Plasma shaping effects on the geodesic acoustic mode in the large orbit drift width limit

Gao, Zhe
September 2010
Physics of Plasmas;Sep2010, Vol. 17 Issue 9, p092503
Academic Journal
Plasma shaping effects on the geodesic acoustic mode (GAM) are revisited analytically in the large orbit drift width limit. Comparing with results from the small orbit drift width expansion method [Z. Gao et al., Phys. Plasmas 15, 074502 (2008)] the behavior of the real frequency is almost the same but the effect on the damping rate is different due to the change of dominant resonant mechanism, from low order harmonic transit resonance to high order harmonic resonance, or equivalently, to the magnetic drift resonance. As a result, although the GAM frequency decreases with an increasing elongation κ by dependence of [2/(κ2+1)]1/2, the damping is weakened mildly in the large orbit drift width limit, which is quite different from the result in the low small orbit drift limit, where the damping is enhanced exponentially with the decrease in frequency. Also, in the large orbit drift width limit, the dependence of the GAM damping rate on inverse aspect ratio [variant_greek_epsilon] is analytically obtained for the first time. As [variant_greek_epsilon] increases, the frequency behaves as a weakly decreasing parabola function of [variant_greek_epsilon], and the damping rate increases parabolically, but more rapidly than the frequency decreases. The GAM with longer radial wavelength is more easily damped by the finite aspect ratio effect. It is also found that the Shafranov shift gradient has the similar effect as the inverse aspect ratio.


Related Articles

  • Reduced fractional absorption and second harmonic emission in laser-produced plasmas. Ruhl, H.; Cairns, R.A. // Physics of Plasmas;Jun97, Vol. 4 Issue 6, p2246 

    Discusses reduced fractional absorption and second harmonic emission in laser-produced plasmas. Particle-in-cell and Vlasov simulations of the collective absorption of p-polarized intense laser light incident on a plasma; Fractional absorption decreasing with intensity for large angles of...

  • Damping of toroidal ion temperatue gradient modes. Sugama, H. // Physics of Plasmas;Sep99, Vol. 6 Issue 9, p3527 

    Examines the damping of toroidal ion temperature gradient (ITG) modes. Ion gyrokinetic equation; Time evolution of the toroidal ITG mode; Numerical solution for stable and unstable normal modes.

  • Evolution of the plasma rotation and the radial electric field for a toroidal plasma in the Pfirsch—Schlüter and plateau regimes subject to a biased electrode. Coronado, M.; Talmadge, J. N. // Physics of Fluids B: Plasma Physics;Apr93, Vol. 5 Issue 4, p1200 

    In this paper, the fluid equation approach is used to analyze the time evolution of the plasma rotation and the ambipolar electric field in a nonsymmetric toroidal plasma subject to an external biasing voltage induced by a probe. Under consideration is a plasma with low rotation speed in the...

  • Experimental evidence for spatial damping of left-hand circularly polarized waves in an electron cyclotron resonance region. Kaneko, T.; Murai, H.; Hatakeyama, R.; Sato, N. // Physics of Plasmas;May2001, Vol. 8 Issue 5, p1455 

    Selective launch, propagation, and absorption of right-hand (R) and left-hand (L) circularly polarized waves are investigated using an inhomogeneously magnetized plasma. When the R wave gets closer to the electron cyclotron resonance (ECR) point, the wave vanishes in the strong magnetic-field...

  • Comment on 'Alfven 'resonance' reconsidered: Exact equations for wave propagation across a cold... Ruderman, M.S.; Goossens, M.; Zhelyazkov, I. // Physics of Plasmas;Sep95, Vol. 2 Issue 9, p3547 

    Comments on the research 'Alfven 'resonance' reconsidered: Exact equations for wave propagation across a cold inhomogeneous plasma,' by P.M. Bellan, which appeared in the journal 'Physics of Plasmas.' Bellan's statements on problems associated with Alfven's resonance in magnetohydrodynamics;...

  • Influence of resonant magnetic perturbations on plasma edge turbulence. Castro, R.M.; Heller, M.V.A.P.; Caldas, I.L.; Brasilio, Z.A.; da Silva, R.P.; Nascimento, I.C. // Physics of Plasmas;Feb97, Vol. 4 Issue 2, p329 

    Reports on alterations on plasma-edge equilibrium profiles and on edge turbulence, and anomalous transport induced by resonant perturbing magnetic fields in the TBR tokamak. Computation of electrostatic edge parameters; Effects of the perturbation on the linear correlation between electrostatic...

  • Comment on 'On the Alfven resonance and its existence' [Phys. Plasmas 2, 340 (1995)]. Bellan, P.M. // Physics of Plasmas;Jan1996, Vol. 3 Issue 1, p435 

    Reacts to comments on a 1995 'Physics of Plasmas' paper regarding the validity of the Alfven resonance concept. Existence of the Alfven resonance in a magnetohydrodynamic (MHD); Real plasma versus MHD plasma; Ratio of thermal energy to magnetic energy.

  • Damping of the fast Alfvén wave in ion-cyclotron resonance heating. Chow, C.; Ram, A. K.; Bers, A. // Physics of Fluids B: Plasma Physics;Oct89, Vol. 1 Issue 10, p2018 

    The conditions are determined under which the damping of the fast Alfvén wave, used in the heating of tokamak plasmas, can be described by the geometrical optics approximations. Also, for these conditions, an analytic formula is derived, which explicitly determines the amount of energy that...

  • Response to Schalit and Bellan. Miller, R. L.; Chan, V. S.; Ohkawa, T. // Physics of Fluids B: Plasma Physics;Dec89, Vol. 1 Issue 12, p2534 

    The ac helicity effect discussed by Schalit and Bellan does not impact the current drive efficiency obtained by Ohkawa.


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics