The energy dependence of the total charm cross section (open access)

The energy dependence of the total charm cross section

We discuss the energy dependence of the total charm cross section and some of its theoretical uncertainties including the quark mass, scale choice and the parton densities. We compare the next-to-leading order calculation of the total cross section with results obtained using PYTHIA.
Date: October 18, 2007
Creator: Vogt, R
Object Type: Article
System: The UNT Digital Library
Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials (open access)

Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials

Laser-induced breakdown in the bulk of transparent dielectric materials is associated with the generation of extreme localized conditions of temperatures and pressures. In this work, we perform pump and probe damage testing experiments to investigate the evolution of transient absorption by the host material arising from modifications following confined laser energy deposition in fused silica and DKDP materials. Specifically, we measure the size of the damage sites observed in the region of spatial overlap between the pump and probe pulses versus probe time delay and energy. Results of this proof-of-principle experimental work confirm that material modifications under extreme conditions created during a damage event include transient optical absorption. In addition, we found that the relaxation times of the induced absorption are very distinct for DKDP and SiO{sub 2} even under identical excitation conditions, on the order of 100 ns and 100 {micro}s, respectively.
Date: October 18, 2007
Creator: Negres, R A; Feit, M D; DeMange, P; Bude, J D & Demos, S G
Object Type: Article
System: The UNT Digital Library
A High-Order Finite-Volume Algorithm for Fokker-Planck Collisions in Magnetized Plasmas (open access)

A High-Order Finite-Volume Algorithm for Fokker-Planck Collisions in Magnetized Plasmas

A high-order finite volume algorithm is developed for the Fokker-Planck Operator (FPO) describing Coulomb collisions in strongly magnetized plasmas. The algorithm is based on a general fourth-order reconstruction scheme for an unstructured grid in the velocity space spanned by parallel velocity and magnetic moment. The method provides density conservation and high-order-accurate evaluation of the FPO independent of the choice of the velocity coordinates. As an example, a linearized FPO in constant-of-motion coordinates, i.e. the total energy and the magnetic moment, is developed using the present algorithm combined with a cut-cell merging procedure. Numerical tests include the Spitzer thermalization problem and the return to isotropy for distributions initialized with velocity space loss cones. Utilization of the method for a nonlinear FPO is straightforward but requires evaluation of the Rosenbluth potentials.
Date: April 18, 2007
Creator: Xiong, Z; Cohen, R H; Rognlien, T D & Xu, X Q
Object Type: Article
System: The UNT Digital Library
Groundwater Flow and Thermal Modeling to Support a Preferred Conceptual Model for the Large Hydraulic Gradient North of Yucca Mountain (open access)

Groundwater Flow and Thermal Modeling to Support a Preferred Conceptual Model for the Large Hydraulic Gradient North of Yucca Mountain

The purpose of this study is to report on the results of a preliminary modeling framework to investigate the causes of the large hydraulic gradient north of Yucca Mountain. This study builds on the Saturated Zone Site-Scale Flow and Transport Model (referenced herein as the Site-scale model (Zyvoloski, 2004a), which is a three-dimensional saturated zone model of the Yucca Mountain area. Groundwater flow was simulated under natural conditions. The model framework and grid design describe the geologic layering and the calibration parameters describe the hydrogeology. The Site-scale model is calibrated to hydraulic heads, fluid temperature, and groundwater flowpaths. One area of interest in the Site-scale model represents the large hydraulic gradient north of Yucca Mountain. Nearby water levels suggest over 200 meters of hydraulic head difference in less than 1,000 meters horizontal distance. Given the geologic conceptual models defined by various hydrogeologic reports (Faunt, 2000, 2001; Zyvoloski, 2004b), no definitive explanation has been found for the cause of the large hydraulic gradient. Luckey et al. (1996) presents several possible explanations for the large hydraulic gradient as provided below: The gradient is simply the result of flow through the upper volcanic confining unit, which is nearly 300 meters thick near the …
Date: December 18, 2007
Creator: McGraw, D. & Oberlander, P.
Object Type: Report
System: The UNT Digital Library
Isothermal Martensitic and Pressure-Induced (delta) to (alpha)' Phase Transformations in a Pu-Ga Alloy (open access)

Isothermal Martensitic and Pressure-Induced (delta) to (alpha)' Phase Transformations in a Pu-Ga Alloy

None
Date: December 18, 2007
Creator: Schwartz, A J; Wall, M A; Farber, D L; Moore, K T & Blobaum, K M
Object Type: Article
System: The UNT Digital Library
Modeling Incoherent Electron Cloud Effects (open access)

Modeling Incoherent Electron Cloud Effects

Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed.
Date: June 18, 2007
Creator: Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D. et al.
Object Type: Article
System: The UNT Digital Library
Temperature dependence of protein hydration hydrodynamics by molecular dynamics simulations. (open access)

Temperature dependence of protein hydration hydrodynamics by molecular dynamics simulations.

The dynamics of water molecules near the protein surface are different from those of bulk water and influence the structure and dynamics of the protein itself. To elucidate the temperature dependence hydration dynamics of water molecules, we present results from the molecular dynamic simulation of the water molecules surrounding two proteins (Carboxypeptidase inhibitor and Ovomucoid) at seven different temperatures (T=273 to 303 K, in increments of 5 K). Translational diffusion coefficients of the surface water and bulk water molecules were estimated from 2 ns molecular dynamics simulation trajectories. Temperature dependence of the estimated bulk water diffusion closely reflects the experimental values, while hydration water diffusion is retarded significantly due to the protein. Protein surface induced scaling of translational dynamics of the hydration waters is uniform over the temperature range studied, suggesting the importance protein-water interactions.
Date: July 18, 2007
Creator: Lau, E Y & Krishnan, V V
Object Type: Article
System: The UNT Digital Library
Dielectric Wall Accelerator Technology (open access)

Dielectric Wall Accelerator Technology

The dielectric wall accelerator (DWA) is a compact pulsed power device where the pulse forming lines, switching, and vacuum wall are integrated into a single compact geometry. For this effort, we initiated a extensive compact pulsed power development program and have pursued the study of switching (gas, oil, laser induced surface flashover and photoconductive), dielectrics (ceramics and nanoparticle composites), pulse forming line topologies (asymmetric and symmetric Blumleins and zero integral pulse forming lines), and multilayered vacuum insulator (HGI) technology. Finally, we fabricated an accelerator cell for test on ETAII (a 5.5 MeV, 2 kA, 70 ns pulsewidth electron beam accelerator). We review our past results and report on the progress of accelerator cell testing.
Date: October 18, 2007
Creator: Sampayan, S.; Caporaso, G.; Chen, Y.; Harris, J.; Hawkins, S.; Holmes, C. et al.
Object Type: Article
System: The UNT Digital Library
Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey (open access)

Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey

We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by coadding large ensembles of radio image cut-outs from the FIRST survey, as almost all of the sources are individually undetected. We correlate the median radio flux densities against a range of other sample properties, including median values for redshift, [O III] luminosity, emission line ratios, and the strength of the 4000{angstrom} break. We detect a strong trend for sources that are actively undergoing star-formation to have excess radio emission beyond the {approx} 10{sup 28} ergs s{sup -1} Hz{sup -1} level found for sources without any discernible star-formation. Furthermore, this additional radio emission correlates well with the strength of the 4000{angstrom} break in the optical spectrum, and may be used to assess the age of the star-forming component. We examine two subsamples, one containing the systems with emission line ratios most like star-forming systems, and one with the sources that have characteristic AGN ratios. This division also separates the mechanism responsible for the radio emission (star-formation vs. AGN). For both cases we find a strong, almost identical, correlation between [O III] and radio luminosity, …
Date: April 18, 2007
Creator: de Vries, W. H.; Hodge, J. A.; Becker, R. H.; White, R. L. & Helfand, D. J.
Object Type: Article
System: The UNT Digital Library
Enhancing Price Response Programs through Auto-DR: California's 2007 Implementation Experience (open access)

Enhancing Price Response Programs through Auto-DR: California's 2007 Implementation Experience

This paper describes automated demand response (Auto-DR) activities, an innovative effort in California to ensure that DR programs produce effective and sustainable impacts. Through the application of automation and communication technologies coupled with well-designed incentives and DR programs such as Critical Peak Pricing (CPP) and Demand Bidding (DBP), Auto-DR is opening up the opportunity for many different types of buildings to effectively participate in DR programs. We present the results of Auto-DR implementation efforts by the three California investor-owned utilities for the Summer of 2007. The presentation emphasizes Pacific Gas and Electric Company's (PG&E) Auto-DR efforts, which represents the largest in the state. PG&E's goal was to recruit, install, test and operate 15 megawatts of Auto-DR system capability. We describe the unique delivery approaches, including optimizing the utility incentive structures designed to foster an Auto-DR service provider community. We also show how PG&E's Critical Peak Pricing (CPP) and Demand Bidding (DBP) options were called and executed under the automation platform. Finally, we show the results of the Auto-DR systems installed and operational during 2007, which surpassed PG&E's Auto-DR goals. Auto-DR is being implemented by a multi-disciplinary team including the California Investor Owned Utilities (IOUs), energy consultants, energy management control system …
Date: December 18, 2007
Creator: Kiliccote, Sila; Wikler, Greg; Chiu, Albert; Piette, Mary Ann; Kiliccote, Sila; Hennage, Dan et al.
Object Type: Article
System: The UNT Digital Library

E85 and Biodiesel Deployment

Presentation outlines industry trends and statistics revolving around the use and production of ethanol and biodiesel.
Date: September 18, 2007
Creator: Harrow, G.
Object Type: Presentation
System: The UNT Digital Library
Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br (open access)

Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br

Trivalent bismuth luminescence is reported in three Sillenbismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. Thesecompounds exhibit Bi 6s6->6 s2 emission under UV and X-ray radiation.At room temperature, BaBiO2Cl shows the most intense light emission, withspectral and decay properties similar to those found in Bi4Ge3O12 (BGO).At low temperatures, each phase show an increase in the photoluminescenceintensities and a narrowing of the emission peaks. In contrast to thetemperature dependence of BGO, X-ray excited luminescence intensities ofall three phases remain relatively constant throughout the temperaturerange 10 - 295 K. This result indicates that the Sillen phases undergoless thermal quenching than BGO. The low temperature and room temperatureradio-luminescence decay times were determined from pulsed x-raymeasurements. At room temperature, SrBiO2Cl exhibits faster decays thanBGO, while, BaBiO2Cl and BaBiO2Br have decay times similar toBGO.
Date: January 18, 2007
Creator: Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith E. & Derenzo,Stephen E.
Object Type: Article
System: The UNT Digital Library
Promoting Energy Efficiency in Cement Making: The ENERGY STAR(R)for Industry Program (open access)

Promoting Energy Efficiency in Cement Making: The ENERGY STAR(R)for Industry Program

None
Date: August 18, 2007
Creator: Masanet, Eric & Worrell, Ernst
Object Type: Report
System: The UNT Digital Library
Criticality-Control Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings (open access)

Criticality-Control Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings

Amorphous metal and ceramic thermal spray coatings have been developed that can be used to enhance the corrosion resistance of containers for the transportation, aging and disposal of spent nuclear fuel and high-level radioactive wastes. Iron-based amorphous metal formulations with chromium, molybdenum and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials, and their stability at high neutron doses, enable them to serve as high efficiency neutron absorbers for criticality control. The high boron content of Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5) makes it an effective neutron absorber, and suitable for criticality control applications. Average measured values of the neutron absorption cross section in transmission ({Sigma}{sub t}) for Type 316L stainless steel, Alloy C-22, borated stainless steel, a Ni-Cr-Mo-Gd alloy, and SAM2X5 have been determined to be approximately 1.1, 1.3, 2.3, 3.8 and 7.1 cm{sup -1}, respectively.
Date: July 18, 2007
Creator: Farmer, J & Choi, J
Object Type: Report
System: The UNT Digital Library
Office of the Chief Financial Officer Annual Report 2007 (open access)

Office of the Chief Financial Officer Annual Report 2007

2007 was a year of progress and challenges for the Office of the Chief Financial Officer (OCFO). I believe that with the addition of a new Controller, the OCFO senior management team is stronger than ever. With the new Controller on board, the senior management team spent two intensive days updating our strategic plan for the next five years ending in 2012, while making sure that we continue to execute on our existing strategic initiatives. In 2007 the Budget Office, teaming with Human Resources, worked diligently with our colleagues on campus to reengineer the Multi-Location Appointment (MLA) process, making it easier for our Principal Investigators (PIs) to work simultaneously between the Laboratory and UC campuses. The hiring of a point-of-contact in Human Resources to administer the program will also make the process flow smoother. In order to increase our financial flexibility, the OCFO worked with the Department of Energy (DOE) to win approval to reduce the burden rates on research and development (R&D) subcontracts and Intra-University Transfers (IUT). The Budget Office also performed a 'return on investment' (ROI) analysis to secure UCRP funding for a much needed vocational rehabilitation counselor. This new counselor now works with employees who are on …
Date: December 18, 2007
Creator: Fernandez, Jeffrey
Object Type: Report
System: The UNT Digital Library
CRD Report (open access)

CRD Report

This report has the following articles: (1) Deconstructing Microbes--metagenomic research on bugs in termites relies on new data analysis tools; (2) Popular Science--a nanomaterial research paper in Nano Letters drew strong interest from the scientific community; (3) Direct Approach--researchers employ an algorithm to solve an energy-reduction issue essential in describing complex physical system; and (4) SciDAC Special--A science journal features research on petascale enabling technologies.
Date: December 18, 2007
Creator: Wang, Ucilia
Object Type: Report
System: The UNT Digital Library
Diagnostic evaluation of a multiplexed RT-PCR microsphere array assay for the detection of foot-and-mouth and look-alike disease viruses (open access)

Diagnostic evaluation of a multiplexed RT-PCR microsphere array assay for the detection of foot-and-mouth and look-alike disease viruses

A high-throughput multiplexed assay (Multiplex Version 1.0) was developed for the differential laboratory diagnosis of foot-and-mouth disease virus (FMDV) from viruses which cause clinically similar diseases of livestock. This assay simultaneously screens for five RNA and two DNA viruses using multiplexed reverse transcription PCR (mRT-PCR) amplification coupled with a microsphere hybridization array and flow-cytometric detection. Two of the seventeen primer-probe sets included in this multiplex assay were adopted from previously characterized real-time RT-PCR (rRT-PCR) assays for FMDV. The diagnostic accuracy of the mRT-PCR was evaluated using 287 field samples, including 248 (true positive n= 213, true negative n=34) from suspect cases of foot-and-mouth disease collected from 65 countries between 1965 and 2006 and 39 true negative samples collected from healthy animals. The mRT-PCR assay results were compared with two singleplex rRT-PCR assays, using virus isolation with antigen-ELISA as the reference method. The diagnostic sensitivity of the mRT-PCR assay for FMDV was 93.9% [95% C.I. 89.8-96.4%], compared to 98.1% [95% C.I. 95.3-99.3%] for the two singleplex rRTPCR assays used in combination. In addition, the assay could reliably differentiate between FMDV and other vesicular viruses such as swine vesicular disease virus and vesicular exanthema of swine virus. Interestingly, the mRT-PCR detected parapoxvirus …
Date: September 18, 2007
Creator: Hindson, B J; Baker, B R; Bentley Tammero, L F; Lenhoff, R J; Naraghi-Arani, P; Vitalis, E A et al.
Object Type: Report
System: The UNT Digital Library
Simulation of Comet Impact and Survivability of Organic Compounds (open access)

Simulation of Comet Impact and Survivability of Organic Compounds

Comets have long been proposed as a potential means for the transport of complex organic compounds to early Earth. For this to be a viable mechanism, a significant fraction of organic compounds must survive the high temperatures due to impact. We have undertaken three-dimensional numerical simulations to track the thermodynamic state of a comet during oblique impacts. The comet was modeled as a 1-km water-ice sphere impacting a basalt plane at 11.2 km/s; impact angles of 15{sup o} (from horizontal), 30{sup o}, 45{sup o}, 65{sup o}, and 90{sup o} (normal impact) were examined. The survival of organic cometary material, modeled as water ice for simplicity, was calculated using three criteria: (1) peak temperatures, (2) the thermodynamic phase of H{sub 2}O, and (3) final temperature upon isentropic unloading. For impact angles greater than or equal to 30{sup o}, no organic material is expected to survive the impact. For the 15{sup o} impact, most of the material survives the initial impact and significant fractions (55%, 25%, and 44%, respectively) satisfy each survival criterion at 1 second. Heating due to deceleration, in addition to shock heating, plays a role in the heating of the cometary material for nonnormal impacts. This effect is more …
Date: July 18, 2007
Creator: Liu, B T; Lomov, I N; Blank, J G & Antoun, T H
Object Type: Article
System: The UNT Digital Library
Magnetohydrodynamic Simulations of Disk GalaxyFormation: the Magnetization of The Cold and Warm Medium (open access)

Magnetohydrodynamic Simulations of Disk GalaxyFormation: the Magnetization of The Cold and Warm Medium

Using magnetohydrodynamic (MHD) adaptive mesh refinement simulations, we study the formation and early evolution of disk galaxies with a magnetized interstellar medium. For a 10{sup 10} M{sub {circle_dot}} halo with initial NFW dark matter and gas profiles, we impose a uniform 10{sup -9} G magnetic field and follow its collapse, disk formation and evolution up to 1 Gyr. Comparing to a purely hydrodynamic simulation with the same initial condition, we find that a protogalactic field of this strength does not significantly influence the global disk properties. At the same time, the initial magnetic fields are quickly amplified by the differentially rotating turbulent disk. After the initial rapid amplification lasting {approx} 500 Myr, subsequent field amplification appears self-regulated. As a result, highly magnetized material begin to form above and below the disk. Interestingly, the field strengths in the self-regulated regime agrees well with the observed fields in the Milky Way galaxy both in the warm and the cold HI phase and do not change appreciably with time. Most of the cold phase shows a dispersion of order ten in the magnetic field strength. The global azimuthal magnetic fields reverse at different radii and the amplitude declines as a function of radius …
Date: December 18, 2007
Creator: Wang, Peng; Abel, Tom & /KIPAC, Menlo Park /Santa Barbara, KITP
Object Type: Article
System: The UNT Digital Library
STATUS OF THE INTERNATIONAL MUON IONIZATION COOLING EXPERIMENT(MICE) (open access)

STATUS OF THE INTERNATIONAL MUON IONIZATION COOLING EXPERIMENT(MICE)

An international experiment to demonstrate muon ionization cooling is scheduled for beam at Rutherford Appleton Laboratory (RAL) in 2007. The experiment comprises one cell of the Study II cooling channel [1], along with upstream and downstream detectors to identify individual muons and measure their initial and final 6D phase-space parameters to a precision of 0.1%. Magnetic design of the beam line and cooling channel are complete and portions are under construction. The experiment will be described, including cooling channel hardware designs, fabrication status, and running plans. Phase 1 of the experiment will prepare the beam line and provide detector systems, including time-of-flight, Cherenkov, scintillating-fiber trackers and their spectrometer solenoids, and an electromagnetic calorimeter. The Phase 2 system will add the cooling channel components, including liquid-hydrogen absorbers embedded in superconducting Focus Coil solenoids, 201-MHz normal-conducting RF cavities, and their surrounding Coupling Coil solenoids. The MICE Collaboration goal is to complete the experiment by 2010; progress toward this is discussed.
Date: July 18, 2007
Creator: Zisman, Michael S.
Object Type: Article
System: The UNT Digital Library
State-Resolved Dynamics of the CN(B2Sigma+) and CH(A2Delta)Excited Products Resulting from the VUV Photodissociation of CH3CN (open access)

State-Resolved Dynamics of the CN(B2Sigma+) and CH(A2Delta)Excited Products Resulting from the VUV Photodissociation of CH3CN

Fourier transform visible spectroscopy, in conjunction withVUV photons produced by a synchrotron, is employed to investigate thephotodissociation of CH3CN. Emission is observed from both theCN(B2Sigma+ - X2Sigma+) and CH(A2Delta - X2PI) transitions; only theformer is observed in spectra recorded at 10.2 and 11.5 eV, whereas bothare detected in the 16 eV spectrum. The rotational and vibrationaltemperatures of both the CN(B2Sigma+) and CH(A2Delta) radical productsare derived using a combination of spectral simulations and Boltzmannplots. The CN(B2Sigma+) fragment displays a bimodal rotationaldistribution in all cases. Trot(CN(B2Sigma+)) ranges from 375 to 600 K atlower K' and from 1840 to 7700 K at higher K' depending on the photonenergy used. Surprisal analyses indicate clear bimodal rotationaldistributions, suggesting CN(B2Sigma+) is formed via either linear orbent transition states, respectively, depending on the extent ofrotational excitation in this fragment. CH(A2Delta) has a singlerotational distribution when produced at 16 eV which results inTrot(CH(A2Delta)) = 4895 +- 140 K in nu' = 0 and 2590 +- 110 K in nu' =1. From thermodynamic calculations, it is evident that CH(A2Delta) isproduced along with CN(X2Sigma+) + H2. These products can be formed by atwo step mechanism (via excited CH3* and ground state CN(X2Sigma+) or aprocess similar to the "roaming" atom mechanism; …
Date: January 18, 2007
Creator: Howle, Chris R.; Arrowsmith, Alan N.; Chikan, Viktor & Leone,Stephen R.
Object Type: Article
System: The UNT Digital Library
Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps (open access)

Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps

Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps at a pair of identical sextupoles separated by -I section generate the net dispersion, while symmetric horizontal bumps induce a tune shift and beta beat. By combining two of these symmetric bumps with opposite signs, where the second pair is 90{sup o} away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER), there are four -I sextupole pairs per arc, located one after another 90{sup o} apart, where pairs 1 and 3 are at the same phase and pairs 2 and 4 are 90{sup o} away. By making two symmetric bumps with opposite sign in pairs 1 and 3, the tune shift and beta beat outside this region cancel, but there is a local change of phase and beta in the 2nd sextupole pair located in the middle. By using this bump knob, the LER lifetime improved by a factor of 3, losses by a factor of 5, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Optics analysis showed that the local phase change at the 2nd sextupole pair can compensate …
Date: December 18, 2007
Creator: Decker, F. J.; Nosochkov, Y.; Sullivan, M. & Yocky, G.
Object Type: Article
System: The UNT Digital Library
Geometric Gyrokinetic Theory for Edge Plasma (open access)

Geometric Gyrokinetic Theory for Edge Plasma

It turns out that gyrokinetic theory can be geometrically formulated as special cases of a geometrically generalized Vlasov-Maxwell system. It is proposed that the phase space of the spacetime is a 7-dimensional fiber bundle P over the 4-dimensional spacetime M, and that a Poincare-Cartan-Einstein 1-form {gamma} on the 7-dimensional phase space determines particles worldlines in the phase space. Through Liouville 6-form {Omega} and fiber integral, the 1-form {gamma} also uniquely defines a geometrically generalized Vlasov-Maxwell system as a field theory for the collective electromagnetic field. The geometric gyrokinetic theory is then developed as a special case of the geometrically generalized Vlasov-Maxwell system. In its most general form, gyrokinetic theory is about a symmetry, called gyro-symmetry, for magnetized plasmas, and the 1-form {gamma} again uniquely defines the gyro-symmetry. The objective is to decouple the gyro-phase dynamics from the rest of particle dynamics by finding the gyro-symmetry in {gamma}. Compared with other methods of deriving the gyrokinetic equations, the advantage of the geometric approach is that it allows any approximation based on mathematical simplification or physical intuition to be made at the 1-form level, and yet the field theories still have the desirable exact conservation properties such as phase space volume conservation …
Date: January 18, 2007
Creator: Qin, H; Cohen, R H; Nevins, W M & Xu, X Q
Object Type: Article
System: The UNT Digital Library
Electron-Cloud Build-Up: Summary (open access)

Electron-Cloud Build-Up: Summary

I present a summary of topics relevant to the electron-cloud build-up and dissipation that were presented at the International Workshop on Electron-Cloud Effects 'ECLOUD 07' (Daegu, S. Korea, April 9-12, 2007). This summary is not meant to be a comprehensive review of the talks. Rather, I focus on those developments that I found, in my personal opinion, especially interesting. The contributions, all excellent, are posted in http://chep.knu.ac.kr/ecloud07/.
Date: June 18, 2007
Creator: Furman, M. A.
Object Type: Article
System: The UNT Digital Library