Electron-cyclotron-current-drive efficiency in DEMO plasmas

The achievable efficiency for external current drive through electron-cyclotron waves in a demonstration tokamak reactor is investigated. Two possible reactor designs, one for steady state and one for pulsed operation, are considered. Beam propagation, absorption and current drive are modelled employing the beam-tracing technique and including momentum conservation in electron–electron collisions. It is found that for midplane injection the achievable current drive efficiency is limited by second-harmonic absorption at levels consistent with previous studies. Higher efficiencies can be achieved by injecting the beams from the top of the machine, exploiting wave absorption by more energetic (less collisional) electrons. Current drive efficiencies competitive with those usually obtained by neutral beam current drive are reported. These optimum efficiencies are found for frequencies around 230 GHz and 290 GHz for the steady-state and the pulsed DEMO, supposed to operate at a magnetic field B = 5.84 T and B = 7.45 T, respectively.

[1]  E. G. Hope,et al.  Frequency of the Hydrogen Maser , 1971, Nature.

[2]  Allen H. Boozer,et al.  Creating an asymmetric plasma resistivity with waves , 1980 .

[3]  Charles F. F. Karney,et al.  Currents driven by electron cyclotron waves , 1981 .

[4]  Thomas M. Antonsen,et al.  Radio frequency current generation by waves in toroidal geometry , 1982 .

[5]  R. Cano,et al.  Electron cyclotron emission and absorption in fusion plasmas , 1983 .

[6]  Kjell Rönnmark.  Kinetic theory of plasma waves , 1985 .

[7]  S. Wolfe,et al.  A new look at density limits in tokamaks , 1988 .

[8]  Physical Review Letters 63 , 1989 .

[9]  Harvey,et al.  Power dependence of electron-cyclotron current drive for low- and high-field absorption in tokamaks. , 1989, Physical review letters.

[10]  F. A. Haas,et al.  Reviews of Plasma Physics, Volumes 14–16, edited by B. B. Kadomtsev. Consultants Bureau1989–1990, $85, $95 and $89.50. , 1990, Journal of Plasma Physics.

[11]  Linear interaction of electron cyclotron waves with a suprathermal electron tail , 1990 .

[12]  V. Erckmann,et al.  Electron cyclotron resonance heating and current drive in toroidal fusion plasmas , 1994 .

[13]  P. Stott,et al.  Plasma Physics and Controlled Fusion Conference: Focussing on Tokamak Research , 1995 .

[14]  Sergei Kasilov,et al.  Passive cyclotron current drive efficiency for relativistic toroidal plasmas , 1996 .

[15]  C. D. Warrick,et al.  Electron cyclotron heating and current drive in ITER , 1997 .

[16]  E Egbert Westerhof,et al.  Wave propagation through an electron cyclotron resonance layer , 1997 .

[17]  G. V. Pereverzev,et al.  Beam tracing in inhomogeneous anisotropic plasmas , 1998 .

[18]  T. C. Luce,et al.  Electron cyclotron current drive efficiency in general tokamak geometry , 2003 .

[19]  G. Giruzzi,et al.  GENERATION OF LOCALIZED NONINDUCTIVE CURRENT BY ELECTRON CYCLOTRON WAVES ON THE DIII-D TOKAMAK , 1999 .

[20]  Current Drive.  Chapter 6: Plasma auxiliary heating and current drive , 1999 .

[21]  Current Drive.  ITER Physics Basis Chapter 6: Plasma auxiliary heating and current drive , 2000 .

[22]  A. G. Peeters,et al.  The bootstrap current and its consequences , 2000 .

[23]  G. V. Pereverzev,et al.  TORBEAM, a beam tracing code for electron-cyclotron waves in tokamak plasmas , 2001 .

[24]  G. V. Pereverzev,et al.  EC Beam Tracing in Fusion Plasmas , 2001 .

[25]  T. C. Luce,et al.  Applications of high-power millimeter waves in fusion energy research , 2002 .

[26]  R. Prater,et al.  Heating and current drive by electron cyclotron waves , 2003 .

[27]  F. Ryter,et al.  Density peaking, anomalous pinch, and collisionality in tokamak plasmas. , 2003, Physical review letters.

[28]  A. Manini,et al.  The improved H-mode at ASDEX Upgrade: a candidate for an ITER hybrid scenario , 2005 .

[29]  G. V. Pereverzev,et al.  Theoretical predictions of the density profile in a tokamak reactor , 2005 .

[30]  E. Joffrin,et al.  Chapter 6: Steady state operation , 2007 .

[31]  C. Angioni,et al.  Density profile peaking in low collisionality H-modes: comparison of Alcator C-Mod data to ASDEX Upgrade/JET scalings , 2007 .

[32]  K. Ikeda.  Progress in the ITER Physics Basis , 2007 .

[33]  J. Stober,et al.  The performance of improved H-modes at ASDEX Upgrade and projection to ITER , 2007 .

[34]  Daniela Farina,et al.  A Quasi-Optical Beam-Tracing Code for Electron Cyclotron Absorption and Current Drive: GRAY , 2007 .

[35]  J. Stober,et al.  Extrapolation of ASDEX Upgrade H-mode discharges to ITER , 2009 .

[36]  Nikolai B. Marushchenko,et al.  Electron cyclotron current drive calculated for ITER conditions using different models , 2008 .

[37]  Olivier Sauter,et al.  Physics analysis of the ITER ECW system for optimized performance , 2008 .

[38]  F. Imbeaux,et al.  Analysis of DEMO scenarios with the CRONOS suite of codes , 2008 .

[39]  Daniela Farina,et al.  Relativistic Dispersion Relation of Electron Cyclotron Waves , 2008 .

[40]  N. Kobayashi,et al.  Progress of high power 170 GHz gyrotron in JAEA , 2009 .

[41]  C. D. Beidler,et al.  Current Drive Calculations with an Advanced Adjoint Approach , 2009 .

[42]  Nikolai B. Marushchenko,et al.  Corrections to the paper ‘electron cyclotron current drive calculated for ITER conditions using different models’ (2008 Nucl. Fusion 48 054002) , 2009 .

[43]  G. V. Pereverzev,et al.  Validation of the paraxial beam-tracing method in critical cases , 2009 .

[44]  H. Zohm,et al.  On the Minimum Size of DEMO , 2010 .

[45]  Omar Maj,et al.  Effects of aberration on paraxial wave beams: beam tracing versus quasi-optical solutions , 2010 .

[46]  David Ward,et al.  On the heating mix of ITER , 2010 .

[47]  David Ward,et al.  The physics of DEMO , 2010 .

[48]  Winfried Kernbichler,et al.  Electron cyclotron current drive in low collisionality limit: On parallel momentum conservation , 2011 .

[49]  Lorenzo Figini,et al.  Potential of the ITER electron cyclotron equatorial launcher for heating and current drive at nominal and reduced fields , 2012 .

[50]  Boris B. Kadomtsev,et al.  Reviews of Plasma Physics , 2012 .

[51]  D. V. Eester,et al.  Kinetic Theory of Plasma Waves , 2012 .

[52]  R. H. Bulmer,et al.  Sustained Spheromak Physics Experiment (SSPX): design and physics results , 2012 .