The motion of helium crystals has been experimentally studied when the crystals fall in the superfluid liquid owing to gravity at temperatures above the roughening transitions where the whole crystal surface is in the atomically rough state. The rate of crystal fall at T = 1.25 K is higher than at T = 1.54 K. This is proof of the essential role of the normal component of superfluid helium in the deceleration of crystal motion. The pressure measurements in the container have shown the effect of surface kinetics on the motions of the crystal and its size. The fall of crystals with the low surface mobility at T = 1.54 K does not change the pressure significantly. The high surface mobility at T = 1.25 K results in decreasing the pressure in the container in the course of the fall of a crystal. The pressure drop exceeds the difference in the hydrostatic pressure between the initial and final positions of the crystal. After the stop, the pressure in the container relaxes to the difference mentioned above. This fact demonstrates an additional growth of the crystal in the flow of a superfluid liquid.

中文翻译：

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$$^4$$He 量子晶体在超流体液体中的动力学

当晶体在高于粗糙化转变的温度下由于重力而落入超流体液体中时，氦晶体的运动已被实验研究，其中整个晶体表面处于原子粗糙状态。T = 1.25 K 时的晶体下降速率高于 T = 1.54 K。这证明了超流氦的法向成分在晶体运动减速中的重要作用。容器中的压力测量显示了表面动力学对晶体运动及其尺寸的影响。在 T = 1.54 K 时具有低表面迁移率的晶体的下降不会显着改变压力。T = 1.25 K 时的高表面迁移率导致在晶体下落过程中容器中的压力降低。压降超过了晶体初始位置和最终位置之间的静水压力差。停止后，容器内的压力松弛至上述差值。这一事实证明了晶体在超流体流动中的额外生长。