DETECTION OF SINGLE QUANTA OF CIRCULATION IN LIQUID HELIUM .2.
DETECTION OF SINGLE QUANTA OF CIRCULATION IN LIQUID HELIUM .2.
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DOI：
10.1098/rspa.1961.0029
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发表时间：
1961-01-01
影响因子：
--
通讯作者：
VINEN, WF
中科院分区：
文献类型：
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作者：
VINEN, WF
本文描述了一种探测液氦Ⅱ中绕细线的单量子超流循环的装置。金属丝沿着装有氦气的圆柱形容器的中心向下伸展，通过绕金属丝的轴线旋转整个装置并从λ点上方冷却，可以建立循环。金属丝可作横向振动，然后由振动平面的进动率可求得绕金属丝的循环。该技术被证明是足够的灵敏度为测量的订单h/m的精度约为3%。该方法在其目前的形式中仅测量沿导线长度沿着的环流的平均值，并且发现该平均值不是量化的。等于一个量子的分数的表观环流被归因于量子化的涡旋，它们只附着在金属丝长度的一小部分上，这种解释已经被证实，因为精确的h/m的表观环流比任何其他值都具有更大的稳定性。用这种方法，以h/m为单位的超流环流的量子化得到了实验验证。在这项工作的过程中所做的观察清楚地表明，超流环流（包括自由涡线）可以无限期地持续下去，即使当设备的旋转停止。也得到了绕金属丝的环流作为旋转角速度的函数的值，从这些值可以看出，金属丝周围的氦中的自由涡线的能量可能比迄今所假定的要小得多。
An apparatus is described for detecting single quanta of superfluid circulation round a fine wire in liquid helium II. The wire is stretched down the centre of a cylindrical vessel containing helium, and the circulation may be established by rotating the whole apparatus about the axis of the wire and cooling from above the λ-point. The wire can be set into transverse vibration, and the circulation round it can then be obtained from the rate of precession of the plane of vibration. The technique proves to be sufficiently sensitive for the measurement of circulations of orderh/mwith an accuracy of about 3%. The method in its present form measures only an average of the circulation along the length of the wire, and it is found that this average is not quantized. Apparent circulations equal to a fraction of a quantum are attributed to quantized vortices that are attached to only a fraction of the length of the wire, and this interpretation has been confirmed by showing that an apparent circulation of exactlyh/mhas much greater stability than any other value. In this way the quantization of superfluid circulation in units ofh/mhas been experimentally verified. Observations made in the course of this work show clearly that superfluid circulations (including free vortex lines) can persist indefinitely even when the rotation of the apparatus is stopped. Values have also been obtained for the circulation round the wire as a function of the angular velocity of rotation, and it is shown from these that the energy of a free vortex line in the helium surrounding the wire may perhaps be considerably smaller than has hitherto been supposed.