Ice particles trapped by temperature gradients at mbar pressure

Kelling, T.; Wurm, Gerhard; Dürmann, C.

doi:10.1063/1.3658824

Cited by 8 publications

(14 citation statements)

References 15 publications

(20 reference statements)

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“…As already discussed by Krauss et al (2007), levitating particles (in their case dust particles) tend to rotate. The same has been observed for the levitating ice particles in the experiment by Kelling et al (2011). Therefore, we here use the above‐mentioned trapping technique to perform a detailed study of the rotation of levitating ice particles which are under the influence of photophoresis, thermophoresis and gravity.…”

Section: Introductionsupporting

confidence: 55%

“…Therefore, it would be favourable if free particles were observed and manipulated in laboratory experiments. Fortunately, a technique to do so was recently developed by Kelling, Wurm & Dürmann (2011). In their work, they show that micron‐sized water ice particles levitate under the Earth’s gravity, trapped in stable positions by photophoresis and thermophoresis.…”

Section: Introductionmentioning

confidence: 99%

“…In the first case, the temperature gradient exists across the particle (internal gradient), while the gaseous environment is at a constant temperature; in the latter case, the temperature gradient exists in the gaseous environment (external gradient). In the experiments by Kelling et al (2011), photophoretic lift is induced by the thermal radiation of a surface at 250 K.…”

Section: Introductionmentioning

confidence: 99%

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The implications of particle rotation on the effect of photophoresis

Eymeren¹,

Wurm²

2011

Monthly Notices of the Royal Astronomical Society

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In a laboratory experiment, water-ice aggregates are trapped in a vacuum chamber at a pressure of 2 mbar due to photophoresis and thermophoresis. The particles are located between a Peltier element at the bottom at 250 K and a reservoir of liquid nitrogen at the top at 77 K. Particle sizes vary between 20 micrometres and a few hundred micrometres. It is found that 95% of all the particles rotate about their vertical axis. A qualitative model is developed which explains why particles should mainly align to and rotate around the vertical. The results imply that rotation does not decrease the vertical strength of photophoretically driven motion in, e.g., protoplanetary discs.Comment: 4 pages, 4 figures, accepted for publication by MNRA

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Section: Introductionsupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The implications of particle rotation on the effect of photophoresis

Eymeren¹,

Wurm²

2011

Monthly Notices of the Royal Astronomical Society

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“…To prove this van Eymeren & Wurm (2012) carried out a detailed study of particle rotation. In their setup particles were levitated by means of thermophoresis and photophoresis (Kelling et al 2011). van Eymeren & Wurm (2012 found that at least more than 95% of all particles rotate around the vertical direction which coincides with the direction of illumination.…”

Section: Caveatsmentioning

confidence: 99%

Thermal and photophoretic properties of dust mantled chondrules and sorting in the solar nebula

Loesche

Wurm

2012

A&A

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Many chondrules are found to be surrounded by a fine grained rim. Supposedly, these rims were acquired from dust accreted to the chondrules in a protoplanetary disk. In numerical simulations we study the heat transfer in illuminated bare and dust mantled chondrules. The calculations consider the chondrule size, the dust mantle size, and the thermal conductivities of both components as parameters. We calculate the photophoretic force and compare the numerical results to analytical approximations. We give an expression to quantify the photophoretic force on a spherical particle in the free molecular regime to better than 2%. We describe the influence of a dust mantle on the photophoretic strength by an effective thermal conductivity of the core-mantle particle. The effective thermal conductivity significantly depends on the size ratio between mantle and chondrule but not on the absolute sizes. It also strongly depends on the thermal conductivity of the mantle with minor influence of the thermal conductivity of the chondrule. The size ratio between rim and chondrule in meteorites is found to vary systematically with overall size by other authors. Based on this, our calculations show that a photophoretic size sorting can occur for dust mantled chondrules in optically thin disks or at the evolving inner edge of the solar nebula.

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“…A technique to trap particles was recently developed by Kelling et al (2011). They show that micron-sized irregular-shaped water-ice particles levitate under the Earth's gravity due to photophoresis and thermophoresis.…”

Section: Introductionmentioning

confidence: 99%

Photophoresis on water-ice particles induced by thermal radiation in protoplanetary discs

Eymeren

Kelling

Wurm

et al. 2012

EAS Publications Series

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Abstract. It is widely believed that planets form in accretion discs by the growth of small dust and ice grains. To verify the scenarios of protoplanetary disc processes including the transport of material in vertical as well as in radial direction, it is crucial to understand the interaction of small dust and ice particles with their surroundings, i.e., with the gas, star light, and other ice and dust particles. In first laboratory experiments, we observe trapped irregular-shaped water-ice particles which levitate up to half an hour in a vacuum chamber at a pressure of about 2 mbar due to photophoresis and thermophoresis. While they are firmly levitating, they rotate preferentially about their vertical axis. The physics leading to the levitation is explained and the results of an analysis of the particle rotation are presented.

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Ice particles trapped by temperature gradients at mbar pressure

Cited by 8 publications

References 15 publications

The implications of particle rotation on the effect of photophoresis

The implications of particle rotation on the effect of photophoresis

Thermal and photophoretic properties of dust mantled chondrules and sorting in the solar nebula

Photophoresis on water-ice particles induced by thermal radiation in protoplanetary discs

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