Ripening of Splashed 4He Crystals by Acoustic Waves with and without Gravity
Ripening of Splashed 4He Crystals by Acoustic Waves with and without Gravity
复制标题
在有重力和无重力的情况下通过声波使飞溅的 4He 晶体成熟
DOI：
10.1088/1367-2630/14/12/123023
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发表时间：
2012
影响因子：
3.3
通讯作者：
Y Okuda
中科院分区：
文献类型：
--
作者：
T. Takahashi;H. Ohuchi;R. Nomura;Y Okuda
通过开发与小型喷气式飞机抛物线飞行兼容的制冷机，在 0.6 K 的零重力条件下获得了超流体中的 4 He 晶体。我们报告了这些晶体在超流体中被声波溅射后的奥斯特瓦尔德成熟。奥斯特瓦尔德熟化是较小晶体熔化和较大晶体生长以最小化总表面能的过程。在地面重力作用下，这种成熟并不明显，因为它在毛细管长度约为 1 毫米时停止生长；较低位置的晶体生长以最小化重力能。然而，在没有重力的情况下，观察到的奥斯特瓦尔德熟化可达 10 毫米左右，由于毛细管长度无限长，其长度比 1 毫米大得多，表现出仅由表面能驱动的晶体形状的新颖演变。
By developing a refrigerator compatible with the parabolic flight of a small jet plane, 4 He crystals in a superfluid were obtained in zero-gravity conditions at 0.6 K. We report Ostwald ripening of these crystals in the superfluid after being splashed by acoustic waves. Ostwald ripening is a process in which smaller crystals melt and larger ones grow to minimize the overall surface energy. Under gravity on the ground, this ripening was not apparent because it stopped growing at a capillary length of about 1 mm; crystals at lower positions grew to minimize the gravitational energy. Without gravity, however, Ostwald ripening was observed up to the order of 10 mm, a much greater length than the 1 mm due to the infinitely long capillary length, exhibiting a novel evolution of the crystal shape driven solely by the surface energy.