Separation of transport in slow and fast time-scales using modulated heat pulse experiments (hysteresis in flux explained)

Nuclear Fushion

article

M. van Berkel¹  G. Vandersteen²  H.J. Zwart³  G.M.D. Hogeweij¹  J. Citrin¹  E. Westerhof¹  D. Peumans²  M.R. de Baar¹ 

[1] DIFFER-Dutch Institute for Fundamental Energy Research;Department of Fundamental Electricity and Instrumentation, Vrije Universiteit Brussel;Department of Mechanical Engineering, Eindhoven University of Technology, Dynamics & Control Group;Department of Applied Mathematics, University of Twente;Department of Mechanical Engineering, Eindhoven University of Technology, Control Systems Technology Group

关键词: perturbative experiments;    electron transport;    non-local;    heat pulse;    modulation;    turbulence;    electron cyclotron heating;   

DOI  :  10.1088/1741-4326/aadc17

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Old and recent experiments show that there is a direct response to the heating power of transport observed in modulated ECH experiments both in tokamaks and stellarators. This is most apparent for modulated experiments in the Large Helical Device (LHD) and in Wendelstein 7 advanced stellarator (W7-AS). In this paper we show that: (1) this power dependence can be reproduced by linear models and as such hysteresis (in flux) has no relationship to hysteresis as defined in the literature; (2) observations of 'hysteresis' (in flux) and a direct response to power can be perfectly reproduced by introducing an error in the estimated deposition profile as long as the errors redistribute the heat over a large radius; (3) non-local models depending directly on the heating power can also explain the experimentally observed Lissajous curves (hysteresis); (4) how non-locality and deposition errors can be recognized in experiments and how they affect estimates of transport coefficients; (5) from a linear perturbation transport experiment, it is not possible to discern deposition errors from non-local fast transport components (mathematically equivalent). However, when studied over different operating points non-linear-non-local transport models can be derived which should be distinguishable from errors in the deposition profile. To show all this, transport needs to be analyzed by separating the transport in a slow (diffusive) time-scale and a fast (heating/non-local) time-scale, which can only be done in the presence of perturbations.

【 授权许可】

Unknown