Plasma Current Profile Shaping with RF-Current Drive

  • David A. Ehst
  • Kenneth EvansJr.
Part of the Ettore Majorana International Science Series book series (EMISS)


As our understanding of rf current drive in tokamaks improves we should seek to employ this technique in the optimum fashion to enhance the attractiveness of tokamak reactor economics. Work at ANL throughout the past year has identified several areas in which the tokamak concept could be improved relative to the STARFIRE design.1,2 Many of these improvements derive from the possibility of operating in the second stability regime.3,4 In particular, we note that plasmas with toroidal betas in excess of twenty per cent have been found theoretically stable to ideal MHD modes in high aspect ratio tokamaks with quite modest toroidal currents. In our opinion a tokamak reactor may be most attractive if it embodies the four following characteristics. First, high beta is essential to reducing cost, since considerable capital is invested in the large toroidal field magnets. Second, high aspect ratio (A ≳ 5) will facilitate the use of efficient fast wave current drive5,6 and could simplify reactor maintenance operations. Third, low toroidal current (≲5 MA) will greatly reduce the cost of the equilibrium field coil (EFC) system and attendant start-up power supplies and will reduce the consequences of a plasma disruption. Fourth, steady state operation is likely to reduce costs and increase reliability relative to pulsed operating cycles.


Magnetic Axis Current Drive Current Density Profile Local Pressure Gradient Lower Hybrid Current Drive 
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Copyright information

© Springer Science+Business Media New York 1986

Authors and Affiliations

  • David A. Ehst
    • 1
  • Kenneth EvansJr.
    • 1
  1. 1.Fusion Power ProgramArgonne National LaboratoryArgonneUSA

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