【作者】 丁永华；

【导师】 潘垣； 万宝年；

【作者基本信息】 华中科技大学 ， 脉冲功率与等离子体， 2005， 硕士

【摘要】 软X 射线能谱(PHA)是测量电子温度的常规手段,经过几年的发展在HT-7 上安装紧凑的较高空间分辨率的软X 射线PHA 诊断系统,为等离子体放电,尤其是为低杂波电流驱动(LHCD)实验提供比较精细可靠的电子温度的剖面的数据,为研究等离子体的输运和波与等离子体相互作用等物理机制提供了一定的条件。本文首先介绍了利用软X 射线能谱测电子温度的原理和方法以及HT-7 上软X 射线PHA 诊断系统。然后从理论上分析了软X 射线能谱测电子温度的优缺点,特别是对由弦积分和探头的分辨率带来的误差进行了系统的分析。数值模拟显示,温度分布越峰化,密度分布越平坦,因为弦积分造成的误差就越大。拟合能量的值越大,弦积分造成的误差就越小,但是在实际实验中,受金属杂质线辐射和高能快电子的影响,在HT-7 上选取的能量拟合值大概在温度的2.5～4 倍之间。在HT-7 的温度和密度的参数下,误差大概在10%～20%。探头的能量分辩率越低,计算的温度就会越高,但是探头的能量分辩率对电子温度的计算造成的相对误差不大。特别是温度较高时对能量分辩率的依赖就更小了,在HT-7 现有的条件下这种误差会小于2%。最后以软X射线PHA所测的电子温度的基础上对HT-7LHCD实验下的电子加热展开了研究。系统地分析了低杂波电流驱动下等离子体电子温度和电子加热效率与低杂波功率,等离子体密度,和等离子体电流等放电参数之间地关系。结果显示随着低杂波的功率和等离子体电子密度增加时,电子温度剖面会变峰化。同时发现在低杂波电流驱动下等离子体电子碰撞加热对等离子体电子密度很敏感。等离子体密度越大,电子之间得碰撞效果就越好,电子的加热效率也就越高。更多还原

【Abstract】 As a useful and conventional diagnostic to measure the electron temperature, the soft X-ray pulse height analysis (PHA) system has been installed on many tokamaks. The electron temperature profile with high spatial resolution and appropriate time resolution have been obtained from the soft X-ray PHA in HT-7. It is an important tool to study plasma transport and plasma-wave interactions in LHCD plasma. In this thesis, the theory of measuring electron temperature with the soft X-ray PHA and the system in HT-7 was introduced. The soft X-ray PHA diagnostic measures the line-integrated emission, which the spectrum used to derive the electron temperature is not a local emission. Therefore, the measured spectrum deriving the electron temperature brings some uncertainties. It is discussed in this thesis. It can be obtain that the error with the line-integrated emission is about 10%~20% SX_PHA in HT-7. The error is reversed to density profile factor and fitting energy region e, proportional to temperature profile factor. It is necessary to correct the measured value in discharges with plat density profile, peaked temperature profile. Electron heating via Lower hybrid current drive (LHCD) has been investigated in the HT-7 Superconducting tokamak. Experiments show that the central electron temperature (Te0), the volume averaged electron temperature (<Te>), and the peaking factor of the electron temperature (QTe=Te0/<Te>) increase with the LHW power. Simultaneous the electron heating efficiency and the electron temperature as the function of the central line-averaged electron density (ne) and the plasma current (Ip) were investigated. The experiment results are in good agreement with the class collision theory.更多还原