Aachen PK 2003 – scientific programme

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P: Plasmaphysik

P 4: Poster I

P 4.18: Poster

Monday, March 17, 2003, 17:45–19:15, Foyer

Bernstein wave heating and current drive. — •Duncan McGregor¹, Alan Cairns Cairns¹, Chris Lashmore-Davies², and Abhay Ram³ — ¹School of Mathematics and Statistics,University of St Andrews, St Andrews KY16 9SS, UK — ²Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB, UK — ³Plasma Science and Fusion Center, MIT, Cambridge MA, USA

Bernstein wave heating and current drive. D E McGregor and R A Cairns, University of St Andrews, UK C N Lashmore-Davies, Euratom-UKAEA Fusion Association, Culham, UK A Ram, Plasma Science and Fusion Center, MIT, Cambridge MA, USA The O and X modes do not propagate beyond the edge of a spherical tokamak because of its low magnetic field. However, the electron Bernstein mode does propagate in low magnetic field, high density plasmas and is strongly damped when the wave frequency is close to a harmonic of the cyclotron frequency. Theoretical consideration of the propagation and damping of this wave is complicated by the fact that relativistic effects are important, as they are for the O and X modes, and also by the fact that the Bernstein mode has a short perpendicular wavelength so that expansion of the dispersion tensor in terms of the ratio of the perpendicular wavelength to the Larmor radius of a thermal particle is not valid. Using a relativistic dispersion relation which is valid for arbitrary perpendicular wavelength we shall present results on the propagation and absorption of Bernstein waves and estimates of current drive efficiency. Implications for the prospects of Bernstein wave heating and current drive in both present day spherical tokamaks and projected reactor size machines will be discussed.