Realization of mechanical rotation in superfluid helium

Гордон, Е. Б.; Kulish, Mariano; Karabulin, A. V.; Matyushenko, V. I.; Dyatlova, E. V.; Gordienko, Alexey Sergeevich; Stepanov, M. E.

doi:10.1063/1.5004447

Cited by 4 publications

(8 citation statements)

References 30 publications

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“…The presence in nanoweb of spherical clusters being similar to those formed in common liquids was associated with exceedingly high density of a metal introduced into liquid helium [19]. The hot clusters then have no time for cooling down between their successive mutual collisions and they could grow larger than the critical size, determined by the form ula (5) of [23].…”

Section: Laser Physics Lettersmentioning

confidence: 97%

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The nanowires growth by laser ablation of metals inside rotating superfluid helium

et al. 2018

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Under laser ablation of metals into superfluid helium (He II), in contrast to the widely used laser ablation in all other liquids, the main product of condensation is thin nanowires. In this case, however, the faults as the inclusions in the wire core of the spherical nanoparticles, similar to those which are condensation products in ordinary liquids, take place. It has been shown experimentally that the rotation of a reactor with He II, together with the replacement of laser target above the He II surface dramatically improves the structure of nanowires such produced and increases their length. Such behavior is explained both by the regularization of the array of vortices in the rotating He II and by the reducing the local density of the metal in liquid helium when the laser target is located in a gas.

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Section: Laser Physics Lettersmentioning

confidence: 97%

“…However, the nanowebs produced by laser ablation of a metal in He II included an appreciable amount of nanospheres with diameters much larger than the nanowire diameter [19]. For the nanoweb application as a catalyst this was not significant disadvantage.…”

Section: Laser Physics Lettersmentioning

confidence: 99%

The nanowires growth by laser ablation of metals inside rotating superfluid helium

et al. 2018

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“…Understanding of this shortcoming has allowed us to create a new design, where spherical inclusions in nanowires are absent, and the length of individual nanowires in a nanoweb is significantly higher than in the original method. 21 That will be especially important in the studies of different size effects, for example in superconductivity 22 or in quantum phase shift. 23 Finally the main conclusion of this study can be represented graphically in Figure 6.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Besides the consumption of the ablated metal for inclusions production decreases the yield of nanowires. Understanding of this shortcoming has allowed us to create a new design, where spherical inclusions in nanowires are absent, and the length of individual nanowires in a nanoweb is significantly higher than in the original method . That will be especially important in the studies of different size effects, for example in superconductivity or in quantum phase shift …”

Section: Discussionmentioning

confidence: 99%

Coagulation of Metals in Superfluid and Normal Liquid Helium

et al. 2017

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The thermal emission study in this work has shown that coagulation of metals in liquid helium is accompanied by enormous local overheating of several thousand degrees. Direct experiments demonstrated, for the first time, that condensation of metals in superfluid helium occurs via the specific mechanism which is substantially faster than that in normal liquid helium. It has been stated that coagulation of metals in superfluid helium indeed occurs in two stages, a "hot" one of nanoparticles coalescence with the formation of molten nanospheres and the subsequent stage of their sticking together into nanowires. It turned out that if a laser ablation of metal targets immersed in superfluid helium was used for introducing a metal into liquid, the formation of nanowires occurs at distances of only about 1 mm from the laser focus. This leads to the presence of a considerable number of spherical inclusions in nanowires grown in such a way.

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“…One unique feature of this setup is the ability to rotate our beaker at cryogenic temperatures. The possibility of rotating a beaker containing He II was demonstrated in previous work [18,19]. In our setup, rotation of the beaker is accomplished by mounting the quartz beaker to the output shaft of a stepper motor (see Fig.…”

Section: Methodsmentioning

confidence: 99%

Rotationally induced luminescence of nanoclusters immersed in superfluid helium

McColgan

Sheludiakov

Rentzepis

et al. 2019

Low Temperature Physics

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We studied the influence of rotation speed of a beaker containing superfluid helium (He II) on the intensity of luminescence of collections of nanoclusters immersed in He II. We observed an increase in the α-group emission of nitrogen atoms ( 2 D→ 4 S transition) in nanoclusters which correlated with the increasing of rotational speed of the beaker. Increasing luminescence was also observed by increasing the concentration of molecular nitrogen in the nitrogen-helium gas mixtures used for the formation of the molecular nitrogen nanoclusters. We suggest that this effect is caused by the change of the density of quantum vortices in He II initiated by variation of rotational speed of the beaker. When the density of the vortices is increased, the probability for the nanoclusters to become trapped in the vortex cores is also increased. The collisions in the vortex cores of trapped nanoclusters with nitrogen atoms stabilized mostly on the surfaces of the nanoclusters initiate the recombination of nitrogen atoms resulting in luminescence.

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Realization of mechanical rotation in superfluid helium

Cited by 4 publications

References 30 publications

The nanowires growth by laser ablation of metals inside rotating superfluid helium

The nanowires growth by laser ablation of metals inside rotating superfluid helium

Coagulation of Metals in Superfluid and Normal Liquid Helium

Rotationally induced luminescence of nanoclusters immersed in superfluid helium

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