Alpha effect of Alfvén waves and current drive in reversed-field pinches

1998 ◽  
Vol 5 (3) ◽  
pp. 553-555 ◽  
Author(s):  
C. Litwin ◽  
S. C. Prager
Keyword(s):  
Alfven Waves ◽  
Current Drive ◽  
Alfvén Waves ◽  
Alpha Effect ◽  
Reversed Field

Current drive by Alfvén waves in elongated cross-section tokamak

1997 ◽  
Vol 4 (10) ◽  
pp. 3635-3643 ◽  
Author(s):  
V. S. Tsypin ◽  
A. G. Elfimov ◽  
F. M. Nekrasov ◽  
C. A. de Azevedo ◽  
A. S. de Assis
Keyword(s):  
Cross Section ◽  
Alfven Waves ◽  
Current Drive ◽  
Alfvén Waves

Role of trapped and circulating particles in inducing current drive and radial electric field by Alfvén waves in tokamaks

2002 ◽  
Vol 67 (5) ◽  
pp. 301-308 ◽  
Author(s):  
V. S. TSYPIN ◽  
R. M. O. GALVÃO ◽  
I. C. NASCIMENTO ◽  
M. TENDLER ◽  
J. H. F. SEVERO ◽  
...  
Keyword(s):  
Electric Field ◽  
Radial Electric Field ◽  
Alfven Waves ◽  
Current Drive ◽  
Alfvén Waves ◽  
Trapped Particles ◽  
Transport Barriers

Absorption by trapped particles is supposed to seriously hinder current drive by Alfvén waves. However, it is shown in this paper that the same effect is rather beneficial for the emergence of the radial electric field induced by these waves, which is important for creating and maintaining transport barriers in tokamaks.

Current Drive by Alfvén Waves in Elongated Cross Section Tokamak

1998 ◽  
pp. 421-424
Author(s):  
V. Tsypin ◽  
A. Elfimov ◽  
M. Tendler ◽  
F. Nekrasov ◽  
C. De Azevedo ◽  
...  
Keyword(s):  
Cross Section ◽  
Alfven Waves ◽  
Current Drive ◽  
Alfvén Waves

Non-inductive current drive via helicity injection by Alfvén waves in low-aspect-ratio tokamaks

1996 ◽  
Vol 56 (1) ◽  
pp. 149-174 ◽  
Author(s):  
S. Cuperman ◽  
C. Bruma ◽  
K. Komoshvili
Keyword(s):  
Magnetic Field ◽  
Aspect Ratio ◽  
Alfven Waves ◽  
Current Drive ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Drive Power ◽  
Helicity Injection ◽  
Low Aspect Ratio ◽  
Optimal Current

A theoretical investigation of radio-frequency (RF) current drive via helicity injection in low aspect ratio tokamaks is carried out. A current-carrying cylindrical plasma surrounded by a helical sheet-current antenna and situated inside a perfectly conducting shell is considered. Toroidal features of low-aspect-ratio tokamaks are simulated by incorporating the following effects: (i) arbitrarily small aspect ratio, Ro/a ≡1/∈; (ii) strongly sheared equilibrium magnetic field; and (iii) relatively large poloidal component of the equilibrium magnetic field. This study concentrates on the Alfvén continuum, i.e. the case in which the wave frequency satisfies the condition , where is an eigenfrequency of the shear Alfven wave (SAW). Thus, using low-β magneto- hydrodynamics, the wave equation with correct boundary (matching) conditions is solved, the RF field components are found, and subsequently current drive, power deposition and efficiency are computed. The results of our investigation clearly demonstrate the possibility of generation of RF-driven currents via helicity injection by Alfvén waves in low-aspect-ratio tokamaks, in the SAW mode. A special algorithm is developed that enables one to select the antenna parameters providing optimal current drive efficiency.

The alpha-effect generated by random Alfven waves in a stratified atmosphere and particle acceleration

1987 ◽  
Vol 323 ◽  
pp. 414
Author(s):  
Tomikazu Namikawa ◽  
Hiromitsu Hamabata ◽  
Hiroyuki Wada
Keyword(s):  
Particle Acceleration ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Alpha Effect

Kinetic theory of Alfvén waves in plasmas with force-free currents

1991 ◽  
Vol 45 (2) ◽  
pp. 213-228 ◽  
Author(s):  
I. J. Donnelly ◽  
B. E. Clancy
Keyword(s):  
Kinetic Theory ◽  
Small Amplitude ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Larmor Radius ◽  
Alfvén Waves ◽  
Plasma Current ◽  
Theory Analysis ◽  
Wave Heating ◽  
Reversed Field

Equations are derived for the kinetic-theory analysis of small-amplitude Alfvén waves in cylindrical plasmas carrying force-free currents. The equations, which include ion Larmor-radius effects to second order, are applicable to reversed-field pinches as well as to tokamaks. Fourier mode amplitudes are derived for model antennas with radial current feeds, and a quantitative analysis is made of the antenna resistance and the wave density fields in a small tokamak during Alfvén-wave heating. The effect of the plasma current on the wave thermal energy flux is discussed.

Sign in / Sign up

Export Citation Format

Share Document