Collective fast ion instability-induced losses in National Spherical Tokamak Experiment

A wide variety of fast ion driven instabilities are excited during neutral beam injection (NBI) in the National Spherical Torus Experiment (NSTX) [Nucl. Fusion 40, 557 (2000)] due to the large ratio of fast ion velocity to Alfven velocity, Vfast∕VAlfven, and high fast ion beta. The ratio Vfast∕VAlfven in ITER [Nucl. Fusion 39, 2137 (1999)] and NSTX is comparable. The modes can be divided into three categories: chirping energetic particle modes (EPM) in the frequency range 0 to 120kHz, the toroidal Alfven eigenmodes (TAE) with a frequency range of 50kHz to 200kHz, and the compressional and global Alfven eigenmodes (CAE and GAE, respectively) between 300kHz and the ion cyclotron frequency. Fast ion driven modes are of particular interest because of their potential to cause substantial fast ion losses. In all regimes of NBI heated operation we see transient neutron rate drops, correlated with bursts of TAE or fishbone-like EPMs. The fast ion loss events are predominantly correlated with the EPMs, although ...

[1]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[2]  M. Rosenbluth,et al.  Excitation of internal kink modes by trapped energetic beam ions , 1984 .

[3]  J. Menard,et al.  Phenomenology of compressional Alfvén eigenmodes , 2004 .

[4]  T. Ozeki,et al.  Fast particle experiments in JT-60U , 2000 .

[5]  S. Sharapov,et al.  Beta-dependence of energetic particle-driven instabilities in spherical tokamaks , 2004 .

[6]  D. Stutman,et al.  Wave driven fast ion loss in the national spherical torus experiment , 2003 .

[7]  E. J. Strait,et al.  An investigation of beam driven Alfvén instabilities in the DIII-D tokamak , 1991 .

[8]  Fulvio Zonca,et al.  Theory of toroidal Alfvén modes excited by energetic particles in tokamaks , 1996 .

[9]  M. Viola,et al.  Exploration of spherical torus physics in the NSTX device , 2000 .

[10]  R. Gruber,et al.  Excitation of global eigenmodes of the Alfven wave in Tokamaks , 1982 .

[11]  C. A. Phillips.  Princeton Plasma Physics Laboratory , 1986 .

[12]  N. Gorelenkov,et al.  Excitation of Alfvén cyclotron instability by charged fusion products in tokamaks , 1995 .

[13]  B. Coppi,et al.  High energy components and collective modes in thermonuclear plasmas , 1986 .

[14]  E. Fredrickson,et al.  Bounce precession fishbones in the national spherical torus experiment , 2003 .

[15]  Chio Cheng,et al.  Alfven cyclotron instability and ion cyclotron emission , 1995 .

[16]  Robert J. Goldston,et al.  Theory of mode-induced beam-particle loss in tokamaks , 1983 .

[17]  S. Mahajan,et al.  Spectrum of compressional Alfvén waves , 1983 .

[18]  B. Alper,et al.  Monitoring Alfvén cascades with interferometry on the JET Tokamak. , 2004, Physical review letters.

[19]  L. L. Lao,et al.  Equilibrium properties of spherical torus plasmas in NSTX , 2001 .

[20]  G. L. Chen,et al.  Discrete Alfvén eigenmode spectrum in magnetohydrodynamics , 1982 .

[21]  M. Pekker,et al.  Numerical simulation of bump‐on‐tail instability with source and sink , 1995 .

[22]  M. S. Chance,et al.  Low-n shear Alfven spectra in axisymmetric toroidal plasmas , 1986 .

[23]  Chio Cheng,et al.  Fast particle destabilization of toroidal Alfven eigenmodes , 1995 .

[24]  G. L. Chen,et al.  Kinetic description of Alfven wave heating , 1982 .

[25]  R. Bell,et al.  Observation of compressional Alfvén modes during neutral-beam heating on the national spherical torus experiment. , 2001, Physical review letters.

[26]  Bell,et al.  Nature of monster sawteeth and their relationship to Alfven instabilities in tokamaks , 2000, Physical review letters.

[27]  R. Grimm,et al.  Study of high-beta magnetohydrodynamic modes and fast-ion losses in PDX , 1983 .

[28]  H. Berk,et al.  Spontaneous hole-clump pair creation in weakly unstable plasmas [Physics Letters A 234 (1997) 213] , 1997 .

[29]  G. Fu,et al.  Thermonuclear instability of global-type shear Alfven modes , 1990 .

[30]  M. Pekker,et al.  Spontaneous hole–clump pair creation , 1999 .

[31]  J. Tataronis,et al.  The shear Alfvén continuous spectrum of axisymmetric toroidal equilibria in the large aspect ratio limit , 1982, Journal of Plasma Physics.

[32]  Liu Chen,et al.  Theory of magnetohydrodynamic instabilities excited by energetic particles in tokamaks , 1994 .

[33]  Paul,et al.  Excitation of toroidal Alfvén eigenmodes in TFTR. , 1991, Physical review letters.

[34]  E. Belova,et al.  Compressional Alfvén eigenmode instability in NSTX , 2002 .

[35]  M. Mauel,et al.  Suppression of nonlinear frequency-sweeping of resonant interchange modes in a magnetic dipole with applied radio frequency fields , 2003 .

[36]  L. Lao,et al.  Reconstruction of current profile parameters and plasma shapes in tokamaks , 1985 .