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Orbit width scaling of TAE instability growth rate

Description: The growth rate of Toroidal Alfven Eigenmodes (TAE) driven unstable by resonant coupling of energetic charged particles is evaluated in the ballooning limit over a wide range of parameters. All damping effects are ignored. Variations in orbit width, aspect ratio, and the ratio of alfven velocity to energetic particle birth velocity, are explored. The relative contribution of passing and trapped particles, and finite Larmor radius effects, are also examined. The phase space location of resonant particles with interact strongly with the modes is described. The accuracy of the analytic results with respect to growth rate magnitude and parametric dependence is investigated by comparison with numerical results.
Date: July 1, 1995
Creator: Wong, H.V.; Berk, H.L. & Breizman, B.N.
Partner: UNT Libraries Government Documents Department

Heating and current drive on NSTX and HHFW experiments on CDX-U

Description: The NSTX (National Spherical Torus Experiment) device to be built at Princeton is a low-aspect-ratio toroidal device that has the achievement of high toroidal beta ({approximately} 45%) and noninductive operation as two of its main research goals. To achieve these goals, significant auxiliary-heating and current-drive systems are required. Present plans include ECH (electron cyclotron heating) for preionized and start-up assist, HHFW (high harmonic fast wave) for heating and current drive, and, eventually, NBI (neutral-beam injection) for heating, current drive and plasma rotation. In support of the NSTX program, experimental tests of HHFW physics have been performed on the Current Drive Experiment-Upgrade (CDX-U).
Date: July 1, 1998
Creator: Wilson, J.R.; Hosea, J. & Grisham, L.
Partner: UNT Libraries Government Documents Department

Plasma confinement theory and transport simulation

Description: The objectives continue to be: (1) to advance the transport studies of tokamaks, including development and maintenance of the Magnetic Fusion Energy Database, and (2) to provide theoretical interpretation, modeling and equilibrium and stability for TEXT-Upgrade. Recent publications and reports, and conference presentations of the Fusion Research Center theory group are listed.
Date: February 1, 1993
Creator: Ross, D.W.
Partner: UNT Libraries Government Documents Department

Soft x-ray imaging system for measurement of noncircular tokamak plasmas

Description: A soft x-ray camera and image processing system has been constructed to provide measurements of the internal shape of high temperature tokamak plasmas. The camera consists of a metallic-foil-filtered pinhole aperture and a microchannel plate image intensifier/convertor which produces a visible image for detection by a CCD TV camera. A wide-angle tangential view of the toroidal plasma allows a single compact camera to view the entire plasma cross section. With Be filters 12 to 50 ..mu..m thick, the signal from the microchannel plate is produced mostly by nickel L-line emissions which orignate in the hot plasma core. The measured toroidal image is numerically inverted to produce a cross-sectional soft x-ray image of the plasma. Since the internal magnetic flux surfaces are usually isothermal and the nickel emissivity depends strongly on the local electron temperature, the x-ray emission contours reflect the shape of the magnetic surfaces in the plasma interior. Initial results from the PBX tokamak experiment show clear differences in internal plasma shapes for circular and bean-shaped discharges.
Date: August 1, 1986
Creator: Fonck, R.J.; Reusch, M.; Jaehnig, K.P.; Hulse, R. & Roney, P.
Partner: UNT Libraries Government Documents Department

Engineering, safety, and economic evaluations of ASPIRE (Advanced Safe Pool Immersed REactor)

Description: A preconceptual design of a tokamak fusion reactor concept called ASPIRE (Advanced Safe Pool Immersed REactor) has been developed. This concept provides many of the attractive features that are needed to enhance the capability of fusion to become the power generation technology for the 21st century. Specifically, these features are: inherent safety, low pressure, environmental compatibility, moderate unit size, high availability, high thermal efficiency, simplicity, low radioactive inventory, Class C radioactive waste disposal, and low cost of electricity. We have based ASPIRE on a second stability tokamak. However, the concept is equally applicable to a first stability tokamak or to most other magnetic fusion systems.
Date: February 1, 1988
Creator: Sze, D.K.; Gordon, J.; Piet, S.; Cheng, E.T. & Klein, A.
Partner: UNT Libraries Government Documents Department

The ARIES-III D- sup 3 He tokamak reactor: Design-point determination and parametric studies

Description: The multi-institutional ARIES study has generated a conceptual design of another tokamak fusion reactor in a series that varies the assumed advances in technology and physics. The ARIES-3 design uses a D-{sup 3}He fuel cycle and requires advances in technology and physics for economical attractiveness. The optimal design was characterized through systems analyses for eventual conceptual engineering design. Results from the systems analysis are summarized, and a comparison with the high-field, D-T fueled ARIES-1 is included. 11 refs., 5 figs.
Date: January 1, 1991
Creator: Bathke, C.G.; Werley, K.A.; Miller, R.L.; Krakowski, R.A. (Los Alamos National Lab., NM (United States)) & Santarius, J.F. (Wisconsin Univ., Madison, WI (United States))
Partner: UNT Libraries Government Documents Department

Arcing phenomena in fusion devices workshop

Description: The workshop on arcing phenomena in fusion devices was organized (1) to review the pesent status of our understanding of arcing as it relates to confinement devices, (2) to determine what informaion is needed to suppress arcing and (3) to define both laboratory and in-situ experiments which can ultimately lead to reduction of impurities in the plasma caused by arcing. The workshop was attended by experts in the area of vacuum arc electrode phenomena and ion source technology, materials scientists, and both theoreticians and experimentalists engaged in assessing the importance of unipolar arcing in today's tokamaks. Abstracts for papers presented at the workshop are included.
Date: January 1, 1979
Creator: Clausing, R.E.
Partner: UNT Libraries Government Documents Department

Logical and physical database design within a full-text environment

Description: This paper describes the problems and solutions encountered in the design of logical and physical data bases within a full-text environment. A full-text environment can be defined as data bases that store both citation information as well as actual document text. The problems/solutions encountered were a result of the necessity to integrate distinct physical data bases into a single logical data base without the assistance of a Data Base Management System that is capable of physical data base integration.
Date: January 1, 1985
Creator: Michelsen, C.D. & Shafer, D.F.
Partner: UNT Libraries Government Documents Department

Multiple mode model of tokamak transport

Description: Theoretical models for radical transport of energy and particles in tokamaks due to drift waves, rippling modes, and resistive ballooning modes have been combined in a predictive transport code. The resulting unified model has been used to simulate low confinement mode (L-mode) energy confinement scalings. Dependence of global energy confinement on electron density for the resulting model is also described. 26 refs., 1 fig., 2 tabs.
Date: July 1, 1989
Creator: Singer, C.E.; Ghanem, E.S.; Bateman, G. & Stotler, D.P.
Partner: UNT Libraries Government Documents Department

The modification of turbulent transport by orbit averaging

Description: The effect on plasma turbulence of orbit averaging by thermal ions is considered, and illustrated for two modes of potential importance for tokamaks. The effect can reduce the ion response below that in earlier treatments, modifying the predicted mode growth rate, which in turn modifies the turbulent transport. For both modes, the effect modifies earlier transport expressions with a neoclassical factor,'' which makes the scalings of the resultant transport coefficients with plasma current and magnetic field closer to those found experimentally. Additionally, for the trapped electron mode, this mechanism provides a potential explanation of the observed more favorable scaling of {chi}{sub i} with T{sub i} in supershots than in L-modes. 21 refs., 2 figs.
Date: May 1, 1991
Creator: Mynick, H.E. & Zweben, S.J.
Partner: UNT Libraries Government Documents Department

Stellarator approach to toroidal plasma confinement

Description: An overview is presented of the development and current status of the stellarator approach to controlled thermonuclear confinement. Recent experimental, theoretical, and systems developments have made this concept a viable option for the evolution of the toroidal confinement program. Some experimental study of specific problems associated with departure from two-dimensional symmetry must be undertaken before the full advantages and opportunities of steady-state, net-current-free operation can be realized.
Date: December 1, 1981
Creator: Johnson, J.L.
Partner: UNT Libraries Government Documents Department

Stellarator program

Description: The worldwide development of stellarator research is reviewed briefly and informally.
Date: August 1, 1981
Creator: Johnson, J.L.; Grieger, G.; Lees, D.J.; Rabinovich, M.S.; Shohet, J.L. & Uo, K.
Partner: UNT Libraries Government Documents Department

Linear oscillations in general magnetically confined plasmas. ARMOR RADIUS; MAGNETIC FIELD CONFIGURATIONS; WAVE PROPAGATION

Description: A systematic formalism for investigating linear electromagnetic perturbations in general magnetic field configurations is developed. The formalism employs the small adiabaticity parameter rho/L/sub 0/ and is valid for arbitrary frequencies. Here, rho and L/sub 0/ are, respectively, the Larmor radius and equilibrium scale length. Effects associated with plasma and magnetic field inhomogeneities as well as finite Larmor radii are contained. The specific case of axisymmetric tokamaks is then considered to illustrate the potential application.
Date: April 1, 1982
Creator: Chen, L. & Tsai, S.T.
Partner: UNT Libraries Government Documents Department

Effect of the aspect ratio on the stability limits of TJ-II-like stellarators

Description: The four-field-period device TJ-II has a major radius of 1.5 m and an average plasma radius of 0.10--0.25 m, with a typical plasma aspect ratio A{sub P} of 10. In the infinite aspect ratio, helically symmetric limit, the region of the stability to low-n modes has been shown to extend to average betas of at least 40%, for a relatively highly indented plasma. It is possible to approximate the helically symmetric limit from the actual TJ-II parameters increasing the number of toroidal periods N{sub T} and choosing the major radius R{sub O} such as to obtain a constant helical pitch h = N{sub T}/R{sub O}. In this way the aspect ratio per period is fixed. In this work we analyze a shear-less TJ-II configuration with a rotational transform per period of 0.36 and a vacuum magnetic well of 3.5%. By taking for N{sub T} the values N{sub T} = 3, 4, 5, 8, 10, 11, 12, 19 and 100 a sequence of equilibria is generated. These equilibria are calculated with the fixed boundary version of the VMEC code. The Mercier stability properties are then analyzed.
Date: January 1, 1991
Creator: Varias, A.; Alvarez, A.; Fraguas, A.L.; Alejaldre, C. (Association Euratom-Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain)); Dominguez, N.; Carreras, B.A. et al.
Partner: UNT Libraries Government Documents Department

Comments on ''theory of dissipative density-gradient-driven turbulence in the tokamak edge'' (Phys. Fluids 28, 1419 (1985))

Description: The author critiques the model of tokamak edge turbulence by P.W. Terry and P.H. Diamond (Phys. Fluids 28, 1419, 1985). The critique includes a discussion of the physical basis, consistency and quantitative accuracy of the Terry-Diamond model. 19 refs. (WRF)
Date: November 1, 1985
Creator: Krommes, J.A.
Partner: UNT Libraries Government Documents Department

The ARIES-I high-field-tokamak reactor: Design-point determination and parametric studies

Description: The multi-institutional ARIES study has examined the physics, technology, safety, and economic issues associated with the conceptual design of a tokamak magnetic-fusion reactor. The ARIES-I variant envisions a DT-fueled device based on advanced superconducting coil, blanket, and power-conversion technologies and a modest extrapolation of existing tokamak physics. A comprehensive systems and trade study has been conducted as an integral and ongoing part of the reactor assessment in order to identify an acceptable design point to be subjected to detailed analysis and integration as well as to characterize the ARIES-I operating space. Results of parametric studies leading to the identification of such a design point are presented. 15 refs., 6 figs., 2 tabs.
Date: January 1, 1989
Creator: Miller, R.L.
Partner: UNT Libraries Government Documents Department

Confinement projections for the Burning Plasma Experiment (BPX)

Description: The mission of the Burning Plasma Experiment (BPX, formerly CIT) is to study the physics of self-heated fusion plasmas (Q = 5 to ignition), and to demonstrate the production of substantial amounts of fusion power (P{sub fus} = 100 to 500 MW). Confinement projections for BPX have been made on the basis of (1) dimensional extrapolation (2) theory-based modeling calibrated to experiment, and (3) statistical scaling from the available empirical data base. The results of all three approaches, discussed in this paper, roughly coincide. We presently view the third approach, statistical scaling, as the most reliable means for projecting the confinement performance of BPX, and especially for assessing the uncertainty in the projection. 11 refs., 2 figs., 1 tab.
Date: January 1, 1991
Creator: Goldston, R.J.; Bateman, G.; Kaye, S.M.; Perkins, F.W.; Pomphrey, N.; Stotler, D.P. et al.
Partner: UNT Libraries Government Documents Department

Optimization of transport in stellarators

Description: Here we relate two stellarator transport optimization schemes to single particle orbits. We also show that reducing transport in the 1/..nu.. regime reduces transport over a much broader range of collisionality. 6 refs., 2 figs.
Date: January 1, 1989
Creator: Hedrick, C.L.; Beasley, C.O. & Van Rij, W.I.
Partner: UNT Libraries Government Documents Department

Ideal low-n and Mercier mode stability boundaries for /ell/ = 2 torsatrons

Description: We studied the relationship between the stability properties of ideal low-n-internal modes and the three-dimensional (3-D) ideal Mercier criterion for /ell/ = 2 torsatron configurations. For the low-n stability studies, we used the stellarator expansion as implemented in the FAR code. The 3-D Mercier criterion was applied to equilibria calculated with the VMEC code. We found that low-n modes with singular surfaces lying in a Mercier region are, in general, unstable and the critical beta given by the Mercier criterion agrees well with the critical beta for the lowest-n unstable mode. This is verified even in the case of global n = 1 modes. Therefore, the 3-D Mercier criterion is a useful guide in mapping the ideal stability beta limits for these torsatron configurations. 5 refs., 5 figs.
Date: January 1, 1989
Creator: Dominguez, N.
Partner: UNT Libraries Government Documents Department

Report of planning workshop on fluctuations and anomalous transport in tokamaks

Description: The workshop was divided into three sections: review of experiments on fluctuations in tokamaks, review of theories of anomalous transport, and discussion of directions for future research and experimental/theoretical collaboration. Each session was assigned a recording secretary to take notes which were used in preparing this report. The report includes the activities, conclusions, and recommendations of the workshop.
Date: October 1, 1982
Partner: UNT Libraries Government Documents Department

Analysis of quench-vent pressures for present design of ITER (International Thermonuclear Experimental Reactor) TF (toroidal field) coils

Description: The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Japan, the European Community, the Union of the Soviet Union, and the United States. This paper examines the effects of a quench within the toroidal field (TF) coils based on current ITER design. It is a preliminary, rough analysis. Its intent is to assist ITER designers while more accurate computer codes are being developed and to provide a check against these more rigorous solutions. Rigorous solutions to the quench problem are very complex involving three- dimensional heat transfer, extreme changes in heat capacities and copper resistivity, and varying flow dynamics within the conductors. This analysis addresses all these factors in an approximate way. The result is much less accurate than a rigorous analysis. Results here could be in error as much as 30 to 40 percent. However, it is believed that this paper can still be very useful to the coil designer. Coil pressures and temperatures vs time into a quench are presented. Rate of helium vent, energy deposition in the coil, and depletion of magnetic stored energy are also presented. Peak pressures are high (about 43 MPa). This is due to the very long vent path length (446 m), small hydraulic diameters, and high current densities associated with ITER's cable-in-conduit design. The effects of these pressures as well as the ability of the coil to be self protecting during a quench are discussed. 3 refs., 1 fig., 3 tabs.
Date: September 20, 1989
Creator: Slack, D.S.
Partner: UNT Libraries Government Documents Department

Comprehensive numerical modelling of tokamaks

Description: We outline a plan for the development of a comprehensive numerical model of tokamaks. The model would consist of a suite of independent, communicating packages describing the various aspects of tokamak performance (core and edge transport coefficients and profiles, heating, fueling, magnetic configuration, etc.) as well as extensive diagnostics. These codes, which may run on different computers, would be flexibly linked by a user-friendly shell which would allow run-time specification of packages and generation of pre- and post-processing functions, including workstation-based visualization of output. One package in particular, the calculation of core transport coefficients via gyrokinetic particle simulation, will become practical on the scale required for comprehensive modelling only with the advent of teraFLOP computers. Incremental effort at LLNL would be focused on gyrokinetic simulation and development of the shell.
Date: January 3, 1991
Creator: Cohen, R.H.; Cohen, B.I. & Dubois, P.F.
Partner: UNT Libraries Government Documents Department