Sample records for jovian plasma torus

  1. Interaction of Europa with Jovian Plasma Torus

    NASA Astrophysics Data System (ADS)

    Travnicek, Pavel M.; Sebek, Ondrej; Bale, Stuart D.; Hellinger, Petr; Halekas, Jasper

    2015-04-01

    We present results of a simulation study of the interaction of Europa with Jupiter's magnetospheric plasma compared to in situ observations of Galileo spacecraft. For simulations we use multi-species hybrid (kinetic ions and fluid electrons) three-dimensional model. We consider O++, S++ as the main constituents of the Jovian plasma torus at Europa while its neutral atmosphere is considered to be composed primarily of (neutral) O2 molecules. We consider ionization processes of the neutral O2 atmosphere which is then a source of dense population of pick-up ions at Europa. We examine global structure of the interaction and we compare the simulated results with in situ measurements of spacecraft Galileo. The plasma composed of pick-up ions represents an obstacle for the Jovian magnetic field resulting in the compression of the magnetic field lines which in return causes development of temperature anisotropies. We study the regions where the threshold of temperature anisotropy driven instabilities has been reached. We also focus on the refiling processes of the small cavity formed in the plasma downstream the relative plasma flow between Europa and the magnetospheric plasma. We acquire high resolution simulated data along virtual trajectories of Galileo spacecraft which allows us to directly compare simulation results to in situ observations.

  2. Preliminary Results from a Coordinated Hisaki/Chandra/XMM-Newton Study of the Jovian Aurora and Io Plasma Torus

    NASA Technical Reports Server (NTRS)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randy; Badman, Sarah Victoria; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen S.; Roediger, Elke; Tsuchiya, Fuminori; Yamazaki, Atsushi; Yoshikawa, Ichiro; Yoshioka, Kazuo

    2014-01-01

    We present preliminary results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus. The data were taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument for roughly 12 hours per observation, and twice by XMM-Newton. The goal of this observational campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  3. Jovian Plasmas Torus Interaction with Europa. Plasma Wake Structure and Effect of Inductive Magnetic Field: 3D Hybrid Kinetic Simulation

    NASA Technical Reports Server (NTRS)

    Lipatov, A. S.; Cooper, J F.; Paterson, W. R.; Sittler, E. C., Jr.; Hartle, R. E.; Simpson, David G.

    2013-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to a variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions). Photoionization, electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider the models with Oþ þ and Sþ þ background plasma, and various betas for background ions and electrons, and pickup electrons. The majority of O2 atmosphere is thermal with an extended non-thermal population (Cassidy et al., 2007). In this paper, we discuss two tasks: (1) the plasma wake structure dependence on the parameters of the upstream plasma and Europa's atmosphere (model I, cases (a) and (b) with a homogeneous Jovian magnetosphere field, an inductive magnetic dipole and high oceanic shell conductivity); and (2) estimation of the possible effect of an induced magnetic field arising from oceanic shell conductivity. This effect was estimated based on the difference between the observed and modeled magnetic fields (model II, case (c) with an inhomogeneous Jovian magnetosphere field, an inductive magnetic dipole and low oceanic shell conductivity).

  4. Plasma energization in the Jovian system

    NASA Astrophysics Data System (ADS)

    Fränz, M.; Krupp, N.; Roussos, E.; Wang, X.-D.

    2014-04-01

    Jupiter and its moons form the most diverse plasma laboratory in the solar system. Because of its chemical composition and energetic range measuring and understanding the dynamics of the Jovian plasma has been a challenge for all missions visiting the planet and its moons. In this paper we try to reconstruct energy spectra obtained by the Galileo PLS and EPD sensors in different locations of the Jovian system and discuss the instrumental limitations of this mission in comparison to the capabilities of the Juno and JUICE missions to Jupiter. We also discuss observations relevant for the plasma interaction with the Jovian moons Callisto, Europa and Ganymede in context of the JUICE mission.

  5. Studies of Io's atmosphere and plasma torus

    NASA Astrophysics Data System (ADS)

    Moreno, Miguel Angel

    Jupiter's hot and cold plasma tori and the atmosphere of Io, a jovian moon located in a nearly circular orbit at a distance of 5.9 jovian radii from the center of Jupiter are examined. The hot and cold plasma tori are centered at 5.7 and 5.3 jovian radii from Jupiter. For the hot torus the ion partitioning and energy balance are modeled by assuming that there are independent sources of neutral sulfur and oxygen atoms, that the thermal electrons have a density of 2000/cu cm and a temperature of 5 eV. In the model of energy and mass balance of the cold torus its primary source of plasma is considered a radial diffusion inward from the hot torus. The time scale for this process is assumed to be identical to that required for energetic electrons to supply the energy necessary to power the synchrotron radiation. Charge exchange between thermal ions and an extended neutral cloud of sulfur and oxygen produces fresh ions which are accelerated to corotation by the magnetic field of Jupiter. These fresh accelerated ions are the source of energy which powers the cold torus emissions. The main ion loss mechanism is a two-step process whereby charge exchange between ions and neutral molecules transforms ions into fast neutrals. Since it is generally agreed that the source of neutrals to the hot and cold tori is the atmosphere of Io, then in order to better understand torus processes the behavior of Io's atmosphere needs to be understood. Numerical gasdynamic SO2 models of sublimation and volcanic atmospheres of Io are developed by means of computer simulations. Using a fine computational grid and the computational capabilities of the Cray supercomputers, the relevant atmospheric properties such as pressure, density, temperature, and velocity are found. Day side and night side atmospheres were investigated. It was found that volcanoes form an extended atmosphere on Io. A sublimation H2S atmosphere was also investigated.

  6. Jovian's plasma torus interaction with Europa. Plasma wake structure: 3D hybrid kinetic simulation and comparison with E4 flyby Galileo's observations

    NASA Astrophysics Data System (ADS)

    Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.

    2010-12-01

    Abstract The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from Galileo orbital mission and for planning flyby and orbital measurements for future missions. The simulations are based on recent models of the atmosphere of Europa [1,2,3]. In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ions velocity distribution and the fluxes along the magnetic field [4]. Photoionization, electron-impact ionization and charge exchange are included in our model. The temperature of the background electrons and pickup electrons was also included into the generalized Ohm's law. The background plasma contains O++, S++ thermal ions and energetic ions [5]. The pickup ions were created from the atmosphere. The majority of O2 atmosphere is thermal with an extended non-thermal population [1]. The moon is modeled in this initial work as a weakly conducting body. The first results of 3D hybrid kinetic simulation of Europa's environment in absence and with the induced magnetic dipole moment were presented in [4]. In this report we discuss the results of the hybrid kinetic simulation of Europa's environment and plasma wake for various temperatures of the atmospheric atom and we provide a comparison with observation data (E4 pass, [5]) and MHD simulations.

  7. Detection of Jovian whistler mode chorus; implications for the Io torus aurora

    SciTech Connect

    Coroniti, F.V.; Scarf, F.L.; Kennel, C.F.; Kurth, W.S.; Gurnett, D.A.

    1980-01-01

    Near the Io torus outer boundary (Lapprox. =8), the Voyager 1 plasma wave instrument detected high frequency (f) waves near one-half the electron cyclotron frequency f/sub c/. High resolution waveform measurements demonstrate that these fapprox. =F/sub c//2 signals are banded whistler mode chrous at f< or approx. =f/sub c//2 and half-cyclotron frequency emissions with f slightly above f/sub c//2. The high resolution spectral information, and the theory of whistler mode waves, permit us to estimate the density (approx.2.5 cm/sup -3/), energy (few keV), and omnidirectional energy flux (10/sup 2/ ergs/cm/sup 2/-sec) of the electrons resonant with the chorus. Chorus precipitates about 6 ergs/cm/sup 2/-sec of few keV electron energy to the Jovian ionosphere at L=8. Electrostatic emission, probably electron cyclotron half-harmonic modes, have also been detected near the magnetic equator in the Io torus region. At L=8, the multimode pitch-angle diffusion associated with the detected waves should produce a precipitation flux about a factor two below the 50 ergs/cm/sup 2/-sec required to generate the observed auroral emission; however, the flux could well be larger deeper within the torus.

  8. Observations of Plasmas in the Jovian Magnetosphere

    Microsoft Academic Search

    L. A. Frank; K. L. Ackerson; J. H. Wolfe; J. D. Mihalov

    1976-01-01

    Large intensities of low-energy protons were observed deep within the Jovian magnetosphere with the plasma instrumentation on Pioneer 10 during the encounter of this space probe with Jupiter. The energy range of the electrostatic analyzer was 108 eV to 4.80 keV during encounter. Inside the flux tubes of the Galilean moon Io is a 'plasmasphere' of protons with relatively high

  9. UV Observations of the Io Plasma Torus from New Horizons and Rosetta

    Microsoft Academic Search

    Andrew J. Steffl; M. F. A'Hearn; J. L. Bertaux; P. D. Feldman; G. R. Gladstone; J. W. Parker; K. D. Retherford; D. C. Slater; S. A. Stern; M. Versteeg; H. A. Weaver

    2007-01-01

    During the New Horizons flyby of Jupiter in February 2007, the Alice UV spectrograph obtained numerous high-quality spectra of the Io plasma torus. As New Horizons flew down the Jovian magnetotail, the Alice instrument on that spacecraft was not able to observe the Io torus due to solar elongation constraints. However, a nearly identical Alice UVS instrument aboard the Rosetta

  10. Plasma in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.

    1975-01-01

    It is shown that the plasma in Jupiter's ionosphere is collisionless above a certain level. In the outer magnetosphere, where the rotational force dominates the gravitational force, the collisionless plasma has a beam-like distribution and gives rise to a two-stream instability. This leads to trapping of plasma in the centrifugally dominated region of the magnetosphere. Plasma is lost by recombination. Equilibrium-trapped particle densities are calculated by requiring a balance between trapping by wave-particle interaction and loss by recombination. The results are compared with recent observations from Pioneer 10. It is suggested that the observations require an unexplained ion-heating mechanism. Some consequences of the model are discussed.

  11. Hot plasma heavy ion abundance in the inner Jovian magnetosphere (\\/<10 Rj)

    Microsoft Academic Search

    C. G. Maclennan; L. J. Lanzerotti; A. Lagg

    2001-01-01

    Knowledge of the hot plasma components of the Jovian environment is important for several scientific problems, including the acceleration and transport of Jovian plasmas, the stability of the plasma sheet, and the bombardment, implantation, and sputtering of the surfaces of Jovian moons, especially Europa. The multiple flybys of the Jovian moon Europa during the Galileo mission have provided the opportunity

  12. Hot plasma heavy ion abundance in the inner Jovian magnetosphere (<10 R j)

    Microsoft Academic Search

    C. G. Maclennan; L. J. Lanzerotti; Andreas Lagg

    2001-01-01

    Knowledge of the hot plasma components of the Jovian environment is important for several scientific problems, including the acceleration and transport of Jovian plasmas, the stability of the plasma sheet, and the bombardment, implantation, and sputtering of the surfaces of Jovian moons, especially Europa. The multiple flybys of the Jovian moon Europa during the Galileo mission have provided the opportunity

  13. Ground based observations of Io plasma torus variability

    NASA Astrophysics Data System (ADS)

    Pinho Magalhães, Fabíola; Echer, Ezequiel; Demétrio Gonzalez Alarcon, Walter; Lopes, Rosaly; Morgenthaler, Jeffrey; Echer, Mariza P. S.

    Jupiter is not only the largest planet in the Solar System, it also has the largest magnetosphere. Jupiter's innermost Galilean moon, Io, is the most volcanically active body in the Solar System. This volcanic activity produces tenuous atmosphere which escapes, creating the Io plasma torus, a ring of charged particles encircling Jupiter. The Io plasma torus is composed mainly of sulfur and oxygen ions. It is most dense around Io's orbit (5.6 Rj). It's observed in extreme ultraviolet (EUV) emission and in the optical. EUV emission arise from interactions between torus superthermal ("hot") electrons and ions. Optical emission comes from interaction between thermal electrons and sulfur ions. The optical emission trace the densest part of the torus, the EUV trace the hottest part of the torus. In early December, 2013, we observed the Io plasma torus at the McMath-Pierce Solar Telescope using a specially designed coronagraph in support of the JAXA EXtrem ultraviolet spectrosCope for ExophEric Dynamics (EXCEED) mission. EXCEED is observing the Io plasma torus in the EUV in a manner similar to that of the landmark observations made by the Cassini UVIS instrument in 2000. Our ground-based [SII] 6731 angstrom images provide context for the EXCEED observations. The analysis of the 2013 [SII] data is important preparation for analysis of a much larger set of observations recorded between 1997 and 2008. This large set of over 1000 images were recorded during the Galileo tour, the Cassini flyby, and the Ulysses flyby of Jupiter. The images provide context for in-situ observations, EUV images, and several new measurements of the mysterious and variable Jovian magnetospheric "system IV" period. In this work, we'll be presenting a comparison between our results and EXCEED's and the methodology which will be used for the 1000 images.

  14. Jovian magnetospheric plasma effects at Europa and Ganymede (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Cassidy, T. A.; Hendrix, A. R.; Paranicas, C.; Cipriani, F.; Leblanc, F.; Cooper, J. F.

    2009-12-01

    Europa and Ganymede are imbedded in the Jovian magnetospheric plasma. This plasma alters their surfaces producing tenuous surface boundary-layer atmospheres (Johnson, 2002). That is, the interactions of the desorbed neutrals with the surface determine the composition and morphology of their atmospheres (Cassidy et al. 2009; Cipriani et al. 2009). Those neutrals that escape the satellite remain gravitationally bound to Jupiter in a toroidal-shaped cloud until they are ionized and contribute to the ambient plasma. Since gas-phase species are readily identified, the gravitationally bound and toroidal components are of interest as extensions of the satellite’s surface. If these atmospheres were only populated by thermal desorption, they would have a small subsolar water component (Shematovich et al. 2005) and the trace volatiles would be rapidly depleted. However, Europa and Ganymede orbit in a region of the Jovian magnetosphere in which the trapped plasma density and temperature are relatively high. This plasma and the solar EUV flux chemically alter and erode their surfaces, processes often lumped together as sputtering. Early laboratory results were used to predict the principal atmospheric component, O2, and its average column density (Johnson et al. 1982). Since loss of H2 accompanies the formation and ejection of O2 from ice (Johnson and Quickenden 1997), and, since H2 escapes more readily than the heavier species, hydrogen is a principal species in the neutral torus (Smyth and Marconi 2006) and a primary source of protons for the Jovian magnetosphere. Atmospheric simulations using models for the surface composition, data on the radiation flux, and laboratory data have been used in to interpret the available observations and to suggest which trace species might be detectable by an orbiting spacecraft. Models for the atmospheres of Europa and Ganymede and their relation to the plasma-weathered surfaces will be described in which redistribution and loss to the surface compete with loss due to ionization and pick-up, direct escape, and dissociation. Our interest is the relationship of the morphology and composition of the atmosphere and to its surface properties and the possibility of detection of atmospheric species (Johnson et al. 2009). References: Cassidy, T.A., et al, Trace constituents of Europa's atmosphere, Icarus (2009) Cipriani, F., et al, Exospheric signatures of alkali abundances in Europa's regolith, GRL 36, 2009 Johnson, R.E., et al. Planetary applications of ion-induced erosion of condensed-gas-frost.NuclInstrMethods 198, 147-157, 1982. Johnson, R.E., T.I.Quickenden, Photolysis & Radiolysis of Ice on Outer Solar System Bodies, JGR 102, 10985, 1997. Johnson, R.E., Surface Boundary Layer Atmospheres, in Atmospheres in the Solar System: Comparative Aeronomy Geophys.Mono. 130, 203-219 (2002) Johnson, R.E., et al."Composition and Detection of Europa's Sputter-Induced Atmosphere", in Europa, Eds. R. Pappalardo et al. (2009) in press. Shematovich, V.I., et al "Surface-bounded Atmosphere of Europa", Icarus 173, 480-498 (2005). Smyth W.H.,M.L. Marconi, Europa's atmosphere, gas tori, and magnetospheric implications, 181, 2, 510-526, 2006

  15. Jovian ionospheric conductivity and magnetospheric plasma outflow - Voyager 1

    NASA Astrophysics Data System (ADS)

    Hairston, M. R.; Hill, T. W.

    1985-10-01

    Using magnetic field and plasma data from the Voyager 1 inbound encounter, the authors have derived local values for the mass outflow rate and the radial bulk velocity in the dayside Jovian magnetosphere, and for the height-integrated Pedersen conductivity of the Jovian ionosphere. These values, accurate within a factor of 2, are compatible with previous order-of-magnitude estimates of these quantities. The results suggest that the shape of the plasma sheet is more complicated than previously suspected. A search for evidence of enhanced plasma outflow in the active sector was inconclusive.

  16. Standing hydromagnetic waves in the Io plasma torus - Voyager 1 observations

    NASA Technical Reports Server (NTRS)

    Glassmeier, K.-H.; Neubauer, F. M.; Ness, N. F.; Acuna, M. H.

    1989-01-01

    An attempt to analyze Voyager 1 magnetic field data for the existence of any ultralow-frequency hydromagnetic waves in the Io plasma torus is presented. The coincidence between the increase in wave activity and the entry into the Io plasma torus is in support of treating the torus as a low Alfven velocity region and thus as a hydromagnetic waveguide. A first theoretical treatment of hydromagnetic wave propagation within the torus suggests that decoupling of toroidal and poloidal type oscillations can occur under the condition of axisymmetry of the wave field. Numerical calculations of the fundamental mode toroidal and first harmonic poloidal eigenperiods for a model Jovian magnetosphere give values quite in agreement with the observed periods. Observations of nearly axisymmetric, decoupled toroidal and poloidal mode eigenoscillations of the Io plasma torus suggest a large-scale source mechanism for the detected magnetic field fluctuations.

  17. Galileo Observations of the Io Plasma Torus

    NASA Astrophysics Data System (ADS)

    Nerney, E. G.; Bagenal, F.; Pryor, W. R.; Steffl, A. J.

    2014-12-01

    We present a survey of conditions observed in the Io plasma torus throughout the Galileo mission (1995 to 2003). This Galileo epoch includes the time of the Cassini flyby of Jupiter (fall 2000 to spring 2001) when the UVIS instrument made extensive observations of the spatial and temporal variations of torus emissions (Steffl et al. 2004, 2006). We compare re-analyzed Galileo EUV observations of torus emissions with a physical chemistry model based on Delamere et al. (2004) to derive modest variations in torus model parameters (transport time, neutral source, population of hot electrons, ratio of neutral oxygen to sulfur atoms in the source) over the Galileo era. Torus plasma conditions derived from these emissions are also compared with in situ measurements by the Galileo PLS and PWS instruments as well as the Cassini UVIS observations and ground-based observations of torus emissions.

  18. Detection of Jovian whistler mode chorus; implications for the Io torus aurora

    Microsoft Academic Search

    F. V. Coroniti; F.L. Scarf; C. F. Kennel; W. S. Kurth; D. A. Gurnett

    1980-01-01

    Near the Io torus outer boundary (Lapprox. =8), the Voyager 1 plasma wave instrument detected high frequency (f) waves near one-half the electron cyclotron frequency f\\/sub c\\/. High resolution waveform measurements demonstrate that these fapprox. =F\\/sub c\\/\\/2 signals are banded whistler mode chrous at f< or approx. =f\\/sub c\\/\\/2 and half-cyclotron frequency emissions with f slightly above f\\/sub c\\/\\/2. The

  19. The dynamic expansion and contraction of the Jovian plasma sheet

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Mcnutt, R. L., Jr.

    1980-01-01

    Observations suggesting the sequential expansion and compression of the Jovian plasma sheet are reported. Plasma flow in the vicinity of Jupiter was monitored by the four modulated-grid Faraday cups on board each of the Voyager spacecraft at times of closest Jupiter approach. Sensor measurements reveal the flow of magnetospheric plasma to be directed away from the equatorial current sheet near local noon and to be directed towards the sheet in the dusk to midnight sector. The observed flow patterns are interpreted in terms of short-time-scale perturbations of magnetic flux tubes due to the compression of the dayside magnetosphere by the solar wind. It is noted that such a dynamic motion is quite different from what would be expected of slower, quasi-static equilibrium plasma sheet expansion and contraction.

  20. Io plasma torus electrons - Voyager 1

    NASA Astrophysics Data System (ADS)

    Sittler, E. C.; Strobel, D. F.

    1987-06-01

    A thermal Maxwellian component of the electron distribution function, together with a suprathermal, non-Maxwellian one, are featured in the present analysis of in situ plasma electron observations made by the Voyager 1 plasma science experiment in the Io plasma torus. A large difference in the hot electron pressure P(H) is noted between the inbound and the outbound data; this is interpreted as a latitudinal gradient, with P(H) being maximum at the magnetic equator. The presence of a neutral corona around Io is inferred from the observed decrease and symmetry with respect to Io of the cold electron temperature.

  1. Origin and energetics of the Io plasma torus

    Microsoft Academic Search

    A. A. Galeev; I. Ch. Chabibrachmanov

    1983-01-01

    The ionization of the gas ejections from the Io satellite into the Jovian magnetosphere by the corotating magnetospheric plasma flow is considered. It is shown that the plasma flow velocity at the Io orbit exceeds the critical velocity at which the anomalous electron ionization of the heavy gas components takes place due to collisionless energy transfer from ionized gas atoms

  2. The physics of spherical torus plasmas

    NASA Astrophysics Data System (ADS)

    Peng, Y.-K. M.

    2000-05-01

    Broad and important progress in plasma tests, theory, new experiments, and future visions of the spherical torus (ST, or very low aspect ratio tokamaks) have recently emerged. These have substantially improved our understanding of the potential properties of the ST plasmas, since the preliminary calculation of the ST magnetohydrodynamic equilibria more than a decade ago. Exciting data have been obtained from concept exploration level ST experiments of modest capabilities (with major radii up to 35 cm), making important scientific contributions to toroidal confinement in general. The results have helped approval and construction of new and/or more powerful ST experiments, and stimulated an increasing number of theoretical calculations of interest to magnetic fusion energy. Utilizing the broad knowledge base from the successful tokamak and advanced tokamak research, a wide range of new ST physics features has been suggested. These properties of the ST plasma will be tested at the 1 MA level with major radius up to ˜80 cm in the new proof of principle devices National Spherical Torus Experiment (NSTX, U.S.) [M. Peng et al., European Conf. Abst. 22C, 451 (1998); S. M. Kaye et al., Fusion Technol. 36, 16 (1999); M. Ono et al., "Exploration of Spherical Torus Physics in the NSTX Device," 17th IAEA Fusion Energy Conf., paper IAEA-CN-69/ICP/01 (R), Yokohama, Japan (1998)], Mega Ampere Spherical Tokamak (MAST, U.K.) [A. C. Darke et al., Fusion Technol. 1, 799 (1995); Q. W. Morris et al., Proc. Int. Workshop on ST (Ioffe Inst., St. Petersburg, 1997), Vol. 1, p. 290], and Globus-M (R.F.) [V. K. Gusev et al., European Conf. Abst. 22C, 576 (1998)], which have just started full experimental operation. New concept exploration experiments, such as Pegasus (University of Wisconsin) [R. Fonck and the PEGASUS Team, Bull. Am. Phys. Soc. 44, 267 (1999)], Helicity Injected Tokamak-II (HIT-II, University of Washington) [T. R. Jarboe et al., Phys. Plasmas 5, 1807 (1998)], and Current Drive Experiment-Upgrade (CDX-U, Princeton Plasma Physics Laboratory) [M. Ono et al., Proceedings of the 16th International Conference on Fusion Energy (IAEA, Vienna, 1997), Vol. 2, p. 71] and other experiments in Japan and Brazil, etc., present additional opportunities for important progress. This tutorial paper summarizes our understanding and projections of the physics of the ST plasmas, the investigation of which will hopefully bring new enthusiasm and advancements for fusion energy science research in the U.S. and the world.

  3. The transmission of Alfven waves through the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Wright, A. N.; Schwartz, S. J.

    1989-04-01

    The nature of Alfven wave propagation through the Io plasma torus was investigated using a one-dimensional model with uniform magnetic field and an exponential density decrease to a constant value. The solution was interpreted in terms of a wave that is incident upon the torus, a reflected wave, and a wave that is transmitted through the torus. The results obtained indicate that Io's Alfven waves may not propagate completely through the plasma torus, and, thus, the WKB theory and ray tracing may not provide meaningful estimates of the energy transport.

  4. The Jovian Plasma Dynamics and Composition Analyzer for the Particle Environment Package on JUICE

    NASA Astrophysics Data System (ADS)

    Wieser, Martin; Barabash, Stas; Stude, Joan

    2015-04-01

    The Jovian plasma Dynamics and Composition analyzer (JDC) is one of six sensors of Particle Environment Package (PEP) on ESA's JUICE mission to Jupiter. JDC measures 3D distribution functions of positive and negative ions in the energy range 1eV per charge to 41keV per charge. The sensor measures simultaneously using a high sensitivity-low mass resolution and a lower sensitivity-high mass resolution channel and has the additional capability to measure electrons. Instrument mass constraints and the jovian radiation environment drive the design of the sensor: radiation shielding, detectors and coincidence systems are optimized for the plasma and radiation environment to be expected during the JUICE mission while keeping the sensor mass within allocated limits. We present the JDC sensor principle and design and its predicted performance in the jovian environment and compare to laboratory measurements from JDC sensor prototypes.

  5. Ion Temperature Control of the Io Plasma Torus

    NASA Technical Reports Server (NTRS)

    Delamere, P. A.; Schneider, N. M.; Steffl, A. J.; Robbins, S. J.

    2005-01-01

    We report on observational and theoretical studies of ion temperature in the Io plasma torus. Ion temperature is a critical factor for two reasons. First, ions are a major supplier of energy to the torus electrons which power the intense EUV emissions. Second, ion temperature determines the vertical extent of plasma along field lines. Higher temperatures spread plasma out, lowers the density and slows reaction rates. The combined effects can play a controlling role in torus energetics and chemistry. An unexpected tool for the study of ion temperature is the longitudinal structure in the plasma torus which often manifests itself as periodic brightness variations. Opposite sides of the torus (especially magnetic longitudes 20 and 200 degrees) have been observed on numerous occasions to have dramatically different brightness, density, composition, ionization state, electron temperature and ion temperature. These asymmetries must ultimately be driven by different energy flows on the opposite sides, presenting an opportunity to observe key torus processes operating under different conditions. The most comprehensive dataset for the study of longitudinal variations was obtained by the Cassini UVIS instrument during its Jupiter flyby. Steffl (Ph.D. thesis, 2005) identified longitudinal variations in all the quantities listed above wit the exception of ion temperature. We extend his work by undertaking the first search for such variation in the UVIS dataset. We also report on a 'square centimeter' model of the torus which extend the traditional 'cubic centimeter' models by including the controlling effects of ion temperature more completely.

  6. High resolution measurements of density structures in the Jovian plasma sheet

    NASA Technical Reports Server (NTRS)

    Ansher, J. A.; Kurth, W. S.; Gurnett, D. A.; Goertz, C. K.

    1991-01-01

    A recent effort to digitize the plasma density by using the low frequency cutoff of trapped continuum radiation in the vicinity of the Jovian plasma sheet has revealed the existence of sharply defined density structures in the plasma sheet. These structures typically have a plasma density which is relatively constant but of order 50 percent greater or less than in the surrounding plasma. At the boundaries of these structures, the transitions from low to high density occur on time scales of about ten seconds, which correspond to spatial dimensions on the order of a few ion Larmor radii. The structures themselves last for intervals from less than a minute to more than five minutes, corresponding to size scales from a fraction of a Jovian radius to more than a Jovian radius, depending of the velocity of the structure relative to the spacecraft. In view of the importance of near corotation plasma flows, these structures are likely to be limited in both the longitudinal and radial dimensions and, therefore, could represent flux tubes with greatly varying plasma content. These observations are presented as among the first to directly address the theoretically proposed interchange instability.

  7. Physics of the Jovian Magnetosphere

    NASA Astrophysics Data System (ADS)

    Dessler, A. J.

    2002-08-01

    List of tables; Foreword James A. Van Allen; Preface; 1. Jupiter's magnetic field and magnetosphere Mario H. Acuña, Kenneth W. Behannon and J. E. P. Connerney; 2. Ionosphere Darrell F. Strobel and Sushil K. Atreya; 3. The low-energy plasma in the Jovian magnetosphere J. W. Belcher; 4. Low-energy particle population S. M. Krimigis and E. C. Roelof; 5. High-energy particles A. W. Schardt and C. K. Goertz; 6. Spectrophotometric studies of the Io torus Robert A. Brown, Carl B. Pilcher and Darrell F. Strobel; 7. Phenomenology of magnetospheric radio emissions T. D. Carr, M. D. Desch and J. K. Alexander; 8. Plasma waves in the Jovian magnetosphere D. A. Gurnett and F. L. Scarf; 9. Theories of radio emissions and plasma waves Melvyn L. Goldstein and C. K. Goertz; 10. Magnetospheric models T. W. Hill, A. J. Dessler and C. K. Goertz; 11. Plasma distribution and flow Vytenis M. Vasyliunas; 12. Microscopic plasma processes in the Jovian magnetosphere Richard Mansergh Thorne; Appendixes; References; Index.

  8. Disentangling Electron Temperature and Density in the Io Plasma Torus

    NASA Astrophysics Data System (ADS)

    Herbert, Floyd; Hall, Doyle T.

    1997-07-01

    % \\def\\Rj {R\\dn J} One of the torus characteristics of most interest for understanding torus energization is its electron temperature (T_e). Yet deriving T_e has always been difficult because the measured quantity (emission brightness) is controlled jointly by T_e and a second unknown, electron density. In order to solve this problem, we have used a new technique to estimate T_e from spectral images of the Io plasma torus in the 350 to 700 AA region obtained by the Extreme Ultraviolet Explorer (EUVE). Because of the lack of information available on the collision strengths of important lines between 350 and 600 AA, we have attempted to simultaneously deduce both the unknown collision strengths and also the time-varying torus characteristics by fitting analytic models which exploit the both the commonalities and the variations among the observations. However, because of present limitations of the method, we can only deduce relative variations in torus T_e, total electron number (N_e -- a proxy for total torus mass), and ionic composition. In the 1993 - 1995 data set, T_e and N_e were strongly anti-correlated, while total torus luminosity remained steadier than either T_e or N_e. The anti-correlation of N_e and T_e suggests that torus luminosity may be primarily determined by a relatively constant power-limited energy supply, so that as N_e increases (decreases), T_e sags (surges) in response. A corollary to this hypothesis would be that the mass loading rate is only weakly coupled to torus energization, contradicting the class of plasma torus models called ``neutral cloud theory.'' There also seems to have been an abrupt 20% decrease in N_e at about the time of the comet Shoemaker-Levy 9 impacts on Jupiter, as though a magnetospheric disturbance had increased the convective loss rate of the torus, but this may well be a coincidence. Simultaneous ground-based observations of the 6731 AA line do not constrain N_e decreases of this size, despite their low sensitivity to T_e, because they measure total torus mass only approximately.

  9. Remote sensing of possible plasma density bubbles in the inner Jovian dayside magnetosphere

    Microsoft Academic Search

    W. M. Farrell; M. L. Kaiser; W. S. Kurth; M. D. Desch; D. A. Gurnett; G. B. Hospodarsky; R. J. MacDowall

    2004-01-01

    During the 2001 Cassini encounter with Jupiter, the Radio and Plasma Wave Science (RPWS) instrument detected fine spectral and temporal structure with broadband kilometric radiation. Applying known electron cyclotron harmonic radiation models, this microstructure is interpreted as originating from a plasma density depletion or bubble at the edge of the Io torus. The microstructure became very complicated at the event

  10. Empirical probability model of cold plasma environment in the Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Futaana, Yoshifumi; Wang, Xiao-Dong; Barabash, Stas; Roussos, Elias; Truscott, Pete

    2015-04-01

    We analyzed the Galileo PLS dataset to produce a new cold plasma environment model for the Jovian magneto- sphere. Although there exist many sophisticated radiation models, treating energetic plasma (e.g. JOSE, GIRE, or Salammbo), only a limited number of simple models has been utilized for cold plasma environment. By extend- ing the existing cold plasma models toward the probability domain, we can predict the extreme periods of Jovian environment by specifying the percentile of the environmental parameters. The new model was produced in the following procedure. We first referred to the existing cold plasma models of Divine and Garrett, 1983 (DG83) or Bagenal and Delamere 2011 (BD11). These models are scaled to fit the statistical median of the parameters obtained from Galileo PLS data. The scaled model (also called as "mean model") indicates the median environment of Jovian magnetosphere. Then, assuming that the deviations in the Galileo PLS parameters are purely due to variations in the environment, we extended the mean model toward the percentile domain. The input parameter of the model is simply the position of the spacecraft (distance, magnetic longitude and lati- tude) and the specific percentile (e.g. 0.5 for the mean model). All the parameters in the model are described in mathematical forms; therefore the needed computational resources are quite low. The new model can be used for assessing the JUICE mission profile. The spatial extent of the model covers the main phase of the JUICE mission; namely from the Europa orbit to 40 Rj (where Rj is the radius of Jupiter). In addition, theoretical extensions toward the latitudinal direction are also included in the model to support the high latitude orbit of the JUICE spacecraft.

  11. Simulation of Plasma Interaction with Io's Atmosphere

    Microsoft Academic Search

    Chris H. Moore; Hao Deng; David B. Goldstein; Deborah Levin; Philip L. Varghese; Laurence M. Trafton; Bénédicte D. Stewart; Andrew C. Walker

    2011-01-01

    One dimensional Direct Simulation Monte Carlo (DSMC) simulations are used to examine the interaction of the jovian plasma torus with Io's sublimation atmosphere. The hot plasma sweeps past Io at ~57 km\\/s due to the external Jovian magnetic and corotational electric fields and the resultant energetic collisions both heat and dissociate the neutral gas creating an inflated, mixed atmosphere of

  12. Numerical Simulation of Rotation-Driven Plasma Transport In the Jovian Magnetosphere

    NASA Technical Reports Server (NTRS)

    Wolf, Richard A.

    1997-01-01

    A Jupiter version of the Rice Convection Model (RCM-J) was developed with support of an earlier NASA SR&T grant. The conversion from Earth to Jupiter included adding currents driven by centrifugal force, reversing the planetary magnetic field, and rescaling various parameters. A series of informative runs was carried out, all of them solving initial value problems. The simulations followed an initial plasma torus configuration as it fell apart by interchange instability. Some conclusions from the simulations were the following: 1. We confirmed that, for conventional values of the torus density and ionospheric conductance, the torus disintegrates by interchange instability on a time scale of approx. one day, which is 1-2 orders of magnitude shorter than the best estimates of the average residence time of plasma in the torus. 2. In the model, the instability could be slowed to an arbitrary degree by the addition of sufficient impounding energetic particles, as suggested earlier by Siscoe et al (1981). However, the observed energetic particles do not seem sufficient to guarantee impoundment (e.g., Mauk et al., 1996). 3. Whether inhibited by impoundment or not, the interchange was found to proceed by the formation of long fingers, which get thinner as they get longer. This picture differed dramatically from the conventional radial-diffusion picture (e.g., Siscoe and Summers (1981)), more superficially with the outward-moving-blob picture (Pontius and Hill, 1989). The obvious limitation of the original RCM-J was that it could not represent a plasma source. We could represent the decay of a pre-existing torus, but we could not represent the way ionization of material from Io continually replenishes the plasma. We consequently were precluded from studying a whole set of fundamental issues of torus theory, including whether the system can come to a steady state.

  13. Role of the plasma acceleration time in the dynamics of the Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Vasyliunas, V. M.

    1994-03-01

    The time needed to accelerate plasma in the Jovian magnetosphere to the self-consistent flow imposed by coupling to the ionosphere is proportional to the Pedersen conductivity times the magnetic field divided by the flux tube content. Where this acceleration time becomes longer than the plasma outflow time, it is not possible to maintain magnetospheric plasma in corotation with the planet; comparison of the two time scales gives a general estimate of the limiting distance for corotation, identical to that previously derived by Hill from a specific flow model. At distances well beyond this limit, the magnetosphere becomes effectively decoupled from the ionosphere. In describing rotationally driven radial diffusion, inertial effects must be included whenever the acceleration time is not short compared to the eddy circulation time; they impose an upper bound on the circulation time proportional to the corotational period.

  14. Simulation of Plasma Interaction with Io’s Atmosphere

    Microsoft Academic Search

    Chris H. Moore; Hao Deng; David B. Goldstein; Deborah Levin; Philip L. Varghese; Laurence M. Trafton; Be´ne´dicte D. Stewart; Andrew C. Walker

    2011-01-01

    One dimensional Direct Simulation Monte Carlo (DSMC) simulations are used to examine the interaction of the jovian plasma torus with Io’s sublimation atmosphere. The hot plasma sweeps past Io at ?57 km?s due to the external Jovian magnetic and corotational electric fields and the resultant energetic collisions both heat and dissociate the neutral gas creating an inflated, mixed atmosphere of

  15. Low energy ion distribution measurements in Madison Symmetric Torus plasmas

    NASA Astrophysics Data System (ADS)

    Titus, J. B.; Mezonlin, E. D.; Johnson, J. A.

    2014-06-01

    Charge-exchange neutrals contain information about the contents of a plasma and can be detected as they escape confinement. The Florida A&M University compact neutral particle analyzer (CNPA), used to measure the contents of neutral particle flux, has been reconfigured, calibrated, and installed on the Madison Symmetric Torus (MST) for high temperature deuterium plasmas. The energy range of the CNPA has been extended to cover 0.34-5.2 keV through an upgrade of the 25 detection channels. The CNPA has been used on all types of MST plasmas at a rate of 20 kHz throughout the entire discharge (˜70 ms). Plasma parameter scans show that the ion distribution is most dependent on the plasma current. Magnetic reconnection events throughout these scans produce stronger poloidal electric fields, stronger global magnetic modes, and larger changes in magnetic energy all of which heavily influence the non-Maxwellian part of the ion distribution (the fast ion tail).

  16. `Mass unloading along the inner edge of the Enceladus plasma torus W. M. Farrell,1

    E-print Network

    Gurnett, Donald A.

    `Mass unloading along the inner edge of the Enceladus plasma torus W. M. Farrell,1 M. L. Kaiser,1 D ``unloaded'' along the inner edge of this plasma torus - the edge incident with the plasma-absorbing A. M. Persoon, J. E. Wahlund, and P. Canu (2008), Mass unloading along the inner edge of the Enceladus

  17. Ring current impoundment of the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Siscoe, G. L.; Eviatar, A.; Thorne, R. M.; Richardson, J. D.; Bagenal, F.; Sullivan, J. D.

    1981-09-01

    A newly discovered feature in the Io plasma formation that may be described as a ramp separating a high-density plasma ledge on its Jupiterward side from the lower-density radially distended Io plasma disc on its anti-Jupiterward side is observed to coincide with a marked inward decrease in the ring current population. The spatial congruency of the counter-directed maximal gradients in both plasma bodies reveals a profound coupling between them. The existence of the ramp requires a local order-of-magnitude reduction in the diffusion coefficient that governs radial mass transport. It is demonstrated that the diminished diffusive efficiency there is caused by strong pressure gradient inhibition of the interchange instability that underlies mass transport. The Io plasma torus, which is defined as the region of strong ultraviolet emissions, is identified as the plasma ledge. The plasma density in the ledge is high and, incidentally therefore, able to emit strongly because it is impounded against rapid, centrifugal expulsion by the inwardly directed pressure of the ring current at its inner edge.

  18. High Performance Plasmas on the National Spherical Torus Experiment

    SciTech Connect

    D.A. Gates; M.G. Bell; R.E. Bell; J. Bialek; T. Bigelow; M. Bitter; P. Bonoli; D. Darrow; P. Efthimion; J. Ferron; E. Fredrickson; L. Grisham; J. Hosea; D. Johnson; R. Kaita; S. Kaye; S. Kubota; H. Kugel; B. LeBlanc; R. Maingi; J. Manickam; T.K. Mau; R.J. Maqueda; E. Mazzucato; J. Menard; D. Mueller; B. Nelson; N. Nishino; M. Ono; F. Paoletti; S. Paul; Y-K.M. Peng; C.K. Phillips; R. Raman; P. Ryan; S.A. Sabbagh; M. Schaffer; C.H. Skinner; D. Stutman; D. Swain; E. Synakowski; Y. Takase; J. Wilgen; J.R. Wilson; W. Zhu; S. Zweben; A. Bers; M. Carter; B. Deng; C. Domier; E. Doyle; M. Finkenthal; K. Hill; T. Jarboe; S. Jardin; H. Ji; L. Lao; K.C. Lee; N. Luhmann; R. Majeski; H. Park; T. Peebles; R.I. Pinsker; G. Porter; A. Ram; M. Rensink; T. Rognlien; D. Stotler; B. Stratton; G. Taylor; W. Wampler; G.A. Wurden; X.Q. Xu; L. Zeng; and the NSTX Team

    2001-07-10

    The National Spherical Torus Experiment (NSTX) has produced toroidal plasmas at low aspect ratio (A = R/a = 0.86 m/0.68 m approximately equal to 1.3, where R is the major radius and a is the minor radius of the torus) with plasma currents of 1.4 MA. The rapid development of the machine has led to very exciting physics results during the first full year of physics operation. Pulse lengths in excess of 0.5 sec have been obtained with inductive current drive. Up to 4 MW of High Harmonic Fast Wave (HHFW) heating power has been applied with 6 MW planned. Using only 2 MW of HHFW heating power clear evidence of electron heating is seen with HHFW, as observed by the multi-point Thomson scattering diagnostic. A noninductive current drive concept known as Coaxial Helicity Injection (CHI) has driven 260 kA of toroidal current. Neutral-beam heating power of 5 MW has been injected. Plasmas with beta toroidal (= 2 mu(subscript ''0'')

    /B(superscript ''2'') = a measure of magnetic confinement efficiency ) of 22% have been achieved, as calculated using the EFIT equilibrium reconstruction code. Beta-limiting phenomena have been observed, and the maximum beta toroidal scales with I(subscript ''p'')/aB(subscript ''t''). High frequency (>MHz) magnetic fluctuations have been observed. High-confinement mode plasmas are observed with confinement times of >100 msec. Beam-heated plasmas show energy confinement times in excess of those predicted by empirical scaling expressions. Ion temperatures in excess of 2.0 keV have been measured, and power balance suggests that the power loss from the ions to the electrons may exceed the calculated classical input power to the ions.

  19. Local electron heating in the Io plasma torus associated with Io: the HISAKI observation

    NASA Astrophysics Data System (ADS)

    Tsuchiya, F.; Yoshioka, K.; Kimura, T.; Murakami, G.; Kagitani, M.; Yamazaki, A.; Kasaba, Y.; Sakanoi, T.; Yoshikawa, I.; Nozawa, H.

    2014-12-01

    Io-correlated brightness change in Io plasma torus (IPT) has been discovered by Voyager and show an evidence of local electron heating around Io. However, the amount of observation data is still limited to investigate its detail properties. In addition, the clear Io-correlated change has not been detected by EUVE and Cassini observations. Cause of the Io-correlated effect is still open issue. The HISAKI satellite was launched on Sep. 14, 2013 and started observation of IPT and Jovian aurora for more than two months since the end of Dec. 2013. EUV spectrograph onboard the HISAKI satellite covers wavelength range from 55 to 145 nm, a wide slit which had a field of view of 400 x 140 arc-second was chosen to measure radial distribution and time variation of IPT. Observation of IPT with HISAKI showed clear Io-correlated brightness change since the Voyager observation. The amplitude of the periodic variation associated with Io's orbital period was found. It also showed long-term variation during the HISAKI's observation period. Through the observation period, the amplitude was larger in the short wavelength than in long wavelength. The wavelength dependence suggests significant electron heating and/or hot electron production. The Io phase dependence shows that bright region is located just downstream of Io. These are evidence of local electron heating around/downstream of Io and consistent with the Voyager result. The brightness also depends on system-III longitude and has local maximum around 120 and 300 degrees. Based on an empirical model of IPT, electron density at Io also shows maxima around the same longitudes. This suggests that the electron heating process is related with plasma density at Io. Candidate mechanisms which are responsible for the electron heating will be discussed.

  20. Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary Nebulae

    E-print Network

    K. H. Tsui

    2008-03-04

    Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. These configurations are described by time self-similar dynamics, where space and time dependences of each physical variable are in separable form. Axisymmetric toroidal MHD plasma configuration is solved under the gravitational field of a central star of mass $M$. With an azimuthal magnetic field, this self-similar MHD model provides an equatorial structure in the form of an axisymmetric torus with nested and closed toroidal magnetic field lines. In the absence of an azimuthal magnetic field, this formulation models the basic features of bipolar planetary nebulae. The evolution function, which accounts for the time evolution of the system, has a bounded and an unbounded evolution track governed respectively by a negative and positive energy density constant $H$.

  1. Volcanic control of the Io atmosphere and neutral and plasma torus

    Microsoft Academic Search

    Aharon Eviatar

    1987-01-01

    Rate equations for the column density of Io's atmosphere and the number density of neutral atoms and ions in the torus have been formulated in terms of surface sublimation and venting of volcanic gases, sputtering efficiency, thermal escape, and the plasma processes that take place in the torus which included electron impact ionization, charge exchange, and transport. In the limit

  2. Magnetized plasma flow injection into tokamak and high-beta compact torus plasmas

    NASA Astrophysics Data System (ADS)

    Matsunaga, Hiroyuki; Komoriya, Yuuki; Tazawa, Hiroyasu; Asai, Tomohiko; Takahashi, Tsutomu; Steinhauer, Loren; Itagaki, Hirotomo; Onchi, Takumi; Hirose, Akira

    2010-11-01

    As an application of a magnetized coaxial plasma gun (MCPG), magnetic helicity injection via injection of a highly elongated compact torus (magnetized plasma flow: MPF) has been conducted on both tokamak and field-reversed configuration (FRC) plasmas. The injected plasmoid has significant amounts of helicity and particle contents and has been proposed as a fueling and a current drive method for various torus systems. In the FRC, MPF is expected to generate partially spherical tokamak like FRC equilibrium by injecting a significant amount of magnetic helicity. As a circumstantial evidence of the modified equilibrium, suppressed rotational instability with toroidal mode number n = 2. MPF injection experiments have also been applied to the STOR-M tokamak as a start-up and current drive method. Differences in the responses of targets especially relation with beta value and the self-organization feature will be studied.

  3. Microwave radiation measurements near the electron plasma frequency of the NASA Lewis Bumpy Torus plasma

    NASA Technical Reports Server (NTRS)

    Mallavarpu, R.; Roth, J. R.

    1978-01-01

    Microwave emission near the electron plasma frequency of the NASA Lewis Bumpy Torus plasma has been observed, and its relation to the average electron density and the dc toroidal magnetic field was examined. The emission was detected using a spectrum analyzer and a 50-ohm miniature coaxial probe. The radiation appeared as a broad amplitude peak that shifted in frequency as the plasma parameters were varied. The observed radiation scanned an average plasma density ranging from 20 billion to 800 billion per cu cm. A linear relation was observed between the density calculated from the emission frequency and the average plasma density measured with a microwave interferometer. With the aid of a relative density profile measurement of the plasma, it was determined that the emissions occurred from the outer periphery of the plasma.

  4. Pitch-angle diffusion by whistler mode waves near the Io plasma torus

    Microsoft Academic Search

    F. L. Scarf; F. V. Coroniti; D. A. Gurnett; W. S. Kurth

    1979-01-01

    As Voyager 1 traversed the inner radiation belt of Jupiter, wave-particle interactions involving energetic electrons and whistler mode turbulence were strongly affected by the presence of the Io plasma torus. Within the high density torus the resonant electron energy was low and the associated high index of refraction yielded high B-to-E ratios for the wave fields, leading to very strong

  5. Ion heating and containment in the NASA Lewis bumpy torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1974-01-01

    Experimental observations have been made during steady state operation of a torus experiment at input powers up to 150 kilowatts in deuterium and helium gas. The steady state ion heating method utilizes a modified Penning discharge operated in a bumpy torus confinement geometry. The bumpy torus plasma is acted upon by a combination of strong electric and magnetic fields. In a deuterium plasma, electron temperatures from 14 to 140 electron volts and ion kinetic temperatures from 160 to 1785 electron volts were observed. At least two distinct operating regimes exist, each of which is associated with a characteristic range of background gas pressure and electron temperature. Experimental data show that the average ion residence time in the plasma is virtually independent of magnetic field strength.

  6. Ion heating and containment in the NASA Lewis Bumpy Torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1974-01-01

    Experimental observations have been made during steady-state operation of the NASA Lewis Bumpy Torus experiment at input powers up to 150 kilowatts in deuterium and helium gas. A steady-state ion heating method utilizes a Modified Penning discharge operated in a bumpy torus confinement geometry. The bumpy torus plasma is acted upon by a combination of strong electric and magnetic fields. In a deuterium plasma, electron temperatures from 14 to 140 electron volts and ion kinetic temperatures from 160 to 1785 electron volts were observed. At least two distinct operating regimes exist, each of which is associated with a characteristic range of background gas pressure and electron temperature. Experimental data show that the average ion residence time (ionization time) in the plasma is virtually independent of the magnetic field strength.

  7. Characteristic of hot plasma in the Jovian magnetosphere: Results from the Voyager spacecraft

    Microsoft Academic Search

    S. M. Krimigis; J. F. Carbary; E. P. Keath; C. O. Bostrom; W. I. Axford; G. Gloeckler; L.J. Lanzerotti; T. P. Armstrong

    1981-01-01

    The low-energy charged particle (LECP) experiment on the Voyager 1 and 2 spacecraft made measurements of the intensity, energy spectra, angular distributions and composition of ions (30 keV< or approx. =E< or approx. = 150 MeV) and the electrons (14 keV< or approx. =E< or approx. =10 MeV) during encounters with the Jovian magnetosphere in 1979. Detailed analysis of the

  8. Response of the Io plasma torus to comet Shoemaker-Levy 9.

    PubMed

    McGrath, M A; Hall, D T; Matheson, P L; Weaver, H A; Trauger, J T; Smith, T E; Thomas, N; Gladstone, R; Schneider, N M; Harris, W M

    1995-03-01

    Spectroscopic and imaging observations of the Io plasma torus were made in June and July 1994 in conjunction with the encounter of periodic comet Shoemaker-Levy 9 with Jupiter. Characteristic emissions from sulfur and oxygen ions showed a decline of about 30 percent in the extreme ultraviolet and an increase of about 40 percent in the far ultraviolet relative to preimpact observations. Changes in the extreme ultraviolet may be indicative of small changes in the torus electron temperature as a result of quenching of electrons by dust associated with the comet passage. However, no new emission features indicative of fragment dust within the torus were detected. The characteristic torus morphology seen in ground-based imaging was typical of that observed in the past. PMID:7871429

  9. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis Bumpy Torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of the NASA Lewis Bumpy Torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power-law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of the potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied include the type of gas, the polarity of the midplane electrode rings (and hence the direction of the radial electric field), the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  10. Stratification-driven instabilities with bi-kappa distribution functions in the Io plasma torus

    Microsoft Academic Search

    N. André; K. M. Ferrière

    2008-01-01

    We extend our previous studies on plasma transport in the fast rotating magnetosphere of Jupiter. The present study uses a new kinetic Io plasma torus model in order to test the local stability criteria against stratification-driven low-frequency modes in this environment. Compared to the model used in our previous application, the new model introduces bi-kappa velocity distributions and plasma pressure

  11. Sounder stimulated D(sub n) resonances in Jupiter's Io plasma torus

    NASA Technical Reports Server (NTRS)

    Osherovich, V. A.; Benson, R. F.; Fainberg, J.; Stone, R. G.; Macdowall, R. J.

    1993-01-01

    On February 8, 1992, the Ulysses spacecraft passed through Jupiter's Io plasma torus, where rich spectra of narrow-band resonances were stimulated by the relaxation sounder of the Ulysses unified radio and plasma wave (URAP) instrument. Since the gyrofrequency f(sub g) is comparable to the plasma frequency f(sub p) in the Io torus, it was predicted that the general classification of stimulated ionospheric D(sub n) resonances, developed for 1 is less than or equal to f(sub p)/f(sub g) is less than or equal to 8 in the Earth's topside ionosphere, should apply in the Io torus as well as the Earth's magnetosphere (Osherovich, 1989). The URAP plasmagrams (sounder spectra) in the portions of the Io torus satisfying these plasma conditions are dominated by the D(sub n) resonances for frequencies below f(sub p). On most of these plasmagrams the f(sub p) resonance is also present, but it is seldom the dominant resonance. Neither upper hybrid nor nf(sub g) resonances have been found on these plasmagrams. The identification of D(sub n) resonances has allowed both the electron density and the magnetic field amplitude to be calculated. The derived densities on the outbound pass agree well with a Voyager model of Bagenal (1992). The derived magnetic field values are close to the Goddard Space Flight Center O(sub 6) magnetic field model.

  12. Resonant instability near the two-ion crossover frequency in the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Thorne, R. M.; Moses, J. J.

    1985-07-01

    Thorne and Scarf (1984) have presented evidence for the existence of intense low-frequency fluctuating electric fields in the Io plasma torus. Two distinct mechanisms have been proposed for this phenomenon, namely, ion cyclotron instability which occurs at intermediate latitude, and whistler instability near the equator. The present investigation is concerned with a quantitative appraisal of each of these mechanisms, taking into account an evaluation of the net convective growth rate of waves along ray paths which traverse the Io torus. Aspects of wave propagation near the crossover frequency are considered along with questions regarding the resonant interaction with energetic particles.

  13. Discovery of an Io-correlated energy source for Io's hot plasma torus

    NASA Astrophysics Data System (ADS)

    Sandel, B. R.; Broadfoot, A. L.

    1982-04-01

    Energy flowing into Io's hot plasma torus from a local-time correlated source and from an Io-related source are discussed, and a correlation of the brightness of the ansae of the torus with the apparent orbital phase of Io is reported. It is shown that the energy flows cause an azimuthal modulation of the brightness of the torus that is correlated with the position of Io, and the plasma downstream from Io is shown to be brighter in S III 685-A emission, which indicates a higher electron temperature. Differences in electron temperature inferred from spectral analyses account for all observed differences in brightness, implying that no change in the composition or density of the hot plasma occurs. The mechanism regulating the Io-related source is clearly distinct from the mechanism driving the local time source, although both draw on the same pool of energy, and the combination of the two sources is easily capable of supplying all the energy radiated by the torus.

  14. Plasma response to lithium-coated plasma-facing components in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Bell, M. G.; Kugel, H. W.; Kaita, R.; Zakharov, L. E.; Schneider, H.; Le Blanc, B. P.; Mansfield, D.; Bell, R. E.; Maingi, R.; Ding, S.; Kaye, S. M.; Paul, S. F.; Gerhardt, S. P.; Canik, J. M.; Hosea, J. C.; Taylor, G.; NSTX Research Team

    2009-12-01

    Experiments in the National Spherical Torus Experiment (NSTX) have shown beneficial effects on the performance of divertor plasmas as a result of applying lithium coatings on the graphite and carbon-fiber-composite plasma-facing components. These coatings have mostly been applied by a pair of lithium evaporators mounted at the top of the vacuum vessel which inject collimated streams of lithium vapor toward the lower divertor. In neutral beam injection (NBI)-heated deuterium H-mode plasmas run immediately after the application of lithium, performance modifications included decreases in the plasma density, particularly in the edge, and inductive flux consumption, and increases in the electron and ion temperatures and the energy confinement time. Reductions in the number and amplitude of edge-localized modes (ELMs) were observed, including complete ELM suppression for periods of up to 1.2 s, apparently as a result of altering the stability of the edge. However, in the plasmas where ELMs were suppressed, there was a significant secular increase in the effective ion charge Zeff and the radiated power as a result of increases in the carbon and medium-Z metallic impurities, although not of lithium itself which remained at a very low level in the plasma core, <0.1%. The impurity buildup could be inhibited by repetitively triggering ELMs with the application of brief pulses of an n = 3 radial field perturbation. The reduction in the edge density by lithium also inhibited parasitic losses through the scrape-off-layer of ICRF power coupled to the plasma, enabling the waves to heat electrons in the core of H-mode plasmas produced by NBI. Lithium has also been introduced by injecting a stream of chemically stabilized, fine lithium powder directly into the scrape-off-layer of NBI-heated plasmas. The lithium was ionized in the SOL and appeared to flow along the magnetic field to the divertor plates. This method of coating produced similar effects to the evaporated lithium but at lower amounts.

  15. The probability distributions of S/+/ gyrospeeds in the Io torus

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1982-01-01

    The first detailed thermal speed probability distribution for a Jovian plasma ion is presented. The distribution of heavy ion thermal speeds appears to be highly significant for an evaluation of the processes by which the particle and energy budgets of the Io plasma torus are maintained. Attention is given to the measurement, reduction, and analysis procedures which yield the reported probability distribution. A kinetic energy inventory of the Jovian plasma heavy ion component can be obtained from high-resolution, high-precision spectrophotometry of emission lines. The current S(+) study finds that detection of the line wings results in a mean energy (approximately 60 eV) which is higher by a factor of approximately 10 than is implied by the line core. This illustrates that a dispersive measurement may provide only a lower limit to the kinetic energy content.

  16. Modeling of Jovian Hectometric Radiation Source Locations: Ulysses Observations

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Reiner, M. J.

    1996-01-01

    The Unified Radio and Plasma Wave (URAP) experiment on Ulysses has provided unique high latitude measurements of Jovian hectometric radiation (HOM) during its encounter with Jupiter in February 1992. URAP was the first radio instrument in the Jovian environment with radio direction-finding capability, which was previously used to determine the HOM source locations in the Jovian magnetosphere. These initial source location determinations were based on several assumptions, including the neglect of refractive effects, which may be tested. We have, for the first time, combined the measured incident ray-direction at the spacecraft with a model magnetosphere to directly trace the rays back to the HOM source. We concentrate on the observations of HOM from high northern latitudes when Ulysses was at distances less than 15 R(sub j). The three- dimensional ray-tracing calculations presented here indicate that the HOM sources probably lie on L shells in the range 3 less than or approximately equal to L less than 7 (tilted dipole magnetic field model) consistent with previous determinations that ignored the effects of refraction. The ray-tracing results, however, indicate that wave refraction due to the Io torus and the magnetic field can significantly influence the precise source location. We show that constraints on the locations imposed by the gyroemission mechanism suggest that the lo torus density may have experienced temporal and/or spatial fluctuations during the Ulysses observations of HOM. Finally, in the cold plasma approximation we demonstrate that even if the emission were nearly linearly polarized near the source region, almost circular polarization will be observed at Ulysses, in agreement with observations.

  17. Jovian Seismology

    NASA Astrophysics Data System (ADS)

    Mosser, B.

    1996-09-01

    Seismic observations were performed immediately after the impacts of Shoemaker-Levy 9 fragments A and H with the mid-IR camera \\timmi\\ at the ESO 3.6-m telescope, and one week after the impacts with \\timmi, \\camiras\\ at the NOT and c10\\mu at the CFHT. These mid-IR cameras allowed us to monitor the atmospheric temperature over the full planetary disk, and to search for possible perturbations due to sound waves. The hodogram analysis has been unable to detect any seismic signature of the primary pressure waves crossing the planet within two hours following each impact (Mosser et al. 1996). This non-detection implies that the kinetic energy of impacts A and H was less than 2* 10(21) J, within the frame of the theoretical simulation (Lognonne et al. 1994). The error bar is as large as one order of magnitude. Pressure modes (resonant waves with periods in excess of 5.5 minutes, trapped in the Jovian cavity) were searched during the week following the impacts period. Even if the energy deposited by all the impacts was certainly too low to excite detectable modes, the 40-hour observation provided a unique time series for the monitoring of the Jovian normal modes. The main steps of the data reduction and analysis will be presented (centering of the IR images, decomposition of the Jovian thermal map in spherical harmonics...), as well as by-products (10-mu m maps of Jupiter...). Lognonne Ph., Mosser B., Dahlen F.} 1994. Excitation of Jovian seismic waves by the Shoemaker-Levy/9 cometary impact. Icarus 110, 180-195 Mosser B., et al. 1996. Impact seismology: a search for primary pressure waves following impacts A and H. Icarus 121, 331-340

  18. Study of plasma confinement in ELMO Bumpy Torus with a heavy-ion beam probe

    SciTech Connect

    Bieniosek, F. M.

    1981-01-01

    Plasma confinement in ELMO Bumpy Torus (EBT) is generally strongly dependent on an ambipolar electric field. Spatially resolved measurements of the resulting electric space potential phi/sub sp/ have been made in a single plasma cross section by the heavy-ion beam probe. This diagnostic injects a 4-60-keV beam of (usually) Cs/sup +/ ions into the plasma. Measurement of the energy of Cs/sup 2 +/ secondary ions leaving the plasma gives a continuous monitor of the local space potential. In addition, the total detected Cs/sup 2 +/ ion current is proportional to the product of the local electron density and the ionization rate, which, in turn, is a function of the electron temperature. This signal, nf(T/sub e/), is sensitive to all three electron distributions found in EBT - those of the cold surface plasma, the warm core plasma, and the hot electron ring.

  19. Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas

    SciTech Connect

    D.S. Darrow; S.S. Medley; A.L. Roquemore; W.W. Heidbrink; A. Alekseyev; F.E. Cecil; J. Egedal; V.Ya. Goloborod'ko; N.N. Gorelenkov; M. Isobe; S. Kaye; M. Miah; F. Paoletti; M.H. Redi; S.N. Reznik; A. Rosenberg; R. White; D. Wyatt; V.A. Yavorskij

    2002-10-15

    A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the {approx}25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong.

  20. Spherical torus plasma interactions with large-area liquid lithium surfaces in CDX-U

    Microsoft Academic Search

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; B. Jones; D. Hoffman; H. Kugel; J. Menard; T. Munsat; A. Post-Zwicker; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; G. Antar; R. Doerner; S. Luckhardt; R. Maingi; M. Maiorano; S. Smith

    2002-01-01

    The current drive experiment-upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail

  1. Spherical Torus Plasma Interactions with Large-area Liquid Lithium Surfaces in CDX-U

    Microsoft Academic Search

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; B. Jones; D. Hoffman; H. Kugel; J. Menard; T. Munsat; A. Post-Zwicker; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; G. Antar; R. Doerner; S. Luckhardt; R. Maingi; M. Maiorano; S. Smith

    2002-01-01

    The Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail

  2. Characteristics of the NASA Lewis bumpy-torus plasma generated with positive applied potentials

    NASA Technical Reports Server (NTRS)

    Roth, J. R.; Gerdin, G. A.; Richardson, R. W.

    1976-01-01

    Experimental observations were made during steady-state operation of a bumpy-torus plasma at input powers up to 150 kW in deuterium and helium gas and with positive potentials applied to the midplane electrodes. In this steady-state ion heating method a modified Penning discharge is operated such that the plasma is acted upon by a combination of strong electric and magnetic fields. Experimental investigation of a deuterium plasma revealed electron temperatures from 14 to 140 eV and ion kinetic temperatures from 160 to 1785 eV. At least two distinct modes of operation exist. Experimental data shows that the average ion residence time in the plasma is virtually independent of the magnetic field strength. Data was taken when all 12 anode rings were at high voltage, and in other symmetric configurations in which the toroidal plasma was generated by applying positive potentials to six anode rings, three anode rings, and a single anode ring.

  3. Unified Ideal Stability Limits for Advanced Tokamak and Spherical Torus Plasmas

    SciTech Connect

    J.E. Menard; M.G. Bell; R.E. Bell; D.A. Gates; S.M. Kaye; B.P. LeBlanc; S.A. Sabbagh; E.D. Fredrickson; S.C. Jardin; R. Maingi; J. Manickam; D. Mueller; M. Ono; F. Paoletti; Y.-K.M. Peng; V. Soukhanovskii; D. Stutman; E.J. Synakowski; the NSTX research team

    2003-02-06

    Ideal magnetohydrodynamic stability limits of shaped tokamak plasmas with high bootstrap fraction are systematically determined as a function of plasma aspect ratio. For plasmas with and without wall stabilization of external kink modes, the computed limits are well described by distinct and nearly invariant values of a normalized beta parameter utilizing the total magnetic field energy density inside the plasma. Stability limit data from the low aspect ratio National Spherical Torus Experiment is compared to these theoretical limits and indicates that ideal nonrotating plasma no-wall beta limits have been exceeded in regimes with sufficiently high cylindrical safety factor. These results could impact the choice of aspect ratio in future fusion power plants.

  4. In situ detection of interplanetary and Jovian nanodust with radio and plasma

    E-print Network

    Demoulin, Pascal

    the radio (Warwick et al., 1982) nor the plasma wave (Scarf et al., 1982) instrument was designed to do so on a number of spacecraft in various environments, using instruments that were generally not designed to do so

  5. Resistive magnetohydrodynamic simulations of helicity-injected startup plasmas in National Spherical Torus eXperiment

    SciTech Connect

    Hooper, E. B. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Sovinec, C. R. [Department of Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)] [Department of Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Raman, R. [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States)] [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Ebrahimi, F. [Department of Astrophysical Sciences, Princeton University, New Jersey 08544 (United States) [Department of Astrophysical Sciences, Princeton University, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Menard, J. E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2013-09-15

    The generation of helicity-injected startup plasmas in National Spherical Torus eXperiment (NSTX), including flux surface closure, is studied using resistive-magnetohydrodynamic simulations with plasma flows, currents, ohmic heating and anisotropic thermal conduction. An injection-voltage pulse shape is used that separates the injection and closure phases allowing elucidation of the physics. The formation of an X-point near the helicity-injection gap is triggered as the injector voltage drops to zero. Near the forming X-point, magnetic pressure due to toroidal field entrained in the E × B plasma flow from the helicity-injection gap drops, allowing resistive magnetic reconnection even though the total injected current is almost constant. Where appropriate, the simulations are compared with Transient Coaxial Helicity Injection experiments in the NSTX spherical tokamak, which have demonstrated the formation of a promising candidate for non-inductive startup plasmas [Raman et al., Phys. Rev. Lett. 90, 075005 (2003)].

  6. The proton concentration in the vicinity of the Io plasma torus

    NASA Technical Reports Server (NTRS)

    Tokar, R. L.; Gurnett, D. A.; Bagenal, F.

    1982-01-01

    Observations of lightning-generated whistlers conducted with the aid of the Voyager 1 plasma wave instrument during the March, 1979 encounter of Jupiter have been employed in numerous studies involving Jupiters's inner magnetosphere. In an investigation carried out by Tokar et al. (1982), the Voyager whistler observations were combined with heavy ion charged particle measurements in the Io torus to determine the light ion charge concentration along the whistler propagation paths. In the investigation, simple models were used for the plasma distribution along the propagation paths. In the present study, an improved model is used for the plasma distribution in the inner magnetosphere. The adopted model treats a plasma in diffusive equilibrium under the action of gravitational, centrifugal, and ambipolar electric field forces.

  7. Doppler line profiles measurement of the Jovian Lyman Alpha emission with OAO-C

    NASA Technical Reports Server (NTRS)

    Barker, E. S.; Cochran, W. D.; Smith, H. J.

    1982-01-01

    Observation of Jupiter made with the high resolution ultraviolet spectrometer of the Orbiting Astronomical Observatory copernicus in April and May, 1980, yield a Jovian Lyman alpha emission intensity of 7 + or 2.5 RR. This indicates a decrease by about a factor of two since the Voyager ultraviolet spectrometer measurements, nearly a year earlier. An unusually high column abundance of hydrogen atoms above the methane homopause at the Voyager epoch is indicated. Since the auroral charged particle bombardment of molecular hydrogen is expected to contribute significantly to the global population of the hydrogen atoms, it is suggested that at the time of the Voyager Jupiter encounter unusually high auroral activity existed, perhaps d to the high concentration of the Io plasma torus. The temporal variation of the Saturn lyman alpha emission, when contrasted with the Jovian data, reveals that the auroral processes are not nearly as important in determining the Saturn Lyman alpha intensity in the nonauroral region.

  8. New Horizons Exploration of the Jovian Magnetotail

    Microsoft Academic Search

    F. Bagenal; P. New Horizons; S. New Horizons

    2007-01-01

    A key issue of the jovian magnetosphere is how plasma is lost from the system down the magnetotail. Are large plasmoids ejected sporadically via explosive reconnection events (e.g. by analogy with Earth) or is there a steady \\

  9. Compact Torus Injection Development Leading to Core fueling, Start-up and Helicity Injection for ST plasmas

    Microsoft Academic Search

    M. Nagata; N. Fukumoto; Y. Kikuchi

    Several Compact Torus (CT) injection programs in Japan were aimed at developing the scientific basis for the central particle fuelling, efficient start-up, MHD dynamo control and helicity injection current drive for tokamak (JFT-2M), reversed-field pinch (TPE-RX), spherical torus (HIST) and helical (LHD) plasmas. So far, Canada conducted pioneering works in the CT injection into the TdeV tokamak (1). In the

  10. In situ detection of interplanetary and Jovian nanodust with radio and plasma

    E-print Network

    Demoulin, Pascal

    on a number of spacecraft in various environments, using instruments that were generally not designed to do so Voyager, despite the fact that neither the radio (Warwick et al., 1982) nor the plasma wave (Scarf et al., 1982) instrument was designed to do so. These pionneering re- sults opened the way to micro dust

  11. Probing the structure, composition, and dynamics of the Jovian plasma sheet with energetic particles

    Microsoft Academic Search

    Lara Suzon Waldrop

    2004-01-01

    Jupiter possesses the largest magnetosphere in the solar system through its unique combination of rapid planetary rotation, internal plasma source, and immense intrinsic planetary magnetic field. The nature of its interaction with the solar wind has long been an outstanding question in solar system physics, addressed recently by the unprecedented in situ observations of Jupiter's near- equatorial magnetosphere obtained by

  12. Characteristics of the NASA Lewis bumpy torus plasma generated with high positive or negative applied potentials

    NASA Technical Reports Server (NTRS)

    Roth, J. R.; Gerdin, G. A.

    1976-01-01

    The toroidal ring of plasma contained in the NASA Lewis bumpy-torus superconducting magnet facility may be biased to positive or negative potentials approaching 50 kilovolts by applying direct-current voltages of the respective polarity to 12 or fewer of the midplane electrode rings. The electric fields which are responsible for heating the ions by E/B drift then point radially outward or inward. The low-frequency fluctuations below the ion cyclotron frequency appeared to be dominated by rotating spokes.

  13. Plasma IMS Composition Measurements for Europa, Ganymede, and the Jovian System

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.; Cooper, J. F.; Hartle, R. E.; Paterson, W. R.; Christian, E. R.; Lipatov, A. S.; Mahaffy, P R.; Paschalidis, N.; Sarantos, M.; Coplan, M. A.; Cassidy, T. A.; Wurz, P.

    2011-01-01

    NASA and ESA are now planning a reduced version of the joint Europa Jupiter System Mission (EJSM), potentially including a radically descoped Jupiter Europa Orbiter (JEO) but still with magnetometer and plasma instruments. Similar field and plasma instrumentation would also reside on ESA's Jupiter Ganymede Orbiter (JGO), which conceivably could carry out multiple flybys of Europa before entering orbit at Ganymede. We are developing the 3D Ion Mass Spectrometer (IMS) designed to measure both major and minor ion species within the high radiation environment of Jupiter's magnetosphere and the icy Galilean moons. The IMS covers the energy range from 10 eV to 30 keY, wide field-of-view (FOV) capability and 10-60 sec time resolution for major ions. This instrument has two main goals: 1) measure the plasma interaction between Europa and Jupiter's magnetosphere and 2) infer the global surface composition to trace elemental and significant isotopic levels; these goals are also applicable for in-situ measurements at Ganymede and Callisto, and remotely everywhere via the iogenic plasma for 10. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa's sub-surface ocean, while the second goal gives information about transfer of material between the Galilean moons, e.g. mainly from 10 to the other moons, and further allows detection of oceanic materials emergent to the moon surfaces from subsurface layers putatively including salt water oceans. Outgassed exospheric materials are probed by the IMS by measuring pickup ions accelerated up to spacecraft altitudes of approximately 100-200 km in electric fields extending through the local magnetospheric environment and moon exosphere to the surface. Our 3D hybrid kinetic model of the moon-magnetosphere interaction is used to construct a global model of electric and magnetic fields for tracing of pickup ion trajectories back to the sources at approximate surface resolution of 100 km. We show that Europa's exospheric ionosphere is dominated by pickup ions with energies of 100-1000 eV. We also expect field aligned polar ion outflows driven by ionospheric electrons via the polarization electric field at Europa; the IMS will observe such outflows and thus sample the ionosphere below spacecraft orbit altitude approximately 100 km. Based on previous Ganymede studies, we also comment on IMS applications to a Ganymede orbiter. The IMS and the Europa interaction model are respectively being developed with support from NASA's Astrobiology Instrument Development (ASTID) and Outer Planets Research (OPR) programs.

  14. Plasma IMS Composition Measurements for Europa, Ganymede, and the Jovian Systems

    NASA Technical Reports Server (NTRS)

    Sittler, E.; Cooper, J.; Hartle, R.; Paterson ,W.; Christian, E.; Mahaffy, P.; Paschalidis, N.; Lipatov, A.; Sarantos, M.; Coplan, M.; Cassidy, T.; Wurz, P.

    2011-01-01

    NASA and ESA are now planning a reduced version of the joint Europa Jupiter System Mission (EJSM), potentially including a radically descoped Jupiter Europa Orbiter (JEO) but still with magnetometer and plasma instruments. Similar field and plasma instrumentation would also reside on ESA's Jupiter Ganymede Orbiter (JGO), which conceivably could carry out multiple flybys of Europa before entering orbit at Ganymede. We are developing the 3D Ion Mass Spectrometer (IMS) designed to measure both major and minor ion species within the high radiation environment of Jupiter s magnetosphere and the icy Galilean moons. The IMS covers the energy range from 10 eV to 30 keV, wide field-ofview (FOV) capability and 10-60 sec time resolution for major ions. This instrument has two main goals: 1) measure the plasma interaction between Europa and Jupiter s magnetosphere and 2) infer the global surface composition to trace elemental and significant isotopic levels; these goals are also applicable for in-situ measurements at Ganymede and Callisto, and remotely everywhere via the iogenic plasma for Io. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa's sub-surface ocean, while the second goal gives information about transfer of material between the Galilean moons, e.g. mainly from Io to the other moons, and further allows detection of oceanic materials emergent to the moon surfaces from subsurface layers putatively including salt water oceans. Outgassed exospheric materials are probed by the IMS by measuring pickup ions accelerated up to spacecraft altitudes of approximately 100-200 km in electric fields extending through the local magnetospheric environment and moon exosphere to the surface. Our 3D hybrid kinetic model of the moon-magnetosphere interaction is used to construct a global model of electric and magnetic fields for tracing of pickup ion trajectories back to the sources at approximate surface resolution of 100 km. We show that Europa's exospheric ionosphere is dominated by pickup ions with energies of 100-1000 eV. We also expect field aligned polar ion outflows driven by ionospheric electrons via the polarization electric field at Europa; the IMS will observe such outflows and thus sample the ionosphere below spacecraft orbit altitude approximately 100 km. Based on previous Ganymede studies, we also comment on IMS applications to a Ganymede orbiter. The IMS and the Europa interaction model are respectively being developed with support from NASA's Astrobiology Instrument Development (ASTID) and Outer Planets Research (OPR) programs.

  15. Edge plasma characteristics in the helicity injected torus (HIT-II) spherical tokamak

    NASA Astrophysics Data System (ADS)

    Jain, K. K.; Redd, A. J.; Jarboe, T. R.; Nelson, B. A.; HIT Team

    2003-07-01

    The helicity injected torus (HIT-II) device is a spherical tokamak capable of both inductive (Ohmic) and co-axial helicity injection (CHI) current drive. The HIT-II plasma edge, in both Ohmic and CHI discharges, has been characterized using a triple Langmuir probe. An Ohmic discharge develops in two phases, a slide-away phase followed by a normal Ohmic discharge. During the normal Ohmic discharge, the floating potential is negative, just as in a conventional large-aspect-ratio tokamak. The plasma density increases sharply from the plasma edge into the centre. The auto-power spectrum of Ohmic plasma edge fluctuations shows a nearly constant auto-power at low frequencies, with auto-power decreasing at higher frequencies, similar to observations in conventional large-aspect-ratio tokamaks. In HIT-II CHI discharges, the magnetic field lines at the plasma edge are clearly connected to the injector electrodes, as expected. However, the time-evolution of the floating potential in the core plasma is significantly different from that of the edge, which may indicate a decoupling of the core plasma from the CHI electrodes. Finally, the fluctuations at the edge of high-performance CHI discharges exhibit a coherent oscillation at a frequency similar to that of the observed n = 1 mode.

  16. Low energy ion distribution measurements in Madison Symmetric Torus plasmas J. B. Titus, E. D. Mezonlin, and J. A. Johnson III

    E-print Network

    Wisconsin at Madison, University of

    Low energy ion distribution measurements in Madison Symmetric Torus plasmas J. B. Titus, E. D.104.166.176 On: Fri, 20 Jun 2014 19:05:42 #12;Low energy ion distribution measurements in Madison Symmetric Torus, Florida 32310, USA 2 Pyramid Plasmas LLC, Lawrenceville, Georgia 30043, USA (Received 8 May 2014; accepted

  17. Radial Variations in the Io Plasma Torus during the Cassini Era

    NASA Technical Reports Server (NTRS)

    Delamere, P. A.; Bagenal, F.; Steffl, A.

    2005-01-01

    A radial scan through the midnight sector of the Io plasma torus was made by the Cassini Ultraviolet Imaging Spectrograph on 14 January 2001, shortly after closest approach to Jupiter. From these data, Steffl et al. (2004a) derived electron temperature, plasma composition (ion mixing ratios), and electron column density as a function of radius from L = 6 to 0 as well as the total luminosity. We have advanced our homogeneous model of torus physical chemistry (Delamere and Bagenal, 2003) to include latitudinal and radial variations in a manner similar to the two-dimensional model by Schreier et al. (1998). The model variables include: (1) neutral source rate, (2) radial transport coefficient, (3) the hot electron fraction, (4) hot electron temperature, and (5) the neutral O/S ratio. The radial variation of parameters 1-4 are described by simple power laws, making a total of nine parameters. We have explored the sensitivity of the model results to variations in these parameters and compared the best fit with previous Voyager era models (schreier et al., 1998), galileo data (Crary et al., 1998), and Cassini observations (steffl et al., 2004a). We find that radial variations during the Cassini era are consistent with a neutral source rate of 700-1200 kg/s, an integrated transport time from L = 6 to 9 of 100-200 days, and that the core electron temperature is largely determined by a spatially and temporally varying superthermal electron population.

  18. Ground-based observations of comets, the Jupiter plasma Torus, and Io

    NASA Technical Reports Server (NTRS)

    Scherb, Frank; Roesler, Fred L.

    1991-01-01

    Aspects of cometary and magnetospheric physics were investigated by means of ground-based astronomical spectroscopy. High-throughput, dual-etalon Fabry-Perot spectrometers were used to obtain very high resolution spectra of atomic, molecular, and ionic emission lines from the diffuse gases and plasmas associated with comets and the Jupiter plasma torus. The Fabry-Perot spectrometers were also used with a charge coupled device (CCD) camera to obtain images of these extended emission sources in individual spectral lines at high spectral resolution. A new program using the McMath solar-stellar spectrograph to observe emission lines from Io was recently initiated. The McMath spectrograph has a high resolution mode which allows the detection of narrow, relatively faint emission lines superimposed on Io's reflected solar spectrum.

  19. Initial characterization of electron cyclotron heated plasmas in the Columbia Non-Neutral Torus

    NASA Astrophysics Data System (ADS)

    Hammond, Kenneth; Volpe, Francesco; Lazerson, Samuel

    2014-10-01

    The Columbia Non-Neutral Torus (CNT) is a stellarator at Columbia University recently modified for the study of quasi-neutral plasmas heated by 2.45 GHz electron cyclotron waves. Using a simple configuration of four circular planar coils, it generates magnetic surfaces with the lowest aspect ratios (1.9-2.7) ever attained by a stellarator. The low magnetic field (0.09 T), combined with the possibility of electron Bernstein wave heating above the cutoff density, could make CNT suitable for research of magnetohydrodynamic equilibrium and stability at high beta. Additional plans for future work include novel microwave and magnetic diagnostics, heating with electron cyclotron and helicon waves, and error field studies. Here we present an experimental characterization of the parameters of CNT's first microwave-heated plasmas. We present Langmuir probe measurements of temperature and density profiles, fast camera images, and equilibrium reconstructions computed by the VMEC code.

  20. Plasma Shape Control on the National Spherical Torus Experiment (NSTX) using Real-time Equilibrium Reconstruction

    SciTech Connect

    D.A. Gates; J.R. Ferron; M. Bell; T. Gibney; R. Johnson; R.J. Marsala; D. Mastrovito; J.E. Menard; D. Mueller; B. Penaflor; S.A. Sabbagh; T. Stevenson

    2005-04-15

    Plasma shape control using real-time equilibrium reconstruction has been implemented on the National Spherical Torus Experiment (NSTX). The rtEFIT code originally developed for use on DIII-D was adapted for use on NSTX. The real-time equilibria provide calculations of the flux at points on the plasma boundary, which is used as input to a shape control algorithm known as isoflux control. The flux at the desired boundary location is compared to a reference flux value, and this flux error is used as the basic feedback quantity for the poloidal-field coils on NSTX. The hardware that comprises the control system is described, as well as the software infrastructure. Examples of precise boundary control are also presented.

  1. Observation of instability-induced current redistribution in a spherical-torus plasma.

    PubMed

    Menard, J E; Bell, R E; Gates, D A; Kaye, S M; LeBlanc, B P; Levinton, F M; Medley, S S; Sabbagh, S A; Stutman, D; Tritz, K; Yuh, H

    2006-09-01

    A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER. PMID:17026371

  2. Observation of Instability-Induced Current Redistribution in a Spherical-Torus Plasma

    NASA Astrophysics Data System (ADS)

    Menard, J. E.; Bell, R. E.; Gates, D. A.; Kaye, S. M.; Leblanc, B. P.; Levinton, F. M.; Medley, S. S.; Sabbagh, S. A.; Stutman, D.; Tritz, K.; Yuh, H.

    2006-09-01

    A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

  3. Jovian Lightning

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The knots of light which have been circled in yellow in this false color picture probably represent lightning in Jupiter's atmosphere. The picture was taken at 5 hours 3 minutes Universal Time on November 9, 1996 through the clear filter of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft. The largest of the circled spots is over 500 kilometers across, comparable in size to the lightning events seen by NASA's Voyager 2 spacecraft in 1979, but much larger than the single lightning flashes seen by Voyager 1. Thus each of the larger circled spots represents either multiple flashes within a large lightning storm, or a single flash illuminating a much higher cloud.

    The planetocentric latitude lines imposed on this image indicate that the circled events lie at about 44 degrees North latitude, just below a westward moving jet at 46 degrees North. Almost all of the Jovian lightning seen by Voyager similarly occurred near the latitude of a westward moving jet. Moreover, the circled events occurred in Jupiter's most atmospherically active high latitude region (between 36 and 46 degrees North), which is one of the zones where lightning is most likely.

    In order to detect lightning the camera was scanned horizontally across the darkside of Jupiter, starting just inside the eastern edge of the planet and ending just inside its western edge. The scanning motion was employed both to cover the largest possible longitude range, and to help separate lightning strokes emanating from the same storm.

    Several of the circled spots are relatively elongated in the east-west direction, perhaps due to the scanning motion of the camera (and/or to a foreshortening in the north-south direction caused by the curvature of the planet). The circled events appear well separated in space, and any apparent separation in latitude is real. Because of the scanning motion of the camera, however, these events may not have been truly separated in longitude. It is even possible that they all came from the same localized storm, and were separated principally in time.

    Diffuse light covers much of this picture, and is particularly bright in the bottom righthand corner. Some of this emission may be moonlit clouds, but much of it is likely sunlight scattered into the camera by the atmosphere along Jupiter's edge.

    At the time of this observation Galileo was in Jupiter's shadow, and located about 2.3 million kilometers (about 32 Jovian radii) from the planet.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  4. Spherical torus fusion reactor

    Microsoft Academic Search

    Martin Peng; Y. K. M

    1985-01-01

    The object of this invention is to provide a compact torus fusion reactor with dramatic simplification of plasma confinement design. Another object of this invention is to provide a compact torus fusion reactor with low magnetic field and small aspect ratio stable plasma confinement. In accordance with the principles of this invention there is provided a compact toroidal-type plasma confinement

  5. A coordinated X-ray and EUV study of the Jovian aurora

    NASA Astrophysics Data System (ADS)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randall; Badman, Sarah; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen; Rodiger, Elke; Tsuchiya, Fuminori; Yamazaki, Atsushi; Yoshikawa, Ichiro; Yoshioka, Kazuo

    2015-04-01

    We present results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument and twice by XMM-Newton for roughly 12 hours per observation. The goal of this campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  6. Surface Treatment of a Lithium Limiter for Spherical Torus Plasma Experiments

    SciTech Connect

    Kaita, R.; Majeski, R.; Doerner, R.; Antar, G.; Timberlake, J.; Spaleta, J.; Hoffman, D.; Jones, B.; Munsat, T.; Kugel, H.; Taylor, G.; Stutman, D.; Soukhanovskii, V.; Maingi, R.; Molesa, S.; Efthimion, P.; Menard, J.; Finkenthal, M.; Luckhardt, S.

    2001-03-20

    The concept of a flowing lithium first wall for a fusion reactor may lead to a significant advance in reactor design, since it could virtually eliminate the concerns with power density and erosion, tritium retention, and cooling associated with solid walls. As part of investigations to determine the feasibility of this approach, plasma interaction questions in a toroidal plasma geometry are being addressed in the Current Drive eXperiment-Upgrade (CDX-U) spherical torus (ST). The first experiments involved a toroidally local lithium limiter (L3). Measurements of pumpout rates indicated that deuterium pumping was greater for the L3 compared to conventional boron carbide limiters. The difference in the pumpout rates between the two limiter types decreased with plasma exposure, but argon glow discharge cleaning was able to restore the pumping effectiveness of the L3. At no point, however, was the extremely low recycling regime reported in previous lithium experiments achieved. This may be due to the much larger lithium surfaces that were exposed to the plasma in the earlier work. The possibility will be studied in the next set of CDX-U experiments, which are to be conducted with a large area, fully toroidal lithium limiter.

  7. Effect of plasma shaping on performance in the National Spherical Torus Experimenta)

    NASA Astrophysics Data System (ADS)

    Gates, D. A.; Maingi, R.; Menard, J.; Kaye, S.; Sabbagh, S. A.; Taylor, G.; Wilson, J. R.; Bell, M. G.; Bell, R. E.; Bernabei, S.; Bialek, J.; Biewer, T.; Blanchard, W.; Boedo, J.; Bush, C.; Carter, M. D.; Choe, W.; Crocker, N.; Darrow, D. S.; Davis, W.; Delgado-Aparicio, L.; Diem, S.; Ferron, J.; Field, A.; Foley, J.; Fredrickson, E. D.; Harvey, R.; Hatcher, R. E.; Heidbrink, W.; Hill, K.; Hosea, J. C.; Jarboe, T. R.; Johnson, D. W.; Kaita, R.; Kessel, C.; Kubota, S.; Kugel, H. W.; Lawson, J.; LeBlanc, B. P.; Lee, K. C.; Levinton, F.; Manickam, J.; Maqueda, R.; Marsala, R.; Mastrovito, D.; Mau, T. K.; Medley, S. S.; Meyer, H.; Mikkelsen, D. R.; Mueller, D.; Munsat, T.; Nelson, B. A.; Neumeyer, C.; Nishino, N.; Ono, M.; Park, H.; Park, W.; Paul, S.; Peebles, W.; Peng, M.; Phillips, C.; Pigarov, A.; Pinsker, R.; Ram, A.; Ramakrishnan, S.; Raman, R.; Rasmussen, D.; Redi, M.; Rensink, M.; Rewoldt, G.; Robinson, J.; Roney, P.; Roquemore, L.; Ruskov, E.; Ryan, P.; Schneider, H.; Skinner, C. H.; Smith, D. R.; Sontag, A.; Soukhanovskii, V.; Stevenson, T.; Stotler, D.; Stratton, B.; Stutman, D.; Swain, D.; Synakowski, E.; Takase, Y.; Tritz, K.; Halle, A. von; Wade, M.; White, R.; Wilgen, J.; Williams, M.; Zhu, W.; Zweben, S. J.; Akers, R.; Beiersdorfer, P.; Betti, R.; Bigelow, T.

    2006-05-01

    The National Spherical Torus Experiment (NSTX) has explored the effects of shaping on plasma performance as determined by many diverse topics including the stability of global magnetohydrodynamic (MHD) modes (e.g., ideal external kinks and resistive wall modes), edge localized modes (ELMs), bootstrap current drive, divertor flux expansion, and heat transport. Improved shaping capability has been crucial to achieving ?t˜40%. Precise plasma shape control has been achieved on NSTX using real-time equilibrium reconstruction. NSTX has simultaneously achieved elongation ? ˜2.8 and triangularity ? ˜0.8. Ideal MHD theory predicts increased stability at high values of shaping factor S ?q95Ip/(aBt), which has been observed at large values of the S ˜37[MA/(m•T)] on NSTX. The behavior of ELMs is observed to depend on plasma shape. A description of the ELM regimes attained as shape is varied will be presented. Increased shaping is predicted to increase the bootstrap fraction at fixed Ip. The achievement of strong shaping has enabled operation with 1s pulses with Ip=1MA, and for 1.6s for Ip=700kA. Analysis of the noninductive current fraction as well as empirical analysis of the achievable plasma pulse length as elongation is varied will be presented. Data are presented showing a reduction in peak divertor heat load due to increasing in flux expansion.

  8. Oscillator strengths for S I, S II, and S III. [in Io plasma torus

    NASA Technical Reports Server (NTRS)

    Ho, Y. K.; Henry, Ronald J. W.

    1987-01-01

    A series of calculations for atomic data of various sulfur and oxygen ions is examined. Recent observations of the Io plasma torus obtained with the Voyager UV Spectrometer, the IUE satellite short wavelength spectrograph, and the rocket-borne faint object telescope are discussed. The calculation of oscillator strengths for S II, the P I sequence, S I, and S III in terms of configuration interaction effects is described. The derivation of orbital wave functions is considered. The use of the close coupling method to estimate collision strengths is studied. The accuracy of these calculations depends on: (1) the number of states used in the close coupling expansion; (2) resonance contributions to the thermally averaged collision strength; and (3) the quality of the target state wave functions. Tables of the derived oscillator strengths are presented.

  9. Rocket FUV Observations of the Io Plasma Torus During the Shoemaker-Levy/9 Impacts

    NASA Technical Reports Server (NTRS)

    Stern, S. A.; Slater, D.; Cash, W.; Wilkinson, E.; Green, J.; Gladstone, R.

    1995-01-01

    We observed the Io torus from 820-1140 A on universal time (UT) 20.25 July 1994 from a sounding rocket telescope/spectrograph. These observations serve as only the fourth published spectrum of the torus in this wavelength range, and the only far ultraviolet (FUV) data documenting the state of the torus during the Shoemaker Levy 9 Impacts.

  10. Long Pulse High Performance Plasma Scenario Development for the National Spherical Torus Experiment

    SciTech Connect

    Kessel, C.E.; Bell, R.E.; Bell, M.G.; Gates, D.A.; Harvey, R.W.

    2006-01-01

    The National Spherical Torus Experiment [Ono et al., Nucl. Fusion, 44, 452 (2004)] is targeting long pulse high performance, noninductive sustained operations at low aspect ratio, and the demonstration of nonsolenoidal startup and current rampup. The modeling of these plasmas provides a framework for experimental planning and identifies the tools to access these regimes. Simulations based on neutral beam injection (NBI)-heated plasmas are made to understand the impact of various modifications and identify the requirements for (1) high elongation and triangularity, (2) density control to optimize the current drive, (3) plasma rotation and/or feedback stabilization to operate above the no-wall limit, and (4) electron Bernstein waves (EBW) for off-axis heating/current drive (H/CD). Integrated scenarios are constructed to provide the transport evolution and H/CD source modeling, supported by rf and stability analyses. Important factors include the energy confinement, Zeff, early heating/H mode, broadening of the NBI-driven current profile, and maintaining q(0) and qmin>1.0. Simulations show that noninductive sustained plasmas can be reached at IP=800 kA, BT=0.5 T, 2.5, N5, 15%, fNI=92%, and q(0)>1.0 with NBI H/CD, density control, and similar global energy confinement to experiments. The noninductive sustained high plasmas can be reached at IP=1.0 MA, BT=0.35 T, 2.5, N9, 43%, fNI=100%, and q(0)>1.5 with NBI H/CD and 3.0 MW of EBW H/CD, density control, and 25% higher global energy confinement than experiments. A scenario for nonsolenoidal plasma current rampup is developed using high harmonic fast wave H/CD in the early low IP and low Te phase, followed by NBI H/CD to continue the current ramp, reaching a maximum of 480 kA after 3.4 s.

  11. Long pulse high performance plasma scenario development for the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Kessel, C. E.; Bell, R. E.; Bell, M. G.; Gates, D. A.; Kaye, S. M.; LeBlanc, B. P.; Menard, J. E.; Phillips, C. K.; Synakowski, E. J.; Taylor, G.; Wilson, R.; Harvey, R. W.; Mau, T. K.; Ryan, P. M.; Sabbagh, S. A.

    2006-05-01

    The National Spherical Torus Experiment [Ono et al., Nucl. Fusion, 44, 452 (2004)] is targeting long pulse high performance, noninductive sustained operations at low aspect ratio, and the demonstration of nonsolenoidal startup and current rampup. The modeling of these plasmas provides a framework for experimental planning and identifies the tools to access these regimes. Simulations based on neutral beam injection (NBI)-heated plasmas are made to understand the impact of various modifications and identify the requirements for (1) high elongation and triangularity, (2) density control to optimize the current drive, (3) plasma rotation and/or feedback stabilization to operate above the no-wall ? limit, and (4) electron Bernstein waves (EBW) for off-axis heating/current drive (H/CD). Integrated scenarios are constructed to provide the transport evolution and H/CD source modeling, supported by rf and stability analyses. Important factors include the energy confinement, Zeff, early heating/H mode, broadening of the NBI-driven current profile, and maintaining q(0) and qmin>1.0. Simulations show that noninductive sustained plasmas can be reached at IP=800 kA, BT=0.5 T, ??2.5, ?N?5, ??15%, fNI=92%, and q(0)>1.0 with NBI H/CD, density control, and similar global energy confinement to experiments. The noninductive sustained high ? plasmas can be reached at IP=1.0 MA, BT=0.35 T, ??2.5, ?N?9, ??43%, fNI=100%, and q(0)>1.5 with NBI H/CD and 3.0 MW of EBW H/CD, density control, and 25% higher global energy confinement than experiments. A scenario for nonsolenoidal plasma current rampup is developed using high harmonic fast wave H/CD in the early low IP and low Te phase, followed by NBI H/CD to continue the current ramp, reaching a maximum of 480 kA after 3.4 s.

  12. Progress towards high performance plasmas in the National Spherical Torus Experiment (NSTX)

    SciTech Connect

    Kaye, S. M.; Bell, M. G.; Bell, R. E.; Bernabei, S; Bialek, J.; Biewer, T.; Blanchard, W.; Boedo, J.; Bush, C.; Carter, M. D.; Choe, W.; Crocker, N.; Darrow, D. S.; Davis, W.; Delgado-Aparicio, L.; Diem, S.; Ferron, J.; Field, A.; Foley, J.; Fredrickson, E. D.; Gates, D. A.; Gibney, T.; Harvey, R.; Hatcher, R. E.; Heidbrink, W.; Hill, K.; Hosea, J. C.; Jarboe, T. R.; Johnson, D. W.; Kaita, R.; Kessel, C.; Kubota, S.; Kugel, H. W.; Lawson, J.; LeBlanc, B. P.; Lee, K. C.; Levinton, F.; Maingi, R.; Manickam, J.; Maqueda, R.; Marsala, R.; Mastrovito, D.; Mau, T. K.; Medley, S. S.; Menard, J.; Meyer, H.; Mikkelsen, D. R.; Mueller, D.; Munsat, T.; Nelson, B. A.; Neumeyer, C.; Nishino, N.; Ono, M.; Park, H.; Park, W.; Paul, S.; Peebles, T.; Peng, M.; Phillips, C.; Pigarov, A.; Pinsker, R.; Ram, A.; Ramakrishnan, S.; Raman, R.; Rasmussen, D.; Redi, M.; Rensink, M.; Rewoldt, G; Robinson, J.; Roney, P.; Roquemore, A. L.; Ruskov, E; Ryan, P.; Sabbagh, S. A.; Schneider, H.; Skinner, C. H.; Smith, D. R.; Sontag, A.; Soukhanovskii, V.; Stevenson, T.; Stotler, D.; Stratton, B.; Stutman, D.; Swain, D.; Synakowski, E.; Takase, Y.; Taylor, G.; Tritz, K.; Halle, A. von; Wade, M.; White, R.; Wilgen, J.; Williams, M.; Wilson, J. R.; Zhu, W.; Zweben, S. J.; Akers, R.; Beiersdorfer, P.; Betti, R.; Bigelow, T.; Bitter, M.; Bonoli, P.; Bourdelle, C.; Chang, C. S.; Chrzanowski, J.; Domier, C.; Dudek, L.; Efthimion, P. C.; Finkenthal, M.; Fredd, E.; Fu, G. Y.; Glasser, A.; Goldston, R. J.; Greenough, N. L.; Grisham, L. R.; Gorelenkov, N.; Guazzotto, L.; Hawryluk, R. J.; Hogan, J.; Houlberg, W.; Humphreys, D.; Jaeger, F.; Kalish, M.; Krasheninnikov, S.; Lao, L. L.; Lawrence, J.; Leuer, J.; Liu, D.; Luhmann, N. C.; Mazzucato, E.; Oliaro, G.; Pacella, D.; Parsells, R.; Schaffer, M.; Semenov, I.; Shaing, K. C.; Shapiro, M. A.; Shinohara, K.; Sichta, P.; Tang, X.; Vero, R.; Walker, D.; Wampler, W.

    2005-10-01

    The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high ?T in order to advance the spherical torus (ST) concept. In order to do this, NSTX utilizes up to 7.5 MW of neutral beam injection, up to 6 MW of high harmonic fast waves (HHFWs), and it operates with plasma currents up to 1.5 MA and elongations of up to 2.6 at a toroidal field up to 0.45 T. New facility, and diagnostic and modeling capabilities developed over the past two years have enabled the NSTX research team to make significant progress towards establishing this physics basis for future ST devices. Improvements in plasma control have led to more routine operation at high elongation and high ?T (up to ~40%) lasting for many energy confinement times. ?T can be limited by either internal or external modes. The installation of an active error field (EF) correction coil pair has expanded the operating regime at low density and has allowed for initial resonant EF amplification experiments. The determination of the confinement and transport properties of NSTX plasmas has benefited greatly from the implementation of higher spatial resolution kinetic diagnostics. The parametric variation of confinement is similar to that at conventional aspect ratio but with values enhanced relative to those determined from conventional aspect ratio scalings and with a ?T dependence. The transport is highly dependent on details of both the flow and magnetic shear. Core turbulence was measured for the first time in an ST through correlation reflectometry. Non-inductive start-up has been explored using PF-only and transient co-axial helicity injection techniques, resulting in up to 140 kA of toroidal current generated by the latter technique. Calculated bootstrap and beam-driven currents have sustained up to 60% of the flat-top plasma current in NBI discharges. Studies of HHFW absorption have indicated parametric decay of the wave and associated edge thermal ion heating. Energetic particle modes, most notably toroidal Alfven eigenmodes and fishbone-like modes result in fast particle losses, and these instabilities may affect fast ion confinement on devices such as ITER. Finally, a variety of techniques has been developed for fueling and power and particle control.

  13. Progress towards high performance plasmas in the National Spherical Torus Experiment (NSTX)

    SciTech Connect

    Kaye, S. [Princeton Plasma Physics Laboratory (PPPL); Peng, Yueng Kay Martin [ORNL

    2005-01-01

    The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high T in order to advance the spherical torus (ST) concept. In order to do this, NSTX utilizes up to 7.5MW of neutral beam injection, up to 6MW of high harmonic fast waves (HHFWs), and it operates with plasma currents up to 1.5MA and elongations of up to 2.6 at a toroidal field up to 0.45 T. New facility, and diagnostic and modelling capabilities developed over the past two years have enabled the NSTX research team to make significant progress towards establishing this physics basis for future ST devices. Improvements in plasma control have led to more routine operation at high elongation and high T (up to 40%) lasting for many energy confinement times. T can be limited by either internal or external modes. The installation of an active error field (EF) correction coil pair has expanded the operating regime at low density and has allowed for initial resonant EF amplification experiments. The determination of the confinement and transport properties of NSTX plasmas has benefitted greatly from the implementation of higher spatial resolution kinetic diagnostics. The parametric variation of confinement is similar to that at conventional aspect ratio but with values enhanced relative to those determined from conventional aspect ratio scalings and with a BT dependence. The transport is highly dependent on details of both the flow and magnetic shear. Core turbulence was measured for the first time in an ST through correlation reflectometry. Non-inductive start-up has been explored using PF-only and transient co-axial helicity injection techniques, resulting in up to 140 kA of toroidal current generated by the latter technique. Calculated bootstrap and beam-driven currents have sustained up to 60% of the flat-top plasma current in NBI discharges. Studies of HHFW absorption have indicated parametric decay of the wave and associated edge thermal ion heating. Energetic particle modes, most notably toroidal Alfv en eigenmodes and fishbone-like modes result in fast particle losses, and these instabilities may affect fast ion confinement on devices such as ITER. Finally, a variety of techniques has been developed for fuelling and power and particle control.

  14. Progress towards high performance plasmas in the National Spherical Torus Experiment (NSTX)

    NASA Astrophysics Data System (ADS)

    Kaye, S. M.; Bell, M. G.; Bell, R. E.; Bernabei, S.; Bialek, J.; Biewer, T.; Blanchard, W.; Boedo, J.; Bush, C.; Carter, M. D.; Choe, W.; Crocker, N.; Darrow, D. S.; Davis, W.; Delgado-Aparicio, L.; Diem, S.; Ferron, J.; Field, A.; Foley, J.; Fredrickson, E. D.; Gates, D. A.; Gibney, T.; Harvey, R.; Hatcher, R. E.; Heidbrink, W.; Hill, K.; Hosea, J. C.; Jarboe, T. R.; Johnson, D. W.; Kaita, R.; Kessel, C.; Kubota, S.; Kugel, H. W.; Lawson, J.; LeBlanc, B. P.; Lee, K. C.; Levinton, F.; Maingi, R.; Manickam, J.; Maqueda, R.; Marsala, R.; Mastrovito, D.; Mau, T. K.; Medley, S. S.; Menard, J.; Meyer, H.; Mikkelsen, D. R.; Mueller, D.; Munsat, T.; Nelson, B. A.; Neumeyer, C.; Nishino, N.; Ono, M.; Park, H.; Park, W.; Paul, S.; Peebles, T.; Peng, M.; Phillips, C.; Pigarov, A.; Pinsker, R.; Ram, A.; Ramakrishnan, S.; Raman, R.; Rasmussen, D.; Redi, M.; Rensink, M.; Rewoldt, G.; Robinson, J.; Roney, P.; Roquemore, A. L.; Ruskov, E.; Ryan, P.; Sabbagh, S. A.; Schneider, H.; Skinner, C. H.; Smith, D. R.; Sontag, A.; Soukhanovskii, V.; Stevenson, T.; Stotler, D.; Stratton, B.; Stutman, D.; Swain, D.; Synakowski, E.; Takase, Y.; Taylor, G.; Tritz, K.; von Halle, A.; Wade, M.; White, R.; Wilgen, J.; Williams, M.; Wilson, J. R.; Zhu, W.; Zweben, S. J.; Akers, R.; Beiersdorfer, P.; Betti, R.; Bigelow, T.; Bitter, M.; Bonoli, P.; Bourdelle, C.; Chang, C. S.; Chrzanowski, J.; Domier, C.; Dudek, L.; Efthimion, P. C.; Finkenthal, M.; Fredd, E.; Fu, G. Y.; Glasser, A.; Goldston, R. J.; Greenough, N. L.; Grisham, L. R.; Gorelenkov, N.; Guazzotto, L.; Hawryluk, R. J.; Hogan, J.; Houlberg, W.; Humphreys, D.; Jaeger, F.; Kalish, M.; Krasheninnikov, S.; Lao, L. L.; Lawrence, J.; Leuer, J.; Liu, D.; Luhmann, N. C.; Mazzucato, E.; Oliaro, G.; Pacella, D.; Parsells, R.; Schaffer, M.; Semenov, I.; Shaing, K. C.; Shapiro, M. A.; Shinohara, K.; Sichta, P.; Tang, X.; Vero, R.; Walker, D.; Wampler, W.

    2005-10-01

    The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high ?T in order to advance the spherical torus (ST) concept. In order to do this, NSTX utilizes up to 7.5 MW of neutral beam injection, up to 6 MW of high harmonic fast waves (HHFWs), and it operates with plasma currents up to 1.5 MA and elongations of up to 2.6 at a toroidal field up to 0.45 T. New facility, and diagnostic and modelling capabilities developed over the past two years have enabled the NSTX research team to make significant progress towards establishing this physics basis for future ST devices. Improvements in plasma control have led to more routine operation at high elongation and high ?T (up to ~40%) lasting for many energy confinement times. ?T can be limited by either internal or external modes. The installation of an active error field (EF) correction coil pair has expanded the operating regime at low density and has allowed for initial resonant EF amplification experiments. The determination of the confinement and transport properties of NSTX plasmas has benefitted greatly from the implementation of higher spatial resolution kinetic diagnostics. The parametric variation of confinement is similar to that at conventional aspect ratio but with values enhanced relative to those determined from conventional aspect ratio scalings and with a BT dependence. The transport is highly dependent on details of both the flow and magnetic shear. Core turbulence was measured for the first time in an ST through correlation reflectometry. Non-inductive start-up has been explored using PF-only and transient co-axial helicity injection techniques, resulting in up to 140 kA of toroidal current generated by the latter technique. Calculated bootstrap and beam-driven currents have sustained up to 60% of the flat-top plasma current in NBI discharges. Studies of HHFW absorption have indicated parametric decay of the wave and associated edge thermal ion heating. Energetic particle modes, most notably toroidal Alfvén eigenmodes and fishbone-like modes result in fast particle losses, and these instabilities may affect fast ion confinement on devices such as ITER. Finally, a variety of techniques has been developed for fuelling and power and particle control.

  15. The magnetic anomaly model of the Jovian magnetosphere - Predictions for Voyager

    Microsoft Academic Search

    A. J. Dessler; U. M. Vasyliunas

    1979-01-01

    The magnetic anomaly model, in which the anomalously weak magnetic field region in the northern hemisphere of Jupiter influences the outer Jovian magnetosphere by one or more plasma interaction processes, has been put forth to account for the various observed Jovian magnetospheric phenomena that show evidence of Jovian longitudinal asymmetry or planetary spin periodicity. From this model, normalized by empirical

  16. Microwave radiation measurements near the electron plasma frequency of the NASA Lewis bumpy torus plasma

    NASA Technical Reports Server (NTRS)

    Mallavarpu, R.; Roth, J. R.

    1978-01-01

    Microwave emission near the electron plasma frequency was observed, and its relation to the average electron density and the dc toroidal magnetic field was examined. The emission was detected using a spectrum analyzer and a 50 omega miniature coaxial probe. The radiation appeared as a broad amplitude peak that shifted in frequency as the plasma parameters were varied. The observed radiation scanned an average plasma density ranging from 10 million/cu cm to 8 hundred million/cu cm. A linear relation was observed betweeen the density calculated from the emission frequency and the average plasma density measured with a microwave interferometer. With the aid of a relative density profile measurement of the plasma, it was determined that the emissions occurred from the outer periphery of the plasma.

  17. Local Regulation of Interchange Turbulence in a Dipole-Confined Plasma Torus using Current-Collection Feedback

    NASA Astrophysics Data System (ADS)

    Roberts, T. Maximillian

    2014-10-01

    Turbulence in a dipole-confined plasma is dominated by interchange fluctuations with complex dynamics and short coherence. We report the first laboratory demonstration of the regulation of interchange turbulence in a plasma torus confined by an axisymmetric dipole magnet using active feedback. Feedback is performed by varying the bias to an electrode in proportion to the electric potential measured at other locations. The phase and amplitude of the bias to the electrode is adjusted with a linear circuit, forming a relatively broad-band current-collection feedback system. Changing the gain and phase of collection results in modification of turbulent fluctuations, observed as amplification or suppression of turbulent spectrum. Significantly, power can be either extracted from or injected into the turbulence. When the gain and phase are adjusted to suppress turbulence, the external circuit becomes a controlled load extracting power from the plasma. This is analogous to the regulation of magnetospheric convection by ionospheric currents. When the gain and phase of the external circuit is adjusted to amplify turbulence, the direction of power flow from the electrode reverses, enhancing the fluctuations. Although we observe significant changes to the intensity and spectrum of plasma fluctuations, these changes appear only on those magnetic field lines within a region near the current collector equal in size to the turbulent correlation length and shifted in the direction of the electron magnetic drift. We conclude that the effects of this feedback on turbulence in a dipole plasma torus is localized. The clear influence of current-collection feedback on interchange turbulence suggests the possibility of global regulation of turbulent motion using multiple sensor and electrode pairs as well as the ability to perform controlled tests of bounce-averaged gyrokinetic theory of turbulence in the geometry of a dipole plasma torus. Supported by NSF-DOE Partnership for Plasma Science and DOE Grant DE-FG02-00ER54585 and NSF Award PHY-1201896.

  18. Progress towards high performance plasmas in the National Spherical Torus Experiment (NSTX)

    Microsoft Academic Search

    S. M. Kaye; M. G. Bell; R. E. Bell; S. Bernabei; J. Bialek; T. Biewer; W. Blanchard; J. Boedo; C. Bush; M. D. Carter; W. Choe; N. Crocker; D. S. Darrow; W. Davis; L. Delgado-Aparicio; S. Diem; J. Ferron; A. Field; J. Foley; E. D. Fredrickson; D. A. Gates; T. Gibney; R. Harvey; R. E. Hatcher; W. Heidbrink; K. Hill; J. C. Hosea; T. R. Jarboe; D. W. Johnson; R. Kaita; C. Kessel; S. Kubota; H. W. Kugel; J. Lawson; B. P. LeBlanc; K. C. Lee; F. Levinton; R. Maingi; J. Manickam; R. Maqueda; R. Marsala; D. Mastrovito; T. K. Mau; S. S. Medley; J. Menard; H. Meyer; D. R. Mikkelsen; D. Mueller; T. Munsat; B. A. Nelson; C. Neumeyer; N. Nishino; M. Ono; S. Paul; T. Peebles; M. Peng; C. Phillips; A. Pigarov; R. Pinsker; A. Ram; S. Ramakrishnan; R. Raman; D. Rasmussen; M. Redi; M. Rensink; G. Rewoldt; J. Robinson; P. Roney; A. L. Roquemore; E. Ruskov; P. Ryan; S. A. Sabbagh; H. Schneider; C. H. Skinner; D. R. Smith; A. Sontag; V. Soukhanovskii; T. Stevenson; D. Stotler; B. Stratton; D. Stutman; D. Swain; E. Synakowski; Y. Takase; G. Taylor; K. Tritz; A. von Halle; M. Wade; R. White; J. Wilgen; M. Williams; J. R. Wilson; W. Zhu; S. J. Zweben; R. Akers; P. Beiersdorfer; R. Betti; T. Bigelow; M. Bitter; P. Bonoli; C. Bourdelle; C. S. Chang; J. Chrzanowski; C. Domier; L. Dudek; P. C. Efthimion; M. Finkenthal; E. Fredd; G. Y. Fu; A. Glasser; R. J. Goldston; N. L. Greenough; L. R. Grisham; N. Gorelenkov; L. Guazzotto; R. J. Hawryluk; J. Hogan; W. Houlberg; D. Humphreys; F. Jaeger; M. Kalish; S. Krasheninnikov; L. L. Lao; J. Lawrence; J. Leuer; D. Liu; N. C. Luhmann; E. Mazzucato; G. Oliaro; D. Pacella; R. Parsells; M. Schaffer; I. Semenov; K. C. Shaing; M. A. Shapiro; K. Shinohara; P. Sichta; X. Tang; R. Vero; D. Walker; W. Wampler

    2005-01-01

    The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high betaT in order to advance the spherical torus (ST) concept. In order to do this, NSTX utilizes up to 7.5 MW of neutral beam injection, up to 6 MW of high harmonic fast waves (HHFWs), and it

  19. Impact of the Ulysses velocity on the diagnosis of the electron density by the Unified Radio and Plasma Wave sounder in the outskirts of the Io torus

    Microsoft Academic Search

    Philippe Le Sager; Patrick Canu; Nicole Cornilleau-Wehrlin

    1998-01-01

    The resonance spectra collected on February 8, 1992, in the outskirts of the Io plasma torus by the Unified Radio and Plasma wave (URAP) relaxation sounder on board the Ulysses spacecraft present significant differences from the active spectra gathered by earthbound spacecraft in similar plasma conditions. The most striking anomaly is the lack of resonances at the harmonics of the

  20. Mass and Energy Flow Through the Jovian Magnetosphere

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; Delamere, P. A.

    2010-12-01

    We a simple model of the flow of mass and energy through the jovian magnetosphere based on Voyager, Galileo and Cassini data. Combining the observed distribution of mass with conservation of the ~500 kg/s flux of Iogenic material we derive net radial flows that reach the local Alfven speed around 50-60 Rj. Estimates of mass ejected down the magnetotail in plasmoids only add up to a few percent of the source, suggesting most of the material must either be lost as a steady drizzle down the tail or leak out of the magnetopause. Approximately 230 tons of solar wind protons bombard the magnetopause each second. Thus, only a few percent leaking into the magnetosphere would swamp the mass source at Io. The dominance of sulfur and oxygen ions in the inner and middle magnetosphere indicate that little of such a solar wind source penetrates far into the magnetosphere. But mixing of iogenic and solar wind plasma (such as via Kelvin-Helmholtz instabilities) may be prevalent in the outer regions. The flow of energy through the system is not so clear to understand. Models of the physical chemistry of the Io plasma torus are consistent with a substantial source of energy from ion pick-up. But additional energy must also be pumped into the population of hot electrons (perhaps via plasma waves or as a dissipative by-product of fluxtube interchange motions). Most of the power going into the torus is radiated as UV line emission (1.2-2.5 TW) with only a little being carried by the outwardly diffusing plasma. As the plasma expands out into the large volumes of the middle and outer magnetosphere one would expect the plasma to cool. But the plasma temperature is observed to increase with distance and one of the major unresolved mysteries of the magnetosphere is how the plasma is in fact heated as it moves outwards. Approximately 0.6-3 TW of kinetic energy and 2.7-15 TW of thermal energy must be added to the plasma in the plasma disk. The ultimate source of this energy is likely Jupiter's rotation (coupled to the magnetodisk via the magnetic field) but some of the 2 x 10^4 TW of kinetic energy of the solar wind impinging on the magnetotail is likely tapped in the outer magnetosphere.

  1. High confinement plasmas in the Madison Symmetric Torus reversed-field pincha...

    E-print Network

    Biewer, Theodore

    . F. Almagri, J. K. Anderson, T. M. Biewer, P. K. Chattopadhyay, C.-S. Chiang, D. Craig, D. J. Den confinement in the Madison Symmetric Torus Dexter et al., Fusion Technol. 19, 131 1991 reversed-field pinch

  2. Study of High Performance Spherical Torus Formation Using Plasma Merging in the TS-4 Device

    NASA Astrophysics Data System (ADS)

    Kawamori, Eiichirou; Igarashi, Takurou; Ono, Yasushi; Katsurai, Makoto

    2003-10-01

    Formation of a high beta spherical tokamak (ST) using plasma merging has been intensively explored in the TS-3 merging experiment [1]. It is of great interest to demonstrate the high performance ST formation by use of merging in the up-scaled TS-4 device. First result of the new formation method of a high beta ST using the Reversed-Field Pinch (RFP)-ST merging [2] was obtained. In the RFP-ST merging method, the ST is produced by the counterhelicity merging under the condition that the external toroidal field is applied. We are also in the process of the ST experiment by use of the FRC-Bt method in TS-4. In the FRC-Bt method, an oblate field-reversed configuration (FRC) is initially formed by two merging spheromaks with opposing toroidal field Bt and is transformed into an ultra-high-beta ST by fast ramp-up of external Bt[1]. Preliminary result of the FRC-Bt experiment in TS-4 will be also shown. [1] Y. Ono, T. Kimura, Y. Murata, S. Miyazaki, Y. Ueda, M. Inomoto, A.L. Balandin, M. Katsurai, EX/P3-15 [2] M. Katsurai, M. Tsuruda, Y. Ono: ÒOverview of Compact Tori and Spherical Tokamak Researches with TS-3 and TS-4 Machines at University of TokyoÓ, Joint Meeting of the 3rd International Atomic Energy Agency Technical Committee Meeting on Spherical Tori and 8th International Spherical Torus Workshop, and US-Japan Workshop on Spherical Tokamak, PPPL, Princeton University, Princeton, NJ, U.S.A. (Nov. 2002).

  3. Spherical torus fusion reactor

    Microsoft Academic Search

    Peng; Yueng-Kay M

    1989-01-01

    A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment

  4. Ulysses radio and plasma wave observations in the Jupiter environment

    NASA Technical Reports Server (NTRS)

    Stone, R. G.; Pedersen, B. M.; Harvey, C. C.; Canu, P.; Cornilleau-Wehrlin, N.; Desch, M. D.; De Villedary, C.; Fainberg, J.; Farrell, W. M.; Goetz, K.

    1992-01-01

    The Unified Radio and Plasma Wave (URAP) experiment has produced new observations of the Jupiter environment, owing to the unique capabilities of the instrument and the traversal of high Jovian latitudes. Broad-band continuum radio emission from Jupiter and in situ plasma waves have proved valuable in delineating the magnetospheric boundaries. Simultaneous measurements of electric and magnetic wave fields have yielded new evidence of whistler-mode radiation within the magnetosphere. Observations of auroral-like hiss provided evidence of a Jovian cusp. The source direction and polarization capabilities of URAP have demonstrated that the outer region of the Io plasma torus supported at least five separate radio sources that reoccurred during successive rotations with a measurable corotation lag. Thermal noise measurements of the Io torus densities yielded values in the densest portion that are similar to models suggested on the basis of Voyager observations of 13 years ago. The URAP measurements also suggest complex beaming and polarization characteristics of Jovian radio components. In addition, a new class of kilometer-wavelength striated Jovian bursts has been observed.

  5. Fishbones in Joint European Torus plasmas with high ion-cyclotron-resonance-heated fast ions energy content

    SciTech Connect

    Nabais, F.; Borba, D.; Mantsinen, M.; Nave, M.F.F.; Sharapov, S.E.; Joint [Association European Atomic Energy Community/Instituto Superior Tecnico (EURATOM/IST), Centro de Fusyo Nuclear, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Association European Atomic Energy Community/National Technology Agency (EURATOM/TEKES), Helsinki University of Technology, Espoo (Finland); Association European Atomic Energy Community/Instituto Superior Tecnico (EURATOM/IST), Centro de Fusyo Nuclear, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Association European Atomic Energy Community/United Kingdom Atomic Energy Authority (EURATOM/UKAEA) Fusion Association, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom)

    2005-10-01

    In Joint European Torus (JET) [P. J. Lomas, Plasma Phys. Controled Fusion 31, 1481 (1989)], discharges with ion cyclotron resonance heating only, low-density plasmas and high fast ions energy contents provided a scenario where fishbones behavior has been observed to be related with sawtooth activity: Crashes of monster sawteeth abruptly changed the type of observed fishbones from low-frequency fishbones [B. Coppi and F. Porcelli, Phys. Rev. Lett. 57, 2272 (1986)] to high-frequency fishbones [L. Chen, R. White, and M. Rosenbluth, Phys. Rev. Lett. 52, 1122 (1984)]. During periods between crashes, the type of observed fishbones gradually changed in the opposite way. Two new fishbones regimes have been observed in intermediate stages: Fishbones bursts covering both high and low frequencies and low amplitude bursts of both types occurring simultaneously. Both sawtooth and fishbones behavior have been explained using a variational formalism.

  6. Development of a radio frequency ion source with multi-helicon plasma injectors for neutral beam injection system of Versatile Experiment Spherical Torus.

    PubMed

    Choe, Kyumin; Jung, Bongki; Chung, Kyoung-Jae; Hwang, Y S

    2014-02-01

    Despite of high plasma density, helicon plasma has not yet been applied to a large area ion source such as a driver for neutral beam injection (NBI) system due to intrinsically poor plasma uniformity in the discharge region. In this study, a radio-frequency (RF) ion source with multi-helicon plasma injectors for high plasma density with good uniformity has been designed and constructed for the NBI system of Versatile Experiment Spherical Torus at Seoul National University. The ion source consists of a rectangular plasma expansion chamber (120 × 120 × 120 mm(3)), four helicon plasma injectors with annular permanent magnets and RF power system. Main feature of the source is downstream plasma confinement in the cusp magnetic field configuration which is generated by arranging polarities of permanent magnets in the helicon plasma injectors. In this paper, detailed design of the multi-helicon plasma injector and plasma characteristics of the ion source are presented. PMID:24593595

  7. Model of Jovian F region ionosphere (Jovian ionosphere model in offset dipole approximation)

    NASA Technical Reports Server (NTRS)

    Tan, A.

    1990-01-01

    The geomagnetic control of the Earth's atmosphere is well understood. In the F-region and the topside ionosphere, non-electrical forces transport plasma along the magnetic field lines only. In consequence, the worldwide distribution of ionization is strongly dependent on the dip angle. For example, the equatorial anomaly is roughly symmetrical about the dipole equator rather than the geographic. The same appears to be the case in the Jovian ionosphere (Mahajan, 1981). The influence of the magnetic field of Jupiter on its ionization pattern is one of several outstanding topics which need to be studied. Tan (1986) investigated the formation of the equatorial anomaly in the Jovian ionosphere under a centered dipole model. Tan (1988) further studied the effect of the tilt of the Jovian dipole. The results were in broad agreement with those of a diffusive equilibrium model (Tan and Wu, 1981). An off-centered dipole model is constructed and its effects on the ionization pattern are investigated.

  8. Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma.

    PubMed

    Yatsuka, Eiichi; Kinjo, Kiyotake; Morikawa, Junji; Ogawa, Yuichi

    2009-02-01

    To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45 GHz, 2.5 kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10 W) separate frequency (1-2.1 GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35 mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1 mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic. PMID:19256646

  9. Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma

    NASA Astrophysics Data System (ADS)

    Yatsuka, Eiichi; Kinjo, Kiyotake; Morikawa, Junji; Ogawa, Yuichi

    2009-02-01

    To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45GHz, 2.5kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10W) separate frequency (1-2.1GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic.

  10. Single and multiple ionization of sulfur atoms by electron impact. [in Io plasma torus

    NASA Technical Reports Server (NTRS)

    Ziegler, D. L.; Newman, J. H.; Goeller, L. N.; Smith, K. A.; Stebbings, R. F.

    1982-01-01

    In 1979 significant concentrations of singly and multiply charged sulfur ions were observed in the Io torus. Attempts to model these observations revealed a need for new fundamental cross section data. In response, laboratory measurements of the cross-sections for single, double, triple and quadruple ionization of sulfur atoms by electron impact are presented for collision energies from threshold to 500 eV.

  11. Investigation of self-organized criticality behavior of edge plasma transport in Torus experiment of technology oriented research

    SciTech Connect

    Xu, Y.H.; Jachmich, S.; Weynants, R.R.; Huber, A.; Unterberg, B.; Samm, U. [Laboratory for Plasma Physics, Ecole Royale Militaire/Koninklijke Militaire School, Euratom-Belgian State Association, Avenue de la Renaissance 30, B-1000 Brussels (Belgium); Institute fuer plasmaphysik, Forschungzentrum Juelich GmbH, D-52425 Juelich (Germany)

    2004-12-01

    The self-organized criticality (SOC) behavior of the edge plasma transport has been studied using fluctuation data measured in the plasma edge and the scrape-off layer of Torus experiment of technology oriented research tokamak [H. Soltwisch et al., Plasma Phys. Controlled Fusion 26, 23 (1984)] before and during the edge biasing experiments. In the 'nonshear' discharge phase before biasing, the fluctuation data clearly show some of the characteristics associated with SOC, including similar frequency spectra to those obtained in 'sandpile' transport and other SOC systems, slowly decaying long tails in the autocorrelation function, values of Hurst parameters larger than 0.5 at all the detected radial locations, and a radial propagation of avalanchelike events in the edge plasma area. During the edge biasing phase, with the generation of an edge radial electric field E{sub r} and thus of E{sub r}xB flow shear, contrary to theoretical expectation, the Hurst parameters are substantially enhanced in the negative flow shear region and in the scrape-off layer as well. Concomitantly, it is found that the local turbulence is well decorrelated by the E{sub r}xB velocity shear, consistent with theoretical predictions.

  12. Large density variation predicted along the magnetic axis for cold electron plasmas in the Columbia Nonneutral Torus (CNT)

    SciTech Connect

    Lefrancois, Remi G.; Pedersen, Thomas Sunn [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

    2006-12-15

    Cold pure electron plasmas confined in Penning-Malmberg traps with mirror fields are known to exhibit density variations along field lines, such that the density is roughly proportional to the magnetic field strength, n{approx}B. The Columbia Nonneutral Torus (CNT) is the first stellarator designed to study pure electron plasmas, and exhibits substantial mirroring, with B{sub max}{approx_equal}1.8B{sub min}. However, results of a three-dimensional equilibrium solver, presented in this Letter, predict a factor of 5.3 increase in density from the minimum-field cross section to the maximum-field cross section along the magnetic axis, for a 1.5 cm Debye length plasma (a{approx_equal}15 cm for CNT). In this Letter, it is shown that the density variation of electron plasmas in mirror traps can be significantly enhanced in a device that has a cross section that varies from cylinder-like to slab-like, such as the CNT. A simple analytic expression is derived that describes the axial density variation in such a device, and it is found to agree well with the computational predictions for CNT.

  13. Triggered Jovian radio emissions

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1985-01-01

    Certain Jovian radio emissions seem to be triggered from outside, by much weaker radio waves from the sun. Recently found in the Voyager observations near Jupiter, such triggering occurs at hectometric wavelengths during the arrival of solar radio bursts, with the triggered emissions lasting sometimes more than an hour as they slowly drifted toward higher frequencies. Like the previous discovery of similar triggered emissions at the earth, this suggests that Jupiter's emissions might also originate from natural radio lasers.

  14. ?-Limiting MHD instabilities in improved-performance NSTX spherical torus plasmas

    NASA Astrophysics Data System (ADS)

    Menard, J. E.; Bell, M. G.; Bell, R. E.; Fredrickson, E. D.; Gates, D. A.; Kaye, S. M.; LeBlanc, B. P.; Maingi, R.; Mueller, D.; Sabbagh, S. A.; Stutman, D.; Bush, C. E.; Johnson, D. W.; Kaita, R.; Kugel, H. W.; Maqueda, R. J.; Paoletti, F.; Paul, S. F.; Ono, M.; Peng, Y.-K. M.; Skinner, C. H.; Synakowski, E. J.; NSTX Research Team

    2003-05-01

    Global magnetohydrodynamic (MHD) stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access to higher normalized ? and lower internal inductance. Second, the correction of a poloidal field coil induced error-field has largely eliminated locked tearing modes during normal operation and increased the maximum achievable ?. As a result of these improvements, peak ? values have reached (not simultaneously) ?T = 35%, ?N = 6.4, langle?Nrangle = 4.5, ?N/li = 10, and ?P = 1.4. High ?P operation with reduced tearing activity has allowed a doubling of discharge pulse-length to just over 1 s with sustained periods of ?Napprox6 above the ideal no-wall limit and near the with-wall limit. Details of the ?-limit scalings and ?-limiting instabilities in various operating regimes are described.

  15. Spherical torus fusion reactor

    DOEpatents

    Peng, Yueng-Kay M. (Oak Ridge, TN)

    1989-01-01

    A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment vessel wall, the fusion reactor features an exceptionally small aspect ratio (typically about 1.5), a naturally elongated plasma cross section without extensive field shaping, requires low strength magnetic containment fields, small size and high beta. These features combine to produce a spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost.

  16. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    SciTech Connect

    Kaita, R; Jajeski, R; Boaz, M; Efthimion, P; Gettelfinger, G; Gray, T; Hoffman, D; Jardin, S; Kugel, H; Marfuta, P; Munsat, T; Neumeyer, C; Raftopoulos, S; Soukhanovskii, V; Spaleta, J; Taylor, G; Timberlake, J; Woolley, R; Zakharov, L; Finkenthal, M; Stutman, D; Delgado-Aparicio, L; Seraydarian, R; Antar, G; Doerner, R; Luckhardt, S; Baldwin, M; Conn, R; Maingi, R; Menon, M; Causey, R; Buchenauer, D; Ulrickson, M; Jones, B; Rodgers, D

    2004-06-03

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  17. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    SciTech Connect

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; G. Gettelfinger; T. Gray; D. Hoffman; S. Jardin; H. Kugel; P. Marfuta; T. Munsat; C. Neumeyer; S. Raftopoulos; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; L. Delgado-Aparicio; R.P. Seraydarian; G. Antar; R. Doerner; S. Luckhardt; M. Baldwin; R.W. Conn; R. Maingi; M. Menon; R. Causey; D. Buchenauer; M. Ulrickson; B. Jones; D. Rodgers

    2004-06-07

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  18. Progress in understanding error-field physics in NSTX spherical torus plasmas

    SciTech Connect

    Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Bell, R. E. [Princeton Plasma Physics Laboratory (PPPL); Gates, D.A. [Princeton Plasma Physics Laboratory (PPPL); Gerhardt, S.P. [Princeton Plasma Physics Laboratory (PPPL); Park, J.-K. [Princeton Plasma Physics Laboratory (PPPL); Sabbagh, S. A. [Columbia University; Berkery, J.W. [Columbia University; Egan, A. [University of Pennsylvania; Kallman, J. [Princeton Plasma Physics Laboratory (PPPL); Kaye, S. M. [Princeton Plasma Physics Laboratory (PPPL); LeBlanc, B [Princeton Plasma Physics Laboratory (PPPL); Liu, Y. Q. [Culham Science Center, Abington, UK; Sontag, Aaron C [ORNL; Swanson, D. [Princeton Plasma Physics Laboratory (PPPL); Yuh, H. [Nova Photonics; Zhu, W. [Credit Suisse, New York, NY

    2010-01-01

    The low-aspect ratio, low magnetic field and wide range of plasma beta of NSTX plasmas provide new insight into the origins and effects of magnetic field errors. An extensive array of magnetic sensors has been used to analyse error fields, to measure error-field amplification and to detect resistive wall modes (RWMs) in real time. The measured normalized error-field threshold for the onset of locked modes shows a linear scaling with plasma density, a weak to inverse dependence on toroidal field and a positive scaling with magnetic shear. These results extrapolate to a favourable error-field threshold for ITER. For these low-beta locked-mode plasmas, perturbed equilibrium calculations find that the plasma response must be included to explain the empirically determined optimal correction of NSTX error fields. In high-beta NSTX plasmas exceeding the n = 1 no-wall stability limit where the RWM is stabilized by plasma rotation, active suppression of n = 1 amplified error fields and the correction of recently discovered intrinsic n = 3 error fields have led to sustained high rotation and record durations free of low-frequency core MHD activity. For sustained rotational stabilization of the n = 1 RWM, both the rotation threshold and the magnitude of the amplification are important. At fixed normalized dissipation, kinetic damping models predict rotation thresholds for RWM stabilization to scale nearly linearly with particle orbit frequency. Studies for NSTX find that orbit frequencies computed in general geometry can deviate significantly from those computed in the high-aspect ratio and circular plasma cross-section limit, and these differences can strongly influence the predicted RWM stability. The measured and predicted RWM stability is found to be very sensitive to the E x B rotation profile near the plasma edge, and the measured critical rotation for the RWM is approximately a factor of two higher than predicted by the MARS-F code using the semi-kinetic damping model.

  19. The Jovian HOM and bKOM radio emissions observed by Wind\\/\\/WAVES and by Ulysses\\/\\/URAP

    Microsoft Academic Search

    C. H. Barrow; A. Lecacheux; R. J. MacDowall; M. L. Kaiser

    2001-01-01

    During 1995 and into 1996, both the Jovian hectometric radio emission (HOM) and the Jovian broadband radio emission (bKOM) were received occasionally by the Radio and Plasma Wave Investigation (WAVES) on board the Wind spacecraft and by the Unified Radio and Plasma Experiment (URAP) on board the Ulysses spacecraft. Ulysses was then at distances of 5 AU or more from

  20. The Jovian HOM and bKOM radio emissions observed by Wind\\/WAVES and by Ulysses\\/URAP

    Microsoft Academic Search

    C. H. Barrow; A. Lecacheux; R. J. MacDowall; M. L. Kaiser

    2001-01-01

    During 1995 and into 1996, both the Jovian hectometric radio emission (HOM) and the Jovian broadband radio emission (bKOM) were received occasionally by the Radio and Plasma Wave Investigation (WAVES) on board the Wind spacecraft and by the Unified Radio and Plasma Experiment (URAP) on board the Ulysses spacecraft. Ulysses was then at distances of 5 AU or more from

  1. Experimental observations and model calculations of impurity radiation in a plasma gun compact torus experiment

    SciTech Connect

    Goldenbaum, G.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Turner, W.C.

    1982-08-10

    Several types of radiation measurements were performed on the Beta II compact forms experiment. Among these are time integrated spectra ranging in wavelength from the vuv to the uv, time resolved bolometer measurements of radiation from the x-ray to the infrared, and time and wavelength resolved measurements of certain spectral lines. It is difficult to relate any one of these measurements to plasma parameters of interest such as temperature, density, or impurity content. In this report we compare the results of these, and other measurements with two simple models of the power balance in the plasma in order to estimate the effect of carbon and oxygen impurities on plasma lifetime.

  2. Beta-limiting MHD Instabilities in Improved-performance NSTX Spherical Torus Plasmas

    SciTech Connect

    J.E. Menard; M.G. Bell; R.E. Bell; E.D. Fredrickson D.A. Gates: S.M. Kaye; B.P. LeBlanc; R. Maingi; D. Mueller; S.A. Sabbagh; D. Stutman; C.E. Bush; D.W. Johnson; R. Kaita; H.W. Kugel; R.J. Maqueda; F. Paoletti; S.F Paul; M. Ono; Y.-K.M. Peng; C.H. Skinner; E.J. Synakowski; the NSTX Research Team

    2003-05-29

    Global magnetohydrodynamic stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access to higher normalized beta and lower internal inductance. Second, the correction of a poloidal field coil induced error-field has largely eliminated locked tearing modes during normal operation and increased the maximum achievable beta. As a result of these improvements, peak beta values have reached (not simultaneously) {beta}{sub t} = 35%, {beta}{sub N} = 6.4, <{beta}{sub N}> = 4.5, {beta}{sub N}/l{sub i} = 10, and {beta}{sub P} = 1.4. High {beta}{sub P} operation with reduced tearing activity has allowed a doubling of discharge pulse-length to just over 1 second with sustained periods of {beta}{sub N} {approx} 6 above the ideal no-wall limit and near the with-wall limit. Details of the {beta} limit scalings and {beta}-limiting instabilities in various operating regimes are described.

  3. Momentum-Transport Studies in High E B Shear Plasmas in the National Spherical Torus Experiment

    E-print Network

    Princeton Plasma Physics Laboratory

    . Yuh Nova Photonics Inc., Princeton, New Jersey 08540, USA S. A. Sabbagh Department of Applied Physics acknowledged as playing a central role in the performance of fusion plasmas. It has been shown to be beneficial

  4. Investigations of the magnetic structure and the decay of a plasma-gun-generated compact torus

    NASA Astrophysics Data System (ADS)

    Turner, W. C.; Goldenbaum, G. C.; Granneman, E. H. A.; Hammer, J. H.; Hartman, C. W.; Prono, D. S.; Taska, J.

    1983-07-01

    The results of a series of experimental measurements of compact toroidal (CT) plasmas produced by a magnetized coaxial plasma gun injecting into a flux-conserving metallic liner are reported. The experiments were performed on the Beta II facility at Lawrence Livermore National Laboratory. The magnetic equilibria are well described by a force-free eigenmode structure that results from an extension of Taylor's theory of the reversed-field pinch. Consideration of helicity conservation during relaxation of the composite plasma-gun flux-conserver system to the final state equilibrium yields theoretical expressions that are compared with the experiment. In particular the CT poloidal flux (?pol) and the overall electrical efficiency for producing the CT are predicted to be functions of the plasma gun inner-electrode flux (?gun) and the volt-seconds input to the gun discharge (??0 V dt). Away from a cutoff at too low values of ??0 V dt or too high values, ?gun ,?pol scales linearly with the square root of the product of ?gun and ??0 V dt, whereas the electrical efficiency equals about 13% for ??0 V dt/?gun ?10. For an electrical energy input Win =45 kJ, CT's are produced with poloidal plus toroidal field energy up to WB =8 kJ and toroidal plasma current Itor =330 kA. The chord-averaged plasma density is 2-4×1014 cm-3, and the plasma volume equals 150 liters. The radius of the flux conserver is 37.5 cm, and the axial length is 40 cm. If a bias flux ?b is superimposed on the flux conserver, n=1 tilting is observed when ?b/?pol exceeds a ratio of about 0.20 to 0.25. Impurity radiation measured by a pyroelectric detector accounts for all of the plasma magnetic energy if uniform volume emission of radiation is assumed. The dominant impurities observed are carbon and oxygen. Helium-like lines are not observed, indicating that the plasma has not ``burned through'' the low electron temperature radiation maxima. The experimentally observed decay times (defined by the e-folding time of plasma magnetic fields) are 80 to 160 ?sec—consistent with Zeff =2 and Te in the range 5-10 eV if classical resistivity is assumed. A zero-dimensional rate equation model of impurity radiation loss gives a reasonably good account of the experimental observations and predicts that the carbon concentration must be reduced to the level of a few percent to allow burnthrough of the low-Te carbon radiation barrier. Glow discharge cleaning of the gun electrodes and flux conserver resulted in a 20% increase of the e-folding time of plasma magnetic fields (from an average value 115 to 140 ?sec). The CT plasma density was observed to scale linearly with the electrical energy input to the gun discharge and to be only weakly dependent on the filling pressure and timing of pulsed deuterium gas valves. It seems likely that further improvements in increasing plasma lifetime can be made by improving the vacuum conditions and discharge cleaning methods and experimenting with the gun electrode materials.

  5. Analytic axisymmetric magnetohydrodynamic equilibria of a plasma torus with toroidal mass flow

    SciTech Connect

    Throumoulopoulos, G. N.; Pantis, G.

    1989-09-01

    Several classes of analytic equilibria of a toroidal axisymmetric plasma with toroidal mass flow are obtained for isothermal as well as isentropic magnetic surfaces under various pressure and toroidal current density profiles. The effects of flow on certain global equilibrium and stability characteristics are examined. It is shown that for a wide family of equilibria the average beta /l angle/ /beta//r angle/ does not depend explicitly on flow and falls within the limits of static equilibria. In particular, for the case of field-reversed configurations /l angle/ /beta//r angle/ is totally independent of plasma flow. Calculations based on a specific equilibrium solution for a tokamak with fixed average toroidal magnetic energy show that plasma elongation is an increasing function of the Mach number whereas the safety factor is a decreasing function of it.

  6. Positional Coincidence of H2O Maser and a Plasma Obscuring Torus in Radio Galaxy NGC 1052

    E-print Network

    Satoko Sawada-Satoh; Seiji Kameno; Kayoko Nakamura; Daichi Namikawa; Katsunori M. Shibata; Makoto Inoue

    2008-02-28

    We present multi-frequency simultaneous VLBA observations at 15, 22 and 43 GHz towards the nucleus of the nearby radio galaxy NGC 1052. These three continuum images reveal a double-sided jet structure, whose relative intensity ratios imply that the jet axis is oriented close to the sky plane. The steeply rising spectra at 15-43 GHz at the inner edges of the jets strongly suggest that synchrotron emission is absorbed by foreground thermal plasma. We detected H2O maser emission in the velocity range of 1550-1850 km/s, which is redshifted by 50-350 km/s with respect to the systemic velocity of NGC 1052. The redshifted maser gas appears projected against both sides of the jet, in the same manner as the HI seen in absorption. The H2O maser gas are located where the free-free absorption opacity is large. This probably imply that the masers in NGC 1052 are associated with a circumnuclear torus or disk as in the nucleus of NGC 4258. Such circumnuclear structure can be the sence of accreting onto the central engine.

  7. Influence of plasma diagnostics and constraints on the quality of equilibrium reconstructions on Joint European Torus

    SciTech Connect

    Gelfusa, M.; Gaudio, P.; Peluso, E. [Associazione EURATOM-ENEA, University of Rome “Tor Vergata”, Roma (Italy)] [Associazione EURATOM-ENEA, University of Rome “Tor Vergata”, Roma (Italy); Murari, A.; Baruzzo, M. [Consorzio RFX-Associazione EURATOM ENEA per la Fusione, I-35127 Padova (Italy)] [Consorzio RFX-Associazione EURATOM ENEA per la Fusione, I-35127 Padova (Italy); Lupelli, I.; Hawkes, N.; Brix, M.; Drozdov, V.; Meigs, A.; Romanelli, M. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)] [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Craciunescu, T. [EURATOM-MEdC Association, NILPRP, Bucharest (Romania)] [EURATOM-MEdC Association, NILPRP, Bucharest (Romania); Schmuck, S.; Sieglin, B. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, EURATOM Association, Wendelsteinstr.1, 17491 Greifswald (Germany)] [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, EURATOM Association, Wendelsteinstr.1, 17491 Greifswald (Germany); Collaboration: JET-EFDA Contributors

    2013-10-15

    One of the main approaches to thermonuclear fusion relies on confining high temperature plasmas with properly shaped magnetic fields. The determination of the magnetic topology is, therefore, essential for controlling the experiments and for achieving the required performance. In Tokamaks, the reconstruction of the fields is typically formulated as a free boundary equilibrium problem, described by the Grad-Shafranov equation in toroidal geometry and axisymmetric configurations. Unfortunately, this results in mathematically very ill posed problems and, therefore, the quality of the equilibrium reconstructions depends sensitively on the measurements used as inputs and on the imposed constraints. In this paper, it is shown how the different diagnostics (Magnetics Measurements, Polarimetry and Motional Stark Effect), together with the edge current density and plasma pressure constraints, can have a significant impact on the quality of the equilibrium on JET. Results show that both the Polarimetry and Motional Stark Effect internal diagnostics are crucial in order to obtain reasonable safety factor profiles. The impact of the edge current density constraint is significant when the plasma is in the H-mode of confinement. In this plasma scenario the strike point positions and the plasma last closed flux surface can change even by centimetres, depending on the edge constraints, with a significant impact on the remapping of the equilibrium-dependent diagnostics and of pedestal physics studies. On the other hand and quite counter intuitively, the pressure constraint can severely affect the quality of the magnetic reconstructions in the core. These trends have been verified with several JET discharges and consistent results have been found. An interpretation of these results, as interplay between degrees of freedom and available measurements, is provided. The systematic analysis described in the paper emphasizes the importance of having sufficient diagnostic inputs and of properly validating the results of the codes with independent measurements.

  8. Influence of plasma diagnostics and constraints on the quality of equilibrium reconstructions on Joint European Torus.

    PubMed

    Gelfusa, M; Murari, A; Lupelli, I; Hawkes, N; Gaudio, P; Baruzzo, M; Brix, M; Craciunescu, T; Drozdov, V; Meigs, A; Peluso, E; Romanelli, M; Schmuck, S; Sieglin, B

    2013-10-01

    One of the main approaches to thermonuclear fusion relies on confining high temperature plasmas with properly shaped magnetic fields. The determination of the magnetic topology is, therefore, essential for controlling the experiments and for achieving the required performance. In Tokamaks, the reconstruction of the fields is typically formulated as a free boundary equilibrium problem, described by the Grad-Shafranov equation in toroidal geometry and axisymmetric configurations. Unfortunately, this results in mathematically very ill posed problems and, therefore, the quality of the equilibrium reconstructions depends sensitively on the measurements used as inputs and on the imposed constraints. In this paper, it is shown how the different diagnostics (Magnetics Measurements, Polarimetry and Motional Stark Effect), together with the edge current density and plasma pressure constraints, can have a significant impact on the quality of the equilibrium on JET. Results show that both the Polarimetry and Motional Stark Effect internal diagnostics are crucial in order to obtain reasonable safety factor profiles. The impact of the edge current density constraint is significant when the plasma is in the H-mode of confinement. In this plasma scenario the strike point positions and the plasma last closed flux surface can change even by centimetres, depending on the edge constraints, with a significant impact on the remapping of the equilibrium-dependent diagnostics and of pedestal physics studies. On the other hand and quite counter intuitively, the pressure constraint can severely affect the quality of the magnetic reconstructions in the core. These trends have been verified with several JET discharges and consistent results have been found. An interpretation of these results, as interplay between degrees of freedom and available measurements, is provided. The systematic analysis described in the paper emphasizes the importance of having sufficient diagnostic inputs and of properly validating the results of the codes with independent measurements. PMID:24188275

  9. Influence of plasma diagnostics and constraints on the quality of equilibrium reconstructions on Joint European Torus

    NASA Astrophysics Data System (ADS)

    Gelfusa, M.; Murari, A.; Lupelli, I.; Hawkes, N.; Gaudio, P.; Baruzzo, M.; Brix, M.; Craciunescu, T.; Drozdov, V.; Meigs, A.; Peluso, E.; Romanelli, M.; Schmuck, S.; Sieglin, B.; JET-EFDA Contributors

    2013-10-01

    One of the main approaches to thermonuclear fusion relies on confining high temperature plasmas with properly shaped magnetic fields. The determination of the magnetic topology is, therefore, essential for controlling the experiments and for achieving the required performance. In Tokamaks, the reconstruction of the fields is typically formulated as a free boundary equilibrium problem, described by the Grad-Shafranov equation in toroidal geometry and axisymmetric configurations. Unfortunately, this results in mathematically very ill posed problems and, therefore, the quality of the equilibrium reconstructions depends sensitively on the measurements used as inputs and on the imposed constraints. In this paper, it is shown how the different diagnostics (Magnetics Measurements, Polarimetry and Motional Stark Effect), together with the edge current density and plasma pressure constraints, can have a significant impact on the quality of the equilibrium on JET. Results show that both the Polarimetry and Motional Stark Effect internal diagnostics are crucial in order to obtain reasonable safety factor profiles. The impact of the edge current density constraint is significant when the plasma is in the H-mode of confinement. In this plasma scenario the strike point positions and the plasma last closed flux surface can change even by centimetres, depending on the edge constraints, with a significant impact on the remapping of the equilibrium-dependent diagnostics and of pedestal physics studies. On the other hand and quite counter intuitively, the pressure constraint can severely affect the quality of the magnetic reconstructions in the core. These trends have been verified with several JET discharges and consistent results have been found. An interpretation of these results, as interplay between degrees of freedom and available measurements, is provided. The systematic analysis described in the paper emphasizes the importance of having sufficient diagnostic inputs and of properly validating the results of the codes with independent measurements.

  10. Night Side Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian aurora on the night side of the planet. The upper bright arc is auroral emission seen 'edge on' above the planetary limb with the darkness of space as a background. The lower bright arc is seen against the dark clouds of Jupiter. The aurora is easier to see on the night side of Jupiter because it is fainter than the clouds when they are illuminated by sunlight. Jupiter's north pole is out of view to the upper right. The images were taken in the clear filter (visible light) and are displayed in shades of blue.

    As on Earth, the auroral emission is caused by electrically charged particles striking the upper atmosphere from above. The particles travel along the magnetic field lines of the planet, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image to the right. In multispectral observations the aurora appears red, consistent with glow from atomic hydrogen in Jupiter's atmosphere. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in sequences of Galileo images.

    North is at the top of the picture. A grid of planetocentric latitude and west longitude is overlain on the images. The images were taken on November 5, 1997 at a range of 1.3 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  11. GEOLogic: Terrestrial and Jovian Planets

    NSDL National Science Digital Library

    Laura Guertin

    In this two-part example, students are given clues about properties about the terrestrial and Jovian planets respectively and asked to match up the planet with the correct equatorial radius, mean orbital velocity, and period of rotation.

  12. Micrometeorite erosion of the man rings as a source of plasma in the inner Saturnian plasma torus

    NASA Technical Reports Server (NTRS)

    Pospieszalska, M. K.; Johnson, R. E.

    1991-01-01

    Micrometeorite bombardment is presently suggested to be a source of water molecules and molecular ions in the region between the outer edge of the main rings of Saturn and Encedalus, adding to those neutrals and plasma that are generated by the sputtering of icy satellites. In view of uncertainties concerning the magnitude and distribution of the ring source, an examination is conducted of limiting cases. The implications of such cases for the Cassini division are calculated, and a discussion of their possible relevance to the region's neutral and plasma cloud is presented.

  13. Model of Jovian F region ionosphere (Jovian ionosphere model in offset dipole approximation). Annual report No. 2

    SciTech Connect

    Tan, A.

    1990-10-01

    The geomagnetic control of the Earth's atmosphere is well understood. In the F-region and the topside ionosphere, non-electrical forces transport plasma along the magnetic field lines only. In consequence, the worldwide distribution of ionization is strongly dependent on the dip angle. For example, the equatorial anomaly is roughly symmetrical about the dipole equator rather than the geographic. The same appears to be the case in the Jovian ionosphere (Mahajan, 1981). The influence of the magnetic field of Jupiter on its ionization pattern is one of several outstanding topics which need to be studied. Tan (1986) investigated the formation of the equatorial anomaly in the Jovian ionosphere under a centered dipole model. Tan (1988) further studied the effect of the tilt of the Jovian dipole. The results were in broad agreement with those of a diffusive equilibrium model (Tan and Wu, 1981). An off-centered dipole model is constructed and its effects on the ionization pattern are investigated.

  14. Observations of electron gyroharmonic waves and the structure of the Io torus

    NASA Astrophysics Data System (ADS)

    Birmingham, T. J.; Alexander, J. K.; Desch, M. D.; Hubbard, R. F.; Pedersen, B. M.

    1980-05-01

    Narrow-banded emissions were observed by the Planetary Radio Astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near the upper hybrid resonant frequency, (fuhr) but the distribution of the other observed emissions varies in a systematic way with position in the torus. A refined model of the electron density variation, based on identification of the fuhr line, is included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot losscone electrons. The positioning of the observed auxiliary harmonics with respect to fuhr is shown to be an indicator of the cold to hot temperature ratio. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner and outer portions of the torus.

  15. Direct observation of transition to electron Bernstein waves from electromagnetic mode by three mode-conversion scenarios in the dipole confinement torus plasma

    NASA Astrophysics Data System (ADS)

    Uchijima, K.; Takemoto, T.; Morikawa, J.; Ogawa, Y.

    2015-06-01

    Direct measurement experiments on the mode conversion to the electron Bernstein wave (EBW) have been conducted in dipole confinement torus plasmas for three excitation scenarios; i.e. perpendicular injections of an eXtraordinary mode (X-mode) from the low- and high-magnetic-field sides, and the oblique injection of an Ordinary mode (O-mode) from the low-magnetic-field side. By inserting probe antennas into plasmas, wave propagation has been directly measured. At plasma conditions for the EBW excitation, several characteristics which indicate the mode conversion to the EBWs have been observed; i.e. a short wavelength wave, an electrostatic and longitudinal mode, backward propagation at the upper hybrid resonance (UHR) region. Meanwhile, the wavelengths experimentally observed might be slightly longer than those of theoretical prediction. In the case of the oblique injection of the O-mode, it has been identified that the window of the injection angle for the excitation of the EBW would be quite limited, and the optimum angle seems to be roughly in agreement with theory. These experimental results might support that the electromagnetic waves injected outside of torus plasmas reach to the UHR region and convert wave characteristics to the EBWs for three excitation scenarios.

  16. Investigation of Jovian satellites and the origin of Jovian system by LAPLACE

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho; Okada, Tatsuaki; Yamaji, Atsushi; Fujimoto, Masaki; Kasaba, Yasumasa; Kimura, Jun; Ikoma, Masahiro; Hussmann, Hauke; Kuramoto, Kiyoshi

    LAPLACE (ESA-JAXA joint mission for the Jovian system) was selected as one of future ESA scientific missions Cosmic Vision in October 2007. LAPLACE is a mission with three spacecrafts aiming at coordinated observations of Jovian satellites and the magnetosphere, atmosphere and interior of Jupiter. An orbiter around Europa or Ganymede is involved. There is a possibility that JAXA (Japan Aerospace Exploration Agency) will take a role on the magnetosphere spinner. Japanese scientists working on the origin and evolution of Jupiter, satellite evolution, and astrobiology have been participating in the LAPLACE working group in Japan. Detailed observation of Jovian satellites Europa, Ganymede, Callisto and Io as well as smaller satellites such as Amalthea would be important also for the study of the origin of Jovian system. Resurfacing processes on Europa and Ganymede should be studied to know the properties of the internal oceans. The processes can be investigated by infrared observation for salt minerals and amorphous/crystal ices. Not only the thickness of icy crust of Europa but also thickness of the ocean and its bottom topography should be important targets, which would be investigated by gravity and magnetism measurements. For both Europa and Ganymede, the surface layering and structure of icy crust should be an interesting geological target, which will be clarified by subsurface radar. In Japan, KAGUYA is observing the Moon, and Venus remote sensing mission (PLANET-C) and Mercury mission Bepi Colombo will be launched in 2011 and 2013, respectively. Several instruments such as cameras, spectrometers, a laser altimeter, a radar, a magnetometer, plasma instruments, and a dust detector should come from the heritage of instruments on board KAGUYA, PLANET-C, and BepiColombo.

  17. Generation Of High Non-inductive Plasma Current Fraction H-mode Discharges By High-harmonic Last Wave Heating In The National Spherical Torus Experiment

    SciTech Connect

    Taylor, G; Kessel, C E; LeBlanc, B P; Mueller, D; Phillips, D K; Valeo, E J; Wilson, J R; Ryan, P M; Bonoli, P T; Wright, J C

    2012-02-13

    1.4 MW of 30 MHz high-harmonic fast wave (HHFW) heating, with current drive antenna phasing, has generated a Ip = 300kA, BT (0) = 0.55T deuterium H-mode plasma in the National Spherical Torus Experiment that has a non-inductive plasma current fraction, fNI = 0.7-1. Seventy-five percent of the non-inductive current was generated inside an internal transport barrier that formed at a normalized minor radius, r/a {approx} 0.4 . Three quarters of the non-inductive current was bootstrap current and the remaining non-inductive current was generated directly by HHFW power inside r/a {approx} 0.2.

  18. Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source

    SciTech Connect

    Hossack, Aaron C.; Jarboe, Thomas R.; Victor, Brian S. [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States)] [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Firman, Taylor; Prager, James R.; Ziemba, Timothy [Eagle Harbor Technologies, Inc., 119 W. Denny Way, Suite 210, Seattle, Washington 98119 (United States)] [Eagle Harbor Technologies, Inc., 119 W. Denny Way, Suite 210, Seattle, Washington 98119 (United States); Wrobel, Jonathan S. [979B West Moorhead Circle, Boulder, Colorado 80305 (United States)] [979B West Moorhead Circle, Boulder, Colorado 80305 (United States)

    2013-10-15

    A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 10{sup 19} m{sup ?3} to 1 × 10{sup 19} m{sup ?3}. Deuterium spheromak formation is possible with density as low as 2 × 10{sup 18} m{sup ?3}. The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented.

  19. The interplanetary modulation and transport of Jovian electrons

    NASA Technical Reports Server (NTRS)

    Conlon, T. F.

    1978-01-01

    Based on simultaneous measurements by Pioneer 11 of the 3-6 MeV Jovian electron flux, interplanetary magnetic field magnitude, and solar wind speed, the interplanetary transport of energetic particles is studied. It is found that corotating interaction regions (CIR's) greatly inhibit electron transport across the average field direction. Cross-field transport is also influenced by the degree of compression of the solar wind since CIR's are areas of compressed solar wind plasma. The propagation of Jovian electrons is studied by a model that includes the effects of CIR's. The model tests whether or not the three-dimensional convection-diffusion theory adequately describes the cross-field transport of electrons. The model is also valid for Jovian electron observations from earth-orbiting satellites. The model may be further applied to 1 AU from the sun where it is found that the cross-field diffusion of electrons explains why Jovian electrons are detected at the earth even during periods when the interplanetary magnetic field does not connect the earth directly to Jupiter.

  20. Joule heating of the Jovian ionosphere by corotation enforcement currents

    NASA Astrophysics Data System (ADS)

    Nishida, A.; Watanabe, Y.

    1981-11-01

    A simple magnetodisk model is used to estimate the Joule heating rate, for several causes of departure from the corotation during whose enforcement heat is deposited on the Jovian magnetosphere. Following compression or expansion of the magnetosphere, the magnetospheric plasma sub- or super-rotates due to conservation of angular momentum and thermal energy is deposited in the ionosphere at a rate of 10 to the 12th W for 100,000 sec while rotational speed is adjusted toward the corotation with the planet. Day-night asymmetry in trajectory of rotational motion of plasma, due to magnetospheric configuration asymmetry, may also produce energy dissipation of a similar magnitude as the rotational speed is adjusted. The corotation enforcement current therefore deposits as much heat as the dynamo current from Io, and plays an important role in the energetics and dynamics of the Jovian magnetosphere.

  1. The use of neutral beam heating to produce high performance fusion plasmas, including the injection of tritium beams into the Joint European Torus (JET)

    SciTech Connect

    Thompson, E.; Stork, D.; de Esch, H.P.L. (JET Joint Undertaking, Abingdon, Oxon 0X14 3EA (United Kingdom)); the JET Team

    1993-07-01

    The neutral beam injection (NBI) system of the Joint European Torus (JET) [[ital Plasma] [ital Physics] [ital and] [ital Controlled] [ital Nuclear] [ital Fusion] [ital Research] (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 11] has proved to be an extremely effective and flexible heating method capable of producing high performance plasmas and performing a wide range of related physics experiments. High fusion performance deuterium plasmas have been obtained in the hot-ion (HI) H-mode regime, using the central particle fueling and ion heating capabilities of the NBI system in low target density plasmas, and in the pellet enhanced plasma (PEP) H-mode regime, where the good central confinement properties of pellet fueled plasmas are exploited by additional heating and fueling as well as the transition to H mode. The HI H-mode configuration was used for the First Tritium Experiment (FTE) in JET in which NBI was used to heat the plasma using 14 D[sup 0] beams and, for the first time, to inject T[sup 0] using the two remaining beams. These plasmas had a peak fusion power of 1.7 MW from deuterium--tritium (D--T) fusion reactions. The capability for injection of a variety of beam species (H[sup 0], D[sup 0], [sup 3]He[sup 0], and [sup 4]He[sup 0]) has allowed the study of confinement variation with atomic mass and the simulation of [alpha]-particle transport. Additionally, the use of the NBI system has permitted an investigation of the plasma behavior near the toroidal [beta] limit over a wide range of toroidal field strengths.

  2. Galileo dust data from the jovian system: 2000 to 2003

    NASA Astrophysics Data System (ADS)

    Krüger, H.; Bindschadler, D.; Dermott, S. F.; Graps, A. L.; Grün, E.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.; Horányi, M.; Kissel, J.; Linkert, D.; Linkert, G.; Mann, I.; McDonnell, J. A. M.; Moissl, R.; Morfill, G. E.; Polanskey, C.; Roy, M.; Schwehm, G.; Srama, R.

    2010-06-01

    The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the planet between December 1995 and September 2003. The spacecraft was equipped with a highly sensitive dust detector that monitored the jovian dust environment between approximately 2 and 370 RJ (jovian radius RJ=71 492 km). The Galileo dust detector was a twin of the one flying on board the Ulysses spacecraft. This is the tenth in a series of papers dedicated to presenting Galileo and Ulysses dust data. Here we present data from the Galileo dust instrument for the period January 2000 to September 2003 until Galileo was destroyed in a planned impact with Jupiter. The previous Galileo dust data set contains data of 2883 particles detected during Galileo's interplanetary cruise and 12 978 particles detected in the jovian system between 1996 and 1999. In this paper we report on the data of additional 5389 particles measured between 2000 and the end of the mission in 2003. The majority of the 21 250 particles for which the full set of measured impact parameters (impact time, impact direction, charge rise times, charge amplitudes, etc.) was transmitted to Earth were tiny grains (about 10 nm in radius), most of them originating from Jupiter's innermost Galilean moon Io. They were detected throughout the jovian system and the impact rates frequently exceeded 10 min -1. Surprisingly large impact rates up to 100 min -1 occurred in August/September 2000 when Galileo was far away (?280RJ) from Jupiter, implying dust ejection rates in excess of 100 kg s -1. This peak in dust emission appears to coincide with strong changes in the release of neutral gas from the Io torus. Strong variability in the Io dust flux was measured on timescales of days to weeks, indicating large variations in the dust release from Io or the Io torus or both on such short timescales. Galileo has detected a large number of bigger micron-sized particles mostly in the region between the Galilean moons. A surprisingly large number of such bigger grains was measured in March 2003 within a four-day interval when Galileo was outside Jupiter's magnetosphere at approximately 350 RJ jovicentric distance. Two passages of Jupiter's gossamer rings in 2002 and 2003 provided the first actual comparison of in-situ dust data from a planetary ring with the results inferred from inverting optical images. Strong electronics degradation of the dust instrument due to the harsh radiation environment of Jupiter led to increased calibration uncertainties of the dust data.

  3. Status of National Spherical Torus Experiment (NSTX)

    Microsoft Academic Search

    Masayuki Ono

    2001-01-01

    The main aim of National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the innovative spherical torus (ST) concept. The NSTX experimental facility has been operating reliably and its capabilities steadily improving. Due to relatively efficient ohmic current drive and benign halo current behavior, the plasma current was increased to 1.4 MA, which is well above

  4. Observations of electron gyroharmonic waves and the structure of the Io torus. [jupiter 1 spacecraft radio astronomy experiment

    NASA Technical Reports Server (NTRS)

    Birmingham, T. J.; Alexander, J. K.; Desch, M. D.; Hubbard, R. F.; Pedersen, B. M.

    1980-01-01

    Narrow-banded emissions were observed by the Planetary Radio Astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near the upper hybrid resonant frequency, (fuhr) but the distribution of the other observed emissions varies in a systematic way with position in the torus. A refined model of the electron density variation, based on identification of the fuhr line, is included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot losscone electrons. The positioning of the observed auxiliary harmonics with respect to fuhr is shown to be an indicator of the cold to hot temperature ratio. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner and outer portions of the torus.

  5. Jovian Dark Spot

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A recently discovered black spot in Jupiter's clouds is darker than any feature ever before observed on the giant planet. The spot may be the result of a downward spiraling wind that blows away high clouds and reveals deeper, very dark cloud layers. These three panels depict the same area of Jupiter's atmosphere. A map of Jovian temperatures near 250 millibar pressure (top) panel is derived from the photopolarimeter-radiometer instrument on NASA's Galileo Jupiter orbiter. This map is compared with maps derived from images of the same area in visible light (middle panel)and thermal radiation sensitive to cloud-top temperatures (bottom panel).

    The single downward-pointing arrow in the top panel indicates the location of a warm area that corresponds to the position of a so-called 'black spot'(shown in the middle panel), a feature that is about a year old. Features this dark are rare on Jupiter. The bottom panel, sensitive to temperatures at Jupiter's cloud tops, shows this feature as a bright object, meaning that upper-level cold clouds are missing - allowing us to see deeper into Jupiter's warmer interior. The dark visible appearance of the feature than most likely represents the color of very deep clouds. The warm temperatures and cloud-free conditions imply that this feature is a region where dry upper-atmospheric gas is being forced to converge, is warmed up and then forced to descend, clearing out clouds. It is the opposite of wet, upwelling gas in areas such as Jupiter's Great Red Spot or white ovals. On the other hand, it is unlike the dry and relatively cloudless feature into which the Galileo probe descended in 1995, because that region had the same temperatures as its surroundings and did not appear nearly as dark as this new spot.

    The temperatures sampled by the photopolarimeter radiometer are near the top of Jupiter's troposphere, where wind motions control the atmosphere. The top row of arrows shows the location of temperature waves in a warm region of the atmosphere. These types of waves have never been seen before. What is interesting about these waves is both that they are 'channeled' within the warm band at the top of the panel, and that they appear to have no counterpart in the visible cloud structure. Thermal waves have already been seen in Jupiter that are independent of the cloud structure, but those waves were much larger in size. This is the first time Jupiter's temperatures have been mapped at a spatial resolution better than 2,000 kilometers (1,243 miles), allowing these waves to be detected.

    These maps include an area on Jupiter between approximately the equator and 40 degrees south latitude, covering about 60 degrees of longitude. They were taken in late September during the spacecraft's 17th orbit.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

  6. Mechanism of Radial Redistribution of Energetic Trapped Ions Due to m=2/n=1 Internal Reconnection in Joint European Torus Shear Optimized Plasmas

    SciTech Connect

    N.N. Gorelenkov; A. Gondhalekar; A.A. Korotkov; S.E. Sharapov; D. Testa; and Contributors to the EFDA-JET Workprogramme

    2002-01-18

    Internal radial redistribution of MeV energy ICRF-driven hydrogen minority ions was inferred from neutral particle analyzer measurements during large amplitude MHD activity leading to internal reconnection in Shear Optimized plasmas in the Joint European Torus (JET). A theory is developed for energetic ion redistribution during a reconnection driven by an m=2/n=1 internal kink mode. Plasma motion during reconnection generates an electric field which can change the energy and radial position of the energetic ions. The magnitude of ion energy change depends on the value of the safety factor at the plasma core from which the energetic ions are redistributed. A relation is found for corresponding change in canonical momentum. P(subscript phi), which leads to radial displacement of the ions. The model yields distinctive new features of energetic ion redistribution under such conditions. Predicted characteristics of ion redistribution are compared with the NPA measurements, and good correlation is found. Sometimes fast ions were transported to the plasma edge due to interaction with a long-lived magnetic island which developed after the reconnection and had chirping frequency in the laboratory frame. Convection of resonant ions trapped in a radially moving phase-space island is modeled to understand the physics of such events.

  7. Corotation lag of the Jovian atmosphere, ionosphere, and magnetosphere

    NASA Technical Reports Server (NTRS)

    Huang, T. S.; Hill, T. W.

    1989-01-01

    The Jovian ionosphere-magnetosphere coupling model of Hill (1979) was modified to include the rotational slippage of the neutral atmosphere at ionospheric heights, relative to a frame of reference corotating rigidly with Jupiter. Equations were derived for the altitude distributions of ionospheric neutral and ion velocities, and a generalized expression was obtained for the corotation lag of the magnetosphere. The results of calculations provide independent support for the expectation that vertical mixing in Jupiter's atmosphere is much more vigorous at high latitudes than near the equator. They also indicate that the observed corotation lag in the magnetosphere and the Io torus is largely attributable to the slippage of the neutral atmosphere itself, rather than to the slippage of ionospheric ions relative to ionospheric neutrons, as previously suggested.

  8. Models of Jovian decametric radiation. [astronomical models of decametric waves

    NASA Technical Reports Server (NTRS)

    Smith, R. A.

    1975-01-01

    A critical review is presented of theoretical models of Jovian decametric radiation, with particular emphasis on the Io-modulated emission. The problem is divided into three broad aspects: (1) the mechanism coupling Io's orbital motion to the inner exosphere, (2) the consequent instability mechanism by which electromagnetic waves are amplified, and (3) the subsequent propagation of the waves in the source region and the Jovian plasmasphere. At present there exists no comprehensive theory that treats all of these aspects quantitatively within a single framework. Acceleration of particles by plasma sheaths near Io is proposed as an explanation for the coupling mechanism, while most of the properties of the emission may be explained in the context of cyclotron instability of a highly anisotropic distribution of streaming particles.

  9. Thin current sheets in the Jovian magnetotail

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Vasko, I. Y.; Kasahara, S.

    2014-06-01

    In this paper we investigate the fine structure of the current sheet located at the dawn side (and the central region) of the Jovian magnetotail (magnetodisk). We consider observational data collected by Galileo spacecraft (our dataset includes 226 current sheet crossings). Measurements of spectra of electric field fluctuations allow us to estimate the electron density. The plasma temperature is estimated from the vertical stress balance in the current sheet. To determine the vertical structure of the current sheet we use magnetic field measurements and the model of the neutral plane vertical motion. The current sheet vertical structure includes two spatial scales: the thin current sheet with the thickness around two Larmor radii of thermal sulfur ions is embedded into the thick current sheet with the thickness around one Jupiter radius, RJ. The vertical stress balance in the thin current sheet can be partially supported by the local maximum of the shear magnetic field. The amplitude of the corresponding field-aligned current density is comparable with the amplitude of the total current density. The drop of the plasma (electron) density across the thick current sheet is about 50-80% of the density peak value. We investigate horizontal (along the tail) distributions of magnetic field amplitudes B0 measured at the boundary of the current sheet and magnitudes of the normal component measured in the vicinity of the central region, Bn0. For r>50RJ both B0 and Bn0 vary with the radial distance r as ~r-1, and the ratio Bn0/B0~0.05-0.2 is almost constant along the tail (up to 120RJ). The amplitude of the current density jm0 and the plasma (electron) density (averaged across the current sheet) decrease with the same rate ~r-1. Thus, the current bulk velocity vD=jm0/e?100 km/s is almost constant along the tail. We compare properties of the Jovian magnetotail current sheet with the corresponding properties of current sheets observed in the Earth's magnetotail. Current sheet (CS) in the Jupiter magnetotail has been investigated. The magnetotail includes thin CS (thickness <0.25RJ) and thick CS (thickness ~1RJ). Thin CS thickness is only about two Larmor radius of thermal sulfur ions. Current density in thin CS cannot be described by diamagnetic currents.

  10. Derivation of ions bulk properties in the deep Jovian magnetotail beyond 200Rj

    NASA Astrophysics Data System (ADS)

    Nicolaou, G.; McComas, D. J.; Bagenal, F.; Elliott, H. A.

    2014-12-01

    New Horizons flew by Jupiter during 2007 and was the first spacecraft to obtain measurements in the deep Jovian magnetotail beyond 200 Rj. We analyze 50 spin-angle spectrograms obtained by Solar Wind Around Pluto (SWAP) instrument onboard New Horizons (NH) during the Jupiter encounter in order to derive the plasma ions bulk properties in this region. We excluded the observations in the Jovian boundary layer and the magnetosheath since they were analyzed in our previous studies. Here, we explain our methodology and we present our results. We show that the Jovian magnetotail has very diverse plasma populations. All of the bulk parameters of the observed plasma vary significantly within few hours. The plasma dynamic and thermal pressure varies by ~2 orders of magnitude during the magnetotail observations. In many subintervals, the non-tailward component of the flow direction is the major component. In some other cases, there is a clear tailward and very fast (~800 kms-1) flow of cold (~10eV) plasma. Finally, we isolate some subintervals to identify consistent changes in the plasma flow so we can then relate them to physical mechanisms that take place in the deep Jovian magnetotail.

  11. Jovian X-ray emissions

    NASA Technical Reports Server (NTRS)

    Waite, J. H.; Lewis, W. S.; Gladstone, G. R.; Fabian, A. C.; Brandt, W. N.

    1996-01-01

    The Einstein and Rosat observations of X-ray emissions from Jupiter are summarized. Jupiter's soft X-ray emission is observed to originate from the planet's auroral zones, and specifically, from its equatorial region. The processes responsible for these emissions are not established. The brightness distribution of the Jovian X-rays is characterized by the dependence on central meridian longitude and by north-south and morning-afternoon asymmetries. The X-rays observed during the impact of the comet Shoemaker-Levy 9 are believed to be impact-induced brightenings of the X-ray aurora.

  12. Dissipationless decay of Jovian jets

    NASA Astrophysics Data System (ADS)

    Pirraglia, J. A.

    1989-05-01

    IRIS data have been taken as the bases of windshear calculations whose results imply a decrease of the Jovian planet's zonal jets with altitude. The simplified dynamical model developed to furnish a mechanism accounting for the decay involves a highly truncated set of dissipationless equations simulating the upper-tropospheric and stratospheric flow. While the model's lower boundary is constrained as a latitudinally periodic set of alternating jets, the upper boundary constraint maintains a constant potential temperature. The small perturbations to which the imposed zonal jets are unstable grow and interact nonlinearly, generating a zonal flow that opposes the imposed one and thereby leading to the apparent decrease of the jets with altitude.

  13. The magnetic anomaly model of the Jovian magnetosphere - Predictions for Voyager

    NASA Technical Reports Server (NTRS)

    Dessler, A. J.; Vasyliunas, V. M.

    1979-01-01

    The magnetic anomaly model, in which the anomalously weak magnetic field region in the northern hemisphere of Jupiter influences the outer Jovian magnetosphere by one or more plasma interaction processes, has been put forth to account for the various observed Jovian magnetospheric phenomena that show evidence of Jovian longitudinal asymmetry or planetary spin periodicity. From this model, normalized by empirical fitting to Pioneer 10 and 11 flyby data and to ground-based radio data, a series of predictions are made that are subject to test by the forthcoming flybys of Jupiter by Voyagers 1 and 2. These predictions cover: (1) the longitude range and time intervals of enhanced interaction between Io (and possibly Europa) and Jupiter's ionosphere, (2) plasma, energetic particle, and magnetic field periodicities in the outer magnetosphere, and (3) the sub-spacecraft System III longitude and the time, modulo 10 hours, of the first and subsequent magnetopause crossings.

  14. Energetic oxygen and sulfur ions in the Jovian magnetosphere. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Gehrels, N.

    1981-01-01

    Observations of 1 to 20 MeV/nuc oxygen, sodium, and sulfur ions in the Jovian magnetosphere are reported. Measurements made by the cosmic ray subsystem on Voyager 1 and 2 were used to calculate abundances and energy spectra in the region from 5 to 20 Jovian radii. The phase space density of the oxygen ions calculated from the spectra has a positive radial gradient between 6 and 17 Jovian radii, indicating an inward diffusive flow. The diffusion coefficient upper limit at 9 Jovian radii is approximately 10 to the -5 power/s. This limit, combined with the analysis of Voyager plasma observations by Siscoe et al.1981, implies an upper limit to the mass loading rate near Io of approximately 10 to the 28th power ions/s. The energetic oxygen lifetime is within an order of magnitude of the strong pitch-angle diffusion lifetime in this region, with the largest total number of particles lost between 7.5 and 12.5 Jovian radii. It is shown that the losses are not due to geometric absorption by Io, absorption by dust grains, or energy loss in the plasma of the inner magnetosphere, and it is therefore postulated that the primary loss mechanism is pitch-angle scattering into the loss cone.

  15. Factors affecting ion kinetic temperature, number density, and containment time in the NASA Lewis bumpy-torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1977-01-01

    The degree of toroidal symmetry of the plasma, the number of midplane electrode rings, the configuration of electrode rings, and the location of the diagnostic instruments with respect to the electrode rings used to generate the plasma are discussed. Impurities were deliberately introduced into the plasma, and the effects of the impurity fraction on ion kinetic temperature and electron number density were observed. It is concluded that, if necessary precautions are taken, the plasma communicates extremely well along the magnetic field lines and displays a high degree of symmetry from sector to sector for a wide range of electrode ring configurations and operating conditions. Finally, some characteristic data taken under nonoptimized conditions are presented, which include the highest electron number density and the longest particle containment time (1.9 msec) observed. Also, evidence from a paired comparison test is presented which shows that the electric field acting along the minor radius of the toroidal plasma improves the plasma density and the calculated containment time more than an order of magnitude if the electric field points inward, relative to the values observed when it points (and pushes ions) radially outward.

  16. Jovian Lightning and Moonlit Clouds

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian lightning and moonlit clouds. These two images, taken 75 minutes apart, show lightning storms on the night side of Jupiter along with clouds dimly lit by moonlight from Io, Jupiter's closest moon. The images were taken in visible light and are displayed in shades of red. The images used an exposure time of about one minute, and were taken when the spacecraft was on the opposite side of Jupiter from the Earth and Sun. Bright storms are present at two latitudes in the left image, and at three latitudes in the right image. Each storm was made visible by multiple lightning strikes during the exposure. Other Galileo images were deliberately scanned from east to west in order to separate individual flashes. The images show that Jovian and terrestrial lightning storms have similar flash rates, but that Jovian lightning strikes are a few orders of magnitude brighter in visible light.

    The moonlight from Io allows the lightning storms to be correlated with visible cloud features. The latitude bands where the storms are seen seem to coincide with the 'disturbed regions' in daylight images, where short-lived chaotic motions push clouds to high altitudes, much like thunderstorms on Earth. The storms in these images are roughly one to two thousand kilometers across, while individual flashes appear hundreds of kilometer across. The lightning probably originates from the deep water cloud layer and illuminates a large region of the visible ammonia cloud layer from 100 kilometers below it.

    There are several small light and dark patches that are artifacts of data compression. North is at the top of the picture. The images span approximately 50 degrees in latitude and longitude. The lower edges of the images are aligned with the equator. The images were taken on October 5th and 6th, 1997 at a range of 6.6 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  17. Exploration of Jovian Magnetosphere and Trojan Asteroids by a Solar Power Sail Mission

    Microsoft Academic Search

    S. Sasaki; M. Fujimoto; Y. Kasaba; J. Kawaguchi; Y. Kawakatsu; O. Mori; T. Takashima; Y. Tsuda; H. Yano

    2009-01-01

    Europa Jupiter System Mission (EJSM) is a proposed international mission to explore Jupiter, Jovian satellites and environment. EJSM consists of (1) The Jupiter Europa Orbiter (JEO) by NASA, (2) the Jupiter Ganymede Orbiter (JGO) by ESA, (3) the Jupiter Magnetospheric Orbiter (JMO) studied by JAXA. (4) The Europa lander is also studied by Roscosmos. Together with plasma instruments on board

  18. Heavy ions from Galilean satellites and the centrifugal distortion of the Jovian magnetosphere

    Microsoft Academic Search

    T. W. Hill; F. C. Michel

    1976-01-01

    Heavy ions produced in the atmosphere of the Galilean satellites are a potentially significant source of plasma in the Jovian magnetosphere. Such ions will rapidly be accelerated to the corotation velocity, and the associated centrifugal force far exceeds that of gravity. Satellite ions are thus confined near the equator with a centrifugal scale height that depends linearly on their thermal

  19. Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas.

    PubMed

    Cazzaniga, C; Sundén, E Andersson; Binda, F; Croci, G; Ericsson, G; Giacomelli, L; Gorini, G; Griesmayer, E; Grosso, G; Kaveney, G; Nocente, M; Perelli Cippo, E; Rebai, M; Syme, B; Tardocchi, M

    2014-04-01

    First simultaneous measurements of deuterium-deuterium (DD) and deuterium-tritium neutrons from deuterium plasmas using a Single crystal Diamond Detector are presented in this paper. The measurements were performed at JET with a dedicated electronic chain that combined high count rate capabilities and high energy resolution. The deposited energy spectrum from DD neutrons was successfully reproduced by means of Monte Carlo calculations of the detector response function and simulations of neutron emission from the plasma, including background contributions. The reported results are of relevance for the development of compact neutron detectors with spectroscopy capabilities for installation in camera systems of present and future high power fusion experiments. PMID:24784606

  20. Local regulation of interchange turbulence in a dipole-confined plasma torus using current-collection feedbacka)

    NASA Astrophysics Data System (ADS)

    Roberts, T. M.; Mauel, M. E.; Worstell, M. W.

    2015-05-01

    Turbulence in plasma confined by a magnetic dipole is dominated by interchange fluctuations with complex dynamics and short spatial coherence. We report the first use of local current-collection feedback to modify, amplify, and suppress these fluctuations. The spatial extent of turbulence regulation is limited to a correlation length near the collector. Changing the gain and phase of collection results in power either extracted from or injected into the turbulence. The measured plasma response shows some agreement with calculations of the linear response of global interchange-like MHD and entropy modes to current-collection feedback.

  1. Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

    NASA Astrophysics Data System (ADS)

    Cazzaniga, C.; Sundén, E. Andersson; Binda, F.; Croci, G.; Ericsson, G.; Giacomelli, L.; Gorini, G.; Griesmayer, E.; Grosso, G.; Kaveney, G.; Nocente, M.; Cippo, E. Perelli; Rebai, M.; Syme, B.; Tardocchi, M.

    2014-04-01

    First simultaneous measurements of deuterium-deuterium (DD) and deuterium-tritium neutrons from deuterium plasmas using a Single crystal Diamond Detector are presented in this paper. The measurements were performed at JET with a dedicated electronic chain that combined high count rate capabilities and high energy resolution. The deposited energy spectrum from DD neutrons was successfully reproduced by means of Monte Carlo calculations of the detector response function and simulations of neutron emission from the plasma, including background contributions. The reported results are of relevance for the development of compact neutron detectors with spectroscopy capabilities for installation in camera systems of present and future high power fusion experiments.

  2. Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

    SciTech Connect

    Cazzaniga, C., E-mail: carlo.cazzaniga@mib.infn.it; Gorini, G.; Nocente, M. [Department of Physics “G. Occhialini,” University of Milano Bicocca, Piazza della Scienza 3, Milano (Italy) [Department of Physics “G. Occhialini,” University of Milano Bicocca, Piazza della Scienza 3, Milano (Italy); Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, via Roberto Cozzi 53, Milano (Italy); Sundén, E. Andersson; Binda, F.; Ericsson, G. [Department of Physics and Astronomy, EURATOM-VR Association, Uppsala University, Uppsala (Sweden)] [Department of Physics and Astronomy, EURATOM-VR Association, Uppsala University, Uppsala (Sweden); Croci, G.; Grosso, G.; Cippo, E. Perelli; Tardocchi, M. [Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, via Roberto Cozzi 53, Milano (Italy)] [Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, via Roberto Cozzi 53, Milano (Italy); Giacomelli, L.; Rebai, M. [Department of Physics “G. Occhialini,” University of Milano Bicocca, Piazza della Scienza 3, Milano (Italy)] [Department of Physics “G. Occhialini,” University of Milano Bicocca, Piazza della Scienza 3, Milano (Italy); Griesmayer, E. [Atominstitut, Vienna University of Technology (Austria)] [Atominstitut, Vienna University of Technology (Austria); Kaveney, G.; Syme, B. [Culham Centre for Fusion Energy, Culham OX143DB (United Kingdom)] [Culham Centre for Fusion Energy, Culham OX143DB (United Kingdom); Collaboration: JET-EFDA Contributors

    2014-04-15

    First simultaneous measurements of deuterium-deuterium (DD) and deuterium-tritium neutrons from deuterium plasmas using a Single crystal Diamond Detector are presented in this paper. The measurements were performed at JET with a dedicated electronic chain that combined high count rate capabilities and high energy resolution. The deposited energy spectrum from DD neutrons was successfully reproduced by means of Monte Carlo calculations of the detector response function and simulations of neutron emission from the plasma, including background contributions. The reported results are of relevance for the development of compact neutron detectors with spectroscopy capabilities for installation in camera systems of present and future high power fusion experiments.

  3. A model of Jovian magnetospheric diffusion incorporating precipitation-induced conductivity

    NASA Astrophysics Data System (ADS)

    Summers, D.; Thorne, R. M.; Mei, Yi.

    1988-02-01

    A steady-state model for the inward diffusion of energetic Jovian radiation belt ions driven by the outward interchange diffusion of cool ions from Io is presented. A new explicit form for the height-integrated Pedersen ionospheric conductivity is used which incorporates ion precipitation from the Jovian radiation belt. Qualitative agreement is found between model solutions for the energetic radiation belt ion density and reported observations. For all realistic solutions, the Iogenic ion density gradient over the Io plasma ramp is shown to be relatively insensitive to the model parameters and is less than about one half of the value obtained from Voyager 1 observations.

  4. Wake flowfields for Jovian probe

    NASA Technical Reports Server (NTRS)

    Engel, C. D.; Hair, L. M.

    1980-01-01

    The wake flow field developed by the Galileo probe as it enters the Jovian atmosphere was modeled. The wake produced by the probe is highly energetic, yielding both convective and radiative heat inputs to the base of the probe. A component mathematical model for the inviscid near and far wake, the viscous near and far wake, and near wake recirculation zone was developed. Equilibrium thermodynamics were used for both the ablation and atmospheric species. Flow fields for three entry conditions were calculated. The near viscous wave was found to exhibit a variable axial pressure distribution with the neck pressure approximately three times the base pressure. Peak wake flow field temperatures were found to be in proportion to forebody post shock temperatures.

  5. Integration of Microsoft Windows Applications with MDSplus Data Acquisition on the National Spherical Torus Experiment at the Princeton Plasma Physics Laboratory

    SciTech Connect

    Dana M. Mastrovito

    2002-03-14

    Data acquisition on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory (PPPL) has increasingly involved the use of Personal Computers (PC's) and specially developed ''turn-key'' hardware and software systems to control diagnostics. Interaction with these proprietary software packages is accomplished through use of Visual Basic, or Visual C++ and COM (Component Object Model) technology. COM is a software architecture that allows the components made by different software vendors to be combined into a variety of applications. This technology is particularly well suited to these systems because of its programming language independence, standards for function calling between components, and ability to transparently reference remote processes. COM objects make possible the creation of acquisition software that can control the experimental parameters of both the hardware and software. Synchronization of these applications for diagnostics, such as CCD camer as and residual gas analyzers, with the rest of the experiment event cycle at PPPL has been made possible by utilization of the MDSplus libraries for Windows. Instead of transferring large data files to remote disk space, Windows MDSplus events and I/O functions allow us to put raw data into MDSplus directly from IDL for Windows and Visual Basic. The combination of COM technology and the MDSplus libraries for Windows provide the tools for many new possibilities in versatile acquisition applications and future diagnostics.

  6. Jovian Temperatures--Highest Resolution

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is the highest resolution image ever recorded of Jupiter's temperature field. It was obtained by NASA's Galileo mission, with its Photopolarimeter-Radiometer (PPR) experiment, during the seventh of its 10 orbits around Jupiter to date, in the vicinity of Jupiter's Great Red Spot. This image, shown on the bottom panel, indicates the forces powering Jovian winds, and differentiates between areas of strongest upwelling and downwelling winds in the upper part of the atmosphere where winds are strong. For reference, the upper panel shows the visible clouds in a Hubble Space Telescope Planetary Camera color composite image of the same part of the planet taken within 10 hours of the PPR observation.

    Many of Galileo's atmospheric observations targeted specific Jovian cloud features, including the Great Red Spot. It is the planet's coldest region, indicating that winds are upwelling and forcing air to expand outward over its entire visible extent. The edges of the cold inner region of the Great Red Spot are close to the PPR's 1800-kilometer (1100-mile) spatial resolution. The largest temperature gradient is also seen between the cold 'inner' Great Red Spot and a region some 5000 kilometers (3000 miles) south which is more than 10 degrees warmer. This implies a strong eastward jet, consistent with cloud-tracked winds.

    The southern central portion of the Great Red Spot is not as cold as the rest of the feature. This is consistent with the winds inside the Great Red Spot being more complicated than a simple counterclockwise rotation around the center.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  7. ALBEDOS OF SMALL JOVIAN TROJANS

    SciTech Connect

    Fernandez, Yanga R. [Department of Physics, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816-2385 (United States); Jewitt, David [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Ziffer, Julie E. [Department of Physics, University of Southern Maine, 96 Falmouth Street, Portland, ME 04104-9300 (United States)

    2009-07-15

    We present thermal observations of 44 Jovian Trojan asteroids with diameters D ranging from 5 to 24 km. All objects were observed at a wavelength of 24 {mu}m with the Spitzer Space Telescope. Measurements of the thermal emission and of scattered optical light, mostly from the University of Hawaii 2.2 m Telescope, together allow us to constrain the diameter and geometric albedo of each body. We find that the median R-band albedo of these small Jovian Trojans is about 0.12, much higher than that of 'large' Trojans with D>57 km (0.04). Also the range of albedos among the small Trojans is wider. The small Trojans' higher albedos are also glaringly different from those of cometary nuclei, which match our sample Trojans in diameter, however, they roughly match the spread of albedos among (much larger) Centaurs and trans-Neptunian objects. We attribute the Trojan albedos to an evolutionary effect: the small Trojans are more likely to be collisional fragments and so their surfaces would be younger. A younger surface means less cumulative exposure to the space environment, which suggests that their surfaces would not be as dark as those of the large, primordial Trojans. In support of this hypothesis is a statistically significant correlation of higher albedo with smaller diameter in our sample alone and in a sample that includes the larger Trojans. This correlation of albedo and radius implies that the true size distribution of small Trojans is shallower than the visible magnitude distribution alone would suggest, and that there are approximately half the Trojans with D>1 km than previously estimated.

  8. ConcepTest: Jovian Planet Characteristics

    NSDL National Science Digital Library

    The characteristics of four planets are listed below. Which planet is most likely to be classified as Jovian? a. Mainly rocky, volcanism, low gravity. b. Mainly rocky, no volcanism, high gravity. c. Mainly gaseous, ...

  9. Flow and shear behavior in the edge and scrape-off layer of L-mode plasmas in National Spherical Torus Experiment

    DOE PAGESBeta

    Sechrest, Y. [Univ. of Colorado, Boulder, CO (United States); Munsat, T. [Univ. of Colorado, Boulder, CO (United States); D’Ippolito, D. A. [Lodestar Research Corp., Boulder, CO (United States); Maqueda, R. J. [Princeton Plasma Physics Lab., NJ (United States); Myra, J. R. [Lodestar Research Corp., Boulder, CO (United States); Russell, D. [Lodestar Research Corp., Boulder, CO (United States); Zweben, S. J. [Princeton Plasma Physics Lab., NJ (United States)

    2011-01-10

    Fluctuations in the edge and scrape-off layer (SOL) of L-mode plasmas in the National Spherical Torus Experiment (NSTX) [S. M. Kaye et al.,Phys. Plasmas 8, 1977 (2001)] as observed by the gas puff imaging (GPI) diagnostic are studied. Calculation of local, time resolved velocity maps using the Hybrid Optical Flow and Pattern Matching Velocimetry (HOP-V) code enables analysis of turbulent flow and shear behavior. Periodic reversals in the direction of the poloidal flow near the separatrix are observed. Also, poloidal velocities and their radial shearing rate are found to be well correlated with the fraction of D? light contained in the SOL, which acts as a measure of turbulent bursts. The spectra of GPI intensity and poloidal velocity both have a strong feature near 3 kHz, which appears to correspond with turbulent bursts. This mode exhibits a poloidal structure with poloidal wavenumber of 7.7 m-1 for GPI intensity and 3.4 m-1 for poloidal velocity, and the poloidal velocity fluctuations near 3 kHz remain coherent over length scales in excess of the turbulent scales. Furthermore, recent SOL Turbulence (SOLT) simulations find a parameter regime that exhibits periodic bursty transport and shares many qualitative similarities with the experimental data. Strong correlations between the shearing rate and the turbulent bursts are observed for time periods of ~ 2 ms, but the relationship is complicated by several factors. Finally, measurements of the radial profiles of the Reynolds shear stresses are reported. These radial profiles exhibit many similarities for several shots, and a region with positive radial gradient is seen to be coincident with local flow shear.

  10. Flow and shear behavior in the edge and scrape-off layer of L-mode plasmas in National Spherical Torus Experiment

    SciTech Connect

    Sechrest, Y. [Univ. of Colorado, Boulder, CO (United States); Munsat, T. [Univ. of Colorado, Boulder, CO (United States); D’Ippolito, D. A. [Lodestar Research Corp., Boulder, CO (United States); Maqueda, R. J. [Princeton Plasma Physics Lab., NJ (United States); Myra, J. R. [Lodestar Research Corp., Boulder, CO (United States); Russell, D. [Lodestar Research Corp., Boulder, CO (United States); Zweben, S. J. [Princeton Plasma Physics Lab., NJ (United States)

    2011-01-10

    Fluctuations in the edge and scrape-off layer (SOL) of L-mode plasmas in the National Spherical Torus Experiment (NSTX) [S. M. Kaye et al.,Phys. Plasmas 8, 1977 (2001)] as observed by the gas puff imaging (GPI) diagnostic are studied. Calculation of local, time resolved velocity maps using the Hybrid Optical Flow and Pattern Matching Velocimetry (HOP-V) code enables analysis of turbulent flow and shear behavior. Periodic reversals in the direction of the poloidal flow near the separatrix are observed. Also, poloidal velocities and their radial shearing rate are found to be well correlated with the fraction of D? light contained in the SOL, which acts as a measure of turbulent bursts. The spectra of GPI intensity and poloidal velocity both have a strong feature near 3 kHz, which appears to correspond with turbulent bursts. This mode exhibits a poloidal structure with poloidal wavenumber of 7.7 m-1 for GPI intensity and 3.4 m-1 for poloidal velocity, and the poloidal velocity fluctuations near 3 kHz remain coherent over length scales in excess of the turbulent scales. Furthermore, recent SOL Turbulence (SOLT) simulations find a parameter regime that exhibits periodic bursty transport and shares many qualitative similarities with the experimental data. Strong correlations between the shearing rate and the turbulent bursts are observed for time periods of ~ 2 ms, but the relationship is complicated by several factors. Finally, measurements of the radial profiles of the Reynolds shear stresses are reported. These radial profiles exhibit many similarities for several shots, and a region with positive radial gradient is seen to be coincident with local flow shear.

  11. Flow and shear behavior in the edge and scrape-off layer of L-mode plasmas in National Spherical Torus Experiment

    DOE PAGESBeta

    Sechrest, Y.; Munsat, T.; D’Ippolito, D. A.; Maqueda, R. J.; Myra, J. R.; Russell, D.; Zweben, S. J.

    2011-01-10

    Fluctuations in the edge and scrape-off layer (SOL) of L-mode plasmas in the National Spherical Torus Experiment (NSTX) [S. M. Kaye et al.,Phys. Plasmas 8, 1977 (2001)] as observed by the gas puff imaging (GPI) diagnostic are studied. Calculation of local, time resolved velocity maps using the Hybrid Optical Flow and Pattern Matching Velocimetry (HOP-V) code enables analysis of turbulent flow and shear behavior. Periodic reversals in the direction of the poloidal flow near the separatrix are observed. Also, poloidal velocities and their radial shearing rate are found to be well correlated with the fraction of D? light contained inmore »the SOL, which acts as a measure of turbulent bursts. The spectra of GPI intensity and poloidal velocity both have a strong feature near 3 kHz, which appears to correspond with turbulent bursts. This mode exhibits a poloidal structure with poloidal wavenumber of 7.7 m-1 for GPI intensity and 3.4 m-1 for poloidal velocity, and the poloidal velocity fluctuations near 3 kHz remain coherent over length scales in excess of the turbulent scales. Furthermore, recent SOL Turbulence (SOLT) simulations find a parameter regime that exhibits periodic bursty transport and shares many qualitative similarities with the experimental data. Strong correlations between the shearing rate and the turbulent bursts are observed for time periods of ~ 2 ms, but the relationship is complicated by several factors. Finally, measurements of the radial profiles of the Reynolds shear stresses are reported. These radial profiles exhibit many similarities for several shots, and a region with positive radial gradient is seen to be coincident with local flow shear.« less

  12. Low-frequency fluctuation spectra and associated particle transport in the NASA Lewis bumpy-torus plasma

    NASA Technical Reports Server (NTRS)

    Singh, C. M.; Krawczonek, W. M.; Roth, J. R.; Hong, J. Y.; Kim, Y. C.; Powers, E. J.

    1978-01-01

    The strong radial electric field associated with the Penning discharge and the strong toroidal magnetic field give rise to a diversity of E/B phenomena, such as rotating waves and spokes, which in turn manifest themselves as space-time fluctuations of the plasma density and potential. Work is done to further understand the nature and origin of the fluctuations and their connection with fluctuation-induced transport. The approach is to monitor the density and potential fluctuations; to digitize the data; and to generate, with the aid of a computer, various spectral properties by means of the fast fourier transform. Of particular interest is the computer-generated transport spectrum that indicates in a quantitative way which fluctuation spectral components contribute to transport and which do not. All experimental measurements of the spectral characteristics of the plasma are given in absolute units rather than as relative values. Preliminary measurements of the transport spectrum of the ion population are given, and it is shown that the fluctuation-induced transport is in order-of-magnitude agreement with that inferred from the steady state current flowing to the electrodes that generate the plasma.

  13. Scanning microwave interferometer for ELMO bumpy torus

    SciTech Connect

    Uckan, T.

    1983-10-01

    A simple 4-mm scanning microwave interferometer has been developed and employed for electron density profile measurements on the ELMO bumpy torus (EBT). By making use of a pair of horizontally moving 45/sup 0/ mirrors that are located at the top and bottom of the plasma volume, the system avoids the deleterious effects of plasma sputtering and wall material flaking, since the microwave transmission and receiving horns do not view the plasma directly.

  14. Torus knots as Hopfions

    E-print Network

    Kobayashi, Michikazu

    2014-01-01

    We present a direct connection between torus knots and Hopfions by finding stable and static solutions of the extended Faddeev-Skyrme model with a ferromagnetic potential term. (P,Q)--torus knots consisting of |Q| sine-Gordon kink strings twisted P/Q times into the poloidal cycle along the toroidal cycle on a toroidal domain wall carry the Hopf charge PQ, which demonstrates that Hopfions can be further classified according to torus knot type.

  15. Resistive Drift Waves in a Bumpy Torus

    SciTech Connect

    J.L.V. Lewandowski

    2004-01-12

    A computational study of resistive drift waves in the edge plasma of a bumpy torus is presented. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.

  16. Cassini Imaging Observations of the Jovian Ring

    E-print Network

    Throop, Henry

    Cassini Imaging Observations of the Jovian Ring ISSI Dusty Rings Workshop June 20, 2005 / Berne #12;Cassini ISS Imaging Summary 1200 images of main ring ­ No halo or gossamer observations Mostly short > 2x average. Galileo `checkerboard' features of Ockert- Bell not seen due to lower Cassini

  17. Measurements of the Jovian radiation belts

    Microsoft Academic Search

    R. W. Fillius; C. E. McIlwain

    1974-01-01

    The University of California at San Diego trapped radiation detector measured proton and electron fluxes, angular distributions, and energy spectra throughout the Pioneer 10 flyby of Jupiter last December. Here the instrumentation and calibrations are described, and good values for particle fluxes in the inner and outer regions are presented. The major features of the Jovian radiation belts are described,

  18. A Global Magnetohydrodynamic Model of Jovian Magnetosphere

    NASA Technical Reports Server (NTRS)

    Walker, Raymond J.; Sharber, James (Technical Monitor)

    2001-01-01

    The goal of this project was to develop a new global magnetohydrodynamic model of the interaction of the Jovian magnetosphere with the solar wind. Observations from 28 orbits of Jupiter by Galileo along with those from previous spacecraft at Jupiter, Pioneer 10 and 11, Voyager I and 2 and Ulysses, have revealed that the Jovian magnetosphere is a vast, complicated system. The Jovian aurora also has been monitored for several years. Like auroral observations at Earth, these measurements provide us with a global picture of magnetospheric dynamics. Despite this wide range of observations, we have limited quantitative understanding of the Jovian magnetosphere and how it interacts with the solar wind. For the past several years we have been working toward a quantitative understanding of the Jovian magnetosphere and its interaction with the solar wind by employing global magnetohydrodynamic simulations to model the magnetosphere. Our model has been an explicit MHD code (previously used to model the Earth's magnetosphere) to study Jupiter's magnetosphere. We continue to obtain important insights with this code, but it suffers from some severe limitations. In particular with this code we are limited to considering the region outside of 15RJ, with cell sizes of about 1.5R(sub J). The problem arises because of the presence of widely separated time scales throughout the magnetosphere. The numerical stability criterion for explicit MHD codes is the CFL limit and is given by C(sub max)(Delta)t/(Delta)x less than 1 where C(sub max) is the maximum group velocity in a given cell, (Delta)x is the grid spacing and (Delta)t is the time step. If the maximum wave velocity is C(sub w) and the flow speed is C(sub f), C(sub max) = C(sub w) + C(sub f). Near Jupiter the Alfven wave speed becomes very large (it approaches the speed of light at one Jovian radius). Operating with this time step makes the calculation essentially intractable. Therefore under this funding we have been designing a new MHD model that will be able to compute solutions in the wide parameter regime of the Jovian magnetosphere.

  19. New Horizons Plasma Observations of Jupiter's Magnetotail to >2500 RJ

    Microsoft Academic Search

    D. J. McComas

    2007-01-01

    (*On behalf of the New Horizons Plasma Science Team.) Observations from the New Horizons spacecraft as it traversed down the jovian magnetotail to >2500 jovian radii (RJ) reveal a remarkable diversity of plasma populations and structures. At ~~100 RJ the ions evolved from a hot plasma disk distribution to slower flows down the tail that persisted and became increasingly variable

  20. Simulation of Plasma Interaction with Io's Atmosphere

    NASA Astrophysics Data System (ADS)

    Moore, Chris H.; Deng, Hao; Goldstein, David B.; Levin, Deborah; Varghese, Philip L.; Trafton, Laurence M.; Stewart, Bénédicte D.; Walker, Andrew C.

    2011-05-01

    One dimensional Direct Simulation Monte Carlo (DSMC) simulations are used to examine the interaction of the jovian plasma torus with Io's sublimation atmosphere. The hot plasma sweeps past Io at ˜57 km/s due to the external Jovian magnetic and corotational electric fields and the resultant energetic collisions both heat and dissociate the neutral gas creating an inflated, mixed atmosphere of SO2 and its daughter products. The vertical structure and composition of the atmosphere is important for understanding Io's mass loading of the plasma torus, electron excited aurora, and Io's global gas dynamics. Our 1D simulations above a fixed location on the surface of Io allows the O+ and S+ ions to drift down into the domain where they then undergo elastic and charge exchange collisions with the neutral gas. Each electron's position is determined by the motion of a corresponding ion; however, the electrons retain their own velocity components which are then used during elastic, ionization, and excitation collisions with the neutral gas. Charge exchange creates fast neutral O and S atoms. Molecular Dynamic/Quasi-Classical Trajectory (MD/QCT) calculations are used to generate total and reaction cross sections for energetic O+SO2 collisions [1] as well as for O+O2 collisions. In addition, the model accounts for photo-dissociation assuming the atmosphere is optically thin. Our previous plasma heating model (without chemistry) agrees well with the vertical structure of the current model at lower altitudes where the gas is collisional; however, at high altitudes (>100 km) significant differences among the models appear. The current model's constant E and B fields results in reacceleration of the ions and electrons to a constant E×B drift velocity towards the surface after collisions with the neutral gas and, while the results are an upper limit on the plasma interaction strength, the results indicate that joule heating is significant, causing large changes in the vertical structure of the atmosphere. Plasma heating of, not momentum transfer to, the atmosphere dominates even for radially inward plasma flows resulting in a hot, inflated atmosphere. The scale heights for the various species were found to be a competition between the hydrodynamic scale height based on the gas constant (for the mixture if collisional) and the production rate from dissociation of SO2 which depends on the local SO2 density and available plasma energy at that altitude.

  1. PPPL-3445 PPPL-3445 National Spherical Torus Experiment (NSTX)

    E-print Network

    to the plasma. The NBI heating system and associated NBI based diagnostics such as the CHERS will be operational and divertors; in a low-aspect-ratio (spherical) torus as a plasma confinement innovation. These principles on the U.S. Department of Energy's Princeton Plasma Physics Laboratory Publications and Reports web site

  2. Exploration of Jovian Magnetosphere and Trojan Asteroids by a Solar Power Sail Mission

    NASA Astrophysics Data System (ADS)

    Sasaki, S.; Fujimoto, M.; Kasaba, Y.; Kawaguchi, J.; Kawakatsu, Y.; Mori, O.; Takashima, T.; Tsuda, Y.; Yano, H.; Jupiter Exploration Working Group

    2009-04-01

    Europa Jupiter System Mission (EJSM) is a proposed international mission to explore Jupiter, Jovian satellites and environment. EJSM consists of (1) The Jupiter Europa Orbiter (JEO) by NASA, (2) the Jupiter Ganymede Orbiter (JGO) by ESA, (3) the Jupiter Magnetospheric Orbiter (JMO) studied by JAXA. (4) The Europa lander is also studied by Roscosmos. Together with plasma instruments on board JEO and JGO, JMO will investigate the fast and huge rotating magnetosphere to clarify the energy procurement from Jovian rotation to the magnetosphere, to clarify the interaction between the solar wind the magnetosphere. JMO will clarify the characteristics of the strongest accelerator in the solar system. JMO will investigate the role of Io as a source of heavy ions in the magnetosphere. Proposed instruments on board JMO are magnetometers, low-energy plasma spectrometers, medium energy particle detectors, energetic particle detectors, electric field / plasma wave instruments, a dust detector, an ENA imager, and EUV spectrometer. JAXA is studying solar power sail for deep space explorations following the successful ion engine mission Hayabusa. This is not only solar sail (photon propulsion) but also include very efficient ion engines where electric power is produced solar panels within the sail. Currently we are studying a mission to Jupiter and one (or two) of Trojan asteroids, which are primitive bodies with information of the early solar system as well as raw solid materials of Jovian system. As the main spacecraft flies by Jupiter heading for an asteroid, it will deploy JMO spinner around Jupiter.

  3. Computation of Three Dimensional Tokamak and Spherical Torus Equilibria

    SciTech Connect

    Park, Jong-kyu; Boozer, Allen H.; Glasser, Alan H.

    2007-05-07

    A nominally axisymmetric plasma con?guration, such as a tokamak or a spherical torus, is highly sensitive to non-axisymmetric magnetic perturbations due to currents outside of the plasma. The high sensitivity means that the primary interest is in the response of the plasma to very small perturbations, | ?(over) ?/?(over)? | ? 10–2 to 10–4, which can be calculated using the theory of perturbed equilibria. The Ideal Perturbed Equilibrium Code (IPEC) is described and applied to the study of the plasma response in a spherical torus to such external perturbations.

  4. Io revealed in the Jovian dust streams

    E-print Network

    Graps, A L; Krüger, H; Horányi, M; Svedhem, H; Graps, Amara Lynn; Gr\\"un, Eberhard; Kr\\"uger, Harald; Hor\\'anyi, Mih\\'a{\\l}y

    2002-01-01

    The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same direction from a source in the Jovian system. Since their discovery in 1992, they have been observed by three spacecraft: Ulysses, Galileo and Cassini. The source of the Jovian dust streams is dust from Io's volcanoes. The charged and traveling dust stream particles have particular signatures in frequency space and in real space. The frequency-transformed Galileo dust stream measurements show different signatures, varying orbit-to-orbit during Galileo's first 29 orbits around Jupiter. Time-frequency analysis demonstrates that Io is a localized source of charged dust particles. Aspects of the particles' dynamics can be seen in the December-2000 joint Galileo-Cassini dust stream measurements. To match the travel times, the smallest dust particles could have the following range of parameters: radius: 6nm, density: 1.35-1.75gr/cm$^3$, sulfur charging conditions, which produce dust stream speeds: 220|450km/sec (Galileo...

  5. The Jovian Auroral Distributions Experiment (JADE) on the Juno Mission to Jupiter

    NASA Astrophysics Data System (ADS)

    McComas, D. J.; Alexander, N.; Allegrini, F.; Bagenal, F.; Beebe, C.; Clark, G.; Crary, F.; Desai, M. I.; De Los Santos, A.; Demkee, D.; Dickinson, J.; Everett, D.; Finley, T.; Gribanova, A.; Hill, R.; Johnson, J.; Kofoed, C.; Loeffler, C.; Louarn, P.; Maple, M.; Mills, W.; Pollock, C.; Reno, M.; Rodriguez, B.; Rouzaud, J.; Santos-Costa, D.; Valek, P.; Weidner, S.; Wilson, P.; Wilson, R. J.; White, D.

    2013-05-01

    The Jovian Auroral Distributions Experiment (JADE) on Juno provides the critical in situ measurements of electrons and ions needed to understand the plasma energy particles and processes that fill the Jovian magnetosphere and ultimately produce its strong aurora. JADE is an instrument suite that includes three essentially identical electron sensors (JADE-Es), a single ion sensor (JADE-I), and a highly capable Electronics Box (EBox) that resides in the Juno Radiation Vault and provides all necessary control, low and high voltages, and computing support for the four sensors. The three JADE-Es are arrayed 120? apart around the Juno spacecraft to measure complete electron distributions from ˜0.1 to 100 keV and provide detailed electron pitch-angle distributions at a 1 s cadence, independent of spacecraft spin phase. JADE-I measures ions from ˜5 eV to ˜50 keV over an instantaneous field of view of 270?×90? in 4 s and makes observations over all directions in space each 30 s rotation of the Juno spacecraft. JADE-I also provides ion composition measurements from 1 to 50 amu with m/?m˜2.5, which is sufficient to separate the heavy and light ions, as well as O+ vs S+, in the Jovian magnetosphere. All four sensors were extensively tested and calibrated in specialized facilities, ensuring excellent on-orbit observations at Jupiter. This paper documents the JADE design, construction, calibration, and planned science operations, data processing, and data products. Finally, the Appendix describes the Southwest Research Institute [SwRI] electron calibration facility, which was developed and used for all JADE-E calibrations. Collectively, JADE provides remarkably broad and detailed measurements of the Jovian auroral region and magnetospheric plasmas, which will surely revolutionize our understanding of these important and complex regions.

  6. Code to generate Torus public void InitTorus()

    E-print Network

    Gordon, Scott

    [ring*(torusPrecision+1)+i]. setS(2.0f*(float)ring/(float)torusPrecision); vertices[ring*(torusPrecision+1)+i].setT(vertices[i].getT()); Vector3D str = vertices[i].getSTangent(); Vector3D stry = myRotateY(str, rotAmt); vertices

  7. Impact of Plasma Chemistry on Io's Atmosphere

    NASA Astrophysics Data System (ADS)

    Moore, Chris H.; Deng, H.; Goldstein, D. B.; Levin, D.; Varghese, P. L.; Trafton, L. M.; Walker, A. C.; Stewart, B. D.

    2010-10-01

    We present results of an investigation of the jovian plasma torus’ interaction with Io's sublimation atmosphere using the direct simulation Monte Carlo (DSMC) method which is appropriate for solving rarefied flows such as Io's atmosphere. Accurate simulation of Io's atmosphere is critical for modeling the supply of material to the torus and understanding the morphology and intensity of the electron excited aurora on Io. The plasma sweeps past Io at 57 km/s and the resultant energetic collisions with Io's neutral atmosphere create an inflated, mixed atmosphere of SO2 and its daughter products. In the present work, the plasma interaction is modeled by a flux of ions and electrons which flow around and through Io's atmosphere along pre-computed perturbed magnetic field lines. Since the Debye length is everywhere much less than the size of the DSMC computational cells (which scale with the neutral mean free path), we assume the plasma is quasi-neutral. A two time-step method is used in which the neutrals move and then are stationary while the ions and electrons move with a much smaller time-step. Ions can undergo non-reactive collisions and charge exchange collisions with the neutral species. Fast neutrals produced via charge exchange have sufficient energy to dissociate the neutral molecular species; these interaction cross sections have been computed using MD/QCT simulations. The electron interactions with the neutral species are functions of the collision energy and are based on measured reaction cross sections (elastic, excitation, ionization, and dissociation). The effect of the plasma on the circumplanetary winds, the escape rate of neutrals from Io, and the composition and structure of Io's atmosphere is investigated and compared with previous continuum simulations by Smyth and Wong. Future work will investigate the resultant auroral emissions and their implications on volcanic activity and the upstream electron temperature.

  8. Studies of accelerated compact toruses

    SciTech Connect

    Hartman, C.W.; Eddleman, J.; Hammer, J.H.

    1983-01-04

    In an earlier publication we considered acceleration of plasma rings (Compact Torus). Several possible accelerator configurations were suggested and the possibility of focusing the accelerated rings was discussed. In this paper we consider one scheme, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focusing) during acceleration. Because the allowable acceleration force, F/sub a/ = kappaU/sub m//R where (kappa < 1), increases as R/sup -2/, the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case, however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency.

  9. Location and shape of the Jovian magnetopause and bow shock

    Microsoft Academic Search

    D. E. Huddleston; C. T. Russell; M. G. Kivelson; K. K. Khurana; L. Bennett

    1998-01-01

    Following Galileo's arrival at Jupiter in fall 1995, a total of six spacecraft have now sampled the Jovian magnetosphere. Using these data sets to investigate the average location and shape of the Jovian boundaries, we fit ellipse profiles to the observations, allowing for the disk-like shape of the magnetosphere and taking account of variable solar wind pressure. We find that

  10. Millimeter-wave spectra of the Jovian planets

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Steffes, Paul G.

    1991-01-01

    The millimeter wave portion of the electromagnetic spectrum is critical for understanding the subcloud atmospheric structure of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune). This research utilizes a combination of laboratory measurements, computer modeling, and radio astronomical observation in order to obtain a better understanding of the millimeter-wave spectra of the Jovian planets. The pressure broadened absorption from gaseous ammonia (NH3) and hydrogen sulfide (H2S) was measured in the laboratory under simulated conditions for the Jovian atmospheres. Researchers developed new formalisms for computing the absorptivity of gaseous NH3 and H2S based on their laboratory measurements. They developed a radiative transfer and thermochemical model to predict the abundance and distribution of absorbing constituents in the Jovian atmospheres. They used the model to compute the millimeter wave emission from the Jovian planets.

  11. Jovian modulation of interplanetary electrons as observed with Voyagers 1 and 2

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.; Mcdonald, F. B.; Trainor, J. H.

    1982-01-01

    The release of magnetospheric electrons from Jupiter into interplanetary space is modulated by the Jovian rotation period. The Voyager 1 and 2 observations showed that the modulation period agrees on the average with the synodic period of Jupiter (9h 55m 33.12s), but over intervals of weeks it can differ from the synodic period by several minutes. The lack of exact synchronization is attributed to changes of the plasma population in the Jovian magnetosphere. The Jovian modulation appears to be a persistent feature of the interaction between the solar wind and the magnetosphere and the disappearance of the modulation away from Jupiter is attributed to interplanetary propagation conditions. This leads to the following limits on the diffuse coefficient for interplanetary electrons: kappa perpendicular is or = 8 x 10 to the 19th power sq cm/s and kappa parallel is or = 10 to the 21st power sq cm/s. Modulation was still detectable at 3.8 A.U. behind Jupiter in the far magnetotail. This requires a mean free path in the tail 0.75 A.U. and good field connection along the tail to Jupiter.

  12. A dawn to dusk electric field in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.; Ip, W. I.

    1983-01-01

    It is shown that if Io-injected plasma is lost via a planetary wind-fixed Birkeland current system may result. This is due to the fact that the azimuthal centrifugal current flows across a density gradient produced by the loss of plasma through the planetary wind in the tail. The divergent centrifugal current is connected to field-aligned Birkeland currents which flow into the ionosphere at dawn and out of it at dusk. The closure currents in the ionosphere require a dawn to dusk electric field which at the orbit of Io is estimated to have a strength of 0.2 mV/m. However, the values of crucial parameters are not well known and the field at Io's orbit may well be significantly larger. Independent estimates derived from the local time asymmetry of the torus UV emission indicate a field of 1.5 mV/m.

  13. Evidence for global electron transportation into the jovian inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Yoshioka, K.; Murakami, G.; Yamazaki, A.; Tsuchiya, F.; Kimura, T.; Kagitani, M.; Sakanoi, T.; Uemizu, K.; Kasaba, Y.; Yoshikawa, I.; Fujimoto, M.

    2014-09-01

    Jupiter’s magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves.

  14. New Attempt at Detecting the Jovian Oscillations

    NASA Astrophysics Data System (ADS)

    Mosser, B.; Maillard, J. P.; Mékarnia, D.

    2000-03-01

    This paper reports seismic observations of Jupiter conducted in August 1996 with the Fourier Transform Spectrometer based at the CFH telescope, used as an accelerometer. With this instrument, the jovian velocity field was measured for the first time with an absolute velocity calibration. The noise in the Fourier spectrum reaches 4 cm s -1?Hz -1/2. A dominating source of noise, identified as due to spurious velocity signals induced by the guiding errors on the rapid rotating planet, as well as a poor window function, has precluded the possible direct identification of jovian modes. However, there is strong evidence in the data for an oscillation characteristic frequency (or large splitting) ? 0, at 142±3?Hz, which confirms a low value of this parameter. Furthermore, the measurement of this parameter with a constant value in different frequency ranges along the whole Fourier spectrum seems to indicate a very small planetary core. The modes amplitude is inferred not to exceed 0.6 m s -1 in the 1- to 3.1-mHz frequency range.

  15. A theory of Jovian decameter radiation

    NASA Astrophysics Data System (ADS)

    Goldstein, M. L.; Sharma, R. R.; Ben-Ari, M.; Eviatar, A.; Papadopoulos, K.

    1983-02-01

    A theory of the Jovian decameter radiation is presented based on the assumed existence of beams of energetic electrons in the inner Jovian magnetosphere. Beam-like electron distributions are shown to be unstable to the growth of both upper hybrid and lower hybrid electrostatic waves. The upconversion of these waves to fast extraordinary mode electromagnetic radiation is calculated by using a fluid model. Two possibilities are considered. First, a random phase approximation is made which leads to a very conservative estimate of intensity that can be expected in decameter radiation. The alternative possibility is also considered, viz, that the upconversion process is coherent. A comparison of both processes suggests that an incoherent interaction may be adequate to account for the observed intensity of decametric radiation, except perhaps near the peak of the spectrum (8 MHz). The coherent process is intrinsically more efficient and can easily produce the observed intensity near 8 MHz if only 0.01% of the energy in the beam is converted to electrostatic energy.

  16. JUICE: a European mission to the Jovian system

    NASA Astrophysics Data System (ADS)

    Titov, Dmitrij; Dougherty, Michele K.; Wahlund, Jan-Erik; Barabash, Stas; Palumbo, Pasquale; Iess, Luciano; Piccioni, Giuseppe; Hussmann, Hauke; Langevin, Yves; Jaumann, Ralf; Altobelli, Nicolas; Fletcher, Leigh; Gurvits, Leonid; Gladstone, Randy; Erd, Christian; Hartogh, Paul; Bruzz, Lorenzo

    JUpiter ICy moons Explorer (JUICE) will perform detailed investigations of Jupiter and its system with particular emphasis on Ganymede as a planetary body and potential habitat. The overarching theme for JUICE is: The emergence of habitable worlds around gas giants. At Ganymede, the mission will characterize in detail the ocean layers; provide topographical, geological and compositional mapping of the surface; study the physical properties of the icy crusts; characterize the internal mass distribution, investigate the exosphere; study Ganymede’s intrinsic magnetic field and its interactions with the Jovian magnetosphere. For Europa, the focus will be on the non-ice chemistry, understanding the formation of surface features and subsurface sounding of the icy crust over recently active regions. Callisto will be explored as a witness of the early solar system. JUICE will perform a multidisciplinary investigation of the Jupiter system as an archetype for gas giants. The circulation, meteorology, chemistry and structure of the Jovian atmosphere will be studied from the cloud tops to the thermosphere. The focus in Jupiter’s magnetosphere will include an investigation of the three dimensional properties of the magnetodisc and in-depth study of the coupling processes within the magnetosphere, ionosphere and thermosphere. Aurora and radio emissions will be elucidated. JUICE will study the moons’ interactions with the magnetosphere, gravitational coupling and long-term tidal evolution of the Galilean satellites. JUICE highly capable scientific payload includes 10 state-of-the-art instruments onboard the spacecraft plus one experiment that uses the spacecraft telecommunication system with ground-based radio telescopes. The remote sensing package includes a high-resolution multi-band visible imager (JANUS) and spectro-imaging capabilities from the ultraviolet to the sub-millimetre wavelengths (MAJIS, UVS, SWI). A geophysical package consists of a laser altimeter (GALA) and a radar sounder (RIME) for exploring the surface and subsurface of the moons, and a radio science experiment (3GM) to probe the atmospheres of Jupiter and its satellites and to perform measurements of the gravity fields. An in situ package comprises a particle package (PEP) including plasma and energetic particle sensors, neutral gas mass spectrometer, and two ENA imagers, a magnetometer (J-MAG) and a radio and plasma wave instrument (RPWI), including electric fields sensors and a Langmuir probe. An experiment (PRIDE) using ground-based Very-Long-Baseline Interferometry (VLBI) will provide precise determination of the moons ephemerides. The launch of the JUICE spacecraft is foreseen in June 2022. After the Jupiter orbit insertion in January 2030, the spacecraft will perform a 2.5 years tour in the Jovian system investigating the atmosphere and magnetosphere of the giant. Gravity assists at Callisto will shape the trajectory to perform two targeted Europa flybys aiming at raising the orbit inclination up to 30 degrees. More than 10 Callisto flybys will enable unique remote observations of the moon and in situ measurements in its vicinity. The mission will culminate in a dedicated 8 months orbital tour around Ganymede. The presentation will give a status of the JUICE mission in the end of the definition phase, its science scenario, observation strategy, and the payload.

  17. The Helicity Injected Torus (HIT) Program

    NASA Astrophysics Data System (ADS)

    Jarboe, T. R.; Gu, P.; Hamp, W. T.; Izzo, V. A.; Nelson, B. A.; O'Neill, R. G.; Raman, R.; Redd, A. J.; Sieck, P. E.; Smith, R. J.; Nagata, M.; Uyama, T.; Jain, K. K.

    2002-11-01

    The Helicity Injected Torus (HIT) program develops current drive techniques for low-aspect-ratio toroidal plasmas. The present HIT--II spherical tokamak device is capable of driving current using both Coaxial Helicity Injection (CHI) and Ohmic transformer drive. The HIT--II device is modestly sized (major radius of 0.3 m, minor radius of 0.2 m, with on-axis toroidal fields of up to 0.5 T), but has demonstrated toroidal plasma currents of up to 200 kA, using either CHI or Ohmic drive. Recent experiments have included exploration of current drive mixing scenarios, in addition to detailed studies of the physics of low-aspect-ratio Ohmic and CHI-driven plasmas. An overview of ongoing research on HIT--II plasmas will be presented, especially diagnostic data from multi-chord FIR interferometry, multi-point Thomson scattering and sets of triple Langmuir probes. In the near future, the HIT--II device will be replaced by the Helicity Injected Torus with Steady Inductive helicity injection (HIT--SI), a device capable of generating and sustaining a high-beta low-aspect-ratio toroidal plasma. The final design of the HIT--SI device, and construction milestones, will be presented.

  18. Research Program of National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Peng, Y.-K. M.; Synakowski, E. J.

    2000-10-01

    The mission of NSTX research program is to prove the fusion plasma physics principles of the innovative spherical torus (ST) concept. The research objective for the near term (2000-2004) is to make preliminary determination of the attractiveness of the ST, by assessing high-beta stability, confinement, self-consistent high-bootstrap operation, and acceptable divertor heat flux, for pulse lengths much greater than the energy confinement times. The objectives for the longer term (2005-2009) are to assess the attractiveness of extrapolable, long-pulse operation of the spherical torus for pulse lengths much greater than the current penetration times; and the potential of spherical torus as a basis for burning plasma studies and/or fusion-nuclear component testing. The scientific milestones and the NSTX capabilities required to address the near term objective have been identified through input and discussions at the annual NSTX Research Forums, and improved based on comments of the NSTX Program Advisory Committee. The major elements of the NSTX research program will be presented.

  19. Jovian probe wake flowfield. [For the Galileo spacecraft

    NASA Technical Reports Server (NTRS)

    Engel, C. D.

    1979-01-01

    The base heating problem in the Jovian probe was examined. The entire wake flowfield is defined to calculate the radiative heating to the base region of the Jovian probe. Engineering tools for calculating the probe's wake flowfield are developed. The near and far viscous and inviscid flowfields for three entry conditions are calculated. The flowfields include pressure, temperature, and species concentration for radiation analysis. A mathematical model used in the calculations is described. The results obtained indicate that temperatures in the Jovian probe range from 4,000 to 10,00 K and pressures range from 10 to 1,000 times the free stream value.

  20. Jovian narrow-band as generator of the Jovian millisecond radio bursts

    NASA Astrophysics Data System (ADS)

    Boudjada, M. Y.; Galopeau, P. H. M.; Rucker, H. O.; Lecacheux, A.

    2000-11-01

    We report on the narrow-band emissions observed in the dynamic spectra of the Jovian decametric radio emissions. Such narrow-band emissions are infrequent phenomena and are related to the Jovian millisecond radio bursts (S-bursts). From the Riihimaa catalogue (Riihimaa 1991) we select narrow-band events observed in Oulu (Finland) with an acousto-optic spectrograph (AOS) with a high time resolution of about 7 ms. The AOS receiver gives the possibility to study the relationship between the S-bursts and the Jovian narrow-band emissions. For this we use the Riihimaa classification which shows sketches of millisecond radio bursts as they appear on the dynamic spectra and allows to distinguish one S-burst from another. The analysis of the temporal evolution of the Jovian narrow-band leads to a new interpretation of the Riihimaa structures. We show that each individual structure could be decomposed in one, two or three components and related to the narrow-band. It appears that the temporal evolution of the narrow-band involves the presence of fine structures, i.e. S-bursts, with a short time duration of about few tens of milliseconds. The individual S-burst duration and the short time scale of the gap in the narrow-band account for a mechanism totally intrinsic to the radio source. Taking into consideration our new results, we show that two models, the feedback model (Calvert 1982) and filamentary model (Louarn 1997) could explain part but not the global observed features of the narrow-band. According to the previous models the drift rate of the individual S-bursts seems to associate the combined effect of the source width with the refractive index or the geometry of the source relatively to the observer.

  1. The Orbits of the Regular Jovian Satellites

    NASA Astrophysics Data System (ADS)

    Jacobson, R.

    2014-04-01

    At the conclusion of the Galileo Mission we produced ephemerides for the Galilean and four inner Jovian satellites, Amalthea, Thebe, Adrastea, and Metis [1]. The satellite orbits were determined by fitting a data set that included Earthbased astrometry through 2001 and data acquired by the Pioneer, Voyager, Ulysses, Cassini, and Galileo spacecraft. The spacecraft tracking data provided additional information on the Jovian system gravity parameters. In preparation for the Juno mission currently enroute to Jupiter, we have been developing new ephemerides from updated satellite orbits. As before, the orbits are determined through a comprehensive data fit which also redetermines the gravity parameters and spacecraft trajectories to be consistent with the revised satellite orbits. Our standard model for the orbits, both satellite and spacecraft, is a numerical integration of their equations of motion. We include the gravitational effects of the point mass mutual interactions of Jupiter, the Galilean satellites, and Amalthea (Thebe, Adrastea, and Metis are assumed to be massless), the effects of an oblate Jupiter, and perturbations from the Sun and planets. For our new orbits we also take into account the effects of tides raised on Jupiter by the satellites. Lainey et al. [4] have pointed out the importance of the tidal accelerations. The spacecraft are also affected by nongravitational forces, e.g., solar radiation pressure, trajectory correction maneuvers. These forces are discussed by several authors [2, 3, 5]. Our current data set is an expansion of that used previously. We have extended the Galilean satellite Earthbased astrometry back to 1891 and forward to 2013 and the inner satellite astrometry back to 1892 and forward to 2002. We added the Galilean satellite mutual events from 2003 and 2009, the Galilean satellite eclipse timings from 1878 to 2013, and the Earthbased radar ranges to Ganymede and Callisto measured in 1992. We also augmented our spacecraft data set with imaging acquired by the New Horizons spacecraft when it flew through the Jovian system in February 2007. In this paper we present the results of our latest determination of the satellite orbits and associated gravity parameters. We compare the orbits and gravity parameters to those that we found previously and our tidal parameters to those of Lainey et al.. We comment on possible future modifications and enhancements before our ephemeris delivery to the Juno Project for orbital operations.

  2. Jovian Chromophore Characteristics from Multispectral HST Images

    NASA Technical Reports Server (NTRS)

    Strycker, Paul D.; Chanover, Nancy J.; Simon-Miller, Amy A.; Banfield, Don; Gierasch, Peter J.

    2011-01-01

    The chromophores responsible for coloring the jovian atmosphere are embedded within Jupiter's vertical aerosol structure. Sunlight propagates through this vertical distribution of aerosol particles, whose colors are defined by omega-bar (sub 0)(lambda), and we remotely observe the culmination of the radiative transfer as I/F(lambda). In this study, we employed a radiative transfer code to retrieve omega-bar (sub 0)(lambda) for particles in Jupiter's tropospheric haze at seven wavelengths in the near-UV and visible regimes. The data consisted of images of the 2008 passage of Oval BA to the south of the Great Red Spot obtained by the Wide Field Planetary Camera 2 on-board the Hubble Space Telescope. We present derived particle colors for locations that were selected from 14 weather regions, which spanned a large range of observed colors. All omega-bar (sub 0)(lambda) curves were absorbing in the blue, and omega-bar (sub 0)(lambda) increased monotonically to approximately unity as wavelength increased. We found accurate fits to all omega-bar (sub 0)(lambda) curves using an empirically derived functional form: omega-bar (sub 0)(lambda) = 1 A exp(-B lambda). The best-fit parameters for the mean omega-bar (sub 0)(lambda) curve were A = 25.4 and B = 0.0149 for lambda in units of nm. We performed a principal component analysis (PCA) on our omega-bar (sub 0)(lambda) results and found that one or two independent chromophores were sufficient to produce the variations in omega-bar (sub 0)(lambda). A PCA of I/F(lambda) for the same jovian locations resulted in principal components (PCs) with roughly the same variances as the omega-bar (sub 0)(lambda) PCA, but they did not result in a one-to-one mapping of PC amplitudes between the omega-bar (sub 0)(lambda) PCA and I/F(lambda) PCA. We suggest that statistical analyses performed on I/ F(lambda) image cubes have limited applicability to the characterization of chromophores in the jovian atmosphere due to the sensitivity of 1/ F(lambda) to horizontal variations in the vertical aerosol distribution.

  3. Large amplitude MHD waves upstream of the Jovian bow shock

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Smith, C. W.; Matthaeus, W. H.

    1983-01-01

    Observations of large amplitude magnetohydrodynamics (MHD) waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 mHz have a direction of minimum variance along the direction of the average magnetic field. The direction of minimum variance of these fluctuations lies at approximately 40 deg. to the magnetic field and is parallel to the radial direction. We argue that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the plasma rest frame. A linear instability analysis is presented which suggests an explanation for many of the observed features of the observations.

  4. X-ray production experiments on the RACE Compact Torus Accelerator

    Microsoft Academic Search

    J. H. Hammer; J. L. Eddleman; C. W. Hartman; H. S. McLean; A. W. Molvik; M. Gee

    1989-01-01

    The Purpose of the Compact Torus Accelerator (CTA) program at LLNL is to prove the principle of a unique accelerator concept based on magnetically confined compact torus (CT) plasma rings and to study applications. Successful achievement of these goals could lead to a high power-density driver for many applications including an intense x-ray source for nuclear weapons effects simulation and

  5. Ion heating during magnetic relaxation in the helicity injected torus-II experiment

    Microsoft Academic Search

    R. G. O'Neill; A. J. Redd; W. T. Hamp; R. J. Smith; T. R. Jarboe

    2005-01-01

    Ion doppler spectroscopy (IDS) is applied to the helicity injected torus (HIT-II) spherical torus to measure impurity ion temperature and flows. [A. J. Redd et al., Phys. Plasmas 9, 2006 (2002)] The IDS instrument employs a 16-channel photomultiplier and can track temperature and velocity continuously through a discharge. Data for the coaxial helicity injection (CHI), transformer, and combined current drive

  6. Energetic particles in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Trainor, J. H.; Mcdonald, F. B.; Teegarden, B. J.; Webber, W. R.; Roelof, E. C.

    1974-01-01

    A detailed account of the Pioneer 10 encounter with Jupiter is presented. Flux time histories of electrons and protons are given over a wide energy band. Proton and electron energy spectra are given at various Jovicentric distances. Proton spectra are shown to transform from a power law with indices in the 3-4.2 range to more nearly exponential forms in the inner regions. Extensive data are presented on the angular distributions of protons and electrons at various locations in the Jovicentric magnetosphere. In addition, a harmonic analysis of 1-2 MeV proton angular distributions was performed. Alpha/proton ratios are given as a function of Jovian radius and are compared to the earth and solar wind values.

  7. Magnetohydrodynamic Modeling of the Jovian Magnetosphere

    NASA Technical Reports Server (NTRS)

    Walker, Raymond

    2005-01-01

    Under this grant we have undertaken a series of magnetohydrodynamic (MHD) simulation and data analysis studies to help better understand the configuration and dynamics of Jupiter's magnetosphere. We approached our studies of Jupiter's magnetosphere in two ways. First we carried out a number of studies using our existing MHD code. We carried out simulation studies of Jupiter s magnetospheric boundaries and their dependence on solar wind parameters, we studied the current systems which give the Jovian magnetosphere its unique configuration and we modeled the dynamics of Jupiter s magnetosphere following a northward turning of the interplanetary magnetic field (IMF). Second we worked to develop a new simulation code for studies of outer planet magnetospheres.

  8. Acceleration of compact toruses and fusion applications

    SciTech Connect

    Hartman, C.W.; Eddleman, J.L.; Hammer, J.H.; Logan, B.G.; McLean, H.S.; Molvik, A.W.

    1990-10-11

    The Compact Torus (Spheromak-type) is a near ideal plasma confinement configuration for acceleration. The fields are mostly generated by internal plasma currents, plasma confinement is toroidal, and the compact torus exhibits resiliency and stability in virtue of the ``rugged`` helicity invariant. Based on these considerations we are developing a coaxial rail-gun type Compact Torus Accelerator (CTA). In the CTA, the CT ring is formed between coaxial electrodes using a magnetized Marshall gun, it is quasistatically ``precompressed`` in a conical electrode section for inductive energy storage, it is accelerated in a straight-coaxial electrode section as in a conventional rail-gun, and it is focused to small size and high energy and power density in a final ``focus`` cone section. The dynamics of slow precompression and acceleration have been demonstrated experimentally in the RACE device with results in good agreement with 2-D MHD code calculations. CT plasma rings with 100 {micro}gms mass have been accelerated to 40 Kj kinetic energy at 20% efficiency with final velocity = 1 X 10{sup 8} cm/s (= 5 KeV/H{sup +}). Preliminary focus tests exhibi dynamics of radius compression, deceleration, and bouncing. Compression ratios of 2-3 have been achieved. A scaled-up 10-100 MJ CTA is predicted to achieve a focus radius of several cm to deliver = 30 MJ ring kinetic energy in 5-10 nsec. This is sufficient energy, power, and power density to enable the CTA to act as a high efficiency, low cost ICF driver. Alternatively, the focused CT can form the basis for an magnetically insulated, inertial confinement fusion (MICF) system. Preliminary calculations of these fusion systems will be discussed.

  9. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 98, NO. A12, PAGES 21,163-21,176, DECEMBER 1, 1993 Bernstein Waves in the Io Plasma Torus' A Novel Kind of Electron

    E-print Network

    Demoulin, Pascal

    -product, we also deducethe magneticfield strengthwith a few percent error. 1. INTRODUCTION During the Jovian bandedemissions have been observedin the magnetospheresof Earth [e.g., Shaw and Gurnett, 1975;Christiansenet al magnetosphereof the Earth can be interpreted as quasi- thermal fluctuations in Bernstein waves. We shall calculate

  10. National Spherical Torus Experiment (NSTX) Program Overview*

    NASA Astrophysics Data System (ADS)

    Peng, Y.-K. M.; Synakowski, E. J.

    2001-10-01

    The mission of the NSTX research program is to prove the scientific principles of high temperature spherical torus (ST) plasmas. The near term goal is to determine the attractiveness of the noninductive-assisted plasmas for durations much larger than the energy confinement times. The NSTX National Team recently produced the initial plasma regimes (characterized by low collisionality, adequate Greenwald densities, toroidal betas above 0.2, H-mode and internal transport barrier behaviors under efficient NBI or HHFW heating, supra-Alfven fast ions, plasma Mach numbers near 0.5, and Alfven Mach numbers near 0.3 in over-dense plasmas) uniquely suited for the goal and mission. Coaxial Helicity Injection also reached a plasma current regime suitable for studying magnetic reconnections to close the flux surfaces. The next research goal is to determine the attractiveness of noninductive-sustained plasmas, which will require a long-pulse upgrade of NSTX. This new database will clarify the ST potential for testing pulsed high-gain burning plasma physics and producing sustained moderate-gain burning plasmas to develop fusion technologies. *Supported by DOE DE-AC02-76-CH03073 and DE-AC05-96OR22464.

  11. The large-scale energetic ion layer in the high latitude Jovian magnetosphere as revealed by Ulysses/HI-SCALE cross-field intensity-gradient measurements

    E-print Network

    Anagnostopoulos, G C; Marhavilas, P K; Sarris, E T

    2012-01-01

    Ulysses investigated the high latitude Jovian magnetosphere for a second time after Pioneer 11 mission and gave us the opportunity to search the structure and the dynamics of this giant magnetosphere above the magnetodisc. Kivelson(1976) and Kennel & Coroniti(1979) reported that Pioneer 11 observed energetic particle intensities at high latitudes at the same level with those measured in the plasma sheet and inferred that they were not consistent with the magnetodisc model. Ulysses observations supported the idea about a large-scale layer of energetic ions and electrons in the outer high latitude Jovian magnetosphere (Cowley et al.1996; Anagnostopoulos et al. 2001). This study perform a number of further tests for the existence of the large scale layer of energetic ions in the outer high latitude Jovian magnetosphere by studying appropriate cross-B field anisotropies in order to monitor the ion northward/southward intensity gradients. In particular, we examined Ulysses/HI-SCALE observations of energetic io...

  12. Cassini ENA Observations of an Asymmetric Europa Torus with Indications of Magnetospheric Dynamics

    NASA Astrophysics Data System (ADS)

    Brandt, Pontus; Westlake, Joseph; Mauk, Barry; Mitchell, Donald

    2014-05-01

    From about December 2000 to January 2001 the Ion Neutral Camera (INCA) on board the Cassini spacecraft imaged Jupiter in Energetic Neutral Atoms (ENA) that are created when singly charged ions charge exchange with neutral gas atoms or molecules. The INCA observations were obtained from a distance of about 137-250 Jovian planetary radii (RJ) over an energy range from about 10 to 300 keV. These observations have been demonstrated to be consistent with a neutral gas torus encircling Jupiter at Europa's orbit (Mauk et al., 2004). Here, we present a new, detailed analysis of the ENA images implying an asymmetric Europa neutral gas torus with indications of magnetospheric dynamics. The analysis uses images with a minimum integration time and background. A forward model using a parametric energetic ion model and a neutral gas model simulates ENA images through the instrument response function of INCA in order to determine the spatial distribution of the neutral gas.

  13. Next Step Spherical Torus Design Studies

    SciTech Connect

    C. Neumeyer; P. Heitzenroeder; C. Kessel; M. Ono; M. Peng; J. Schmidt; R. Woolley; I. Zatz

    2002-11-08

    Studies are underway to identify and characterize a design point for a Next Step Spherical Torus (NSST) experiment. This would be a ''Proof of Performance'' device which would follow and build upon the successes of the National Spherical Torus Experiment (NSTX) a ''Proof of Principle'' device which has operated at PPPL since 1999. With the Decontamination and Decommissioning (D&D) of the Tokamak Fusion Test Reactor (TFTR) nearly completed, the TFTR test cell and facility will soon be available for a device such as NSST. By utilizing the TFTR test cell, NSST can be constructed for a relatively low cost on a short time scale. In addition, while furthering spherical torus (ST) research, this device could achieve modest fusion power gain for short-pulse lengths, a significant step toward future large burning plasma devices now under discussion in the fusion community. The selected design point is Q=2 at HH=1.4, P subscript ''fusion''=60 MW, 5 second pulse, with R subscript ''0''=1.5 m, A=1.6, I subscript ''p''=10vMA, B subscript ''t''=2.6 T, CS flux=16 weber. Most of the research would be conducted in D-D, with a limited D-T campaign during the last years of the program.

  14. Recent progress on spherical torus research

    NASA Astrophysics Data System (ADS)

    Ono, Masayuki; Kaita, Robert

    2015-04-01

    The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ˜ 1.5, well below the normal tokamak operating range of A ? 2.5. As the aspect ratio is reduced, the ideal tokamak beta ? (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as ? ˜ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation ?, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of an attractive fusion energy power source. Since the start of the two mega-ampere class ST facilities in 2000, the National Spherical Torus Experiment in the United States and Mega Ampere Spherical Tokamak in UK, active ST research has been conducted worldwide. More than 16 ST research facilities operating during this period have achieved remarkable advances in all fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.

  15. Recent Progress on Spherical Torus Research

    SciTech Connect

    Ono, Masayuki [PPPL; Kaita, Robert [PPPL

    2014-01-01

    The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ? 2.5. As the aspect ratio is reduced, the ideal tokamak beta ? (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as ? ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation ?, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.

  16. Superfine Structure of Jovian Millisecond Radio Bursts

    NASA Astrophysics Data System (ADS)

    Rucker, H. O.; Litvinenko, G.; Taubenschuss, U.; Leitner, M.; Lecacheux, A.; Konovalenko, A.

    2004-05-01

    Jupiter decameter (DAM) radio emission mainly consists of wide-band radio storms with time scales in seconds (L-bursts) and milliseconds (S-bursts), the latter comprising a series of short pulses with duration of a few to tens of milliseconds, and strongly controlled by the satellite Io. First in-depth analysis of the subpulse structure was made by Carr and Reyes (1999) with the discovery of successive deep envelope modulations, with time resolution better than 30 microseconds, and during these subpulse periods the discovery of phase coherence. Recent observations by means of the newly developed waveform receiver (at present unsurpassed in spectral resolution) and connected to the decameter world-largest radio telescope UTR-2 (Kharkov) yielded waveform measurements of Jovian S-bursts which have been analyzed by the wavelet analysis method. Main outcome of the present investigation is the detection of clear signatures of microsecond modulations, providing evidence of a superfine burst structure with the following parameters: a) instantaneous frequency band of one separated microsecond pulse of 100 to 300 kHz, b) time duration of one separated micropulse of 6 to 15 microseconds, and c) time interval between closest subsequent microsecond pulses of 5 to 25 microseconds. The apparent frequency drift of a millisecond burst evidently results from sequentially decreasing frequencies of subsequent subpulses, each representing an island of phase coherent gyrating electron bunches.

  17. Rotation lightcurves of small jovian Trojan asteroids

    NASA Astrophysics Data System (ADS)

    French, Linda M.; Stephens, Robert D.; Coley, Daniel; Wasserman, Lawrence H.; Sieben, Jennifer

    2015-07-01

    Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We present new lightcurve information for 19 Trojans ? 30 km in diameter, more than doubling the number of objects in this size range for which some rotation information is known. The minimum densities for objects with complete lightcurves are estimated and are found to be comparable to those measured for cometary nuclei. A significant fraction (?40%) of this observed small Trojan population rotates slowly (P > 24 h), with measured periods as long as 375 h (Warner, B.D., Stephens, R.D. [2011]. Minor Planet Bull. 38, 110-111). The excess of slow rotators may be due to the YORP effect. Results of the Kolmogorov-Smirnov test suggest that the distribution of Trojan rotation rates is dissimilar to those of Main Belt Asteroids of the same size. Concerted observations of a large number of Trojans could establish the spin barrier (Warner, B.D., Harris, A.W., Pravec, P. [2009]. Icarus 202, 134-146), making it possible to estimate densities for objects near the critical period.

  18. Neutral cloud and heavy ion inner torus at Saturn

    Microsoft Academic Search

    R. E. Johnson; M. K. Pospieszalska; E. C. Jr. Sittler; A. F. Cheng; L. J. Lanzerotti

    1989-01-01

    Voyager plasma data are used in conjunction with laboratory data on water molecule sputter-yields and energy distributions to calculate the morphology of the Saturn neutral water molecule and dissociated water molecule-product torus coexisting with the E-ring and icy satellites of this planet. Plasma production rates determined for this cloud exhibit a structure with distance from Saturn as well as from

  19. The global morphology of the Europa neutral torus from Cassini Energetic Neutral Atom (ENA) observations and implications for JUICE

    NASA Astrophysics Data System (ADS)

    Brandt, P. C.; Mauk, B.; Mitchell, D. G.; Paranicas, C.; Barabash, S. V.

    2013-12-01

    From about December 2000 to January 2001 the Ion Neutral Camera (INCA) on board the Cassini spacecraft imaged Jupiter in Energetic Neutral Atoms (ENA) that are created when singly charged ions charge exchange with neutral gas atoms or molecules. The INCA observations were obtained from a distance of about 137-250 Jovian planetary radii (RJ) over an energy range from about 10 to 300 keV. We present underlying neutral torus gas morphologies by simulating INCA images using an empirical ion distribution model and a range of theoretical gas model distributions. Just like Mauk et al. (2003), who used a different analysis technique, we find that the INCA images are consistent with a neutral torus at the orbital distance of Europa (9.5 RJ). However, within the limitations of instrument resolution, we present also possible solutions of a longitudinally asymmetric torus distribution and its implication for neutral gas release and loss rates from Europa. The Jovian Energetic Neutral and Ions (JENI) camera is the second generation ENA camera based on INCA and was selected for the science payload of the Jupiter Icy Moon Explorer (JUICE) mission, planned for launch around 2022 and orbit insertion around Jupiter in 2030. Using the same forward simulation technique as above, we use the INCA observations to demonstrate what we expect the JENI camera to observe in orbit around Jupiter and Ganymede.

  20. Torus Workshop 2012

    NASA Astrophysics Data System (ADS)

    Mason, R.; Alonso-Herrero, A.; Packham, C.

    2012-12-01

    The nature and origin of the dusty material at the heart of active galaxies - whether it is inflowing, outflowing, its relation to star formation, etc. - has profound implications for our understanding of the evolution and lifecycle of AGN. A sound understanding of local AGN will also allow us to model them with confidence and apply our models to forthcoming observations of objects in the distant Universe. The last few years have seen numerous developments in the field: exquisitely sensitive Spitzer spectra have revealed the infrared properties of large numbers of AGN; mid-infrared interferometry is an increasingly mature technique; and models of increasing sophistication have been developed to explore the observations, to name just a few examples. The Torus 2012 workshop was held at the University of Texas, San Antonio in December 2012. Specialists in these and related areas gathered to share knowledge, debate ideas, and come to the best possible understanding of the dusty structures in AGN.

  1. The Incredible Shrinking Torus

    E-print Network

    W. Fischler; E. Halyo; A. Rajaraman; L. Susskind

    1997-03-13

    Using M(atrix) Theory, the dualities of toroidally compactified M-theory can be formulated as properties of super Yang Mills theories in various dimensions. We consider the cases of compactification on one, two, three, four and five dimensional tori. The dualities required by string theory lead to conjectures of remarkable symmetries and relations between field theories as well as extremely unusual dynamical properties. By studying the theories in the limit of vanishingly small tori, a wealth of information is obtained about strongly coupled fixed points of super Yang-Mills theories in various dimensions. Perhaps the most striking behavior, as noted by Rozali in this context, is the emergence of an additional dimension of space in the case of a four torus.

  2. Characteristics of Energy Transport of Li-conditioned and non-Li-conditioned Plasmas in the National Spherical Torus Experiment (NSTX)

    SciTech Connect

    Ding, S.; Kaye, S. M.; Bell, R. E.; Kaita, R.; Kugel, H.; LeBlanc, B. P.; Paul, S.; Wan, B.

    2009-10-21

    The transport properties of NSTX plasmas obtained during the 2008 experimental cam- paign have been studied and are reported here. Transport trends and dependences have been isolated, and it is found that both electron and ion energy transport coefficients have strong dependences on local values of n?T, which in turn is strongly dependent on local current density profile. Without identifying this dependence, it is difficult to identify others, such as the dependence of transport coefficients on Bp (or q), Ip and Pheat. In addition, a comparison between discharges with and without Lithium wall conditioning has been made. While the trends in the two sets of data are similar, the thermal transport loss, especially in the electron channel, is found to strongly depend on the amount of Lithium deposited, decreasing by up to 50% of its no-Lithium value.

  3. The Influence of Magnetospheric Plasma on Magnetic Sounding of Europa's Interior Oceans

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; Rymer, A. M.; Kasper, J. C.; McNutt, R. L.; Stevens, M. L.; Smith, H. T.; Parker, C.; Case, A. W.; Ho, G. C.; Mitchell, D. G.

    2014-02-01

    We discuss measurements of the Jovian and Europan plasma environments necessary for magnetic sounding of Europa's subsurface oceans. We introduce a suite of Faraday cup instrumentation that can provide these high quality plasma measurements.

  4. Thermoelectric Rotating Torus for Fusion A. B. Hassam and Yi-Min Huang

    E-print Network

    Hassam, Adil

    Thermoelectric Rotating Torus for Fusion A. B. Hassam and Yi-Min Huang Institute for Plasma power maintains the rotation and also heats the plasma. The thermoelectric effect from the resultingRevLett.91.195002 PACS numbers: 52.58.­c, 52.30.­q, 52.55.­s In magnetized plasma, thermoelectric currents

  5. Cross-field potential hill arisen eccentrically in toroidal electron cyclotron resonance plasmas in the Low Aspect ratio Torus Experiment device to regulate electron and ion flows from source to boundary

    NASA Astrophysics Data System (ADS)

    Kuroda, Kengoh; Wada, Manato; Uchida, Masaki; Tanaka, Hitoshi; Maekawa, Takashi

    2015-07-01

    We have investigated the electron and ion flows in toroidal electron cyclotron resonance (ECR) plasmas maintained by a 2.45 GHz microwave power around 1 kW under a simple toroidal field in the low aspect ratio torus experiment (LATE) device. We have found that a vertically uniform ridge of electron pressure that also constitutes the source belt of electron impact ionization is formed along just lower field side of the ECR layer and a cross-field potential hill ({{V}S}\\cong 30?V while {{T}e}\\cong 10?eV), eccentrically shifted toward the corner formed by the top panel and the ECR layer, arises. Combination of the hill-driven E× B drift and the vertical drift due to the field gradient and curvature, being referred to as vacuum toroidal field (VTF) drift, realizes steady flows of electrons and ions from the source to the boundary. In particular, the ions, of which VTF drift velocity is much slower than the electron VTF drift velocity near the source belt, are carried by the E× B drift around the hill to the vicinity of the top panel, where the ion VTF drift is enhanced on the steep down slope of potential toward the top panel. On the other hand the electron temperature strongly decreases in this area. Thus the carrier of VTF drift current is replaced from the electrons to the ions before the top panel, enabling the current circulation through the top and bottom panels and the vessel (electrons mainly to the bottom and ions mainly to the top) that keeps the charge neutrality very high. A few percent of electrons from the source turn around the hill by 360 degree and reentry the source belt from the high field side as seed electrons for the impact ionization, keeping the discharge stable.

  6. Next-Step Spherical Torus Experiment and Spherical Torus Strategy in the Fusion Energy Development Path

    SciTech Connect

    M. Ono; M. Peng; C. Kessel; C. Neumeyer; J. Schmidt; J. Chrzanowski; D. Darrow; L. Grisham; P. Heitzenroeder; T. Jarboe; C. Jun; S. Kaye; J. Menard; R. Raman; T. Stevenson; M. Viola; J. Wilson; R. Woolley; I. Zatz

    2003-10-27

    A spherical torus (ST) fusion energy development path which is complementary to proposed tokamak burning plasma experiments such as ITER is described. The ST strategy focuses on a compact Component Test Facility (CTF) and higher performance advanced regimes leading to more attractive DEMO and Power Plant scale reactors. To provide the physics basis for the CTF an intermediate step needs to be taken which we refer to as the ''Next Step Spherical Torus'' (NSST) device and examine in some detail herein. NSST is a ''performance extension'' (PE) stage ST with the plasma current of 5-10 MA, R = 1.5 m, and Beta(sub)T less than or equal to 2.7 T with flexible physics capability. The mission of NSST is to: (1) provide a sufficient physics basis for the design of CTF, (2) explore advanced operating scenarios with high bootstrap current fraction/high performance regimes, which can then be utilized by CTF, DEMO, and Power Plants, and (3) contribute to the general plasma/fusion science of high beta toroidal plasmas. The NSST facility is designed to utilize the Tokamak Fusion Test Reactor (or similar) site to minimize the cost and time required for the design and construction.

  7. Space Propulsion via Spherical Torus Fusion Reactor

    SciTech Connect

    Williams, Craig H.; Juhasz, Albert J.; Borowski, Stanley K.; Dudzinski, Leonard A. [NASA Glenn Research Center (United States)

    2003-01-15

    A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 204 days, with an initial mass in low Earth orbit of 1630 mt. Engineering conceptual design, analysis, and assessment were performed on all major systems including nuclear fusion reactor, magnetic nozzle, power conversion, fast wave plasma heating, fuel pellet injector, startup/re-start fission reactor and battery, and other systems. Detailed fusion reactor design included analysis of plasma characteristics, power balance and utilization, first wall, toroidal field coils, heat transfer, and neutron/X-ray radiation.

  8. On the detectability of Jovian oscillations with infrared heterodyne measurements

    NASA Astrophysics Data System (ADS)

    Mosser, Benoit; Gautier, Daniel; Kostiuk, Theodor

    1992-03-01

    A method is proposed for detecting Jovian global oscillations using IR heterodyne measurements in the lower stratosphere of the planet. Measurements of the S(0) and S(1) lines over a period of a few nights permitted the detection of modes with periods of 5 to 20 min and of Doppler shifts corresponding to velocities as low as 1 m/sec (which is less than the value reported by Schmider and Mosser, 1990 from observations of the Jovian troposphere in the visible range. Possible limitations of the method are pointed out.

  9. On the detectability of Jovian oscillations with infrared heterodyne measurements

    NASA Technical Reports Server (NTRS)

    Mosser, Benoit; Gautier, Daniel; Kostiuk, Theodor

    1992-01-01

    A method is proposed for detecting Jovian global oscillations using IR heterodyne measurements in the lower stratosphere of the planet. Measurements of the S(0) and S(1) lines over a period of a few nights permitted the detection of modes with periods of 5 to 20 min and of Doppler shifts corresponding to velocities as low as 1 m/sec (which is less than the value reported by Schmider and Mosser, 1990 from observations of the Jovian troposphere in the visible range. Possible limitations of the method are pointed out.

  10. On the proposed triggering of Jovian radio emissions

    NASA Astrophysics Data System (ADS)

    Desch, M. D.; Kaiser, M. L.

    1985-09-01

    Calvert (1985) has proposed that solar type III radio bursts can trigger the onset of certain Jovian hectometer wavelength emissions. The authors show, using the data obtained by the Voyager Planetary Radio Astronomy experiment, that this triggering hypothesis is not supported statistically. Furthermore, the authors question the causality of this proposed triggering because much of the Jovian hectometer emission is due to a quasi-continuous radio source rotating, in lighthouse fashion, with Jupiter. Thus, an observed "onset" of emission is simply a function of the observer's position in local time around Jupiter.

  11. Similarities and Differences of Transport in the Terrestrial and Jovian Environments

    NASA Astrophysics Data System (ADS)

    Kivelson, M. G.

    2001-12-01

    Jupiter's magnetosphere differs from the terrestrial magnetosphere in ways that critically modify the transport of plasma through the system. Of great consequence is the fact that Jupiter's moon Io provides a source of heavy ion plasma deep within the magnetosphere. The rapid rotation of the planet subjects the plasma to large rotational accelerations. Interchange instability is of little consequence at Earth but is identified at Jupiter and may be of critical importance in transporting Jovian plasma. Conservation of angular momentum causes the plasma to slow its angular speed with outward motion and this drives currents that couple the equatorial magnetosphere to the auroral zone, producing an aurora with very different sources from those familiar at Earth. The gargantuan scale of the magnetosphere affects the conservation of adiabatic invariants, with time scales of planetary rotation short or of order of the bounce time of thermal plasma. This feature of the magnetosphere results in strong local time-dependent structure. We will discuss these and other aspects of the comparison of the two magnetospheres.

  12. Why a Windy Torus?

    E-print Network

    Gallagher, S C; Everett, J E; Keating, S; Deo, R P

    2013-01-01

    Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is even more important, as high energy photons from the central engine can now push on dust grains. This physics underlies the dusty-wind model for the putative obscuring torus. Specifically, the dusty wind in our model is first launched from the outer accretion disk as a magneto-centrifugal wind and then accelerated and shaped by radiation pressure from the central continuum. Such a wind can plausibly account for both the necessary obscuring medium to explain the ratio of broad-to-narrow-line objects and the mid-infrared emission commonly seen in quasar spectral energy distributions. A convincing demonstration that large-scale, organized magnetic fields are pr...

  13. Why a Windy Torus?

    NASA Astrophysics Data System (ADS)

    Gallagher, S. C.; Abado, M. M.; Everett, J. E.; Keating, S.; Deo, R. P.

    2012-12-01

    Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is even more important, as high energy photons from the central engine can now push on dust grains. This physics underlies the dusty-wind model for the putative obscuring torus. Specifically, the dusty wind in our model is first launched from the outer accretion disk as a magneto-centrifugal wind and then accelerated and shaped by radiation pressure from the central continuum. Such a wind can plausibly account for both the necessary obscuring medium to explain the ratio of broad-to-narrow-line objects and the mid-infrared emission commonly seen in quasar spectral energy distributions. A convincing demonstration that large-scale, organized magnetic fields are present in radio-quiet active galactic nuclei is now required to bolster the case for this paradigm.

  14. The Ultraviolet Spectrum of the Jovian Dayglow

    NASA Technical Reports Server (NTRS)

    Liu, Weihong; Dalgarno, A.

    1995-01-01

    The ultraviolet spectra of molecular hydrogen H2 and HD due to solar fluorescence and photoelectron excitation are calculated and compared with the Jovian equatorial dayglow spectrum measured at 3 A resolution at solar maximum. The dayglow emission is accounted for in both brightness and spectral shape by the solar fluorescence and photoelectron excitation and requires no additional energy source. The emission is characterized by an atmospheric temperature of 530 K and an H2 column density of 10(exp 20) cm(exp -2). The dayglow spectrum contains a cascade contribution to the Lyman band emission from high-lying E and F states. Its relative weakness at short wavelengths is due to both self-absorption by H2 and absorption by CH4. Strong wavelength coincidences of solar emission lines and absorption lines of H2 and HD produce unique line spectra which can be identified in the dayglow spectrum. The strongest fluorescence is due to absorption of the solar Lyman-beta line at 1025.72 A by the P(1) line of the (6, 0) Lyman band of H2 at 1025.93 A. The fluorescence lines due to absorption of the solar O 6 line at 1031.91 A by vibrationally excited H2 via the Q(3) line of the (1, 1) Werner band at 1031.86 A are identified. The fluorescence lines provide a sensitive measure of the atmospheric temperature. There occurs an exact coincidence of the solar O 6 line at 1031.91 A and the R(0) line of the (6, 0) Lyman band of HD at 1031-91 A, but HD on Jupiter is difficult to detect due to the dominance of the H2 emission where the HD emission is particularly strong. Higher spectral resolution and higher sensitivity may make possible such a detection. The high resolution (0.3 A) spectra of H2 and HD are presented to stimulate search for the HD on Jupiter with the Hubble Space Telescope.

  15. A global magnetohydrodynamic simulation of the Jovian magnetosphere

    Microsoft Academic Search

    Tatsuki Ogino; Raymond J. Walker; Margaret G. Kivelson

    1998-01-01

    We have developed a three-dimensional global magnetohydrodynamic simulation of the interaction between the solar wind and a rapidly rotating magnetosphere and applied it to Jupiter. For fixed solar wind dynamic pressure the rotating model Jovian magnetosphere extends farther toward the Sun and has greater extent in the east-west direction than a model without rotation but is little different in the

  16. A Normal-Mode Approach to Jovian Atmospheric Dynamics

    Microsoft Academic Search

    Richard K. Achterberg; Andrew P. Ingersoll

    1989-01-01

    We propose a nonlinear, quasi-geostrophic, baroclinic model of Jovian atmospheric dynamics, in which vertical variations of velocity are represented by a truncated sum over a complete set of orthogonal functions obtained by a separation of variables of the linearized quasi-geostrophic potential vorticity quation. A set of equations for the time variation of the mode amplitudes in the nonlinear case is

  17. A normal-mode approach to Jovian atmospheric dynamic

    Microsoft Academic Search

    Richard K. Achterberg; Andrew P. Ingersoll

    1989-01-01

    A nonlinear, quasi-geostrophic, baroclinic model of Jovian atmospheric dynamics is proposed, in which vertical variations of velocity are represented by a truncated sum over a complete set of orthogonal functions obtained by a separation of variables of the linearized quasi-geostrophic potential vorticity equation. A set of equations for the time variation of the mode amplitudes in the nonlinear case is

  18. Corotation lag of the Jovian atmosphere, ionosphere, and magnetosphere

    Microsoft Academic Search

    T. S. Huang; T. W. Hill

    1989-01-01

    The authors modify the Jovian ionosphere-magnetosphere coupling model presented by Hill (1979) to include rotational slippage of the neutral atmosphere at ionospheric heights, relative to a frame of reference corotating rigidly with Jupiter. In the modified model, as altitude increases, the drift velocities of neutrals and ions relative to the corotating frame increase from zero at the bottom of the

  19. Exploration of spherical torus physics in the NSTX device

    NASA Astrophysics Data System (ADS)

    Ono, M.; Kaye, S. M.; Peng, Y.-K. M.; Barnes, G.; Blanchard, W.; Carter, M. D.; Chrzanowski, J.; Dudek, L.; Ewig, R.; Gates, D.; Hatcher, R. E.; Jarboe, T.; Jardin, S. C.; Johnson, D.; Kaita, R.; Kalish, M.; Kessel, C. E.; Kugel, H. W.; Maingi, R.; Majeski, R.; Manickam, J.; McCormack, B.; Menard, J.; Mueller, D.; Nelson, B. A.; Nelson, B. E.; Neumeyer, C.; Oliaro, G.; Paoletti, F.; Parsells, R.; Perry, E.; Pomphrey, N.; Ramakrishnan, S.; Raman, R.; Rewoldt, G.; Robinson, J.; Roquemore, A. L.; Ryan, P.; Sabbagh, S.; Swain, D.; Synakowski, E. J.; Viola, M.; Williams, M.; Wilson, J. R.; NSTX Team

    2000-03-01

    The National Spherical Torus Experiment (NSTX) is being built at Princeton Plasma Physics Laboratory to test the fusion physics principles for the spherical torus concept at the MA level. The NSTX nominal plasma parameters are R0 = 85 cm, a = 67 cm, R/a >= 1.26, Bt = 3 kG, Ip = 1 MA, q95 = 14, elongation ? <= 2.2, triangularity ? <= 0.5 and a plasma pulse length of up to 5 s. The plasma heating/current drive tools are high harmonic fast wave (6 MW, 5 s), neutral beam injection (5 MW, 80 keV, 5 s) and coaxial helicity injection. Theoretical calculations predict that NSTX should provide exciting possibilities for exploring a number of important new physics regimes, including very high plasma ?, naturally high plasma elongation, high bootstrap current fraction, absolute magnetic well and high pressure driven sheared flow. In addition, the NSTX programme plans to explore fully non-inductive plasma startup as well as a dispersive scrape-off layer for heat and particle flux handling.

  20. ULF waves in the Io torus: Ulysses observations

    NASA Technical Reports Server (NTRS)

    Lin, Naiguo; Kellogg, P. J.; Macdowell, R. J.; Mei, Y.; Cornilleau-Wehrlin, N.; Canu, P.; De Villedary, C.; Rezeau, L.; Balogh, L.; Forsyth, R. J.

    1993-01-01

    Throughout the Io torus, Ulysses has observed intense ultralow frequency (ULF) wave activity in both electric and magnetic components. Such ULF waves have been previously suggested as the source of ion precipitation leading to Jovian aurorae. The peaks of the wave spectra are closely related to the ion cyclotron frequencies, which is evidence of the waves being ion cyclotron waves (ICWs). Analysis of the dispersion relation using a multicomponent density model shows that at high latitudes (approximately 30 deg), peak frequencies of the waves fall into L mode branches of guided or unguided ICWs. Near the equator, in addition to the ICWs below f(sub cO(2+)), there are strong signals at approximately 10 Hz which require an unexpectedly large energetic ion temperature anistropy to be explained by the excitation of either convective or nonconvective ion cyclotron instabilities. Their generation mechanism remains open for the future study. Evaluation of the Poynting vector and the dispersion relation analysis suggest that the waves near the equator had a small wave angle relative to the magnetic field, while those observed at high latitudes were more oblique. The polarization of the waves below f(sub cH(+)) is more random than that of the whistler mode waves, but left-hand-polarized components of the waves can still be seen. The intensity of the ICWs both near the equator and at high latitudes are strong enough to meet the requirement for producing strong pitch angle scattering of energetic ions.

  1. Reactor assessments of advanced bumpy torus configurations

    Microsoft Academic Search

    N. A. Uckan; L. W. Owen; D. A. Spong; R. L. Miller; W. B. Ard; J. F. Pipkins; R. J. Schmitt

    1984-01-01

    Recently, several innovative approaches were introduced for enhancing the performance of the basic ELMO Bumpy Torus (EBT) concept and for improving its reactor potential. These include planar racetrack and square geometries, Andreoletti coil systems, and bumpy torus-stellarator hybrids (which include twisted racetrack and helical axis stellarator - snakey torus). Preliminary evaluations of reactor implications of each approach have been carried

  2. Reactor assessments of advanced bumpy torus configurations

    Microsoft Academic Search

    N. A. Uckan; L. W. Owen; D. A. Spong; R. L. Miller; W. B. Ard; J. F. Pipkins; R. J. Schmitt

    1983-01-01

    Recently, several configurational approaches and concept improvement schemes were introduced for enhancing the performance of the basic ELMO Bumpy Torus (EBT) concept and for improving its reactor potential. These configurations include planar racetrack and square geometries, Andreoletti coil systems, and bumpy torus-stellarator hybrids (which include twisted racetrack and helical axis stellarator-snakey torus). Preliminary evaluations of reactor implications of each of

  3. Generalized Fuzzy Torus and its Modular Properties

    NASA Astrophysics Data System (ADS)

    Schreivogl, Paul; Steinacker, Harold

    2013-10-01

    We consider a generalization of the basic fuzzy torus to a fuzzy torus with non-trivial modular parameter, based on a finite matrix algebra. We discuss the modular properties of this fuzzy torus, and compute the matrix Laplacian for a scalar field. In the semi-classical limit, the generalized fuzzy torus can be used to approximate a generic commutative torus represented by two generic vectors in the complex plane, with generic modular parameter ?. The effective classical geometry and the spectrum of the Laplacian are correctly reproduced in the limit. The spectrum of a matrix Dirac operator is also computed.

  4. Io as a source of the jovian dust streams

    PubMed

    Graps; Grun; Svedhem; Kruger; Horanyl; Heck; Lammers

    2000-05-01

    Streams of dust emerging from the direction of Jupiter were discovered in 1992 during the flyby of the Ulysses spacecraft, but their precise origin within the jovian system remained unclear. Further data collected by the Galileo spacecraft, which has been orbiting Jupiter since December 1995, identified the possible sources of dust as Jupiter's main ring, its gossamer ring, comet Shoemaker-Levy 9 (ref. 8) and Io. All but Jupiter's gossamer ring and Io have since been ruled out. Here we find that the dominant source of the jovian dust streams is Io, on the basis of periodicities in the dust impact signal. Io's volcanoes, rather than impact ejecta, are the dust sources. PMID:10811212

  5. Retrievals of jovian tropospheric phosphine from Cassini\\/CIRS

    Microsoft Academic Search

    P. G. J. Irwin; P. Parrish; T. Fouchet; S. B. Calcutt; F. W. Taylor; A. A. Simon-Miller; C. A. Nixon

    2004-01-01

    On December 30th, 2000, the Cassini–Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian System. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the jovian atmosphere, rings and satellites from 10–1400 cm?1 (1000–7 ?m) at a programmable spectral resolution of 0.5 to 15 cm?1. The improved spectral resolution of CIRS over

  6. Studies of thermal wave phenomena on the Jovian planets

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    1991-01-01

    Ground-based and Voyager observations of Jupiter provided evidence that the tropospheric temperature shows global-scale longitudinal variations which are often wavelike in character. The investigation is presented which is directed toward obtaining additional ground-based data in IR spectral bands whose contribution functions are optimized for specific atmospheric regions, in order to confirm the previous results, and to identify the nature and physical significance of wavelike longitudinal temperature fluctuations on the Jovian planets.

  7. Thermal shallow water models of geostrophic turbulence in Jovian atmospheres

    SciTech Connect

    Warneford, Emma S., E-mail: emma.warneford@maths.ox.ac.uk; Dellar, Paul J., E-mail: dellar@maths.ox.ac.uk [OCIAM, Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Oxford OX2 6GG (United Kingdom)

    2014-01-15

    Conventional shallow water theory successfully reproduces many key features of the Jovian atmosphere: a mixture of coherent vortices and stable, large-scale, zonal jets whose amplitude decreases with distance from the equator. However, both freely decaying and forced-dissipative simulations of the shallow water equations in Jovian parameter regimes invariably yield retrograde equatorial jets, while Jupiter itself has a strong prograde equatorial jet. Simulations by Scott and Polvani [“Equatorial superrotation in shallow atmospheres,” Geophys. Res. Lett. 35, L24202 (2008)] have produced prograde equatorial jets through the addition of a model for radiative relaxation in the shallow water height equation. However, their model does not conserve mass or momentum in the active layer, and produces mid-latitude jets much weaker than the equatorial jet. We present the thermal shallow water equations as an alternative model for Jovian atmospheres. These equations permit horizontal variations in the thermodynamic properties of the fluid within the active layer. We incorporate a radiative relaxation term in the separate temperature equation, leaving the mass and momentum conservation equations untouched. Simulations of this model in the Jovian regime yield a strong prograde equatorial jet, and larger amplitude mid-latitude jets than the Scott and Polvani model. For both models, the slope of the non-zonal energy spectra is consistent with the classic Kolmogorov scaling, and the slope of the zonal energy spectra is consistent with the much steeper spectrum observed for Jupiter. We also perform simulations of the thermal shallow water equations for Neptunian parameter values, with a radiative relaxation time scale calculated for the same 25 mbar pressure level we used for Jupiter. These Neptunian simulations reproduce the broad, retrograde equatorial jet and prograde mid-latitude jets seen in observations. The much longer radiative time scale for the colder planet Neptune explains the transition from a prograde to a retrograde equatorial jet, while the broader jets are due to the deformation radius being a larger fraction of the planetary radius.

  8. Coupling of pressure waves to clouds in the Jovian atmosphere

    NASA Astrophysics Data System (ADS)

    Gaulme, Patrick; Mosser, Benoît

    2004-12-01

    The receipt for a successful study of the Jovian interior structure is given by the association of seismology and precise visible photometry. In this framework, the micro-satellite project Jovis, presented to the French space agency (Mosser et al, these proceedings), is for Jupiter a copy of what the European space mission COROT is for the stars. The Jovian visible flux being dominated by the albedo map, an accurate analysis of the cloud response to a seismic wave is needed. Therefore, we have revisited the propagation of sound waves in the Jovian troposphere, in order to estimate how they affect the clouds layer. We suppose a vertical wave propagating in a plane parallel atmosphere including an ammonia ice cloud layer. First, considering Jupiter as a mirror, we establish the variations of the reflected solar flux due to the smooth distorsions. Second, introducing thermodynamics, we determine the phase transitions induced by the waves in the clouds. These phase changes are linked to the ice particles growth, and limited by kinetics. A Mie model associated to a simple radiation transfer model allows us to estimate the final albedo fluctuations of the cloud perturbed by a seismic wave. We are then able to quantify the albedo response to a pressure wave.

  9. WISE/NEOWISE OBSERVATIONS OF THE JOVIAN TROJANS: PRELIMINARY RESULTS

    SciTech Connect

    Grav, T. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Mainzer, A. K.; Bauer, J.; Masiero, J.; Eisenhardt, P. R. M.; Blauvelt, E.; DeBaun, E.; Elsbury, D.; Gautier, T. IV; Gomillion, S.; Hand, E.; Wilkins, A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Spahr, T. [Minor Planet Center, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); McMillan, R. S. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Walker, R. [Monterey Institute for Research in Astronomy, Marina, CA 93933 (United States); Cutri, R. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Wright, E., E-mail: tgrav@pha.jhu.edu [Division of Astronomy and Astrophysics, UCLA, Los Angles, CA 90095 (United States)

    2011-11-20

    We present the preliminary analysis of over 1739 known and 349 candidate Jovian Trojans observed by the NEOWISE component of the Wide-field Infrared Survey Explorer (WISE). With this survey the available diameters, albedos, and beaming parameters for the Jovian Trojans have been increased by more than an order of magnitude compared to previous surveys. We find that the Jovian Trojan population is very homogenous for sizes larger than {approx}10 km (close to the detection limit of WISE for these objects). The observed sample consists almost exclusively of low albedo objects, having a mean albedo value of 0.07 {+-} 0.03. The beaming parameter was also derived for a large fraction of the observed sample, and it is also very homogenous with an observed mean value of 0.88 {+-} 0.13. Preliminary debiasing of the survey shows that our observed sample is consistent with the leading cloud containing more objects than the trailing cloud. We estimate the fraction to be N(leading)/N(trailing) {approx} 1.4 {+-} 0.2, lower than the 1.6 {+-} 0.1 value derived by Szabo et al.

  10. Relationship between Jovian Hectometric Attenuation Lanes And Io Volcanic Activity

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Spencer, J. R.; Stansberry, J. A.

    2001-01-01

    Within the Galileo plasma wave instrument data a narrow (in frequency) attenuation band is seen in the hectometric (HOM) emission that varies in frequency with system III longitude. This attenuation lane is believed to be the result of near-grazing incidence or coherent scattering of radio emission near the outer edge of the Io torus, i.e., when the ray path is nearly tangent to an L shell containing the Io flux tube. Such a process should, therefore, be enhanced when the Io volcanic activity is increased and the Io flux tube has enhanced density. We have performed a systematic study of the existing Galileo radio emission data in an effort to determine the phenomenology and frequency of occurrence of the attenuation lanes and the association, if any, with published volcanic activity of Io. Our results indicate that the attenuation lanes are present almost all of the time but are enhanced on occasion. The best examples of attenuation lanes occur when Galileo is within approximately 65 R(sub J) of Jupiter and thus are probably more apparent because of the increased signal-to-noise ratio of the radio receivers. The lack of continuous monitoring of Io activity and the lack of known activity on the anti-Earthward side of Io are problematic and make detailed correlation with radio emission very difficult at this time. Nevertheless, if the data are displayed for periods when the spacecraft is within 65 R(sub J) (i.e., for each perijove pass), then the highest-contrast lanes occur on most passes when the Io volcanic activity is also high for that pass. These results support our current understanding of attenuation lane formation and suggest that future efforts can be made to better understand the interaction of HOM emission with the Io flux tube.

  11. The Jovian magnetotail and its current sheet

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.; Burlaga, L. F.; Ness, N. F.

    1980-01-01

    Analyses of Voyager magnetic field measurements have extended the understanding of the structural and temporal characteristics of Jupiter's magnetic tail. The magnitude of the magnetic field in the lobes of the tail is found to decrease with Jovicentric distance approximately as r to he-1.4, compared with the power law exponent of -1.7 found for the rate of decrease along the Pioneer 10 outbound trajectory. Voyager observations of magnetic field component variations with Jovicentric distance in the tail do not support the uniform radial plasma outflow model derived from Pioneer data. Voyager 2 has shown that the azimuthal current sheet which surrounds Jupiter in the inner and middle magnetosphere extends tailward (in the anti-Sun direction) to a distance of at least 100 R sub J. In the tail this current sheet consists of a plasma sheet and embedded neutral sheet. In the region of the tail where the sheet is observed, the variation of the magnetic field as a result of the sheet structure and its 10 hr periodic motion is the dominant variation seen.

  12. Torus Grid Graph Kneser Graph

    E-print Network

    ,3) Torus Grid Graph {1,4} {3,4} {1,2} {2,5} {2,4} {2,3} {1,5} {4,5} {1,3} {3,5} Kneser Graph Considered the cheapest edge, {8, 9}. with weight 76 New Features of the GraphTheory Package Animations for Prim's and Kruskal's Algorithms Below we show some key frames from the commands: > G:=AntiPrismGraph(5,2): > G

  13. Magnetovac Cylinder to Magnetovac Torus

    E-print Network

    E. N. Glass

    2006-10-18

    A method for mapping known cylindrical magnetovac solutions to solutions in torus coordinates is developed. Identification of the cylinder ends changes topology from R1 x S1 to S1 x S1. An analytic Einstein-Maxwell solution for a toroidal magnetic field in tori is presented. The toroidal interior is matched to an asymptotically flat vacuum exterior, connected by an Israel boundary layer.

  14. The Condensate from Torus Knots

    E-print Network

    A. Gorsky; A. Milekhin; N. Sopenko

    2015-06-22

    We discuss recently formulated instanton-torus knot duality in $\\Omega$-deformed 5D SQED on $\\mathbb{R}^4 \\times S^1$ focusing at the microscopic aspects of the condensate formation in the instanton ensemble. Using the chain of dualities and geometric transitions we embed the SQED with a surface defect into the $SU(2)$ SQCD with $N_f=4$ and identify the numbers $(n,m)$ of the torus $T_{n,m}$ knot as instanton charge and electric charge. The HOMFLY torus knot invariants in the fundamental representation provide entropic factor in the condensate of the massless flavor counting the degeneracy of the instanton--W-boson web with instanton and electric numbers $(n,m)$ but different spin and flavor content. Using the inverse geometrical transition we explain how our approach is related to the evaluation of the HOMFLY invariants in terms of Wilson loop in 3d CS theory. The reduction to 4D theory is briefly considered and some analogy with baryon vertex is conjectured.

  15. The plasma wave environment of Europa

    Microsoft Academic Search

    W. S. Kurth; D. A. Gurnett; A. M. Persoon; A. Roux; S. J. Bolton; C. J. Alexander

    2001-01-01

    The Galileo spacecraft has executed nine close flybys of Jupiter's moon Europa for which plasma wave observations were obtained. This paper presents an analysis of the observations from these flybys taking into consideration the variable geometry of the trajectories in an attempt to characterize the general plasma-wave environment associated with the interaction of the Jovian magnetosphere with the moon. A

  16. REVIEW OF THE NATIONAL SPHERICAL TORUS EXPERIMENT RESEARCH RESULTS

    SciTech Connect

    Mueller, D.; Menard, J. E.; Bell, M. G.; Bell, R. E.; Diem, S.; Fredrickson, E. D.; Gates, D. A.; Hill, K. W.; Hosea, J. C.; Kaye, S. M.; Kessel, C. E.; Kugel, H. W.; LeBlanc, B. P.; Mansfield, D. K.; Majeski, R. P.; Mazzucato, E.; Medley, S. S.; Myra, J. R.; Park, H. K.; Paul, S. F. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States)

    2009-07-26

    The National Spherical Torus Experiment (NSTX) produces plasmas, with toroidal aspect ratio as low as 1.25 and plasma currents up to 1.5 MA, which can be heated by up to 6 MW High-Harmonic Fast Waves and up to 7 MW of deuterium Neutral Beam Injection. With these capabilities, NSTX has already made considerable progress in advancing the scientific understanding of high performance plasmas needed for low-aspect-ratio reactor concepts and for ITER. In transport and turbulence research on NSTX, the role of magnetic shear is being elucidated in discharges in which electron energy transport barriers are observed. Scaling studies indicate a weaker dependence on plasma current than at conventional aspect ratio and a significant dependence on toroidal field (B{sub T}).

  17. Detecting nanoparticles at radio frequencies: Jovian dust stream impacts on Cassini/RPWS

    E-print Network

    Gurnett, Donald A.

    Detecting nanoparticles at radio frequencies: Jovian dust stream impacts on Cassini/RPWS N. Meyer 2008; published 7 February 2009. [1] We analyse wave observations by the Cassini/RPWS instrument at radio frequencies: Jovian dust stream impacts on Cassini/RPWS, Geophys. Res. Lett., 36, L03103, doi:10

  18. Coupling of pressure waves to clouds in the Jovian troposphere

    NASA Astrophysics Data System (ADS)

    Gaulme, P.; Mosser, B.

    2004-11-01

    The receipt for a successful study of the Jovian interior structure is given by the association of seismology and precise visible photometry. In this framework, the micro-satellite project Jovis, presented to the French space agency (Mosser et al. 2004), is for Jupiter a copy of what the Europen space mission COROT is for the stars (Baglin et al. 1998). The Jovian visible flux being dominated by the albedo map, an accurate analysis of the cloud response to a seismic wave is needed. Therefore, we have revisited the propagation of sound waves in the Jovian troposphere, in order to estimate how they affect the uppest clouds layer, composed of ammonia ice. First, considering Jupiter as a mirror, the expected variations of the reflected solar flux due to the smooth distorsions are about the ppm level for a 50 cm s-1 amplitude wave. Second, introducing thermodynamics, we determine the phase transitions induced by the waves in the clouds. These phase changes are linked to the ice particles growth, and limited by kinetics. A Mie model (Mishchenko et al 2002) associated to a simple radiation transfer model allows us to estimate that the final albedo fluctuations of the cloud perturbed by a seismic wave can reach the 70-ppm level. This gain of a factor 70 makes the phenomenon easier to observe and opens new prospectives for the seismic study of Jupiter : low amplitude modes, high degrees modes. špace{1cm} Baglin et al. 1998. 185 IAU. Symp. pp. 301. Kyoto. Mosser et al. 2004. SF2A-2004 pp. 257. EdP-Sciences, Les Ulis. Mishchenko et al. 2002. Scatt. Abs. Em. Light Small Particles pp. 158-190. Cambridge University Press.

  19. New capabilities and results for the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Bell, M. G.; Bell, R. E.; Gates, D. A.; Kaye, S. M.; Kugel, H.; LeBlanc, B. P.; Levinton, F. M.; Maingi, R.; Menard, J. E.; Raman, R.; Sabbagh, S. A.; Stutman, D.; NSTX Research Team

    2006-08-01

    The National Spherical Torus Experiment (NSTX) produces plasmas with toroidal aspect ratio as low as 1.25, which can be heated by up to 6 MW high-harmonic fast waves and up to 7 MW of deuterium neutral beam injection. Using new poloidal field coils, plasmas with cross-section elongation up to 2.7, triangularity 0.8, plasma currents Ip up to 1.5 MA and normalized currents Ip/aBT up to 7.5 MA/m·T have been achieved. A significant extension of the plasma pulse length, to 1.5 s at a plasma current of 0.7 MA, has been achieved by exploiting the bootstrap and NBI-driven currents to reduce the dissipation of poloidal flux. Inductive plasma startup has been supplemented by coaxial helicity injection (CHI) and the production of persistent current on closed flux surfaces by CHI has now been demonstrated in NSTX. The plasma response to magnetic field perturbations with toroidal mode numbers n = 1 or 3 and the effects on the plasma rotation have been investigated using three pairs of coils outside the vacuum vessel. Recent studies of both MHD stability and of transport benefitted from improved diagnostics, including measurements of the internal poloidal field using the motional Stark effect (MSE). In plasmas with a region of reversed magnetic shear in the core, now confirmed by the MSE data, improved electron confinement has been observed.

  20. Solar wind magnetic field bending of Jovian dust trajectories.

    PubMed

    Zook, H A; Grün, E; Baguhl, M; Hamilton, D P; Linkert, G; Liou, J; Forsyth, R; Phillips, J L

    1996-11-29

    From September 1991 to October 1992, the cosmic dust detector on the Ulysses spacecraft recorded 11 short bursts, or streams, of dust. These dust grains emanated from the jovian system, and their trajectories were strongly affected by solar wind magnetic field forces. Analyses of the on-board measurements of these fields, and of stream approach directions, show that stream-associated dust grain masses are of the order of 10(-18) gram and dust grain velocities exceed 200 kilometers per second. These masses and velocities are, respectively, about 10(3) times less massive and 5 to 10 times faster than earlier reported. PMID:8929405

  1. Coupling of acoustic waves to clouds in the jovian troposphere

    NASA Astrophysics Data System (ADS)

    Gaulme, Patrick; Mosser, Benoît

    2005-11-01

    Seismology is the best tool for investigating the interior structure of stars and giant planets. This paper deals with a photometric study of jovian global oscillations. The propagation of acoustic waves in the jovian troposphere is revisited in order to estimate their effects on the planetary albedo. According to the standard model of the jovian cloud structure there are three major ice cloud layers (e.g., [Atreya et al., 1999. A comparison of the atmospheres of Jupiter and Saturn: Deep atmospheric composition, cloud structure, vertical mixing, and origin. Planet Space Sci. 47, 1243-1262]). We consider only the highest layers, composed of ammonia ice, in the region where acoustic waves are trapped in Jupiter's atmosphere. For a vertical wave propagating in a plane parallel atmosphere with an ammonia ice cloud layer, we calculate first the relative variations of the reflected solar flux due to the smooth oscillations at about the ppm level. We then determine the phase transitions induced by the seismic waves in the clouds. These phase changes, linked to ice particle growth, are limited by kinetics. A Mie model [Mishchenko et al., 2002. Scattering, Absorption, and Emission of Light by Small Particles. Cambridge Univ. Press, Cambridge, pp. 158-190] coupled with a simple radiation transfer model allows us to estimate that the albedo fluctuations of the cloud perturbed by a seismic wave reach relative variations of 70 ppm for a 3-mHz wave. This albedo fluctuation is amplified by a factor of ˜70 relative to the previously published estimates that exclude the effect of the wave on cloud properties. Our computed amplifications imply that jovian oscillations can be detected with very precise photometry, as proposed by the microsatellite JOVIS project, which is dedicated to photometric seismology [Mosser et al., 2004. JOVIS: A microsatellite dedicated to the seismic analysis of Jupiter. In: Combes, F., Barret, D., Contini, T., Meynadier, F., Pagani, L. (Eds.), SF2A-2004, Semaine de l'Astrophysique Francaise, Les Ulis. In: EdP-Sciences Conference Series, pp. 257-258].

  2. 1979J2 - Discovery of a previously unknown Jovian satellite

    NASA Technical Reports Server (NTRS)

    Synnott, S. P.

    1980-01-01

    Detailed examination of imaging data of Jupiter taken by Voyager 1 reveals a previously unknown satellite 1979J2. Analysis of the image on the Jovian disk indicates that it is not an atmospheric feature or the shadow of any known satellite. The orbital period is calculated at 16 hours 11 minutes 21.25 seconds + or - 0.5 second and the semimajor axis is 3.1054 Jupiter radii. The observed profile is roughly circular with a diameter of 80 kilometers. An albedo of approximately 0.05 is reported, which is similar to Amalthea's. The geometry of the observational situation is illustrated.

  3. Clouds, aerosols, and photochemistry in the Jovian atmosphere

    NASA Astrophysics Data System (ADS)

    West, R. A.; Strobel, D. F.; Tomasko, M. G.

    1986-03-01

    An assessment is made of the development status of concepts for cloud and aerosol compositions, vertical and horizontal distributions, and microphysical properties, in the Jovian upper troposphere and stratosphere. Attention is given to several key photochemical species' relationships to aerosol formation as well as their transport process implications, treating photochemistry in the context of comparative planetology and noting differences and similarities among the outer planet atmospheres; since this approach emphasizes observational data, a variegated assortment of ground-based and spacecraft observations is assembled. Current views on the tropospheric distribution of clouds are challenged, and a rationale is presented for alternative accounts.

  4. Clouds, aerosols, and photochemistry in the Jovian atmosphere

    NASA Technical Reports Server (NTRS)

    West, R. A.; Strobel, D. F.; Tomasko, M. G.

    1986-01-01

    An assessment is made of the development status of concepts for cloud and aerosol compositions, vertical and horizontal distributions, and microphysical properties, in the Jovian upper troposphere and stratosphere. Attention is given to several key photochemical species' relationships to aerosol formation as well as their transport process implications, treating photochemistry in the context of comparative planetology and noting differences and similarities among the outer planet atmospheres; since this approach emphasizes observational data, a variegated assortment of ground-based and spacecraft observations is assembled. Current views on the tropospheric distribution of clouds are challenged, and a rationale is presented for alternative accounts.

  5. A dawn-to-dusk electric field in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Ip, W.-H.; Goertz, C. K.

    1984-01-01

    It is shown that if Io-injected plasma is lost via a planetary wind a sun-fixed Birkeland current system may result. This is due to the fact that a current flows across a density gradient produced by the loss of plasma through the planetary wind in the tail. The divergent current is connected to field-aligned Birkeland currents which flow into the ionosphere at dawn and out of it at dusk. The closure currents in the ionosphere require a dawn-to-dusk electric field which at the orbit of Io is estimated to have a strength of a few mV/m. Independent estimates derived from the local time asymmetry of the torus u.v. emission indicate a field of 1.5 mV/m.

  6. SED Signatures of Jovian Planets Around White Dwarf Stars

    E-print Network

    R. Ignace

    2001-06-28

    The problem of detecting Jovian-sized planets orbiting White Dwarf stars is considered. Significant IR excesses result from warm Jupiters orbiting a White Dwarf of $T_{\\rm eff}=10000$ K at a distance of $\\sim 10^3$ White Dwarf radii (corresponding to $\\sim 10^2$ Jupiter radii or a few tenths of an AU) with an orbital period of $\\sim 100$ days. Such a planet will have a 10 micron flux density at its Wien peak that is comparable to the emission of the White Dwarf at that wavelength. Although the White Dwarf is much hotter than the planet, the planet will have peak brightness at the IR, well into the Rayleigh-Jeans tail of the White Dwarf, plus Jovians are about 10 times larger than White Dwarfs, so there is a substantial gain in the planet to star brightness contrast as compared to planets around Main Sequence stars. In the solar neighborhood, there are 51 White Dwarf stars within 13 pc of the Sun. At 10 pc, the IR flux density of ``warm'' Jupiters (a few hundred Kelvin) will fall in the range 10--100 micro-Jansky which should be observable with {\\it SIRTF}.

  7. Studies of thermal wave phenomena on the Jovian planets

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    1991-01-01

    Ground based and Voyager observations of Jupiter have provided evidence that the tropospheric temperature shows global scale longitudinal variations which are often wavelike in character. Voyager data are reported to exhibit the presence of slowly moving thermal features, wherein the jovian tropospheric temperature patterns are not advected by the equatorial zonal winds, but are not found to rotate at the System III (interior) rate. Ground based data in a broad infrared band (8 to 13 micron) show a wavelike structure whose amplitude and spatial scale are similar to the reported properties of the slowly moving thermal features. This study is directed toward obtaining additional ground based data in infrared spectral bands whose contribution functions are optimized for specific atmospheric regions (tropospheric at 20 micron, and stratospheric at 7.8 micron), in order to confirm the previous results, and to identify the nature and physical significance of wavelike longitudinal temperature fluctuations on the Jovian planets. A 2-D infrared array detector and low resolution cryogenic grating spectrometer is being adapted to obtain maps in approx. 2/cm bandpasses.

  8. New attempt of detection of the Jovian oscillations

    NASA Astrophysics Data System (ADS)

    Mosser, B.; Maillard, J. P.; Mekarnia, D.

    1999-09-01

    We report a new seismic observation of Jupiter in August 1996 with the Fourier transform spectrometer, based at the CFH telescope, used as an accelerometer. With this instrument, the Jovian velocity field could be measured for the first time with an absolute velocity calibration: the Doppler effect translates into a phase shift which is a fraction of a reference laser wavelength. The noise in the Fourier spectrum reaches 4 cm.s(-1}.muHz ({-1/2)) . A source of noise, identified as due to spurious velocity signal induced by the seeing effect on the rapidly rotating planet, as well as a poor window function, has precluded the possible direct identification of Jovian modes. However, there is a strong evidence in the data for an oscillation characteristic frequency nu_0 , at 142+/- 3mu Hz, which confirms a low value of this parameter. Furthermore, the identification of the large splittings along the whole Fourier spectrum indicates a very small planetary core, if any. The modes amplitude is inferred not to exceed 0.6 m.s(-1) in the [1-3 mHz] frequency range.

  9. Infrared observations of the jovian system from voyager 2.

    PubMed

    Hanel, R; Conrath, B; Flasar, M; Herath, L; Kunde, V; Lowman, P; Maguire, W; Pearl, J; Pirraglia, J; Samuelson, R; Gautier, D; Gierasch, P; Horn, L; Kumar, S; Ponnamperuma, C

    1979-11-23

    Infrared spectra obtainedfrom Voyager 2 have provided additional data on the Jovian system, complementing those obtained from Voyager 1. The abundance ratio of ethane to acetylene in Jupiter's atmosphere appears to be about three times larger in the polar regions than at lower latitudes. A decidedly hemispherical asymmetry exists, with somewhat higher ratios prevailing in northern latitudes. An overall increase in the abundance ratio by a factor of about 1.7 appears to have occurred between the Voyager 1 and 2 encounters. Global brightness temperature maps of Jupiter at 226 and 602 cm(-1) exhibit a large amount of local- and planetary-scale structure, as well as temporal variability. Although heterogeneous cloud structure and ammonia concentration in the lower troposphere may contribute to the appearance of the 226-cm(-1) map, the detail in the 602-cm(-1) maps probably represents the actual horizontal thermal structure near the tropopause and suggests that dynamical heating and cooling processes are important. Low-latitude surface temperatures on the Galilean satellites rangefrom approximately 80 K on the dark sides to 155 K at the subsolar point on Callisto. Below a thin insulating layer, the thermal inertia of Callisto is somewhat greater than that of Earth's moon. Upper limits on the infrared optical depth of the Jovian ring rangingfrom approximately 3 x 10(-4) at 250 cm(-1) to 3 x 10(-3) at 600 cm(-1) have been found. PMID:17733912

  10. Physics Results from the National Spherical Torus Experiment

    SciTech Connect

    M.G. Bell for the NSTX Research Team

    2004-07-08

    The National Spherical Torus Experiment (NSTX) produces plasmas with aspect ratio A {triple_bond} R/a = 0.85m/0.68m {approx} 1.25, at plasma currents up to 1.5 MA with vacuum toroidal magnetic field up to 0.6 T on axis. The plasmas are heated by up to 6 MW of High-Harmonic Fast Waves (HHFW) at a frequency 30 MHz and by 7 MW of deuterium Neutral Beam Injection (NBI) at an energy up to 100 keV. Since January 2004, NSTX has been operating, routinely at toroidal fields up to 0.45 T, with a new central conductor bundle in the toroidal field coil.

  11. AGN torus properties with WISE

    NASA Astrophysics Data System (ADS)

    Nikutta, Robert; Nenkova, Maia; Ivezi?, Željko; Hunt-Walker, Nicholas; Elitzur, Moshe

    2014-07-01

    The Wide-field Infrared Survey Explorer (WISE) has scanned the entire sky with unprecedented sensitivity in four infrared bands, at 3.4, 4.6, 12, and 22 ?m. The WISE Point Source Catalog contains more than 560 million objects, among them hundreds of thousands of galaxies with Active Nuclei (AGN). While type 1 AGN, owing to their bright and unobscured nature, are easy to detect and constitute a rather complete and unbiased sample, their type 2 counterparts, postulated by AGN unification, are not as straightforward to identify. Matching the WISE catalog with known QSOs in the Sloan Digital Sky Survey we confirm previous identification of the type 1 locus in the WISE color space. Using a very large database of the popular Clumpy torus models, we find the colors of the putative type 2 counterparts, and also, for the first time, predict their number vs. flux relation that can be expected to be observed in any given WISE color range. This will allow us to put statistically very significant constraints on the torus parameters. Our results are a successful test of the AGN unification scheme.

  12. Status of the control system on the National Spherical Torus Experiment (NSTX)

    E-print Network

    Princeton Plasma Physics Laboratory

    #61 final Status of the control system on the National Spherical Torus Experiment (NSTX) D. A acquisition, which uses the FPDP (Front Panel Data Port) protocol, is measured to be ~8microseconds. A Stand development. Keywords: Plasma control, real-time electronics, software structure 1. Introduction The National

  13. Dissipation and turbulent heating of plasma in Jupiter's magnetosphere

    NASA Astrophysics Data System (ADS)

    Barbosa, D. D.

    1981-10-01

    Voyager 1 observations of plasma waves in the dayside Jovian magnetosphere which show a correlation with measurements of localized concentrations of cool thermal plasma are presented. This moderately intense broadband electrostatic noise is shown to be of sufficient intensity to accelerate superthermal ions to energies approximately 1 keV and higher. This process can account for the extensive heating of plasma in the magnetosphere and can energize a fraction of heavy ions to injection threshold for a high-energy second stage acceleration mechanism. A brief discussion of the relation of this noise to Jovian magnetospheric dynamics is included.

  14. Wave-clouds coupling in the Jovian troposphere.

    NASA Astrophysics Data System (ADS)

    Gaulme, P.; Mosser, B.

    2003-05-01

    First studies about Jovian oscillations are due to Vorontsov et al. (1976). Attempts to observe them started in the late 1980's (Deming et al. 1989, Mosser et al. 1991). The micro-satellite Jovis and ground-based observations campaign such as SŸMPA (e.g Baglin et al. 1999) account for an accurate analysis of the cloud response to an acoustic wave. Therefore, the propagation of sound or gravity waves in the Jovian troposphere is revisited, in order to estimate their effect on the highest clouds layer. From basic thermodynamics, the troposphere should be stratified in three major ice clouds layers: water-ammonia, ammonium-hydrosulfide and ammonia ice for the highest. The presence of ammonia ice clouds has been inferred from Kuiper in 1952, and was predicted to dominate the Jovian skies. However, they had been observed spectroscopically over less than one percent of the surface. This absence of spectral proof could come from a coating of ammonia particles from other substances (Baines et al. 2002). In this work, we study the behaviour of a cloud submitted to a periodic pressure perturbation. We suppose a vertical wave propagating in a plane parallel atmosphere including an ammonia ice cloud layer. We determine the relation between the Lagrangian pressure perturbation and the variation of the fraction of solid ammonia. The linearized equations governing the evolution of the Eulerian pressure and density perturbed terms allows us to study how the propagation is altered by the clouds and how the clouds move with the wave. Finally, because a pressure perturbation modifies the fraction of solid ammonia, we estimate how much an ammonia crystal should grow or decrease and how the clouds albedo could change with the wave. Baglin et al. 1999. BAAS 31, 813. Baines et al. 2002. Icarus 159, 74. Deming et al. 1989. Icarus 21, 943. Kuiper 1952.The atmospheres of the Earth and Planets pp. 306-405. Univ. of Chicago Press, Chicago. Mosser et al. 1991. A&A 251, 356. Vorontsov et al. 1976. Icarus 27, 109.

  15. Confinement of Neutral Beam Ions in the National Spherical Torus Experiment

    SciTech Connect

    D.S. Darrow; S.S. Medley; A.L. Roquemore; A. Rosenberg

    2001-12-18

    The loss of neutral-beam ions to the wall has been measured in the National Spherical Torus Experiment (NSTX) by means of thermocouples, an infrared (IR) camera, and a Faraday cup probe. The losses tend to exhibit the expected dependences on plasma current, tangency radius of the injector, and plasma outer gap. However, the thermocouples and the Faraday cups indicate substantially different levels of loss and this difference has yet to be understood.

  16. A convected kappa distribution model for hot ions in the Jovian magnetodisc

    NASA Technical Reports Server (NTRS)

    Kane, M.; Mauk, B. H.; Keath, E. P.; Krimigis, S. M.

    1992-01-01

    Hot ion angular anisotropies measured by the Low Energy Charged Particle (LECP) instrument during the Voyager 2 encounter with the Jovian dayside outer magnetosphere (60-30 RJ) have been fitted to a 2 species convected kappa distribution function using a nonlinear least squares technique. The resulting parameters are well constrained by the data. The heavy ion species was assumed to be either sulfur or oxygen of unknown charge. The light species was assumed to be protons. The bulk flow speeds deduced from the model were found, contrary to some theories, to increase with increasing radial distance from Jupiter within the radial region addressed, remaining a substantial fraction (0.6) of the rigid corotation speed. Agreement with the averaged Voyager Plasma Science results was obtained near 30 RJ. The core Maxwellian temperature of the heavy ion distribution functions (30-100 keV) increased with increasing radial distance, following the trend anticipated from the corotation pickup of heavy ions. The proton temperature (20 keV) remained nearly constant.

  17. The zonal distribution of hydrogen in the Jovian atmosphere

    NASA Technical Reports Server (NTRS)

    Killen, R. M.; Chamberlain, J. W.

    1984-01-01

    The Lyman-alpha intensities measured by Voyagers 1 and 2 and by the IUE are used as the bases of deductions for the distribution of atomic hydrogen in the Jovian atmosphere, under the assumption that the sources of the dayside Lyman alpha include resonance scattering of solar Lyman alpha, resonance scattering of the interplanetary Lyman-alpha radiation, and direct excitation by charged particles. The daytime equation of radiative transfer is solved to determine the longitudinal distribution of freely scattering atomic hydrogen that would account for the observed flux. This solution indicates that if the hydrogen bulge is due to localized heating and a consequent increase in scale height, the perturbed region temperature must be about 100 K warmer than that in the normal region. The H distribution derived from the dayside solution is used with the nightside flux to estimate the longitude variation of particle precipitation on the nightside.

  18. Electric discharge synthesis of HCN in simulated Jovian atmospheres

    NASA Technical Reports Server (NTRS)

    Stribling, Roscoe; Miller, Stanley L.

    1987-01-01

    Corona discharge is presently considered as a possible source of the HCN detected in the Jovian atmosphere at 2.2 x 10 to the -7th moles/sq cm column density, for the cases of gas mixtures containing H2, CH4, and NH3, with H2/CH4 ratios from 4.4 to 1585. A 3:1 ratio of corona discharge to lightning energy similar to that of the earth is applied to Jupiter. Depending on the lightning energy available on Jupiter and the eddy diffusion coefficients in the synthesis region, HCN column densities generated by corona discharge could account for about 10 percent of the HCN observed.

  19. High resolution remote sensing observations for missions to the Jovian system: Io as a case study

    E-print Network

    California at Berkeley, University of

    , USA d Exploration Sciences, P.O. Box 24, Pine, CO 80470, USA e Lockheed Martin Advanced Technology the approach to the Jovian system and subsequently from orbit around Europa or Ganymede, in both the visible

  20. Low Energy Particle Oscillations and Correlations with Hydromagnetic Waves in the Jovian Magnetosphere: Ulysses Measurements

    NASA Technical Reports Server (NTRS)

    Krupp, N.; Tsurutani, B. T.; Lanzerotti, L. J.; Maclennan, C. G.

    1996-01-01

    We report on measurements of energetic particle modulations observed by the HI-SCALE instrument aboard the Ulysses Spacecraft that were associated with the only hydromagnetic wave event measured inside the Jovian magnetosphere by the Ulysses magnetometer investigation.

  1. Jovian electron propagation in three dimensions of the heliosphere: The Ulysses investigations

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Smith, D. A.; Zhang, M.

    1993-01-01

    We report investigations of Jovian relativistic electrons in the interplanetary medium that provide new insights into both the physical processes by which the Jovian magnetosphere releases its trapped, relativistic electrons into the interplanetary medium, and the modes of their interplanetary propagation. These studies were dependent on the unique postencounter trajectory for Ulysses. The spacecraft remained close to the radial distance of Jupiter (approximately 5.2 AU) and moved southward on the duskside by only approximately 12 deg in heliographic latitude and less than 8 deg in the heliographic azimuth relative to Jupiter for the period of approximately 100 deg days of this study. During this period the nominal Parker spiral interplanetary magnetic field with its alternating polarities sector structure established direct magnetic field line connections frequently between Jupiter and the spacecraft. These unique conditions made it possible to investigate in detail, for approximately four solar rotations, both the Jovian electron burst phenomenon and the continuous, diffusive interplanetary propagation of Jovian electrons.

  2. Initial physics results from the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Kaye, S. M.; Bell, M. G.; Bell, R. E.; Bialek, J.; Bigelow, T.; Bitter, M.; Bonoli, P.; Darrow, D.; Efthimion, P.; Ferron, J.; Fredrickson, E.; Gates, D.; Grisham, L.; Hosea, J.; Johnson, D.; Kaita, R.; Kubota, S.; Kugel, H.; LeBlanc, B.; Maingi, R.; Manickam, J.; Mau, T. K.; Maqueda, R. J.; Mazzucato, E.; Menard, J.; Mueller, D.; Nelson, B.; Nishino, N.; Ono, M.; Paoletti, F.; Paul, S.; Peng, Y.-K. M.; Phillips, C. K.; Raman, R.; Ryan, P.; Sabbagh, S. A.; Schaffer, M.; Skinner, C. H.; Stutman, D.; Swain, D.; Synakowski, E.; Takase, Y.; Wilgen, J.; Wilson, J. R.; Zhu, W.; Zweben, S.; Bers, A.; Carter, M.; Deng, B.; Domier, C.; Doyle, E.; Finkenthal, M.; Hill, K.; Jarboe, T.; Jardin, S.; Ji, H.; Lao, L.; Lee, K. C.; Luhmann, N.; Majeski, R.; Medley, S.; Park, H.; Peebles, T.; Pinsker, R. I.; Porter, G.; Ram, A.; Rensink, M.; Rognlien, T.; Stotler, D.; Stratton, B.; Taylor, G.; Wampler, W.; Wurden, G. A.; Xu, X. Q.; Zeng, L.

    2001-05-01

    The mission of the National Spherical Torus Experiment (NSTX) is to extend the understanding of toroidal physics to low aspect ratio (R/a?1.25) in low collisionality regimes. NSTX is designed to operate with up to 6 MW of high harmonic fast wave (HHFW) heating and current drive, 5 MW of neutral beam injection (NBI) and co-axial helicity injection (CHI) for noninductive startup. Initial experiments focused on establishing conditions that will allow NSTX to achieve its aims of simultaneous high ?t and high-bootstrap current fraction, and to develop methods for noninductive operation, which will be necessary for Spherical Torus power plants. Ohmic discharges with plasma currents up to 1 MA and with a range of shapes and configurations were produced. Density limits in deuterium and helium reached 80% and 120% of the Greenwald limit, respectively. Significant electron heating was observed with up to 2.3 MW of HHFW. Up to 270 kA of toroidal current for up to 200 ms was produced noninductively using CHI. Initial NBI experiments were carried out with up to two beam sources (3.2 MW). Plasmas with stored energies of up to 140 kJ and ?t=21% were produced.

  3. Initial Physics Results From the National Spherical Torus Experiment

    SciTech Connect

    Kaye, S.M.; Bell, M.G.; Bell, R.E.; Bialek, J. [and others

    2001-01-03

    The mission of the National Spherical Torus Experiment (NSTX) is to extend the understanding of toroidal physics to low aspect ratio (R/a approximately equal to 1.25) in low collisionality regimes. NSTX is designed to operate with up to 6 MW of High Harmonic Fast Wave (HHFW) heating and current drive, 5 MW of Neutral Beam Injection (NBI) and Co-Axial Helicity Injection (CHI) for non-inductive startup. Initial experiments focused on establishing conditions that will allow NSTX to achieve its aims of simultaneous high-bt and high-bootstrap current fraction, and to develop methods for non-inductive operation, which will be necessary for Spherical Torus power plants. Ohmic discharges with plasma currents up to 1 MA and with a range of shapes and configurations were produced. Density limits in deuterium and helium reached 80% and 120% of the Greenwald limit respectively. Significant electron heating was observed with up to 2.3 MW of HHFW. Up to 270 kA of toroidal current for up to 200 msec was produced noninductively using CHI. Initial NBI experiments were carried out with up to two beam sources (3.2 MW). Plasmas with stored energies of up to 140 kJ and bt =21% were produced.

  4. PROBING THE LARGE-SCALE TOPOLOGY OF THE HELIOSPHERIC MAGNETIC FIELD USING JOVIAN ELECTRONS

    SciTech Connect

    Owens, M. J.; Horbury, T. S. [Space and Atmospheric Physics, Imperial College, London SW7 2AZ (United Kingdom); Arge, C. N. [Air Force Research Laboratory/Space Vehicles Directorate, Kirtland Air Force Base, NM 87117 (United States)

    2010-05-10

    Jupiter's magnetosphere acts as a point source of near-relativistic electrons within the heliosphere. In this study, three solar cycles of Jovian electron data in near-Earth space are examined. Jovian electron intensity is found to peak for an ideal Parker spiral connection, but with considerable spread about this point. Assuming the peak in Jovian electron counts indicates the best magnetic connection to Jupiter, we find a clear trend for fast and slow solar wind to be over- and under-wound with respect to the ideal Parker spiral, respectively. This is shown to be well explained in terms of solar wind stream interactions. Thus, modulation of Jovian electrons by corotating interaction regions (CIRs) may primarily be the result of changing magnetic connection, rather than CIRs acting as barriers to cross-field diffusion. By using Jovian electrons to remote sensing magnetic connectivity with Jupiter's magnetosphere, we suggest that they provide a means to validate solar wind models between 1 and 5 AU, even when suitable in situ solar wind observations are not available. Furthermore, using Jovian electron observations as probes of heliospheric magnetic topology could provide insight into heliospheric magnetic field braiding and turbulence, as well as any systematic under-winding of the heliospheric magnetic field relative to the Parker spiral from footpoint motion of the magnetic field.

  5. Plasma control at JET

    Microsoft Academic Search

    M. Lennholm; T. Budd; R. Felton; M. Gadeberg; A. Goodyear; F. Milani; F. Sartori

    2000-01-01

    Joint European Torus (JET) discharges have plasma currents up to 6 MA and toroidal fields up to 4 T. The plasma parameters during discharges are determined by the action of a number of distinct systems. These systems can be divided into three groups; the toroidal and poloidal field systems; the fuelling systems; and the additional heating systems. The systems can

  6. Radio and Plasma Wave Science Opportunities Afforded by the Jupiter Icy Moons Orbiter

    Microsoft Academic Search

    W. S. Kurth; D. A. Gurnett; W. M. Farrell; M. D. Desch; M. L. Kaiser; P. Zarka; A. Lecacheux; P. Canu; S. J. Bolton; J. E. Wahlund; L. G. Blomberg; S. D. Bale; M. Moncuquet

    2003-01-01

    The Galileo mission demonstrated the extensive and varied interactions between the Jovian magnetosphere and the icy Galilean satellites. In particular, the Galileo plasma wave investigation showed the surprisingly complex array of plasma and radio wave phenomena accompanying Ganymede's magnetosphere, evidence of an extensive magnetospheric interaction at Europa, and a weaker yet highly variable interaction at Callisto. The plasma wave observations

  7. Dusty plasmas in the solar system

    Microsoft Academic Search

    C. K. Goertz

    1989-01-01

    The processes that lead to charging of dust grains in a plasma are briefly reviewed. Whereas for single grains the results have been long known, the reduction of the average charge on a grain by 'Debye screening' has only recently been discovered. This reduction can be important in the Jovian ring and in the rings of Uranus. The emerging field

  8. Theory and observations of electrostatic ion waves in the cold Io torus

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.; Kurth, W. S.

    1990-01-01

    A study of the ELF plasma wave environment of the cold Io torus in Jupiter's magnetosphere is made. Voyager 1 data are presented which show three distinct types of electrostatic ion waves occurring there: the Buchsbaum ion-ion mode just below the proton cyclotron frequency f(cp), hydrogen Bernstein modes at (n + 1/2) f(cp), and lower hybrid waves near f(LHR). The presence of these waves at their characteristic frequencies is consistent with a predominantly heavy ion plasma composed of singly ionized sulfur and oxygen ions along with a small admixture of protons. The hydrogen Bernstein modes are tightly confined to the magnetic equator, occurring within + or - 4 deg of it, while the Buchsbaum mode is localized to the dense heavy ion plasma of the cold torus near the centrifugal equator. A general theory for excitation of the waves based on the ion pickup process is developed.

  9. Development of internal magnetic probe for current density profile measurement in Versatile Experiment Spherical Torus

    NASA Astrophysics Data System (ADS)

    Yang, J.; Lee, J. W.; Jung, B. K.; Chung, K. J.; Hwang, Y. S.

    2014-11-01

    An internal magnetic probe using Hall sensors to measure a current density profile directly with perturbation of less than 10% to the plasma current is successfully operated for the first time in Versatile Experiment Spherical Torus (VEST). An appropriate Hall sensor is chosen to produce sufficient signals for VEST magnetic field while maintaining the small size of 10 mm in outer diameter. Temperature around the Hall sensor in a typical VEST plasma is regulated by blown air of 2 bars. First measurement of 60 kA VEST ohmic discharge shows a reasonable agreement with the total plasma current measured by Rogowski coil in VEST.

  10. Development of internal magnetic probe for current density profile measurement in Versatile Experiment Spherical Torus.

    PubMed

    Yang, J; Lee, J W; Jung, B K; Chung, K J; Hwang, Y S

    2014-11-01

    An internal magnetic probe using Hall sensors to measure a current density profile directly with perturbation of less than 10% to the plasma current is successfully operated for the first time in Versatile Experiment Spherical Torus (VEST). An appropriate Hall sensor is chosen to produce sufficient signals for VEST magnetic field while maintaining the small size of 10 mm in outer diameter. Temperature around the Hall sensor in a typical VEST plasma is regulated by blown air of 2 bars. First measurement of 60 kA VEST ohmic discharge shows a reasonable agreement with the total plasma current measured by Rogowski coil in VEST. PMID:25430222

  11. First observation of ELM pacing with vertical jogs in a spherical torus

    SciTech Connect

    Gerhardt, S.P. [Princeton Plasma Physics Laboratory (PPPL); Ahn, Joon-Wook [Oak Ridge National Laboratory (ORNL); Canik, John [ORNL; Maingi, R. [Oak Ridge National Laboratory (ORNL); Bell, R. [Princeton Plasma Physics Laboratory (PPPL); Gates, D. [Princeton Plasma Physics Laboratory (PPPL); Goldston, R. [Princeton Plasma Physics Laboratory (PPPL); Hawryluk, R. [Princeton Plasma Physics Laboratory (PPPL); Le Blanc, B. P. [Princeton Plasma Physics Laboratory (PPPL); Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Sontag, Aaron C [ORNL; Sabbagh, S. A. [Columbia University; Tritz, K. [Johns Hopkins University

    2010-01-01

    Experiments in a number of conventional aspect ratio tokamaks have been successful in pacing edge localized modes (ELMs) by rapid vertical jogging of the plasma. This paper demonstrates the first pacing of ELMs in a spherical torus plasma. Applied 30 Hz vertical jogs synchronized the ELMs with the upward motion of the plasma. 45 Hz jogs also lead to an increase in the ELM frequency, though the synchronization of the ELMs and jogs was unclear. A reduction in the ELM energy was observed at the higher driven ELM frequencies.

  12. Jovian seismology: preliminary results of the SYMPA instrument

    NASA Astrophysics Data System (ADS)

    Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Jeanneaux, F.; Alvarez, M.; Reyes, M.; Valtier, J. C.; Fossat, E.; Palle, P. L.; Belmonte, J. C.; Gelly, B.

    2006-06-01

    Jupiter's internal structure is poorly known (Guillot et al. 2004). Seismology is a powerful tool to investigate the internal structure of planets and stars, by analyzing how acoustic waves propagate. Mosser (1997) and Gudkova & Zarkhov (1999) showed that the detection and the identification of non-radial modes up to degree ?=25 can constrain strongly the internal structure. SYMPA is a ground-based network project dedicated to the Jovian oscillations (Schmider et al. 2002). The instrument is composed of a Mach-Zehnder interferometer producing four interferograms of the planetary spectrum. The combination of the four images in phase quadrature allows the reconstruction of the incident light phase, which is related to the Doppler shift generated by the oscillations. Two SYMPA instruments were built at the Nice university and were used simultaneously during two observation campaigns, in 2004 and 2005, at the San Pedro Martir observatory (Mexico) and the Teide observatory (Las Canarias). We will present for the first time the data processing and the preliminary results of the experiment.

  13. Jovian seismology: preliminary results of the SYMPA instrument

    NASA Astrophysics Data System (ADS)

    Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Jeanneaux, F.; Fossat, E.; Valtier, J. C.; Alvarez, M.; Reyes, M.

    2007-06-01

    Jupiter's internal structure is poorly known (Guillot et al. 1997). Seismology is a powerful tool to investigate the internal structure of planets and stars, by analysing how acoustic waves propagate. Mosser (1997) and Gudkova & Zarkhov (1999) showed that the detection and the identification of non-radial modes up to degree ?=25 can constrain strongly the internal structure. SYMPA is a ground-based network project dedicated to the Jovian oscillations (Schmider et al. 2002). The instrument is composed of a Mach-Zehnder interferometer which produces four interferograms of the planetary spectrum. The combination of the four images in phase quadrature allows the reconstruction of the incident light phase, which is related to the Doppler shift generated by the oscillations. Two SYMPA instruments were built at the Nice university and were used simultaneously during two observation campaigns, in 2004 and 2005, at the San Pedro Martir Observatory (Mexico) and the Izana Observatory (Las Canarias). We present for the first time the data processing and the preliminary results of the experiment.

  14. Convective forcing of global circulations on the Jovian planets

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    1986-01-01

    Examples of convection in rotating layers are presented to illustrate how convection can drive global circulations on the Jovian planets. For rapid rotation the convective motions become largely two-dimensional and produce Reynold stresses which drive large scale flows. The initial tendency is to produce a prograde equatorial jet and a meridional circulation which is directed toward the poles in the surface layers. Fully nonlinear numerical simulations for the slowly rotating solar convection zone show that the meridional circulation does not reach the poles. Instead a multicellular meridional circulation is produced which has a downward flowing branch in the mid-latitudes. For more rapidly rotating objects such as Jupiter and Saturn this meridional circulation may consist of a larger number of cells. Axisymmetric convective models then show that prograde jets form at the downflow latitudes. A nonlinear numerical simulation of convection in a prograde jet is presented to illustrate the interactions which occur between convection and these jets. Without rotation the convection removes energy and momentum from the jet. With rotation the convection feeds energy and momentum into the jet.

  15. WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy

    E-print Network

    Grav, Tommy; Bauer, James M; Masiero, Joe R; Nugent, Carrie R

    2012-01-01

    We present updated/new thermal model fits for 478 Jovian Trojan asteroids observed with the Wide-field Infrared Survey Explorer (WISE). Using the fact that the two shortest bands used by WISE, centered on 3.4 and $4.6\\mu$m, are dominated by reflected light, we derive albedos of a significant fraction of these objects in these bands. While the visible albedos of both the C-, P- and D-type asteroids are strikingly similar, the WISE data reveal that the albedo at $3.4\\mu$m is different between C-/P- and D-types. The albedo at 3.4$\\mu$m can be thus be used to classify the objects, with C-/P-types having values less than 10%, and D-types have values larger than 10%. Classifying all objects larger than 50km shows that the D-type objects dominate both the leading cloud ($L_4$), with a fraction of 84%, and trailing cloud ($L_5$), with a fraction of 71-80%. The two clouds thus have very similar taxonomic distribution for these large objects, but the leading cloud has a larger number of of these large objects, $L_4/L_5...

  16. JOVIAN EARLY BOMBARDMENT: PLANETESIMAL EROSION IN THE INNER ASTEROID BELT

    SciTech Connect

    Turrini, D.; Coradini, A.; Magni, G., E-mail: diego.turrini@ifsi-roma.inaf.it [Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Via Fosso del Cavaliere 100, 00133, Rome (Italy)

    2012-05-01

    The asteroid belt is an open window on the history of the solar system, as it preserves records of both its formation process and its secular evolution. The progenitors of the present-day asteroids formed in the Solar Nebula almost contemporary to the giant planets. The actual process producing the first generation of asteroids is uncertain, strongly depending on the physical characteristics of the Solar Nebula, and the different scenarios produce very diverse initial size-frequency distributions (SFDs). In this work, we investigate the implications of the formation of Jupiter, plausibly the first giant planet to form, on the evolution of the primordial asteroid belt. The formation of Jupiter triggered a short but intense period of primordial bombardment, previously unaccounted for, which caused an early phase of enhanced collisional evolution in the asteroid belt. Our results indicate that this Jovian Early Bombardment caused the erosion or the disruption of bodies smaller than a threshold size, which strongly depends on the SFD of the primordial planetesimals. If the asteroid belt was dominated by planetesimals less than 100 km in diameter, the primordial bombardment would have caused the erosion of bodies smaller than 200 km in diameter. If the asteroid belt was instead dominated by larger planetesimals, the bombardment would have resulted in the destruction of bodies as big as 500 km.

  17. A normal-mode approach to Jovian atmospheric dynamic

    NASA Technical Reports Server (NTRS)

    Achterberg, Richard K.; Ingersoll, Andrew P.

    1989-01-01

    A nonlinear, quasi-geostrophic, baroclinic model of Jovian atmospheric dynamics is proposed, in which vertical variations of velocity are represented by a truncated sum over a complete set of orthogonal functions obtained by a separation of variables of the linearized quasi-geostrophic potential vorticity equation. A set of equations for the time variation of the mode amplitudes in the nonlinear case is then derived. It is shown that, for a planet with a neutrally stable, fluid interior instead of a solid lower boundary, the barotropic mode represents motions in the interior, and is not affected by the baroclinic modes. One consequence of this is that a normal-mode model with one baroclinic mode is dynamically equivalent to a one-layer model with solid lower topography. It is also shown that, for motions in Jupiter's cloudy lower troposphere, the stratosphere behaves nearly as a rigid lid, so that the normal-mode is applicable to Jupiter. The accuracy of the normal-mode model for Jupiter is tested using the following simple problems: (1) forced, vertically propagating Rossby waves, using two and three baroclinic modes, and (2) baroclinic instability, using two baroclinic modes. It is found that the normal-mode model provides qualitatively correct results, even with only a very limited number of vertical degrees of freedom.

  18. Engineering design of the National Spherical Torus Experiment

    SciTech Connect

    C. Neumeyer; P. Heitzenroeder; J. Spitzer, J. Chrzanowski; et al

    2000-05-11

    NSTX is a proof-of-principle experiment aimed at exploring the physics of the ``spherical torus'' (ST) configuration, which is predicted to exhibit more efficient magnetic confinement than conventional large aspect ratio tokamaks, amongst other advantages. The low aspect ratio (R/a, typically 1.2--2 in ST designs compared to 4--5 in conventional tokamaks) decreases the available cross sectional area through the center of the torus for toroidal and poloidal field coil conductors, vacuum vessel wall, plasma facing components, etc., thus increasing the need to deploy all components within the so-called ``center stack'' in the most efficient manner possible. Several unique design features have been developed for the NSTX center stack, and careful engineering of this region of the machine, utilizing materials up to their engineering allowables, has been key to meeting the desired objectives. The design and construction of the machine has been accomplished in a rapid and cost effective manner thanks to the availability of extensive facilities, a strong experience base from the TFTR era, and good cooperation between institutions.

  19. Hopkins Ultraviolet Telescope determination of the Io torus electron temperature

    NASA Technical Reports Server (NTRS)

    Hall, D. T.; Bednar, C. J.; Durrance, S. T.; Feldman, P. D.; Mcgrath, M. A.; Moos, H. W.; Strobel, D. F.

    1994-01-01

    Sulfur ion emissions from the Io plasma torus observed by the Hopkins Ultraviolet Telescope (HUT) in 1990 December have been analyzed to determine the effective temperature of the exciting electrons. Spectra were obtained with a long slit that extended from 3.1 to 8.7 Jupiter radii R(sub J) on both dawn and dusk torus ansae. The average temperature of electrons exciting S(2+) emissions from the dawn ansa is (4800 +/- 2400) K lower than on the dusk ansa, a dawn-dusk asymmetry comparable in both sign and magnitude to that measured by the Voyager Ultraviolet Spectrograph (UVS) experiment. Emissions from S(2+) ions are generated in a source region with electron temperatures in the range 32,000-56,000 K; S(3+) ion emissions are excited by electrons that average 20,000-40,000 K hotter. This distinct difference suggests that the S(3+) emission source region is spatially separate from the S(2+) source region. Estimated relative aperture filling factors suggest that the S(3+) emissions originate from a region more extended out of the centrifugal plane than the S(2+) emissions.

  20. The large-scale energetic ion layer in the high latitude Jovian magnetosphere as revealed by ULYSSES/HI-SCALE cross-field intensity-gradient measurements

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Karanikola, I.; Marhavilas, P. K.; Sarris, E. T.

    2012-08-01

    ULYSSES investigated the high latitude Jovian magnetosphere for a second time, after Pioneer 11 mission, and gave us the opportunity to search the structure and the dynamics of this giant magnetosphere above the magnetodisc. Kivelson and Williams (1976) and Kennel and Coroniti (1979) reported that Pioneer 11 observed energetic particle intensities at high latitudes at the same level with those measured in the plasma sheet and inferred that they were not consistent with the magnetodisc model. ULYSSES observations supported the idea about a large-scale layer of energetic ions and electrons in the outer high latitude Jovian magnetosphere (Cowley et al., 1996; Anagnostopoulos et al., 2001a). This study performs a number of further tests for the existence of the large scale layer of energetic ions in the outer high latitude Jovian magnetosphere by studying appropriate cross-B field anisotropies in order to monitor the ion northward/southward intensity gradients. In particular, we examined ULYSSES/HI-SCALE observations of energetic ions with large gyro-radius (0.5-1.6 MeV protons and>2.5 MeV heavy (Z>5) ions) in order to compare instant intensity changes with remote sensing intensity gradients. Our analysis confirms the existence of an energetic particle layer in the north hemisphere, during the inbound trajectory of ULYSSES traveling at moderate latitudes, and in the south high-latitude duskside magnetosphere, during the outbound segment of the spacecraft trajectory. Our ULYSSES/HI-SCALE data analysis also provides evidence for the detection of an energetic proton magnetopause boundary layer during the outbound trajectory of the spacecraft. During ULYSSES flyby of Jupiter the almost permanent appearance of alternative northward and southward intensity gradients suggests that the high latitude layer appeared to be a third major area of energetic particles, which coexisted with the radiation belts and the magnetodisc.

  1. Magnetohydrodynamic Simulations of the Effects of the Solar Wind on the Jovian Magnetosphere

    NASA Technical Reports Server (NTRS)

    Walker, Raymond J.; Ogino, Tatsuki; Kivelson, Margaret G.

    2001-01-01

    We have used a three-dimensional magnetohydrodynamic simulation of the interaction between the solar wind and a rapidly rotating magnetosphere to study the effects of the solar wind dynamic pressure and the interplanetary magnetic field IMF on the configuration of the Jovian magnetosphere. Both the solar wind dynamic pressure and the IMF can cause substantial changes in the magnetosphere. On the dayside when the pressure increases the bow shock and magnetopause move toward Jupiter and the equatorial magnetic field in the middle magnetosphere becomes more dipole-like. When the pressure decreases the boundaries move farther from Jupiter and the dayside magnetic field becomes stretched out into a more tail-like configuration. For northward IMF the boundaries move toward Jupiter but the field becomes more tail-like. Finally, for southward IMF the boundaries move away and the field becomes more dipole-like. These changes are qualitatively consistent with those observed on spacecraft passing through the dayside magnetosphere. However, we were not always able to get quantitative agreement. In particular the model does not reproduce the extremely tail-like magnetic field observed during the Pioneer 10 and Ulysses inbound passes. The solar wind and IMF also influence the configuration of the middle magnetosphere in the magnetotail. Tailward flows were found in the nightside equatorial plasma sheet for most IMF orientations. Both inertial effects and the IMF influence reconnection in the tail. The only time the tailward flow in the magnetotail stopped was during prolonged intervals with southward IMF. Then reconnection in the polar cusp caused the flow to move out of the equatorial plane.

  2. Excitation of Jovian seismic waves by the Shoemaker-Levy 9 cometary impact

    NASA Astrophysics Data System (ADS)

    Lognonne, P.; Mosser, B.; Dahlen, F. A.

    1994-08-01

    The kinetic energy released by the collision of the comet Shoemaker-Levy 9 with Jupiter is expected to be between 1020 J and 1023 J. This energy will excite seismic waves, which will propagate within Jupiter. These seismic waves are computed by summing normal modes of degree l up to 1400 and frequency nu up to 10 mHz. The excitation amplitudes are obtained using a model of the blast wave induced by the explosion of the comet. Keeping in mind the possible detection of the waves with an IR camera, we examine the thermal signature of the global modes and transient waves excited by the impact. We show that the excitation of surface waves and normal modes will produce a directly observable signal for strong impacts only. An impact with an energy greater than 2.8 x 1021 J will produce a 10-mHz frequency P wave with associated peak-to-peak temperature fluctuations greater than 0.01 K at the antipode. Surface waves with frequencies less than 3 mHz will give rise to fluctuations everywhere in excess of 0.01 K for impacts greater than 9 x 1022 J. Lower energy impacts will not be directly detectable, the signal-to-noise ratio on a single pixel of the camera being too low. Stacking methods might enable the detection of P waves generated by impacts with energies as low as 7.25 x 1020 J at Delta = 90 deg and of surface waves generated by impacts as low as 1.4 x 1021 J. High-frequency monitoring of the temperature in the jovian troposphere during at least 2 hr after each impact, and low-frequency monitoring during the remaining observation time may provide unique information on the inner structure of Jupiter, including the core and the discontinuity due to the possible plasma phase transition of hydrogen.

  3. Polarization and direction of arrival of Jovian quasiperiodic bursts observed by Cassini

    NASA Astrophysics Data System (ADS)

    Kimura, T.; Cecconi, B.; Zarka, P.; Kasaba, Y.; Tsuchiya, F.; Misawa, H.; Morioka, A.

    2012-11-01

    Jovian quasiperiodic (QP) radio bursts are suspected to be associated with relativistic particle accelerations occurring with a quasiperiodicity between a few minutes and a few tens of minutes in Jupiter's polar magnetosphere. Understanding the excitation and propagation of QP bursts could help us to better understand this periodic energization process. A first necessary step is to measure the wave mode, source location, and directivity of QP bursts. For that purpose, we performed a statistical analysis of goniopolarimetric measurements of QP bursts made with the Radio and Plasma Wave Science investigation (RPWS) onboard Cassini spacecraft during the Jupiter flyby of 2000-2001. We studied two groups of QP bursts on 22 and 23 December 2000, and we found consistent source directions about 50 RJ north of Jupiter with an error bar ?20 RJ. Statistics of the Stokes parameters indicate that QP bursts are partially left-handed polarized (V > 0, Q, U < 0). Together with the direction finding results, these polarization statistics imply that QP bursts observed from low latitudes are L-O mode waves which have been excited in the northern polar source, have propagated toward high latitudes, and then got refracted equatorward in the magnetosheath. Dependence of the Stokes parameters on the longitude indicates that QP bursts are excited within a particular phase range of the planetary rotation, when the system III longitude of the sub-solar point is between 260° and 480°. This implies that QP radio bursts and associated particle accelerations always occur within the same rotational sector, suggesting the existence of a recurrent magnetospheric disturbance at the planetary rotation period. Finally, we propose a possible scenario for the generation and propagation of QP bursts by combining the results of the present study with those of other recent observational and theoretical studies.

  4. Ducks on the torus: existence and uniqueness

    E-print Network

    Schurov, Ilya

    2009-01-01

    We show that there exist generic slow-fast systems with only one (time-scaling) parameter on the two-torus, which have canard cycles for arbitrary small values of this parameter. This is in drastic contrast with the planar case, where canards usually occur in two-parametric families. Here we treat systems with a convex slow curve. In this case there is a set of parameter values accumulating to zero for which the system has exactly one attracting and one repelling canard cycle. The basin of the attracting cycle is almost the whole torus.

  5. Cassini detection of water-group pick-up ions in the Enceladus torus R. L. Tokar,1

    E-print Network

    Johnson, Robert E.

    Cassini detection of water-group pick-up ions in the Enceladus torus R. L. Tokar,1 R. J. Wilson,1 R 2008; published 24 July 2008. [1] This study reports direct detection by the Cassini plasma corotating with Saturn. They are identified in the Cassini data via their characteristic ring-like signatures

  6. The national spherical torus experiment (NSTX) research programme and progress towards high beta, long pulse operating scenarios

    Microsoft Academic Search

    E. J. Synakowski; M. G. Bell; R. E. Bell; T. Bigelow; M. Bitter; W. Blanchard; J. Boedo; C. Bourdelle; C. Bush; D. S. Darrow; E. D. Fredrickson; D. A. Gates; M. Gilmore; L. R. Grisham; J. C. Hosea; D. W. Johnson; R. Kaita; S. M. Kaye; S. Kubota; H. W. Kugel; B. P. LeBlanc; K. Lee; R. Maingi; J. Manickam; R. Maqueda; E. Mazzucato; S. S. Medley; J. Menard; D. Mueller; B. A. Nelson; C. Neumeyer; M. Ono; F. Paoletti; H. K. Park; S. F. Paul; Y.-K. M. Peng; C. K. Phillips; S. Ramakrishnan; R. Raman; A. L. Roquemore; A. Rosenberg; P. M. Ryan; S. A. Sabbagh; C. H. Skinner; V. Soukhanovskii; T. Stevenson; D. Stutman; D. W. Swain; G. Taylor; A. Von Halle; J. Wilgen; M. Williams; J. R. Wilson; S. J. Zweben; R. Akers; R. E. Barry; P. Beiersdorfer; J. M. Bialek; B. Blagojevic; P. T. Bonoli; R. Budny; M. D. Carter; C. S. Chang; J. Chrzanowski; W. Davis; B. Deng; E. J. Doyle; L. Dudek; J. Egedal; R. Ellis; J. R. Ferron; M. Finkenthal; J. Foley; E. Fredd; A. Glasser; T. Gibney; R. J. Goldston; R. Harvey; R. E. Hatcher; R. J. Hawryluk; W. Heidbrink; K. W. Hill; W. Houlberg; T. R. Jarboe; S. C. Jardin; H. Ji; M. Kalish; J. Lawrance; L. L. Lao; K. C. Lee; F. M. Levinton; N. C. Luhmann; R. Majeski; R. Marsala; D. Mastravito; T. K. Mau; B. McCormack; M. M. Menon; O. Mitarai; M. Nagata; N. Nishino; M. Okabayashi; G. Oliaro; D. Pacella; R. Parsells; T. Peebles; B. Peneflor; D. Piglowski; R. Pinsker; G. D. Porter; A. K. Ram; M. Redi; M. Rensink; G. Rewoldt; J. Robinson; P. Roney; M. Schaffer; K. Shaing; S. Shiraiwa; P. Sichta; D. Stotler; B. C. Stratton; Y. Takase; X. Tang; R. Vero; W. R. Wampler; G. A. Wurden; X. Q. Xu; J. G. Yang; L. Zeng; W. Zhu

    2003-01-01

    A major research goal of the national spherical torus experiment is establishing long-pulse, high beta, high confinement operation and its physics basis. This research has been enabled by facility capabilities developed during 2001 and 2002, including neutral beam (up to 7 MW) and high harmonic fast wave (HHFW) heating (up to 6 MW), toroidal fields up to 6 kG, plasma

  7. Progress in the studies of passive heat removal in the next European torus under accident conditions

    Microsoft Academic Search

    A. Soria; V. Renda; L. Papa; F. Fenoglio

    1989-01-01

    Within the framework of safety analysis for the next European torus, a decay heat hazards assessment is under way in Ispra. Undercooling accidents (loss-of-coolant and loss-of-flow accidents (LOCAs and LOFAs)) due to pump failure have been investigated assuming an automatic plasma shutdown in both cases. The passive heat removal mechanisms considered include radiation between components and residual cooling by the

  8. Spreading of Saturn's Neutral Torus

    NASA Astrophysics Data System (ADS)

    Cassidy, T. A.; Johnson, R. E.; Kuo, C.

    2009-12-01

    The H2O vapor ejected from Enceladus' south pole forms a Saturn-encircling cloud of neutrals and plasma. Two decades of OH cloud modeling and observations suggested that H2O, and its dissociation and ionization products are spread throughout the Saturnian system primarily by magnetospheric plasma/neutral interactions (e.g., Johnson et al., APJ, 2006). In recent years, Cassini UVIS data has shown even broader O and H clouds that are not reproduced by previous models. Using a Direct Simulation Monte Carlo model of the neutral cloud we have found that the neutral-neutral collisions are key to explaining the unexpected breadth of the O cloud (See also: Farmer, Icarus, 2009). We will also discuss the cloud's curious H2O maser emission (Pogrebenko et al., 2009), which, we hypothesize, is a consequence of electron impact excitation.

  9. Simultaneous Analysis of Recurrent Jovian Electron Increases and Galactic Cosmic Ray Decreases

    E-print Network

    Kühl, P; Dunzlaff, P; Fichtner, H; Gieseler, J; Gómez-Herrero, R; Heber, B; Klassen, A; Kleimann, J; Kopp, A; Potgieter, M; Scherer, K; Strauss, R D

    2013-01-01

    The transport environment for particles in the heliosphere, e.g. galactic cosmic rays (GCRs) and MeV electrons (including those originating from Jupiters magnetosphere), is defined by the solar wind flow and the structure of the embedded heliospheric magnetic field. Solar wind structures, such as co-rotating interaction regions (CIR), can result in periodically modulation of both particles species. A detailed analysis of this recurrent Jovian electron events and galactic cosmic ray decreases measured by SOHO EPHIN is presented here, showing clearly a change of phase between both phenomena during the cause of the years 2007 and 2008. This effect can be explained by the change of difference in heliolongitude between the Earth and Jupiter, which is of central importance for the propagation of Jovian electrons. Furthermore, the data can be ordered such that the 27-day Jovian electron variation vanishes in the sector which does not connect the Earth with Jupiter magnetically using observed solar wind speeds.

  10. Retrievals of Jovian Tropospheric Phosphine from Cassini/CIRS

    NASA Technical Reports Server (NTRS)

    Irwin, P. G. J.; Parrish, P.; Fouchet, T.; Calcutt, S. B.; Taylor, F. W.; Simon-Miller, A. A.; Nixon, C. A.

    2004-01-01

    On December 30th 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the Jovian atmosphere, rings and satellites from 10-1400 cm(exp -1) (1000-7 microns) at a programmable spectral resolution of 0.5 to 15 cm(exp -1). The improved spectral resolution of CIRS over previous IR instrument-missions to Jupiter, the extended spectral range, and higher signal-to-noise performance provide significant advantages over previous data sets. CIRS global observations of the mid-infrared spectrum of Jupiter at medium resolution (2.5 cm(exp -1)) have been analysed both with a radiance differencing scheme and an optimal estimation retrieval model to retrieve the spatial variation of phosphine and ammonia fractional scale height in the troposphere between 60 deg S and 60 deg N at a spatial resolution of 6 deg. The ammonia fractional scale height appears to be high over the Equatorial Zone (EZ) but low over the North Equatorial Belt (NEB) and South Equatorial Belt (SEB) indicating rapid uplift or strong vertical mixing in the EZ. The abundance of phosphine shows a similar strong latitudinal variation which generally matches that of the ammonia fractional scale height. However while the ammonia fractional scale height distribution is to a first order symmetric in latitude, the phosphine distribution shows a North/South asymmetry at mid latitudes with higher amounts detected at 40 deg N than 40 deg S. In addition the data show that while the ammonia fractional scale height at this spatial resolution appears to be low over the Great Red Spot (GRS), indicating reduced vertical mixing above the approx. 500 mb level, the abundance of phosphine at deeper levels may be enhanced at the northern edge of the GRS indicating upwelling.

  11. ORIGIN OF THE DIFFERENT ARCHITECTURES OF THE JOVIAN AND SATURNIAN SATELLITE SYSTEMS

    SciTech Connect

    Sasaki, T.; Ida, S. [Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Stewart, G. R., E-mail: takanori@geo.titech.ac.j, E-mail: ida@geo.titech.ac.j, E-mail: gstewart@lasp.colorado.ed [Laboratory for Atmospheric and Space Physics, University of Colorado, Campus Box 392, Boulder, CO 80309-0392 (United States)

    2010-05-10

    The Jovian regular satellite system mainly consists of four Galilean satellites that have similar masses and are trapped in mutual mean-motion resonances except for the outer satellite, Callisto. On the other hand, the Saturnian regular satellite system has only one big icy body, Titan, and a population of much smaller icy moons. We have investigated the origin of these major differences between the Jovian and Saturnian satellite systems by semi-analytically simulating the growth and orbital migration of proto-satellites in an accreting proto-satellite disk. We set up two different disk evolution/structure models that correspond to Jovian and Saturnian systems, by building upon previously developed models of an actively supplied proto-satellite disk, the formation of gas giants, and observations of young stars. Our simulations extend previous models by including the (1) different termination timescales of gas infall onto the proto-satellite disk and (2) different evolution of a cavity in the disk, between the Jovian and Saturnian systems. We have performed Monte Carlo simulations and have shown that in the case of the Jovian systems, four to five similar-mass satellites are likely to remain trapped in mean-motion resonances. This orbital configuration is formed by type I migration, temporal stopping of the migration near the disk inner edge, and quick truncation of gas infall caused by Jupiter opening a gap in the solar nebula. The Saturnian systems tend to end up with one dominant body in the outer regions caused by the slower decay of gas infall associated with global depletion of the solar nebula. The total mass and compositional zoning of the predicted Jovian and Saturnian satellite systems are consistent with the observed satellite systems.

  12. Operational Regimes of the National Spherical Torus Experiment

    SciTech Connect

    D. Mueller; M.G. Bell; R.E. Bell; M. Bitter; T. Bigelow; P. Bonoli; M. Carter; J. Ferron; E. Fredrickson; D. Gates; L. Grisham; J.C. Hosea; D. Johnson; R. Kaita; S.M. Kaye; H. Kugel; B.P. LeBlanc; R. Maingi; R. Majeski; R. Maqueda; J. Menard; M. Ono; F. Paoletti; S. Paul; C.K. Phillips; R. Pinsker; R. Raman; S.A. Sabbagh; C.H. Skinner; V.A. Soukhanovskii; D. Stutman; D. Swain; Y. Takase; J. Wilgen; J.R. Wilson; G.A. Wurden; S. Zweben

    2002-06-03

    The National Spherical Torus Experiment (NSTX) is a proof-of-principle experiment designed to study the physics of Spherical Tori (ST), i.e., low-aspect-ratio toroidal plasmas. Important issues for ST research are whether the high-eta stability and reduced transport theoretically predicted for this configuration can be realized experimentally. In NSTX, the commissioning of a digital real-time plasma control system, the provision of flexible heating systems, and the application of wall conditioning techniques were instrumental in achieving routine operation with good confinement. NSTX has produced plasmas with R/a {approx} 0.85 m/0.68 m, A {approx} 1.25, Ip * 1.1 MA, BT = 0.3-0.45 T, k * 2.2, d * 0.5, with auxiliary heating by up to 4 MW of High Harmonic Fast Waves, and 5 MW of 80 keV D0 Neutral Beam Injection (NBI). The energy confinement time in plasmas heated by NBI has exceeded 100 ms and a toroidal beta (bT = 2m0

    /BT02, where BT0 is the central vacuum toroidal magnetic field) up to 22% has be en achieved. HHFW power of 2.3 MW has increased the electron temperature from an initial 0.4 keV to 0.9 keV both with and without producing a significant density rise in the plasma. The early application of both NBI and HHFW heating has slowed the penetration of the inductively produced plasma current, modifying the current profile and, thereby, the observed MHD stability.

  13. The interaction of Io's Alfven waves with the Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Wright, A. N.

    1987-09-01

    A numerical solution for the propagation of the Alfven waves produced by Io is presented. The waves are shown to interact strongly with the torus and magnetic-field inhomogeneities. Substantial reflection occurs from the magnetospheric medium, and only about a quarter of the wave power will reach the ionosphere on its first pass. It is concluded that both WKB and ray-tracing arguments are inappropriate, contrary to previous studies. A more realistic picture may be that of a whole field line or L shell resonating in an eigenmode. The Alfven structure behind Io and some possible features that it may exhibit are discussed. In particular, it may be possible to produce decametric arcs that are more closely spaced than ray tracing permits by exciting higher-harmonic eigenmodes of Io's L shell.

  14. Jovian electron propagation close to the sun /at about 0.5 AU/

    NASA Technical Reports Server (NTRS)

    Eraker, J. H.; Simpson, J. A.

    1979-01-01

    On the basis of interplanetary electron flux measurements in the energy range 0.7-25 MeV made on the Mariner 10 spacecraft launched in 1973 for successive encounters with planet Mercury (R approximately equal 0.5 AU), it is shown that the dominant interplanetary flux of electrons close to the sun is Jovian in origin (except for times of solar flares) and that these observations are consistent with a three-dimensional diffusion-convection model which describes Jovian electron propagation in the outer solar system.

  15. The ~10 hour modulation of the relativistic electron spectrum as a result of the periodic motion of the Jovian outer magnetosphere layer: Ulysses observations

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Karanikola, I.; Marhavilas, P. K.

    2013-08-01

    We analyze relativistic (E>3 MeV) electron observations during the dayside inbound trajectory of Ulysses (day 33 to day 38, 1992) in the Jovian magnetosphere and we demonstrate that the continuous presence of a relativistic electron layer at higher north latitudes (Ulysses reached ~40° lat. during closest approach the planet). In particular, we evaluated the cross-B field anisotropy of relativistic (E>3 MeV) electrons intensity by the COSPIN/HET detector onboard Ulysses, and we found that between the times of plasma sheet crossings/approaches, when Ulysses was found far from the magnetodisc, at higher north latitudes, local increases in the relativistic electron intensity and intensity gradient in the northward direction were persistently observed. We also found that (1) the well known ~10 h separated relativistic electron spectral index peaks (spectral softening) and (2) the detection of relativistic electron intensity gradient in the northward direction are related phenomena. We infer that phenomenon 1 and 2 are explained by the ~10 h periodic upward-downward motion of the Jovian magnetosphere, and consequently of the outer magnetosphere relativistic electron layer. ?he above results extends earlier results for low energy electrons and energetic protons (Anagnostopoulos et al., 1998, 2001b) to relativistic electron phenomena, and provide strong evidence, for the first time, that the well known ~10 h rocking of the relativistic electron spectrum in the outer magnetosphere (the so called "clock phenomenon") is a spatial and not a temporal effect, as was earlier hypothesized (Simpson et al.,1992).

  16. Review Closeout for the National Spherical Torus

    E-print Network

    Princeton Plasma Physics Laboratory

    OFFICE OF SCIENCE Review Closeout for the National Spherical Torus Experiment (NSTX) Upgrade Chao, DOE/SC, Chairperson Review Committee Arnie Kellman, General Atomics Will Oren, TJNAF Observers remains the same since the last review. Has the project responded satisfactorily to the recommendations

  17. Space Propulsion via Spherical Torus Fusion Reactor

    Microsoft Academic Search

    Craig H. Williams; Albert J. Juhasz; Stanley K. Borowski; Leonard A. Dudzinski

    2003-01-01

    A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 204 days, with an initial mass in low Earth orbit of 1630 mt. Engineering conceptual design, analysis, and assessment were

  18. Source location of Jupiter's decametric radiation and UV aurora

    NASA Technical Reports Server (NTRS)

    Maeda, Koitiro; Carr, Thomas D.

    1989-01-01

    The source region of a component of Jovian Io-unrelated decametric radiation is inferred geometrically based on simultaneous observations from Voyager spacecraft and a ground-based observatory with the aid of a hollow cone beam model and model of the Jovian magnetic field. The results indicate that the sources of this component lie above the northern hemisphere, and on field lines that connect the Io plasma torus and the Jovian ionosphere in the so-called active sector. It is concluded that an interaction between the Io-torus plasma and the ionospheric plasma through a thin flux tube initiates the decametric radiation.

  19. Reversed-field pinch studies in the Madison Symmetric Torus

    SciTech Connect

    Hokin, S.; Almagri, A.; Cekic, M.; Chapman, B.; Crocker, N.; Den Hartog, D.J.; Fiksel, G.; Henry, J.; Ji, H.; Prager, S.; Sarff, J.; Scime, E.; Shen, W.; Stoneking, M.; Watts, C.

    1993-04-03

    Studies of large-size (R = 1.5 m, a = 0.5 m), moderate current (I < 750 kA) reversed-field pinch (RFP) plasmas are carried out in the Madison Symmetric Torus in order to evaluate and improve RFP confinement, study general toroidal plasma MHD issues, determine the mechanism of the RFP dynamo, and measure fluctuation-induced transport and anomalous ion heating. MST confinement has been improved by reduction of magnetic field errors with correction coils in the primary circuit and reduction of impurities using boronization; high densities have been achieved with hydrogen pellet injection. MHD tearing modes with poloidal mode number m = 1 and toroidal mode numbers n = 5--7 are prevalent and nonlinearly couple to produce sudden relaxations akin to tokamak sawteeth. Edge fluctuation-induced transport has been measured with a variety of insertable probes. Ions exhibit anomalous heating, with increases of ion temperature occuring during strong MHD relaxation. The RFP dynamo has been studied with attention to various possible mechanisms, including motion-EMF drive, the Hall effect, and superthermal electrons. Initial profile control experiments have begun using insertable biased probes and plasma guns. The toroidal field capacity of MST will be upgraded during Summer, 1993 to allow low-current tokamak operation as well as improved RFP operation.

  20. Field and Plasma Science with the Jupiter Icy Moons Orbiter (JIMO)

    Microsoft Academic Search

    K. K. Khurana; W. S. Kurth; J. F. Cooper; J. H. Waite; J. E. Connerney; J. L. Green; F. Crary; W. R. Paterson; R. E. Johnson; C. Paranicas; B. H. Mauk

    2003-01-01

    The field and plasma investigations from JIMO would address fundamental science objectives related to chemistry, internal structure and evolution of Jupiter's Galilean icy satellites. In addition, data collected during the cruise phases of the mission would identify azimuthal asymmetries in the structure and dynamics of the Jovian magnetosphere. The Priority 1 objectives identified by the field and plasma subgroup assisting

  1. Electromagnetic waves in space plasma: Generation and propagation

    Microsoft Academic Search

    V. V. Zhelezniakov

    1977-01-01

    The aim of the book is to provide insight into the mechanisms of electromagnetic wave emission from space plasmas (interstellar medium, supernova remnants, magnetospheres of neutron stars, the solar corona, Jovian ionosphere, etc.), which is essential for interpreting the results of radio astronomic investigations. An attempt is made to outline systematically the general principles of wave generation and propagation in

  2. Quasi-periodic electron bursts in the Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Steffl, A. J.; Shinn, A. B.

    2012-12-01

    In early 2007, the New Horizons spacecraft flew through the Jovian magnetosphere on the dusk side. During the flyby, the Alice FUV spectrograph proved that in addition to detecting FUV photons, it was also quite effective at detecting MeV electrons, which can penetrate the relatively thin instrument housing and interact with the microchannel plate detector. Radiation modeling shows that Alice is sensitive primarily to electrons with energies between 1-8 MeV. Alice cannot determine the spatial distribution of these MeV electrons, nor does it have any energy resolution, but it does have large count rates (up to 15000 counts/s) and a time resolution of 1s—the highest of any electron detector yet flown to Jupiter. Along New Horizons' trajectory from 60 R_J upstream of Jupiter to closest approach at 32 R_J on the dusk side to 60 R_J downstream of Jupiter, we find the flux of MeV electrons to be highly variable on timescales of minutes to hours. There are numerous factor of two changes in electron flux (both increases and decreases) that occur over 50-100s. Frequently, though not always, the MeV electron flux exhibits quasi-periodic variations with timescales of 1-3 minutes. The amplitude of these bursts can vary, sometimes abruptly, from a few percent to factors of several. We also see evidence of larger amplitude 20-45 minute QP bursts with smaller amplitude 1-3 minute bursts superimposed. During two incidences of particularly strong 1-3 minute QP bursts, we find the magnetic field lines passing through the spacecraft map back to Jupiter's ionosphere just inside the main auroral oval to the same location where 1-3 minute QP flares have been seen in the FUV aurora. We therefore suggest that these auroral flares are not caused by pulsed reconnection at the dayside magnetopause, as has been proposed, but rather by some acceleration mechanism internal to the magnetosphere.

  3. Quasi-Periodic Electron Bursts in the Jovian Magnetosphere

    NASA Astrophysics Data System (ADS)

    Steffl, Andrew J.; Shinn, A. B.

    2013-10-01

    In early 2007, the New Horizons spacecraft flew through the Jovian magnetosphere on the dusk side. During the flyby, the Alice FUV spectrograph proved that in addition to detecting FUV photons, it was also quite effective at detecting MeV electrons, which can penetrate the relatively thin instrument housing and interact with the microchannel plate detector. Radiation modeling shows that Alice is sensitive primarily to electrons with energies between 1-8 MeV. Alice cannot determine the spatial distribution of these MeV electrons, nor does it have any energy resolution, but it does have large count rates (up to 15000 counts/s) and a time resolution of 1s--among the highest of any electron detector flown to Jupiter. Along New Horizons’ trajectory from 60 R_J upstream of Jupiter to closest approach at 32 R_J on the dusk side to 60 R_J downstream of Jupiter, we find the flux of MeV electrons to be highly variable on timescales of minutes to hours. There are numerous factor of two changes in electron flux (both increases and decreases) that occur over 50-100s. Frequently, though not always, the MeV electron flux exhibits quasi-periodic variations with timescales of 1-3 minutes. The amplitude of these bursts can vary, sometimes abruptly, from a few percent to factors of several. We also see evidence of larger amplitude 20-45 minute QP bursts with smaller amplitude 1-3 minute bursts superimposed. During two incidences of particularly strong 1-3 minute QP bursts, we find the magnetic field lines passing through the spacecraft map back to Jupiter’s ionosphere just inside the main auroral oval to the same location where 1-3 minute QP flares have been seen in the FUV aurora. We therefore suggest that these auroral flares are not caused by magnetic reconnection at the dayside magnetopause, but rather by some acceleration mechanism internal to the magnetosphere.

  4. Jovian Karmen vortex streets as attractors in turbulent zonal flow

    NASA Astrophysics Data System (ADS)

    Humphreys, Tom Daniel, III

    2000-11-01

    Other than the Great Red Spot, almost all long-lived vortices in the weather layer on Jupiter exist multiply at their latitudes in staggered rows of cyclones and anti-cyclones called Kármán vortex streets. Examples include the White Ovals and the small anti- cyclones at 40°S. We model these vortex streets with computational solutions of the 1½ layer quasigeostrophic (QG) equations with finite Rossby deformation radius. Using a contour dynamics (CD) method, we find all possible steady state vortex streets, and classify them according to the three possible configurations of their streamlines and stagnation points. Over wide ranges of parameter space, the steady states are stable to linear and finite-amplitude perturbations. Because the QG equations conserve energy and momentum, and because potential vorticity is advectively conserved, any initial condition maintains over time its original values of energy, momentum, potential circulation and enstrophy, etc. With such a Hamiltonian method, one would need to be improbably lucky with one's initial conditions to accurately match the conserved quantities of the vortex streets on Jupiter. A more realistic model should include two effects of turbulence: merger of small vortices and the filamentation from large vortices. We model these effects in the solution of the QG equations on a two-dimensional grid with weak forcing and dissipation. The previously large and undifferentiated parameter space develops a small, robust attractor and large basins of attraction. The location of the attractor, i.e., the values of its ``conserved quantities'', depends only on the level of forcing and not on the initial conditions. We then use an analogous forced and dissipated CD model with contour surgery to duplicate these results. The CD model is much easier to interpret, and we use it to develop a simple physical explanation of where and why the attractor forms. Essentially, one type of steady state, which occupies zero area in parameter space, is an attractor for the other two types when they are forced and dissipated. The presence of this attractor has important implications for models of the Jovian weather layer, because it significantly restricts the number of independent parameter values.

  5. Acceleration of galactic and Jovian electrons at the heliospheric solar wind termination shock

    Microsoft Academic Search

    L. J. Haasbroek; M. S. Potgieter; J. A. Le Roux

    1997-01-01

    In 1973, with the aid of the Pioneer 10 spacecraft, it was discovered that the Jovian (Jupiter) magnetosphere at 5 AU is a relatively strong source of electrons with energies up to even ?100 MeV. The most recent direct observational confirmation was in 1992 with the Ulysses spacecraft. These particles can be detected at Earth (1 AU) and may be

  6. Acceleration of galactic and Jovian electrons at the heliospheric solar wind termination shock

    Microsoft Academic Search

    L. J. Haasbroek; M. S. Potgieter; J. A. Le Roux

    1997-01-01

    In 1973, with the aid of the Pioneer 10 spacecraft, it was discovered that the Jovian (Jupiter) magnetosphere at 5 AU is a relatively strong source of electrons with energies up to even ~ 100 MeV. The most recent direct observational confirmation was in 1992 with the Ulysses spacecraft. These particles can be detected at Earth (1 AU) and may

  7. Ultraviolet-Photoproduced Organic Solids Synthesized Under Simulated Jovian Conditions: Molecular Analysis

    Microsoft Academic Search

    B. N. Khare; Carl Sagan; Eric L. Bandurski; Bartholomew Nagy

    1978-01-01

    In an earlier paper, Khare and Sagan reported the production of a brownish polymeric material from the near-ultraviolet irradiation of simulated jovian atmospheres with a low hydrogen abundance. Examination of this product indicates that hydrogen sulfide is the initial photon acceptor; the powder resulting after extraction with benzene is 84 percent sulfur, largely S8. In results reported here, the remaining

  8. Detailed study of FUV Jovian auroral features with the post-COSTAR HST faint object camera

    Microsoft Academic Search

    Renée Prangé; Daniel Rego; Laurent Pallier; Jack Connerney; Philippe Zarka; Julien Queinnec

    1998-01-01

    A set of Hubble Space Telescope faint object camera images taken in the H2 bands near 1550 Å is used to infer the morphological properties of the steady state Jovian FUV aurorae. We focus on issues best addressed using the excellent spatial resolution available after correction of the spherical aberration, i.e., those related to high latitude or small auroral features.

  9. Operations cost Reduction for a Jovian Science Mission Using CubeSats

    NASA Astrophysics Data System (ADS)

    Rajguru, A.; Faler, A. C.

    2014-06-01

    This paper proposes the operation of a mission architecture for jovian satellite tour, that uses small orbiter 6U CubeSats, airless body landers of the same order of 6U size and a mothership carrier that will act as a communication hub to DSN.

  10. Neutral wind control of the Jovian magnetosphere-ionosphere current system

    Microsoft Academic Search

    Chihiro Tao; Hitoshi Fujiwara; Yasumasa Kasaba

    2009-01-01

    In order to clarify the role of neutral dynamics in the Jovian magnetosphere-ionosphere-thermosphere coupling system, we have developed a new numerical model that includes the effect of neutral dynamics on the coupling current. The model calculates axisymmetric thermospheric dynamics and ion composition by considering fundamental physical and chemical processes. The ionospheric Pedersen current is obtained from the thermospheric and ionospheric

  11. SPECTROSCOPIC SEARCH FOR WATER ICE ON JOVIAN TROJAN ASTEROIDS Bin Yang and David Jewitt

    E-print Network

    Jewitt, David C.

    SPECTROSCOPIC SEARCH FOR WATER ICE ON JOVIAN TROJAN ASTEROIDS Bin Yang and David Jewitt Institute and so may contain considerable amounts of water ice. We seek near-infrared spectroscopic evidence for the 1.5 and 2.0 m water ice bands in the Trojans. Our sample is focused on objects identified

  12. Exploration of High Harmonic Fast Wave Heating on the National Spherical Torus Experiment

    SciTech Connect

    J.R. Wilson; R.E. Bell; S. Bernabei; M. Bitter; P. Bonoli; D. Gates; J. Hosea; B. LeBlanc; T.K. Mau; S. Medley; J. Menard; D. Mueller; M. Ono; C.K. Phillips; R.I. Pinsker; R. Raman; A. Rosenberg; P. Ryan; S. Sabbagh; D. Stutman; D. Swain; Y. Takase; J. Wilgen; the NSTX Team

    2003-02-11

    High Harmonic Fast Wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high-beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [Ono, M., Kaye, S.M., Neumeyer, S., et al., Proceedings, 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999, (IEEE, Piscataway, NJ (1999), p. 53.)] is such a device. An radio-frequency (rf) heating system has been installed on NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode (high-confinement mode) discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.

  13. Advanced tokamak reactors based on the spherical torus (ATR/ST). Preliminary design considerations

    SciTech Connect

    Miller, R.L.; Krakowski, R.A.; Bathke, C.G.; Copenhaver, C.; Schnurr, N.M.; Engelhardt, A.G.; Seed, T.J.; Zubrin, R.M.

    1986-06-01

    Preliminary design results relating to an advanced magnetic fusion reactor concept based on the high-beta, low-aspect-ratio, spherical-torus tokamak are summarized. The concept includes resistive (demountable) toroidal-field coils, magnetic-divertor impurity control, oscillating-field current drive, and a flowing liquid-metal breeding blanket. Results of parametric tradeoff studies, plasma engineering modeling, fusion-power-core mechanical design, neutronics analyses, and blanket thermalhydraulics studies are described. The approach, models, and interim results described here provide a basis for a more detailed design. Key issues quantified for the spherical-torus reactor center on the need for an efficient drive for this high-current (approx.40 MA) device as well as the economic desirability to increase the net electrical power from the nominal 500-MWe(net) value adopted for the baseline system. Although a direct extension of present tokamak scaling, the stablity and transport of this high-beta (approx.0.3) plasma is a key unknown that is resoluble only by experiment. The spherical torus generally provides a route to improved tokamak reactors as measured by considerably simplified coil technology in a configuration that allows a realistic magnetic divertor design, both leading to increased mass power density and reduced cost.

  14. plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, H. Y.; Jin, C. G.; Yang, Y.; Ye, C.; Zhuge, L. J.; Wu, X. M.

    2014-12-01

    As-deposited HfO2 films were modified by CHF3, C4F8, and mixed C4F8/O2 plasmas in a dual-frequency capacitively coupled plasma chamber driven by radio frequency generators of 60 MHz as the high frequency (HF) source and 2 MHz as the low frequency source (60/2 MHz). The influences of various surface plasma treatments under CHF3, C4F8, and C4F8/O2 were investigated in order to understand the chemical and structural changes in thin-film systems, as well as their influence on the electrical properties. Fluorine atoms were incorporated into the HfO2 films by either CHF3 or C4F8 plasma treatment; meanwhile, the C/F films were formed on the surface of the HfO2 films. The formation of C/F layers decreased the k value of the gate stacks because of its low dielectric constant. However, the addition of O2 gas in the discharge gases suppressed the formation of C/F layers. After thermal annealing, tetragonal HfO2 phase was investigated in both samples treated with CHF3 and C4F8 plasmas. However, the samples treated with O-rich plasmas showed monoclinic phase, which indicated that the addition of O plasmas could influence the Hf/O ratio of the HfO2 films. The mechanism of the t-HfO2 formation was attributed to oxygen insufficiency generated by the incorporation of F atoms. The capacitors treated with C4F8/O2 plasmas displayed the highest k value, which ascribed that the C/F layers were suppressed and the tetragonal phase of HfO2 was formed. Good electrical properties, especially on the hysteresis voltage and frequency dispersion, were obtained because the bulk traps were passivated by the incorporation of F atoms. However, the H-related traps were generated during the CHF3 plasma treatments, which caused the performance degradation. All the treated samples showed lower leakage current density than the as-deposited HfO2 films at negative bias due to the reduced trap-assisted tunneling by the incorporation of F to block the electrons transferring from metal electrode to the trap level.

  15. TORUS: Radiation transport and hydrodynamics code

    NASA Astrophysics Data System (ADS)

    Harries, Tim

    2014-04-01

    TORUS is a flexible radiation transfer and radiation-hydrodynamics code. The code has a basic infrastructure that includes the AMR mesh scheme that is used by several physics modules including atomic line transfer in a moving medium, molecular line transfer, photoionization, radiation hydrodynamics and radiative equilibrium. TORUS is useful for a variety of problems, including magnetospheric accretion onto T Tauri stars, spiral nebulae around Wolf-Rayet stars, discs around Herbig AeBe stars, structured winds of O supergiants and Raman-scattered line formation in symbiotic binaries, and dust emission and molecular line formation in star forming clusters. The code is written in Fortran 2003 and is compiled using a standard Gnu makefile. The code is parallelized using both MPI and OMP, and can use these parallel sections either separately or in a hybrid mode.

  16. Is Jupiter's ionosphere a significant plasma source for its magnetosphere?

    NASA Astrophysics Data System (ADS)

    Nagy, A. F.; Barakat, A. R.; Schunk, R. W.

    1986-01-01

    A semikinetic model was used to study the steady state, collisionless, polar wind outflow from the Jovian polar caps. H+ escape fluxes and energies were calculated for a range of conditions, including several values of the ambient electron temperature, different hot electron populations, and both with and without the effects of the centrifugal force. The calculations indicate that if hot electron populations exist over the Jovian polar caps, as they do on earth, polar wind escape fluxes of the order of 108cm-2s-1 are possible. When integrated over the polar cap area, escape fluxes of this order of magnitude imply an ionospheric source strength of 2×1028ions/s, which is comparable to the present estimate of the total magnetospheric plasma source population. Therefore, the ionosphere may play an important role in populating the Jovian magnetosphere, specifically the "hidden", low energy, light ion component of the population.

  17. Is Jupiter's ionosphere a significant plasma source for its magnetosphere?

    NASA Technical Reports Server (NTRS)

    Nagy, A. F.; Barakat, A. R.; Schunk, R. W.

    1986-01-01

    A semikinetic model was used to study the steady state, collisionless, polar wind outflow from the Jovian polar caps. H(+)-escape fluxes and energies were calculated for a range of conditions, including several values of the ambient electron temperature, different hot electron populations, and both with and without the effects of the centrifugal force. The calculations indicate that if hot electron populations exist over the Jovian polar caps, as they do on earth, polar wind escape fluxes of the order of 10 to the 8th per sq cm s are possible. When integrated over the polar cap area, escape fluxes of this order of magnitude imply an ionospheric source strength of 2 x 10 to the 28th ions/s, which is comparable to the present estimate of the total magnetospheric plasma source population. Therefore, the ionosphere may play an important role in populating the Jovian magnetosphere, specifically the hidden, low energy, light ion component of the population.

  18. Technological issues of ion cyclotron heating of fusion plasmas

    Microsoft Academic Search

    D. Q. Hwang; C. M. Fortgang

    1985-01-01

    With the recent promising results of plasma heating using electromagnetic waves (EM waves) in the ion cyclotron range of frequency (ICRF) on the Princeton Large Torus (PLT) tokamak the feasibility of employing ICRF heating to a reactor-like magnetic confinement device is increasing. The high power ICRF experiments funded on JET (Joint European Torus in England) and JT-60 (in Japan) will

  19. Acoustic diffraction by a thin soft torus

    Microsoft Academic Search

    Ivan I. Argatov; Federico J. Sabina

    2008-01-01

    The scattering problem of an incident plane sound wave with a fixed wave number by a thin soft-sound torus with arbitrary shaped cross-section is considered. The method of matched asymptotic expansions is used to construct a formal asymptotic solution of the problem. The asymptotic model, which is described by a well-posed integral equation, is constructed with the help of a

  20. Numerical study of the Columbia high-beta device: Torus-II

    SciTech Connect

    Izzo, R.

    1981-01-01

    The ionization, heating and subsequent long-time-scale behavior of the helium plasma in the Columbia fusion device, Torus-II, is studied. The purpose of this work is to perform numerical simulations while maintaining a high level of interaction with experimentalists. The device is operated as a toroidal z-pinch to prepare the gas for heating. This ionization of helium is studied using a zero-dimensional, two-fluid code. It is essentially an energy balance calculation that follows the development of the various charge states of the helium and any impurities (primarily silicon and oxygen) that are present. The code is an atomic physics model of Torus-II. In addition to ionization, we include three-body and radiative recombination processes.

  1. Design of the new magnetic sensors for Joint European Torus

    SciTech Connect

    Coccorese, V.; Albanese, R.; Altmann, H.; Cramp, S.; Edlington, T.; Fullard, K.; Gerasimov, S.; Huntley, S.; Lam, N.; Loving, A.; Riccardo, V.; Sartori, F.; Marren, C.; McCarron, E.; Sowden, C.; Tidmarsh, J.; Basso, F.; Cenedese, A.; Chitarin, G.; DegliAgostini, F. [Consorzio CREATE, Associazione EURATOM-ENEA sulla Fusione, Via Claudio 21, I-80125 Naples (Italy); Association EURATOM-UKAEA Fusion, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Corso Stati Uniti 4, I-35127 Padova (Italy); Asociacion EURATOM-CIEMAT para Fusion, Avenida Complutense 22, E-28040 Madrid (Spain)] [and others

    2004-10-01

    A new magnetic diagnostics system has been designed for the 2005 Joint European Torus (JET) experimental campaigns onward. The new system, which adds to the existing sensors, aims to improve the JET safety, reliability, and performance, with respect to: (i) equilibrium reconstruction; (ii) plasma shape control; (iii) coil failures; (iv) VDEs; (v) iron modeling; and (vi) magnetohydrodynamics poloidal mode analysis. The system consists of in-vessel and ex-vessel sensors. The former are a set of 38 coil pairs (normal and tangential), located as near as possible to the plasma. Coils are generally grouped in rails, in order to ease remote handling in-vessel installation. The system includes: (i) two outer poloidal limiter arrays (2x7 coil pairs); (ii) two divertor region arrays (2x7 coil pairs); and (iii) two top coil arrays (2x5 coil pairs). Ex-vessel sensors, including discrete coils, Hall probes, and flux loops (26 in total) will be installed on the iron limbs, in order to provide experimental data for the treatment of iron in equilibrium codes. The design is accompanied by a software analysis, aiming to predict the expected improvement.

  2. Instrumentation for the joint European torus motional Stark effect diagnostic

    NASA Astrophysics Data System (ADS)

    Stratton, B. C.; Long, D.; Palladino, R.; Hawkes, N. C.

    1999-01-01

    A motional Stark effect magnetic field pitch angle diagnostic has been implemented on the joint European torus (JET) tokamak. The instrumentation designed following the study by Hawkes et al. (these proceedings) is described. D? emission from the Octant 4 neutral beams is collected by optics which transport the plasma image outside the vacuum vessel and through a pair of photoelastic modulators (PEMs) and a linear polarizer. The light is fiber-optically coupled to interference filter spectrometers, which incorporate a remotely controlled filter tilting mechanism. This allows the center wavelength of the filter bandpass to be tuned over a range sufficient for observation of the ? and ? lines of the Stark spectrum emitted by the full- and half-energy components of the beam, providing flexibility to make measurements with a variety of beam configurations. The detectors are low-noise avalanche photodiode modules. Fast digital signal processing techniques are used to extract the Fourier components of the signal at the PEM first and second harmonic frequencies. Analysis of these signals will yield the magnetic field pitch angle, which will be used as a constraint on EFIT equilibrium reconstruction modeling to obtain the q(r) profile. The system has 25 spatial channels covering the outer-half of a JET plasma with spatial resolution of 0.03-0.07 m per channel with ˜0.05 m channel-to-channel separation. Time resolution is expected to be 1-10 ms.

  3. Nonlocal neoclassical transport in tokamak and spherical torus experiments

    NASA Astrophysics Data System (ADS)

    Wang, W. X.; Rewoldt, G.; Tang, W. M.; Hinton, F. L.; Manickam, J.; Zakharov, L. E.; White, R. B.; Kaye, S.

    2006-08-01

    Large ion orbits can produce nonlocal neoclassical effects on ion heat transport, the ambipolar radial electric field, and the bootstrap current in realistic toroidal plasmas. Using a global ?f particle simulation, it is found that the conventional local, linear gradient-flux relation is broken for the ion thermal transport near the magnetic axis. With regard to the transport level, it is found that details of the ion temperature profile determine whether the transport is higher or lower when compared with the predictions of standard neoclassical theory. Particularly, this nonlocal feature is suggested to exist in the National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)], being consistent with NSTX experimental evidence. It is also shown that a large ion temperature gradient can increase the bootstrap current. When the plasma rotation is taken into account, the toroidal rotation gradient can drive an additional parallel flow for the ions and then additional bootstrap current, either positive or negative, depending on the gradient direction. Compared with the carbon radial force balance estimate for the neoclassical poloidal flow, our nonlocal simulation predicts a significantly deeper radial electric field well at the location of an internal transport barrier of an NSTX discharge.

  4. A collective scattering system for measuring electron gyroscale fluctuations on the National Spherical Torus Experiment

    SciTech Connect

    Smith, D. R.; Mazzucato, E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States); Lee, W.; Park, H. K. [Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of); Domier, C. W.; Luhmann, N. C. Jr. [Department of Applied Science, University of California at Davis, Davis, California 95616-8254 (United States)

    2008-12-15

    A collective scattering system has been installed on the National Spherical Torus Experiment (NSTX) to measure electron gyroscale fluctuations in NSTX plasmas. The system measures fluctuations with k{sub perpendicular}{rho}{sub e} < or approx. 0.6 and k{sub perpendicular} < or approx. 20 cm{sup -1}. Up to five distinct wavenumbers are measured simultaneously, and the large toroidal curvature of NSTX plasmas provides enhanced spatial localization. Steerable optics can position the scattering volume throughout the plasma from the magnetic axis to the outboard edge. Initial measurements indicate rich turbulent dynamics on the electron gyroscale. The system will be a valuable tool for investigating the connection between electron temperature gradient turbulence and electron thermal transport in NSTX plasmas.

  5. Overview of Results from the National Spherical Torus Experiment (NSTX)

    SciTech Connect

    Gates, D; Ahn, J; Allain, J; Andre, R; Bastasz, R; Bell, M; Bell, R; Belova, E; Berkery, J; Betti, R; Bialek, J; Biewer, T; Bigelow, T; Bitter, M; Boedo, J; Bonoli, P; Bozzer, A; Brennan, D; Breslau, J; Brower, D; Bush, C; Canik, J; Caravelli, G; Carter, M; Caughman, J; Chang, C; Choe, W; Crocker, N; Darrow, D; Delgado-Aparicio, L; Diem, S; D'Ippolito, D; Domier, C; Dorland, W; Efthimion, P; Ejiri, A; Ershov, N; Evans, T; Feibush, E; Fenstermacher, M; Ferron, J; Finkenthal, M; Foley, J; Frazin, R; Fredrickson, E; Fu, G; Funaba, H; Gerhardt, S; Glasser, A; Gorelenkov, N; Grisham, L; Hahm, T; Harvey, R; Hassanein, A; Heidbrink, W; Hill, K; Hillesheim, J; Hillis, D; Hirooka, Y; Hosea, J; Hu, B; Humphreys, D; Idehara, T; Indireshkumar, K; Ishida, A; Jaeger, F; Jarboe, T; Jardin, S; Jaworski, M; Ji, H; Jung, H; Kaita, R; Kallman, J; Katsuro-Hopkins, O; Kawahata, K; Kawamori, E; Kaye, S; Kessel, C; Kim, J; Kimura, H; Kolemen, E; Krasheninnikov, S; Krstic, P; Ku, S; Kubota, S; Kugel, H; La Haye, R; Lao, L; LeBlanc, B; Lee, W; Lee, K; Leuer, J; Levinton, F; Liang, Y; Liu, D; Luhmann, N; Maingi, R; Majeski, R; Manickam, J; Mansfield, D; Maqueda, R; Mazzucato, E; McCune, D; McGeehan, B; McKee, G; Medley, S; Menard, J; Menon, M; Meyer, H; Mikkelsen, D; Miloshevsky, G; Mitarai, O; Mueller, D; Mueller, S; Munsat, T; Myra, J; Nagayama, Y; Nelson, B; Nguyen, X; Nishino, N; Nishiura, M; Nygren, R; Ono, M; Osborne, T; Pacella, D; Park, H; Park, J; Paul, S; Peebles, W; Penaflor, B; Peng, M; Phillips, C; Pigarov, A; Podesta, M; Preinhaelter, J; Ram, A; Raman, R; Rasmussen, D; Redd, A; Reimerdes, H; Rewoldt, G; Ross, P; Rowley, C; Ruskov, E; Russell, D; Ruzic, D; Ryan, P; Sabbagh, S; Schaffer, M; Schuster, E; Scott, S; Shaing, K; Sharpe, P; Shevchenko, V; Shinohara, K; Sizyuk, V; Skinner, C; Smirnov, A; Smith, D; Smith, S; Snyder, P; Soloman, W; Sontag, A; Soukhanovskii, V; Stoltzfus-Dueck, T; Stotler, D; Strait, T; Stratton, B; Stutman, D; Takahashi, R; Takase, Y; Tamura, N; Tang, X; Taylor, G; Taylor, C; Ticos, C; Tritz, K; Tsarouhas, D; Turrnbull, A; Tynan, G; Ulrickson, M; Umansky, M; Urban, J; Utergberg, E; Walker, M; Wampler, W; Wang, J; Wang, W; Weland, A

    2009-01-05

    The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high {beta} operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies confirm the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance l{sub i} {approx} 0.4 with strong shaping ({kappa} {approx} 2.7, {delta} {approx} 0.8) with {beta}{sub N} approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction f{sub NI} {approx} 71%. Instabilities driven by super-Alfvenic ions are an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvenic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. RWM/RFA feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with {beta} above the no-wall limit. The impact of n > 1 error fields on stability is a important result for ITER. Other highlights are: results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas, and coupling of CHI plasmas to OH ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.

  6. Beta-limiting instabilities and global mode stabilization in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Sabbagh, S. A.; Bell, R. E.; Bell, M. G.; Bialek, J.; Glasser, A. H.; LeBlanc, B.; Menard, J. E.; Paoletti, F.; Stutman, D.; Fredrickson, E.; Garofalo, A. M.; Gates, D.; Kaye, S. M.; Lao, L. L.; Maingi, R.; Mueller, D.; Navratil, G.; Ono, M.; Peng, M.; Synakowski, E.; Zhu, W.

    2002-05-01

    Research on the stability of spherical torus plasmas at and above the no-wall beta limit is being addressed on the National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 40, 557 (2000)], that has produced low aspect ratio plasmas, R/a˜1.27 at plasma current exceeding 1.4 MA with high energy confinement (TauE/TauE_ITER89P>2). Toroidal and normalized beta have exceeded 25% and 4.3, respectively, in q˜7 plasmas. The beta limit is observed to increase and then saturate with increasing li. The stability factor ?N/li has reached 6, limited by sudden beta collapses. Increased pressure peaking leads to a decrease in ?N. Ideal stability analysis of equilibria reconstructed with EFIT [L. L. Lao et al., Nucl. Fusion 25, 1611 (1985)] shows that the plasmas are at the no-wall beta limit for the n=1 kink/ballooning mode. Low aspect ratio and high edge q theoretically alter the plasma stability and mode structure compared to standard tokamak configurations. Below the no-wall limit, stability calculations show the perturbed radial field is maximized near the center column and mode stability is not highly effected by a nearby conducting wall due to the short poloidal wavelength in this region. In contrast, as beta reaches and exceeds the no-wall limit, the mode becomes strongly ballooning with long poloidal wavelength at large major radius and is highly wall stabilized. In this way, wall stabilization is more effective at higher beta in low aspect ratio geometry. The resistive wall mode has been observed in plasmas exceeding the ideal no-wall beta limit and leads to rapid toroidal rotation damping across the plasma core.

  7. Zero point energy on extra dimension: Noncommutative Torus

    E-print Network

    S. Fabi; B. Harms; G. Karatheodoris

    2007-04-25

    In this paper we calculate the zero point energy density experienced by observers on M^4 due to a massless scalar field defined throughout M^4 x T^2_F, where T^2_F are fuzzy extra dimensions. Using the Green's function approach we calculate the energy density for the commutative torus and the fuzzy torus. We calculate then the energy density for the fuzzy torus using the Hamiltonian approach. Agreement is shown between Green's function and Hamiltonian approaches.

  8. Zero point energy on extra dimensions: Noncommutative torus

    Microsoft Academic Search

    S. Fabi; B. Harms; G. Karatheodoris

    2007-01-01

    In this paper we calculate the zero point energy density experienced by observers on M4 due to a massless scalar field defined throughout M4×TF2, where TF2 are fuzzy extra dimensions. Using the Green's function approach we calculate the energy density for the commutative torus and the fuzzy torus. We also calculate the energy density for the fuzzy torus using the

  9. Zero point energy on extra dimensions: Noncommutative torus

    Microsoft Academic Search

    S. Fabi; B. Harms; G. Karatheodoris

    2007-01-01

    In this paper we calculate the zero point energy density experienced by observers on M due to a massless scalar field defined throughout MxT{sub F}², where T{sub F}² are fuzzy extra dimensions. Using the Green's function approach we calculate the energy density for the commutative torus and the fuzzy torus. We also calculate the energy density for the fuzzy torus

  10. Calculations of Neutral Beam Ion Confinement for the National Spherical Torus Experiment

    SciTech Connect

    M.H. Redi; D.S. Darrow; J. Egedal; S.M. Kaye; R.B. White

    2002-06-27

    The spherical torus (ST) concept underlies several contemporary plasma physics experiments, in which relatively low magnetic fields, high plasma edge q, and low aspect ratio combine for potentially compact, high beta and high performance fusion reactors. An important issue for the ST is the calculation of energetic ion confinement, as large Larmor radius makes conventional guiding center codes of limited usefulness and efficient plasma heating by RF and neutral beam ion technology requires minimal fast ion losses. The National Spherical Torus Experiment (NSTX) is a medium-sized, low aspect ratio ST, with R=0.85 m, a=0.67 m, R/a=1.26, Ip*1.4 MA, Bt*0.6 T, 5 MW of neutral beam heating and 6 MW of RF heating. 80 keV neutral beam ions at tangency radii of 0.5, 0.6 and 0.7 m are routinely used to achieve plasma betas above 30%. Transport analyses for experiments on NSTX often exhibit a puzzling ion power balance. It will be necessary to have reliable beam ion calculations to distinguish among the source and loss channels, and to explore the possibilities for new physics phenomena, such as the recently proposed compressional Alfven eigenmode ion heating.

  11. The Microwave Properties of Jovian Clouds: Laboratory Measurement of Aqueous Ammonia (NH4OH) Between 2-8.5 GHz

    Microsoft Academic Search

    Danny Duong; P. G. Steffes

    2010-01-01

    Laboratory measurements of the complex dielectric properties of aqueous ammonia, under conditions characteristic of Jovian clouds, have been made in the 2-8.5 GHz range at temperatures ranging from 24-60 oC and concentrations of 0-8.5% ammonia (NH3) by volume. No previous laboratory experiments have been made to characterize the microwave dielectric properties of aqueous ammonia. Previous models of Jovian microwave emission

  12. A solitary wave theory of the Great Red Spot and other observed features in the Jovian atmosphere

    NASA Technical Reports Server (NTRS)

    Maxworthy, T.; Redekopp, L. G.

    1976-01-01

    It is shown that solitary waves in a planetary zonal shear have a shape and flow field that are virtually identical to those observed around the Red Spot and numerous other features that have been seen in the Jovian atmosphere. It is suggested that the theoretically calculated interaction between solitary waves has many characteristics in common with the observed interactions between these same Jovian features, and available atmospheric models are shown to be consistent with the very restrictive requirements of the theory.

  13. Symmetry groups associated with tilings on a flat torus.

    PubMed

    Loyola, Mark L; De Las Peñas, Ma Louise Antonette N; Estrada, Grace M; Santoso, Eko Budi

    2015-01-01

    This work investigates symmetry and color symmetry properties of Kepler, Heesch and Laves tilings embedded on a flat torus and their geometric realizations as tilings on a round torus in Euclidean 3-space. The symmetry group of the tiling on the round torus is determined by analyzing relevant symmetries of the planar tiling that are transformed to axial symmetries of the three-dimensional tiling. The focus on studying tilings on a round torus is motivated by applications in the geometric modeling of nanotori and the determination of their symmetry groups. PMID:25537393

  14. Pressure limits of an axisymmetric torus

    SciTech Connect

    Yoshikawa, S.

    1986-03-01

    In order to clarify the pressure limit of a toroidal plasma equilibrium in a three-dimensional geometry, an azimuthally symmetric toroidal plasma was considered. In a tokamak-like plasma, the net toroidal current is necessary for a finite ..beta.. plasma equilibrium. If external conductors are used to provide the rotational transform, iota, the plasma pressure is limited to ..beta.. = (iota/2..pi..)/sup 2//2A, where A is the aspect ratio.

  15. Er:YAG Laser: A New Technical Approach to Remove Torus Palatinus and Torus Mandibularis.

    PubMed

    Rocca, J P; Raybaud, H; Merigo, E; Vescovi, P; Fornaini, C

    2012-01-01

    Objective. The aim of this study was to assess the ability of Er:YAG laser to remove by excision torus mandibularis and to smooth torus palatinus exostosis. Materials and Methods. Torus mandibularis (TM) and torus palatinus (TP) were surgically eliminated via the Er:YAG laser using the following parameters: TM: output power ranging from 500 to 1000?mJ, frequency from 20 to 30?Hz, sapphire tips (diameter 0.8?mm), air-water spray (ratio 5/5), pulse duration 150??sec, fluence ranging from 99592?J/cm(2) to 199044,586?J/cm(2). TP: a peeling technique was used to eliminate TP, as excision by slicing being impossible here. Results. TM: excision was obtained after 12730 pulses. TP: smoothing technique took more time compared with excision. Once peeling was considered to be accomplished, the use of a surgical rasp was necessary to eliminate bone spicules that could delay the wound to heal in good conditions. Conclusion. Er:YAG excision (TM) or Er:YAG peeling (TP) are safe clinical techniques easy to practice even if the time required for excision or surface smoothing is more than the time required with bony burs and high speed instruments. PMID:22792500

  16. Prospects for Jovian seismological observations following the impact of comet Shoemaker-Levy 9

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    1994-01-01

    The impact of each fragment of comet SL-9 will produce a downward-propagating pressure wave which will travel at the sound speed through the jovian interior. Since the sound speed increases with depth, most of the energy in the pressure pulse will be strongly refracted and return to the surface, as recently computed by Marley (1994). This wave may in principle be observable as it propagates into the stratosphere, using sufficiently sensitive thermal infrared imaging. If so, it will provide a unique opportunity to constrain models of the jovian interior. This paper extends Marley's calculations to include the effect of the limited spatial resolution which will be characteristic of real observations. The wave pattern on the disk will consist of closely spaced regions of alternating temperature increases and decreases. Spatial averaging will significantly reduce the observed amplitude for resolutions attainable using earth-based telescopes, but the waves should remain above the detection limit.

  17. The phase diagram of hydrogen with other elements, and applications to Jovian planet interiors

    NASA Technical Reports Server (NTRS)

    Hubbard, W. B.

    1988-01-01

    The physical properties of pure hydrogen are studied under conditions appropriate to the interiors of Jupiter and Saturn (pressure of about 10 Mbar, T of about 80,000 K), and of Uranus and Neptune (pressure of about 0.5 Mbar, T of about 5000 K). Metallization of hydrogen takes place in Jupiter and Saturn but not in Uranus and Neptune. Hydrogen will be in a strongly interacting liquid phase in the deep interiors of all of the Jovian planets. Consideration is given to cases of hydrogen mixed with cosmically abundant impurities such as helium, oxygen, and carbon. Observational results for abundances in Jovian planet atmospheres and their possible relation to processes in the deep interior and to flow measurements are discussed.

  18. Surfing on the Edge: Chaos vs. Near-Integrability in the System of Jovian Planets

    E-print Network

    Wayne B. Hayes

    2007-08-21

    We demonstrate that the system of Jovian planets (Sun+Jupiter+Saturn+Uranus+Neptune), integrated for 200 million years as an isolated 5-body system using many sets of initial conditions all within the uncertainty bounds of their currently known positions, can display both chaos and near-integrability. The conclusion is consistent across four different integrators, including several comparisons against integrations utilizing quadruple precision. We demonstrate that the Wisdom-Holman symplectic map using simple symplectic correctors as implemented in Mercury 6.2 (Chambers 1999) gives a reliable characterization of the existence of chaos for a particular initial condition only with timesteps less than about 10 days, corresponding to about 400 steps per orbit. We also integrate the canonical DE405 initial condition out to 5 Gy, and show that it has a Lyapunov Time of 200--400 My, opening the remote possibility of accurate prediction of the Jovian planetary positions for 5 Gy.

  19. Mapping a Luminous Seyfert 1 Dust Torus

    NASA Astrophysics Data System (ADS)

    Willner, Steven; Ashby, Matthew; Haas, Martin; Pozo Nunez, Francisco

    2013-11-01

    Ground-based reverberation mapping of the well-studied Seyfert 1 galaxy WPVS 48 has revealed that the near infrared J+K band variations lag those in the visible B band by ~72 days. The extremely sharp echo suggests a nearly face-on view of the ~1500 K hot dust torus and a surprisingly small apparent dust covering angle <20 deg. Additional ground-based monitoring is scheduled for 2013 November through 2014 May. Measurements will include photometry in visible (UBVRI) and NIR bands (JHK) at 2-day cadence along with spectroscopic monitoring with the 10-m South African Large Telescope. Adding Spitzer/IRAC 3.6 and 4.5 micron monitoring will reveal the echo of cooler (~800 K) dust and of deeply embedded hot dust expected in the optically thick case. The results will confirm or reject AGN models proposing 1) a concave dust torus geometry (by Kawaguchi & Mori); 2) a convex dust torus geometry optically thick at 2 micron (suggested by us), potentially with puffed-up inner rim to explain the 3 micron bump seen in the SEDs of type-1 AGN; and 3) a dust-related origin of the broad line region (by Elitzur & Shlosman and Czerny et al.). We therefore ask for 18 Spitzer visits during the 51-day visibility window in early 2014. Spitzer is needed because 1% photometric repeatability cannot be achieved from the ground in the L+M bands. We apply for DDT because our initial detections of the NIR echoes were made after the regular proposal deadline. Observations of WPVS 48 will complement the sole comparable Spitzer AGN dust reverberation mapping program by observing an object 25 times more luminous.

  20. Curved noncommutative torus and Gauss-Bonnet

    NASA Astrophysics Data System (ADS)

    Dabrowski, Ludwik; Sitarz, Andrzej

    2013-01-01

    We study perturbations of the flat geometry of the noncommutative two-dimensional torus {T}^2_? (with irrational ?). They are described by spectral triples (A_?, H, D), with the Dirac operator D, which is a differential operator with coefficients in the commutant of the (smooth) algebra A? of {T}_?. We show, up to the second order in perturbation, that the ?-function at 0 vanishes and so the Gauss-Bonnet theorem holds. We also calculate first two terms of the perturbative expansion of the corresponding local scalar curvature.

  1. Model of Jovian F region ionosphere (Jovian ionosphere model in offset dipole approximation). Annual report No. 2

    Microsoft Academic Search

    1990-01-01

    The geomagnetic control of the Earth's atmosphere is well understood. In the F-region and the topside ionosphere, non-electrical forces transport plasma along the magnetic field lines only. In consequence, the worldwide distribution of ionization is strongly dependent on the dip angle. For example, the equatorial anomaly is roughly symmetrical about the dipole equator rather than the geographic. The same appears

  2. Spectral Energy Distribution Signatures of Jovian Planets around White Dwarf Stars

    Microsoft Academic Search

    R. Ignace

    2001-01-01

    The problem of detecting Jovian-sized planets orbiting white dwarf stars is considered. Significant IR excesses result from warm Jupiters orbiting a white dwarf of Teff=10,000 K at a distance of ~103 white dwarf radii (corresponding to ~102 Jupiter radii or a few tenths of an AU) with an orbital period of ~100 days. Such a planet will have a 10

  3. Spectrophotometry of the jovian planets and Titan at 300- to 1000-nm wavelength: The methane spectrum

    Microsoft Academic Search

    Erich Karkoschka

    1994-01-01

    Full-disk albedo spectra of the jovian planets and Titan were derived from observations at the European Southern Observatory in July 1993. The spectra extend from 300- to 1000-nm wavelength at 1-nm resolution. The signal-to-noise ratio is approximately 1000 in the visible. The accuracy is 2% for relative and 4% for absolute albedos. Colors and magnitudes were also determined. Some 40-60

  4. The cloud structure of the jovian atmosphere as seen by the Cassini\\/CIRS experiment

    Microsoft Academic Search

    Katia I. Matcheva; Barney J. Conrath; Peter J. Gierasch; F. Michael Flasar

    2005-01-01

    We analyze the thermal infrared spectra of Jupiter obtained by the Cassini-CIRS instrument during the 2000 flyby to infer temperature and cloud density in the jovian stratosphere and upper troposphere. We use an inversion technique to derive zonal mean vertical profiles of cloud absorption coefficient and optical thickness from a narrow spectral window centered at 1392 cm?1 (7.18 ?m). At

  5. The cloud structure of the jovian atmosphere as seen by the Cassini\\/CIRS experiment

    Microsoft Academic Search

    Katia I. Matcheva; Barney J. Conrath; Peter J. Gierasch; F. Michael Flasar

    2005-01-01

    We analyze the thermal infrared spectra of Jupiter obtained by the Cassini-CIRS instrument during the 2000 flyby to infer temperature and cloud density in the jovian stratosphere and upper troposphere. We use an inversion technique to derive zonal mean vertical profiles of cloud absorption coefficient and optical thickness from a narrow spectral window centered at 1392 cm-1 (7.18 mum). At

  6. Gravitational and hydroelastic waves in thomson-delaney cells of the ocean on Jovian Moon Europa

    Microsoft Academic Search

    B. I. Rabinovich

    2011-01-01

    Abstact  The possibility of appearance of hydrothermal cells in the system “Ocean of Jovian Moon Europaits ice crust” was theoretically\\u000a proved by R. Thomson and J. Delaney [8]. We formulated in [11] boundary value problems for planetary gyroscopic waves and\\u000a gravitationally elastic waves in these cells, and the spectrum of nondivergent gyroscopic waves was numerically investigated.\\u000a The present paper is a

  7. Water Ice Lines and the Formation of Giant Moons around Super-Jovian Planets

    NASA Astrophysics Data System (ADS)

    Heller, René; Pudritz, Ralph

    2015-06-01

    Most of the exoplanets with known masses at Earth-like distances to Sun-like stars are heavier than Jupiter, which raises the question of whether such planets are accompanied by detectable, possibly habitable moons. Here we simulate the accretion disks around super-Jovian planets and find that giant moons with masses similar to Mars can form. Our results suggest that the Galilean moons formed during the final stages of accretion onto Jupiter, when the circumjovian disk was sufficiently cool. In contrast to other studies, with our assumptions, we show that Jupiter was still feeding from the circumsolar disk and that its principal moons cannot have formed after the complete photoevaporation of the circumsolar nebula. To counteract the steady loss of moons into the planet due to type I migration, we propose that the water ice line around Jupiter and super-Jovian exoplanets acted as a migration trap for moons. Heat transitions, however, cross the disk during the gap opening within ?104 years, which makes them inefficient as moon traps and indicates a fundamental difference between planet and moon formation. We find that icy moons larger than the smallest known exoplanet can form at about 15–30 Jupiter radii around super-Jovian planets. Their size implies detectability by the Kepler and PLATO space telescopes as well as by the European Extremely Large Telescope. Observations of such giant exomoons would be a novel gateway to understanding planet formation, as moons carry information about the accretion history of their planets.

  8. Measurement of the Rotation Rate of Jovian Planets with Doppler Spectroscopy

    NASA Astrophysics Data System (ADS)

    Reid, Piper

    2013-06-01

    Jupiter and Saturn are the two gas giants in our solar system. These huge planets rotate very quickly and are composed of gas with no rock or ice surface like many of the other planets in our solar system. Determining the rotational velocity of these planets is of interest to scientists as this information can help in the understanding of the origins of these gas giants and the formation of our solar system. With an amateur astronomer’s telescope in a backyard observatory, is it possible to determine the speed of rotation of Jupiter and Saturn by measuring the Doppler shift of the Hydrogen-? emission lines from each side of the planet? Two Jovian planets, Jupiter and Saturn were studied. The rotational velocity was calculated by aligning the spectroscope slit with the equatorial axis of the Jovian planet and capturing a spectrum that shows tilt in the characteristic emission lines then analyzing the tilt of the emission lines and calculating the amount of Doppler shift implied by this spectral shift. By careful use of consumer grade astronomical equipment it is possible for an amateur astronomer to determine the rotational velocity of the Jovian planets from a backyard home observatory in a suburban setting.

  9. RADON TRANSFORM ON THE TORUS AHMED ABOUELAZ AND FRANOIS ROUVIRE

    E-print Network

    Rouvière, François

    RADON TRANSFORM ON THE TORUS AHMED ABOUELAZ AND FRANÇOIS ROUVIÈRE Abstract. We consider the Radon-Ricci spaces etc. We consider here the n-dimensional (at) torus Tn = Rn=Zn and the Radon transform de will thus enter the picture, as in the case of Radon transforms on Zn already studied by the ...rst author

  10. The Enceladus Torus: Saturn's Vaporous Ring T. A. Cassidy

    E-print Network

    The Enceladus Torus: Saturn's Vaporous Ring T. A. Cassidy Top-down view of water vapor ejected from) eject water vapor with escape speed, into Saturn orbit. (similar to how E-ring is formed) Most of this talk will be about what happens to the vapor as it orbits Saturn. 2 #12;3 Enceladus' torus is one

  11. Minimal Liouville Gravity on the Torus via Matrix Models

    E-print Network

    Lev Spodyneiko

    2014-07-14

    In this paper we use recent results on resonance relations between the matrix models and the minimal Liouville gravity to compute the torus correlation numbers in (3,p) minimal Liouville gravity. Namely, we calculate the torus generating partition function of the (3,p) matrix models and use it to obtain the one- and two-point correlation numbers in the minimal Liouville gravity.

  12. Next Step Spherical Torus Experiment (NSST)

    NASA Astrophysics Data System (ADS)

    Ono, Masayuki; Design; Nsst Team

    2002-11-01

    The progress on the on-going Proof-of-Principle and Concept Exploration spherical torus research has been quite productive and rapid in the recent years. In view of these encouraging results, we examine here a possible next step ST (NSST) facility as a successor to the present PoP level experiments such as NSTX. A logical next-step spherical torus (NSST) device is a "performance extension" (PE) stage ST with Ip A = 8 MA (for non-inductively sustained long pulse) and Ip A = 16 MA (for inductively sustained high performance) discharges. These values are similar in Ip A to the PE tokamak devices such as JET. As a PE-class-ST facility, NSST aims to contribute to a timely and cost effective ST and fusion energy development path. One of the important missions of NSST is to support the physics design and construction of a Component Test Facility (CTF) by developing non-inductively start-up and current maintenance operations. One can also envision operations of NSST as a test bed for CTF operational scenario development once the CTF facility becomes operational, and is fully devoted to its component testing mission. The NSST facility can also explore more advanced ST regimes relevant for DEMO and a power plant such as ARIES-ST. To make timely progress toward this goal, the design philosophy of NSST is to give high priority for physics flexibility including ample diagnostic access.

  13. A Spherical Torus Nuclear Fusion Reactor Space Propulsion Vehicle Concept for Fast Interplanetary Piloted and Robotic Missions

    Microsoft Academic Search

    C. H. Williams; S. K. Borowski; L. A. Dudzinski; A. J. Juhasz

    1999-01-01

    A conceptual space vehicle concept to support NASA's 21^st century requirements was designed to enable human, multi-month travel throughout the outer solar system. The design was predicated on an ignited, spherical torus fusion reactor (R=2.5 m; a=1.25 m) burning spin polarized D^3He fuel and operating at high beta (30%). Peaked plasma temperature (50 keV) and number density (5×10^20 m-3) profiles

  14. Observation of Compressional Alfven Modes during Neutral Beam Heating on the National Spherical Torus Experiment

    SciTech Connect

    E.D. Fredrickson; N. Gorelenkov; C.Z. Cheng; R. Bell; D. Darrow; D. Johnson; S. Kaye; B. LeBlanc; J. Menard; S. Kubota; W. Peebles

    2001-10-03

    Neutral-beam-driven compressional Alfven eigenmodes (CAE) at frequencies below the ion cyclotron frequency have been observed and identified for the first time in the National Spherical Torus Experiment (NSTX). The modes are observed as a broad spectrum of nearly equally spaced peaks in the frequency range from approximately 0.2 to approximately 1.2 omega(subscript ''ci''). The frequency has a scaling with toroidal field and plasma density consistent with Alfven waves. The modes have been observed with high bandwidth magnetic pick-up coils and with a reflectometer.

  15. Neutral particle analyzer diagnostic on the National Spherical Torus Experiment

    SciTech Connect

    Medley, S.S.; Roquemore, A.L. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2004-10-01

    The neutral particle analyzer (NPA) diagnostic on the National Spherical Torus Experiment (NSTX) utilizes a PPPL-designed EIIB spectrometer that measures the energy spectra of minority hydrogen and bulk deuterium species simultaneously with 39 energy channels per mass specie and a time resolution of 1 ms. The calibrated energy range is E=0.5-150 keV and the energy resolution varies from {delta}E/E=3%-7% over the surface of the microchannel plate detector. The NPA measures Maxwellian spectra of residual hydrogen to obtain ion temperatures and measures the energetic ion spectra produced by injection of up to 100 keV deuterium neutral beams into deuterium plasmas. The NPA views across the coinjection paths of the three neutral beam sources on NSTX which localizes the measured charge exchange effux to the intersection region. The incorporation of horizontal scanning for the NPA over a sightline tangency range of R{sub tan}=125--75 cm has enabled measurement of the anisotropic energy distribution of the beam ions. Vertical scanning allows measurements to be made from the horizontal midplane through an angle of 26 deg. downward. A description of the NPA diagnostic on NSTX will be presented along with illustrations of measurement capability.

  16. Overview of recent physics results from the National Spherical Torus Experiment (NSTX)

    NASA Astrophysics Data System (ADS)

    Menard, J. E.; Bell, M. G.; Bell, R. E.; Bernabei, S.; Bialek, J.; Biewer, T.; Blanchard, W.; Boedo, J.; Bush, C. E.; Carter, M. D.; Choe, W.; Crocker, N. A.; Darrow, D. S.; Davis, W.; Delgado-Aparicio, L.; Diem, S.; Domier, C. W.; D'Ippolito, D. A.; Ferron, J.; Field, A.; Foley, J.; Fredrickson, E. D.; Gates, D. A.; Gibney, T.; Harvey, R.; Hatcher, R. E.; Heidbrink, W.; Hill, K. W.; Hosea, J. C.; Jarboe, T. R.; Johnson, D. W.; Kaita, R.; Kaye, S. M.; Kessel, C. E.; Kubota, S.; Kugel, H. W.; Lawson, J.; LeBlanc, B. P.; Lee, K. C.; Levinton, F. M.; Luhmann, N. C., Jr.; Maingi, R.; Majeski, R. P.; Manickam, J.; Mansfield, D. K.; Maqueda, R.; Marsala, R.; Mastrovito, D.; Mau, T. K.; Mazzucato, E.; Medley, S. S.; Meyer, H.; Mikkelsen, D. R.; Mueller, D.; Munsat, T.; Myra, J. R.; Nelson, B. A.; Neumeyer, C.; Nishino, N.; Ono, M.; Park, H. K.; Park, W.; Paul, S. F.; Peebles, T.; Peng, M.; Phillips, C.; Pigarov, A.; Pinsker, R.; Ram, A.; Ramakrishnan, S.; Raman, R.; Rasmussen, D.; Redi, M.; Rensink, M.; Rewoldt, G.; Robinson, J.; Roney, P.; Roquemore, A. L.; Ruskov, E.; Ryan, P.; Sabbagh, S. A.; Schneider, H.; Skinner, C. H.; Smith, D. R.; Sontag, A.; Soukhanovskii, V.; Stevenson, T.; Stotler, D.; Stratton, B. C.; Stutman, D.; Swain, D.; Synakowski, E.; Takase, Y.; Taylor, G.; Tritz, K.; von Halle, A.; Wade, M.; White, R.; Wilgen, J.; Williams, M.; Wilson, J. R.; Yuh, H.; Zakharov, L. E.; Zhu, W.; Zweben, S. J.; Akers, R.; Beiersdorfer, P.; Betti, R.; Bigelow, T.; Bitter, M.; Bonoli, P.; Bourdelle, C.; Chang, C. S.; Chrzanowski, J.; Dudek, L.; Efthimion, P. C.; Finkenthal, M.; Fredd, E.; Fu, G. Y.; Glasser, A.; Goldston, R. J.; Greenough, N. L.; Grisham, L. R.; Gorelenkov, N.; Guazzotto, L.; Hawryluk, R. J.; Hogan, J.; Houlberg, W.; Humphreys, D.; Jaeger, F.; Kalish, M.; Krasheninnikov, S.; Lao, L. L.; Lawrence, J.; Leuer, J.; Liu, D.; Oliaro, G.; Pacella, D.; Parsells, R.; Schaffer, M.; Semenov, I.; Shaing, K. C.; Shapiro, M. A.; Shinohara, K.; Sichta, P.; Tang, X.; Vero, R.; Walker, M.; Wampler, W.

    2007-10-01

    The National Spherical Torus Experiment (NSTX) has made considerable progress in advancing the scientific understanding of high performance long-pulse plasmas needed for future spherical torus (ST) devices and ITER. Plasma durations up to 1.6 s (five current redistribution times) have been achieved at plasma currents of 0.7 MA with non-inductive current fractions above 65% while simultaneously achieving ?T and ?N values of 17% and 5.7 (%m T MA-1), respectively. A newly available motional Stark effect diagnostic has enabled validation of current-drive sources and improved the understanding of NSTX 'hybrid'-like scenarios. In MHD research, ex-vessel radial field coils have been utilized to infer and correct intrinsic EFs, provide rotation control and actively stabilize the n = 1 resistive wall mode at ITER-relevant low plasma rotation values. In transport and turbulence research, the low aspect ratio and a wide range of achievable ? in the NSTX provide unique data for confinement scaling studies, and a new microwave scattering diagnostic is being used to investigate turbulent density fluctuations with wavenumbers extending from ion to electron gyro-scales. In energetic particle research, cyclic neutron rate drops have been associated with the destabilization of multiple large toroidal Alfven eigenmodes (TAEs) analogous to the 'sea-of-TAE' modes predicted for ITER, and three-wave coupling processes have been observed for the first time. In boundary physics research, advanced shape control has enabled studies of the role of magnetic balance in H-mode access and edge localized mode stability. Peak divertor heat flux has been reduced by a factor of 5 using an H-mode-compatible radiative divertor, and lithium conditioning has demonstrated particle pumping and results in improved thermal confinement. Finally, non-solenoidal plasma start-up experiments have achieved plasma currents of 160 kA on closed magnetic flux surfaces utilizing coaxial helicity injection.

  17. Advanced Plasma Propulsion for Human Missions to Jupiter

    NASA Technical Reports Server (NTRS)

    Donahue, Benjamin B.; Pearson, J. Boise

    1999-01-01

    This paper will briefly identify a promising fusion plasma power source, which when coupled with a promising electric thruster technology would provide for an efficient interplanetary transfer craft suitable to a 4 year round trip mission to the Jovian system. An advanced, nearly radiation free Inertial Electrostatic Confinement scheme for containing fusion plasma was judged as offering potential for delivering the performance and operational benefits needed for such high energy human expedition missions, without requiring heavy superconducting magnets for containment of the fusion plasma. Once the Jovian transfer stage has matched the heliocentric velocity of Jupiter, the energy requirements for excursions to its outer satellites (Callisto, Ganymede and Europa) by smaller excursion craft are not prohibitive. The overall propulsion, power and thruster system is briefly described and a preliminary vehicle mass statement is presented.

  18. Investigating the plasma environment at Titan's orbit

    Microsoft Academic Search

    H. T. Smith; A. M. Rymer; R. E. Johnson; D. G. Mitchell; A. Wellbrock; A. J. Coates; D. T. Young

    2010-01-01

    Prior to Cassini's arrival at Saturn, nitrogen ions were thought to dominate heavy plasma in Saturn's magnetosphere and that Titan's atmosphere was the source of this nitrogen. Therefore, the presence of a Titan nitrogen torus was anticipated. However, it is now known water-group ions dominate Saturn's heavy ion plasma. While nitrogen ions have been detected beyond the orbit of Rhea,

  19. Progress Towards High Performance, Steady-state Spherical Torus

    SciTech Connect

    M. Ono; M.G. Bell; R.E. Bell; T. Bigelow; M. Bitter; W. Blanchard; J. Boedo; C. Bourdelle; C. Bush; W. Choe; J. Chrzanowski; D.S. Darrow; S.J. Diem; R. Doerner; P.C. Efthimion; J.R. Ferron; R.J. Fonck; E.D. Fredrickson; G.D. Garstka; D.A. Gates; T. Gray; L.R. Grisham; W. Heidbrink; K.W. Hill; D. Hoffman; T.R. Jarboe; D.W. Johnson; R. Kaita; S.M. Kaye; C. Kessel; J.H. Kim; M.W. Kissick; S. Kubota; H.W. Kugel; B.P. LeBlanc; K. Lee; S.G. Lee; B.T. Lewicki; S. Luckhardt; R. Maingi; R. Majeski; J. Manickam; R. Maqueda; T.K. Mau; E. Mazzucato; S.S. Medley; J. Menard; D. Mueller; B.A. Nelson; C. Neumeyer; N. Nishino; C.N. Ostrander; D. Pacella; F. Paoletti; H.K. Park; W. Park; S.F. Paul; Y.-K. M. Peng; C.K. Phillips; R. Pinsker; P.H. Probert; S. Ramakrishnan; R. Raman; M. Redi; A.L. Roquemore; A. Rosenberg; P.M. Ryan; S.A. Sabbagh; M. Schaffer; R.J. Schooff; R. Seraydarian; C.H. Skinner; A.C. Sontag; V. Soukhanovskii; J. Spaleta; T. Stevenson; D. Stutman; D.W. Swain; E. Synakowski; Y. Takase; X. Tang; G. Taylor; J. Timberlake; K.L. Tritz; E.A. Unterberg; A. Von Halle; J. Wilgen; M. Williams; J.R. Wilson; X. Xu; S.J. Zweben; R. Akers; R.E. Barry; P. Beiersdorfer; J.M. Bialek; B. Blagojevic; P.T. Bonoli; M.D. Carter; W. Davis; B. Deng; L. Dudek; J. Egedal; R. Ellis; M. Finkenthal; J. Foley; E. Fredd; A. Glasser; T. Gibney; M. Gilmore; R.J. Goldston; R.E. Hatcher; R.J. Hawryluk; W. Houlberg; R. Harvey; S.C. Jardin; J.C. Hosea; H. Ji; M. Kalish; J. Lowrance; L.L. Lao; F.M. Levinton; N.C. Luhmann; R. Marsala; D. Mastravito; M.M. Menon; O. Mitarai; M. Nagata; G. Oliaro; R. Parsells; T. Peebles; B. Peneflor; D. Piglowski; G.D. Porter; A.K. Ram; M. Rensink; G. Rewoldt; P. Roney; K. Shaing; S. Shiraiwa; P. Sichta; D. Stotler; B.C. Stratton; R. Vero; W.R. Wampler; G.A. Wurden

    2003-10-02

    Research on the Spherical Torus (or Spherical Tokamak) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect-ratio devices, such as the conventional tokamak. The Spherical Tours (ST) experiments are being conducted in various U.S. research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium-size ST research facilities: Pegasus at University of Wisconsin, HIT-II at University of Washington, and CDX-U at Princeton. In the context of the fusion energy development path being formulated in the U.S., an ST-based Component Test Facility (CTF) and, ultimately a Demo device, are being discussed. For these, it is essential to develop high-performance, steady-state operational scenarios. The relevant scientific issues are energy confinement, MHD stability at high beta (B), noninductive sustainment, ohmic-solenoid-free start-up, and power and particle handling. In the confinement area, the NSTX experiments have shown that the confinement can be up to 50% better than the ITER-98-pby2 H-mode scaling, consistent with the requirements for an ST-based CTF and Demo. In NSTX, CTF-relevant average toroidal beta values bT of up to 35% with the near unity central betaT have been obtained. NSTX will be exploring advanced regimes where bT up to 40% can be sustained through active stabilization of resistive wall modes. To date, the most successful technique for noninductive sustainment in NSTX is the high beta-poloidal regime, where discharges with a high noninductive fraction ({approx}60% bootstrap current + neutral-beam-injected current drive) were sustained over the resistive skin time. Research on radio-frequency-based heating and current drive utilizing HHFW (High Harmonic Fast Wave) and EBW (Electron Bernstein Wave) is also pursued on NSTX, Pegasus, and CDX-U. For noninductive start-up, the Coaxial Helicity Injection (CHI), developed in HIT/HIT-II, has been adopted on NSTX to test the method up to Ip {approx} 500 kA. In parallel, start-up using radio-frequency current drive and only external poloidal field coils are being developed on NSTX. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks. Due to its promise for power and particle handling, liquid lithium is being studied in CDX-U as a potential plasma-facing surface for a fusion reactor.

  20. Benchmark experiments on neutron streaming through JET Torus Hall penetrations

    NASA Astrophysics Data System (ADS)

    Batistoni, P.; Conroy, S.; Lilley, S.; Naish, J.; Obryk, B.; Popovichev, S.; Stamatelatos, I.; Syme, B.; Vasilopoulou, T.; contributors, JET

    2015-05-01

    Neutronics experiments are performed at JET for validating in a real fusion environment the neutronics codes and nuclear data applied in ITER nuclear analyses. In particular, the neutron fluence through the penetrations of the JET torus hall is measured and compared with calculations to assess the capability of state-of-art numerical tools to correctly predict the radiation streaming in the ITER biological shield penetrations up to large distances from the neutron source, in large and complex geometries. Neutron streaming experiments started in 2012 when several hundreds of very sensitive thermo-luminescence detectors (TLDs), enriched to different levels in 6LiF/7LiF, were used to measure the neutron and gamma dose separately. Lessons learnt from this first experiment led to significant improvements in the experimental arrangements to reduce the effects due to directional neutron source and self-shielding of TLDs. Here we report the results of measurements performed during the 2013–2014 JET campaign. Data from new positions, at further locations in the South West labyrinth and down to the Torus Hall basement through the air duct chimney, were obtained up to about a 40 m distance from the plasma neutron source. In order to avoid interference between TLDs due to self-shielding effects, only TLDs containing natural Lithium and 99.97% 7Li were used. All TLDs were located in the centre of large polyethylene (PE) moderators, with natLi and 7Li crystals evenly arranged within two PE containers, one in horizontal and the other in vertical orientation, to investigate the shadowing effect in the directional neutron field. All TLDs were calibrated in the quantities of air kerma and neutron fluence. This improved experimental arrangement led to reduced statistical spread in the experimental data. The Monte Carlo N-Particle (MCNP) code was used to calculate the air kerma due to neutrons and the neutron fluence at detector positions, using a JET model validated up to the magnetic limbs. JET biological shield and penetrations, the PE moderators and TLDs were modelled in detail. Different tallying methods were used in the calculations, which are routinely used in ITER nuclear analyses: the mesh tally and the track length estimator with multiple steps calculations using the surface source write/read capability available in MCNP. In both cases, the calculated neutron fluence (C) was compared to the measured fluence (E) and hence C/E comparisons have been obtained and are discussed. These results provide a validation of neutronics numerical tools, codes and nuclear data, used for ITER design.

  1. Progress towards high-performance, steady-state spherical torus

    NASA Astrophysics Data System (ADS)

    Ono, M.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W.; Boedo, J.; Bourdelle, C.; Bush, C.; Choe, W.; Chrzanowski, J.; Darrow, D. S.; Diem, S. J.; Doerner, R.; Efthimion, P. C.; Ferron, J. R.; Fonck, R. J.; Fredrickson, E. D.; Garstka, G. D.; Gates, D. A.; Gray, T.; Grisham, L. R.; Heidbrink, W.; Hill, K. W.; Hoffman, D.; Jarboe, T. R.; Johnson, D. W.; Kaita, R.; Kaye, S. M.; Kessel, C.; Kim, J. H.; Kissick, M. W.; Kubota, S.; Kugel, H. W.; LeBlanc, B. P.; Lee, K.; Lee, S. G.; Lewicki, B. T.; Luckhardt, S.; Maingi, R.; Majeski, R.; Manickam, J.; Maqueda, R.; Mau, T. K.; Mazzucato, E.; Medley, S. S.; Menard, J.; Mueller, D.; Nelson, B. A.; Neumeyer, C.; Nishino, N.; Ostrander, C. N.; Pacella, D.; Paoletti, F.; Park, H. K.; Park, W.; Paul, S. F.; Peng, Y.-K. M.; Phillips, C. K.; Pinsker, R.; Probert, P. H.; Ramakrishnan, S.; Raman, R.; Redi, M.; Roquemore, A. L.; Rosenberg, A.; Ryan, P. M.; Sabbagh, S. A.; Schaffer, M.; Schooff, R. J.; Seraydarian, R.; Skinner, C. H.; Sontag, A. C.; Soukhanovskii, V.; Spaleta, J.; Stevenson, T.; Stutman, D.; Swain, D. W.; Synakowski, E.; Takase, Y.; Tang, X.; Taylor, G.; Timberlake, J.; Tritz, K. L.; Unterberg, E. A.; Von Halle, A.; Wilgen, J.; Williams, M.; Wilson, J. R.; Xu, X.; Zweben, S. J.; Akers, R.; Barry, R. E.; Beiersdorfer, P.; Bialek, J. M.; Blagojevic, B.; Bonoli, P. T.; Carter, M. D.; Davis, W.; Deng, B.; Dudek, L.; Egedal, J.; Ellis, R.; Finkenthal, M.; Foley, J.; Fredd, E.; Glasser, A.; Gibney, T.; Gilmore, M.; Goldston, R. J.; Hatcher, R. E.; Hawryluk, R. J.; Houlberg, W.; Harvey, R.; Jardin, S. C.; Hosea, J. C.; Ji, H.; Kalish, M.; Lowrance, J.; Lao, L. L.; Levinton, F. M.; Luhmann, N. C.; Marsala, R.; Mastravito, D.; Menon, M. M.; Mitarai, O.; Nagata, M.; Oliaro, G.; Parsells, R.; Peebles, T.; Peneflor, B.; Piglowski, D.; Porter, G. D.; Ram, A. K.; Rensink, M.; Rewoldt, G.; Robinson, J.; Roney, P.; Shaing, K.; Shiraiwa, S.; Sichta, P.; Stotler, D.; Stratton, B. C.; Vero, R.; Wampler, W. R.; Wurden, G. A.

    2003-12-01

    Research on the spherical torus (or spherical tokamak) (ST) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect ratio devices, such as the conventional tokamak. The ST experiments are being conducted in various US research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium sized ST research facilities: PEGASUS at University of Wisconsin, HIT-II at University of Washington, and CDX-U at Princeton. In the context of the fusion energy development path being formulated in the US, an ST-based Component Test Facility (CTF) and, ultimately a Demo device, are being discussed. For these, it is essential to develop high performance, steady-state operational scenarios. The relevant scientific issues are energy confinement, MHD stability at high beta (bgr), non-inductive sustainment, Ohmic-solenoid-free start-up, and power and particle handling. In the confinement area, the NSTX experiments have shown that the confinement can be up to 50% better than the ITER-98-pby2 H-mode scaling, consistent with the requirements for an ST-based CTF and Demo. In NSTX, CTF-relevant average toroidal beta values bgrT of up to 35% with a near unity central bgrT have been obtained. NSTX will be exploring advanced regimes where bgrT up to 40% can be sustained through active stabilization of resistive wall modes. To date, the most successful technique for non-inductive sustainment in NSTX is the high beta poloidal regime, where discharges with a high non-inductive fraction (~60% bootstrap current+NBI current drive) were sustained over the resistive skin time. Research on radio-frequency (RF) based heating and current drive utilizing high harmonic fast wave and electron Bernstein wave is also pursued on NSTX, PEGASUS, and CDX-U. For non-inductive start-up, the coaxial helicity injection, developed in HIT/HIT-II, has been adopted on NSTX to test the method up to Ip ~ 500 kA. In parallel, start-up using a RF current drive and only external poloidal field coils are being developed on NSTX. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks. Due to its promise for power and particle handling, liquid lithium is being studied in CDX-U as a potential plasma-facing surface for a fusion reactor.

  2. A Megawatt-level 28z GHz Heating System For The National Spherical Torus Experiment Upgrade

    SciTech Connect

    Taylor, Gary [PPPL

    2014-04-01

    The National Spherical Torus Experiment Upgrade (NSTX-U) will operate at axial toroidal fields of < 1 T and plasma currents, Ip < 2 MA. The development of non-inductive (NI) plasmas is a major long-term research goal for NSTX-U. Time dependent numerical simulations of 28 GHz electron cyclotron (EC) heating of low density NI start-up plasmas generated by Coaxial Helicity Injection (CHI) in NSTX-U predict a significant and rapid increase of the central electron temperature (Te(0)) before the plasma becomes overdense. The increased Te(0) will significantly reduce the Ip decay rate of CHI plasmas, allowing the coupling of fast wave heating and neutral beam injection. A megawatt-level, 28 GHz electron heating system is planned for heating NI start-up plasmas in NSTX-U. In addition to EC heating of CHI start-up discharges, this system will be used for electron Bernstein wave (EBW) plasma start-up, and eventually for EBW heating and current drive during the Ip flattop.

  3. Dusty plasma investigations as a tool for diagnostic Space Weather conditions for a future planetary missions

    NASA Astrophysics Data System (ADS)

    Atamaniuk, Barbara; Rothkaehl, Hanna; Schreiber, Roman; Wahlund, Jan-Erik

    2014-05-01

    I shortly present the overview of our knowledge about the dust and dusty plasma in the Jovian system and the main concept of JUICE (JUpiter ICy moon Explorer) mission. Then I concentrate on the Radio & Plasma Waves Investigation ( RPWI) selected for implementation on the JUICE mission. RPWI consists of a highly integrated instrument package that provides a whole set of plasma and fields measurements. The RPWI instrument has outstanding new capabilities not previously available to outer planet missions, and that would address many fundamental planetary science objectives. Specifically, RPWI would be able to study dusty plasma processes in the Jovian magnetosphere and the exospheres of Ganymede, Europa and Callisto. Moreover, RPWI will search for exhaust plumes from cracks on the icy moons, as well as ?m-sized dust and related dust-plasma surface interaction processes occurring near the icy moons of Jupiter. This research is partly supported by grant O N517 418440

  4. A torus bifurcation theorem with symmetry

    NASA Technical Reports Server (NTRS)

    Vangils, S. A.; Golubitsky, M.

    1989-01-01

    Hopf bifurcation in the presence of symmetry, in situations where the normal form equations decouple into phase/amplitude equations is described. A theorem showing that in general such degeneracies are expected to lead to secondary torus bifurcations is proved. By applying this theorem to the case of degenerate Hopf bifurcation with triangular symmetry it is proved that in codimension two there exist regions of parameter space where two branches of asymptotically stable two-tori coexist but where no stable periodic solutions are present. Although a theory was not derived for degenerate Hopf bifurcations in the presence of symmetry, examples are presented that would have to be accounted for by any such general theory.

  5. Electromagnetic noise and radio wave propagation below 100 kHz in the Jovian atmosphere. I - The equatorial region

    NASA Technical Reports Server (NTRS)

    Rinnert, K.; Axford, W. I.; Lanzerotti, L. J.; Krider, E. P.; Uman, M. A.; Dehmel, G.; Gliem, F. O.

    1979-01-01

    The Galileo satellite program includes the delivery of an entry probe to the Jovian equatorial atmosphere in mid-1985. Optical and RF sensors for a lightning detection system are included as a part of the probe experimental payload. In this paper, calculations of the RF wave propagation and reflection characteristics of the equatorial Jovian atmosphere and ionosphere for frequencies less than 100 kHz are presented. It is shown that wave propagation is limited to line-of-sight and one-hop from the ionosphere. Results are also presented of a statistical treatment of the RF wave power densities for the case of a finite number of events and for the case of a uniformly distributed source. The results can be applied to specific RF experiment configurations concerned with establishing the statistical characteristics of Jovian lightning.

  6. The Properties of Jovian Trojan Asteroids Listed in SDSS Moving Object Catalog 3

    E-print Network

    Gy. M. Szabo; Z. Ivezic; M. Juric; R. Lupton

    2007-03-01

    We analyze 1187 observations of about 860 unique candidate Jovian Trojan asteroids listed in the 3rd release of Sloan Digital Sky Survey (SDSS) Moving Object Catalog. The sample is complete at the faint end to r=21.2 mag (apparent brightness) and H=13.8 (absolute brightness, approximately corresponding to 10 km diameter). A subset of 297 detections of previously known Trojans were used to design and optimize a selection method based on observed angular velocity that resulted in the remaining objects. Using a sample of objects with known orbits, we estimate that the candidate sample contamination is about 3%. The well-controlled selection effects, the sample size, depth and accurate five-band UV-IR photometry enabled several new findings and the placement of older results on a firmer statistical footing. We find that there are significantly more asteroids in the leading swarm (L4) than in the trailing swarm (L5): N(L4)/N(L5)=1.6$\\pm$0.1, independently of limiting object's size. The overall counts normalization suggests that there are about as many Jovians Trojans as there are main-belt asteroids down to the same size limit, in agreement with earlier estimates. We find that Trojan asteroids have a remarkably narrow color distribution (root-mean-scatter of only $\\sim$0.05 mag) that is significantly different from the color distribution of the main-belt asteroids. The color of Trojan asteroids is correlated with their orbital inclination, in a similar way for both swarms, but appears uncorrelated with the object's size. We extrapolate the results presented here and estimate that Large Synoptic Survey Telescope will determine orbits, accurate colors and measure light curves in six photometric bandpasses for about 100,000 Jovian Trojan asteroids.

  7. Electrostatic Charging of Insulating Rods and Resulting Particle Transport in the Columbia Non-neutral Torus

    NASA Astrophysics Data System (ADS)

    Senter, Aaron; Rath, Nikolaus; Brenner, Paul; Sarasola, Xabier; Pedersen, Thomas

    2009-11-01

    The Columbia Non-neutral Torus (CNT) is a stellarator created to study non-neutral plasmas confined on magnetic surfaces. To create and diagnose the electron plasma, filaments supported by ceramic rods are inserted into the plasma. These rods charge negatively allowing particles to E xB drift across the confining magnetic surfaces and out of the plasma. A simple model of this process has yielded good qualitative agreement with experimentally observed radial transport[1]. However, when the rod is retracted, it perturbs the plasma more than expected. To better understand the rod perturbations, externally biased conducting rods are now being used. We find the effect of the ceramic rods by measuring the increase in filament emission current with a rod installed. Comparing the radial transport rates of the ceramic and conducting rods, we aim to understand the charge distribution on the former, and to minimize the rod driven transport. Initial experiments show that a uniformly biased rod does not reproduce the transport observed. Experiments using a rod with a varying radial potential profile are being conducted and will be reported on. [1] J.W. Berkery et al., Phys. Plasmas 14, 062503 (2007).

  8. Discovery of Jovian dust streams and interstellar grains by the Ulysses spacecraft

    NASA Technical Reports Server (NTRS)

    Gruen, E.; Zook, H. A.; Baguhl, M.; Balogh, A.; Bame, S. J.; Fechtig, H.; Forsyth, R.; Hanner, M. S.; Horanyi, M.; Kissel, J.

    1993-01-01

    Within 1 AU from Jupiter, the dust detector aboard the Ulysses spacecraft during the flyby on February 8, 1992 recorded periodic bursts of submicron dust particles with durations ranging from several hours to two days and occurring at about monthly intervals. These particles arrived at Ulysses in collimate streams radiating from close to the line-of-sight direction to Jupiter, suggesting a Jovian origin for the periodic bursts. Ulysses also detected a flux of micron-sized dust particles moving in high-velocity retrograde orbits. These grains are identified here as being of interstellar origin.

  9. Auroral signature of comet Shoemaker-Levy 9 in the jovian magnetosphere.

    PubMed

    Prangé, R; Engle, I M; Clarke, J T; Dunlop, M; Ballester, G E; Ip, W H; Maurice, S; Trauger, J

    1995-03-01

    The electrodynamic interaction of the dust and gas comae of comet Shoemaker-Levy 9 with the jovian magnetosphere was unique and different from the atmospheric effects. Early theoretical predictions of auroral-type processes on the comet magnetic field line and advanced modeling of the time-varying morphology of these lines allowed dedicated observations with the Hubble Space Telescope Wide Field Planetary Camera 2 and resulted in the detection of a bright auroral spot. In that respect, this observation of the surface signature of an externally triggered auroral process can be considered as a "magnetospheric active experiment" on Jupiter. PMID:7871430

  10. High-energy electron testing of CCDs for a Jovian science mission

    NASA Astrophysics Data System (ADS)

    Becker, Heidi N.; Alexander, James W.; Elliott, Tom

    2005-08-01

    We present results of CCD radiation testing for a proposed Jovian mission. Samples of two candidate star tracker CCDs were irradiated with 10-MeV and 50-MeV electrons at Rensselaer Polytechnic Institute's Gaerttner LINAC. Differences in displacement damage effects on CCD parameters and star tracker performance are discussed for these two energies. Dark current, charge transfer efficiency (CTE), hot pixels, and flat-band voltage shifts are examined. Our electron data is compared to proton irradiation data taken by other experimenters. 10-MeV electron-induced transient data are also discussed.

  11. Affirmation of triggered Jovian radio emissions and their attribution to corotating radio lasers

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1985-01-01

    It is argued that the original statistical evidence for the existence of triggered radio emissions and corotating radio lasers on Jupiter remains valid notwithstanding the critique of Desch and Kaiser (1985). The Voyager radio spectrograms used to identify the triggered emissions are analyzed and the results are discussed. It is shown that the critique by Desch and Kaiser is unjustified because it is not based on the original event criteria, i.e., the correlation between the occurrence of Jovian auroral kilometric radiation and fast-drift type III solar bursts in the same frequency.

  12. Troposphere-stratosphere interactions in a one-dimensional model of Jovian photochemistry

    NASA Technical Reports Server (NTRS)

    Landry, Bridget; Yung, Yuk L.; Allen, Mark

    1991-01-01

    The case of a chemically unreactive species flowing downward through the stratosphere and troposphere with a constant flux is presently treated by a one-dimensional Jovian atmosphere model which encompasses the coupling between a rapidly mixed troposphere and a stagnant stratosphere, so that the contrast between the peak stratosphere and tropopause concentrations is reflective of the variation between the lower stratosphere and upper troposphere eddy diffusion coefficients. Numerical simulations of unreactive CO and C2H6 species indicate that upper troposphere abundances may possess a substantial photochemical contribution. The implications of these modeling results for higher spectral resolution observations are noted.

  13. Study of Turbulent Fluctuations Driven by the Electron Temperature Gradient in the National Spherical Torus Experiment

    SciTech Connect

    Mazzucato, E.; Bell, R. E.; Ethier, S.; Hosea, J. C.; Kaye, S. M.; LeBlanc, B. P.; Lee, W. W.; Ryan, P. M.; Smith, D. R.; Wang, W. X.; Wilson, J. R.

    2009-03-26

    Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from a short-scale turbulence driven by the electron temperature gradient. To check whether this turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) show the existence of density fluctuations in the range of wave numbers k??e=0.1-0.4, corresponding to a turbulence scale length of the order of the collisionless skin depth. Experimental observations and agreement with numerical results from the linear gyro-kinetic GS2 code indicate that the observed turbulence is driven by the electron temperature gradient. These turbulent fluctuations were not observed at the location of an internal transport barrier driven by a negative magnetic shear.

  14. Modification Of The Electron Energy Distribution Function During Lithium Experiments On The National Spherical Torus Experiment

    SciTech Connect

    Jaworski, M A; Gray, T K; Kaita, R; Kallman, J; Kugel, H; LeBlanc, B; McLean, A; Sabbagh, S A; Soukanovskii, V; Stotler, D P

    2011-06-03

    The National Spherical Torus Experiment (NSTX) has recently studied the use of a liquid lithium divertor (LLD). Divertor Langmuir probes have also been installed for making measurements of the local plasma conditions. A non-local probe interpretation method is used to supplement the classical probe interpretation and obtain measurements of the electron energy distribution function (EEDF) which show the occurrence of a hot-electron component. Analysis is made of two discharges within a sequence that exhibited changes in plasma fueling efficiency. It is found that the local electron temperature increases and that this increase is most strongly correlated with the energy contained within the hot-electron population. Preliminary interpretative modeling indicates that kinetic effects are likely in the NSTX.

  15. Numerical investigation of electron trajectories in the Columbia Non-neutral Torus

    SciTech Connect

    Durand de Gevigney, Benoit; Sunn Pedersen, Thomas; Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York 10027 (United States)

    2009-12-15

    The confinement of pure electron plasmas in the Columbia Non-neutral Torus (CNT) [T. Sunn Pedersen et al., Fusion Sci. Technol. 50, 372 (2006)] can be enhanced by the large radial electric field due to space charge. However the benefits are limited by two effects: (1) The E-vectorxB-vector precession can, at low B-fields, resonate with the particle motion along the magnetic field lines, which gives large excursions in the trajectories. (2) Variations in the electric potential on magnetic surfaces, inherent to CNT equilibrium, add to the complexity of the trajectories and can also lead to large excursions. The second effect is sensitive to the conductive structures outside the plasma boundary. Results from a new code to investigate electron trajectories in the magnetic and electric field expected in CNT are presented.

  16. Realizing "2001: A Space Odyssey": Piloted Spherical Torus Nuclear Fusion Propulsion

    NASA Technical Reports Server (NTRS)

    Williams, Craig H.; Dudzinski, Leonard A.; Borowski, Stanley K.; Juhasz, Albert J.

    2005-01-01

    A conceptual vehicle design enabling fast, piloted outer solar system travel was created predicated on a small aspect ratio spherical torus nuclear fusion reactor. The initial requirements were satisfied by the vehicle concept, which could deliver a 172 mt crew payload from Earth to Jupiter rendezvous in 118 days, with an initial mass in low Earth orbit of 1,690 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including artificial gravity payload, central truss, nuclear fusion reactor, power conversion, magnetic nozzle, fast wave plasma heating, tankage, fuel pellet injector, startup/re-start fission reactor and battery bank, refrigeration, reaction control, communications, mission design, and space operations. Detailed fusion reactor design included analysis of plasma characteristics, power balance/utilization, first wall, toroidal field coils, heat transfer, and neutron/x-ray radiation. Technical comparisons are made between the vehicle concept and the interplanetary spacecraft depicted in the motion picture 2001: A Space Odyssey.

  17. Direct reading fast microwave interferometer for ELMO Bumpy Torus

    SciTech Connect

    Uckan, T.

    1984-11-01

    A simple and inexpensive 4-mm direct reading fast (rise timeapprox.100 ..mu..s) microwave interferometer is described. The system is particularly useful for density measurements on the ELMO Bumpy Torus (EBT) during pulsed operation.

  18. Recent Progress on Spherical Torus Research and Implications for Fusion Energy Development Path

    NASA Astrophysics Data System (ADS)

    Ono, Masayuki

    2014-10-01

    The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A =R0 / a) reduced to A near 1.5, well below the normal tokamak operating range of A equal to 2.5 or greater. As the aspect ratio is reduced, the ideal tokamak beta (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural plasma elongation which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to the longer term goal of an attractive fusion energy power source. Since the start of the two mega-ampere class ST facilities in 2000, the National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in the UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all areas of fusion research, including fundamental fusion energy science as well as technological innovation. These results suggest exciting future prospects for ST research in both the near and longer term. The talk will summarize the key physics results from worldwide ST experiments, and describe ST community plans to provide the database for FNSF design while improving predictive capabilities for ITER and beyond. This work supported by DoE Contract No. DE-AC02-09CH11466.

  19. The search continues for a Titan-generated Nitrogen Torus in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Johnson, R. E.; Rymer, A. M.; Lewis, G.; Coates, A. J.; Mitchell, D. G.; Young, D. T.

    2012-12-01

    Saturn's largest moon, Titan, possesses a dense relatively unprotected nitrogen rich atmosphere with no detected intrinsic magnetic field. Therefore, despite the inability of pre-Cassini observations to detect nitrogen in Saturn's magnetosphere , it was logically assumed that nitrogen particles from Titan's atmosphere would form a large toriodal gas cloud. However, Cassini observations have confirmed water-group ions dominate Saturn's heavy ion magnetospheric plasma. While nitrogen ions have been detected beyond the orbit of Rhea, these ions appear to be primarily originating from the Enceladus plumes with little nitrogen plasma detected in the magnetosphere near Titan's orbit. In fact, pick-up oxygen ions from Enceladus are much more abundant than nitrogen in Titan's orbit. These results appear inconsistent with the expectation that Titan's dense relatively unprotected atmosphere should provide a significant source of heavy particles to Saturn's magnetosphere. Resolving this inconsistency could provide import insight into atmospheric loss. In this talk, we expand on our previous research that categorizes the plasma environments near Titan to include all locations along Titan's orbit. Using these categories, we develop characteristic plasma spectra of each type of environment, update ionization lifetimes for each region and apply these results in a 3D Monte Carlo model to more accurately examine the fate of nitrogen and methane escaping Titan's atmosphere to support the possible presence of a Titan torus despite the lack of observations. We also present preliminary Cassini data analysis that looks for the presence of a nitrogen torus as well as the relative ion composition at increasing distances from Titan. This work is supported by the NASA Cassini Data Analysis Program and NASA JPL contract 1243218 for Cassini MIMI and CAPS investigation.

  20. Development of a repetitive compact torus injector

    NASA Astrophysics Data System (ADS)

    Onchi, Takumi; McColl, David; Dreval, Mykola; Rohollahi, Akbar; Xiao, Chijin; Hirose, Akira; Zushi, Hideki

    2013-10-01

    A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. This work has been sponsored by the CRC and NSERC, Canada.

  1. The magnetospheres of the outer planets

    SciTech Connect

    Mcnutt, R.L., Jr. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Research on the magnetospheres of all of the outer planets including Jupiter, Uranus, Neptune, and Pluto is reviewed for the 1987-1990 time period. Particular attention is given to magnetospheric structure, plasma transport, Jovian aurora, Io and the plasma torus, Titan and its magnetospheric interactions, rings and dusty plasmas, magnetospheric convection, and satellite interactions.

  2. A new limit on the observed amplitude of Jovian global oscillations

    NASA Astrophysics Data System (ADS)

    Moretti, P. F.; Cacciani, A.; Dolci, M.; Giuliani, C.

    1999-09-01

    Doppler observations of Jupiter carried out in 1996 are reported [1]. A magneto-optical filter has been used providing the signals on the opposite wings of the Sodium D-lines (B, R) and the continuum reference signal. The two computed quantities cal R=(B-R)/(B+R) and cal S=(B+R)/conti\\-nuum have permitted to discriminate between oscillation and albedo "modes" and to compare the results with the previous ones obtained in 1991 [3] and 1993 [2]. A new upper limit on the modes amplitude has been setted at ~ 2 m s(-1) . The features of the intensity fluctuations in the power spectrum are due probably to albedo variations on Jupiter's surface and to instrumental effects. The authors thank the Ministero della Pubblica Istruzione and the Osservatorio Astronomico "V.Cerulli" di Teramo for financial support. References [1] Cacciani A., Moretti P. F., Dolci M., D'Alessio F., Giuliani C., Micolucci E., Di Cianno A., 1999: Search for global oscillations on Jupiter with a double-cell Sodium Magneto-Optical Filter, submitted to Astron. Astrophys. [2] Mosser B., Mekarnia D., Maillard J. P., Gay J., Gautier D., Delache Ph., 1993: Seismological observations with a Fourier transform spectrometer: detection of Jovian oscillations, Astron. Astrophys., 267, 604 [3] Schmider F. X., Mosser B., Fossat E., 1991: Possible detection of Jovian global oscillations, Astron. Astrophys., 248, 281}

  3. High pH, ammonia toxicity, and the search for life on the Jovian planets

    NASA Technical Reports Server (NTRS)

    Deal, P. H.; Souza, K. A.; Mack, H. M.

    1975-01-01

    The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural environments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, urvival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is two to three orders of magnitude longer than for E. coli. Results support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

  4. Copernicus measurement of the Jovian Lyman-alpha emission and its aeronomical significance

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.; Kerr, R. B.; Upson, W. L., II; Festou, M. C.; Donahue, T. M.; Barker, E. S.; Cochran, W. D.; Bertaux, J. L.

    1982-01-01

    It is pointed out that the intensity of the Lyman-alpha emission is a good indicator of the principal aeronomical processes on the major planets. The high-resolution ultraviolet spectrometer aboard the Orbiting Astronomical Observatory Copernicus was used in 1980 April and May to detect the Jovian Lyman-alpha emission by spectroscopically discriminating it from other Doppler shifted Lyman-alpha emissions such as those of the geocorona, and the interplanetary medium. Taking into consideration the reported emission data, it appears that an unusually large energy input due to the particle precipitation in the auroral region must have been responsible for the large observed Lyman-alpha intensity during the Voyager encounter. At most other times, the observed Jovian Lyman-alpha intensity can be explained, within the range of statistical uncertainty, by a model that takes into consideration the solar EUV flux, the solar Lyman-alpha flux, the high exospheric temperature, and the eddy diffusion coefficient without energy input from the auroral sources.

  5. Dispersion-like phenomena in Jovian decametric S-bursts: Tabooed Facts

    E-print Network

    Arkhypov, Oleksiy V

    2014-01-01

    The dominant viewpoint on Jovian decametric S-burst emission neglects the time delay of the radiation, although its base theory of electron cyclotron maser instability allows a significant decreasing of X-mode group velocity near the cutoff frequency at the bottom of source region. We searched for effects of the frequency-related delay of radiation in broadband Jovian radio storms consisting of periodic S-bursts (S-burst trains) at 16 to 30 MHz. It was found that up to 1% of bursts in a train are of distorted meandering shape in dynamic spectrum, where the emission from one radio source was observed at several frequencies simultaneously. It is difficult to explain such spectra in terms of radio waves beaming or causality without significant frequency-related delay of radio emission. We found experimentally that the frequency drift rate of middle lines of such events coincides with the drift rate of disturbances in common S-bursts. This indicates a general distortion of the dynamic spectrum of S-bursts. As a r...

  6. Dynamical Evolution of Pedestal Parameters in ELMy H-mode in the National Spherical Torus Experiment

    SciTech Connect

    Diallo, A; Kubota, S; Sontag, A; Osborne, T; Podesta, M; Bell, R E; LeBlanc, B P; Menard, J

    2011-07-27

    Characterizations of the pedestal parameter dynamics throughout the edge localized modes(ELM) cycles are performed on the National Spherical Torus Experiment (NSTX, [M. Ono et al., Nucl. Fusion 40, 557 (2000)]). A clear buildup of the pedestal height is observed between ELMs for three di erent plasma currents, which tends to saturate prior to the onset of ELM at low and medium plasma current. Similarly, the pedestal width increases with no clear evidence of saturation during an ELM cycle. The maximum pedestal gradient increases as a function of plasma current, reaches a nominal value after the ELM crash, and remains constant until the end of the ELM cycle. The pedestal height just prior to the onset of ELM is shown to increase quadratically with plasma current. The pedestal width ? is proportional to the square-root of the poloidal ? at the top of the pedestal. Coherent density uctuations strongly increasing at the plasma edge are observed to be maximum after the ELM crash and to decay during the rest of the ELM cycle. Finally, the pedestal parameters evolution during the ELM cycle as well as the scaling with Ip of the pedestal pressure prior to the onset ELM are found to be qualitatively consistent with the peeling ballooning theory.

  7. Crewed Mission to Callisto Using Advanced Plasma Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Adams, R. B.; Statham, G.; White, S.; Patton, B.; Thio, Y. C. F.; Santarius, J.; Alexander, R.; Fincher, S.; Polsgrove, T.; Chapman, J.

    2003-01-01

    This paper describes the engineering of several vehicles designed for a crewed mission to the Jovian satellite Callisto. Each subsystem is discussed in detail. Mission and trajectory analysis for each mission concept is described. Crew support components are also described. Vehicles were developed using both fission powered magneto plasma dynamic (MPD) thrusters and magnetized target fusion (MTF) propulsion systems. Conclusions were drawn regarding the usefulness of these propulsion systems for crewed exploration of the outer solar system.

  8. Transfer, adaptation and further development of terrestrial ocean vehicle technology for the exploration of the Jovian Moon Europa

    Microsoft Academic Search

    C. Lange; L. Richter

    2009-01-01

    In this paper, we analyze a scenario, in which a hydrobot would be sent through the several kilometers thick ice layer of the Jovian Moon Europa, integrated in a melting probe, and once reaching the ocean, would perform a highly autonomous investigation of its habitability. The hydrobot would be either swimming or driving at the bottom of the ocean or

  9. Constraints on the presence of volatiles in Ganymede and Callisto from an evolutionary turbulent model of the Jovian subnebula

    Microsoft Academic Search

    Olivier Mousis; Daniel Gautier

    2004-01-01

    We describe an evolutionary turbulent one-dimensional model of the Jovian subnebula, based on the previous models of the solar nebula of Dubrulle (Icarus 106 (1993) 59), and of Drouart et al. (Icarus 140 (1999) 129), as well as on the evolutionary turbulent model of the subnebula of Saturn of Mousis et al. (Icarus 156 (2002a) 162). We show that the

  10. A deterministic electron, photon, proton and heavy ion transport suite for the study of the Jovian moon Europa

    Microsoft Academic Search

    Francis F. Badavi; Steve R. Blattnig; William Atwell; John E. Nealy; Ryan B. Norman

    2011-01-01

    A Langley research center (LaRC) developed deterministic suite of radiation transport codes describing the propagation of electron, photon, proton and heavy ion in condensed media is used to simulate the exposure from the spectral distribution of the aforementioned particles in the Jovian radiation environment. Based on the measurements by the Galileo probe (1995–2003) heavy ion counter (HIC), the choice of

  11. A deterministic electron, photon, proton and heavy ion transport suite for the study of the Jovian moon Europa

    Microsoft Academic Search

    Francis F. Badavi; Steve R. Blattnig; William Atwell; John E. Nealy; Ryan B. Norman

    2011-01-01

    A Langley research center (LaRC) developed deterministic suite of radiation transport codes describing the propagation of electron, photon, proton and heavy ion in condensed media is used to simulate the exposure from the spectral distribution of the aforementioned particles in the Jovian radiation environment. Based on the measurements by the Galileo probe (1995-2003) heavy ion counter (HIC), the choice of

  12. The Microwave Properties of Jovian Clouds: Laboratory Measurement of Aqueous Ammonia (NH4OH) Between 2-8.5 GHz

    NASA Astrophysics Data System (ADS)

    Duong, Danny; Steffes, P. G.

    2010-10-01

    Laboratory measurements of the complex dielectric properties of aqueous ammonia, under conditions characteristic of Jovian clouds, have been made in the 2-8.5 GHz range at temperatures ranging from 24-60 oC and concentrations of 0-8.5% ammonia (NH3) by volume. No previous laboratory experiments have been made to characterize the microwave dielectric properties of aqueous ammonia. Previous models of Jovian microwave emission (de Pater et al., Icarus, 2005) have assumed that for low concentrations of ammonia in solution, the dielectric properties of aqueous ammonia are approximately equal to those of water; however, these measurements suggest that even at concentrations as low as 0.5% NH3 by volume, there is a marked difference in the complex dielectric properties of aqueous ammonia. Assuming Raleigh scattering, these measurements are applied to a cloud attenuation model to calculate the opacity of the Jovian aqueous ammonia clouds. These measurements will improve our understanding of the data collected by the Juno microwave radiometer (MWR) by characterizing the absorption properties of the aqueous ammonia present in the Jovian atmosphere. This work was supported by NASA Contract NNM06AA75C from the Marshall Space Flight Center supporting the Juno Mission Science Team, under Subcontract 699054X from the South-west Research Institute.

  13. The microwave properties of the jovian clouds: A new model for the complex dielectric constant of aqueous ammonia

    NASA Astrophysics Data System (ADS)

    Duong, Danny; Steffes, Paul G.; Noorizadeh, Sahand

    2014-02-01

    A new model for the complex dielectric constant of aqueous ammonia (NH4OH) under conditions characteristic of the jovian clouds has been developed. The new model is based on laboratory measurements in the frequency range between 2 and 8.5 GHz for ammonia concentrations of 0-8.5% by volume and temperatures between 274 and 297 K. The new model is based on the Meissner and Wentz (Meissner, T., Wentz, F.J. [2004]. IEEE Trans. Geosci. Rem. Sens. 42, 1836-1849) model of the complex dielectric constant of pure water but contains corrections for dissolved ammonia. Assuming Raleigh scattering, these measurements are applied to a cloud attenuation model to calculate the range of opacity of the jovian aqueous ammonia clouds. These measurements will improve our understanding of the data collected by the Juno microwave radiometer (MWR) by better characterizing the absorption properties of the aqueous ammonia present in the jovian atmosphere. The new model has been validated for temperatures up to 313 K, and may be consistently used for the expected conditions for aqueous clouds in all of the outer planets. The model fits 60.26% of all laboratory measurements within 2-sigma uncertainty. Descriptions of the experimental setups, uncertainties associated with the laboratory measurements, the model fitting process, the new model, and its application to approximating jovian cloud opacity are provided.

  14. A solitary wave theory of the Great Red SPOT and other observed features in the Jovian atmosphere

    Microsoft Academic Search

    T. Maxworthy; L. G. Redekopp

    1976-01-01

    It is shown that solitary waves in a planetary zonal shear have a shape and flow field that are virtually identical to those observed around the Red Spot and numerous other features that have been seen in the Jovian atmosphere. It is suggested that the theoretically calculated interaction between solitary waves has many characteristics in common with the observed interactions

  15. Initial assessments of ignition spherical torus

    SciTech Connect

    Peng, Y.K.M.; Borowski, S.K.; Bussell, G.T.; Dalton, G.R.; Gorker, G.E.; Haines, J.R.; Hamilton, W.R.; Kalsi, S.S.; Lee, V.D.; Miller, J.B.

    1985-12-01

    Initial assessments of ignition spherical tori suggest that they can be highly cost effective and exceptionally small in unit size. Assuming advanced methods of current drive to ramp up the plasma current (e.g., via lower hybrid wave at modest plasma densities and temperatures), the inductive solenoid can largely be eliminated. Given the uncertainties in plasma energy confinement times and the effects of strong paramagnetism on plasma pressure, and allowing for the possible use of high-strength copper alloys (e.g., C-17510, Cu-Ni-Be alloy), ignition spherical tori with a 50-s burn are estimated to have major radii ranging from 1.0 to 1.6 m, aspect ratios from 1.4 to 1.7, vacuum toroidal fields from 2 to 3 T, plasma currents from 10 to 19 MA, and fusion power from 50 to 300 MW. Because of its modest field strength and simple poloidal field coil configuration, only conventional engineering approaches are needed in the design. A free-standing toroidal field coil/vacuum vessel structure is assessed to be feasible and relatively independent of the shield structure and the poloidal field coils. This exceptionally simple configuration depends significantly, however, on practical fabrication approaches of the center conductor post, about which there is presently little experience. 19 refs.

  16. Determination of ionic abundances in the Io torus using the Hopkins Ultraviolet Telescope

    NASA Technical Reports Server (NTRS)

    Moos, H. W.; Feldman, P. D.; Durrance, S. T.; Blair, W. P.; Bowers, C. W.; Davidsen, A. F.; Dixon, W. V.; Henry, R. C.; Ferguson, H. C.; Kimble, R. A.

    1991-01-01

    Attention is given to a 415-1864-A spectrum of the emissions from the Io torus with about 3-A resolution in first order (830-1864 A) obtained with HUT in December 1990. A list of the 31 strongest features shows that, apart from five features that are totally or partially terrestrial, all are due to O(+), S(+), S(2+), and S(3+). There is no evidence for elements other than oxygen and sulfur. The spectrum shows many additional weaker emission features so that the existence of minor species cannot be ruled out at this time. Because the HUT spectrum contains well-resolved lines for all four of the major species, the mixing ratio (Ni/ne) for each one can be determined without using models of the spectral emissions, or a detailed geometric model of the torus plasma. The relative concentration of O(+) determined from the HUT observation is 38 percent less than that obtained from the Voyager UVS data.

  17. H-mode threshold and dynamics in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Bush, C. E.; Bell, M. G.; Bell, R. E.; Boedo, J.; Fredrickson, E. D.; Kaye, S. M.; Kubota, S.; LeBlanc, B. P.; Maingi, R.; Maqueda, R. J.; Sabbagh, S. A.; Soukhanovskii, V. A.; Stutman, D.; Swain, D. W.; Wilgen, J. B.; Zweben, S. J.; Davis, W. M.; Gates, D. A.; Johnson, D. W.; Kaita, R.; Kugel, H. W.; Lee, K. C.; Mastrovito, D.; Medley, S.; Menard, J. E.; Mueller, D.; Ono, M.; Paoletti, F.; Park, H.; Paul, S. J.; Peng, Y.-K. M.; Raman, R.; Roney, P. G.; Roquemore, A. L.; Skinner, C. H.; Synakowski, E. J.; Taylor, G.

    2003-05-01

    Edge parameters play a critical role in high confinement mode (H-mode) access, which is a key component of discharge optimization in present day toroidal confinement experiments and the design of next generation devices. Because the edge magnetic topology of a spherical torus (ST) differs from a conventional aspect ratio tokamak, H-modes in STs exhibit important differences compared with tokamaks. The dependence of the National Spherical Torus Experiment (NSTX) [C. Neumeyer et al., Fusion Eng. Des. 54, 275 (2001)] edge plasma on heating power, including the low confinement mode (L-mode) to H-mode (L-H) transition requirements and the occurrence of edge-localized modes (ELMs), and on divertor configuration is quantified. Comparisons between good L-modes and H-modes show greater differences in the ion channel than the electron channel. The threshold power for the H-mode transition in NSTX is generally above the predictions of a recent International Tokamak Experimental Reactor (ITER) [ITER Physics Basis Editors, Nucl. Fusion 39, 2175 (1999)] scaling. Correlations of transition and ELM phenomena with turbulent fluctuations revealed by gas puff imaging and reflectometry are observed. In both single-null and double-null divertor discharges, the density peaks off-axis, sometimes developing prominent "ears" which can be sustained for many energy confinement times, ?E, in the absence of ELMs. A wide variety of ELM behavior is observed, and ELM characteristics depend on configuration and fueling.

  18. On a Transition from Solar-Like Coronae to Rotation-Dominated Jovian-Like Magnetospheres in Ultracool Main-Sequence Stars

    NASA Astrophysics Data System (ADS)

    Schrijver, Carolus J.

    2009-07-01

    For main-sequence stars beyond spectral type M5, the characteristics of magnetic activity common to warmer solar-like stars change into the brown-dwarf domain: the surface magnetic field becomes more dipolar and the evolution of the field patterns slows, the photospheric plasma is increasingly neutral and decoupled from the magnetic field, chromospheric and coronal emissions weaken markedly, and the efficiency of rotational braking rapidly decreases. Yet, radio emission persists, and has been argued to be dominated by electron-cyclotron maser emission instead of the gyrosynchrotron emission from warmer stars. These properties may signal a transition in the stellar extended atmosphere. Stars warmer than about M5 have a solar-like corona and wind-sustained heliosphere in which the atmospheric activity is powered by convective motions that move the magnetic field. Stars cooler than early-L, in contrast, may have a Jovian-like rotation-dominated magnetosphere powered by the star's rotation in a scaled-up analog of the magnetospheres of Jupiter and Saturn. A dimensional scaling relationship for rotation-dominated magnetospheres by Fan et al. is consistent with this hypothesis.

  19. ON A TRANSITION FROM SOLAR-LIKE CORONAE TO ROTATION-DOMINATED JOVIAN-LIKE MAGNETOSPHERES IN ULTRACOOL MAIN-SEQUENCE STARS

    SciTech Connect

    Schrijver, Carolus J. [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, CA 94304 (United States)], E-mail: schrijver@lmsal.com

    2009-07-10

    For main-sequence stars beyond spectral type M5, the characteristics of magnetic activity common to warmer solar-like stars change into the brown-dwarf domain: the surface magnetic field becomes more dipolar and the evolution of the field patterns slows, the photospheric plasma is increasingly neutral and decoupled from the magnetic field, chromospheric and coronal emissions weaken markedly, and the efficiency of rotational braking rapidly decreases. Yet, radio emission persists, and has been argued to be dominated by electron-cyclotron maser emission instead of the gyrosynchrotron emission from warmer stars. These properties may signal a transition in the stellar extended atmosphere. Stars warmer than about M5 have a solar-like corona and wind-sustained heliosphere in which the atmospheric activity is powered by convective motions that move the magnetic field. Stars cooler than early-L, in contrast, may have a Jovian-like rotation-dominated magnetosphere powered by the star's rotation in a scaled-up analog of the magnetospheres of Jupiter and Saturn. A dimensional scaling relationship for rotation-dominated magnetospheres by Fan et al. is consistent with this hypothesis.

  20. Physics design of a 28 GHz electron heating system for the National Spherical Torus experiment upgrade

    NASA Astrophysics Data System (ADS)

    Taylor, G.; Bertelli, N.; Ellis, R. A.; Gerhardt, S. P.; Harvey, R. W.; Hosea, J. C.; Poli, F.; Raman, R.; Smirnov, A. P.

    2014-02-01

    A megawatt-level, 28 GHz electron heating system is being designed to support non-inductive (NI) plasma current (Ip) start-up and local heating and current drive (CD) in H-mode discharges in the National Spherical Torus Experiment Upgrade (NSTX-U). The development of fully NI Ip start-up and ramp-up is an important goal of the NSTXU research program. 28 GHz electron cyclotron (EC) heating is predicted to rapidly increase the central electron temperature (Te(0)) of low density NI plasmas generated by Coaxial Helicity Injection (CHI). The increased Te(0) will significantly reduce the Ip decay rate of CHI plasmas, allowing the coupling of fast wave heating and neutral beam injection. Also 28 GHz electron Bernstein wave (EBW) heating and CD can be used during the Ip flat top in NSTX-U discharges when the plasma is overdense. Ray tracing and Fokker-Planck numerical simulation codes have been used to model EC and EBW heating and CD in NSTX-U. This paper presents a pre-conceptual design for the 28 GHz heating system and some of the results from the numerical simulations.

  1. Initial operation of the national spherical torus experiment fast tangential soft x-ray camera

    NASA Astrophysics Data System (ADS)

    Stratton, B. C.; Feder, R.; Goeler, S. von; Renda, G. F.; Mastrocola, V. J.; Lowrance, J. L.

    2004-10-01

    Fast, two-dimensional, soft x-ray imaging is a powerful technique for the study of magnetohydrodynamic instabilities in tokamak plasmas. We have constructed an ultra-fast frame rate soft x-ray camera for the national spherical torus experiment (NSTX). It is based on a recently developed 64×64 pixel charge-coupled device (CCD) camera capable of capturing 300 frames at up to 500 000 frames per second. A pinhole aperture images the plasma soft x-ray emission (0.2-10 keV) onto a P47 scintillator deposited on a fiber-optic faceplate; the scintillator visible light output is detected and amplified by a demagnifying image intensifier and lens-coupled to the CCD chip. A selection of beryllium foils provides discrimination of low-energy emission. The system is installed on NSTX with a wide-angle tangential view of the plasma. Initial plasma data and an assessment of the system performance are presented.

  2. Characterization of Disruption Halo Currents in the National Spherical Torus Experiment

    SciTech Connect

    S.P. Gerhardt, J. Menard, S. Sabbagh and F. Scotti

    2012-04-25

    This paper describes the general characteristics of disruptions halo currents in the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)]. The commonly observed types of vertical motion and resulting halo current patterns are described, and it is shown that plasma discharges developing between components can facilitate halo current flow. The halo current fractions and toroidal peaking factors at various locations in the device are presented. The maximum product of these two metrics for localized halo current measurements is always significantly less than the worst-case expectations from conventional aspect ratio tokamaks (which are typically written in terms of the total halo current). The halo current fraction and impulse is often largest in cases with the fastest plasma current quenches and highest quench rates. The effective duration of the halo current pulse is comparable to or shorter than the plasma current quench time. The largest halo currents have tended to occur in lower ? and lower elongation plasmas. The sign of the poloidal halo current is reversed when the toroidal field direction is reversed.

  3. Studies of improved electron confinement in low density L-mode National Spherical Torus Experiment discharges

    NASA Astrophysics Data System (ADS)

    Stutman, D.; Finkenthal, M.; Tritz, K.; Redi, M. H.; Kaye, S. M.; Bell, M. G.; Bell, R. E.; LeBlanc, B. P.; Hill, K. W.; Medley, S. S.; Menard, J. E.; Rewoldt, G.; Wang, W. X.; Synakowski, E. J.; Levinton, F.; Kubota, S.; Bourdelle, C.; Dorland, W.; The NSTX Team

    2006-09-01

    Electron transport is rapid in most National Spherical Torus Experiment, M. Ono et al., Nucl. Fusion 40, 557 (2000) beam heated plasmas. A regime of improved electron confinement is nevertheless observed in low density L-mode ("low-confinement") discharges heated by early beam injection. Experiments were performed in this regime to study the role of the current profile on thermal transport. Variations in the magnetic shear profile were produced by changing the current ramp rate and onset of neutral beam heating. An increased electron temperature gradient and local minimum in the electron thermal diffusivity were observed at early times in plasmas with the fastest current ramp and earliest beam injection. In addition, an increased ion temperature gradient associated with a region of reduced ion transport is observed at slightly larger radii. Ultrasoft x-ray measurements of double-tearing magnetohydrodynamic activity, together with current diffusion calculations, point to the existence of negative magnetic shear in the core of these plasmas. Discharges with slower current ramp and delayed beam onset, which are estimated to have more monotonic q-profiles, do not exhibit regions of reduced transport. The results are discussed in the light of the initial linear microstability assessment of these plasmas, which suggests that the growth rate of all instabilities, including microtearing modes, can be reduced by negative or low magnetic shear in the temperature gradient region. Several puzzles arising from the present experiments are also highlighted.

  4. BPS states in the Omega-background and torus knots

    E-print Network

    Bulycheva, Ksenia

    2013-01-01

    We clarify some issues concerning the central charges saturated by the extended objects in the SUSY $U(1)$ $4d$ gauge theory in the $\\Omega$-background. The configuration involving the monopole localized at the domain wall is considered in some details. At the rational ratio $\\frac{\\epsilon_1}{\\epsilon_2}=\\frac{p}{q}$ the trajectory of the monopole provides the torus $(p,q)$ knot in the squashed three-sphere. Using the relation between the integrable systems of Calogero type at the rational couplings and the torus knots we interpret this configuration in terms of the auxiliary $2d$ quiver theory or $3d$ theory with nontrivial boundary conditions. This realization can be considered as the AGT-like representation of the torus knot invariants.

  5. Weak integrability of Hamiltonians on the two torus and rigidity

    NASA Astrophysics Data System (ADS)

    Barbosa Gomes, José; Ruggiero, Rafael O.

    2013-07-01

    We show that a C? k-basic Finsler metric on the two torus T2 whose geodesic flow preserves a codimension one C1,L foliation is in fact flat. Although integrable high energy levels of Hamiltonians on the torus are not flat in general, the C1,L integrability of k-basic Finsler geodesic flows on T2 implies flatness and in particular, C? integrability. We also show that a codimension one C1 foliation invariant by the geodesic flow of any Finsler metric on T2 must coincide with the Busemann foliation. A consequence of the above results is that the Hopf conjecture would be false for k-basic Finsler metrics on the two torus if and only if there exists a C0 integrable k-basic Finsler geodesic flow that is not C1,L integrable.

  6. Feasibility study of low angle planetary entry. [probe design for Jovian entry

    NASA Technical Reports Server (NTRS)

    Defrees, R. E.

    1975-01-01

    The feasibility of a Jovian entry by a probe originally designed for Saturn and Uranus entries is examined. An entry probe is described which is capable of release near an outer planet's sphere of influence and descent to a predetermined target entry point in the planet's atmosphere. The probe is designed so as to survive the trapped particle radiation belts and an entry heating pulse. Data is gathered and relayed to an overflying spacecraft bus during descent. Probe variations for two similar missions are described. In the first flyby of Jupiter by a Pioneer spacecraft launched during the 1979 opportunity is examined parametrically. In the second mission an orbiter based on Pioneer and launched in 1980 is defined in specific terms. The differences rest in the science payloads and directly affected wiring and electronics packages.

  7. Planetary protection for an outer planet flagship mission to the jovian system

    NASA Astrophysics Data System (ADS)

    Spry, James A.; Newlin, Laura; Clark, Karla; Lewis, Kari

    The Jupiter Europa Orbiter is an Outer Planet Flagship mission concept currently under study by NASA. In the present mission architecture proposal, a jovian system science tour would precede a phase in a science orbit around Europa, and subsequent deorbit and impact on the Europan surface. Under COSPAR planetary protection policy, such a mission would have the significant require-ment to avoid inadvertent contamination of an Europan ocean to below the 1 x 10-4 probability level. In the current study, PP planning for such a mission is utilizing a range of implementation strategies to meet the probabilistic requirement, including pre-launch bioburden reduction of flight hardware; recontamination prevention; in flight radiation effects; and avoidance of unin-tentional impact at solar system bodies of concern. This presentation will discuss the various strategies currently under consideration.

  8. Magnetic properties of Jupiter's tail at distances from 80-7500 Jovian radii

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Lepping, R. P.; Sittler, E. C., Jr.

    1984-01-01

    A detailed study of the magnetic field data from both Voyagers 1 and 2 has revealed several interesting properties of the near and distant Jovian magnetotail. During the first encounter, as Voyager 1 passed between 80 and 140 R sub J from Jupiter in the near tail, the spacecraft was almost entirely in the northerm lobe magnetic field. The frequency spectrum of magnetic fluctuation in this region cannot be characterized by a power law and does not appear to be turbulent. The distant tail spectra from Voyager 2 are compared with similar spectra obtained from Voyager 1 when it was in near radial alignment with Voyager 2. Although the gross properties of the tail and solar wind fields in most respects differ considerably, the shape and power levels of the spectra of the magnetic fluctuations are very similar, especially between .0001 and .001 Hz. At lower frequencies (.00001 to .0001 Hz) the spectra of magnetic helicity do differ.

  9. The Unified Radio and Plasma wave investigation

    NASA Technical Reports Server (NTRS)

    Stone, R. G.; Bougeret, J. L.; Caldwell, J.; Canu, P.; De Conchy, Y.; Cornilleau-Wehrlin, N.; Desch, M. D.; Fainberg, J.; Goetz, K.; Goldstein, M. L.

    1992-01-01

    The scientific objectives of the Ulysses Unified Radio and Plasma wave (URAP) experiment are twofold: (1) the determination of the direction, angular size, and polarization of radio sources for remote sensing of the heliosphere and the Jovian magnetosphere and (2) the detailed study of local wave phenomena, which determine the transport coefficients of the ambient plasma. A brief discussion of the scientific goals of the experiment is followed by a comprehensive description of the instrument. The URAP sensors consist of a 72.5 m electric field antenna in the spin plane, a 7.5-m electric field monopole along the spin axis of a pair of orthogonal search coil magnetic antennas. The various receivers, designed to encompass specific needs of the investigation, cover the frequency range from dc to 1 MHz. A relaxation sounder provides very accurate electron density measurements. Radio and plasma wave observations are shown to demonstrate the capabilities and limitations of the URAP instruments: radio observations include solar bursts, auroral kilometric radiation, and Jovian bursts; plasma waves include Langmuir waves, ion acousticlike noise, and whistlers.

  10. One year of Galileo dust data from the Jovian system: 1996

    E-print Network

    H. Krüger; E. Grün; A. Graps; D. Bindschadler; S. Dermott; H. Fechtig; B. A. Gustason; D. P. Hamilton; M. S. Hanner; M. Horányi; J. Kissel; B. A. Lindblad; D. Linkert; G. Linkert; I. Mann; J. A. M. McDonnell; G. E. Morfill; C. Planskey; G. Schwehm; R. Srama; H. A. Zook

    2001-07-03

    The dust detector system onboard Galileo records dust impacts in circumjovian space since the spacecraft has been injected into a bound orbit about Jupiter in December 1995. This is the sixth in a series of papers dedicated to presenting Galileo and Ulysses dust data. We present data from the Galileo dust instrument for the period January to December 1996 when the spacecraft completed four orbits about Jupiter (G1, G2, C3 and E4). Data were obtained as high resolution realtime science data or recorded data during a time period of 100 days, or via memory read-outs during the remaining times. Because the data transmission rate of the spacecraft is very low, the complete data set (i. e. all parameters measured by the instrument during impact of a dust particle) for only 2% (5353) of all particles detected could be transmitted to Earth; the other particles were only counted. Together with the data for 2883 particles detected during Galileo's interplanetary cruise and published earlier, complete data of 8236 particles detected by the Galileo dust instrument from 1989 to 1996 are now available. The majority of particles detected are tiny grains (about 10 nm in radius) originating from Jupiter's innermost Galilean moon Io. These grains have been detected throughout the Jovian system and the highest impact rates exceeded $\\rm 100 min^{-1}$. A small number of grains has been detected in the close vicinity of the Galilean moons Europa, Ganymede and Callisto which belong to impact-generated dust clouds formed by (mostly submicrometer sized) ejecta from the surfaces of the moons (Kr\\"uger et al., Nature, 399, 558, 1999). Impacts of submicrometer to micrometer sized grains have been detected thoughout the Jovian system and especially in the region between the Galilean moons.

  11. Jovian Impact Modeling: Impact Angle Variation and Remapping for Later Phases

    NASA Astrophysics Data System (ADS)

    Pond, Jarrad W.; Palotai, C.; Gabriel, T.; Mueller, D. T.; Szabó, N. R.; Chappell, G.; Korycansky, D.; Harrington, J.

    2012-10-01

    We present our latest results built upon our previous numerical simulations of the Shoemaker Levy-9 (SL9) impact event (Palotai et al. 2011 ApJ 731. 3) and of several Jovian impacts that could possibly explain the 2009 bolide (Pond et al. 2012 ApJ 745. 113). There are significant differences between impactor terminal depths and plume development in our SL9 and 2009 impact simulations; thus, we have continued our work by exploring the effect of varying angles of incidence on Jovian impacts. Bolides possessing impact angles ranging from 00.0 to 80.0 degrees are modeled using ZEUS-MP 2 (Hayes et al. 2006 ApJ.SS. 165. 188-228). We investigate how varying the angle of incidence affects the terminal depths of the impactors, plume development, and ejection velocities, in addition to tracking the thermodynamic history of impactor tracer particles. As was explored with the entry of cometary nuclei of SL9 into Jupiter (Korycansky et al. 2006 ApJ 646. 642-652) and in our 2009 simulations, the effects of chaos on these results are investigated as well. We also developed a conservative algorithm for remapping different variable fields onto larger, coarser computational grids, which are needed to investigate wave propagation and the plume flight phase. This algorithm also preserves important impact characteristics, such as expanding impact shocks, during a remapping from one grid to another. Results from our latest simulations will be shown. This research was supported by National Science Foundation Grant AST-1109729 and NASA Planetary Atmospheres Program Grant NNX11AD87G.

  12. Methane absorption coefficients for the jovian planets from laboratory, Huygens, and HST data

    NASA Astrophysics Data System (ADS)

    Karkoschka, Erich; Tomasko, Martin G.

    2010-02-01

    We use 11 data sets of methane transmission measurements within 0.4-5.5 ?m wavelength to model the methane transmission for temperature and pressure conditions in the jovian planets. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methane absorption inside Titan's atmosphere ( Tomasko et al., 2008b, PSS 56, 624), and we provide a refined analysis. The last data set is a set of new Jupiter images by the Hubble Space Telescope to measure atmospheric transmission with Ganymede as the light source. Below 1000 nm wavelength, our resulting methane absorption coefficients are generally close to those by Karkoschka (1998, Icarus 133, 134), but we add descriptions of temperature and pressure dependence. One remaining inconsistency occurs between 882 and 902 nm wavelength where laboratory data predict larger absorptions in the jovian atmospheres than observed. We present possible explanations. Above 1000 nm, our analysis of the Huygens data confirms methane absorption coefficients by Irwin et al. (2006, Icarus 181, 309) at their laboratory temperatures. Huygens data also confirm Irwin's model of extrapolation to Titan's lower pressures. However, their model of extrapolation to Titan's lower temperatures predicts absorption coefficients up to 100 times lower than measured by Huygens. For each of ˜3700 wavelengths, we present a temperature dependence that is consistent with all laboratory data and the Huygens data. Since the Huygens data probe similar temperatures as many observations of Saturn, Uranus, Neptune, and Titan, our methane model will allow more reliable radiative transfer models for their atmospheres.

  13. StorageEfficient, DeadlockFree Packet Routing Algorithms for Torus Networks \\Lambda

    E-print Network

    Gravano, Luis

    Storage­Efficient, Deadlock­Free Packet Routing Algorithms for Torus Networks \\Lambda Robert Cypher­Free Packet Routing in Torus Networks with Minimal Storage'', by R. Cypher and L. Gravano, which appeared

  14. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 99, NO. All, PAGES 21,213-21,224, NOVEMBER 1, 1994 The sourceof Jovian auroral hissobservedby Voyager 1

    E-print Network

    Gurnett, Donald A.

    . A simpleray tracing procedureusingan offset tilted dipole of the Jovian magneticfield is usedto determine perpendicularto the wave normalvector. The angle· of the ray path relative to the magneticfield is given

  15. Quantization of Hall Conductance For Interacting Electrons on a Torus

    E-print Network

    Matthew B. Hastings; Spyridon Michalakis

    2014-12-02

    We consider interacting, charged spins on a torus described by a gapped Hamiltonian with a unique groundstate and conserved local charge. Using quasi-adiabatic evolution of the groundstate around a flux-torus, we prove, without any averaging assumption, that the Hall conductance of the groundstate is quantized in integer multiples of e^2/h, up to exponentially small corrections in the linear size of the system. In addition, we discuss extensions to the fractional quantization case under an additional topological order assumption on the degenerate groundstate subspace.

  16. Observational Evidence of Torus Instability as Trigger Mechanism for Coronal Mass Ejections: The 2011 August 4 Filament Eruption

    NASA Astrophysics Data System (ADS)

    Zuccarello, F. P.; Seaton, D. B.; Mierla, M.; Poedts, S.; Rachmeler, L. A.; Romano, P.; Zuccarello, F.

    2014-04-01

    Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days—even weeks—which suggests that they are often in equilibrium with their environment before disappearing or erupting. Several eruption models have been proposed that aim to reveal what mechanism causes (or triggers) these solar eruptions. Validating these models through observations represents a fundamental step in our understanding of solar eruptions. We present an analysis of the observation of a filament eruption that agrees with the torus instability model. This model predicts that a magnetic flux rope embedded in an ambient field undergoes an eruption when the axis of the flux rope reaches a critical height that depends on the topology of the ambient field. We use the two vantage points of the Solar Dynamics Observatory (SDO) and the Solar TErrestrial RElations Observatory to reconstruct the three-dimensional shape of the filament, to follow its morphological evolution, and to determine its height just before eruption. The magnetograms acquired by SDO/Helioseismic and Magnetic Imager are used to infer the topology of the ambient field and to derive the critical height for the onset of the torus instability. Our analysis shows that the torus instability is the trigger of the eruption. We also find that some pre-eruptive processes, such as magnetic reconnection during the observed flares and flux cancellation at the neutral line, facilitated the eruption by bringing the filament to a region where the magnetic field was more vulnerable to the torus instability.

  17. Design of a dual sensor probe array for internal field measurement in Versatile Experiment Spherical Torus.

    PubMed

    Jeong-hun, Yang; Chung, Kyoung-Jae; An, YoungHwa; Jung, Bong Ki; Jo, Jong Gab; Hwang, Y S

    2012-10-01

    A dual sensor probe array is designed and constructed for internal magnetic field measurement at Versatile Experiment Spherical Torus (VEST) at the Seoul National University. Simultaneous use of Hall sensors and chip inductors allows cross-calibration among the measurements and compensation for each other's weaknesses while their small sizes are expected to cause only mild plasma perturbations. Calibration of the dual sensor probe array, using a Helmholtz coil, shows good sensitivity for the magnetic field measurement of the VEST. Prior to Ohmic start-up, the magnetic field structure inside the vacuum chamber is measured by using the calibrated probe array. The dual sensor probe array is expected to be useful in analyzing the temporal magnetic field structure change during the magnetic reconnection and in reconstruction of the current profile during the discharge of the VEST device. PMID:23126895

  18. Plasmoids Formation During Simulations of Coaxial Helicity Injection in the National Spherical Torus Experiment.

    PubMed

    Ebrahimi, F; Raman, R

    2015-05-22

    The formation of an elongated Sweet-Parker current sheet and a transition to plasmoid instability has for the first time been predicted by simulations in a large-scale toroidal fusion plasma in the absence of any preexisting instability. Plasmoid instability is demonstrated through resistive MHD simulations of transient coaxial helicity injection experiments in the National Spherical Torus Experiment (NSTX). Consistent with the theory, fundamental characteristics of the plasmoid instability, including fast reconnection rate, have been observed in these realistic simulations. Motivated by the simulations, experimental camera images have been revisited and suggest the existence of reconnecting plasmoids in NSTX. Global, system-size plasmoid formation observed here should also have strong implications for astrophysical reconnection, such as rapid eruptive solar events. PMID:26047235

  19. Statistical analysis of variations in impurity ion heating at reconnection events in the Madison Symmetric Torus

    SciTech Connect

    Cartolano, M. S.; Craig, D., E-mail: darren.craig@wheaton.edu [Wheaton College, Wheaton, Illinois 60187 (United States); Den Hartog, D. J.; Kumar, S. T. A.; Nornberg, M. D. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States) [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, Wisconsin 53706 (United States)

    2014-01-15

    The connection between impurity ion heating and other physical processes in the plasma is evaluated by studying variations in the amount of ion heating at reconnection events in the Madison Symmetric Torus (MST). Correlation of the change in ion temperature with individual tearing mode amplitudes indicates that the edge-resonant modes are better predictors for the amount of global ion heating than the core-resonant modes. There is also a strong correlation between ion heating and current profile relaxation. Simultaneous measurements of the ion temperature at different toroidal locations reveal, for the first time, a toroidal asymmetry to the ion heating in MST. These results present challenges for existing heating theories and suggest a stronger connection between edge-resonant tearing modes, current profile relaxation, and ion heating than has been previously thought.

  20. A Spherical Torus Nuclear Fusion Reactor Space Propulsion Vehicle Concept for Fast Interplanetary Travel

    NASA Technical Reports Server (NTRS)

    Williams, Craig H.; Borowski, Stanley K.; Dudzinski, Leonard A.; Juhasz, Albert J.

    1998-01-01

    A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a greater than 5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all ma or systems including payload, central truss, nuclear reactor (including divertor and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, power utilization, and component design.

  1. Progress in the studies of passive heat removal in the next European torus under accident conditions

    SciTech Connect

    Soria, A. (Universidad Politecnica de Madrid (Spain)); Renda, V.; Papa, L. (Commission of the European Communities, Ispra (Italy). Joint Research Centre); Fenoglio, F. (Politecnico di Torino, Turin (Italy))

    1989-12-01

    Within the framework of safety analysis for the next European torus, a decay heat hazards assessment is under way in Ispra. Undercooling accidents (loss-of-coolant and loss-of-flow accidents (LOCAs and LOFAs)) due to pump failure have been investigated assuming an automatic plasma shutdown in both cases. The passive heat removal mechanisms considered include radiation between components and residual cooling by the thermosyphon effect in the main cooling circuits. Conservative thermohydraulic calculations have been made to determine coolant velocity and temperature transients to avoid water boiling int he circuits. Results show that during a LOFA, water boiling can be avoided provided that the water inertia is large enough, and material melting temperatures are not reached during a LOCA.

  2. Plasmoids Formation During Simulations of Coaxial Helicity Injection in the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Raman, R.

    2015-05-01

    The formation of an elongated Sweet-Parker current sheet and a transition to plasmoid instability has for the first time been predicted by simulations in a large-scale toroidal fusion plasma in the absence of any preexisting instability. Plasmoid instability is demonstrated through resistive MHD simulations of transient coaxial helicity injection experiments in the National Spherical Torus Experiment (NSTX). Consistent with the theory, fundamental characteristics of the plasmoid instability, including fast reconnection rate, have been observed in these realistic simulations. Motivated by the simulations, experimental camera images have been revisited and suggest the existence of reconnecting plasmoids in NSTX. Global, system-size plasmoid formation observed here should also have strong implications for astrophysical reconnection, such as rapid eruptive solar events.

  3. Ohmic Flux Consumption During Initial Operation of the NSTX Spherical Torus

    SciTech Connect

    J. Menard; B. LeBlanc; S.A. Sabbagh; M. Bell; R. Bell; E. Fredrickson; D. Gates; S. Jardin; S. Kaye; H. Kugel; R. Maingi; R. Maqueda; D. Mueller; M. Ono; S.Paul; C.H. Skinner; D. Stutman; and the NSTX Research Team.

    2000-10-05

    The spherical tokamak (ST), because of its slender central column, has very limited volt-second capability relative to a standard aspect ratio tokamak of similar plasma cross-section. Recent experiments on the National Spherical Torus Experiment (NSTX) have begun to quantify and optimize the ohmic current drive efficiency in a MA-class ST device. Sustainable ramp-rates in excess of 5MA/sec during the current rise phase have been achieved on NSTX, while faster ramps generate significant MHD activity. Discharges with Ip exceeding 1MA have been achieved in NSTX with nominal parameters: aspect ratio A=1.3--1.4, elongation k=2--2.2, triangularity d=0.4, internal inductance li=0.6, and Ejima coefficient CE=0.35. Flux consumption efficiency results, performance improvements associated with first boronization, and comparisons to neoclassical resistivity are described.

  4. Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment

    SciTech Connect

    S.S. Medley; D.S. Darrow; D. Liu; A.L. Roquemore

    2005-03-25

    Early neutral-beam injection is used in the National Spherical Torus Experiment (NSTX) to heat the electrons and slow current penetration which keeps q(0) elevated to avoid deleterious MHD activity and at the same time reduces Ohmic flux consumption, all of which aids long-pulse operation. However, the low plasma current (I{sub p} {approx} 0.5 MA) and electron density (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}) attending early injection lead to elevated orbit and shine through losses. The inherent orbit losses are aggravated by large excursions in the outer gap width during current ramp-up. An investigation of this behavior using various energetic particle diagnostics on NSTX and TRANSP code analysis is presented.

  5. Magnetospheric Plasma Effects on the Icy Satellites

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Cassidy, T. A.; Hendrix, A. R.; Paranicas, C.; Teolis, B. D.

    2011-12-01

    The effect of magnetospheric plasma bombardment on the icy satellites is reviewed. Suggested effects range from the production and stripping of an atmosphere to modification of the chemistry and thermal properties of the surface. There has been speculation on the role of the incident plasma particles beginning with early ground based observation of leading trailing differences on the icy Jovian satellites through to the recent Cassini discoveries of the leading hemisphere features on Mimas and Tethys and the O2/CO2 atmosphere on Rhea. Here the role of the plasma in removing and producing atmosphere on the icy satellites will be discussed, as well as the physical and chemical effects of the plasma on the surface for the various particle types and energies. The latter will be related to recent observations, which sample the surface over a range of penetration depths.

  6. Density and beta limits in the Madison Symmetric Torus Reversed-Field Pinch

    NASA Astrophysics Data System (ADS)

    Caspary, Kyle Jonathan

    Operational limits and the underlying physics are explored on the Madison Symmetric Torus (MST) Reversed-Field Pinch (RFP) using deuterium pellet fueling. The injection of a fast pellet provides a large source of fuel in the plasma edge upon impact with the vessel wall, capable of triggering density limit terminations for the full range of plasma current, up to 600 kA. As the pellet size and plasma density increase, approaching the empirical Greenwald limit, plasma degradation is observed in the form of current decay, increased magnetic activity in the edge and core, increased radiation and plasma cooling. The complete termination of the plasma is consistent with the Greenwald limit; however, a slightly smaller maximum density is observed in discharges without toroidal field reversal. The plasma beta is the ratio of the plasma pressure to the confining magnetic pressure. Beta limits are known to constrain other magnetic confinement devices, but no beta limit has yet been established on the RFP. On MST, the highest beta values are obtained in improved confinement discharges with pellet fueling. By using pellet injection to scan the plasma density during PPCD, we also achieve a scan of Ohmic input power due to the increase in plasma resistivity. We observe a factor of 3 or more increase in Ohmic power as we increase the density from 1*1019 to 3*10 19 m-3. Despite this increased Ohmic power, the electron contribution to beta is constant, suggesting a confinement limited beta for the RFP. The electrons and ions are classically well coupled in these cold, dense pellet fueled plasmas, so the increase in total beta at higher density is primarily due to the increased ion contribution. The interaction of pellet fueling and NBI heating is explored. Modeling of MST's neutral heating beam suggests an optimal density for beam power deposition of 2-3*1019 m-3. Low current, NBI heated discharges show evidence of an increased electron beta in this density range. Additionally, the fast ion population can enhance ablation as well as cause pellet deflection. Other exploratory experiments with the pellet injection system explore additional injection scenarios and expand the injector capabilities.

  7. GC GYOTO Torus 3+1 Simulating observations of the vicinity of the

    E-print Network

    Gourgoulhon, Eric

    GC GYOTO Torus 3+1 Simulating observations of the vicinity of the galactic center compact object observations of the GC #12;GC GYOTO Torus 3+1 My co-authors Thibaut PAUMARD, Observatoire de Paris/LESIA Eric Simulating observations of the GC #12;GC GYOTO Torus 3+1 Galactic Center at large scale Chandra : size = 1

  8. Fast photodiode diagnostic on Alcator C-Mod tokamak to study the plasma edge/SOL structure

    E-print Network

    Veto?, Ba?lint

    2005-01-01

    The tokamak is so far the most promising magnetic confinement configuration to control fusion scale plasmas and to be a large scale source of electricity in the future. Built in the shape of a torus of major and minor ...

  9. Testing the Twisted Torus Model of Quasar Obscuration

    NASA Astrophysics Data System (ADS)

    Elvis, Martin; Rose, M.; Lawrence, A.; Roseboom, I.

    2014-01-01

    The Unified Scheme of AGNs uses a cold, thick torus to block our view of the nucleus from most directions. This is a theoretically implausible structure, even if clumpy. An alternative structure, which arises naturally in some scenarios for feeding supermassive black holes, is a "twisted torus", a warped thin dusty disk (Lawrence and Elvis 2010). Roseboom et al. (2013) found that this model predicted the correct, wide, distribution of hot dust covering factors for SDSS type 1 (broad-line) quasars (mean ~0.35, sigma ~0.2). Here we report the spectral energy distributions (from tahe WISE, UKIDSS/2MASS, SDSS surveys) for ~200 type 2 SDSS quasars with 0.3 < z < 0.83 from Reyes et al. (2008), with luminosities 8.3 < log L([OIII]) < 10. The twisted torus model predicts a higher average covering factor 0.65) for these objects than for a matched sample of type 1 quasars. We will present our results on this strong test of the twisted torus model.

  10. Optimal Torus Exploration by Oblivious Mobile Robots S. Devismes1

    E-print Network

    Paris-Sud XI, Université de

    Optimal Torus Exploration by Oblivious Mobile Robots S. Devismes1 , A. Lamani2 , F. Petit3 , and S (France) 3 LIP6, UPMC Sorbonne Universit´es (France) Abstract We consider autonomous robots that are endowed with motion actuators and visibility sen- sors. The robots we consider are weak, i

  11. Generalized rational blow-down, torus knots, and Euclidean algorithm

    E-print Network

    Yamada, Yuichi

    2007-01-01

    We construct a Kirby diagram of the rational homology ball used in "generalized rational blow-down" developed by Jongil Park. The diagram consists of a dotted circle and a torus knot. The link is simpler, but the parameters are a little complicate. Euclidean Algorithm is used three times in the construction and the proof.

  12. Bounce precession fishbones in the national spherical torus experiment

    Microsoft Academic Search

    Eric Fredrickson; Liu Chen; Roscoe White

    2003-01-01

    Bursting modes, which are identified as bounce precession frequency fishbone modes, are observed on a low aspect ratio tokamak, the national spherical torus experiment (Ono M. et al 2000 Nucl. Fusion 40 557). They are predicted to be important in high current, low shear discharges with a significant population of trapped particles with a large mean bounce angle, such as

  13. Combinatorial geometries and torus strata on homogeneous compact manifolds

    Microsoft Academic Search

    I. M. Gel'fand; V. V. Serganova

    1987-01-01

    CONTENTSIntroduction § 1. Torus orbits and strata on the Grassmannian § 2. Matroids and strata on the Grassmannian § 3. The moment mapping and toric varieties § 4. The geometry of compact homogeneous spaces § 5. Definition of a stratum via the moment mapping § 6. Strata and Schubert cells § 7. Polytopes corresponding to strata § 8. The general

  14. Preliminary Design of JLAB Clas12 Large Superconducting Torus Magnet

    SciTech Connect

    Wang, B; Taylor, C; Zbasnik, J; Dell& #x27; Orco, D; Ross, J; Chen, J; Xu, L; Chen, H; Wagner, B; McMullin, J; Pong, R; Juang, T; Wang, M; Carter, C; Quettier, L; Burkert, V; Elouadrhiri, L; Kashy, D; Leung, E

    2011-06-01

    Hall B at Jefferson Laboratory (JLAB) will need a 6-coil Torus producing a required integral of B-dl for an upgrade 12 GeV beam. In Sept. 2009, Wang NMR was awarded a contract to design, fabricate, assemble, deliver, and test at JLAB this ex citing magnet. The preliminary design review was completed by Dec. 2009 and intermediate design review will be completed by July 2010. Proto type coil construction, production of soldered conductor with SSC cable and final design review will be completed in 2010. We shall describe preliminary design and intermediate design for coil/cryostat, Torus central cylinder (hub), 48 cold mass suspensions, two intercoil support rings, cryocontrol tower, and adapter to Torus coil, magnet quench protection, and charge/ discharge con trol, and the two parallel path cooling design using supercritical helium. Because of coil in-plane and out-of-plane EM forces over these huge thin coils in addition to vacuum load, gravity load, and cool down thermal stress, we shall present the finite element analyses (FEA) on coil structure, 48 cold mass supports, intercoil cold rings, coil/ cryostat vacuum vessel, cryotower cryostat, and Torus hub. Finally, we shall shows that all pressure/ vacuum vessels and its weldment has satisfied ASME code.

  15. Information Spreading on Almost Torus Networks Antonia Maria Masucci 1

    E-print Network

    the intertwined propagation of two competing "memes" (or viruses, rumors, etc.) in a composite network (individual that the meme persistence and the meme strength on each plane, and the spectral radius of the graph, completely determine which of the two competing "memes" prevail. The topologies of focus in this work, torus

  16. A showcase of torus canards in neuronal bursters

    PubMed Central

    2012-01-01

    Rapid action potential generation - spiking - and alternating intervals of spiking and quiescence - bursting - are two dynamic patterns commonly observed in neuronal activity. In computational models of neuronal systems, the transition from spiking to bursting often exhibits complex bifurcation structure. One type of transition involves the torus canard, which we show arises in a broad array of well-known computational neuronal models with three different classes of bursting dynamics: sub-Hopf/fold cycle bursting, circle/fold cycle bursting, and fold/fold cycle bursting. The essential features that these models share are multiple time scales leading naturally to decomposition into slow and fast systems, a saddle-node of periodic orbits in the fast system, and a torus bifurcation in the full system. We show that the transition from spiking to bursting in each model system is given by an explosion of torus canards. Based on these examples, as well as on emerging theory, we propose that torus canards are a common dynamic phenomenon separating the regimes of spiking and bursting activity. PMID:22657918

  17. Nonlinear MHD simulation of current drive by multi-pulsed coaxial helicity injection in spherical torus

    NASA Astrophysics Data System (ADS)

    Kanki, Takashi; Nagata, Masayoshi; Kagei, Yasuhiro

    2011-10-01

    The dynamics of structures of magnetic field, current density, and plasma flow generated during multi-pulsed coaxial helicity injection in spherical torus is investigated by 3-D nonlinear MHD simulations. During the driven phase, the flux and current amplifications occur due to the merging and magnetic reconnection between the preexisting plasma in the confinement region and the ejected plasma from the gun region involving the n = 1 helical kink distortion of the central open flux column (COFC). Interestingly, the diamagnetic poloidal flow which tends toward the gun region is then observed due to the steep pressure gradients of the COFC generated by ohmic heating through an injection current winding around the inboard field lines, resulting in the formation of the strong poloidal flow shear at the interface between the COFC and the core region. This result is consistent with the flow shear observed in the HIST. During the decay phase, the configuration approaches the axisymmetric MHD equilibrium state without flow because of the dissipation of magnetic fluctuation energy to increase the closed flux surfaces, suggesting the generation of ordered magnetic field structure. The parallel current density ? concentrated in the COFC then diffuses to the core region so as to reduce the gradient in ?, relaxing in the direction of the Taylor state.

  18. Direct X-B mode conversion for high-? national spherical torus experiment in nonlinear regime

    NASA Astrophysics Data System (ADS)

    Ali Asgarian, M.; Parvazian, A.; Abbasi, M.; Verboncoeur, J. P.

    2014-09-01

    Electron Bernstein wave (EBW) can be effective for heating and driving currents in spherical tokamak plasmas. Power can be coupled to EBW via mode conversion of the extraordinary (X) mode wave. The most common and successful approach to study the conditions for optimized mode conversion to EBW was evaluated analytically and numerically using a cold plasma model and an approximate kinetic model. The major drawback in using radio frequency waves was the lack of continuous wave sources at very high frequencies (above the electron plasma frequency), which has been addressed. A future milestone is to approach high power regime, where the nonlinear effects become significant, exceeding the limits of validity for present linear theory. Therefore, one appropriate tool would be particle in cell (PIC) simulation. The PIC method retains most of the nonlinear physics without approximations. In this work, we study the direct X-B mode conversion process stages using PIC method for incident wave frequency f0 = 15 GHz, and maximum amplitude E0 = 105 V/m in the national spherical torus experiment (NSTX). The modelling shows a considerable reduction in X-B mode conversion efficiency, Cmodelling = 0.43, due to the presence of nonlinearities. Comparison of system properties to the linear state reveals predominant nonlinear effects; EBW wavelength and group velocity in comparison with linear regime exhibit an increment around ˜36% and 17%, respectively.

  19. Direct X-B mode conversion for high-? national spherical torus experiment in nonlinear regime

    SciTech Connect

    Ali Asgarian, M., E-mail: maliasgarian@ph.iut.ac.ir, E-mail: maa@msu.edu [Physics Department, Isfahan University of Technology, Isfahan 84156 (Iran, Islamic Republic of); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States); Parvazian, A.; Abbasi, M. [Physics Department, Isfahan University of Technology, Isfahan 84156 (Iran, Islamic Republic of); Verboncoeur, J. P. [Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States)

    2014-09-15

    Electron Bernstein wave (EBW) can be effective for heating and driving currents in spherical tokamak plasmas. Power can be coupled to EBW via mode conversion of the extraordinary (X) mode wave. The most common and successful approach to study the conditions for optimized mode conversion to EBW was evaluated analytically and numerically using a cold plasma model and an approximate kinetic model. The major drawback in using radio frequency waves was the lack of continuous wave sources at very high frequencies (above the electron plasma frequency), which has been addressed. A future milestone is to approach high power regime, where the nonlinear effects become significant, exceeding the limits of validity for present linear theory. Therefore, one appropriate tool would be particle in cell (PIC) simulation. The PIC method retains most of the nonlinear physics without approximations. In this work, we study the direct X-B mode conversion process stages using PIC method for incident wave frequency f{sub 0}?=?15?GHz, and maximum amplitude E{sub 0}?=?10{sup 5?}V/m in the national spherical torus experiment (NSTX). The modelling shows a considerable reduction in X-B mode conversion efficiency, C{sub modelling}?=?0.43, due to the presence of nonlinearities. Comparison of system properties to the linear state reveals predominant nonlinear effects; EBW wavelength and group velocity in comparison with linear regime exhibit an increment around ?36% and 17%, respectively.

  20. Comparison of Poloidal Velocity Meassurements to Neoclassical Theory on the National Spherical Torus Experiment

    SciTech Connect

    Bell, R E; Kaye, S M; Kolesnikov, R A; LeBlance, B P; Rewolldt, G; Wang, W X

    2010-04-07

    Knowledge of poloidal velocity is necessary for the determination of the radial electric field, Er, which along with its gradient is linked to turbulence suppression and transport barrier formation. Recent measurements of poloidal flow on conventional tokamaks have been reported to be an order of magnitude larger than expected from neoclassical theory. In contrast, recent poloidal velocity measurements on the NSTX spherical torus [S. M. Kaye et al., Phys. Plasmas 8, 1977 (2001)] are near or below neoclassical estimates. A novel charge exchange recombination spectroscopy diagnostic is used, which features active and passive sets of up/down symmetric views to produce line-integrated poloidal velocity measurements that do not need atomic physics corrections. Local profiles are obtained with an inversion. Poloidal velocity measurements are compared with neoclassical values computed with the codes NCLASS [W. A. Houlberg et al., Phys. Plasmas 4, 3230 (1997)] and GTC-Neo [W. X. Wang, et al., Phys. Plasmas 13, 082501 (2006)], which has been updated to handle impurities. __________________________________________________

  1. Energy confinement scaling in the low aspect ratio National Spherical Torus Experiment (NSTX)

    NASA Astrophysics Data System (ADS)

    Kaye, S. M.; Bell, M. G.; Bell, R. E.; Fredrickson, E. D.; LeBlanc, B. P.; Lee, K. C.; Lynch, S.; Sabbagh, S. A.

    2006-10-01

    Systematic and statistical studies have been conducted in order to develop an understanding of the parametric dependences of both the global and thermal energy confinement times at low aspect ratio in high power National Spherical Torus Experiment discharges. The global and thermal confinement times of both L- and H-mode discharges can exceed values given by H-mode scalings developed for conventional aspect ratio. Results of systematic scans in the H-mode indicate that the confinement times exhibit a nearly linear dependence on plasma current and a power degradation weaker than that observed at conventional aspect ratio. In addition, the dependence on the toroidal magnetic field is stronger than that seen in conventional aspect ratio tokamaks. This latter trend is also evident in statistical analyses of the available dataset. These statistical studies also indicate a weaker parametric dependence on plasma current than found in the systematic scans, due to correlations among the predictor variables. Regressions based on engineering variables, when transformed to dimensionless physics variables, indicate that the dependence of B?E on ?t can range from being negative to null. Regressions based directly on the dimensionless physics variables are inexact because of large correlations among these variables. Scatter in the confinement data, at otherwise fixed operating parameters, is found to be due to variations in ELM activity, low frequency density fluctuations and plasma shaping.

  2. Parametric excitation of gyroscopic waves in Thomson-Delaney cells of the ocean of Jovian moon Europa

    Microsoft Academic Search

    B. I. Rabinovich

    2011-01-01

    A possible mechanism (of parametric resonance type) of excitation of planetary gyroscopic waves in Thomson-Delaney cells of\\u000a the ocean of Jovian moon Europa is considered. It is assumed that the basis of this mechanism is a variation of liquid depth\\u000a in a cell caused by tidal oscillations under the action of gravitational perturbing influence of Galilean satellites of Jupiter.\\u000a Such

  3. The Microwave Properties of Jovian Clouds: Laboratory Measurement of Aqueous Ammonia (NH4OH) Between 2-8.5GHz

    NASA Astrophysics Data System (ADS)

    Duong, D.; Steffes, P. G.; Noorizadeh, S.

    2011-10-01

    Laboratory measurements of the complex dielectric properties of aqueous ammonia, under conditions characteristic of Jovian clouds, have been made in the 2-8.5GHz range at temperatures ranging from 4- 40oC and concentrations of 0-8.5% NH3 by volume. A model has been developed to characterize the effects of NH3 on the complex dielectric properties relative to water.

  4. Hâ fluorescence spectrum from 1200 to 1700 A by electron impact: Laboratory study and application to Jovian aurora

    Microsoft Academic Search

    Y. L. Yung; G. R. Gladstone; K. M. Chang; J. M. Ajello; S. K. Srivastava

    1982-01-01

    A combined experimental study of the fluorescence spectrum of Hâ at wavelengths of 1200--1700 A by electron impact and its application to modeling the Jovian aurora have been carried out. Our laboratory data suggest that at 100 eV the relative cross sections for direct excitation of Ly..cap alpha.., Lyman bands (B¹..sigma..\\/sup +\\/\\/sub u\\/-X¹..sigma..\\/sup +\\/\\/sub g\\/), and Werner bands (C¹..pi..\\/sub u\\/-X¹..sigma..\\/sup

  5. JANUS: the visible camera onboard the ESA JUICE mission to the Jovian system

    NASA Astrophysics Data System (ADS)

    Palumbo, Pasquale; Jaumann, Ralf; Cremonese, Gabriele; Hoffmann, Harald; Debei, Stefano; Della Corte, Vincenzo; Holland, Andrew; Lara, Luisa Maria

    2014-05-01

    The JUICE (JUpiter ICy moons Explorer) mission [1] was selected in May 2012 as the first Large mission in the frame of the ESA Cosmic Vision 2015-2025 program. JUICE is now in phase A-B1 and its final adoption is planned by late 2014. The mission is aimed at an in-depth characterization of the Jovian system, with an operational phase of about 3.5 years. Main targets for this mission will be Jupiter, its satellites and rings and the complex relations within the system. Main focus will be on the detailed investigation of three of Jupiter's Galilean satellites (Ganymede, Europa, and Callisto), thanks to several fly-bys and 9 months in orbit around Ganymede. JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the camera system selected by ESA to fulfill the optical imaging scientific requirements of JUICE. It is being developed by a consortium involving institutes in Italy, Germany, Spain and UK, supported by respective Space Agencies, with the support of Co-Investigators also from USA, France, Japan and Israel. The Galilean satellites Io, Europa, Ganymede and Callisto show an increase in geologic activity with decreasing distance to Jupiter [e.g., 2]. The three icy Galilean satellites Callisto, Ganymede and Europa show a tremendous diversity of surface features and differ significantly in their specific evolutionary paths. Each of these moons exhibits its own fascinating geologic history - formed by competition and also combination of external and internal processes. Their origins and evolutions are influenced by factors such as density, temperature, composition (volatile compounds), stage of differentiation, volcanism, tectonism, the rheological reaction of ice and salts to stress, tidal effects, and interactions with the Jovian magnetosphere and space. These interactions are still recorded in the present surface geology. The record of geological processes spans from possible cryovolcanism through widespread tectonism to surface degradation and impact cratering. Observation of the Jupiter atmosphere, satellite's exo-spheres, Jupiter ring system, minor satellites and Ganymede rotational status are additional important objec-tives shared with other JUICE instruments. JANUS will allow orders-of-magnitude steps ahead in terms of coverage and/or resolution and/or time evolution on many targets in Jupiter system. JANUS ground sampling ranges from 400 m/pixel to < 3 m/pixel for the three main Galilean satellites, and from few to few tens of km/pixel for Jupiter and the other targets in the Jovian system. Assuming the available scientific data volume (about 20% allocated to JANUS out of 1.4 Gb/day during operations), JANUS observations will cover about 100% of Ganymede in 4 colours at 400 m/pixel. About 3% of the surface of Ganymede will be covered with sampling better than 24 m/pixel and 60 targeted areas will be observed with best sampling of about 3 m/pixel. This will represent a dramatic improvement with respect to Galileo coverage. References: [1] Grasset O. et al. (2013) Planet. and Space Sci 78, 1-21. [2] Stephan K. et al.(2013) The Science of Solar System Ices, M. S. Gutipati and J. Castillo-Rogez editors. Astrophys. and Space Sci. Libr. 356, 279 - 367.

  6. Experimental Investigation of Rotational, Pumping, Magnetic Pumping and Toroidal Asymmetry Modes in a Toroidal Electron Plasma

    NASA Astrophysics Data System (ADS)

    Doares, A. R.; Wang, K.; Patterson, A. S.; Stoneking, M. R.

    2014-10-01

    Electron plasma is confined with a purely toroidal magnetic field in the Lawrence Non-Neutral Torus II (R0 = 18 cm, a ~ 2 cm), for times (~1 s) that are much longer than any of the dynamical timescales of the system. The experiment can be operated as a variable-length partial torus or a full torus trap. The damping rate for the m = 1 diocotron mode in a partial torus trap is found to depend on the equilibrium position (major radius) and on magnetic field (150 G--550 G). We report on efforts to explain these results in terms of rotational and magnetic pumping effects using 3D (Poisson-Boltzmann) equilibria calculations. Novel full torus asymmetry modes are examined with multiple separatrices and a new charge tomography is developed to infer charge density from image charge measurements on the conducting boundary. This work is supported by National Science Foundation Award No. 1202540.

  7. Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H-mode

    SciTech Connect

    Baumgaertel, J. A.; Redi, M. H.; Budny, R. V.; Rewoldt, G.; Dorland, W.

    2005-10-19

    Insight into plasma microturbulence and transport is being sought using linear simulations of drift waves on the National Spherical Torus Experiment (NSTX), following a study of drift wave modes on the Alcator C-Mod Tokamak. Microturbulence is likely generated by instabilities of drift waves, which cause transport of heat and particles. Understanding this transport is important because the containment of heat and particles is required for the achievement of practical nuclear fusion. Microtearing modes may cause high heat transport through high electron thermal conductivity. It is hoped that microtearing will be stable along with good electron transport in the proposed low collisionality International Thermonuclear Experimental Reactor (ITER). Stability of the microtearing mode is investigated for conditions at mid-radius in a high density NSTX high performance (H-mode) plasma, which is compared to the proposed ITER plasmas. The microtearing mode is driven by the electron temperature gradient, and believed to be mediated by ion collisions and magnetic shear. Calculations are based on input files produced by TRXPL following TRANSP (a time-dependent transport analysis code) analysis. The variability of unstable mode growth rates is examined as a function of ion and electron collisionalities using the parallel gyrokinetic computational code GS2. Results show the microtearing mode stability dependence for a range of plasma collisionalities. Computation verifies analytic predictions that higher collisionalities than in the NSTX experiment increase microtearing instability growth rates, but that the modes are stabilized at the highest values. There is a transition of the dominant mode in the collisionality scan to ion temperature gradient character at both high and low collisionalities. The calculations suggest that plasma electron thermal confinement may be greatly improved in the low-collisionality ITER.

  8. The composition of the Jovian atmosphere as determined by the Galileo probe mass spectrometer.

    PubMed

    Niemann, H B; Atreya, S K; Carignan, G R; Donahue, T M; Haberman, J A; Harpold, D N; Hartle, R E; Hunten, D M; Kasprzak, W T; Mahaffy, P R; Owen, T C; Way, S H

    1998-09-25

    The Galileo probe mass spectrometer determined the composition of the Jovian atmosphere for species with masses between 2 and 150 amu from 0.5 to 21.1 bars. This paper presents the results of analysis of some of the constituents detected: H2, He, Ne, Ar, Kr, Xe, CH4, NH3, H2O, H2S, C2 and C3 nonmethane hydrocarbons, and possibly PH3 and Cl. 4He/H2 in the Jovian atmosphere was measured to be 0.157 +/- 0.030. 13C/C12 was found to be 0.0108 +/- 0.0005, and D/H and 3He/4He were measured. Ne was depleted, < or = 0.13 times solar, Ar < or = 1.7 solar, Kr < or = 5 solar, and Xe < or = 5 solar. CH4 has a constant mixing ratio of (2.1 +/- 0.4) x 10(-3) (12C, 2.9 solar), where the mixing ratio is relative to H2. Upper limits to the H2O mixing ratio rose from 8 x 10(-7) at pressures <3.8 bars to (5.6 +/- 2.5) x 10(-5) (16O, 0.033 +/- 0.015 solar) at 11.7 bars and, provisionally, about an order of magnitude larger at 18.7 bars. The mixing ratio of H2S was <10(-6) at pressures less than 3.8 bars but rose from about 0.7 x 10(-5) at 8.7 bars to about 7.7 x 10(-5) (32S, 2.5 solar) above 15 bars. Only very large upper limits to the NH3 mixing ratio have been set at present. If PH3 and Cl were present, their mixing ratios also increased with pressure. Species were detected at mass peaks appropriate for C2 and C3 hydrocarbons. It is not yet clear which of these were atmospheric constituents and which were instrumentally generated. These measurements imply (1) fractionation of 4He, (2) a local, altitude-dependent depletion of condensables, probably because the probe entered the descending arm of a circulation cell, (3) that icy planetesimals made significant contributions to the volatile inventory, and (4) a moderate decrease in D/H but no detectable change in (D + 3He)/H in this part of the galaxy during the past 4.6 Gyr. PMID:11543372

  9. Configuration and Heating Power Dependence of Edge Parameters and H-mode Dynamics in National Spherical Torus Experiment (NSTX)

    SciTech Connect

    C.E. Bush; M.G. Bell; R.E. Bell; J. Boedo; E.D. Fredrickson; S.M. Kaye; S. Kubota; B.P. LeBlanc; R. Maingi; R.J. Maqueda; S.A. Sabbagh; V.A. Soukhanovskii; D. Stutman; D.W. Swain; J.B. Wilgen; S.J. Zweben; W.M. Davis; D.A. Gates; D.W. Johnson; R. Kaita; H.W. Kugel; D. Mastrovito; S. Medley; J.E. Menard; D. Mueller; M. Ono; F. Paoletti; S.J. Paul; Y-K.M. Peng; R. Raman; P.G. Roney; A.L. Roquemore; C.H. Skinner; E.J. Synakowski; G. Taylor; the NSTX Team

    2003-01-09

    Edge parameters play a critical role in H-mode (high-confinement mode) access, which is a key component of plasma discharge optimization in present-day toroidal confinement experiments and the design of next-generation devices. Because the edge magnetic topology of a spherical torus (ST) differs from a conventional aspect ratio tokamak, H-modes in STs exhibit important differences compared with tokamaks. The dependence of the NSTX (National Spherical Torus Experiment) edge plasma on heating power, including the L-H transition requirements and the occurrence of edge-localized modes (ELMs), and on divertor configuration is quantified. Comparisons between good L-modes (low-confinement modes) and H-modes show greater differences in the ion channel than the electron channel. The threshold power for the H-mode transition in NSTX is generally above the predictions of a recent ITER (International Thermonuclear Experimental Reactor) scaling. Correlations of transition and ELM phenomena with turbulent fluctuations revealed by Gas Puff Imaging (GPI) and reflectometry are observed. In both single-null and double-null divertor discharges, the density peaks off-axis, sometimes developing prominent ''ears'' which can be sustained for many energy confinement times, tau subscript ''E'', in the absence of ELMs. A wide variety of ELM behavior is observed, and ELM characteristics depend on configuration and fueling.

  10. Energetic Charged-Particle Phenomena in the Jovian Magnetosphere: First Results from the Ulysses COSPIN Collaboration.

    PubMed

    Simpson, J A; Anglin, J D; Balogh, A; Burrows, J R; Cowley, S W; Ferrando, P; Heber, B; Hynds, R J; Kunow, H; Marsden, R G; McKibben, R B; Müller-Mellin, R; Page, D E; Raviart, A; Sanderson, T R; Staines, K; Wenzel, K P; Wilson, M D; Zhang, M

    1992-09-11

    The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes ( approximately 37 degrees south) on the dusk side and reached higher magnetic latitudes ( approximately 49 degrees north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of approximately 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include (i) an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium, (ii) high-energy electron bursts (rise times approximately 17 megaelectron volts) on the dusk side that are apparently associated with field-aligned currents and radio burst emissions, (iii) persistence of the global 10-hour relativistic electron "clock" phenomenon throughout Jupiter's magnetosphere, (iv) on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail, and (v) consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons. PMID:17776166

  11. A deterministic electrons and protons transport suite for the study of the Jovian system

    NASA Astrophysics Data System (ADS)

    Badavi, Francis; Nealy, John; Norman, Ryan

    Langley Research Center (LaRC) developed deterministic suite of transport codes for describing the transport of electrons, photons and protons in condensed media is used to simulate the effects and exposures from spectral distributions typical of electrons and protons trapped in planetary magnetic fields. The suite is made of a coupled electrons/ photons deterministic transport procedure (CEPTRN) and a light/heavy ions deterministic transport procedure (HZETRN). The primary purpose for the development of the transport suite is to provide a means for rapidly forming numerous repetitive calculations essential for electrons/protons radiation exposure assessments of complex space structures. Several favorable comparisons have been made with statistically oriented Monte Carlo calculations for typical space environment spectra which have indicated that the transport accuracy has not been compromised at the expense of computational speed. For this presentation the radiation environments of the Galilean satellites Io, Europa, Ganymede and Callisto are used as representative boundary conditions to show the capabilities of the transport suite. The Jovian radiation environment is simulated using the Jet Propulsion Lab. (JPL) GIRE model of 2003. For a limited number of candidate shielding materials, the GIRE produced electrons/protons environments are used as boundary condition to the CEPTRN and HZETRN transport suite to evaluate the particle flux and dose due to electrons and protons at various distances from the planet as a function of latitude, longitude, and altitude.

  12. Detection of the 'continuous' H3(+) electrojet in the Jovian Aurora

    NASA Astrophysics Data System (ADS)

    Stallard, T. S.; Miller, S.; Achilleos, N.; Rego, D.; Prange, R.; Dougherty, M.; Joseph, R. D.

    1999-09-01

    Recently we have published the first detection of an auroral electrojet - a fast ion wind circulating around the auroral oval - on Jupiter (Rego et al., Nature, 399, 121-123). The detection was made during an unusual "auroral event", but raised the possibility that such electrojets might be detectable under "normal" auroral conditions. This work, currently in progress, is directed towards that aim. To accomplish this, high resolution infrared spectra and images of the Jovian aurora were taken on the nights of September 7-11(th) 1998, observing the nu_ {2} Q(1,0(-) ) line of H(+}_{3) at 3.953 mu m. The slit was aligned across the planet, perpendicular to the rotational axis, and the spectra were taken at 1 arcsec steps across the planet through the region of aurora. Each spectrum has been fitted row by row with a gaussian using height, width, background and central position as free parameters. This results in a measurement of how the relative central position varies across each spectra. Having processed the data, removing any systematic array effects, rotation, and instrumentally based spatial effects, we intend to show a measurable electrojet from the dopler shift it causes. This will be in the form of LOS maps of the auroral region at different CML taken over the 5 night observation period.

  13. Vetting Kepler Planet Candidates in the Sub-Jovian Desert with Multi-Band Photometry

    E-print Network

    Colón, Knicole D; Ford, Eric B

    2015-01-01

    We present new multi-band transit photometry of three small (R$_{p}$ planet candidates acquired with the Gran Telescopio Canarias. These observations supplement the results presented in Col\\'on & Ford (2011) and Col\\'on et al. (2012), where we used multicolor transit photometry of five Kepler planet candidates to search for wavelength-dependent transit depths and either validate planet candidates or identify eclipsing binary false positives within our sample. In those previous studies, we provided evidence that three targets were false positives and two targets were planets. Here, we present observations that provide evidence supporting a planetary nature for KOI 439.01 and KOI 732.01, and we find that KOI 531.01, a 6 R$_{\\oplus}$ planet candidate around an M dwarf, is likely a false positive. We also present a discussion of the purported "sub-Jovian desert" in the orbital period-planet radius plane, which cannot be easily explained by observationa...

  14. Effects of precursor heating on radiative and chemically reacting viscous flow around a Jovian entry body

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Szema, K. Y.

    1979-01-01

    The influence of change in the precursor region flow properties on the entire shock layer flow phenomena around a Jovian entry body was investigated. The flow in the shock layer was assumed to be steady, axisymmetric, and viscous. Both the chemical equilibrium and the nonequilibrium composition of the shock layer gas were considered. The effects of transitional range behavior were included in the analysis of high altitude entry conditions. Realistic thermophysical and radiation models were used, and results were obtained by employing the implicit finite difference technique in the shock layer and an iterative procedure for the entire shock layer precursor zone. Results obtained for a 45 degree angle hyperboloid blunt body entering Jupiter's atmosphere at zero angle of attack indicates that preheating the gas significantly increases the static pressure and temperature ahead of the shock for entry velocities exceeding 36 km/sec. The nonequilibrium radiative heating rate to the body is found to be significantly higher than the corresponding equilibrium heating. The precursor heating generally increases the radiative and convective heating of a body. That increase is slightly higher for the nonequilibrium conditions.

  15. Influence of nonequilibrium radiation and shape change on aerothermal environment of a Jovian entry body

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Subramanian, S. V.

    1981-01-01

    The influence of nonequilibrium radiative energy transfer and the effect of probe configuration changes on the flow phenomena around a Jovian entry body are investigated. The radiating shock layer flow is assumed to be axisymmetric, viscous, laminar and in chemical equilibrium. The radiative transfer equations are derived under nonequilibrium conditions which include multilevel energy transitions. The equilibrium radiative transfer analysis is performed with an existing nongray radiation model which accounts for molecular band, atomic line, and continuum transitions. The nonequilibrium results are obtained with and without ablation injection in the shock layer. The nonequilibrium results are found to be greatly influenced by the temperature distribution in the shock layer. In the absence of ablative products, the convective and radiative heating to the entry body are reduced under nonequilibrium conditions. The influence of nonequilibrium is found to be greater at higher entry altitudes. With coupled ablation and carbon phenolic injection, 16 chemical species are used in the ablation layer for radiation absorption. Equilibrium and nonequilibrium results are compared under peak heating conditions.

  16. A NEAR-INFRARED SEARCH FOR SILICATES IN JOVIAN TROJAN ASTEROIDS

    SciTech Connect

    Yang Bin [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Jewitt, David, E-mail: yangbin@ifa.hawaii.edu, E-mail: jewitt@ucla.edu [Department of Earth and Space Sciences, Institute for Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095 (United States)

    2011-03-15

    We obtained near-infrared (NIR; 0.8-2.5 {mu}m) spectra of seven Jovian Trojan asteroids that have been formerly reported to show silicate-like absorption features near 1 {mu}m. Our sample includes the Trojan (1172) Aneas, which is one of the three Trojans known to possess a comet-like 10 {mu}m emission feature, indicative of fine-grained silicates. Our observations show that all seven Trojans appear featureless in high signal-to-noise ratio spectra. The simultaneous absence of the 1 {mu}m band and the presence of the 10 {mu}m emission can be understood if the silicates on (1172) Aneas are iron-poor. In addition, we present NIR observations of five optically gray Trojans, including three objects from the collisionally produced Eurybates family. The five gray Trojans appear featureless in the NIR with no diagnostic absorption features. The NIR spectrum of Eurybates can be best fitted with the spectrum of a CM2 carbonaceous chondrite, which hints that the C-type Eurybates family members may have experienced aqueous alteration.

  17. Lyman alpha line shapes from electron impact H2 dissociative processes in the Jovian auroral zone

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr.; Gladstone, G. R.

    1992-01-01

    Over the past two years several Lyman alpha line profile spectra of Jupiter were obtained using the International Ultraviolet Explorer (IUE) telescope. Several different regions of the planet were observed including the auroral zone, the low and mid latitudes, and the equatorial region which includes the Lyman alpha bulge region. These results have presented a very interesting picture of atomic hydrogen on Jupiter with explanations that range from ion outflow in the auroral zone to large thermospheric winds at low and mid latitudes. New data are needed to address the outstanding questions. Almost certainly, high resolution spectra from the Hubble Space Telescope will play a role in new observations. Better data also require better models, and better models require new laboratory data as inputs. The purpose of this program is two-fold: (1) to introduce a method by which new laboratory electron impact measurements of H2 dissociation can be used to calculate both the slow and fast H(S-2) and H(P-2) fragments in an H2 atmosphere; and (2) to determine the predicted Lyman alpha line shape that would result from electron impact production of these dissociative fragments in the Jovian auroral zone.

  18. (abstract) Line Mixing Behavior of Hydrogen-Broadened Ammonia Under Jovian Atmospheric Conditions

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas R.

    1994-01-01

    Laboratory spectral data reported last year have been used to investigate the line mixing behavior of hydrogen-broadened ammonia inversion lines. The data show that broadening parameters appearing in the modified Ben-Reuven opacity formalism of Berge and Gulkis (1976) cannot maintain constant values over pressure ranges that include low to moderate pressures and high pressures. Also, they cannot change drastically in value, as in the Spilker (1990) revision of the Berge and Gulkis formalism. It has long been recognized that at low pressures, less than about 1 bar of a Jovian atmospheric mixture, a VVW formalism yields more accurate predictions of ammonia opacity than Ben-Reuven formalisms. At higher pressures the Ben-Reuven formalisms are more accurate. Since the Ben-Reuven lineshape collapses to a VVW lineshape in the low pressure limit, this low pressure inaccuracy of the Ben-Reuven formalisms is surprising. By incorporating various behavior, a new formalism is produced that is more accurate than previous formalisms, particularly in the critical 'transition region' from 0.5 to 2 bars, and that can be used without discontinuity from pressures of zero to hundreds of bars. The new formalism will be useful in such applications as interpretation of radio astronomical and radio occultation data on giant planet atmospheres, and radiative transfer modeling of those atmospheres.

  19. Temporal Behavior of Ammonia and Temperature in the Jovian Stratosphere following the SL9 Impacts

    NASA Technical Reports Server (NTRS)

    Kostiuk, Ttheodor; Fast, K.; Livengood, T.; Buhl, D.; Espenak, F.; Romani, P.; Betz, A.; Boreiko, R.

    1999-01-01

    We will present new results in the study of temporal changes in ammonia (NH3) abundance, altitude distribution, and temperature in the stratosphere of Jupiter after the Comet Shoemaker-Levy 9 impact in 1994. Data obtained by Betz et al. (1994) using infrared heterodyne spectroscopy were analyzed using a newly developed beam integration radiative transfer code. The spectra are from six different impact regions and were acquired from hours to three weeks following the impact. The data consist of single NH3 stratospheric emission line profiles near 10 microns measured at a resolving power of approximately 10(exp 7). The true line profiles and the new radiative transfer program permitted the simultaneous retrieval of information on both the NH3 abundance and thermal structure as well as to set constraints on the altitude distribution of stratospheric ammonia. Retrieved column densities varied from approximately 10(exp 18) to 10(exp 16) over the three week period. Over the same time period the altitude of the emitting region varied from levels above the few mbar pressure region to below the 50 mbar pressure regions. Stratospheric temperatures hours after impact were approximately 220 K and about 8 days after impact returned to the quiescent levels (approximately 170-180 K). Results from this self-consistent set of measurements will be presented, compared to those from other measurements, and compared to theoretical retrievals from photochemical models for NH3 in the Jovian stratosphere.

  20. Beta Deformation and Superpolynomials of (n,m) Torus Knots

    E-print Network

    Shakirov, Shamil

    2011-01-01

    Recent studies in several interrelated areas - from combinatorics and representation theory in mathematics to quantum field theory and topological string theory in physics - have independently revealed that many classical objects in these fields admit a relatively novel one-parameter deformation. This deformation, known in different contexts under the names of Omega-background, refinement, or beta-deformation, has a number of interesting mathematical implications. In particular, in knot theory beta-deformation transforms the classical HOMFLY invariants into Dunfield-Gukov-Rasmussen superpolynomials - Poincare polynomials of a triply graded knot homology theory. In this paper we give an explicit formula for these superpolynomials in the case of (n,m) torus knots. This new formula generalizes the earlier rezult of arXiv:1106.4305 on (n, nk + 1) torus knots, bringing to light a hidden integrability-like structure.

  1. Recent results from the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Maingi, R.; Bell, M. G.; Bell, R. E.; Bialek, J.; Bourdelle, C.; Bush, C. E.; Darrow, D. S.; Fredrickson, E. D.; Gates, D. A.; Gilmore, M.; Gray, T.; Jarboe, T. R.; Johnson, D. W.; Kaita, R.; Kaye, S. M.; Kubota, S.; Kugel, H. W.; LeBlanc, B. P.; Maqueda, R. J.; Mastrovito, D.; Medley, S. S.; Menard, J. E.; Mueller, D.; Nelson, B. A.; Ono, M.; Paoletti, F.; Park, H. K.; Paul, S. F.; Peebles, T.; Peng, Y.-K. M.; Phillips, C. K.; Raman, R.; Rosenberg, A. L.; Roquemore, A. L.; Ryan, P. M.; Sabbagh, S. A.; Skinner, C. H.; Soukhanovskii, V. A.; Stutman, D.; Swain, D. W.; Synakowski, E. J.; Taylor, G.; Wilgen, J.; Wilson, J. R.; Wurden, G. A.; Zweben, S. J.; NSTX Team

    2003-05-01

    The National Spherical Torus Experiment (NSTX) is a low aspect-ratio fusion research facility whose research goal is to make a determination of the attractiveness of the spherical torus concept in the areas of high-beta stability, confinement, current drive, and divertor physics. Remarkable progress was made in extending the operational regime of the device in FY 2002. In brief, betat of 34% and betaN of 6.5 were achieved. H-mode became the main operational regime, and energy confinement exceeded conventional aspect-ratio tokamak scalings. Heating was demonstrated with the radiofrequency antenna, and signatures of current drive were observed. Current initiation with coaxial helicity injection produced discharges of 400 kA, and first measurements of divertor heat flux profiles in H-mode were made.

  2. Experimental demonstration of compact torus compression and acceleration

    Microsoft Academic Search

    James H. Hammer; James L. Eddleman; Charles W. Hartman; Harry S. McLean; Arthur W. Molvik

    1991-01-01

    Tests of compact torus (CT) compression on the RACE device (Phys. Rev. Lett. {bold 61}, 2843 (1988)) have successfully demonstrated stable compression by a factor of 2 in radius, field amplification by factors of 2--3 to 20 kG, and compressed densities exceeding 10¹⁶ cm⁻³. The results are in good agreement with two-dimensional magnetohydrodynamic simulations of the CT dynamics. The CT

  3. Experimental demonstration of compact torus compression and acceleration

    Microsoft Academic Search

    James H. Hammer; James L. Eddleman; Charles W. Hartman; Harry S. McLean; Arthur W. Molvik

    1991-01-01

    Tests of compact torus (CT) compression on the RACE device [Phys. Rev. Lett. 61, 2843 (1988)] have successfully demonstrated stable compression by a factor of 2 in radius, field amplification by factors of 2–3 to 20 kG, and compressed densities exceeding 1016 cm?3. The results are in good agreement with two-dimensional magnetohydrodynamic simulations of the CT dynamics. The CT is

  4. Fusion-reactor aspects of the compact torus

    Microsoft Academic Search

    Hartman

    1981-01-01

    This paper summarizes several studies of fusion reactors based on the compact torus (CT). A wide variety of reactor configurations can be projected within present understanding of the possible types of CT and their macroscopic stability and confinement properties. Three types of CT are considered here, the field-reversed-configuration having B\\/sub Toroidal\\/ = 0, the Spheromak with B\\/sub T\\/ not equal

  5. Gauge Fields on Torus and Partition Function of Strings

    E-print Network

    Atsushi Nakamula; Kiyoshi Shiraishi

    2014-09-24

    In this paper we consider the interrelation between compactified string theories on torus and gauge fields on it. We start from open string theories with background gauge fields and derive partition functions by path integral. Since the effects of background fields and compactification correlate only through string zero modes, we investigate these zero modes. From this point of view, we discuss the Wilson loop mechanism at finite temperature. For the closed string, only a few comments are mentioned.

  6. High energy density fusing using the Compact Torus

    SciTech Connect

    Hartman, C.W.

    1989-02-15

    My remarks are concerned with employing the Compact Torus magnetic field configuration to produce fusion energy. In particular, I would like to consider high energy density regimes where the pressures generated extend well beyond the strength of materials. Under such conditions, where nearby walls are vaporized and pushed aside each shot, the technological constraints are very different from usual magnetic fusion and may admit opportunities for an improved fusion reactor design. 5 refs., 3 figs.

  7. Initial physics results from the National Spherical Torus Experiment

    Microsoft Academic Search

    S. M. Kaye; M. G. Bell; R. E. Bell; J. Bialek; T. Bigelow; M. Bitter; P. Bonoli; D. Darrow; P. Efthimion; J. Ferron; E. Fredrickson; D. Gates; L. Grisham; J. Hosea; D. Johnson; R. Kaita; S. Kubota; H. Kugel; B. Leblanc; R. Maingi; J. Manickam; T. K. Mau; R. J. Maqueda; E. Mazzucato; J. Menard; D. Mueller; B. Nelson; N. Nishino; M. Ono; F. Paoletti; S. Paul; Y.-K. M. Peng; C. K. Phillips; R. Raman; P. Ryan; S. A. Sabbagh; M. Schaffer; C. H. Skinner; D. Stutman; D. Swain; E. Synakowski; Y. Takase; J. Wilgen; J. R. Wilson; W. Zhu; S. Zweben; A. Bers; M. Carter; B. Deng; C. Domier; E. Doyle; M. Finkenthal; K. Hill; T. Jarboe; S. Jardin; H. Ji; L. Lao; K. C. Lee; N. Luhmann; R. Majeski; S. Medley; T. Peebles; R. I. Pinsker; G. Porter; A. Ram; M. Rensink; T. Rognlien; D. Stotler; B. Stratton; G. Taylor; W. Wampler; G. A. Wurden; X. Q. Xu; L. Zeng

    2001-01-01

    The mission of the National Spherical Torus Experiment (NSTX) is to extend the understanding of toroidal physics to low aspect ratio (R\\/a~=1.25) in low collisionality regimes. NSTX is designed to operate with up to 6 MW of high harmonic fast wave (HHFW) heating and current drive, 5 MW of neutral beam injection (NBI) and co-axial helicity injection (CHI) for noninductive

  8. Bumpy torus transport in the low collision frequency limit

    SciTech Connect

    Hazeltine, R.D.; Catto, P.J.

    1980-05-01

    A variational formulation of transport for a closed field line, large aspect ratio bumpy torus in the low collision frequency limit is presented. The relatively large radial excursions made by those particles with canceling magnetic and electric poloidal drifts requires generalization of previous neoclassical techniques. General expressions for the transport coefficients of both charge species are given. Explicit numerical coefficients are evaluated under certain simplifying assumptions for both the banana and non-banana species.

  9. Fast-ion Energy Loss During TAE Avalanches in the National Spherical Torus Experiment

    SciTech Connect

    Fredrickson, E D; Darrow, D S; Gorelenkov, N N; Kramer, G J; Kubota, S; Podesta, M; White, R B; Bortolon, A; Gerhardt, S P; Bell, R E; Diallo, A; LeBlanc, B; Levinton, F M

    2012-07-11

    Strong TAE avalanches on NSTX, the National Spherical Torus Experiment [M. Ono, et al., Nucl. Fusion 40 (2000) 557] are typically correlated with drops in the neutron rate in the range of 5% - 15%. In previous studies of avalanches in L-mode plasmas, these neutron drops were found to be consistent with modeled losses of fast ions. Here we expand the study to TAE avalanches in NSTX H-mode plasmas with improved analysis techniques. At the measured TAE mode amplitudes, simulations with the ORBIT code predict that fast ion losses are negligible. However, the simulations predict that the TAE scatter the fast ions in energy, resulting in a small (? 6%) drop in fast ion ?. The net decrease in energy of the fast ions is sufficient to account for the bulk of the drop in neutron rate, even in the absence of fast ion losses. This loss of energy from the fast ion population is comparable to the estimated energy lost by damping from the Alfven wave during the burst. The previously studied TAE avalanches in L-mode are re-evaluated using an improved calculation of the potential fluctuations in the ORBIT code.

  10. Mon. Not. R. Astron. Soc. 377, 13931406 (2007) doi:10.1111/j.1365-2966.2007.11687.x The properties of Jovian Trojan asteroids listed in SDSS Moving Object

    E-print Network

    Iveziæ, ?eljko

    2007-01-01

    of Jovian Trojan asteroids listed in SDSS Moving Object Catalogue 3 Gy. M. Szab´o,1 Z. Ivezi´c,2 M. Juri´c3 candidate Jovian Trojan asteroids listed in the 3rd release of the Sloan Digital Sky Survey (SDSS) Moving results on a firmer statistical footing. We find that there are significantly more asteroids

  11. Neutral beam excitation of Alfven continua in the madison symmetric torus reversed field pinch

    NASA Astrophysics Data System (ADS)

    Koliner, Jonathan Jay

    Alfven continua and Alfven eigenmodes (AEs) have been generated for reversed-field pinch (RFP) plasma equilibria in Madison Symmetric Torus (MST). Data gathered from the extensive suite of diagnostics on MST was used to generate equilibria using MSTFIT and VMEC. Three dimensional equilibria for spontaneous helical states were generated using the equilibrium reconstruction code V3FIT. The reduced-MHD codes AE3D and STELLGAP were run on all generated equilibria to calculate the continua and AEs. All continuum solutions contain a toroidicity-induced Alfven gap at 200-400 kHz, within which AE solutions appear by coupling of m=0,1 at medium n. The first observation of beam-driven instabilities on the RFP was performed using MST magnetics during neutral beam injection (NBI). Spatially coherent bursts with n=5,m=1 were observed in plasmas with edge safety factor q_a=0. The bursts oscillate at 65 kHz, and reach maximum amplitude and decay away within 100 mus. These bursts persist for the duration of NBI. Secondary n=-1 and n=4 bursts are coupled in time, reaching maximum amplitude with 50 mus after the n=5 peak amplitude. While the n=5 bursts scale weakly with the electron density n_e and strongly with the beam velocity v_beam, the n=4 bursts scale with the Alfven speed v_A. The burst frequencies are well below those of the calculated AEs and the modes are driven even with v_ beam < v_A, suggesting that the bursting modes are EPMs exciting continuum resonances. Burst characteristics were examined in a variety of plasmas. In reversed plasmas, the temporally changing q profile changes the burst resonances, bringing n=6 into resonance halfway through the sawtooth cycle. The n=5 mode switches from its frequency in non-reversed plasmas to a higher frequency at the end of the sawtooth cycle. In deeply reversed plasmas, the bursts are weaker and display chirping behavior as the plasma reversal increases. During the transition to a helical state, the bursts increase in frequency as q on-axis changes, altering the parallel wavenumber k_||. When the helical state is established, the bursts terminate.

  12. Progress towards steady state at low aspect ratio on the National Spherical Torus Experiment (NSTX)

    NASA Astrophysics Data System (ADS)

    Gates, D. A.; Menard, J.; Maingi, R.; Kaye, S.; Sabbagh, S. A.; Diem, S.; Wilson, J. R.; Bell, M. G.; Bell, R. E.; Ferron, J.; Fredrickson, E. D.; Kessel, C. E.; LeBlanc, B. P.; Levinton, F.; Manickam, J.; Mueller, D.; Raman, R.; Stevenson, T.; Stutman, D.; Taylor, G.; Tritz, K.; Yu, H.; NSTX Research Team

    2007-09-01

    Modifications to the plasma control capabilities and poloidal field coils of the National Spherical Torus Experiment (NSTX) have enabled a significant enhancement in shaping capability which has led to the transient achievement of a record shape factor (S ? q95 (Ip/a Bt)) of ~41 (MA m-1 T-1) simultaneous with a record plasma elongation of ? ? b/a ~ 3. This result was obtained using isoflux control and real-time equilibrium reconstruction. Achieving high shape factor together with tolerable divertor loading is an important result for future ST burning plasma experiments as exemplified by studies for future ST reactor concepts, as well as neutron producing devices, which rely on achieving high shape factors in order to achieve steady state operation while maintaining MHD stability. Statistical evidence is presented which demonstrates the expected correlation between increased shaping and improved plasma performance. Plasmas with high shape factor have been sustained for pulse lengths which correspond to ?pulse = 1.6s ~ 50 ?E ~ 5 ?CR, where ?CR is the current relaxation time and ?E is the energy confinement time. Plasmas with higher ?t ~ 20% have been sustained for ?pulse = 1.2s ~ 25 ?E ~ 3 ?CR with non-inductive current fractions fNI ~ 50%, with ~40% pressure driven current and ~10% neutral beam driven current. An interesting feature of these discharges is the observation that the central value of the safety factor q(0) remains elevated and constant for several current diffusion times without sawteeth, similar to the 'hybrid mode'. Calculations of the profiles of inductive and non-inductive current are compared with measurements of the total current profile and are shown to be in quantitative agreement. Results are shown from experiments which investigate the applicability of high harmonic fast waves (HHFWs) and electron Bernstein waves (EBWs) as current drive and heating sources, and the possibility of LHCD for future ST devices is raised. A calculated scenario which provides 100% non-inductive current drive is described. NSTX operates with peak divertor heat fluxes which are in the same range as those expected for the ITER device, i.e. with P_{heat_{\\max}} \\sim 10\\,MW\\,m^{-2} . High triangularity, high elongation plasmas on NSTX have been demonstrated to have reduced peak heat flux to the divertor plates to <3 MW m-2.

  13. Solenoid-free Plasma Start-up in NSTX using Transient CHI

    SciTech Connect

    Raman, R.; Nelson, B. A.; Mueller, D.; Jarboe, T. R.; Bell, M. G.; LeBlanc, B.; Maqueda, R.; Menard, J.; Ono, M.; Nagata, M.; Roquemore, L.; Soukhanovskii, V.

    2008-11-03

    Experiments in NSTX have now unambiguously demonstrated the coupling of toroidal plasmas produced by the technique of CHI to inductive sustainment and ramp-up of the toroidal plasma current. This is an important step because an alternate method for plasma startup is essential for developing a fusion reactor based on the spherical torus concept. Elimination of the central solenoid would also allow greater flexibility in the choice of the aspect ratio in tokamak designs now being considered. The transient CHI method for spherical torus startup was originally developed on the HIT-II experiment at the University of Washington.

  14. Jovian Mid-Infrared Aurora: Retrospective Analysis of Variability and Cassini Flyby Measurements in Preparation for Juno

    NASA Astrophysics Data System (ADS)

    Kostiuk, Theodor; Hewagama, Tilak; Livengood, Timothy A.; Fast, Kelly E.; Carlson, Ronald; MacDowall, Robert; Jennings, Donald E.; Pitts, Rebecca

    2014-11-01

    With the approaching arrival of the Juno mission at Jupiter it is important to look at the current knowledge of Jovian phenomena that can or cannot be further studied from orbital spacecraft. It is also important to retrospectively investigate previously acquired data using current improved methods and capabilities. The thermal (mid-) infrared aurora from Jupiter’s polar regions has been studied extensively from ground-based observatories as well as by Voyager IRIS and Cassini CIRS during Jupiter flybys. We report on a reexamination and re-analysis of hydrocarbon emission spectra from the polar regions of Jupiter obtained using ground based infrared heterodyne spectroscopy (IRHS) and Cassini CIRS Fourier transform spectroscopy (FTS) during the flyby of Jupiter in 2000-2001. Measurements with IRHS have been made over 30 years, primarily of ethane near 12 micrometer wavelength. IRHS provides fully resolved individual spectral lines whose shape yields unique information on variability of temperature and abundance. CIRS data, at lower spectral resolution, explores extended spatial distributions and covers a broad spectral region that includes auroral response of ethane as well as several other hydrocarbons in the 8-13 micrometer wavelength region (methane, ethylene, and acetylene). These spectra are radiometrically calibrated and can serve as a sensitive thermometer of the Jovian atmosphere. Recently improved analysis techniques show detailed spatial enhancements of the primary hydrocarbons in northern latitudes. Temporal changes of the ethane line emission over three solar cycles and comparison of retrievals from ethane data taken contemporaneously during the Cassini flyby by both techniques will be compared and results discussed. Juno does not have instrumentation in this spectral region and this work provides complementary information and diagnostics for studying Jovian aurora and magnetosphere in a spectral region and altitude range not directly probed by Juno.

  15. Life detection strategy for Jovian's icy moons: Lessons from subglacial Lake Vostok exploration

    NASA Astrophysics Data System (ADS)

    Bulat, Sergey; Alekhina, Irina; Marie, Dominique; Petit, Jean-Robert

    2010-05-01

    The objective was to estimate the microbial content of accretion ice originating from the subglacial Lake Vostok buried beneath 4-km thick East Antarctic ice sheet with the ultimate goal to discover microbial life in this extreme icy environment. The DNA study constrained by Ancient DNA research criteria was used as a main approach. The flow cytometry was implemented in cell enumerating. As a result, both approaches showed that the accretion ice contains the very low unevenly distributed biomass indicating that the water body should also be hosting a highly sparse life. Up to now, the only accretion ice featured by mica-clay sediments presence allowed the recovery a pair of bacterial phylotypes. This unexpectedly included the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus and one more unclassified phylotype both passing numerous contaminant controls. In contrast, the deeper and cleaner accretion ice with no sediments presence and near detection limit gas content gave no reliable signals. Thus, the results obtained testify that the search for life in the Lake Vostok is constrained by a high chance of forward-contamination. The subglacial Lake Vostok seems to represent the only extremely clean giant aquatic system on the Earth providing a unique test area for searching for life on icy worlds. The life detection strategy for (sub)glacial environments elsewhere (e.g., Jovian's Europa) should be based on stringent decontamination procedures in clean-room facilities, establishment of on-site contaminant library, implementation of appropriate methods to reach detection level for signal as low as possible, verification of findings through ecological settings of a given environment and repetition at an independent laboratory within the specialized laboratory network.

  16. Probing Jovian decametric emission with the long wavelength array station 1

    NASA Astrophysics Data System (ADS)

    Clarke, T. E.; Higgins, C. A.; Skarda, Jinhie; Imai, Kazumasa; Imai, Masafumi; Reyes, Francisco; Thieman, Jim; Jaeger, Ted; Schmitt, Henrique; Dalal, Nagini Paravastu; Dowell, Jayce; Ellingson, S. W.; Hicks, Brian; Schinzel, Frank; Taylor, G. B.

    2014-12-01

    New observations of Jupiter's decametric radio emissions have been made with the Long Wavelength Array Station 1 (LWA1), which is capable of making high-quality observations as low as 11 MHz. Full Stokes parameters were determined for bandwidths of 16 MHz. Here we present the first LWA1 results for the study of six Io-related events at temporal resolutions as fine as 0.25 ms. LWA1 data show excellent spectral detail in Jovian DAM such as simultaneous left-hand circular (LHC) and right-hand circular (RHC) polarized Io-related arcs and source envelopes, modulation lane features, S-burst structures, narrow band N events, and interactions between S bursts and N events. The sensitivity of the LWA1 combined with the low-radio-frequency interference environment allow us to trace the start of the LHC Io-C source region to much earlier CMLIII than typically found in the literature. We find that the Io-C starts as early as CMLIII = 230° at frequencies near 11 MHz. This early start of the Io-C emission may be valuable for refining models of the emission mechanism. We also detect modulation lane structures that appear continuous across LHC and RHC emissions, suggesting that both polarizations may originate from the same hemisphere of Jupiter. We present a study of rare S bursts detected during an Io-D event and show that drift rates are consistent with those from other Io-related sources. Finally, S-N burst events are seen in high spectral and temporal resolution and our data strongly support the cospatial origins of these events.

  17. Spatially resolved UV spectra of Io's Prometheus Plume and anti-Jovian hemisphere

    NASA Astrophysics Data System (ADS)

    Jessup, K. L.; Spencer, J.; Ballester, G. E.; Yelle, R.; Roessler, F.; Howell, R.

    2002-09-01

    We present the highest spatial resolution UV spectroscopy of Io's atmosphere yet obtained. Observing Io's anti-jovian hemisphere with the 0.1" wide slit of the HST Space Telescope Imaging Spectrograph (STIS), the G230L grating and the NUV-MAMA centered on the Prometheus plume, we covered latitudes from 60 N to 60 S including the volcanos Zamama, Malik, Tupan, and Chaac, as well as SO2 frost plains. We will report the SO and SO2 column densities and SO2 gas temperatures observed in each region. Surprisingly, there is only a modest difference in SO2 column abundance between the Prometheus plume and nearby low-latitude SO2 frost plains. Additionally, continuum emission is observed over the Prometheus plume and neighboring low latitude regions near 2800 Å. Preliminary analysis indicates that the intensity of these emissions is consistent with that reported by Geissler et al. (1999) for the emissions,assumed to be continuum emission from SO2, observed over the Prometheus plume by Galileo at 4100 Å. Our model for SO2 gas absorption is based on the most recent SO2 absorption cross-section data. This includes the high resolution (5-7 mA FWHM) Rufus et al. (2001) data taken at 159 K which extends from 1980 to 2200 A, and the 295 K Stark et al. (1999) and Smith et al. (2001) data which has the same resolution as the former and extends from 1980 to 3200 A. The low resolution (0.5 A) 200 K Wu et al. (2000) data which extends from 1980 to 2970 A is also utilized. This model represents the most accurate model of the SO2 gas absorption cross-section possible within the limits of the available SO2 laboratory data.

  18. Jovian Tropospheric Photohemistry: Constraints from Recent Cassini and Galileo Observations and from Laboratory Experiment Simulations

    NASA Astrophysics Data System (ADS)

    Moses, Julianne I.; Sperier, A. D.; Keane, T. C.

    2008-09-01

    We use the Caltech/JPL KINETICS code (Allen et al. 1981, JGR 86, 3617) to develop 1-D (in altitude) photochemical models for Jupiter's troposphere that are consistent with available Cassini, Galileo, Voyager, and Earth-based observations of ammonia and phosphine, and upper limits for HCN. As a test of the adopted chemical reaction list, we simulate laboratory experiments of coupled NH3-PH3 and NH3-C2H2 photochemistry (Ferris et al. 1984, J. Am. Chem. Soc. 106, 318; Ferris and Ishikawa 1988, J. Am. Chem. Soc. 110, 4306; Keane et al. 1996, Icarus 122, 205). We find that the vertical profile of PH3 is sensitive to the assumed tropospheric eddy diffusion coefficient and aerosol extinction, both of which are loosely constrained by observations and seem to vary with latitude. The NH3 profile is controlled by condensation and is relatively insensitive to the eddy diffusion coefficient. As was determined by previous photochemical models, the dominant products of Jovian tropospheric chemistry are P2H4, N2H4, red phosphorus, NH2PH2, and N2. All of these species except N2 will condense. Diphosphine (P2H4) is an underappreciated condensate that will likely be more important than N2H4 as an aerosol component on Jupiter as well as Saturn. Little is known about the chemistry and properties of NH2PH2, but this product could also be an important condensable constituent. Coupled NH3-C2H2 photochemistry does not readily occur in Jupiter's troposphere due to the low predicted (and observed) tropospheric C2H2 abundance. The models therefore produce only a small amount of HCN (well within upper limits), and even smaller amounts of the nitriles, hydrazones, and other organo-nitrogen molecules identified in the laboratory experiments mentioned above. This work was supported by the NASA Planetary Atmospheres Program (NNX08AF05G) and the Lunar and Planetary Institute/USRA.

  19. Fast and slow frequency-drifting millisecond bursts in Jovian decametric radio emissions

    NASA Astrophysics Data System (ADS)

    Ryabov, V. B.; Zarka, P.; Hess, S.; Konovalenko, A.; Litvinenko, G.; Zakharenko, V.; Shevchenko, V. A.; Cecconi, B.

    2014-08-01

    We present an analysis of several Jovian Io-related decametric radio storms recorded in 2004-2012 at the Ukrainian array UTR-2 using the new generation of baseband digital receivers. Continuous baseband sampling within sessions lasting for several hours enabled us to study the evolution of multiscale spectral patterns during the whole storm at varying time and frequency resolutions and trace the temporal transformation of burst structures in unprecedented detail. In addition to the well-known frequency drifting millisecond patterns known as S bursts we detected two other classes of events that often look like S bursts at low resolution but reveal a more complicated structure in high resolution dynamic spectra. The emissions of the first type (LS bursts, superposition of L and S type emissions) have a much lower frequency drift rate than the usual quasi linearly drifting S bursts (QS) and often occur within a frequency band where L emission is simultaneously present, suggesting that both LS and at least part of L emissions may come from the same source. The bursts of the second type (modulated S bursts called MS) are formed by a wideband frequency-modulated envelope that can mimic S bursts with very steep negative (or even positive) drift rates. Observed with insufficient time-frequency resolution, MS look like S bursts with complex shapes and varying drifts; MS patterns often occur in association with (i) narrowband emission; (ii) S burst trains; or (iii) sequences of fast drift shadow events. We propose a phenomenological description for various types of S emissions, that should include at least three components: high- and low-frequency limitation of the overall frequency band of the emission, fast frequency modulation of emission structures within this band, and emergence of elementary S burst substructures, that we call "forking" structures. All together, these three components can produce most of the observed spectral structures, including S bursts with apparently very complex time-frequency structures.

  20. The Plasma Wave Environment of Europa

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.; Persoon, A. M.; Roux, A.; Bolton, S. J.; Alexander, C. J.

    2001-01-01

    The Galileo spacecraft has executed nine close flybys of Jupiter's moon Europa for which plasma wave observations were obtained. This paper presents an analysis of the observations from these flybys taking into consideration the variable geometry of the trajectories in an attempt to characterize the general plasma-wave environment associated with the interaction of the Jovian magnetosphere with the moon. A wide variety of plasma-wave phenomena are found to be associated with this interaction. While there are apparently temporal variations which complicate the analysis, a crude model of the distribution of these phenomena around Europa is derived. Primarily on the upstream side of Europa, and working inward to the moon, electron-cyclotron harmonics are first observed, followed by a region within about two Europa radii of the moon with whistler-mode hiss or chorus, and culminating in a region closest to the moon where a band at the upper hybrid resonance frequency is sometimes enhanced over its ambient intensity. The wake region is approximately two Europa radii across and comprises a broadband, highly variable, and bursty electrostatic phenomenon. Upon closer inspection, these bursty emissions appear as solitary structures similar to those in Earth's auroral zone and plasma sheet boundary layer. In addition to the survey of wave phenomena in the vicinity of Europa, we provide density profiles derived primarily from the upper hybrid resonance frequency which is readily apparent throughout most of each of the flybys. Finally, we suggest that the whistler mode, electron cyclotron harmonic, and upper hybrid resonance emissions are driven by some combination of factors including variations in the magnetic field near Europa and the loss and production of plasma at Europa as a result of the interaction of the Jovian magnetosphere with the moon. By analogy with studies of the ion and electron holes and broadband electrostatic noise at Earth and Jupiter, we argue that the electrostatic solitary structures in the wake are associated with currents and beams coupling Europa to Jupiter's ionosphere.