Effects of some parameters on the divertor plasma sheath characteristics and fuel retention in castellated tungsten tile gaps

Castellation of plasma facing components is foreseen as the best solution for ensuring the lifetime of future fusion devices. However, the gaps between the resulting surface elements can increase fuel retention and complicate fuel removal issues. To know how the fuel is retained inside the gaps, the plasma sheath around the gaps needs to be understood first. In this work, a kinetic model is used to study plasma characteristics around the divertor gaps with the focus on the H＋ penetration depth inside the poloidal gaps, and a rate-theory model is coupled to simulate the hydrogen retention inside the tungsten gaps. By varying the magnetic field strength and plasma temperature, we find that the H＋ cyclotron radius has a significant effect on the penetration depth. Besides, the increase of magnetic field inclination angle can also increase the penetration depth. It is found in this work that parameters as well as the penetration depth strongly affect fuel retention in tungsten gaps.     

EAST中装置中靶板材料对边缘等离子体的影响

靶板的材料是当前聚变研究中的重要问题之一,偏滤器靶板材料的选择对偏滤器靶板寿命、杂质控制和等离子体参数的提升都有重要意义。在高参数等离子体条件下,会有巨大的粒子流和热流通过刮削层到达偏滤器靶板,进而引起靶板的溅射和侵蚀。因此不同材料的靶板在等离子体轰击下对边缘区域等离子体参数的影响也会不同。在本工作中,我们使用三维边缘输运程序EMC3-EIRENE研究了锂、硼、碳、钨四种不同的靶板材料下的电子密度、电子温度以及中性粒子密度的分布。结果发现钨靶板的下游电子密度明显低于其余3种靶板材料,而钨靶板的下游电子温度则较高。中平面附近的电子温度和密度分布也观察到了相似的规律。     

快速真空紫外光谱诊断在EAST实验的初步应用

为了在EAST装置上开展高参数放电条件下边界杂质辐射的实验研究,发展了真空紫外(VUV)光谱诊断系统。该系统采用了焦距为200mm的Seya-Namioka型VUV光谱仪,并配备了600g·mm^-1凹面全息光栅,所能观测的波长范围为50~700nm,覆盖真空紫外、近紫外和可见光波段。系统在垂直方向的观测范围为Z=-350~350mm。利用该系统开展了EAST边界杂质谱线的实验研究。通过分析CⅣ(154.8nm)杂质和FeⅡ(235nm)的谱线强度的时间演化行为,验证了该系统谱线强度测量的准确性与可靠性。通过分析CⅠ(365.2nm)杂质辐射强度在加热功率调制下的时间演化行为,验证了该系统研究较短时间尺度的杂质辐射行为的可行性。