靶丸位置对冷冻靶物理场的影响规律研究

Effects of Capsule Sag and Shift on the Thermal Environment of Cryogenic Target

针对冷冻靶丸装配工艺误差导致靶丸表面温度特性变化的问题,建立带充气管的三维模型,基于Boussinesq假设和离散坐标辐射模型,采用数值模拟方法,研究了靶丸及充气管在竖直和水平方向进行偏移时靶丸表面温度分布的变化,并分析比较了充气管、辅助加热及辐射对靶丸偏移敏感性的影响。结果表明:充气管对靶丸表面温度均匀性影响显著,相较于无充气管结构,具有单充气管和对侧双充气管的靶丸其外表面最大温差分别增大78.9%、76.7%;对于具有充气管结构的靶丸,存在使均匀性改善的最佳偏移工况;单充气管结构靶丸竖直向上适当偏移时,靶丸表面温度均匀性更好,最佳偏移距离为5μm,且单充气管结构在水平方向容许向左112μm的偏移;随着加热功率增大,竖直方向最佳偏移距离基本不变,但靶丸对水平方向装配工艺误差的容忍度增大;封口膜透射率越大,靶丸位置偏移越敏感,相同偏移距离下靶丸表面最大温差越大。

Three-dimensional numerical models are established to investigate the effects of capsule sag and shift on its thermal environment in cryogenic target with micro filling tubes.The simulation bases on Boussinesq hypothesis and a discrete ordinates radiation model.Variations of the target temperature and velocity distributions are studied when the capsule and its gas filling tube are offset in the vertical and horizontal directions and effects of gas filling tube,shimming heating and thermal radiation on the shift-and-sag sensitivity are analyzed.The results show that the gas filling tube has a significant effect on the surface temperature uniformity of the capsule,and the maximum temperature differences on the outer surface of the capsule with single filling tube and two opposite filling tubes increase by 78.9%and 76.7%respectively,compared with no filling tube configurations.For the case of the single filling tube,the capsule temperature uniformity can be improved when the target is offset vertically within a certain distance.Under given conditions,the optimal offset distance for maximum uniformity improvement is 5μm,while the horizontal offset of 112μm is allowed for the single gas filling tube configuration.With an increase in shimming heating power,the optimal offset distance in the vertical direction is almost unchanged,but the tolerance of the horizontal shift of the target increases.As to the thermal radiation,the larger the transmittance of sealing films is,the more sensitive the capsule temperature to the target offset is,along with the larger temperature difference.