Coaxial helicity injection in open-flux low-aspect-ratio toroidal discharges

2007 ◽  
Vol 14 (11) ◽  
pp. 112511 ◽  
Author(s):  
A. J. Redd ◽  
T. R. Jarboe ◽  
B. A. Nelson ◽  
R. G. O’Neill ◽  
R. J. Smith
Keyword(s):  
Aspect Ratio ◽  
Helicity Injection ◽  
Low Aspect Ratio ◽  
Coaxial Helicity Injection ◽  
Open Flux

Low Aspect Ratio Tokamak Formation and Sustainment by Coaxial Helicity Injection Current Drive

1995 ◽  
Vol 27 (3T) ◽  
pp. 333-336
Author(s):  
B. A. Nelson ◽  
T. R. Jarboe ◽  
D. J. Orvis ◽  
A. K. Martin ◽  
J. Xie ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Current Drive ◽  
Injection Current ◽  
Helicity Injection ◽  
Low Aspect Ratio ◽  
Coaxial Helicity Injection

Formation and sustainment of a low‐aspect ratio tokamak by coaxial helicity injection

1995 ◽  
Vol 2 (6) ◽  
pp. 2337-2341 ◽  
Author(s):  
B. A. Nelson ◽  
T. R. Jarboe ◽  
A. K. Martin ◽  
D. J. Orvis ◽  
J. Xie ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Helicity Injection ◽  
Low Aspect Ratio ◽  
Coaxial Helicity Injection

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.

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