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Review of D-T Experiments Relevant to Burning Plasma Issues

Description: Progress in the performance of tokamak devices has enabled not only the production of significant bursts of fusion energy from deuterium-tritium (D-T) plasmas in the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET) but, more importantly, the initial study of the physics of burning magnetically confined plasmas. The TFTR and JET, in conjunction with the worldwide fusion effort, have studied a broad range of topics including magnetohydrodynamic stability, transport, wave-part… more
Date: December 21, 2001
Creator: Hawryluk, R.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Small-action Particles in a Tokamak in the Presence of an n = 1 Mode

Description: It is found that an m = n = 1 mode with the amplitude exceeding a certain threshold can lead to stochastic motion of energetic ions in tokamaks, the large orbit width particles (potatoes) being most easily affected. An n = 1 mode can redistribute particles also in the absence of stochasticity but only when the perturbation is quickly switched on/off, e.g., due to sawtooth crash. In the latter case, the perturbation results in regular motion of particles around a certain helical orbit, at which … more
Date: November 1, 1999
Creator: White, R. B.; Lutsenko, V. V.; Kolesnichenko, Ya. I. & Yakovenko, Yu. V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Toroidal Gyrofluid Equations for Simulations of Tokamak Turbulence

Description: A set of nonlinear gyrofluid equations for simulations of tokamak turbulence are derived by taking moments of the nonlinear toroidal gyrokinetic equation. The moment hierarchy is closed with approximations that model the kinetic effects of parallel Landau damping, toroidal drift resonances, and finite Larmor radius effects. These equations generalize the work of Dorland and Hammett [Phys. Fluids B 5, 812 (1993)] to toroidal geometry by including essential toroidal effects. The closures for phas… more
Date: April 1, 1996
Creator: Beer, M. A. & Hammett, G. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Review of recent experiments on magnetic reconnection in laboratory plasmas

Description: The present paper reviews recent laboratory experiments on magnetic reconnection. Examples will be drawn from electron current sheet experiments, merging spheromaks, and from high temperature tokamak plasmas with the Lundquist numbers exceeding 10{sup 7}. These recent laboratory experiments create an environment which satisfies the criteria for MHD plasma and in which the global boundary conditions can be controlled externally. Experiments with fully three dimensional reconnection are now possi… more
Date: February 1, 1995
Creator: Yamada, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Potential of commercial tokamak reactors with improved physics

Description: The impact of improvements in plasma confinement and beta on commercial tokamak embodiments has been systematically investigated. Cases were investigated for both steady-state and pulsed reactors. A narrow range of useful confinement enhancement (H factors over the ITER-89 Power scaling) and Troyon beta limit coefficients g are found to be beneficial for reducing the cost of electricity (COE). Improvements in the beta limit (i.e., g) offer the greatest improvement in reactors. For g limited to … more
Date: November 1, 1993
Creator: Galambos, J. D.; Perkins, L. J.; Haney, S. & Mandrekas, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department

Next Generation Friction Stir Welding Tools for High Temperature Materials

Description: The historical success of friction stir welding (FSW) on materials such as aluminum and magnesium alloys is associated with the absence of melting and solidification during the solid-state process. However, commercial adoption of FSW on steels and other non-ferrous high-strength, high-temperature materials such as nickel-base and titanium-base alloys is limited due to the high costs associated with the process. In this dissertation, the feasibility of using an FSW approach to fabricate certain … more
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Date: July 2023
Creator: Gaddam, Supreeth
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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EXPLICT CALULATIONS OF HOMOCLINIC TANGLES SURROUNDING MAGNETIC ISLANDS IN TOKAMAKS

Description: We present explicit calculations of the complicated geometric objects known as homoclinic tangles that surround magnetic islands in the Poincare mapping of a tokamak's magnetic field. These tangles are shown to exist generically in the magnetic field of all toroidal confinement systems. The geometry of these tangles provides an explanation for the stochasticity known to occur near the X-points of the Poincare mapping. Furthermore, the intersection of homoclinic tangles from different resonances… more
Date: June 1, 2002
Creator: Roeder, R. K. W.; Rapoport, B. I. & Evans, T. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Formation and Sustainment of a Very Low Aspect Ratio Tokamak Using Coaxial Helicity Injection (the Helicity Injected [HIT] Experiment). Annual Progress Report No. 5, December 1, 1993--December 31, 1994

Description: This is the fifth Progress Report on the Helicity Injected Tokamak (HIT) at the University of Washington, Seattle, DOE Grant DE-FE06-90ER54095. This report covers the period of December 1, 1993 through December 31.
Date: February 6, 1995
Creator: Jarboe, T. R. & Nelson, B. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Shear flow effects on ion thermal transport in tokamaks

Description: From various laboratory and numerical experiments, there is clear evidence that under certain conditions the presence of sheared flows in a tokamak plasma can significantly reduce the ion thermal transport. In the presence of plasma fluctuations driven by the ion temperature gradient, the flows of energy and momentum parallel and perpendicular to the magnetic field are coupled with each other. This coupling manifests itself as significant off-diagonal coupling coefficients that give rise to new… more
Date: March 1, 1995
Creator: Tajima, T.; Horton, W.; Dong, J.Q. & Kishimoto, Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Shear Flow Effects on Resistive Ballooning Turbulence

Description: Resistive ballooning modes could be responsible for the turbulence and induced transport observed at the edge of present tokamaks. Due to the mode structure, the geometry of the calculation is fully toroidal. The increase in computer capabilities allows now high resolution turbulence calculations. This is very important in the case of ballooning modes since the spectrum is very flat. Two main issues are addressed in this paper: (1) The validity of the mixing length approach for toroidal modes. … more
Date: December 31, 1997
Creator: Garcia, L.; Carreras, B. A. & Lynch, V. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Design assumptions and bases for small D-T-fueled Sperical Tokamak (ST) fusion core

Description: Recent progress in defining the assumptions and clarifying the bases for a small D-T-fueled ST fusion core are presented. The paper covers several issues in the physics of ST plasmas, the technology of neutral beam injection, the engineering design configuration, and the center leg material under intense neutron irradiation. This progress was driven by the exciting data from pioneering ST experiments, a heightened interest in proof-of-principle experiments at the MA level in plasma current, and… more
Date: December 31, 1996
Creator: Peng, Y. K. M.; Galambos, J. D. & Fogarty, P. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Survey of electric field shear driven by radio frequency waves in tokamak plasmas

Description: The stabilization of plasma turbulence by sheared poloidal rotation is thought to explain enhanced confinement in tokamak plasmas. One method proposed for controlling sheared flow is the use of externally driven radio-frequency (RF) waves. A number of calculations and some experiments have suggested that a modest amount of power in the ion cyclotron range of frequencies (ICRF) can drive the needed flows. Previous calculations have relied on incompressible fluid models which balance RF forces in… more
Date: November 1, 1998
Creator: Jaeger, E. F.; Berry, L. A. & Batchelor, D. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A hybrid digital-analog long pulse integrator

Description: A digital-analog integrator has been developed for use with inductive magnetic sensors in long-pulse tokamaks. Continuous compensation of input offsets is accomplished by alternating analog-to-digital convertor samples from the sensor and a dummy load, while an RC network provides passive integration between samples. Typically a sampling rate of 10 kHz is used. In operational tests on the DIII-D tokamak, digital and analog integration of tokamak data show good agreement. The output drift error … more
Date: May 1, 1996
Creator: Strait, E. J.; Broesch, J. D.; Snider, R. T. & Walker, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Stability of the toroidicity-induced Alfven eigenmodes in JT-60U ICRF experiments

Description: It is shown that the stability of toroidicity-induced Alfven eigenmodes (TIE) in JT-60U ICRF experiments is strongly dependent on mode location. This dependence results in sequential excitation of high-n TIE modes as the central safety factor, q, drops in time.
Date: April 1, 1996
Creator: Fu, G. Y.; Cheng, C. Z.; Kimura, H.; Ozeki, T. & Saigusa, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A study of tearing modes via electron cyclotron emission from tokamak plasmas

Description: This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode struc… more
Date: July 1, 1998
Creator: Ren, C.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Electron cyclotron heating and current drive approach for low-temperature startup plasmas using O-X-EBW mode conversion

Description: A mechanism for heating and driving currents in very overdense plasmas is considered based on a double-mode conversion: Ordinary mode to Extraordinary mode to electron Bernstein wave. The possibility of using this mechanism for plasma buildup and current ramp in the National Spherical Torus Experiment is investigated.
Date: June 1, 1997
Creator: Batchelor, D.B. & Bigelow, T.S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Thermal ablation of plasma-facing surfaces in tokamak disruptions: Sensitivity to particle kinetic energy

Description: Ablation damage to solid targets with high heat flux impulses is generally greater high-energy electron beam heat sources compared to low-energy plasma guns. This sensitivity to incoming particle kinetic energy is explored with computer modelling; a fast-running routine (DESIRE) is developed for initial scoping analysis and is found to be in reasonable agreement with several experiments on graphite and tungsten targets. If tokamak disruptions are characterized by particle energies less than {ap… more
Date: February 1, 1996
Creator: Ehst, D.A. & Hassanein, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High Beta Tokamaks

Description: Perhaps the ideal tokamak would have high {beta} ({beta} {approx}> 1) and classical confinement. Such a tokamak has not been found, and we do not know if one does exist. We have searched for such a possibility, so far without success. In 1990, we obtained analytic equilibrium solutions for large aspect ratio tokamaks at {beta} {approx} {Omicron}(1) [1]. These solutions and the extension at high {beta} poloidal to finite aspect ratio [2] provided a basis for the study of high {beta} tokamaks.… more
Date: November 14, 1998
Creator: Cowley, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The ion cyclotron system for the KSTAR tokamak

Description: The KSTAR (Korean Superconducting Tokamak Advanced Research) tokamak (Ro = 1.8 m, a = 0.5 m, {kappa} {lt}= 2, BT{lt}= 3.5 T, Ip {lt}= 2 MA, {tau} pulse {lt}= 300 s) is being constructed to do long pulse, high beta, advanced operating mode fusion physics experiments. The ion cyclotron (IC) system (in conjunction with an 8-MW neutral beam and a 1.5-MW lower hybrid system) will provide heating and current drive capability for the machine. The IC system will deliver 6 MW of rf power to the plasma i… more
Date: January 1, 1998
Creator: Swain, D. W.; Ryan, P. W.; Taylor, D. J.; Hong, B. G.; Bae, Y. D. & Hwang, C. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Interchange and Infernal Fishbone Modes in Plasmas with Tangentially Injected Beams

Description: New energetic particle mode instabilities of fishbone type are predicted. The considered instabilities are driven by the circulating energetic ions. They can arise in plasmas of tokamaks and spherical tori with weak magnetic shear in the wide core region and strong shear at the periphery, provided that the central safety factor is close to the ratio m/n, where m and n are the poloidal mode number and toroidal mode number, respectively. The instability with m = n = 1 has interchange-like spatial… more
Date: January 1, 2006
Creator: Kolesnichenko, Ya I.; Marchenko, V. S. & White, R. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The use of iron shims to reduce the toroidal field ripple in Tokamaks

Description: A study was performed to investigate the use of laminated ferromagnetic material, iron shims, to reduce the toroidal field, TF, ripple in Tokamaks. Fixed geometry shims can reduce the TF ripple and will behave linearly for Low Field Tokamaks with central fields under 2 Tesla. For High Field Tokamaks with central fields under 6 Tesla, fixed geometry shims can reduce the TF ripple but will have some non-linear behavior. Variable geometry shims can reduce the field ripple significantly with comple… more
Date: February 1, 1993
Creator: Sheffield, G. V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A Class of High Ebp Equilibria in Strongly Finite Aspect Ratio Tokamak Plasmas

Description: OAK B202 A CLASS OF HIGH EBP EQUILIBRIA IN STRONGLY FINITE ASPECT RATIO TOKAMAK PLASMAS. A class of very high poloidal beta ({beta}{sub p}) equilibria is exhibited in which {var_epsilon}{beta}{sub p} ({var_epsilon} is the inverse aspect ratio) exceeds analytic equilibrium limits previously anticipated from simplified large aspect ratio models, as well as previous experimental equilibrium limits. The extension in these limits is shown to be due to a combination of finite aspect ratio effects and… more
Date: August 1, 2002
Creator: Lin-Liu, Y. R.; Turnbull, A. D.; Miller, R. L.; Chan, V. S. & Politzer, P. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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