Showing papers on "Critical radius published in 1978"
TL;DR: Theoretically and experimentally, the homogeneous nucleation of bubbles in liquid gas solutions is considered in this article, where the stability of a homogeneous liquid phase is specified by the critical radius, Rc.
Abstract: The homogeneous nucleation of bubbles in liquid‐gas solutions is considered theoretically and experimentally. The stability of a homogenous liquid phase is shown to be specified by the critical radius, Rc. If Rc is negative or infinite, then the liquid is stable; however, if Rc is positive then the liquid is metastable. The prediction of the pressure at which nucleation occurs follows from nucleation theory. At a given temperature, the presence of a dissolved gas is shown to significantly raise the pressure at which nucleation occurs. These predictions were experimentally tested for ethyl ether droplets containing dissolved nitrogen using an isothermal decompression technique. Results are presented for a range of gas concentrations including values for which it is predicted that nucleation should occur at pressures greater than the vapor pressure of the pure liquid. Good agreement between theoretical and measured nucleation pressures was obtained.
38 citations
TL;DR: In this paper, the authors explore two types of instability which may develop when a highly conducting gas rotates rapidly in the presence of a radial gravitational force and an azimuthal magnetic field.
Abstract: We explore two types of instability which may develop when a highly conducting gas rotates rapidly in the presence of a radial gravitational force and an azimuthal magnetic field. Beyond a critical radius (equal to twice the isothermal scale height) a decrease of magnetic flux (per unit mass) outwards leads to the appearance of eastward-propagating waves by the mechanism of ‘magnetic buoyancy’. Within the critical radius an increase of magnetic flux outwards leads to westward-propagating waves by a totally different mechanism. Provided that the effects of Ohmic dissipation are not too large, either instability may set in for quite modest magnetic flux gradients, even when the magnetic energy of the system is very much smaller than the rotational energy.
35 citations
TL;DR: In this article, the authors derived the critical radius at which the change from interface-to diffusion controlled kinetics takes place and derived an approximate form of the growth equation for particle growth in PE16.
29 citations
TL;DR: In this article, it was shown that a vanishing critical size does not exist for a body finite in all dimensions, as well as for an infinite cylinder, unless the second moment of Dirac's chord distribution is finite.
Abstract: The one-speed neutron criticality problem is investigated in general geometry for a fission and scattering kernel with an extreme forward bias. It is shown that a vanishing critical size does not exist for a body finite in all dimensions, as well as for an infinite cylinder. This is in contrast to a previous result reported in plane geometry. In general, a vanishing critical size will not exist if the second moment of Dirac's chord distribution is finite. This leads to the conclusion that a body must be infinite in two dimensions (e.g., a slab) to exhibit a vanishing critical thickness. Numerical results for spheres indicate that the critical radius varies monotonically with anisotropy, whereas infinite cylinders exhibit a critical radius varying non-monotonically with anisotropy. 4 references.
21 citations
TL;DR: Several versions of a model in which inhibition is produced by depletion of a substance, needed both for growth and for nucleation, below a critical concentration for the latter are discussed, probably analogous to the critical micelle concentration in detergent solutions.
13 citations
8 citations
TL;DR: In this paper, the viscosity for the motion and the free energy of the disclination of a circular homeotropic domain is analyzed. But the analysis is limited to the case where the radius R is smaller or larger than a critical radius Rc.
1 citations
TL;DR: In this article, three-group diffusion theory has been applied to a computation of the 231Pa mass required to sustain a fast-neutron chain reaction, and the method was tested by preliminary calculation of several 235U-238U systems and of a single 239Pu-240Pu system.
Abstract: Three-group diffusion theory has been applied to a computation of the 231Pa mass required to sustain a fast-neutron chain reaction. The method was tested by preliminary calculation of several 235U-238U systems and of a single 239Pu-240Pu system. The best agreement between predictions and measurements was found for high-enrichment 235U-238U systems. In the case of 231Pa, where many of the necessary data do not exist, use was made of the characteristics of 237Np as a substitute. The predicted critical radius for 231Pa is 22.67 ± 1.81 cm, and the corresponding critical mass is 750 ± 180 kg.
1 citations
TL;DR: In this article, the Coulomb interaction between ions often causes considerable changes in the observed efficiency of energy transfer, since the Debye radius of shielding can be compared with the critical radius for energy transfer (Forster's radius).
Abstract: In many cases energy transfer occurs between the ions 1–8 and therefore its efficiency depends not only on the diffusion of ions but on the Coulomb interaction. Diffusion causes ions to draw nearer. Consequently the rate of energy transfer increases because this rate decreases with increasing distance between the sensitizer (S) and the activator (A). The presence of the Coulomb interaction leads to the redistribution of ions A near the ion S. As a function of a sign of ionic charge the concentration of A near the ion S will be more or less in comparison with the random concentration of these ions in solution. Since the Debye radius of shielding can be compared with the critical radius of energy transfer (Forster's radius) the Coulomb interaction between ions often causes considerable changes in the observed efficiency of energy transfer.