Dissertations / Theses on the topic 'Radial Electric Field'
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Temple, Darren. "Experimental investigations into the radial electric field of MAST." Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540683.
Full textViezzer, Eleonora. "Radial electric field studies in the plasma edge of ASDEX." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-161574.
Full textHonda, Mitsuru. "Transport simulation of tokamak plasmas including plasma rotation and radial electric field." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136227.
Full textWilks, Theresa M. "Calculation of the radial electric field in the DIII-D tokamak edge plasma." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54988.
Full textErnst, Darin R. (Darin Richard) 1965. "Momentum transport, radial electric field, and ion thermal energy confinement in very high temperature plasmas." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50337.
Full textViezzer, Eleonora [Verfasser], and Hartmut [Akademischer Betreuer] Zohm. "Radial electric field studies in the plasma edge of ASDEX upgrade / Eleonora Viezzer. Betreuer: Hartmut Zohm." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1042899843/34.
Full textMcDermott, Rachael Marie. "Edge radial electric field studies via charge exchange recombination spectroscopy on the Alcator C-Mod Tokamak." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54462.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 189-197).
It is commonly accepted that ExB velocity shear is responsible for the suppression of edge turbulence, which reduces the losses of both energy and particles across magnetic field lines and results in the formation of edge transport barriers and high-confinement mode (H-mode) in tokamak plasmas. However, the self consistent evolution of the radial electric field profile (Er), pedestal shape and improvement in plasma confinement is not well understood. A better understanding of pedestal physics and the interplay between Er, turbulence suppression and pedestal formation should enable better control of edge transport and improve core confinement. A new, high-resolution, charge exchange recombination spectroscopy (CXRS) diagnostic has been installed on Alcator C-Mod to provide measurements of the B5+ population in the pedestal region. This diagnostic is capable of measuring the boron temperature, density, and poloidal and toroidal velocity with 3mm radial resolution and 5ms temporal resolution. These profiles, coupled with knowledge of the toroidal and poloidal magnetic fields, enable the determination of the edge radial electric field through the radial force balance equation. The new CXRS diagnostic has provided the first spatially resolved calculations of the radial electric field in the C-Mod edge and has made possible significant contributions to the study of pedestal physics. Detailed measurements of the boron population have been made in a variety of plasma regimes. The measured rotation profiles connect the SOL and core measurements and are consistent with both. The CXRS boron temperature profiles are observed to agree well with the Thomson Scattering electron temperature profiles in bothl shape and magnitude over a wide range of collisionalities. In H-mode plasmas both the boron temperature and density profiles form clear pedestals, similar to what is observed in the electron channel. The edge toroidal rotation increases in the concurrent direction at the onset of H-mode confinement and the poloidal rotation in the pedestal region increases in the electron diamagnetic direction forming a narrow
(cont.) peak (3-4mm) just inside of the LCFS. In Ohmic L-mode plasmas Er is positive near the last closed flux surface (LCFS) and becomes more negative with distance into the plasma. In H-mode plasmas E, is positive in the core, but forms a deep negative well, relative to its L-mode values, just inside of the LCFS. These results are qualitatively consistent with the observations made on other machines. However, the C-Mod H-mode Er wells are unprecedeited in depth (up to 300kV/m) and the narrow E, well widths (5mm), as compareJ to results from other tokamaks, suggest a scaling with machine size. The measured Er well widths have been compared to theoretical scalings for the edge pedestal and no significant correlation was observed with any of the predictions. In fact, very little variation of the E, well width is observed in general. Howc:ver, the depth of the E, well, or alternatively the magnitude of the E, shear (constant width), shows a strong correlation with improved plasma energy confinement. It also correlates well with the edge electron temperature and pressure pedestal heights (and gradients). It is not, however, very sensitive to variation in the edge electron density pedestal height. These results are an indication that the energy and particle transport have different relationships to Er, with energy transport more directly linked. The radial electric field results from ELM-free H-mode and I-mode plasmas support this interpretation.
by Rachael Marie McDermott.
Ph.D.
Kumar, Santhosh Tekke Athayil, and santhosh kumar@anu edu au. "Experimental Studies of Magnetic Islands, Configurations and Plasma Confinement in the H-1NF Heliac." The Australian National University. Research School of Physical Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20080611.171513.
Full textWrench, Christopher G. "Collisional transport of trace impurity ions and the role of the radial electric field in spherical tokamak plasmas." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/55347/.
Full textCavedon, Marco [Verfasser], Ulrich [Akademischer Betreuer] [Gutachter] Stroth, and Aliaksandr [Gutachter] Bandarenka. "The role of the radial electric field in the development of the edge transport barrier in the ASDEX Upgrade tokamak / Marco Cavedon. Betreuer: Ulrich Stroth. Gutachter: Aliaksandr Bandarenka ; Ulrich Stroth." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1103135260/34.
Full textVidal, Denis Tadeu Rajh. "Elaboração de um sistema de controle externo do fluxo eletrosmótico para eletroforese capilar com detecção condutométrica sem contato." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-21072008-151809/.
Full textThis work presents the implementation, in an equipment for capillary electrophoresis (CE) with contactless conductivity detection (C4D), of a system for external control of the electroosmotic flow (EOF) via external radial voltage (Vrad). Through external potential, directly applied to the capillary, the electroosmotic flow can be controlled, because this practice couples the applied external potential to the zeta potential through the buffer solution within the capillary. The use of the technique allowed the baseline resolution of two amino acids (Leucine and Isoleucine), whose mobilities differ only by 0,12 cm2.V-1.s-1, using acetic acid 500 mmol.L-1 at pH = 2,55 as the running electrolyte. The approach, called \"infinite capillary column\", consists in successive reversals in the direction of the EOF, trapping species within the capillary column with electrophoretic mobility smaller than the EOF mobility. Thus, the two amino acids were retained by a period of approximately 120 minutes in the capillary that was enough to promote the baseline resolution. Previous works describe that the reversion of the EOF becoming more difficult as pH increases. In order to achieve a more effective control of EOF at high pH values (limiting the technique to a narrow performance band), tests were carried out in electrolytes containing flow reversing agents such as CTAB, CaCI2 and BaCI2. These additives were used at very low concentrations, which kept the normal direction of EOF, and the use of such agents had only the purpuse of reducing the density of silanolate groups in solutions of pH above 6,0. This approach allowed the reversion of the EOF using MES/HIS buffer, which pH was 6,1. Finally, this research has generated an interesting perspective about the possibility of finding combinations of electrolytes and surfactants aiming the Vrad range´s extension at high pH values.
Carpenter, Joanna Katharine Hicks. "Magnetic field effects on electron transfer reactions in photosynthetic bacteria." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390466.
Full textScharfe, Michelle Kristin. "Electron cross field transport modeling in radial-axial hybrid hall thruster simulations /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full textEveson, Robert W. "Geminate free radical processes and magnetic field effects." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325978.
Full textWagner-Rundell, Nicola. "Electron spin relaxation effects on radical recombination reactions in weak magnetic fields." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497470.
Full textGravestijn, Bob. "Importance of radial profiles in spectroscopic diagnostics applied to the EXTRAP-T2R reversed-field pinch." Doctoral thesis, KTH, Physics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3656.
Full textThe determination of the plasma confinement propertiesdemand data as the electron temperature, the ionic and electrondensity profiles and the radiative emissivity profiles. Thefocus of this thesis is the importance of radial profiles inspectroscopic diagnostics applied to the EXTRAP-T2Rreversed-field pinch.
EXTRAP-T2R is a resistive shell reversed-field pinch with amagnetic field shell penetration time much longer than therelaxation cycle time scale. Significant improvements inconfinement properties derived by quantitative plasmaspectroscopy in the vacuum ultraviolet are observed compared tothe previous device EXTRAP-T2. The low level of magneticturbulence and the good magnetic surfaces in the edge regionexplain this observed improvement. A current profile controlexperiment reduces the stochastic transport, which is connectedto the dynamo, and improves the confinement in EXTRAP-T2R evenmore.
A comparison of the electron temperature estimated by usinga ratio of line intensities from the same ionization stage ofoxygen and the Thomson scattering system shows that thedifference is explained by the different spatial dependence ofthe excited state populations and the corresponding emissivityof these spectral lines. A collisional radiative model givesestimates for radial profiles of impurities which are notmeasured in EXTRAP-T2R. The estimated profiles can in turn beused to determine the radial profile of the effective ioncharge, the emissivity and finally the radiative power. Asinput, the model uses radial profiles.
Neutral hydrogen is predominantly present in the boundaryregion of the plasma. Spectroscopic investigations in this areashow very asymmetric spectral lines of hydrogen due to themovement of atoms. The velocity of the hydrogen atoms dependson the type of plasma-wall interaction and their measurementhelps to identify the different interaction processes. Theexistence of hydrogen molecules in the edge complicates theinterpretation of the line shapes and on the determination ofthe particle confinement time.
Keywords:Reversed-field pinch, EXTRAP-T2R, quantitativeplasma spectroscopy, VUV spectroscopy, line-integrated electrontemperature, oxygen, profiles, confinement properties, powerbalance, hydrogen, particle confinement time.
Yeung, David. "Dual-tuned radiofrequency coils for field-cycled proton-electron double resonance imaging of free radicals." Thesis, University of Aberdeen, 1995. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU078721.
Full textShtogun, Yaroslav. "Properties of Carbon Nanotubes Under External Factors: Adsorption, Mechanical Deformations, Defects, and External Electric Fields." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1771.
Full textShet, Keerthi Vishnudas. "Development Of Instrumentation And Techniques To Adapt Proton Electron Double Resonance Imaging For Biomedical Imaging." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1227731151.
Full textLejosne, Solène. "Modélisation du phénomène de diffusion radiale au sein des ceintures de radiation terrestres par technique de changement d’échelle." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0027/document.
Full textThis study falls within the field of the Earth’s radiation belt dynamics. It consists of modelingthe radial diffusion process based on a spatiotemporal resolution higher than the resolution atwhich radiation belt dynamics are described in terms of a diffusion equation. The approachhas been organized in three parts. First, we described radial diffusion theoretically,highlighting the main drivers of the phenomenon and giving a ready-made formula of theradial diffusion coefficients. Then, based on this formula, we aimed to quantify the radialdiffusion coefficients. In order to reach this goal, we developed analytical and numericalprocedures, and then, observational procedures. Finally, we discussed the results and the prosand cons of each method. This study highlights the central role of asymmetric variations ofthe electromagnetic fields and induced electric fields in the driving of the intensity of theradial diffusion process. It provides tracks for numerical and experimental quantification ofthese two drivers. It also provides tools for a critical review of the literature. It paves the wayfor a more accurate determination of radial diffusion coefficients based on a more precisedescription of the electromagnetic environment and its variations
Wieland, Bernd [Verfasser], Sibylle [Akademischer Betreuer] Günter, and Peter A. [Akademischer Betreuer] Feulner. "Investigations on radial electric fields in the edge transport barrier of H-mode discharges / Bernd Wieland. Gutachter: Sibylle Günter ; Peter A. Feulner. Betreuer: Sibylle Günter." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1015627889/34.
Full textNick, Thomas Udo. "Hydrogen Bonds and Electrostatic Environment of Radical Intermediates in Ribonucleotide Reductase Ia." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-877F-7.
Full textLoridan, Vivien. "Physical and numerical modeling of the dynamics of high-energy electrons trapped in the outer radiation belt of the Earth’s magnetosphere." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLN043/document.
Full textSatellites are vulnerable to high-energy particles trapped in the Van Allen belts. To ensure their protection, it is necessary to predict properly the electron dynamics in the magnetosphere. We first propose an original method to find the analytical solution of the reduced Fokker-Planck equation that models the transport and loss of electrons in the inner magnetosphere. The resolution relies on an eigenfunction expansion approach. If the analytical solution is proven to be useful at uncovering some of the physical properties of the radiation belts, it is also relevant to validate the numerical code that solves the reduced Fokker-Planck equation, which has been developed during the PhD. The latter code is used to generalize the previous study in illustrating the evolution of the electron fluxes for various energies and locations. We demonstrate that the structure of the radiation belts as well as their dynamical timescales only depend on a few well-chosen parameters. In the perspective of reproducing a specific storm-recovery event reported by the NASA Van Allen Probes, we are able to simulate the electron scattering in the Earth’s atmosphere due to the interaction with magnetospheric electromagnetic waves. The consideration of data-driven and event-specific conditions enables us to corroborate the observed fluxes. Finally, various influences of the Earth’s magnetic field on the dynamics of the radiation belts are investigated. We focus on the outer belt to see how the magnetic field asymmetries, which are strongly shaped by solar activity, affect the way of conciliating theory and observations. We also explore the importance of new hidden diffusive processes that emerge due to the natural irregularity of the magnetic field in the closest vicinity of the Earth
Richard, Cyril. "Spectroscopie électronique et effet zeeman dans le radical NiH." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00595685.
Full textPooam, Marootpong. "The biological effects of applied magnetic fields on cryptochrome and response." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS062.
Full textCryptochromes are highly conserved blue-light-absorbing flavoproteins that have been linked to the perception of electromagnetic stimuli in numerous organisms. We mainly studied the mechanism for the interaction between magnetic fields and cryptochromes in the context of the radical-pair theory. We investigated the response of Arabidopsis cryptochrome-1 in vivo to a static magnetic field. The biological activities of cryptochrome were enhanced by the magnetic field. Interestingly, the effects of the magnetic fields could be observed even the magnetic field was given exclusively during dark intervals between light exposures. This finding indicated that the magnetically sensitive reaction step in the cryptochrome photocycle must occur during flavin reoxidation. Moreover, we also used frequency (RF) stimulated to Arabidopsis cryptochrome as the diagnostic tools to confirm the radical-pair hypothesis. In the study, we found a disruptive effect of RF on the activity of cryptochrome. Our findings could confirm the occurrence of the radical-pair mechanism and the involvement of cryptochrome for magnetoreception. Additionally, we also showed a disruptive effect of the low-level static magnetic field (LLF) condition where the external magnetic fields were almost eliminated. The result of this condition was consistent with the effect of RF exposure. Furthermore, we also reported that LLF could increase the expression of some PEMF-induced genes in human cells. This finding could provide the evidence to support the effect of magnetic, not induced electric fields in human physiology
Kumar, Santhosh Tekke Athayil. "Experimental Studies of Magnetic Islands, Configurations and Plasma Confinement in the H-1NF Heliac." Phd thesis, 2007. http://hdl.handle.net/1885/49287.
Full textArgirevic, Tomislav. "High-field EPR and ENDOR spectroscopy for proton-coupled electron transfer investigations in E.coli ribonucleotide reductase." Doctoral thesis, 2011. http://hdl.handle.net/11858/00-1735-0000-0006-B09C-C.
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