Aerodynamic levitation

Aerodynamic levitation Aerodynamic force of a vertical gas stream A few nanolitres to 100 pi Depending on design of the device Almost any type. Difficulties may arise with liquids of low viscosity and/or surface tension Atmospheric chemistry experiments 112... 

The calibration procedure, then, is to measure voltage K for a given volumetric flow rate and calculate from the measured radius and knowledge of the gas viscosity. Note that when the flow rate is set such that no dc voltage is required to levitate the particle—that is, when the aerodynamic drag balances the weight—Eq. (33) can be used to determine the aerodynamic size, provided that the density is known. 

J. P. Coutures, J. C. Rifflet, D. Billard, and P. Coutures, Contactless treatments of liquids in a large temperature range by an aerodynamic levitation device and laser heating, in 6th Euro pean Symposium on Materials Science under Microgravity Conditions Vol. ESA SP 256,1987, pp. 427-430. 

T. Farmer, Structural Studies of Liquids and Glasses Using Aerodynamic Levitation, Springer Theses, DOI 10.1007/978-3-319-06575-5 l,... 

Alongside work relating directly to the application of aerodynamic levitation is the consideration of the possibility of combining in situ aerodynamic levitation and anomalous neutron scattering (ANS) [48]. The feasibility of this combination is initially tested purely with the application of ANS to the structure of a liquid semiconductor, indium selenide. 

As weU as investigating liquid InSe, determining the experimental challenges of an ANS experiment on a sample in a container wiU give some indication of the viability of an ANS aerodynamic levitation experiment. 

Chapter 3 will explain the four main experimental techniques used in this thesis neutron diffraction. X-ray absorption spectroscopy (XAS), and computer simulations for structural studies, and aerodynamic levitation and laser heating for sample preparation. 

Aral Y, Aoyama T, Yoda S (2004) Spherical sapphire single-crystal synthesis by aerodynamic levitation with high growth rate. Rev Sci Instrum 75(7) 2262... 

Nordine PC, Atkins RM (1982) Aerodynamic levitation of laser-heated solids in gas jets. Rev Sci Instrum 53(9) 1456... 

Skinner LB, Barnes AC, Crichton W (2006) Novel behaviour and structure of new glasses of the type Ba-Al-0 and Ba-Al-Ti-0 produced by aerodynamic levitation and laser heating. J Phys Condens Matter 18(32) L407-L414... 

Fig. 3.1 A schematic of the aerodynamic levitator setup used for this work. The laser and pyrometer are not incident on the same part of the sample...

A limitation of aerodynamic levitation is an incompatibility with very low density samples (<2 g/cm ) [14]. Along with this are the drawbacks of laser heating, which is not suitable for melting some samples. This can occur for a number of reasons due to a combination of very high and high reflectivity when the thermal conductivity is sufficiently low that the sample is ablated (such as for sulphide glasses) or when the sample does not absorb at 10.6 xm (such as for ZnSe glass). 

For samples where the mass loss during heating is minimal, it is possible to achieve stable levitation for periods in excess of 24 h. This allows the possibility of in situ measurements of various different liquid properties, such as electrical conductivity [42], density [52], and stractural measurements [16, 27, 32]. In the case of diffraction this requires an aerodynamic levitator setup on either a neutron or X-ray diffraction beamline, such as on D4c [32] at the ILL or D2AM [27] at the ESRF. 

The aerodynamic levitator used for the work in this thesis was purchased from Containerless Research, Inc., Evanston, IL, USA. 

However in the case of aerodynamic levitation the samples are spherical, for which the attenuation correction, Aj, follows intuitively from the derivation of Paalman and Pings [36] ... 

Skinner L, Barnes AC (2006) An oscillating coil system for contactless electrical conductivity measurements of aerodynamically levitated melts. Rev Sci lustrum 77(12) 123904... 

The sample stability in row A is that reported by Greaves et al. [5], although this is significantly lower than those reported for aerodynamic levitation [2] and combined aerodynamic and electrostatic [9] levitation shown in row B. Row C is an intermediate sample stabdity which stiU causes a significant error in the transmission... 

Arai Y, Paradis P-F, Aoyama T, Ishikawa T (2003) An aerodynamic levitation system for drop tube and quenching experiments. Rev Sci Instrum 74(2) 1057... 

Neutron diffraction was carried out on the samples in the liquid state using in situ aerodynamic levitation on the D4c diffractometer at the ILL [9]. The essential diffractometer setup is described in Table 6.2. The density was estimated by extrapolating between the liquid iron [35] and liquid nickel [2] densities of 7.1 and... 

Fig. 6.2 The bell jar setup used during aerodynamic levitation on D4c. The beam profile (shown in yellow) has been simplified so that the umbra and penumbra are not shown...

Further to this is the consideration of the applicability of ANS to aerodynamic levitation mentioned in Chap. 1, which will be considered in Sect. 7.4. 

Structural Studies of Liquids and Glasses Using Aerodynamic Levitation ... 

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