Glass spheres produced by magnetic levitation method

Kitamura, Naoyuki; Makihara, Masaki; Sato, Takayuki; Hamai, M.; Mogi, Iwao; Awaji, Satoshi; Watanabe, Kazuo; Motokawa, M.

doi:10.1016/s0022-3093(01)00761-x

Cited by 20 publications

(19 citation statements)

References 12 publications

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“…with a size of 4 or 6 mm) in a furnace constituted by a CO 2 laser and a solenoid-type magnet was demonstrated [56,57]. The glass cube, placed in a platinum cage at the edge of the inner magnet, is made to levitate and there it is melted by the effect of the focused laser beam: a complete glass sphere was thus obtained after cooling.…”

Section: Melting Processesmentioning

confidence: 99%

Spherical whispering‐gallery‐mode microresonators

Chiasera

Dumeige

Féron

et al. 2010

Laser & Photonics Reviews

435

280

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International audienceWhispering-gallery modes (WGM) on a spherical surface were first described by Lord Rayleigh at the beginning of the last century, but only after the invention of laser did they start to have some scientific relevance and only during the last two decades there has been a substantial move towards real devices and practical applications. WGM resonators have peculiar properties, the most notable being the potential of having an ultrahigh quality factor Q, which makes them very appealing both as laser cavities and as extremely sensitive sensors. Among the different types of WGM resonators, the microspherical ones represent a very important category, due to their simplicity, easy fabrication, and very high quality. In this review we provide a description of their fundamental properties and we summarize recent works on their application as filters, sensors and lasers

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Section: Melting Processesmentioning

confidence: 99%

Spherical whispering‐gallery‐mode microresonators

Chiasera

Dumeige

Féron

et al. 2010

Laser & Photonics Reviews

435

280

View full text Add to dashboard Cite

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“…According to a Pascal rule, which explains the origin of diamagnetic susceptibility of solid insulators, a χ DIA value of a material is equivalent to the sum of the diamagnetic susceptibility assigned to individual orbital that compose the material [9]. It is hence expected that precise χ DIA data of individual particle provide information on the distortion of bulk crystal structure that is considered to increase with the reduction of crystal size [3].…”

Section: Resultsmentioning

confidence: 99%

“…It is believed that dynamic motions of weak magnetic (i.e. diamagnetic and paramagnetic) material require a strong field above B = 10T [1][2][3][4]. When a weak magnetic solid was released in μG space with negligible effect of gravity or viscous drag, two kinds of basic motions were expected to occur by low magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Magnetic ejection of submilimeter-sized diamagnetic grains observed in a chamber-type drop shaft

Hisayoshi

Uyeda

Kuwada

et al. 2011

J. Phys.: Conf. Ser.

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Abstract. Mass dependence of magnetically induced translation is examined for submilimetersized diamagnetic grain, which is floated in a diffused gas medium of 70 Pa by the use of microgravity μG condition. Here the grains are ejected from field-center of a pole-piece magnetic circuit by field-gradient force in a direction of decreasing field; maximum fieldintensity at initial point is about 0.6T. It was deduced from an energy conservation rule that magnetic potential of the grain at initial position was partially converted to kinetic energy during translation. Therefore, observed velocity was expected to be independent to mass of particle; this is because magnetic potential is proportional to mass of particle. In a given field distribution, the velocity was uniquely determined by intrinsic magnetic susceptibilityχ DIA of material. We report here that the magnetic ejection in μG condition is realized for sub-mm sized crystals of bismuth, graphite and magnesia. The χ DIA values obtained from the ejection agreed fairly well with the published values for the three materials. The mass-independent property of translation was examined by observing the translation of two bismuth grains with different sizes. A chamber-type drop shaft having a height of 1.5 m was introduced to produce the μG condition. By the use of this drop shaft, study of field-induced motion of a single diamagnetic particle becomes possible in an ordinary laboratory.

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“…The cooling rate for the levitated melt by using the gas -jet levitator was considerably higher than the radiative cooling rate (~ 30 K/s at the glass transition temperature) because of the heat conduction by gas -jet. Consequently, the gas -jet levitation method yields a higher cooling rate as compared to other levitation methods such as electromagnetic levitation (Kitamura et al, 2001) and electrostatic levitation (Mukherjee et al, 2006).…”

Section: Experimental Conditionsmentioning

confidence: 99%

Critical cooling rates for glass formation in levitated Mg2SiO4-MgSiO3 chondrule melts

Nagashima

MORIUCHI

Tsukamoto

et al. 2008

Journal of Mineralogical and Petrological Sciences

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Using a gas -jet levitator, Mg -silicate glasses containing forsterite (Mg 2 SiO 4 ) or enstatite (MgSiO 3 ) are obtained, -jet. It can transform the levitated droplets into crystals or glass during cooling. The critical cooling rate for glass formation (R c ) for levitated Mg -silicate melts ( 10 -1 -10 2 K/s) is considerably lower than that for non -levitated melts (>10 3 K/s) because of the inhibition of crystallization by the sample holder in the former. Furthermore, the crystallization temperature of the levitated Mg -silicate melts is very low (~ 900 °C). Chondrules in chondrites are assumed to have been formed from the melt droplets in such a levitation environment. Several researchers have concluded that R c for a chondrule melt held by a platinum wire is equal to the upper limit of the cooling rate for the chondrule melt, estimated to be ~ 1000 K/h. However, in a levitation environment, SiO 2 -rich melts do not crystallize at this cooling rate. We conclude that the previously proposed maximum cooling rate for chondrule melts has been greatly overestimated. We infer that spontaneous crystallization of a completely melted chondrule precur--tion of chondrule melts, it is necessary that the precursor of the chondrules should be partially melted or the completely melted precursor should be in contact with nebular dust.

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Glass spheres produced by magnetic levitation method

Cited by 20 publications

References 12 publications

Spherical whispering‐gallery‐mode microresonators

Spherical whispering‐gallery‐mode microresonators

Magnetic ejection of submilimeter-sized diamagnetic grains observed in a chamber-type drop shaft

Critical cooling rates for glass formation in levitated Mg2SiO4-MgSiO3 chondrule melts

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