Gain measurements of standard electromagnetic horns in the kappa and kappa alpha bands
Gain measurements of standard electromagnetic horn antennas for use in calibrating millimeter wave, parabolic radio telescopes
Wrixon, G.↗
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Generation of Kappa Distributions in Solar Wind at 1 au
We examine the generation of kappa distributions in the solar wind plasma near 1 au. Several mechanisms are mentioned in the literature, each characterized by a specific relationship between the solar wind plasma features, the interplanetary magnetic field (IMF), and the kappa index-the parameter that governs the kappa distributions. This relationship serves as a signature condition that helps the identification of the mechanism in the plasma. In general, a mechanism that generates kappa distributions involves a single or a series of stochastic or physical processes that induces local correlations among particles. We identify three fundamental solar wind plasma conditions that can generate kappa distributions, noted as (i) Debye shielding, (ii) frozen IMF, and (iii) temperature fluctuations, each one prevailing in different scales of solar wind plasma and magnetic field properties. Moreover, our findings show that the kappa distributions, and thus, their generating mechanisms, vary significantly with solar wind features: (i) the kappa index has different dependence on the solar wind speed for slow and fast modes, i.e., slow wind is characterized by a quasi-constant kappa index, K (is) approx. 4.3 +/- 0.7, while fast wind exhibits kappa indices that increase with bulk speed; (ii) the dispersion of magnetosonic waves is more effective for lower kappa indices (i.e., further from thermal equilibrium); and (iii) the kappa and polytropic indices are positively correlated, as it was anticipated by the theory.
Livadiotis, G.↗
Application of the kappa-omega Turbulence Model to Quasi-Three-Dimensional Turbomachinery Flows
Many computational fluid dynamics codes for turbomachinery use the Baldwin-Lomax (B-L) turbulence model. It is easy to implement in two dimensions and works well for predicting overall turbomachinery performance. However, it is awkward to implement in three dimensions, often has difficulty finding the length scale, has a crude transition model, and neglects freestream turbulence, surface roughness, and mass injection. The kappa-omega model developed by Wilcox is an appealing alternative for several reasons. First, it is the only two-equation model that can be integrated to the wall without requiring damping functions or the distance to the wall, and hence, should behave well numerically. Second, the effects of freestream turbulence, surface roughness, and mass injection are easily included in the model. Finally, transition can be simulated using the low Reynolds number version of the model. Menter applied the kappa-model to external flows and showed very good results for flows with adverse pressure gradients. Liu and Zheng described their implementation of the kappa-model in a cascade code that included an area change term to account for endwall convergence. They validated the model for a flat plate, and compared the B-L and kappa-models to measured surface pressures for a low-pressure turbine cascade. Since they did not use the low Reynolds number version of the model, their results showed problems resulting from early transition. In this Note the low Reynolds number kappa-model was incorporated in the author's quasi-three-dimensional turbomachinery analysis code. The code includes the effects of rotation, radius change, and stream-surface thickness variation, and also includes the B-L turbulence model. The kappa-omega model was implemented using many of Menter's recommendations and an implicit approximate-factorization scheme described by Baldwin and Barth. The model was tested for a transonic compressor with rotation and variable stream-surface radius and height, and for a transonic turbine vane with transition and heat transfer. Results were compared to the B-L model and to experimental data.
Chima, Rodrick V.↗
Characterizing Cometary Electrons with Kappa Distributions
The Rosetta spacecraft has escorted comet 67P/Churyumov-Gerasimenko since 6 August 2014 and has offered an unprecedented opportunity to study plasma physics in the coma. We have used this opportunity to make the first characterization of cometary electrons with kappa distributions. Two three-dimensional kappa functions were fit to the observations, which we interpret as two populations of dense and warm (density 10 cubic centimeters, temperature 2 times 10 (sup 5) degrees Kelvin, invariant kappa index 10 to 1000), and rarefied and hot (density equals 0.005 cubic centimeters, temperature 5 times 10 (sup 5) degrees Kelvin, invariant kappa index equals 1 to 10) electrons. We fit the observations on 30 October 2014 when Rosetta was 20 kilometers from 67P, and 3 Astronomical Units from the Sun. We repeated the analysis on 15 August 2015 when Rosetta was 300 kilometers from the comet and 1.3 Astronomical Units from the Sun. Comparing the measurements on both days gives the first comparison of the cometary electron environment between a nearly inactive comet far from the Sun and an active comet near perihelion. We find that the warm population density increased by a factor of 3, while the temperature cooled by a factor of 2, and the invariant kappa index was unaffected. We find that the hot population density increased by a factor of 10, while the temperature and invariant kappa index were unchanged. We conclude that the hot population is likely the solar wind halo electrons in the coma. The warm population is likely of cometary origin, but its mechanism for production is not known.
Broiles, T. W.↗
The relationship between kappa and temperature in energetic ion spectra at Jupiter
A universal energy per charge kappa function fit is simultaneously applied to the spectra of Voyager 2 Low Energy Charged Particle (LECP) proton, helium, oxygen, sulfur, and carbon ions during 33 Jovian plasma sheet crossings from 26 to 160 R(sub J). The fits yield an approximately linear relationship between high energy spectral index, kappa, and core proton temperature of the form kappa (T(sub H)) approximately = eta dot T(sub H) + kappa(sub 0) with eta = 0.080 ke/V, kappa(sub 0) = 2.86, and T(sub H) measured in keV. Core proton temperatures range from 5 to 35 keV with spectral indices ranging from 3 to 6.
Collier, Michael R.↗
Zonal Two Equation Kappa-Omega Turbulence Models for Aerodynamic Flows
Two new versions of the kappa-omega two-equation turbulence model will be presented. The new Baseline (BSL) model is designed to give results similar to those of the original kappa-omega model of Wilcox, but without its strong dependency on arbitrary freestream values. The BSL model is identical to the Wilcox model in the inner 50% of the boundary-layer but changes gradually to the standard kappa-epsilon model (in a kappa- omega formulation) towards the boundary-layer edge. The free shear layers. The second version of the model is called Shear-Stress Transport (SST) model. It is a variation of the BSL model with the additional ability to account for the transport of the principal turbulent shear stress in adverse pressure gradient boundary-layers. The model is based on Bradshaw's assumption that the principal shear-stress is proportional to the turbulent kinetic energy, which is introduced into the definition of the eddy-viscosity. Both models are tested for a large number of different flowfields. The results of the BSL model are similar to those of the original kappa-omega model, but without the undesirable freestream dependency. The predictions of the SST model are also independent of the freestream values but show better agreement with experimental data for adverse pressure gradient boundary-layer flows.
Menter, Florian R.↗
Importance of Considering Near-Surface Attenuation in Earthquake Source Parameter Estimation: Insights from Kappa at a Dense Array in Oklahoma
ABSTRACT Separating earthquake source spectra from propagation effects is challenging. The propagation effect contains a site-dependent term related to the high attenuation of shallow sediments. Neglecting the site-dependent attenuation can cause large biases and scattering in the corner-frequency (fc) estimates, resulting in significant stress-drop deviations. In this study, we investigate shallow attenuation at the LArge-n Seismic Survey in Oklahoma (LASSO) and site-related biases and scattering in source parameter measurements due to simplified attenuation models. We measure the high-frequency spectral decay parameter kappa on the vertical acceleration spectra of regional earthquakes (125 km away). The site-dependent kappa (κ0,acc) suggests that attenuation increases rapidly at shallow depth and is highly site-dependent. 10%–75% of the attenuation is site-dependent for S waves and even larger for P waves. The quality factor for S waves (QS) ranges from 10 to 100 in the upper 400 m. QP for P waves is mostly below 10 within the same depth. The Quaternary sediments tend to be more attenuating (QS<30), but the Permian rocks also can have high attenuation. We demonstrate that using a non-site-dependent attenuation model in single-spectra fitting leads to large scattering in fc estimates among stations with apparent good fits. The apparent fc can significantly deviate when the range of site-dependent kappa is large or with a higher assumed source spectral fall-off rate n. The biases in apparent fc depend on site condition and distance; however, the correlation between fc and these factors might not be obvious, depending on model assumptions. An apparent increase of stress drop with magnitude in a previous study for local microearthquakes (1.3
Chang, Hilary↗
Hybrid Simulation and Quasi-linear Theory of Bi-Kappa Proton Instabilities
The quasi-steady states of collisionless plasmas in space (e.g., in the solar wind and planetary environments) are governed by the interactions of charged particles with wave fluctuations. These interactions are responsible not only for the dissipation of plasma waves but also for their excitation. The present analysis focuses on two instabilities, mirror and electromagnetic ion cyclotron instabilities, associated with the same proton temperature anisotropy T ⊥ > T ∥ (where ⊥, ∥ are directions defined with respect to the local magnetic field vector). Theories relying on standard Maxwellian models fail to link these two instabilities (i.e., predicted thresholds) to the proton quasi-stable anisotropies measured in situ in a completely satisfactory manner. Here we revisit these instabilities by modeling protons with the generalized bi-Kappa (bi-κ power-law) distribution, and by a comparative analysis of a 2D hybrid simulation with the velocity-moment-based quasi-linear (QL) theory. It is shown that the two methods feature qualitative and, even to some extent, quantitative agreement. The reduced QL analysis based upon the assumption of a time-dependent bi-Kappa model thus becomes a valuable theoretical approach that can be incorporated into the present studies of solar wind dynamics.
79 ASTRONOMY AND ASTROPHYSICS↗
Absolute ultraviolet spectrophotometry of Alpha Canis Majoris, Gamma Orionis, Kappa Orionis and Alpha Leonis
Spectral observations of the stars Alpha Canis Majoris, Gamma Orionis, Kappa Orionis and Alpha Leonis have been obtained in the range 1150-4000 A, using rocket borne spectrometers. The payloads have a 13-inch diameter telescope, a rotatable concave diffraction grating, and three pulse counting photomultiplier photometers. The observations are systematically lower than those of Carruthers (1968) at 1270 A, of Smith (1967) at 1376 A, and of Campbell (1970) at 2150 and 2550 A. The data are also about 15 percent lower than the ground-based photometry reported by Schild, Peterson and Oke (1971). The OAO-2 short wavelength scanner calibration agrees with the alpha Leo observations, but disagrees for Kappa Ori and Gamma Ori.
Evans, D. C.↗
Search for optical coronal line emission from the X-ray sources Epsilon Orionis /B0 Ia/ and Kappa Orionis /B0.5 Ia/
A search was conducted for evidence of a coronal region at the base of the winds of Epsilon Ori and Kappa Ori, by means of high signal-to-noise observations at the forbidden lines of Fe X, at 6574 A, and Fe XIV, 5303 A. Both stars have been detected as soft X-ray sources, and show anomalously strong O VI lines in their UV spectra. Large coronal emission measures were expected from the total X-ray flux and Auger-enhanced ionization, but the fact that the iron coronal lines were not detected places new limits on the emission measure if the total temperature is in the range of 700,000-3,000,000 or more than 1,000,000 for Kappa Ori and 2,000,000 for Epsilon Ori. It is suggested that at least some of the X-rays arise, not from the base corona, but from source features farther out in the wind.
Nordsieck, K. H.↗
Kappa Group: The initial guess. A proposal in response to a commercial air transportation study
Kappa Aerospace presents their Aeroworld Aircraft, the Initial Guess (IG). This aircraft is designed to generate profit in the market which is currently controlled by the train and boat industry. The main priority of the design team was to develop an extremely efficient aircraft that could be sold at a reasonable price. The IG offers a quick and safe alternative to the existing means of transportation at a competitive price. The cruise velocity of 28 ft/sec. allows all flights to be between 20 and 45 minutes, which is a remarkable savings in time compared to travel by boat or train. The IG is propelled by a single Astro-05 engine with a Zinger 10-6 propeller. The Astro-05 is not an extremely powerful engine; however, it provides enough thrust to meet the design and safety requirements. The major advantage of the Astro-05 is that it is the most efficient engine available. The fuel efficiency of the Astro-05 is what puts the aircraft ahead of the competition. The money saved on an efficient engine can be passed on as lower ticket prices or increased revenue. The IG has a payload of 56 passengers and a wingspan of 7 ft. The 7 ft. wingspan allows the aircraft to fit into the gates of all of the cities that are targeted. Future endeavors of Kappa Aerospace will include fitting a stretch version of the IG with a larger propulsion system. This derivative aircraft will be able to carry more passengers and will be placed on the routes which have the greatest demand for travel. The fuselage and empennage are made of a wooden truss configuration, while the wing is made of a rib/spare configuration. The stress carrying elements are made of spruce, the nonstress carrying elements are made of balsa. The wing is removable for easy access into the fuselage. The easy access to the batteries will keep maintenance costs down.
Source record↗
A nonradial pulsation model for the rapidly rotating Delta Scuti star Kappa(2) Bootis
A sectorial nonradial pulsation model is used to construct theoretical line profiles which mimic the variations for Kappa(2) Boo. Synthetic spectra generated with the appropriate Teff and log g are used as input. It is found that the data can be reproduced by the combination of a high-degree l is approximately equal to 12 mode with P(osc) aproximately equal to 0.071 d, and a low-degree mode, l is approximately equal to 0-2 with P(osc) approximately equal to 0.071-0.079 d. The projected rotational velocity (v sin i - 115 +/-5 km/s) was determined by fitting synthetic line profiles to the observed spectra. The velocity amplitude of the high-degree oscillations is estimated to be about 3.5 km/s. It is found that the ratio of the horizontal and radial pulsation amplitudes is small (about 0.02) and consistent with p-mode oscillations. Comparisons are made with models invoking starspots, and it is impossible to fit the observations of Kappa(2) Boo by a starspot model without assuming unrealistic values of radius or equatorial velocity.
Kennelly, E. J.↗
Low Reynolds number kappa-epsilon and empirical transition models for oscillatory pipe flow and heat transfer
Stirling engine heat exchangers are shell-and-tube type with oscillatory flow (zero-mean velocity) for the inner fluid. This heat transfer process involves laminar-transition turbulent flow motions under oscillatory flow conditions. A low Reynolds number kappa-epsilon model, (Lam-Bremhorst form), was utilized in the present study to simulate fluid flow and heat transfer in a circular tube. An empirical transition model was used to activate the low Reynolds number k-e model at the appropriate time within the cycle for a given axial location within the tube. The computational results were compared with experimental flow and heat transfer data for: (1) velocity profiles, (2) kinetic energy of turbulence, (3) skin friction factor, (4) temperature profiles, and (5) wall heat flux. The experimental data were obtained for flow in a tube (38 mm diameter and 60 diameter long), with the maximum Reynolds number based on velocity being Re(sub max) = 11840, a dimensionless frequency (Valensi number) of Va = 80.2, at three axial locations X/D = 16, 30 and 44. The agreement between the computations and the experiment is excellent in the laminar portion of the cycle and good in the turbulent portion. Moreover, the location of transition was predicted accurately. The Low Reynolds Number kappa-epsilon model, together with an empirical transition model, is proposed herein to generate the wall heat flux values at different operating parameters than the experimental conditions. Those computational data can be used for testing the much simpler and less accurate one dimensional models utilized in 1-D Stirling Engine design codes.
Bauer, Christopher↗
The abundances of Pt, Au, and Hg in the chemically peculiar HgMn-type stars kappa Cancri and chi Lupi
Echelle mode spectra obtained with the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope (HST) have been used to determine the abundances of the heavy elements Pt, Au, and Hg in the chemically peculiar HgMn-type stars kappa Cancri and chi Lupi. The abundances were determined by fitting observed line profiles with synthetically generated spectra and are found to be enhanced relative to solar system values by between three and five orders of magnitude in both stars. The Hg isotope mixture in kappa Cancri is found to resemble the terrestrial mixture while that of chi Lupi is dominated by the heaviest isotope. As determined from multiple ionization states, the abundances place constraints upon theories attempting to explain the large superficial abundances of heavy elements.
Wahlgren, Glenn M.↗
Compressibility Considerations for kappa-omega Turbulence Models in Hypersonic Boundary Layer Applications
The ability of kappa-omega models to predict compressible turbulent skin friction in hypersonic boundary layers is investigated. Although uncorrected two-equation models can agree well with correlations for hot-wall cases, they tend to perform progressively worse - particularly for cold walls - as the Mach number is increased in the hypersonic regime. Simple algebraic models such as Baldwin-Lomax perform better compared to experiments and correlations in these circumstances. Many of the compressibility corrections described in the literature are summarized here. These include corrections that have only a small influence for kappa-omega models, or that apply only in specific circumstances. The most widely-used general corrections were designed for use with jet or mixing-layer free shear flows. A less well-known dilatation-dissipation correction intended for boundary layer flows is also tested, and is shown to agree reasonably well with the Baldwin-Lomax model at cold-wall conditions. It exhibits a less dramatic influence than the free shear type of correction. There is clearly a need for improved understanding and better overall physical modeling for turbulence models applied to hypersonic boundary layer flows.
Rumsey, C. L.↗
Spectral Interpretation of Radio Sounder-Stimulated Magnetospheric Plasma Resonances in Terms of Kappa Distributions
Magnetosphere sounders stimulate plasma resonances between the harmonics of the electron cyclotron frequency and above the upper-hybrid frequency. More than three decades ago they were recognized as equivalent to ionospheric topside-sounder-stimulated resonances, designated as Qn resonances a decade earlier, with one important difference: the magnetospheric Qn frequencies often indicated that the background electron-velocity distribution was non-Maxwellian. Interpretations based on bi-Maxwellian and kappa distributions have been proposed. Here we expand on the latter, which requires fewer free parameters, by comparing kappa-derived Qn frequencies with observations from the Radio Plasma Imager on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite.
Benson, Robert F.↗
Acoustics Examination of Kappa West Firing ARMAG for Personnel Occupancy
In April of 2023, LANL conducted a series of explosive tests at the Kappa West firing mound at BEEF, NNSS, to examine noise levels within the diagnostics ARMAG next to the firing mound. The intent was to establish an explosive mass that could be detonated on the mound without generating blast noise inside the ARMAG which would be unsafe for personnel. The blast noise threshold for personnel safety during intentional firing operations is 140 dB. Based on data collected during prior experiments, it was anticipated that the noise levels inside the ARMAG would be 20-30 dB lower than noise levels outside the ARMAG. However, data from prior experiments were collected from charges that were not consistent geometries and test layouts, so it was unknown what quantity of explosive would generate the threshold noise level. A prediction was made using the BEC-O standard blast calculator from the DDESB, from which it was estimated that a single, consolidated 60-pound charge at 180 feet would generate blast noise levels of about 170 dB, with noise levels falling to a predicted 166 dB at 250 feet.
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
Flux flow in materials where kappa approximates 1.
Kim-Anderson flux flow theory for materials with kappa nearly equal to 1, discussing pinning forces and sites
Hudson, W. R.↗