Fluctuation characteristics and transport properties of collisionless trapped electron mode turbulence

The collisionless trapped electron mode turbulence is investigated by global gyrokinetic particle simulation. The zonal flow dominated by low frequency and short wavelength acts as a very important saturation mechanism. The turbulent eddies are mostly microscopic, but with a significant portion in the mesoscale. The ion heat transport is found to be diffusive and follows the local radial profile of the turbulence intensity. However, the electron heat transport demonstrates some nondiffusive features and only follows the global profile of the turbulence intensity. The nondiffusive features of the electron heat transport is further confirmed by nonlognormal statistics of the flux-surface-averaged electron heat flux. The radial and time correlation functions are calculated to obtain the radial correlation length and autocorrelation time. Characteristic time scale analysis shows that the zonal flow shearing time and eddy turnover time are very close to the effective decorrelation time, which suggests that the trapped electrons move with the fluid eddies. The fluidlike behaviors of the trapped electrons and the persistence of the mesoscale eddies contribute to the transition of the electron turbulent transport from gyro-Bohm scaling to Bohm scaling when the device size decreases.

[1]  Frank Jenko,et al.  Electron temperature gradient driven turbulence , 1999 .

[2]  Lin,et al.  Method for solving the gyrokinetic Poisson equation in general geometry. , 1995, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[3]  T. Hahm,et al.  Weak turbulence theory of collisionless trapped electron driven drift instability in tokamaks , 1991 .

[4]  T. Hahm,et al.  Generalized expression for polarization density , 2009 .

[5]  Scott E. Parker,et al.  Nonlinear saturation of collisionless trapped electron mode turbulence: Zonal flows and zonal densitya) , 2008 .

[6]  W. Lee,et al.  Partially linearized algorithms in gyrokinetic particle simulation , 1993 .

[7]  Paul W. Terry,et al.  Influence of sheared poloidal rotation on edge turbulence , 1990 .

[8]  Zhihong Lin,et al.  Properties of microturbulence in toroidal plasmas with reversed magnetic shear , 2009 .

[9]  A. Aydemir.  A unified Monte Carlo interpretation of particle simulations and applications to non-neutral plasmas , 1994 .

[10]  I. Holod,et al.  Statistical analysis of fluctuations and noise-driven transport in particle-in-cell simulations of plasma turbulence , 2007 .

[11]  H. Sanuki,et al.  Multiple eigenmodes of geodesic acoustic mode in collisionless plasmas , 2006 .

[12]  T. S. Hahm,et al.  Turbulence spreading and transport scaling in global gyrokinetic particle simulations , 2004 .

[13]  S. Parker,et al.  A fully nonlinear characteristic method for gyrokinetic simulation , 1993 .

[14]  F. Leuterer,et al.  Experimental study of trapped-electron-mode properties in tokamaks: threshold and stabilization by collisions. , 2005, Physical review letters.

[15]  Z. Lin,et al.  Wave-particle decorrelation and transport of anisotropic turbulence in collisionless plasmas. , 2007, Physical review letters.

[16]  J. Kinsey,et al.  Core Barrier Formation Near Integer q Surfaces in DIII-D , 2005 .

[17]  M. Rosenbluth,et al.  Nonlinear saturation of the dissipative trapped-electron instability , 1977 .

[18]  Ihor Holod,et al.  Iop Publishing Plasma Physics and Controlled Fusion Global Gyrokinetic Particle Simulations with Kinetic Electrons , 2022 .

[19]  R. Waltz,et al.  Numerical experiments on the drift wave–zonal flow paradigm for nonlinear saturation , 2008 .

[20]  F. Jenko,et al.  Nonlinear saturation of trapped electron modes via perpendicular particle diffusion. , 2008, Physical review letters.

[21]  P. T. Bonoli,et al.  Role of trapped electron mode turbulence in internal transport barrier control in the Alcator C-Mod Tokamak , 2004 .

[22]  P. Catto,et al.  Arbitrary poloidal gyroradius effects in tokamak pedestals and transport barriers , 2008 .

[23]  W. Lee,et al.  Gyrokinetic Particle Simulation Model , 1987 .

[24]  Laurent Villard,et al.  Nonlinear low noise particle-in-cell simulations of electron temperature gradient driven turbulence , 2007 .

[25]  E. Frieman,et al.  Nonlinear gyrokinetic equations for low-frequency electromagnetic waves in general plasma equilibria , 1981 .

[26]  T. Hahm,et al.  Turbulent transport reduction by zonal flows: massively parallel simulations , 1998, Science.

[27]  Peter J. Catto,et al.  Short wavelength effects on the collisionless neoclassical polarization and residual zonal flow level , 2006 .

[28]  Zhihong Lin,et al.  A fluid-kinetic hybrid electron model for electromagnetic simulations , 2001 .

[29]  X. Xu,et al.  TEMPEST simulations of collisionless damping of the geodesic-acoustic mode in edge-plasma pedestals. , 2007, Physical review letters.

[30]  Mike Kotschenreuther,et al.  Comparison of initial value and eigenvalue codes for kinetic toroidal plasma instabilities , 1995 .

[31]  Charlson C. Kim,et al.  Comparisons and physics basis of tokamak transport models and turbulence simulations , 2000 .

[32]  John M. Dawson,et al.  Fluctuation-induced heat transport results from a large global 3D toroidal particle simulation model , 1996 .

[33]  W. W. Lee,et al.  Gyrokinetic approach in particle simulation , 1981 .

[34]  W. Tang,et al.  Destabilization of the trapped-electron mode by magnetic curvature drift resonances , 1976 .

[35]  Gyrokinetic particle simulations of toroidal momentum transport , 2008 .

[36]  T. Watari,et al.  Geodesic acoustic mode oscillation in the low frequency range , 2005 .

[37]  K. Tsang,et al.  Trapped electron instability in tokamaks: Analytic solution of the two‐dimensional eigenvalue problem , 1978 .

[38]  T. S. Hahm,et al.  Zonal flows in plasma—a review , 2005 .

[39]  R. Waltz,et al.  Studies of turbulence and transport in Alcator C-Mod ohmic plasmas with phase contrast imaging and comparisons with gyrokinetic simulations , 2009 .

[40]  R. A. Kolesnikov,et al.  On higher order corrections to gyrokinetic Vlasov―Poisson equations in the long wavelength limit , 2009 .

[41]  W. Dorland,et al.  Role of zonal flows in trapped electron mode turbulence through nonlinear gyrokinetic particle and continuum simulation , 2008 .

[42]  Zhihong Lin,et al.  Transport of energetic particles by microturbulence in magnetized plasmas. , 2008, Physical review letters.

[43]  K. H. Burrell,et al.  Flow shear induced fluctuation suppression in finite aspect ratio shaped tokamak plasma , 1995 .

[44]  Inverse energy transfer by near-resonant interactions with a damped-wave spectrum. , 2004, Physical review letters.

[45]  R. White,et al.  Excitation of zonal flow by drift waves in toroidal plasmas , 1999 .

[46]  W. Horton.  Drift waves and transport , 1999 .

[47]  Yasuhiro Idomura,et al.  Linear comparison of gyrokinetic codes with trapped electrons , 2007, Comput. Phys. Commun..

[48]  W. Dorland,et al.  Effects of finite poloidal gyroradius, shaping, and collisions on the zonal flow residual , 2007 .

[49]  Zhihong Lin,et al.  Turbulent transport of trapped-electron modes in collisionless plasmas. , 2009, Physical review letters.

[50]  J. Juul Rasmussen,et al.  Shear flow generation and energetics in electromagnetic turbulence , 2005 .

[51]  B. Coppi,et al.  New trapped-electron instability , 1974 .

[52]  Z. Lin,et al.  Size scaling of turbulent transport in magnetically confined plasmas. , 2002, Physical review letters.

[53]  J. W. Connor,et al.  Shear, periodicity, and plasma ballooning modes , 1978 .

[54]  J. Rasmussen,et al.  Turbulent flux and the diffusion of passive tracers in electrostatic turbulence , 2003 .

[55]  T. Hahm,et al.  Shearing rate of time-dependent E×B flow , 1999 .

[56]  W. Tang.  Microinstability theory in tokamaks , 1978 .

[57]  F. Parra,et al.  Limitations of gyrokinetics on transport time scales , 2008 .

[58]  A. Manini,et al.  Search for a critical electron temperature gradient in DIII-D L-mode discharges , 2005 .

[59]  R. Balescu,et al.  Lagrangian versus Eulerian correlations and transport scaling , 2004 .