冷冻靶的环境热辐射屏蔽技术研究

通过建立三维柱腔冷冻靶计算模型，研究了外界环境辐射对间接驱动冷冻靶靶丸及燃料冰层温度场的影响。考虑柱腔内部激光入射孔（LEH）膜透光率对柱腔内靶丸和冰层温度场分布的影响，利用COMSOL软件对柱腔冷冻靶温度场进行了数值模拟计算。研究结果表明：受外界辐射影响，靶丸表面温度场呈两极热、赤道冷分布；LEH膜透光率越大，靶丸外表面温差和冰层内表面温差越大。当LEH膜透光率小于1%时，冰层内表面最大温差低于0.1 mK，可满足冰层均化和保持的要求。实验中，通过在LEH膜上镀不同厚度的铝层调控其透光率，并选择LEH膜镀铝层厚度为35 nm的冷冻靶开展了氘氘冷冻均化实验。结果表明：当LEH膜上的镀铝层厚度为35 nm时，冰层的保持能力得到大幅提升。从X射线相衬图像可知，冰层的厚度均匀性约为80.2%，粗糙度约为1.65 μm，平均厚度约为50.5 μm。

Environmental Thermal Radiation Shielding Technology of Cryogenic Target

In this work, in order to further optimize the external environment radiation shielding technology of the cryogenic target, through the combination of numerical simulation and experiment, the effect of external environmental radiation on the temperature field distribution of the target and ice layer was studied. Considering the influence of the transmittance of the laser entrance hole (LEH) film on the temperature field distribution of the target and ice layer in the column cavity, the temperature field of a target type in the column cavity was simulated and calculated using COMSOL software. The research results show that the temperature field distribution on the surface of the target is bipolar hot and equatorially cold under the influence of external radiation. Within a certain range, the greater the transmittance of the LEH film, the greater the temperature difference between the outer surface of the target and the inner surface of the ice. When the cylindrical cavity is irradiated with 300 K and the LEH film is pure PI film, the maximum temperature difference on the outer surface of the target pellet is about 20 mK. When the transmittance of the LEH film is less than 1%, the maximum temperature difference of the inner surface of the ice layer is less than 0.1 mK, which can meet the requirements of the ice layering and maintenance. In the experiment, by plating aluminum layers with different thicknesses on the LEH films, the transmittance of the LEH film was adjusted. When the cylindrical cavity was irradiated with 300 K and the LEH film is pure PI film, the deuterium vapor pressure at high temperature is higher than that at low temperature. Therefore, the high pressure deuterium vapor migrates to the low pressure deuterium vapor area, which is finally reflected in the macroscopic view that, within 300 s, the temperature difference drives the ice layer to migrate from two poles to the equator. When the thickness of the aluminum layer on the LEH film was 35 nm, the deuterium layering experiment was carried out. The experimental results show that when the thickness of the aluminum coating on the LEH film is 35 nm, the retention ability of ice layer is greatly improved. The ice layer can be maintained for more than 50 minutes without significant changes. From the X-ray phase contrast pictures, the thickness uniformity of the ice layer is about 80.2%, the roughness is about 1.65 μm, and the average thickness is about 50.5 μm. Through this work, an important foundation is laid for the preparation of high-quality fuel ice layer for the cylindrical cryogenic target and the improvement of physical experiment performance of the inertial confinement fusion.