QUANTIZED VORTEX RINGS IN SUPERFLUID HELIUM
QUANTIZED VORTEX RINGS IN SUPERFLUID HELIUM
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DOI：
10.1103/physrev.136.a1194
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发表时间：
1964-01-01
期刊：
影响因子：
--
通讯作者：
REIF, F
中科院分区：
文献类型：
--
作者：
RAYFIELD, GW;REIF, F
有证据表明，在低温下，超流氦中的带电粒子可以被加速，在液体中形成自由移动的带电荷涡环。通过测量涡旋环的能量和速度，可以确定这些涡旋环的环流；它等于一个量子h m， h是普朗克常数，m是氦原子的质量。漩涡的核心半径约为1 Å。这种涡旋环在外力作用下运动的动力学性质可以用连接其能量E和动量p的色散关系E∝p12来描述；它也可以用流体动力马格纳斯力来详细地理解。实验证明了这种动力学分析的基本有效性。涡旋环可以与液体中的各种准粒子相互作用，即与质子、声子和He 3杂质相互作用。这些准粒子被旋涡环散射，可以通过设计实验来研究旋涡环在液体中运动时能量损失率的温度依赖性。用这种方法可以测量各种准粒子通过涡线散射时的有效动量传递截面。由此推算出的质子散射截面为9.5 Å，氦原子散射截面为18.3 Å。实验只得到少量关于声子散射的信息，但与理论基础上期望的声子散射截面的大小并不矛盾。
Evidence is presented to show that charged particles in superfluid helium at low temperatures can be accelerated to create freely moving charge-carrying vortex rings in the liquid. The circulation of these vortex rings can be determined by measuring their energy and velocity; it is found to be equal to one quantum h m, where h is Planck's constant and m is the mass of a helium atom. The core radius of the vortex is approximately 1 Å. The dynamical properties of such a vortex ring moving under the influence of external forces can be described by a dispersion relation E∝ p 1 2 connecting its energy E and momentum p; it can also be understood in detail in terms of the hydrodynamic Magnus force. Experiments are described which verify the essential validity of this dynamical analysis. Vortex rings can interact with various quasiparticles in the liquid, ie, with rotons, phonons, and He 3 impurities. The scattering of these quasiparticles by vortex rings can be investigated by experiments designed to study the temperature dependence of the rate of energy loss of such rings moving through the liquid. In this way it is possible to measure the effective momentum-transfer cross sections for scattering of the various quasiparticles by vortex lines. The cross section thus deduced is 9.5 Å for scattering of rotons and 18.3 Å for scattering of He 3 atoms. The experiments yield only scant information about scattering of phonons, but are not inconsistent with the magnitude of the phonon scattering cross section expected on theoretical grounds.