Citation
Schalit, Mark Alan (1989) Oscillatingfield currentdrive schemes for tokamaks. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd02132007141701
Abstract
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A novel currentdrive scheme for steadystate tokamak operation is investigated in which external coils are applied to induce timeperiodic fluidtype, fluctuations within the plasma; a nonlinear interaction between these fluctuations results in a timeaveraged EMF, which maintains the largescale magnetic field against Ohmic dissipation. Analytical and numerical modeling of this currentdrive scheme is presented for lowfrequency schemes (where the nonlinear <[u]x[b]]> EMF is dominant) and for higherfrequency schemes (where the <[ j]x[b]> Hall EMF is dominant). The Hall EMF is dominant at frequencies well above the ioncyclotron frequency (referred to the strength of the static axial field)  except in the case of the rotamak, where the oscillating electric field is in the same direction as the static axial field. A figureofmerit for these currentdrive schemes is the ratio of the strength of the static axial current to the strength of the oscillating current. This ratio is always much less than unity in all standard MHD calculations. As the electronion collision frequency vanishes, the ratio approaches infinity for the case of the rotamak. The ratio also approaches infinity for the m = 1 analogue of the rotamak  but only in the restrictive case where the static axial field becomes vanishingly small and where the DC magnetic fields are a small fraction of the AC magnetic fields. For the m = 1 analogue, the currents are confined to a skin layer as the axial field becomes very large, with the ratio of DC current strength to the oscillating current strength approaching unity. The analysis presented here is compared and contrasted with existing theories and to a number of recent experiment
Item Type:  Thesis (Dissertation (Ph.D.)) 

Subject Keywords:  Applied Physics 
Degree Grantor:  California Institute of Technology 
Division:  Engineering and Applied Science 
Major Option:  Applied Physics 
Thesis Availability:  Restricted to Caltech community only 
Research Advisor(s): 

Thesis Committee: 

Defense Date:  16 February 1989 
Record Number:  CaltechETD:etd02132007141701 
Persistent URL:  http://resolver.caltech.edu/CaltechETD:etd02132007141701 
Default Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided. 
ID Code:  627 
Collection:  CaltechTHESIS 
Deposited By:  Imported from ETDdb 
Deposited On:  12 Mar 2007 
Last Modified:  24 Jan 2013 22:07 
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