Gradient length driven electron heat transport study in modulated electron cyclotron heating FTU tokamak
Gradient length driven electron heat transport study in modulated electron cyclotron heating FTU tokamak
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DOI：
10.1088/0029-5515/42/9/310
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发表时间：
2002-09
期刊：
影响因子：
3.3
通讯作者：
A. Jacchia;F. Luca;S. Cirant;C. Sozzi;G. Bracco;A. Bruschi;P. Buratti;S. Podda;O. Tudisco
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文献类型：
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作者：
A. Jacchia;F. Luca;S. Cirant;C. Sozzi;G. Bracco;A. Bruschi;P. Buratti;S. Podda;O. Tudisco
采用调制电子回旋加热（MECH）方法研究了FTU托卡马克在电流上升放电中的扰动和稳态热输运。微扰和稳态传输实验与电子热传输是一致的，当电子温度梯度长度达到阈值1/LTc时，电子热传输从低值切换到高值。阈值1/LTc被示出为与比率s/q成比例。将实验结果与基于阈值梯度长度LTc（1/LT = 1/2）假设的经验模型的预测进行比较。|特/特|），在电子温度Te下，电子热扩散率χe从低值切换到高值。假设电子扩散率为χPB = χ0 + α Te 3/2（1/LT-1/LTc）1/2，对稳态和MECH的等离子体响应进行建模;这里Te 3/2反映了陀螺玻姆假设，χ0表示1/LT 1/LTc的热输运，模拟可能由于电子温度梯度（ETG）模式引起的额外输运。与ETG阈值一致，1/LTc与磁剪切s相关。
Perturbative and steady-state heat transport of FTU tokamak in current ramp-up discharges are investigated by means of modulated electron cyclotron heating (MECH). Perturbative and steady-state transport experiments are coherent with an electron heat transport which switches from low to high values when electron temperature gradient length reaches a threshold value 1/LTc. The threshold value 1/LTc is shown to be proportional to the ratio s/q. The experimental findings are compared to predictions of an empirical model based on the assumption of a threshold gradient length, LTc (1/LT = |∇Te/Te|), in the electron temperature Te below which electron thermal diffusivity, χe, switches from low to high values. Plasma responses to steady state and MECH are modelled assuming the electron diffusivity as χPB = χ0 + αTe3/2(1/LT-1/LTc)1/2; here Te3/2 reflects the gyro-Bohm assumption, χ0 represents the heat transport for 1/LT 1/LTc, mimics an extra transport possibly due to electron temperature gradient (ETG) modes. In agreement with ETG threshold 1/LTc is shown to be correlated with the magnetic shear s.