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Chen X, Ruiz JR, Howard NT, Guttenfelder W, Candy J, Hughes JW, Granetz RS, White AE. Feasibility study for a high-k temperature fluctuation diagnostic based on soft x-ray imaging. Rev Sci Instrum 2021; 92:053537. [PMID: 34243288 DOI: 10.1063/5.0043819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/09/2021] [Indexed: 06/13/2023]
Abstract
A new pseudolocal tomography algorithm is developed for soft X-ray(SXR) imaging measurements of the turbulent electron temperature fluctuations (δ Te) in tokamaks and stellarators. The algorithm overcomes the constraints of limited viewing ports on the vessel wall (viewing angle) and limited number of lines of sight (LOS). This is accomplished by increasing the number of LOS locally in a region of interest. Numerical modeling demonstrates that the wavenumber spectrum of the turbulence can be reliably reconstructed, with an acceptable number of viewing angles and LOS and suitable low SNR detectors. We conclude that a SXR imaging diagnostic for measurements of turbulent δ Te using a pseudolocal reconstruction algorithm is feasible.
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Affiliation(s)
- X Chen
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA
| | - J Ruiz Ruiz
- Department of Physics, University of Oxford, Oxford OX1 3NP, United Kingdom
| | - N T Howard
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA
| | - W Guttenfelder
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536, USA
| | - J Candy
- General Atomics, San Diego, California 92127, USA
| | - J W Hughes
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA
| | - R S Granetz
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA
| | - A E White
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA
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2
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Belli EA, Candy J, Waltz RE. Reversal of Simple Hydrogenic Isotope Scaling Laws in Tokamak Edge Turbulence. Phys Rev Lett 2020; 125:015001. [PMID: 32678657 DOI: 10.1103/physrevlett.125.015001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
The role of nonadiabatic electrons in regulating the hydrogenic isotope-mass scaling of gyrokinetic turbulence in tokamak fusion plasmas is assessed in the transition from ion-dominated core transport regimes to electron-dominated edge transport regimes. We propose a new isotope-mass scaling law that describes the electron-to-ion mass-ratio dependence of turbulent ion and electron energy fluxes. The mass-ratio dependence arises from the nonadiabatic response associated with fast electron parallel motion and plays a key role in altering-and in the case of the DIII-D edge, favorably reversing-the naive gyro-Bohm scaling behavior. In the reversed regime hydrogen energy fluxes are larger than deuterium fluxes, which is the opposite of the naive prediction.
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Affiliation(s)
- E A Belli
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - J Candy
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - R E Waltz
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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3
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Jian X, Holland C, Candy J, Belli E, Chan V, Garofalo AM, Ding S. Role of Microtearing Turbulence in DIII-D High Bootstrap Current Fraction Plasmas. Phys Rev Lett 2019; 123:225002. [PMID: 31868395 DOI: 10.1103/physrevlett.123.225002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 10/03/2019] [Indexed: 06/10/2023]
Abstract
We report on the first direct comparisons of microtearing turbulence simulations to experimental measurements in a representative high bootstrap current fraction (f_{BS}) plasma. Previous studies of high f_{BS} plasmas carried out in DIII-D with large radius internal transport barriers (ITBs) have found that, while the ion energy transport is accurately reproduced by neoclassical theory, the electron transport remains anomalous and not well described by existing quasilinear transport models. A key feature of these plasmas is the large value of the normalized pressure gradient, which is shown to completely stabilize conventional drift-wave and kinetic ballooning mode instabilities in the ITB, but destabilizes the microtearing mode. Nonlinear gyrokinetic simulations of the ITB region performed with the cgyro code demonstrate that the microtearing modes are robustly unstable and capable of driving electron energy transport levels comparable to experimental levels for input parameters consistent with the experimental measurements. These simulations uniformly predict that the microtearing mode fluctuation and flux spectra extend to significantly shorter wavelengths than the range of linear instability, representing significantly different nonlinear dynamics and saturation mechanisms than conventional drift-wave turbulence, which is also consistent with the fundamental tearing nature of the instability. The predicted transport levels are found to be most sensitive to the magnetic shear, rather than the temperature gradients more typically identified as driving turbulent plasma transport.
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Affiliation(s)
- X Jian
- University of California, San Diego, La Jolla, California 92093-0417, USA
| | - C Holland
- University of California, San Diego, La Jolla, California 92093-0417, USA
| | - J Candy
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - E Belli
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - V Chan
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - A M Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - S Ding
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA
- Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui, 230031, China
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4
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Ashourvan A, Nazikian R, Belli E, Candy J, Eldon D, Grierson BA, Guttenfelder W, Haskey SR, Lasnier C, McKee GR, Petty CC. Formation of a High Pressure Staircase Pedestal with Suppressed Edge Localized Modes in the DIII-D Tokamak. Phys Rev Lett 2019; 123:115001. [PMID: 31573275 DOI: 10.1103/physrevlett.123.115001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/31/2019] [Indexed: 06/10/2023]
Abstract
We observe the formation of a high-pressure staircase pedestal (≈16-20 kPa) in the DIII-D tokamak when large amplitude edge localized modes are suppressed using resonant magnetic perturbations. The staircase pedestal is characterized by a flattening of the density and temperature profiles in midpedestal creating a two-step staircase pedestal structure correlated with the appearance of midpedestal broadband fluctuations. The pedestal oscillates between the staircase and single-step structure every 40-60 ms, correlated with oscillations in the heat and particle flux to the divertor. Gyrokinetic analysis using the cgyro code shows that when the heat and particle flux to the divertor decreases, the pedestal broadens and the E×B shear at the midpedestal decreases, triggering a transport bifurcation from the kinetic ballooning mode (KBM) to trapped electron mode (TEM) limited transport that flattens the density and temperature profiles at midpedestal and results in the formation of the staircase pedestal. As the heat flux to the divertor increases, the pedestal narrows and the E×B shear at the midpedestal increases, triggering a back transition from TEM to KBM limited transport. The pedestal pressure increases during the staircase phase, indicating that enhanced midpedestal turbulence can be beneficial for confinement.
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Affiliation(s)
- Arash Ashourvan
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - R Nazikian
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - E Belli
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - J Candy
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - D Eldon
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - B A Grierson
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - W Guttenfelder
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - S R Haskey
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - C Lasnier
- Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550, USA
| | - G R McKee
- University of Wisconsin-Madison, 1500 Engineering Dr., Madison, Wisconsin 53706, USA
| | - C C Petty
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
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5
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Wang HQ, Xu GS, Wan BN, Ding SY, Guo HY, Shao LM, Liu SC, Xu XQ, Wang E, Yan N, Naulin V, Nielsen AH, Rasmussen JJ, Candy J, Bravenec R, Sun YW, Shi TH, Liang YF, Chen R, Zhang W, Wang L, Chen L, Zhao N, Li YL, Liu YL, Hu GH, Gong XZ. New edge coherent mode providing continuous transport in long-pulse H-mode plasmas. Phys Rev Lett 2014; 112:185004. [PMID: 24856704 DOI: 10.1103/physrevlett.112.185004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Indexed: 06/03/2023]
Abstract
An electrostatic coherent mode near the electron diamagnetic frequency (20-90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Superconducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond-coated reciprocating probes. The mode propagates in the electron diamagnetic direction in the plasma frame with poloidal wavelength of ∼8 cm. The mode drives a significant outflow of particles and heat as measured directly with the probes, thus greatly facilitating long pulse H-mode sustainment. This mode shows the nature of dissipative trapped electron mode, as evidenced by gyrokinetic turbulence simulations.
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Affiliation(s)
- H Q Wang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - G S Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - B N Wan
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - S Y Ding
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - H Y Guo
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China and General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - L M Shao
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - S C Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - X Q Xu
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E Wang
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N Yan
- Association EURATOM-DTU, Physics Department, DK 2800 Kgs. Lyngby, Denmark
| | - V Naulin
- Association EURATOM-DTU, Physics Department, DK 2800 Kgs. Lyngby, Denmark
| | - A H Nielsen
- Association EURATOM-DTU, Physics Department, DK 2800 Kgs. Lyngby, Denmark
| | - J Juul Rasmussen
- Association EURATOM-DTU, Physics Department, DK 2800 Kgs. Lyngby, Denmark
| | - J Candy
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - R Bravenec
- Fourth State Research, 503 Lockhart Drive, Austin, Texas 78704-4335, USA
| | - Y W Sun
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - T H Shi
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Y F Liang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - R Chen
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - W Zhang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - L Wang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - L Chen
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - N Zhao
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Y L Li
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Y L Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - G H Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - X Z Gong
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
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6
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Staebler GM, Waltz RE, Candy J, Kinsey JE. New paradigm for suppression of gyrokinetic turbulence by velocity shear. Phys Rev Lett 2013; 110:055003. [PMID: 23414026 DOI: 10.1103/physrevlett.110.055003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Indexed: 06/01/2023]
Abstract
The shear in the mean field velocity Doppler shift is shown to suppress the amplitude of electric potential fluctuations by inducing a shift in the peak of the radial wave number spectrum. An analytic model of the process shows that the fluctuation spectrum shifts in the direction where the velocity shear is linearly destabilizing but that nonlinear mixing causes a recentering of the spectrum about a shifted radial wave number at reduced amplitude A model for the 2D nonlinear spectrum is used in a quasilinear calculation of the transport that is shown to accurately reproduce the suppression of energy and particle transport and the Reynolds stress due to the velocity shear.
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Affiliation(s)
- G M Staebler
- General Atomics, P.O. Box 85608, San Diego, California 92186-9784, USA
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7
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Candy J, Belli EA. Neoclassical transport including collisional nonlinearity. Phys Rev Lett 2011; 106:235003. [PMID: 21770513 DOI: 10.1103/physrevlett.106.235003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Indexed: 05/31/2023]
Abstract
In the standard δf theory of neoclassical transport, the zeroth-order (Maxwellian) solution is obtained analytically via the solution of a nonlinear equation. The first-order correction δf is subsequently computed as the solution of a linear, inhomogeneous equation that includes the linearized Fokker-Planck collision operator. This equation admits analytic solutions only in extreme asymptotic limits (banana, plateau, Pfirsch-Schlüter), and so must be solved numerically for realistic plasma parameters. Recently, numerical codes have appeared which attempt to compute the total distribution f more accurately than in the standard ordering by retaining some nonlinear terms related to finite-orbit width, while simultaneously reusing some form of the linearized collision operator. In this work we show that higher-order corrections to the distribution function may be unphysical if collisional nonlinearities are ignored.
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Affiliation(s)
- J Candy
- General Atomics, San Diego, California 92186-5608, USA.
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8
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Guttenfelder W, Candy J, Kaye SM, Nevins WM, Wang E, Bell RE, Hammett GW, LeBlanc BP, Mikkelsen DR, Yuh H. Electromagnetic transport from microtearing mode turbulence. Phys Rev Lett 2011; 106:155004. [PMID: 21568568 DOI: 10.1103/physrevlett.106.155004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Indexed: 05/30/2023]
Abstract
This Letter presents nonlinear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high-β discharge in the National Spherical Torus Experiment. The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free-streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.
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Affiliation(s)
- W Guttenfelder
- Princeton Plasma Physics Laboratory, Princeton New Jersey 08543, USA
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9
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Nevins WM, Wang E, Candy J. Magnetic stochasticity in gyrokinetic simulations of plasma microturbulence. Phys Rev Lett 2011; 106:065003. [PMID: 21405473 DOI: 10.1103/physrevlett.106.065003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Indexed: 05/30/2023]
Abstract
Analysis of the magnetic field structure from electromagnetic simulations of tokamak ion temperature gradient turbulence demonstrates that the magnetic field can be stochastic even at very low plasma pressure. The degree of magnetic stochasticity is quantified by evaluating the magnetic diffusion coefficient. We find that the magnetic stochasticity fails to produce a dramatic increase in the electron heat conductivity because the magnetic diffusion coefficient remains small.
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Affiliation(s)
- W M Nevins
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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10
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Cary JR, Candy J, Cobb J, Cohen RH, Epperly T, Estep DJ, Krasheninnikov S, Malony AD, McCune DC, McInnes L, Pankin A, Balay S, Carlsson JA, Fahey MR, Groebner RJ, Hakim AH, Kruger SE, Miah M, Pletzer A, Shasharina S, Vadlamani S, Wade-Stein D, Rognlien TD, Morris A, Shende S, Hammett GW, Indireshkumar K, Pigarov AY, Zhang H. Concurrent, parallel, multiphysics coupling in the FACETS project. ACTA ACUST UNITED AC 2009. [DOI: 10.1088/1742-6596/180/1/012056] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Casati A, Gerbaud T, Hennequin P, Bourdelle C, Candy J, Clairet F, Garbet X, Grandgirard V, Gürcan OD, Heuraux S, Hoang GT, Honoré C, Imbeaux F, Sabot R, Sarazin Y, Vermare L, Waltz RE. Turbulence in the TORE SUPRA tokamak: measurements and validation of nonlinear simulations. Phys Rev Lett 2009; 102:165005. [PMID: 19518721 DOI: 10.1103/physrevlett.102.165005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Indexed: 05/27/2023]
Abstract
Turbulence measurements in TORE SUPRA tokamak plasmas have been quantitatively compared to predictions by nonlinear gyrokinetic simulations. For the first time, numerical results simultaneously match within experimental uncertainty (a) the magnitude of effective heat diffusivity, (b) rms values of density fluctuations, and (c) wave-number spectra in both the directions perpendicular to the magnetic field. Moreover, the nonlinear simulations help to revise as an instrumental effect the apparent experimental evidence of strong turbulence anisotropy at spatial scales of the order of ion-sound Larmor radius.
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Affiliation(s)
- A Casati
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.
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12
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White AE, Schmitz L, Peebles WA, Carter TA, Rhodes TL, Doyle EJ, Gourdain PA, Hillesheim JC, Wang G, Holland C, Tynan GR, Austin ME, McKee GR, Shafer MW, Burrell KH, Candy J, DeBoo JC, Prater R, Staebler GM, Waltz RE, Makowski MA. A correlation electron cyclotron emission diagnostic and the importance of multifield fluctuation measurements for testing nonlinear gyrokinetic turbulence simulations. Rev Sci Instrum 2008; 79:103505. [PMID: 19044712 DOI: 10.1063/1.2981186] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A correlation electron cyclotron emission (CECE) diagnostic has been used to measure local, turbulent fluctuations of the electron temperature in the core of DIII-D plasmas. This paper describes the hardware and testing of the CECE diagnostic and highlights the importance of measurements of multifield fluctuation profiles for the testing and validation of nonlinear gyrokinetic codes. The process of testing and validating such codes is critical for extrapolation to next-step fusion devices. For the first time, the radial profiles of electron temperature and density fluctuations are compared to nonlinear gyrokinetic simulations. The CECE diagnostic at DIII-D uses correlation radiometry to measure the rms amplitude and spectrum of the electron temperature fluctuations. Gaussian optics are used to produce a poloidal spot size with w(o) approximately 1.75 cm in the plasma. The intermediate frequency filters and the natural linewidth of the EC emission determine the radial resolution of the CECE diagnostic, which can be less than 1 cm. Wavenumbers resolved by the CECE diagnostic are k(theta) < or = 1.8 cm(-1) and k(r) < or = 4 cm(-1), relevant for studies of long-wavelength turbulence associated with the trapped electron mode and the ion temperature gradient mode. In neutral beam heated L-mode plasmas, core electron temperature fluctuations in the region 0.5 < r/a < 0.9, increase with radius from approximately 0.5% to approximately 2%, similar to density fluctuations that are measured simultaneously with beam emission spectroscopy. After incorporating "synthetic diagnostics" to effectively filter the code output, the simulations reproduce the characteristics of the turbulence and transport at one radial location r/a = 0.5, but not at a second location, r/a = 0.75. These results illustrate that measurements of the profiles of multiple fluctuating fields can provide a significant constraint on the turbulence models employed by the code.
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Affiliation(s)
- A E White
- University of California-Los Angeles, Los Angeles, California 90095, USA
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13
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Holland C, Candy J, Waltz RE, White AE, McKee GR, Shafer MW, Schmitz L, Tynan GR. Validating simulations of core tokamak turbulence: current status and future directions. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1742-6596/125/1/012043] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Candy J, Waltz RE. Anomalous transport scaling in the DIII-D tokamak matched by supercomputer simulation. Phys Rev Lett 2003; 91:045001. [PMID: 12906667 DOI: 10.1103/physrevlett.91.045001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2002] [Indexed: 05/24/2023]
Abstract
Gyrokinetic simulation of tokamak transport has evolved sufficiently to allow direct comparison of numerical results with experimental data. It is to be emphasized that only with the simultaneous inclusion of many distinct and complex effects can this comparison realistically be made. Until now, numerical studies of tokamak microturbulence have been restricted to either (a) flux tubes or (b) electrostatic fluctuations. Using a newly developed global electromagnetic solver, we have been able to recover via direct simulation the Bohm-like scaling observed in DIII-D L-mode discharges. We also match, well within experimental uncertainty, the measured energy diffusivities.
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Affiliation(s)
- J Candy
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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16
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Abstract
Mac25, connective tissue growth factor, the nov-oncogene and cyr61 have been proposed as insulin-like growth factor binding proteins (IGFBPs) although they bind the ligand with very low affinity. Sequence similarity between the candidate proteins and the recognised IGFBPs is restricted to a single cysteine-rich N-terminal domain. The cysteine-rich domain (CRD) can be found in other vertebrate and invertebrate proteins that are associated with the extracellular matrix but otherwise have vastly different functions. Characteristically, the proteins with the CRD have a modular architecture suggesting that exon shuffling has played a significant role in their evolution. Although the proposed candidate proteins may not be IGFBPs, linkage relationships of the latter suggest that two other IGFBPs may indeed exist.
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Affiliation(s)
- C Collet
- Centre for Molecular Biotechnology, School of Life Sciences, Queensland University of Technology, Brisbane, Australia.
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Collet C, Candy J, Sara V. Tyrosine hydroxylase and insulin-like growth factor II but not insulin are adjacent in the teleost species barramundi, Lates calcarifer. Anim Genet 1998; 29:30-2. [PMID: 9682446 DOI: 10.1046/j.1365-2052.1998.00227.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In humans, the genes encoding tyrosine hydroxylase (TH), insulin and insulin-like growth factor II (IGF-II) form an extremely tight linkage group on chromosome 11p15. Characterisation of the homologous genomic region of a teleost, the barramundi Lates calcarifer, revealed tight linkage of the TH and IGF-II genes, and the absence of the gene encoding insulin.
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Affiliation(s)
- C Collet
- Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Brisbane, Australia
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18
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Collet C, Candy J, Richardson N, Sara V. Organization, sequence, and expression of the gene encoding IGFII from barramundi (Teleosteii; Lates calcarifer). Biochem Genet 1997; 35:211-24. [PMID: 9435942 DOI: 10.1023/a:1021840931297] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have characterized the gene encoding IGFII from the teleost fish species barramundi, Lates calcarifer. The barramundi gene spans 5.5 kb of DNA and comprises four exons and three introns. The barramundi and salmon IGFII genes share > 85% sequence similarity across all the exons and also share some regions of high sequence identity within the promoter regions and the introns. The mature barramundi IGFII peptide comprises 70 amino acid residues and shares 84 and 96% similarity with salmonid and seabream IGFII, respectively, with the majority of replacements located in regions cleaved from the mature peptide. IGFII mRNA transcripts were detected in liver, muscle, intestine, gill, heart, and brain from juvenile barramundi. This distribution mirrors that seen in the rainbow trout and seabream and extends the tissue types which synthesize IGFII in fish to include the intestine.
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Affiliation(s)
- C Collet
- Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Brisbane, Australia
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Davidson J, Stefani L, Candy J, Hughes D, Neill D, Edwardson J. Expression of chromosome 21 specific DNA sequences in brain tissue and in neuronal cell lines. Biochem Soc Trans 1991; 19:200S. [PMID: 1889579 DOI: 10.1042/bst019200s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- J Davidson
- School of Biology and Biochemistry, Queen's University of Belfast
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Abstract
The distribution of NMDA receptors in the normal human spinal cord has been investigated using the non-competitive channel blocking agent MK-801. Specific [3H]MK-801 binding was present throughout the spinal grey matter at all segmental levels, the greatest density of binding being found in the substantia gelatinosa. Focal areas of high binding were also found in a distribution corresponding to lower motor neurones in the ventral horns. This study provides anatomical evidence that NMDA receptors are likely to be important in motor as well as sensory spinal synaptic transmission. The anatomical distribution of NMDA receptors in relation to motor neurone somata may have important implications in selective vulnerability to excitotoxic injury.
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Affiliation(s)
- P J Shaw
- Department of Neurology, University of Newcastle upon Tyne, U.K
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Parsons PG, Takahashi H, Candy J, Meyers B, Vickers J, Kelly WR, Smith I, Spradbrow P. Histopathology of melanocytic lesions in goats and establishment of a melanoma cell line: a potential model for human melanoma. Pigment Cell Res 1990; 3:297-305. [PMID: 2101929 DOI: 10.1111/j.1600-0749.1990.tb00301.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Melanocytic cells from white Angora goats were studied in vivo and in vitro. The histopathology of pigmented areas of skin from the most common sites of melanoma (solar-exposed areas of the ear, face, and perineum) resembled that of the epidermal melanocytes in Hutchinson's melanotic freckle in humans. Seven melanoma biopsies from 6 Angora goats showed histopathological features in common with human melanoma. A melanoma cell line, GM-1, was established in culture from a lymph node metastasis obtained from an animal that had a primary tumor excised and later developed extensive metastatic disease. GM-1 cells were mainly diploid, amelanotic, proliferated rapidly, spontaneously formed vacuolated cells, and were tumorigenic in nude mice. The species of origin of the GM-1 line was confirmed by isozyme profiles. GM-1 cultured cells and the original biopsy both expressed S-100 protein and tyrosinase antigen. Using GM-1 cells as the immunogen, a monoclonal antibody (MoAb 1F1) was derived that reacted strongly with a 116 kDa antigen in 50% of the GM-1 cells, but had little activity with goat fibroblasts (GM-F) or with human melanoma cells. GM-F, on the other hand, yielded more intense staining than GM-1 with an intermediate filament antibody (IFA), reacting with a 58 kDa antigen in both cell lines. The sensitivity of GM-1 to anticancer agents was similar to that of human melanoma cells. The pathology of caprine melanoma and its association with sun-exposed sites in relatively young animals suggest that it may be a suitable model for studying induction of melanoma by natural sunlight.
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Affiliation(s)
- P G Parsons
- Queensland Institute of Medical Research, Herston, Brisbane, Australia
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Abstract
A reduction in the levels of somatostatin-like immunoreactivity (SLI) and somatostatin binding sites in the cerebral cortex has been previously reported to occur in Alzheimer's disease (AD) and Parkinson's disease with associated dementia. In the present study, the levels of both SLI and high affinity [3H]somatostatin binding sites have been measured in the frontal (Brodmann area 9) and temporal (Brodmann area 21) cortices in patients with presenile and senile Alzheimer's disease, and in mentally normal and cognitively impaired cases of Parkinson's disease. The results were compared with those obtained from a group of normal patients matched for age and postmortem delay. No significant changes in SLI or somatostatin binding in the frontal and temporal cortex were found between any of the disease groups. These results suggest that involvement of the somatostatinergic system in AD or Parkinson's disease is not a consistent or primary neurochemical feature of these diseases.
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Affiliation(s)
- C Whitford
- MRC Neuroendocrinology Unit, Newcastle General Hospital, Newcastle upon Tyne, U.K
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Court J, Ferrier N, Griffiths H, Lauffart B, Perry R, Candy J, Fairbairn A, Blessed G. Serum creatine kinase-BB levels and cerebral cortical creatine kinase activity in senile dementia of the Alzheimer type. J Neurol Sci 1987; 80:111-5. [PMID: 3612178 DOI: 10.1016/0022-510x(87)90225-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A rise in serum creatine kinase-BB (CK-BB) levels has been reported previously in cases of dementia. In the present study the levels of serum CK-BB have been measured in patients clinically assessed to have senile dementia of the Alzheimer's type (SDAT) and in cognitively intact individuals, matched for age, by a specific two-site monoclonal immunoradiometric assay. No significant difference was found between the 2 groups. Total creatine kinase activity in temporal cortex (Brodmann area 21 and 22) was also found to be similar in brains from SDAT or control cases, obtained at autopsy. These results suggest no major change in the permeability of the blood-brain barrier to this enzyme in SDAT patients.
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Candy J. Mental hospitals and community care. J R Soc Med 1987; 80:257. [PMID: 20894648 PMCID: PMC1290776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023] Open
Affiliation(s)
- J Candy
- St John's Hospital, Aylesbury
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Cross A, Slater P, Candy J, Perry E, Perry R. Glutamate deficits in Alzheimer's disease. Journal of Neurology, Neurosurgery & Psychiatry 1987. [DOI: 10.1136/jnnp.50.3.357] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Rowe IF, Jensson O, Lewis PD, Candy J, Tennent GA, Pepys MB. Immunohistochemical demonstration of amyloid P component in cerebro-vascular amyloidosis. Neuropathol Appl Neurobiol 1984; 10:53-61. [PMID: 6377111 DOI: 10.1111/j.1365-2990.1984.tb00340.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The presence of amyloid P component (AP) in cerebral amyloid deposits was sought using a direct immunoperoxidase technique. AP was detected in the amyloid deposits in the vessel walls but was absent from the intracerebral plaques in tissue from patients with senile cerebral amyloidosis. AP was also present in the amyloid deposits in the vessel walls of patients with the Icelandic form of hereditary cerebral haemorrhage associated with amyloidosis.
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Cawley R, Candy J, Malan D, Marks I. Dynamic Psychotherapy: Can it be Evaluated. Proc R Soc Med 1973; 66:943-945. [PMID: 20919148 PMCID: PMC1645456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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Abstract
SynopsisA double-blind trial of phenelzine versus placebo in psychiatric outpatients with long-standing phobic anxiety is described. Forty patients with agoraphobia or social phobias entered the trial and 32 of these completed treatment with either phenelzine or placebo (with appropriate dietary restrictions) in flexible dosage for two months. Fourteen pairs of patients were prospectively matched, and analysis of the score differences between these pairs showed a significant improvement for patients on phenelzine compared with placebo on overall assessment (P<0·01) and secondary phobias (P<0·05). These differences were not shown at assessment after one month's treatment, but became marked after two months. The improvement on phenelzine, which was maintained at follow-up, was not related to initial depressive symptoms in the patients. It is suggested that phenelzine is an effective agent in the treatment of phobic anxiety but that treatment needs to be continued for at least two months before full benefit is achieved.
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Abstract
SynopsisA feasibility study for a controlled trial of a certain type of formal psychotherapy is described. Patients referred by consultant psychiatrists in the Inner London Area were carefully selected and fully assessed before random allocation to one of three treatment procedures. The results indicate that the trial as initially envisaged is not feasible. The reasons for this conclusion are discussed.
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Abstract
This paper describes two cases of gastric leiomyoblastoma (bizarre smooth muscle tumour), one of them having evidence of metastases. Both patients remain well after seven years and three and a half years respectively. The literature is reviewed, and the clinical features, diagnosis, and treatment are discussed. The histological appearances are described in detail and an attempt is made to assess the criteria for the diagnosis of malignancy.
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Candy J. Remarks on the "Case of Fatal Thermal Fever(?) by Surgeon-Major G. C. Gribbon, M. B., A. M. D.". Ind Med Gaz 1879; 14:84-85. [PMID: 28998700 PMCID: PMC5146519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- J. Candy
- Surgeon-Major A.M.D. Ramandroog Convalescent Depôt Near Bellary
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Candy J. Case of Abscess of the Liver: Of Hydatid Origin. Ind Med Gaz 1871; 6:184. [PMID: 28995635 PMCID: PMC5160247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Candy J. Case of Acute Hydrocephalus: Recovery. West J Med 1863. [DOI: 10.1136/bmj.1.125.537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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