微充气管残留燃料冰对冷冻靶控温过程的影响分析

Influence of Residual Fuel Ice in Micro Gas Filling Tube on the Temperature Control of ICF Cryogenic Target

针对微充气管内残留燃料冰影响冷冻靶控温过程这一问题,建立了基于Boussinesq假设和离散坐标辐射模型的三维数学模型,分析了管内残留燃料冰长度对基准、辅助加热以及快速降温3种工况下靶丸表面温度均匀性以及稳定性的影响。结果表明:基准稳态工况下,靶丸表面最大温差随管内燃料冰长度增长先降低后升高,燃料冰末端与靶丸外表面齐平(长度为0.09 mm)时,最大温差最小,相比于无燃料冰降低31.5%;施加7500 W/m^(2)辅助热流的瞬态工况下,管内残留燃料冰长度不同时,靶丸表面最大温差随时间变化均表现为先增大后减小直至稳定不变,燃料冰长度较短(≤0.09 mm)时,靶丸表面均匀性恶化程度较轻;以6 K/min进行线性快速降温过程中,管内燃料冰长度为0.09 mm时,降温过程中稳定性最好,降温结束时均匀性最佳;当管内燃料冰长度为0.09 mm时,3种控温工况下靶丸表面温度均匀性及稳定性均较好,可达到较好的控温效果。

The fuel capsule of cryogenic ICF target is generally filled through a micro tube.In order to generate the required smooth and uniform low-temperature layers,the capsule needs to be cooled and heated repeatedly with a residue of fuel ice in the gas filling tube until the crystal seed is formed and grows to a single-crystal layer.Based on Boussinesq assumption and the discrete coordinate radiation model,a three-dimensional simulation model is established to investigate the influence of the gas filling tube residual ice on the temperature control of fuel capsule,in detail,the influence of the length of the gas filling tube residual ice on the capsule temperature uniformity and stability in the standard steady-state,shimming heating and rapid cooling processes.Results show that in the standard steady-state process,the maximum temperature difference on the capsule surface lowers and then rises with the increase of the gas filling tube residual ice length,and when the ice end is flush to the outer surface of the capsule(optimal ice length of 0.09 mm),the maximum temperature difference reaches the lowest level,lowered by 31.5%compared with the none ice residue condition.During the transient process of shimming heating,the maximum temperature difference on the capsule surface rises and then lowers with time,finally staying stable,and the capsule temperature uniformity is less deteriorated when the ice length in the gas filling tube is shorter than or equal to 0.09 mm.Moreover,the capsule with an ice length of 0.09 mm maintains the best temperature stability(during cooling)and uniformity(at the end of cooling)when it is linearly cooled at a rate of 6 K/min,thus ensuring relatively good temperature control performance.