One-dimensional modelling of limit-cycle oscillation and H-mode power scaling

Nuclear Fushion

article

Xingquan Wu¹  Guosheng Xu¹  Baonian Wan¹  Jens Juul Rasmussen²  Volker Naulin²  Anders Henry Nielsen² 

[1] Institute of Plasma Physics, Chinese Academy of Sciences;Department of Physics, Technical University of Denmark

关键词: L–H transition;    power threshold scaling;    limit-cycle oscillation;    E × B flow shear;   

DOI  :  10.1088/0029-5515/55/5/053029

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

To understand the connection between the dynamics of microscopic turbulence and the macroscale power scaling in the L–I–H transition in magnetically confined plasmas, a new time-dependent, one-dimensional (in radius) model has been developed. The model investigates the radial force balance equation at the edge region of the plasma and applies the quenching effect of turbulence via the E  ×  B flow shear rate exceeding the shear suppression threshold. By slightly ramping up the heating power, the spatio-temporal evolution of turbulence intensity, density and pressure profiles, poloidal flow and E  ×  B flow self-consistently displays the L–H transition with an intermediate phase (I-phase) characterized by limit-cycle oscillations. Since the poloidal flow is partially damped to the neoclassical flow in the edge region, the numerical results reveal two different oscillation relationships between the E  ×  B flow and the turbulence intensity depending on which oscillation of the diamagnetic flow or poloidal flow is dominant. Specifically, by including the effects of boundary conditions of density and temperature, the model results in a linear dependence of the H-mode access power on the density and magnetic field. These results imply that the microscopic turbulence dynamics and the macroscale power scaling for the L–H transition are strongly connected.

【 授权许可】

Unknown