EAST上低杂波驱动等离子体环向旋转实验研究

发布时间：2018-07-06 08:57

本文选题：托卡马克 + 电荷交换复合光谱诊断　；参考：《中国科学技术大学》2017年博士论文

【摘要】：等离子体旋转是提升等离子体比压极限、抑制湍流输运的有效方法。等离子体旋转还可以抑制大尺度的磁流体不稳定性,而旋转速度剪切在抑制微观不稳定性和反常输运中起到重要的作用。本论文工作参与并完成了 EAST上电荷交换复合光谱(Charge eXchange Recombination Spectroscopy,CXRS)诊断系统的搭建工作,包括系统安装、标定、调试优化以及数据后处理工作;基于EAST实验诊断和物理数据对EAST上低杂波驱动等离子体环向旋转展开了实验研究,为理解低杂波驱动等离子体旋转的物理机制积累了丰富的实验数据。本论文的主要内容概括如下:在EAST托卡马克装置上协助发展了一套CXRS诊断系统,用于等离子体旋转速度和离子温度测量,其观测范围覆盖了完整的等离子体剖面(对应大半径R=1 500-2370mm),空间分辨达到5-30mm(芯部到边界)时间分辨在30-50ms。在原有技术的基础上发展了新的CXRS空间和波长标定方法。对于测量观测位置与观测视线在托卡马克中详细的三维空间坐标的空间视线标定需求,发展了利用机械手臂进行测量空间位置的方法,结合束发射光谱多普勒频移的光谱测量方法进行空间标定,进一步提升了空间位置标定的精度。对波长标定采用标准灯和激光结合测量的方法提高J了实验运行期间波长标定的准确性和稳定性。基于电荷交换诊断原理对SOS软件的CX_Simu1ation模块进行升级,并分别模拟了有限束宽度、同向中性束左右两条束线同时注入以及塞曼效应对CXRS诊断测量的影响。模拟结果显示在等离子体参数剖面分布变化比较平缓时有限束宽度效应对CXRS测量的影响相对测量值是小量,而当等离子体参数出现明显的梯度时(例如存在内部输运垒时)有限束宽度效应将对测量产生比较大的影响。两条束线同时注入使得CXRS测量得到的温度和速度都小于原始真实值,但是在芯部影响较小可以忽略,在边界温度和速度的测量误差分别高达17%和25%。塞曼效应对于等离子体旋转速度测量没有太大的影响,对温度测量则有一定的影响,且影响从高场侧到低场侧逐渐变小。为了提高数据分析效率,编写了包括CXRS系统信息,标定结果,CCD数据采集等信息的CXSFIT接口程序,并应用CXSFIT软件处理CXRS实验数据获得EAST放电过程中离子温度和旋转速度的时空分布信息。针对射频波驱动等离子体旋转这一重要课题,对EAST上低杂波驱动等离子体旋转展开了实验研究,发现在目前EAST的运行区间内低杂波驱动等离子体旋转同电流方向变化,并且与初始等离子体旋转方向无关。等离子体旋转对低杂波的响应速度与电流密度对低杂波的响应速度相同慢于电子温度的升高和内能的增加,同时研究发现低杂波注入后旋转速度上升的时间慢于低杂波撤出后旋转速度下降的时间。为了研究不同参数对低杂波驱动旋转的影响进行了不同放电条件下的对比实验。实验结果显示4.6 GHz低杂波相对2.45 GHz低杂波对等离子体旋转速度的驱动效果更好的同时也具有更好的电子温度加热以及电流驱动效果。低杂波驱动旋转速度的变化值与低杂波功率成正比,与等离子体电流和等离子体密度成负相关的关系。另外对低杂波注入等离子体后的等离子体旋转速度剖面分布进行了仔细分析。发现低杂波注入等离子体后,旋转速度在整个剖面分布上并不同步变化,而是在低杂波功率沉积区域首先发生变化,而后变化传递到等离子体全剖面。对于一炮NBI背景等离子体下注入低杂波放电的研究中发现低杂波注入等离子体后旋转速度的变化存在两个阶段:在低杂波注入等离子体后100ms内,旋转速度总是先在低杂波功率沉积区域处向反电流方向变化。然后随着低杂波的继续持续注入在相同的位置处旋转速度开始向同电流方向变化随后变化传递到整个剖面。最后,根据观测到的实验现象定性的给出了一个简单的低杂波驱动等离子体旋转的物理模型:低杂波注入等离子体后,低杂波自身携带的动量迅速通过朗道阻尼传递给电子,随后又通过电子与离子间的碰撞传递给离子,这是一个快过程并在低杂波注入后短时间内驱动等离子体向反电流方向旋转。低杂波注入等离子体后会在其沉积位置处产生一个局域的径向电场,从而形成径向流结合极向磁场产生的电磁力慢慢在环向产生一个同电流方向的驱动力,并随着低杂波的持续注入而慢慢变大直到径向电荷平衡。而在该力慢慢变大而超过由低杂波动量注入产生的力时,环向力综合的效果变为驱动等离子体旋转向同电流方向变化;上述两种力均在低杂波沉积位置附近产生,最后通过动量输运(扩散项和箍缩项)将局域的变化传递到整个等离子体剖面,使得等离子体旋转在环向达到一个新的平衡。
[Abstract]:The plasma rotation is an effective method to increase the ratio of the plasma to the pressure limit and suppress the turbulent transport. The rotation of the plasma can also inhibit the large scale magnetohydrodynamic instability, and the rotational velocity shear plays an important role in inhibiting the micro instability and anomalous transport. The work of this paper has participated in and completed the charge exchange complex on EAST. The construction of the Charge eXchange Recombination Spectroscopy (CXRS) diagnostic system, including system installation, calibration, debug optimization and data post-processing; based on the experimental diagnosis and physical data of EAST, the experimental study of the low clutter driven plasma ring rotation on EAST is carried out to understand the low clutter driven plasma spin. The main contents of this paper are as follows: the main contents of this paper are as follows: a set of CXRS diagnostic systems was developed on the EAST Tokamak device to measure the rotational velocity of plasma and the measurement of ion temperature. The range of observation covers the complete plasma profile (corresponding to the large radius R=1 500-2370mm) and the spatial resolution. The time resolution of 5-30mm (core to boundary) has developed a new method of CXRS space and wavelength calibration on the basis of 30-50ms., which is based on the original technology. The method of measuring space position by measuring the observation position and the observation line of sight in the detailed three-dimensional space coordinates of the Tokamak is developed. The spectral measurement method of beam emission spectrum Doppler frequency shift is used to calibrate the space, and the accuracy of space location calibration is further improved. The accuracy and stability of wavelength calibration during J operation are improved by using standard light and laser combined measurement for wavelength calibration. Based on the principle of charge exchange diagnosis, the CX_Simu of SOS software The 1ation module is upgraded, and the finite beam width, the simultaneous injection of two beams with the same neutral beam and the effect of the Zeeman effect on the CXRS diagnosis are respectively simulated. The simulation results show that the effect of the finite beam width effect on the measurement of CXRS measurements is small when the profile of the plasma parameters is relatively slow. The effect of the limited beam width effect on the plasma parameters, such as the internal transport barrier, will have a larger effect on the measurement. The two beam line injection makes the temperature and velocity of the CXRS measurement less than the original true value, but the small influence on the core can be ignored and the measurement error at the boundary temperature and velocity is incorrect. The difference of the difference up to 17% and 25%. Zeeman effect has not much influence on the measurement of the velocity of plasma rotation. It has a certain influence on the temperature measurement, and the influence is gradually reduced from the high field side to the low field side. In order to improve the efficiency of data analysis, the CXSFIT interface program, including the information of the CXRS system, the calibration result, the CCD data collection and so on, is written. And using the CXSFIT software to process the CXRS experimental data to obtain the temporal and spatial distribution information of the ion temperature and the rotation speed in the EAST discharge process. In view of the important issue of the plasma rotation of the radio frequency wave driven plasma, the experimental study on the low clutter driven plasma rotation on the EAST is carried out. It is found that the low clutter drive in the current EAST operating range is in isolation. The rotation of the subbody changes in the direction of the current and has nothing to do with the rotation direction of the initial plasma. The response of the plasma rotation to the low clutter is the same as the response of the low clutter to the increase of the electron temperature and the increase of the internal energy. At the same time, it is found that the time of the rotation speed rising is slower than the low clutter after the low clutter is injected. In order to study the effect of different parameters on the rotation of low clutter driven by different parameters, the comparison experiment under different discharge conditions is carried out. The experimental results show that the driving effect of 4.6 GHz low clutter relative to 2.45 GHz low clutter is better than the electron temperature heating and electricity. The change of the rotational speed of the low clutter driven by the low clutter is proportional to the low clutter power, and the relationship between the plasma current and the plasma density is negatively correlated. In addition, the profile of the rotational velocity profile of the plasma after the low clutter injection is carefully analyzed. The rotation velocity is found after the low clutter injection plasma is injected. The variation of the whole profile is not synchronized, but is first changed in the low clutter power deposition region, and then transferred to the full section of the plasma. In the study of the low clutter injection under a NBI background plasma, there are two stages in the change of the rotational velocity after the low clutter injection plasma: in the low clutter injection. In 100ms, the velocity of rotation always changes to the direction of the reverse current at the low clutter power deposition region. Then with the continuous continuous injection of the low clutter at the same position, the rotation speed begins to change to the same current direction and then changes to the whole section. Finally, the observed experimental phenomena are qualitatively given. A simple physical model of low clutter driven plasma rotation: after low clutter injection plasma, the momentum of low clutter itself is transferred to electrons rapidly through Landau damping, and then passes through the collisions between electrons and ions to ions. This is a fast process and drives plasma in a short time after low clutter injection. The body turns to the reverse current direction. After the low clutter injection is injected into the plasma, a local radial electric field will be produced at its deposition position, thus forming the electromagnetic force produced by the radial flow and the polar magnetic field, which slowly produces a driving force in the direction of the same current in the ring direction, and gradually increases with the continuous injection of the low clutter until the radial charge is flat. When the force becomes larger and more than the force produced by the low mixed wave momentum, the effect of the cyclic force synthesis changes to the change of the rotating direction of the plasma and the direction of the current. The above two forces are all produced near the low clutter deposition position, and the local changes are passed through the momentum transport (diffusion term and pinch) to the whole separation. The sub body profile enables the plasma rotation to reach a new equilibrium in the circumferential direction.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TL631.24

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