scholarly journals Proximity force approximation and specular reflection: Application of the WKB limit of Mie scattering to the Casimir effect

2018 ◽  
Vol 97 (6) ◽  
Author(s):  
Benjamin Spreng ◽  
Michael Hartmann ◽  
Vinicius Henning ◽  
Paulo A. Maia Neto ◽  
Gert-Ludwig Ingold
Keyword(s):  
Casimir Effect ◽  
Specular Reflection ◽  
Mie Scattering ◽  
Proximity Force Approximation

Optical Modeling of Reflectivity Loss Caused by Dust Deposition on CSP Mirrors and Restoration of Energy Yield by Electrodynamic Dust Removal

2014 ◽  
Author(s):  
Jeremy Stark ◽  
Julius Yellowhair ◽  
John N. Hudelson ◽  
Mark Horenstein ◽  
Malay Mazumder
Keyword(s):  
Power Plants ◽  
Specular Reflection ◽  
Mie Scattering ◽  
Dust Removal ◽  
Dust Particles ◽  
Energy Yield ◽  
Dust Deposition ◽  
Optical Modeling ◽  
Specular Reflectivity ◽  
Semi Arid

For large scale CSP power plants, vast areas of land are needed in deserts and semi-arid climates where uninterrupted solar irradiance is most abundant. These power facilities use large arrays of mirrors to reflect and concentrate sunlight onto collectors, however, dust deposition on the optical surfaces causes obscuration of sunlight, resulting in large energy-yield losses in solar plants. This problem is compounded by the lack of natural clean water resources for conventional cleaning of solar mirrors, often with reflective surface areas of large installations exceeding a million square meters. To investigate the application of transparent electrodynamic screens (EDS) for efficient and cost effective dust removal from solar mirrors, both optical modeling and experimental verifications were performed. Prototype EDS-integrated mirrors were constructed by depositing a set of parallel transparent electrodes into the sun-facing surface of solar mirrors and coating electrodes with thin transparent dielectric film. Activation of the electrodes with a three-phase voltage creates an electrodynamic field that charges and repels dust electrostatically by Coulomb force and sweeps away particles by a traveling electrodynamic wave. We report here brief discussions on (1) rate of deposition and the properties of dust with respect to their size distribution and chemical composition in semi-arid areas of the southwest US and Mojave Desert and their adhesion to solar mirrors, (2) optical models of: (a) specular reflection losses caused by scattering and absorption by dust particles deposited on the surface based on Mie scattering theory, and (b) reflection loss by the integration of EDS on the mirror surface, computed by FRED ray-tracing model. The objective is to maintain specular reflectivity of 90% or higher by frequent removal of dust by EDS. Our studies show that the incorporation of transparent EDS would cause an initial loss of 3% but would be able to maintain specular reflectivity more than 90% to meet the industrial requirement for CSP plants. Specular reflection measurements taken inside a climate controlled environmental chamber show that EDS integration can restore specular reflectivity and would be able to prevent major degradation of the optical surface caused by the deposition of dust.

scholarly journals Role of diffraction in the Casimir effect beyond the proximity force approximation

2019 ◽  
Vol 36 (4) ◽  
pp. C77 ◽  
Author(s):  
Vinicius Henning ◽  
Benjamin Spreng ◽  
Michael Hartmann ◽  
Gert-Ludwig Ingold ◽  
Paulo A. Maia Neto
Keyword(s):  
Casimir Effect ◽  
Proximity Force Approximation

scholarly journals GEOMETRY-TEMPERATURE INTERPLAY IN THE CASIMIR EFFECT

2010 ◽  
Vol 25 (11) ◽  
pp. 2279-2292 ◽  
Author(s):  
H. GIES ◽  
A. WEBER
Keyword(s):  
Long Range ◽  
Casimir Effect ◽  
Fractional Power ◽  
Power Laws ◽  
Underlying Mechanism ◽  
Thermal Fluctuations ◽  
Parallel Plates ◽  
Small Surface ◽  
Temperature Dependences ◽  
Proximity Force Approximation

We discuss Casimir phenomena which are dominated by long-range fluctuations. A prime example is given by "geothermal" Casimir phenomena where thermal fluctuations in open Casimir geometries can induce significantly enhanced thermal corrections. We illustrate the underlying mechanism with the aid of the inclined-plates configuration, giving rise to enhanced power-law temperature dependences compared to the parallel-plates case. In limiting cases, we find numerical evidence even for fractional power laws induced by long-range fluctuations. We demonstrate that thermal energy densities for open geometries are typically distributed over length scales of 1/T. As an important consequence, approximation methods for thermal corrections based on local energy-density estimates such as the proximity-force approximation are expected to become unreliable even at small surface separations.

BEYOND PROXIMITY FORCE APPROXIMATION IN THE CASIMIR EFFECT

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1743-1747 ◽  
Author(s):  
M. BORDAG ◽  
V. NIKOLAEV
Keyword(s):  
Boundary Conditions ◽  
Casimir Force ◽  
Dirichlet Boundary ◽  
Casimir Effect ◽  
Neumann Boundary ◽  
Numerical Results ◽  
Dirichlet Boundary Conditions ◽  
Proximity Force Approximation ◽  
Interacting Surfaces ◽  
General Appearance

We compare the analytical and numerical results for the Casimir force for the configuration of a plane and a cylinder in front of a plane. While for Dirichlet boundary conditions on both, plane and sphere or cylinder, agreement is found, for Neumann boundary conditions on either the plane or one of the two, cylinder or sphere, disagreement is found. This holds, for a sphere, also for different boundary conditions on the interacting surfaces. From recent, new numerical results for the cylinder, a general appearance of logarithmic contributions beyond PFA can be predicted.

scholarly journals THE CASIMIR EFFECT IN THE SPHERE-PLANE GEOMETRY

2012 ◽  
Vol 14 ◽  
pp. 250-259 ◽  
Author(s):  
ANTOINE CANAGUIER-DURAND ◽  
ROMAIN GUÉROUT ◽  
PAULO A. MAIA NETO ◽  
ASTRID LAMBRECHT ◽  
SERGE REYNAUD
Keyword(s):  
Ambient Temperature ◽  
Casimir Force ◽  
Casimir Effect ◽  
Numerical Results ◽  
Plane Geometry ◽  
Finite Conductivity ◽  
Rich Variety ◽  
Proximity Force Approximation ◽  
Multipolar Expansion

We present calculations of the Casimir interaction between a sphere and a plane, using a multipolar expansion of the scattering formula. This configuration enables us to study the nontrivial dependence of the Casimir force on the geometry, and its correlations with the effects of imperfect reflection and temperature. The accuracy of the Proximity Force Approximation (PFA) is assessed, and is shown to be affected by imperfect reflexion. Our analytical and numerical results at ambient temperature show a rich variety of interplays between the effects of curvature, temperature, finite conductivity, and dissipation.

Macrostructure and microphysics of Saturn's E-ring

1984 ◽  
Vol 75 ◽  
pp. 607-613 ◽  
Author(s):  
Kevin D. Pang ◽  
Charles C. Voge ◽  
Jack W. Rhoads
Keyword(s):  
Size Distribution ◽  
Spherical Shape ◽  
Mie Scattering ◽  
Narrow Size Distribution ◽  
Electrostatic Levitation ◽  
Volcanic Origin ◽  
Micron Diameter

Abstract.All observed optical and infrared properties of Saturn's E-ring can be explained in terms of Mie scattering by a narrow size distribution of ice spheres of 2 - 2.5 micron diameter. The spherical shape of the ring particles and their narrow size distribution imply a molten (possibly volcanic) origin on Enceladus. The E-ring consists of many layers, possibly stratified by electrostatic levitation.

Forensic applications of IR infrared microscopic internal reflection spectroscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1528-1529
Author(s):  
Edward G. Bartick ◽  
John A. Reffner
Keyword(s):  
Specular Reflection ◽  
Forensic Analysis ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Standard Size ◽  
Ir Microscopy ◽  
Ir Analysis ◽  
Plastic Explosives ◽  
Internal Reflection Spectroscopy ◽  
Reflectance Measurements

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.

Sign in / Sign up

Export Citation Format

Share Document