bluuebunny/crossref_metadata_2025 huggingface dataset:
NF‐κB activation mechanism of 4‐hydroxyhexenal via NIK/IKK and p38 MAPK pathway
Authors: Je Jeong Hwan , Lee Ji Young , Jung Kyung Jin , Sung Bokyung , Go Eun Kyung , Yu Byung Pal , Chung Hae Young
Published: April 2004

4‐Hydroxyhexenal (HHE) is known to affect redox balance during aging, included are vascular dysfunctions. To better understand vascular abnormality through the molecular alterations resulting from HHE accumulation in aging processes, we set out to determine whether up‐regulation of mitogen‐activated protein kinase (MAPK) by HHE is mediated through nuclear factor kappa B (NF‐κB) activation in endothelial cells. HHE induced NF‐κB activation by inhibitor of κB (IκB) phosphorylation via the IκB kinase (IKK)/NF‐κB inducing kinase (NIK) pathway. HHE increased the activity of p38 MAPK and extracellular signal regulated kinase (ERK), but not c‐jun NH2‐terminal kinase, indicating that p38 MAPK and ERK are closely involved in HHE‐induced NF‐κB transactivation. Pretreatment with ERK inhibitor PD98059, and p38 MAPK inhibitor SB203580, attenuated the induction of p65 translocation, IκB phosphorylation, and NF‐κB luciferase activity. These findings strongly suggest that HHE induces NF‐κB activation through IKK/NIK pathway and/or p38 MAPK and ERK activation associated with oxidative stress in endothelial cells.
Value structure at an early age
Authors: Bubeck Maike , Bilsky Wolfgang
Published: April 2004

Research with adult subjects has provided evidence for the validity of Schwartz’ (1992) theory on the structure of values. However, information about children and adolescents is scarce. Using the Portrait Values Questionnaire (PVQ-29) to test the applicability of Schwartz’ values theory to this population, a sample of 1555 German subjects aged 10 to 17 was investigated. Value structure was analyzed for the whole sample and for different age groups. Results broadly confirm the validity of Schwartz’ theory. They do not show the hypothesized correspondence between age and structural complexity, as operationalized by the number of distinct value types. Rather, the value structure of 10 to 12 year olds is nearly as differentiated as that of 15 to 17 year olds.
Semiannual NO2 plumes during the monsoon transition periods over the central Indian Ocean
Authors: Kunhikrishnan T. , Lawrence Mark G. , von Kuhlmann Rolf , Richter Andreas , Ladstätter‐Weißenmayer Annette , Burrows John P.
Published: April 2004

In this study we identify recurring plumes of tropospheric NO2 originating from Africa and Indonesia during the monsoon transition periods over the central Indian Ocean (CIO, 5°N–30°S, 55°E–95°E), based on GOME satellite observations and global model (MATCH‐MPIC) simulations. Despite the relatively short lifetime of NOx, these strong plumes can develop due to the pronounced anti‐cyclonic circulation over the CIO, and the weak maritime convection, which limits vertical mixing. Model results indicate that the plumes are mainly transported in the middle troposphere (MT). Thus, the CIO in the Southern Hemisphere (SH) is not always as pristine as found in INDOEX during the winter monsoon.
Nearly monochromatic waves in the distant tail of the Earth
Authors: Kellogg Paul J. , Bale Stuart D.
Published: April 2004

The Waves experiment on the Wind satellite has been used to survey the occurrence of nearly monochromatic waves in the Earth's tail region. Several hundred examples of monochromatic waves were observed during excursions into the tail, including 218 examples during a 4‐day passage of the Wind satellite through the geotail at −90 RE. We present an investigation of the characteristics of these waves and of the environment in which they are found. The waves are electrostatic, and the distribution of the angle E to B shows peaks at 0° and 90°. The waves near 90° sometimes show electron cyclotron harmonics, but these are very rare in the waves near 0°. It seems that the waves occur most commonly in or near the plasma sheet boundary layer, and it is probable that they are convected downstream from reconnecting regions.
Lithospheric structure of the Yukon, northern Canadian Cordillera, obtained from magnetotelluric data
Authors: Ledo Juanjo , Jones Alan G. , Ferguson Ian J. , Wolynec Lisa
Published: April 2004

Two goals of Lithoprobe's geoscientific studies in the Phanerozoic accretionary cordillera of western North America were to define the subsurface geometries of the terranes and to infer the physical conditions of the crust. These questions were addressed in Canada's southern cordillera a decade ago and have more recently been addressed in the northern cordillera, of which one component of the new studies is magnetotelluric (MT) profiling from ancestral North American rocks to the coast. We present a resistivity cross section, and its interpretation, of the northern cordillera derived from modeling data from 42 MT sites along a 470‐km‐long NE‐SW profile. Beneath the Coast Belt (southwestern end of the profile) a deep crustal low‐resistivity layer dips inland; we interpret the crustal part of this conductor as being due to metasedimentary rocks emplaced and metamorphosed during Paleocene Kula plate subduction. A strong lateral transition in lithospheric mantle resistivity exists below the Intermontane Belt that is spatially coincident with changes in chemical and isotopic characteristics of Tertiary to recent alkaline lavas, suggesting that isotopically enriched lithosphere related to the Coast Belt basalts extends partly beneath the Intermontane Belt. The unusually high lower crustal resistivity in the Intermontane and Omineca Belts, similar in value to the resistivity found in the unextended part of central British Columbia, excludes the presence of fluids or conducting metasediments. Finally, our resistivity model displays strong lateral variation of the middle and lower crust between different terranes within the same belt, as a result of the complex structural evolution of the lithosphere.
Gulf Stream variability during marine isotope stage 3
Authors: Vautravers Maryline J. , Shackleton Nick J. , Lopez‐Martinez Constancia , Grimalt Joan O.
Published: April 2004

We have studied Ocean Drilling Program Site 1060 on the Blake Outer Ridge, which lies beneath the Gulf Stream. We focus on marine isotope stage 3, 60–25 thousand years before present (ka). Sea surface temperatures (SSTs) inferred both from foraminiferal fauna and alkenone ratios, as well as counts of iceberg melt‐out debris and benthic stable isotope analyses, enable our record to be interpreted in terms of regional hydrographic changes as well as changing thermohaline circulation (THC). The observed SST record is consistent with the air temperature record from the Greenland ice cores. However, Site 1060 exhibits important differences in detail compared with the ice core record, and when compared to other sites within the North Atlantic, significant longitudinal differences emerge. At Site 1060 in the western Atlantic, all Greenland stadials (GS) whether associated with Heinrich events (HEs) or not, show a similar small amplitude of cooling; mean faunal‐based SSTaug during GS is only 1.5°C colder than during Greenland interstadials (GIS). In addition, during GS the coldest SSTs are limited to apparently brief events. This is in contrast to several eastern Atlantic sites where HE stadials exhibit coolings that are enhanced by 2°C compared to other GS and where cold conditions are not restricted to cold pulses but cover 2 ka‐long intervals. Furthermore, Site 1060 SSTs remained warm right through each interstadial, in contrast to the sustained and uniform cooling trend through interstadials that is consistently observed in Greenland, indicated by measurements of δ18O in ice.
Economic efficiency and cost implications of habitat conservation: An example in the context of the Edwards Aquifer region
Authors: Gillig Dhazn , McCarl Bruce A. , Jones Lonnie L. , Boadu Frederick
Published: April 2004

Groundwater management in the Edwards Aquifer in Texas is in the process of moving away from a traditional right of capture economic regime toward a more environmentally sensitive scheme designed to preserve endangered species habitats. This study explores economic and environmental implications of proposed groundwater management and water development strategies under a proposed regional Habitat Conservation Plan. Results show that enhancing the habitat by augmenting water flow costs $109–1427 per acre‐foot and that regional water development would be accelerated by the more extreme possibilities under the Habitat Conservation Plan. The findings also indicate that a water market would improve regional welfare and lower water development but worsen environmental attributes.
Stratospheric ozone profiles from Mauna Kea, Hawai'i (19.8°N, 155.5°W) using infrared heterodyne spectroscopy, 1988–2003
Authors: Fast Kelly E. , Kostiuk Theodor , Espenak Fred , Livengood Timothy A. , Hewagama Tilak , A'Hearn Michael F.
Published: April 2004

We present stratospheric ozone abundance profiles retrieved from absorption spectroscopy of the atmosphere backlit by thermal continuum emission of the Moon. Infrared heterodyne spectra at 9.6 μm at a resolving power of λ/Δλ ≥ 106 have been acquired on many occasions between 1988 and 2003 from the NASA Infrared Telescope Facility on Mauna Kea, Hawai'i. IR heterodyne spectroscopy provides a passive probe of terrestrial ozone distribution in the 25–50 km region of the stratosphere with the potential to retrieve altitude‐resolved profiles of temperature and abundance. Retrieved ozone profiles are compared with those obtained nearby using active and in situ means (lidar, ozonesonde) with good agreement (≤0.1 ppmv) in the lower stratosphere and with differences ranging from 0 to 1 ppmv in the upper stratosphere.
Randomisierte, plazebokontrollierte klinische Doppelblindstudie zur Wirksamkeit und Verträglichkeit der oralen Therapie mit Methantheliniumbromid (Vagantin®) bei fokaler Hyperhidrose
Authors: Hund Martina , Sinkgraven Ronald , Rzany Berthold
Published: April 2004

Hintergrund: Methantheliniumbromid (Vagantin®) ist ein quarternäres Ammoniumderivat mit anticholinerger Wirkung, das seit 1951 als orales Therapeutikum bei fokaler Hyperhidrose eingesetzt wird. Daten zur Wirksamkeit und Sicherheit lagen bisher nur in Form von Fallberichten und Fallserien vor. Wir berichten über die Ergebnisse der ersten randomisierten klinisch plazebokontrollierten Doppelblindstudie zur Wirksamkeit und Sicherheit dieses Präparates.

Patienten/Material und Methoden: Insgesamt wurden 41 Patienten (davon 31 (76 %) weiblich) mit einem mittleren Alter (± Standardabweichung) von 28 ± 9,8 Jahren (Spannweite 18,7 – 54,8) in die Studie eingeschlossen. Voraussetzung für einen Studieneinschluß waren eine seit mindestens einem Jahr bestehende fokale Hyperhidrose der Achseln und/oder der Hände und deren gravimetrisch gemessene Schweißproduktion von mindestens 50 mg/min. Die Patienten erhielten täglich über 4 Wochen 2 × 50 mg Methantheliniumbromid bzw. Plazebo p. o. Zur Kontrolle des Therapieeffektes wurde zum einen die Schweißproduktion vor und unter Therapie bestimmt sowie die subjektive Zufriedenheit der Patienten mit der Therapie erfragt.

Ergebnisse: Der Nachweis der Wirksamkeit gelang vor allem für Patienten mit gravimetrisch gesicherter axillärer Hyperhidrose von ≥ 50 mg pro min vor Therapie. Hier fanden sich unter Therapie deutliche Unterschiede zwischen Verum und Plazebo (p = 0,02, χ2‐Test, zweiseitig).

Für die Gesamtgruppe zeigte sich für den Bereich der Achseln eine signifikante Verminderung der gravimetrischen Schweißproduktion in der Verumgruppe von 89,2 ± 73,4 mg/min vor Therapie auf 53,3 ± 48,7 mg/min unter Therapie (p = 0,02, Wilcoxon‐Test, zweiseitig), wohingegen in der Plazebogruppe die Meßwerte mit 60,7 ± 42,8 mg/min vor Therapie und 59,1 ± 40,6 mg/min unter Therapie nahezu unverändert blieben (p = 0,92, Wilcoxon‐Test, zweiseitig). Im Bereich der Hände konnten keine Unterschiede zwischen der Verum‐ und der Plazebogruppe gefunden werden.

Während der gesamten Studiendauer traten keine schwerwiegenden unerwünschten Ereignisse auf. Einzige signifikante Nebenwirkung war die in der Verumgruppe zu erwartende Mundtrockenheit als bekannte Nebenwirkung oraler Anticholinergika.

Diskussion: Methantheliniumbromid wird seit Jahren in der Behandlung der fokalen Hyperhidrose verwendet. Bisher lagen zur Wirksamkeit und Sicherheit jedoch keine größeren Studien vor. In dieser Arbeit konnte erstmals in einer klinischen Studie eine Verminderung der Schweißproduktion im Bereich der Achseln bei guter Verträglichkeit nachgewiesen werden. Die Therapie der fokalen axillären Hyperhidrose mit Methantheliniumbromid 2 × 50 mg/d p. o. kann deshalb empfohlen werden. Vor allem in den Fällen, in denen eine alleinige Lokaltherapie mit z. B. Aluminiumchloridhexahydratlösung sich als wenig wirksam erweist. Im Bereich der Hände konnte keine klinisch relevante Wirkung nachgewiesen werden.
On the generation of mean fields by small-scale electron magnetohydrodynamic turbulence
Authors: Lakhin V. P. , Schep T. J.
Published: April 2004

The problem of the generation of mean magnetic fields by small-scale turbulence within the framework of electron magnetohydrodynamics (EMHD) is considered. Two EMHD models are investigated, a two and one-half dimensional (212D) model in which the magnetic field has all three spatial components but, due to a strong external field, depends only on two coordinates, and a fully three-dimensional (3D) model with an imposed stationary and homogeneous magnetic field. It is shown that in the case of 212D turbulence two possible mechanisms are responsible for the generation of mean magnetic fields. The first one is similar to the α-effect in the MHD dynamo problem and is due to a nonzero helicity of the turbulence. The second one is related to the anisotropy of the turbulence, which can give rise to negative dissipation (resistivity, viscosity) of the mean field. The influence of electron inertia on the above effects is analyzed. Inertia results in a qualitative modification of the helicity effects and may lead to a change in sign of the turbulent viscosity. The criteria for the generation of mean magnetic fields are obtained. In the case of the 3D model, the generation of large-scale helicons by the small-scale helicon turbulence is studied within the framework of the adiabatic approximation. A closed set of equations for the evolution of both the magnetic field of the large-scale helicon and of the generalized action of the small-scale turbulence is obtained. The criterion for the resonant instability of a large-scale helicon due to its interaction with small-scale helicon turbulence is obtained.
Guiding center drift atoms
Authors: Kuzmin S. G. , O’Neil T. M. , Glinsky M. E.
Published: April 2004

Very weakly bound electron-ion pairs in a strong magnetic field are called guiding center drift atoms, since the electron dynamics can be treated by guiding center drift theory. Over a wide range of weak binding, the coupled electron-ion dynamics for these systems is integrable. This paper discusses the dynamics, including the important cross magnetic field motion of an atom as a whole, in terms of the system constants of the motion. Since the dynamics is quasi-classical, quantum numbers are assigned using the Bohr–Sommerfeld rules. Antimatter versions of these guiding center drift atoms likely have been produced in recent experiments.
Rayleigh instability in Hall thrusters
Authors: Litvak Andrei A. , Fisch Nathaniel J.
Published: April 2004

Gradient-driven Rayleigh-type instabilities in Hall plasma thrusters are analyzed using linearized two-fluid hydrodynamic equations. Necessary instability conditions and a general criterion for stability of azimuthally propagating perturbations are derived. For a simplified model of the axial distribution of parameters inside the thruster channel, the growth rate of an unstable wave, resonant with the azimuthal electron flow, is obtained. The frequency and phase relations are related to the results of experimental investigations of high-frequency oscillations in Hall thrusters.
Bifurcation of generic metastable tearing modes interacting with resonant magnetic fields
Authors: Coelho R. , Lazzaro E.
Published: April 2004

The response of generic metastable tearing modes (of which neoclassical tearing modes—NTMs—are a particular example) to resonant external magnetic fields, in rotating tokamak fusion plasmas, is analyzed. In particular, the problem of the bifurcation process that may arise during the driven destabilization of the mode by the external fields is addressed. The results presented provide a clear picture of both the mode amplitude and frequency dynamics in a scenario where there is a differential rotation between the rotating plasma and the external fields. It is shown that the mode frequency exhibits a highly oscillatory behavior during the bifurcation process (owing to the differential rotation) and not a smooth transition between the driving frequency and natural mode rotation. On such grounds, the interpretation of experimental results where magnetic coupling is thought to play a role on the destabilization of some NTMs is revised.
Streaming instabilities driven by mildly relativistic proton beams in plasmas
Authors: Dieckmann M. E. , Eliasson B. , Shukla P. K.
Published: April 2004

The interaction between relativistic ion beams, electrostatic waves and particles in plasmas is studied numerically. This beam-particle interaction is important for the acceleration of electrons above the threshold, where they can perform Fermi acceleration across shocks perpendicular to the magnetic field direction. The electrons form Bernstein–Greene–Kruskal (BGK) modes, which are unstable due to a sideband instability. This process heats the electrons to relativistic temperatures and the electrons finally attain a flat-top momentum distribution with exponentially decreasing tails of the momentum distribution function. A scaling law, depending on the ion beam speed, is found for the electron distribution function. Furthermore, in the fully nonlinear phase, ion phase space vortices, or proton BGK modes are formed in the beam, which continue to interact with the electrons after the electron BGK modes have collapsed.
Linear analysis of stabilizing mechanisms for the kink instability
Authors: Wanex L. F. , Sotnikov V. I. , Bauer B. S. , Leboeuf J. N.
Published: April 2004

A study of stabilizing mechanisms for the m=1 kink instability in Z-pinch plasmas is presented. In the study we use a general set of equations that allows the investigation of the combined effect of axial sheared flow and an axial magnetic field on the development of the azimuthal mode m=1 kink magnetohydrodynamic (MHD) instability. This set of equations is applied to model Z-pinch plasmas in a nonideal MHD regime. The linear stage of the kink instability is analyzed numerically by introducing a perturbation into the equilibrium state of the plasma. A comparison of instability growth rates for different stabilizing combinations of axial sheared flow and an axial magnetic field is given. Growth rates of the m=1 kink mode are reported for both Bennett and parabolic equilibrium profiles.
Effects of plasma composition on backscatter, hot electron production, and propagation in underdense plasmas
Authors: Stevenson R. M. , Suter L. J. , Oades K. , Kruer W. , Slark G. E. , Fournier K. B. , Meezan N. , Kauffman R. , Miller M. , Glenzer S. , Niemann C. , Grun J. , Davis J. , Back C. , Thomas B.
Published: April 2004

A series of underdense laser plasma interaction experiments performed on the Helen laser [M. J. Norman et al., Appl. Opt. 41, 3497 (2002)] at the Atomic Weapons Establishment (AWE), U.K., using 2ω light have uncovered a strong dependence of laser backscatter and hot electron production on plasma composition. Using low-Z materials, we find a behavior familiar from previous 3ω work, the interchange of stimulated Raman scattering for Brillouin scattering as we change from gases that have high ion wave damping (e.g., C5H12) to gases with low ion wave damping (e.g., CO2). However, as Z is increased, we find that Brillouin scattering drops while Raman scattering remains low. For gases with Z greater than 18, it is possible to have long scalelength, underdense plasmas with both low Brillouin and Raman backscatter losses. Complementary measurements of hot electron production show efficient production of hot electrons in C5H12 plasmas approaching 0.25ncr, but changing the plasma composition can greatly suppress the hot electron production, even near 0.25ncr. Additional experiments indicate that by adding small amounts of high Z dopant, significant changes to the backscatter and hot electron production in C5H12 targets may be produced.
Nonlinear mixing behavior of the three-dimensional Rayleigh–Taylor instability at a decelerating interface
Authors: Drake R. P. , Leibrandt D. R. , Harding E. C. , Kuranz C. C. , Blackburn M. A. , Robey H. F. , Remington B. A. , Edwards M. J. , Miles A. R. , Perry T. S. , Wallace R. J. , Louis H. , Knauer J. P. , Arnett D.
Published: April 2004

Results are reported from the first experiments to explore the evolution of the Rayleigh–Taylor (RT) instability from intentionally three-dimensional (3D) initial conditions at an embedded, decelerating interface in a high-Reynolds-number flow. The experiments used ∼5 kJ of laser energy to produce a blast wave in polyimide and/or brominated plastic having an initial pressure of ∼50 Mbars. This blast wave shocked and then decelerated the perturbed interface between the first material and lower-density C foam. This caused the formation of a decelerating interface with an Atwood number ∼2/3, producing a long-term positive growth rate for the RT instability. The initial perturbations were a 3D perturbation in an “egg-crate” pattern with feature spacings of 71 μm in two orthogonal directions and peak-to-valley amplitudes of 5 μm. The resulting RT spikes appear to overtake the shock waves, moving at a large fraction of the predeceleration, “free-fall” velocity. This result was unanticipated by prior simulations and models.
Resistive wall mode stabilization with internal feedback coils in DIII-D
Authors: Strait E. J. , Bialek J. M. , Bogatu I. N. , Chance M. S. , Chu M. S. , Edgell D. H. , Garofalo A. M. , Jackson G. L. , Jayakumar R. J. , Jensen T. H. , Katsuro-Hopkins O. , Kim J. S. , La Haye R. J. , Lao L. L. , Makowski M. A. , Navratil G. A. , Okabayashi M. , Reimerdes H. , Scoville J. T. , Turnbull A. D. , Team DIII-D
Published: April 2004

A set of twelve coils for stability control has recently been installed inside the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] vacuum vessel, offering faster time response and a wider range of applied mode spectra than the previous external coils. Stabilization of the n=1 ideal kink mode is crucial to many high beta, steady-state tokamak scenarios. A resistive wall converts the kink to a slowly growing resistive wall mode (RWM). With feedback-controlled error field correction, rotational stabilization of the RWM has been sustained for more than 2.5 s. Using the internal coils, the required correction field is smaller than with the external coils, consistent with a better match to the mode spectrum of the error field. Initial experiments in direct feedback control have stabilized the RWMs at higher beta and lower rotation than could be achieved by the external coils in similar plasmas, in qualitative agreement with numerical modeling. The new coils have also allowed wall stabilization in plasmas with toroidal beta up to 6%, almost 50% greater than the no wall limit.
Beta scaling of transport on the DIII-D Tokamak: Is transport electrostatic or electromagnetic?
Authors: Petty C. C. , Luce T. C. , McDonald D. C. , Mandrekas J. , Wade M. R. , Candy J. , Cordey J. G. , Drozdov V. , Evans T. E. , Ferron J. R. , Groebner R. J. , Hyatt A. W. , Jackson G. L. , La Haye R. J. , Osborne T. H. , Waltz R. E.
Published: April 2004

Determining the scaling of transport with beta (β), the ratio of the plasma kinetic pressure to the magnetic pressure, helps to differentiate between various proposed theories of turbulent transport since mechanisms that are primarily electrostatic show little change in transport with increasing β, while primarily electromagnetic mechanisms generally have a strong unfavorable β scaling. Experiments on the DIII-D tokamak [J.L. Luxon, Nucl. Fusion 42, 614 (2002)] have measured the β scaling of heat transport with all of the other dimensionless parameters held constant in high confinement mode (H-mode) plasmas with edge localized modes. A four point scan varied β from 30% to 85% of the ideal ballooning stability limit (normalized beta from 1.0 to 2.8) and found no change in the normalized confinement time, i.e., Bτth∝β−0.01±0.09. The measured thermal diffusivities, normalized to the Bohm diffusion coefficient, also did not vary during the β scan to within the experimental uncertainties, whereas the normalized helium particle transport decreased with increasing β. The H-mode pedestal β varied in concert with the core β and showed no signs of saturation. This weak, possibly nonexistent, β scaling of transport favors primarily electrostatic mechanisms such as E×B transport, and is in marked disagreement with the strong unfavorable β dependence contained in empirical scaling relations derived from multimachine H-mode confinement databases.
Recent progress on steady-state high-performance plasma research in the Hefei Tokamak-7
Authors: Wan Baonian , Shi Yuejiang , Xu Guosheng , Gong Xianzu , Qian Jinping , Zhao Yanping , Shan Jiafang , Zhao Junyu , Hu Liqun , Li Jiangang , Kuang Guangli , Lv Bo , Ling Bili , Wu Zhenwei , Liu Fukun , Mao Yuzhou , Gao Xiang , Jie Yanxin , Mao Jianshan , Zhou Qing , Huang Jun , Xie Jikang ,   HT-7 Team, Gentle K. W. , Rowan W. L. , Philippe P. E. , Huang H. , Lao L. L. , Chan V. S. , Watari T. , Seki T.
Published: April 2004

High performance discharges under steady-state condition in the Hefei Tokamak-7 (HT-7) have been investigated. Lower hybrid current drive (LHCD) was used both for sustaining plasma current and current density profile control. The experiments demonstrated that features of ion Bernstein wave heating in controlling the electron pressure profile can be integrated into LHCD plasmas and the assist localization of LHCD. This local synergy effect was used to tailor the current density profile in a negative shear configuration and to control the internal transport barrier (ITB) under steady-state conditions. The high performance with a stationary ITB at the footprint of the minimum q and βNH89>2 was sustained for >220 τE or >20 τCR. The fraction of noninductive plasma current was larger than 80% in such discharges with considerable bootstrap current. The duration at H89>1.2 and βN∼1 has been extended to nearly 8 s, longer than 400 τE. More than 90% of the plasma current was sustained by LHCD and bootstrap current. High-plasma performance and sustaining time was limited by the magnetohydrodynamic instabilities and the recycling, which caused an uncontrollable rise of the electron density.
Mini-conference on laser-induced fluorescence in plasmas
Authors: Skiff Fred , Bollinger John
Published: April 2004

A mini-conference on laser-induced fluorescence in plasmas was held on 29 October 2003 as part of the 45th meeting of the Division of Plasma Physics of the American Physical Society. This paper summarizes material discussed in the talks presented as part of the mini-conference. The mini-conference was also an occasion to honor Raul Stern on his 75th birthday and to recognize his many contributions to plasma physics and to the applications of laser-induced fluorescence.
Simple theory of the optical absorption coefficient in nonparabolic semiconductors
Authors: Chakraborty P. K. , Singh L. J. , Ghatak K. P.
Published: April 2004

A simple theory is developed of the optical absorption coefficient (OAC) in nonparabolic semiconductors on the basis of the three-band model of Kane, by considering the wave-vector (k⃗) dependence of the optical matrix element. It has been found that the OAC is proportional to [(ℏω)2−Eg2]1/2 (ℏω and Eg are the energy of the incident radiation and the bandgap, respectively) instead of [(ℏω)−Eg]1/2, the conventional form. It has been demonstrated, by taking n-InAs, n-InSb, Hg1−xCdxTe, and In1−xGaxAs1−yP1−y lattice matched to InP as examples, that the OAC increases with increasing photon energy and the value of the same coefficient in the three band model of Kane is greater than that in parabolic energy bands in all the cases. The well-known result for wide gap materials having parabolic energy bands has also been obtained from our generalized formulation under certain limiting condition.
Direct observation of microparticle gyromotion in a magnetized direct current glow discharge dusty plasma
Authors: Amatucci William E. , Walker David N. , Gatling George , Scime Earl E.
Published: April 2004

Laboratory observations of oscillatory motion of charged microparticles have been made in an argon dc glow discharge plasma created within a strong dc magnetic field. Measurements of the oscillation frequency and amplitude are consistent with the gyromotion of magnetized dust grains under the ambient plasma conditions. The measurements provide an effective method for the noninvasive determination of the charge on the observed microparticles. The observations also seem to indicate that the neutral drag force on the dust grains may be smaller than anticipated from the classical estimation.
Numerical study of zonal flow dynamics and electron transport in electron temperature gradient driven turbulence
Authors: Li Jiquan , Kishimoto Y.
Published: April 2004

The electron temperature gradient (ETG) driven turbulence in tokamak core plasmas is numerically investigated based on a three-dimensional gyrofluid model with adiabatic ion response. Attentions are focused on the zonal flow dynamics in ETG fluctuations and the resultant electron heat transport. A high electron energy confinement mode is found in the weak magnetic shear region, which is relevant to the self-organization behavior of turbulence through the enhanced zonal flow dynamics rather than the weak shear stabilization of ETG fluctuations. It is demonstrated that the weak shear favors the enhancement of zonal flows in ETG turbulence. The enhanced zonal flows may be plausibly limited by the excitation of a secondary Kelvin–Helmholtz mode, which is observed from the spatial spectral analyses and time-frequency wavelet analyses of turbulent fluctuations. Electromagnetic ETG simulations show that while the Ohkawa’s scaling of anomalous electron transport with beta, χe∝1/βe, is reproduced in the moderate shear plasma, the finite beta effect may reverse the Ohkawa’s scaling in weak shear ETG turbulence due to the reduction of zonal flow generation by the magnetic Reynolds stress. Further, it is shown that the toroidal coupling enhances the zonal flow while it destabilizes the ETG mode. Hence, the electron transport seems insensitive to the toroidicity in the weak shear plasma due to the complex destabilizing and stabilizing competitions.
Self-consistent Langevin theory of self-excited oscillations of grains in plasma sheaths
Authors: Resendes D. P. , Sorasio G. , Shukla P. K.
Published: April 2004

Strong kinetic heating of grains is frequently associated with a melting transition in plasma crystals. At high pressures, above 100 mTorr, the melting transition is preceded by a vibrational phase whereas at low pressures, below 50 mTorr, observed large amplitude self-excited oscillations can lead to lattice disruption. At such low background gas pressures, only single layer crystals are formed. This work focuses on the low pressure regime and provides a theory of the self-excited oscillations which explains both the pressure and the power dependence of these oscillations as well as their threshold behavior. The implications for the melting transition are pointed out.
Ultra-high electron beam power and energy densities using a plasma-filled rod-pinch diode
Authors: Weber B. V. , Commisso R. J. , Cooperstein G. , Hinshelwood D. D. , Mosher D. , Ottinger P. F. , Ponce D. M. , Schumer J. W. , Stephanakis S. J. , Strasburg S. D. , Swanekamp S. B. , Young F. C.
Published: April 2004

The plasma-filled rod-pinch diode is a new technique to concentrate an intense electron beam to high power and energy density. Current from a pulsed power generator (typically ∼MV, MA, 100 ns pulse duration) flows through the injected plasma, which short-circuits the diode for 10–70 ns, then the impedance increases and a large fraction of the ∼MeV electron-beam energy is deposited at the tip of a 1 mm diameter, tapered rod anode, producing a small (sub-mm diameter), intense x-ray source. The current and voltage parameters imply 20–150 μm effective anode-cathode gaps at the time of maximum radiation, much smaller gaps than can be used between metal electrodes without premature shorting. Interferometric diagnostics indicate that the current initially sweeps up plasma in a snowplow-like manner, convecting current toward the rod tip. The density distribution is more diffuse at the time of beam formation with a low-density region near the rod surface where gap formation could occur. Particle simulations of the beam formation phase are dominated by rapid field penetration along the anode and radial J×B forces leading to gap formation and high-energy beam propagation to the rod tip. Beam deposition at the rod tip produces a high thermal energy-density (∼0.75 MJ/cm3), highly ionized (Z∼10, T∼25 eV) expanding tungsten plasma. Potential applications of this technique include improved radiography sources, high-energy-density plasma generation, and intense 10–100 keV x-ray production for nuclear-weapon-effects testing.
Ion-beam mixing in an immiscible Fe/Ag multilayer film
Authors: Amirthapandian S. , Panigrahi B. K. , Srivastava A. K. , Dhara S. , Gupta Ajay , Sastry V. S. , Nandedkar R. V. , Nair K. G. M. , Narayanasamy A.
Published: April 2004

Ion-beam mixing of the thermally immiscible Fe/Ag system is studied by 90 keV Ar+-ion irradiation of Fe/Ag multilayer at 325 K and the evolution of microstructure is studied by x-ray diffraction (XRD), x-ray reflectivity, and transmission electron microscopy (TEM). XRD measurements did not show any evidence of a additional phase formation or increase in solubility due to mixing of Fe in Ag. X-ray reflectivity analysis shows an initial sharpening at the interface for a fluence of 1×1016 ions/cm2 and the destruction of multilayer periodicity is observed for higher fluences. The microstructural studies by TEM show a reduction in Ag particle size with fluence. The size of Ag nanoclusters was optimum at a fluence of 7×1016 ions/cm2 and was found to be in the range of 10–20 nm. The particle density decreases at low fluence and on further irradiation, the particle density increases at higher ion fluences. This indicates the nucleation of Ag particles presumably due to long-range transport of Ag atoms. These Ag atom clusters give rise to a granular microstructure.
Modulated wavepackets associated with longitudinal dust grain oscillations in a dusty plasma crystal
Authors: Kourakis I. , Shukla P. K.
Published: April 2004

The nonlinear amplitude modulation of longitudinal dust lattice waves (LDLWs) propagating in a dusty plasma crystal is investigated in a continuum approximation. It is shown that long wavelength LDLWs are modulationally stable, while shorter wavelengths may be unstable. The possibility for the formation and propagation of different envelope localized excitations is discussed. It is shown that the total grain displacement bears a (weak) constant displacement (zeroth harmonic mode), due to the asymmetric form of the nonlinear interaction potential. The existence of asymmetric envelope localized modes is predicted. The types and characteristics of these coherent nonlinear structures are discussed.
The electromagnet probes
Authors: Shadman K.
Published: April 2004

This paper gives an overview of probes that are able to measure the anisotropy of the electron velocity distribution function in magnetized plasma; that is, probes that are able to retrieve information about the distribution of the perpendicular gyration speeds in addition to the speed distribution along the magnetic field line. In particular, the paper introduces a new addition to this family, the gridded electromagnet probe, and addresses its advantages over the configurations considered in the past. The new probe is found to be best suited for making measurements in plasmas that employ large magnetic fields, B∼1 kG, but have low densities, n<1011 cm−3.
Characteristics of sawtooth oscillations observed in the compact helical system
Authors: Takagi S. , Toi K. , Takechi M. , Murakami S. , Tanaka K. , Nishimura S. , Isobe M. , Matsuoka K. , Minami T. , Okamura S. , Osakabe M. , Takahashi C. , Yoshimura Y. ,   CHS Group
Published: April 2004

Sawtooth oscillations are often detected in the signals of several diagnostics during tangential neutral beam injection (NBI) heating in the compact helical system (CHS) [K. Matsuoka et al., Plasma Pysics and Controlled Nuclear Fusion Research, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 2, p. 441]. The sawtooth crashes are closely related to the q=2 (q is the safety factor) rational surface located on the normalized minor radius ρ∼0.5 and most of the crashes indicate a character of an annular crash. The disturbance of plasma parameters on the magnetic axis depends on the toroidal plasma beta and the size of the q=2 surface. The time scale of the crash is fairly large to be 0.5–1.0 ms which is an order of magnitude larger than that in tokamaks. Two types of m/n=2/1 (m and n are poloidal and toroidal mode numbers, respectively) magnetic fluctuations, which are fishbone-like burst mode (FB) and low frequency ideal/resistive interchange mode (LF mode), grow just before the crash. Those internal structure and time evolution across the crash clearly indicate that the sawtooth crash in NBI heated plasmas of CHS is induced by ideal/resistive interchange mode not by energetic ion driven mode.
Mini-conference and related sessions on laboratory plasma astrophysics
Authors: Ji Hantao , Brown Michael , Hsu Scott C. , Li Hui , Drake R. Paul
Published: April 2004

This paper provides a summary of some major physics issues and future perspectives discussed in the Mini-Conference on Laboratory Plasma Astrophysics. This mini-conference, sponsored by the Topical Group on Plasma Astrophysics, was held as part of the American Physical Society’s Division of Plasma Physics 2003 Annual Meeting (October 27–31, 2003). Also included are brief summaries of selected talks on the same topic presented at two invited paper sessions (including a tutorial) and two contributed focus oral sessions, which were organized in coordination with the mini-conference by the same organizers.
Dust voids due to dust-phase-space vortices in plasmas
Authors: Mamun A. A. , Shukla P. K.
Published: April 2004

It is shown that a dust void in a dusty plasma can be formed due to the presence of positive plasma potential, which is built up owing to a nonisothermal dust particle distribution arising from negatively charged dust particle trapping. It is found that the dust void shrinks with the increase of the dust charge density, while it enlarges with the increase of the dust temperature. The implications of our results to the possibility for the formation of dust voids in space dusty plasmas, particularly in Saturn’s dusty rings, is discussed.
Probe induced voids in a dusty plasma
Authors: Thomas E. , Avinash K. , Merlino R. L.
Published: April 2004

An experimental study of the formation of voids (dust-free regions) around negatively biased probes in a dusty plasma is described. Stable voids are maintained by the balance of electric and ion drag forces on the dust particles. A theoretical model is proposed to explain how the size of the void scales with the probe bias potential.
Reduction of asymmetry transport in the annular Penning trap
Authors: Robertson Scott , Sternovsky Zoltan , Walch Bob
Published: April 2004

In the Penning trap, there is transport of electrons in the limit of zero gas pressure that arises from asymmetric stray electric fields. In an annular version of the Penning trap, this asymmetry transport is shown to be greatly reduced when the plasma-facing surfaces are coated with colloidal graphite. In a separate device, an emissive probe is used to examine the space potential a few millimeters above coated and uncoated surfaces. It is found that the rms potential variation is approximately 250 mV for uncoated surfaces and 15 mV for coated surfaces. The characteristic length scale of the inhomogeneities is ∼1 cm. Glow-discharge cleaning, which is easily renewed, is shown to reduce the potential variation to the same level that is obtained with the colloidal graphite coating.
Integrated implosion/heating studies for advanced fast ignition
Authors: Norreys P. A. , Lancaster K. L. , Murphy C. D. , Habara H. , Karsch S. , Clarke R. J. , Collier J. , Heathcote R. , Hemandez-Gomez C. , Hawkes S. , Neely D. , Hutchinson M. H. R. , Evans R. G. , Borghesi M. , Romagnani L. , Zepf M. , Akli K. , King J. A. , Zhang B. , Freeman R. R. , MacKinnon A. J. , Hatchett S. P. , Patel P. , Snavely R. , Key M. H. , Nikroo A. , Stephens R. , Stoeckl C. , Tanaka K. A. , Norimatsu T. , Toyama Y. , Kodama R.
Published: April 2004

Integrated experiments to investigate the ultrafast heating of implosions using cone/shell geometries have been performed at the Rutherford Appleton Laboratory. The experiments used the 1054 nm, nanosecond, 0.9 kJ output of the VULCAN Nd:glass laser to drive 486 μm diameter, 6 μm wall thickness Cu-doped deuterated plastic (CD) shells in 6-beam cubic symmetry. Measurements of the opacity of the compressed plasma using two-dimensional spatially resolved Ti-Kα x-ray radiography suggest that densities of 4 g cm−3 and areal densities of 40 mg cm−2 were achieved at stagnation. Upper limits on the heating with both 1 ps and 10 ps pulses were deduced from the fluorescent yield from the Cu dopant. The data suggest that control of the preformed plasma scale-length inside the cone is necessary for efficient coupling to the compressed plasma.
Propagation of nonplanar dust-acoustic envelope solitary waves in a two-ion-temperature dusty plasma
Authors: Xue Ju-Kui
Published: April 2004

The evolution of the cylindrical and spherical dust-acoustic envelope solitary wave (DAESW) in an unmagnetized dusty plasma consisting of negatively charged dust fluid and ions of two different temperatures is investigated. By using the reductive perturbation method, the cylindrical and spherical geometry-modified nonlinear Schrödinger equation (GMNLSE) is obtained. The change of the DAESW amplitude due to the cylindrical and spherical geometry effects is deduced analytically. It is shown that there exist two time ranges. On the other hand, the wave amplitude changes with time τ as (τ0/τ)m/2 when the geometry effect is stronger and as (τ0/τ)m when the geometry effect is weaker, where τ0 is the initial time, and m=1 (2) refers to the cylindrical (spherical) case. The theoretical results are verified by the numerical calculation for the GMNLSE. The modulational instability of dust-acoustic waves governed by the GMNLSE is also presented. It is shown that the propagation of the DAESW in cylindrical geometry, spherical geometry, and planar one-dimensional geometry are very different. The presence of a second component of ions would modify the nature of the modulation instabilities.
A high density field reversed configuration (FRC) target for magnetized target fusion: First internal profile measurements of a high density FRC
Authors: Intrator T. , Zhang S. Y. , Degnan J. H. , Furno I. , Grabowski C. , Hsu S. C. , Ruden E. L. , Sanchez P. G. , Taccetti J. M. , Tuszewski M. , Waganaar W. J. , Wurden G. A.
Published: April 2004

Magnetized target fusion (MTF) is a potentially low cost path to fusion, intermediate in plasma regime between magnetic and inertial fusion energy. It requires compression of a magnetized target plasma and consequent heating to fusion relevant conditions inside a converging flux conserver. To demonstrate the physics basis for MTF, a field reversed configuration (FRC) target plasma has been chosen that will ultimately be compressed within an imploding metal liner. The required FRC will need large density, and this regime is being explored by the FRX–L (FRC-Liner) experiment. All theta pinch formed FRCs have some shock heating during formation, but FRX–L depends further on large ohmic heating from magnetic flux annihilation to heat the high density (2–5×1022 m−3), plasma to a temperature of Te+Ti≈500 eV. At the field null, anomalous resistivity is typically invoked to characterize the resistive like flux dissipation process. The first resistivity estimate for a high density collisional FRC is shown here. The flux dissipation process is both a key issue for MTF and an important underlying physics question.
Smoothness of turbulent transport across a minimum-q surface
Authors: Candy J. , Waltz R. E. , Rosenbluth M. N.
Published: April 2004

Some controversy exists over the role of weak or reversed shear in the formation of internal transport barriers. One theory attributes the formation of internal transport barriers to a gap in global wave structures in the minimum-q region. It is shown that in general no such gap exists, and that energy transport is smooth and increasing across such a minimum-q region.
Optical transitions, absorption intensities, and intermanifold emission cross sections of Pr3+(4f2) in Ca5(PO4)3F crystal host
Authors: Sardar Dhiraj K. , Russell Charles C.
Published: April 2004

A spectroscopic Judd–Ofelt investigation has been performed on Pr3+ ions doped in calcium fluorapatite, Ca5(PO4)3F, belonging to the apatite structure family. The standard Judd–Ofelt analysis was applied to the room temperature absorption intensities of Pr3+ transitions to determine the phenomenological intensity parameters: Ω2, Ω4, and Ω6. Values of the intensity parameters were subsequently used to determine the decay rates (emission probabilities), radiative lifetimes, and branching ratios of the principal intermanifold transitions of Pr3+ from the P23, D21, and P03 manifold states to the lower-lying manifolds. In addition, the room temperature fluorescence lifetimes and emission cross sections of the P23→H53, D21→H43, and P03→F23 transitions were measured; these values were compared with those of Nd3+:yttritium–aluminum–garnet and Pr3+:Sr5(PO4)3 (known as S–FAP).
Characterizing well-ordered CuO nanofibrils synthesized through gas-solid reactions
Authors: Lin Hung-Hsiao , Wang Chih-Yuan , Shih Han C. , Chen Jin-Ming , Hsieh Chien-Te
Published: April 2004

Films of well-ordered crystalline copper oxide (CuO) nanofibril arrays were synthesized using a procedure involving electrodeposition followed by a gas-solid reaction. Analyses showed that the nanocrystalline CuO nanofibrils with a mean length of 8 μm have an average density of 107–108/cm2. Photoluminescence measurements showed a main peak in the visible light band at 410 nm, and the band gap energy was estimated to be 1.67 eV. It was found that the film of aligned CuO nanofibrils has typical Fowler–Nordheim plots in the follow-up electron field emission test. Typical turn-on voltage was detected at ∼6 V/μm with an emission area of 1 mm2. The Fowler–Nordheim model was employed to analyze the I–V data obtained. The work function of the nanofibrils was estimated to be in the range of 4.1–4.3 eV.