by the turbulence associated with resistive instabilities of plasmas. To generalize the application of the concept of helicity, the helicity content of an arbitrary bounded region of space will be defined. The definition has the virtues that both the helicity content and its time derivative have simple expressions in terms of the poloidal and toroidal magnetic fluxes, the average toroidal loop voltage and the electric potential on the bounding surface, and the volume integral of E-B. The application of the helicity concept to tokamak plasmas is illustrated by a discussion of so-called MHD current drive, an example of a stable tokamak q profile with q less than one in the center, and a discussion of the possibility of a natural steady-state tokamak due to the bootstrap current coupling to tearing instabilities.},

doi = {10.2172/5628601},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Thu May 01 00:00:00 EDT 1986},

month = {Thu May 01 00:00:00 EDT 1986}

}