Teflon-packed flexible joint

Teflon-packed flexible joint separates the movement of the shaker from the liquid nitrogen hose during the ground testing of cryogenic zero-g equipment. The joint allows the hose to lie on the floor in a stationary position as the shaker moves back and forth, thus, the hose is not subject to violent motion

Comparison of periodic and other characteristics of geomagnetic and meterological rocket data

The temporal variations in stratospheric winds and temperatures with the geomagnetic field elements were compared. From a periodic analysis of the geomagnetic field elements the amplitude and phase of the quasibiennial, annual, and semiannual waves are given for stations from 1 degree S to 89 degree N. These results are then compared with corresponding waves reported in rocketsonde wind and temperature data. The annual waves are found to be coupled as a result of the annual variation in the dynamo effect of the wind in the lower ionosphere. The semiannual waves are also found to be coupled and three possible causes for the extra tropical stratospheric semiannual wind wave are discussed. Time variance spectra for the interval from 4 days to 44 days in both zonal winds and horizontal geomagnetic field intensity are compared for years when major midwinter warmings occur and years when only minor warmings occur. The noted differences are suggested to arise from upward propagating planetary waves which are absorbed or refracted in varying amounts depending on the prevailing circulation

Periodic variations stratospheric temperature from 20-65 km at 80 deg N to 30 deg S

Results for a seasonally varying diurnal tide in temperature at Churchill are presented, and possible significant aliasing of longer period waves by this tide is discussed. A diurnal tide whose amplitude and phase are coherent throughout the year is found to have little effect on periodic amplitudes other than the long-term mean, because most rocketsonde observations are taken near the same local time each day. Errors in periodic components arising from lack of solar radiation corrections are found to be largest for the long-term mean with a small influence noted in the annual wave's amplitude. Spatial variations of the amplitudes and phases of long-period waves are examined through the use of height-latitude sections, 20-65 km, at 80 deg N to 30 deg S. The quasi-biennial oscillation and semiannual waves have tropical maxima of 2 and 3C near 30 and 40 km respectively. The annual wave's maximum is over 22C near 45 km at 70 deg N and the terannual wave's maximum is over 6C near 55 km at 80 deg N. The semiannual wave has to polar maxima: 7C near 75 deg N at 32 km and 3C above 60 km north of 35 deg N

Periodic variations in stratospheric meridional wind from 20-65 km, at 80 deg N to 8 deg S

The variability of stratospheric meridional winds is examined in both space and time. Height-latitude sections for January along 70 deg E and 90 deg W show a divergence zone above 50 km near 60 deg N and an intense convergence zone 40 km near 50 deg N over North America. This latter structure, with southward winds in the Arctic and northward winds at mid-latitudes over North America, persists from October through April. Tidal winds dominate all other circulation features in summer at all latitudes, and throughout the year at low latitudes. To help understand the observed patterns of variability, long-term periodic features are analyzed. The quasi-biennial oscillation, annual wave, and four-month wave have amplitudes of about 10, 20, and 10 m/sec respectively in the Arctic near 45 km. The phase of the annual wave changes by nearly 180 deg in a narrow zone near 45 deg N. The semiannual wave has an amplitude of 10 m/sec. 50 deg N above 50 km equinoctial phase dates in the region of maximum amplitude. This polar semiannual wave corresponds closely to that previously found in the zonal wind

Stratospheric circulation studies based on Tiros 7, 15-micron data Final report

Stratospheric temperature distribution data based on Tiros 7 radiometer dat

STUDY OF A SINGLE-CHARGED IONS ECR SOURCE MATCHING OF THE EXTRACTED BEAM TO AN ISOTOPE SEPARATOR

A new ECR ion-source has been designed and studied for single-charged ion beams. A very stable regime has been obtained with an ion-source made of two identical stages in cascade. The RF power supplies consist of two 2.45 GHz magnetrons. The discharge chamber is made of two coaxial Pyrex tubes. The external one ensures vacuum and HT insulation. The tubes are aligned inside the two multimode cavities axially limited by three magnetic coils. The ion beam is extracted at 20 kV and focused with electric lenses. For argon and xenon, 1 mA single-charged ion currents have been extracted. The influence of various parameters has been progressively achieved with a set-up including a 60° analyzing magnet and with the 120° on-line isotope separator at SARA. From emittances and images observed it appears difficult to compensate charge space effects. Suggestions and future developments are proposed to improve qualities of the isotopic separation

CFD Simulations for Sensitivity Analysis of Different Parameters to the Wake Characteristics of Tidal Turbine

articleThis paper investigates the sensitivity of width proximity and mesh grid size to the wake characteristics of Momentum Reversal Lift (MRL) turbine using a new computational fluid dynamics (CFD) based Immersed Body Force (IBF) model. This model has been added as a source term into the large eddy simulation (LES), which is developed for solving two phase fluids. The open source CFD code OpenFOAM was used for the simulations. The simulation results showed that the grid size and width proximity have had massive impact on the flow characteristics and the computational cost of the tidal turbine. A fine grid size and large width inflicted longer computational time. In contrast, a coarse grid size and small width reduced the computational time but showed poor description of the flow features. In addition, a close proximity of the domain’s wall boundary to the turbine affected the free surface, the air body, and the flow characteristics at the interface between the two phases. These results showed that careful investigation of a suitable grid size and spacing between the wall boundary and the turbine is important to minimise the effect of these parameters on the simulation results.University of Exete

Plasma Diffusion in Self-Consistent Fluctuations

The problem of particle diffusion in position space, as a consequence ofeleclromagnetic fluctuations is addressed. Numerical results obtained with a self-consistent hybrid code are presented, and a method to calculate diffusion coefficient in the direction perpendicular to the mean magnetic field is proposed. The diffusion is estimated for two different types of fluctuations. The first type (resuiting from an agyrotropic in itiai setting)is stationary, wide band white noise, and associated to Gaussian probability distribution function for the magnetic fluctuations. The second type (result ing from a Kelvin-Helmholtz instability) is non-stationary, with a power-law spectrum, and a non-Gaussian probabi lity distribution function. The results of the study allow revisiting the question of loading particles of solar wind origin in the Earth magnetosphere

Scaling of the electron dissipation range of solar wind turbulence

Electron scale solar wind turbulence has attracted great interest in recent years. Clear evidences have been given from the Cluster data that turbulence is not fully dissipated near the proton scale but continues cascading down to the electron scales. However, the scaling of the energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 years of the Cluster search-coil magnetometer (SCM) waveforms measured in the solar wind and perform a statistical study of the magnetic energy spectra in the frequency range [$1, 180$]Hz. We show that a large fraction of the spectra exhibit clear breakpoints near the electon gyroscale $\rho_e$, followed by steeper power-law like spectra. We show that the scaling below the electron breakpoint cannot be determined unambiguously due to instrumental limitations that will be discussed in detail. We compare our results to recent ones reported in other studies and discuss their implication on the physical mechanisms and the theoretical modeling of energy dissipation in the SW.Comment: 10 pages, submitte