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Sample records for alcator c-mod research

  1. Overview of Alcator C-Mod Research

    Science.gov (United States)

    White, Anne

    2015-11-01

    Research on C-Mod supports next-step-devices: RF heating, current and flow drive, divertor/PMI physics, non-ELMing regimes with enhanced confinement, and disruption mitigation/runaway dynamics. Disruption mitigation experiments in MHD-unstable plasmas show MGI works equally well with and without locked modes. The L-I-mode threshold is found to be independent of magnetic field, opening an expanded operating range at high field. The toroidal and radial structure of power deposition of RF waves into the edge plasma has been systematically quantified, through the use of a unique set of fast time resolution edge diagnostics. Progress in understanding multi-channel core transport has been significant. Full-physics, ITG/TEM/ETG gyrokinetic simulations show that nonlinear cross-scale coupling enhances both ion and electron heat flux to match experiments, explaining the origin of electron heat flux and stiffness. Dynamic, passive measurements of the core rotation velocity profiles with X-ray imaging crystal spectroscopy show the direction of intrinsic rotation reversals depends on central safety factor, not on the magnetic shear. Design studies for ADX and SPARC are establishing the engineering, economics and physics for a fusion energy development path leveraging new superconducting magnet technologies. This work is supported by the US DOE under DE- FC02-99ER54512-CMOD.

  2. Overview of the Alcator C-Mod Research Program

    Science.gov (United States)

    Marmar, E.; Bader, A.; Bakhtiari, M.; Barnard, H.; Beck, W.; Bespamyatnov, I.; Binus, A.; Bonoli, P.; Bose, B.; Bitter, M.; Cziegler, I.; Dekow, G.; Dominguez, A.; Duval, B.; Edlund, E.; Ernst, D.; Ferrara, M.; Fiore, C.; Fredian, T.; Graf, A.; Granetz, R.; Greenwald, M.; Grulke, O.; Gwinn, D.; Harrison, S.; Harvey, R.; Hender, T. C.; Hosea, J.; Hill, K.; Howard, N.; Howell, D. F.; Hubbard, A.; Hughes, J. W.; Hutchinson, I.; Ince-Cushman, A.; Irby, J.; Izzo, V.; Kanojia, A.; Kessel, C.; Ko, J. S.; Koert, P.; La Bombard, B.; Lau, C.; Lin, L.; Lin, Y.; Lipschultz, B.; Liptac, J.; Ma, Y.; Marr, K.; May, M.; McDermott, R.; Meneghini, O.; Mikkelsen, D.; Ochoukov, R.; Parker, R.; Phillips, C. K.; Phillips, P.; Podpaly, Y.; Porkolab, M.; Reinke, M.; Rice, J.; Rowan, W.; Scott, S.; Schmidt, A.; Sears, J.; Shiraiwa, S.; Sips, A.; Smick, N.; Snipes, J.; Stillerman, J.; Takase, Y.; Terry, D.; Terry, J.; Tsujii, N.; Valeo, E.; Vieira, R.; Wallace, G.; Whyte, D.; Wilson, J. R.; Wolfe, S.; Wright, G.; Wright, J.; Wukitch, S.; Wurden, G.; Xu, P.; Zhurovich, K.; Zaks, J.; Zweben, S.

    2009-10-01

    This paper summarizes highlights of research results from the Alcator C-Mod tokamak covering the period 2006-2008. Active flow drive, using mode converted ion cyclotron waves, has been observed for the first time in a tokamak plasma, using a mix of D and 3He ion species; toroidal and poloidal flows are driven near the location of the mode conversion layer. ICRF induced edge sheaths are implicated in both the erosion of thin boron coatings and the generation of metallic impurities. Lower hybrid range of frequencies (LHRF) microwaves have been used for efficient current drive, current profile modification and toroidal flow drive. In addition, LHRF has been used to modify the H-mode pedestal, increasing temperature, decreasing density and lowering the pedestal collisionality. Studies of hydrogen isotope retention in solid metallic plasma facing components reveal significantly higher retention than expected from ex situ laboratory studies; a model to explain the results, based on plasma/neutral induced lattice damage, has been developed and tested. During gas-puff mitigation of disruptions, induced MHD instabilities cause the magnetic field to become stochastic, resulting in reduction of halo currents, spreading of plasma power loading and loss of runaway electrons before they cause damage. Detailed pedestal rotation profile measurements have been used to infer Er profiles, and correlation with global H-mode confinement. An improved L-mode regime, obtained at q95 <= 3 with ion drift away from the active X-point, shows very good energy confinement with a strong temperature pedestal, a weak density pedestal, and no evidence of particle or impurity accumulation, without the need for ELMs or any additional edge density regulation mechanism.

  3. Overview of the Alcator C-MOD research programme

    Science.gov (United States)

    Scott, S.; Bader, A.; Bakhtiari, M.; Basse, N.; Beck, W.; Biewer, T.; Bernabei, S.; Bonoli, P.; Bose, B.; Bravenec, R.; Bespamyatnov, I.; Childs, R.; Cziegler, I.; Doerner, R.; Edlund, E.; Ernst, D.; Fasoli, A.; Ferrara, M.; Fiore, C.; Fredian, T.; Graf, A.; Graves, T.; Granetz, R.; Greenough, N.; Greenwald, M.; Grimes, M.; Grulke, O.; Gwinn, D.; Harvey, R.; Harrison, S.; Hender, T. C.; Hosea, J.; Howell, D. F.; Hubbard, A. E.; Hughes, J. W.; Hutchinson, I.; Ince-Cushman, A.; Irby, J.; Jernigan, T.; Johnson, D.; Ko, J.; Koert, P.; La Bombard, B.; Kanojia, A.; Lin, L.; Lin, Y.; Lipschultz, B.; Liptac, J.; Lynn, A.; MacGibbon, P.; Marmar, E.; Marr, K.; May, M.; Mikkelsen, D. R.; McDermott, R.; Parisot, A.; Parker, R.; Phillips, C. K.; Phillips, P.; Porkolab, M.; Reinke, M.; Rice, J.; Rowan, W.; Sampsell, M.; Schilling, G.; Schmidt, A.; Smick, N.; Smirnov, A.; Snipes, J.; Stotler, D.; Stillerman, J.; Tang, V.; Terry, D.; Terry, J.; Ulrickson, M.; Vieira, R.; Wallace, G.; Whyte, D.; Wilson, J. R.; Wright, G.; Wright, J.; Wolfe, S.; Wukitch, S.; Wurden, G.; Yuh, H.; Zhurovich, K.; Zaks, J.; Zweben, S.

    2007-10-01

    Alcator C-MOD has compared plasma performance with plasma-facing components (PFCs) coated with boron to all-metal PFCs to assess projections of energy confinement from current experiments to next-generation burning tokamak plasmas. Low-Z coatings reduce metallic impurity influx and diminish radiative losses leading to higher H-mode pedestal pressure that improves global energy confinement through profile stiffness. RF sheath rectification along flux tubes that intersect the RF antenna is found to be a major cause of localized boron erosion and impurity generation. Initial lower hybrid current drive (LHCD) experiments (PLH < 900 kW) in preparation for future advanced-tokamak studies have demonstrated fully non-inductive current drive at Ip ~ 1.0 MA with good efficiency, Idrive = 0.4 PLH/neoR (MA, MW, 1020 m-3,m). The potential to mitigate disruptions in ITER through massive gas-jet impurity puffing has been extended to significantly higher plasma pressures and shorter disruption times. The fraction of total plasma energy radiated increases with the Z of the impurity gas, reaching 90% for krypton. A positive major-radius scaling of the error field threshold for locked modes (Bth/B ~ R0.68±0.19) is inferred from its measured variation with BT that implies a favourable threshold value for ITER. A phase contrast imaging diagnostic has been used to study the structure of Alfvén cascades and turbulent density fluctuations in plasmas with an internal transport barrier. Understanding the mechanisms responsible for regulating the H-mode pedestal height is also crucial for projecting performance in ITER. Modelling of H-mode edge fuelling indicates high self-screening to neutrals in the pedestal and scrape-off layer (SOL), and reproduces experimental density pedestal response to changes in neutral source, including a weak variation of pedestal height and constant width. Pressure gradients in the near SOL of Ohmic L-mode plasmas are observed to scale consistently as I_p^2

  4. 20 years of research on the Alcator C-Mod tokamak

    OpenAIRE

    Greenwald, Martin; Bader, A; Baek, S.; M. Bakhtiari; Barnard, H.; Beck, W.; Bergerson, W; Bespamyatnov, I; Bonoli, P.; Brower, D; Brunner, D.; Burke, W.; Candy, J.; Churchill, M; Cziegler, I.

    2014-01-01

    The object of this review is to summarize the achievements of research on the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994) and Marmar, Fusion Sci. Technol. 51, 261 (2007)] and to place that research in the context of the quest for practical fusion energy. C-Mod is a compact, high-field tokamak, whose unique design and operating parameters have produced a wealth of new and important results since it began operation in 1993, contributing data that extends tests of crit...

  5. Alcator C-MOD proposal addendum

    International Nuclear Information System (INIS)

    Since the design concept and overall purpose of the Alcator C-MOD device are similar to that proposed in October 1985, we have chosen in this document only to highlight areas where changes or additions have been made. Chapters in the Addendum correspond to those in the Proposal, except Chapter 9 which describes a number of toroidal improvement concepts which are being considered for inclusion in the Alcator C-MOD experimental program. A description of the redesign and a discussion of the objectives of the experimental program are given

  6. Alcator C-MOD final safety analysis

    International Nuclear Information System (INIS)

    This document is designed to address the safety issues involved with the Alcator C-Mod project. This report will begin with a brief description of the experimental objectives which will be followed by information concerning the site. The Alcator C-Mod experiment is a pulsed fusion experiment in which a plasma formed from small amounts of hydrogen or deuterium gas is confined in a magnetic field for short periods (∼1 s). No radioactive fuels or fissile materials are used in the device, so that no criticality hazard exists and no credible nuclear accident can occur. During deuterium operation, the production of a small number of neutrons from a short pulse could result in a small amount of short- and intermediate-lived radioactive isotopes being produced inside the experimental cell. This report will demonstrate that this does not pose an additional hazard to the general population. The health and safety hazards resulting from Alcator C-Mod occur to the workers on the experiment, each of which is described in its own chapter with the steps taken to minimize the risk to employees. These hazards include fire, chemicals and cryogenics, air quality, electrical, electromagnetic radiation, ionizing radiation, and mechanical and natural phenomena. None of these hazards is unique to the facility, and methods of protection from them are well defined and are discussed in the chapter which describes each hazard. The quality assurance program, critical to ensuring the safety aspects of the program, will also be described

  7. Axisymmetric Control in Alcator C-Mod

    Science.gov (United States)

    Tinios, Gerasimos

    1995-01-01

    This thesis investigates the degree to which linear axisymmetric modeling of the response of a tokamak plasma can reproduce observed experimental behavior. The emphasis is on the vertical instability. The motivation for this work lies in the fact that, once dependable models have been developed, modern control theory methods can be used to design feedback laws for more effective and efficient tokamak control. The models are tested against experimental data from the Alcator C-Mod tokamak. A linear model for each subsystem of the closed-loop system constituting an Alcator C-Mod discharge under feedback control has been constructed. A non-rigid, approximately flux-conserving, perturbed equilibrium plasma response model is used in the comparison to experiment. A detailed toroidally symmetric model of the vacuum vessel and the supporting superstructure is used. Modeling of the power supplies feeding the active coils has been included. Experiments have been conducted with vertically unstable plasmas where the feedback was turned off and the plasma response was observed in an open -loop configuration. The closed-loop behavior has been examined by injecting step perturbations into the desired vertical position of the plasma. The agreement between theory and experiment in the open-loop configuration was very satisfactory, proving that the perturbed equilibrium plasma response model and a toroidally symmetric electromagnetic model of the vacuum vessel and the structure can be trusted for the purpose of calculations for control law design. When the power supplies and the feedback computer hardware are added to the system, however, as they are in the closed-loop configuration, they introduce nonlinearities that make it difficult to explain observed behavior with linear theory. Nonlinear simulation of the time evolution of the closed-loop experiments was able to account for the discrepancies between linear theory and experiment. (Copies available exclusively from MIT Libraries

  8. First results from Alcator-C-MOD

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, I.H.; Boivin, R.; Bombarda, F.; Bonoli, P.; Fairfax, S.; Fiore, C.; Goetz, J.; Golovato, S.; Granetz, R.; Greenwald, M.; Horne, S.; Hubbard, A.; Irby, J.; LaBombard, B.; Lipschultz, B.; Marmar, E.; McCracken, G.; Porkolab, M.; Rice, J.; Snipes, J.; Takase, Y.; Terry, J.; Wolfe, S.; Christensen, C.; Garnier, D.; Graf, M.; Hsu, T.; Luke, T.; May, M.; Niemczewski, A.; Tinios, G.; Schachter, J.; Urbahn, J. (Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States))

    1994-05-01

    Early operation of the Alcator-C-MOD tokamak [I.H. Hutchinson, [ital Proceedings] [ital of] [ital IEEE] 13[ital th] [ital Symposium] [ital on] [ital Fusion] [ital Engineering], Knoxville, TN, edited by M. Lubell, M. Nestor, and S. Vaughan (Institute of Electrical and Electronic Engineers, New York, 1990), Vol. 1, p. 13] is surveyed. Reliable operation, with plasma current up to 1 MA, has been obtained, despite the massive conducting superstructure and the associated error fields. However, vertical disruptions are not slowed by the long vessel time constant. With pellet fueling, peak densities up to 9[times]10[sup 20] m[sup [minus]3] have been attained and snakes'' are often seen. Initial characterization of divertor and scrape-off layer is presented and indicates approximately Bohm diffusion. The edge plasma shows a wealth of marfe-like phenomena, including a transition to detachment from the divertor plates with accompanying radiative divertor regions. Energy confinement generally appears to exceed the expectations of neo-Alcator scaling. A transition to Ohmic H mode has been observed. Ion cyclotron heating experiments have demonstrated good power coupling, in agreement with theory.

  9. Transport experiments in Alcator-C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Greenwald, M.; Boivin, R.L.; Bonoli, P.; Christensen, C.; Fiore, C.; Garnier, D.; Goetz, J.; Golovato, S.; Graf, M.; Granetz, R.; Horne, S.; Hsu, T.; Hubbard, A.; Hutchinson, I.; Irby, J.; Kurz, C.; LaBombard, B.; Lipschultz, B.; Luke, T.; Marmar, E.; McCracken, G.; Niemczewski, A.; O`Shea, P.; Porkolab, M.; Rice, J.; Reardon, J.; Schachter, J.; Snipes, J.; Stek, P.; Takase, Y.; Terry, J.; Umansky, M.; Watterson, R.; Wolfe, S. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bombarda, F. [ENEA-Frascati, Frascati (Italy); May, M. [Johns Hopkins University, Baltimore, Maryland 21218 (United States); Welch, B. [University of Maryland, College Park, Maryland 20742 (United States)

    1995-06-01

    A series of transport experiments has been carried out in Alcator-C-Mod. [Phys Plasmas {bold 1}, 1511 (1994)]. Data from both Ohmic and ICRF (ion cyclotron range of frequencies) heated plasmas can be fitted with an L-mode (low mode) scaling law. The Ohmic {tau}{sub {ital E}}`s show no scaling with density in any regime and can reach values of 2--3 times neo-Alcator. Impurity confinement has been studied with the laser blow-off technique with {tau}{sub {ital I}} showing nearly linear scaling with plasma current. Ohmic and ICRF H modes are obtained over a wide range of discharge parameters, extending the range in the international database for {ital nB}, by almost a factor of 10. The power threshold for ELM-free (edge localized mode) discharges is in rough agreement with the scaling {ital P}/{ital S}=0.044{ital nB}. Energy diffusivities of Ohmic and ICRF heated plasmas have been measured from local analysis of plasma profiles and power fluxes. The same analysis produces a value for plasma resistivity which lies between the Spitzer and neoclassical calculations. Analysis of plasma transients have yielded values for particle diffusivity and convection velocity.

  10. The physics and engineering of Alcator C-Mod

    International Nuclear Information System (INIS)

    Alcator C-Mod is a new tokamak under construction at M.I.T. that promises to play an important and flexible role in the international fusion research effort. The physics and engineering features of the tokamak are described, giving an overview of the machine and plasma configurations. On the basis of empirical scaling laws, we predict the plasma confinement performance to be near DT equivalent breakeven. The planned experimental program is addressed to many of the vital physics questions still uncertain in high-performance tokamak plasma behaviour as well as to the investigation of innovative approaches to tokamak improvement. 17 refs., 17 figs., 3 tabs

  11. Disruptions and halo currents in Alcator C-Mod

    Science.gov (United States)

    Granetz, R. S.; Hutchinson, I. H.; Sorci, J.; Irby, J. H.; La Bombard, B.; Gwinn, D.

    1996-05-01

    Disruptions in Alcator C-Mod can generate large eddy currents in the highly conducting vacuum vessel and internal structures, including a significant poloidal component due to halo currents. In order to understand better the stresses arising from the resulting J*B forces, Alcator C-Mod has been fitted with a comprehensive set of sensors to measure the spatial distribution and temporal behaviour of the halo currents. It is found that they are toroidally asymmetric, with a typical peaking factor of 2. The asymmetric pattern usually rotates toroidally at a few kilohertz, thus ruling out first wall non-uniformities as the cause of the asymmetry. Analysis of the information compiled in the C-Mod disruption database indicates that the maximum halo current during a disruption scales roughly as either Ip2/Bphi or Ip/q95, but that there is a large amount of variation that is not yet understood

  12. Divertor bypass in the Alcator C-Mod tokamak

    Science.gov (United States)

    Pitcher, C. S.; LaBombard, B.; Danforth, R.; Pina, W.; Silveira, M.; Parkin, B.

    2001-01-01

    The Alcator C-Mod divertor bypass has for the first time allowed in situ variations to the mechanical baffle design in a tokamak. The design utilizes small coils which interact with the ambient magnetic field inside the vessel to provide the torque required to control small flaps of a Venetian blind geometry. Plasma physics experiments with the bypass have revealed the importance of the divertor baffling to maintain high divertor gas pressures. These experiments have also indicated that the divertor baffling has only a limited effect on the main chamber pressure in C-Mod.

  13. ICRF heating antennas for Alcator C-Mod

    International Nuclear Information System (INIS)

    Initial ICRF coupling studies were performed successfully on the Alcator C-Mod tokamak with all-metallic first wall, using a radially movable single current strap (monopole) antenna. The plasma loading is 10-30 times the vacuum loading, which is sufficient to inject 2 MW of RF power through one two-strap (dipole) antenna. The observed loading is consistent with predictions of full-wave calculations. Up to 1 MW of RF power (antenna power density of > or approx. 10 MW/m2) has been injected into the C-Mod plasma with no increase in the fractional radiated power Prad/Pin. Definite signs of both ion and electron heating were observed at power levels of 0.4 MW and higher (PRF/POH > or approx. 0.3) in the D(H) minority heating regime. High power heating experiments with 4 MW of source power and two dipole antennas will begin in early 1994. (author)

  14. Planning for US ion cyclotron heating research relevant to the Compact Ignition Tokamak and Alcator C-Mod

    International Nuclear Information System (INIS)

    Ion cyclotron heating (ICH) has been chosen as the primary method for providing auxiliary heating power to the plasma in the Compact Ignition Tokamak (CIT). Sustained progress in ion cyclotron range of frequencies (ICRF) heating experiments, together with supporting technology development, continues to justify selection of this technique as the preferred one for heating CIT to ignition. However, the CIT requirements are sufficiently different from existing achievements that continued experimentation and development are needed to meet the goals of the CIT experiment with a high degree of reliability. The purpose of this report is fourfold: (1) to review briefly the physics and technology research and development (R and D) needs for ICH on CIT, (2) to review the status of and planned programs for ICH on US and international machines, (3) to propose a unified ''mainline'' R and D program specifically geared to testing components for CIT, and (4) to assess the needs for experiments including C-Mod, the Tokamak Fusion Test Reactor (TFTR), and DIII-D to provide earlier information and improved probability of success for CIT ICH. 4 refs., 4 figs., 5 tabs

  15. Modeling of Alcator C-Mod Divertor Baffling Experiments

    Energy Technology Data Exchange (ETDEWEB)

    D. P. Stotler; C. S. Pitcher; C. J. Boswell; T. K. Chung; B. LaBombard; B. Lipschultz; J. L. Terry; R. J. Kanzleiter

    2000-11-29

    A specific Alcator C-Mod discharge from the series of divertor baffling experiments is simulated with the DEGAS 2 Monte Carlo neutral transport code. A simple two-point plasma model is used to describe the plasma variation between Langmuir probe locations. A range of conductances for the bypass between the divertor plenum and the main chamber are considered. The experimentally observed insensitivity of the neutral current flowing through the bypass and of the D alpha emissions to the magnitude of the conductance is reproduced. The current of atoms in this regime is being limited by atomic physics processes and not the bypass conductance. The simulated trends in the divertor pressure, bypass current, and D alpha emission agree only qualitatively with the experimental measurements, however. Possible explanations for the quantitative differences are discussed.

  16. Edge Minority Heating Experiment in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    S.J. Zweben; J.L. Terry; P. Bonoli; R. Budny; C.S. Chang; C. Fiore; G. Schilling; S. Wukitch; J. Hughes; Y. Lin; R. Perkins; M. Porkolab; the Alcator C-Mod Team

    2005-03-25

    An attempt was made to control global plasma confinement in the Alcator C-Mod tokamak by applying ion cyclotron resonance heating (ICRH) power to the plasma edge in order to deliberately create a minority ion tail loss. In theory, an edge fast ion loss could modify the edge electric field and so stabilize the edge turbulence, which might then reduce the H-mode power threshold or improve the H-mode barrier. However, the experimental result was that edge minority heating resulted in no improvement in the edge plasma parameters or global stored energy, at least at power levels of radio-frequency power is less than or equal to 5.5 MW. A preliminary analysis of these results is presented and some ideas for improvement are discussed.

  17. Neutral particle dynamics in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Niemczewski, A.P.

    1995-08-01

    This thesis presents an experimental study of neutral particle dynamics in the Alcator C-Mod tokamak. The primary diagnostic used is a set of six neutral pressure gauges, including special-purpose gauges built for in situ tokamak operation. While a low main chamber neutral pressure coincides with high plasma confinement regimes, high divertor pressure is required for heat and particle flux dispersion in future devices such as ITER. Thus we examine conditions that optimize divertor compression, defined here as a divertor-to-midplane pressure ratio. We find both pressures depend primarily on the edge plasma regimes defined by the scrape-off-layer heat transport. While the maximum divertor pressure is achieved at high core plasma densities corresponding to the detached divertor state, the maximum compression is achieved in the high-recycling regime. Variations in the divertor geometry have a weaker effect on the neutral pressures. For otherwise similar plasmas the divertor pressure and compression are maximum when the strike point is at the bottom of the vertical target plate. We introduce a simple flux balance model, which allows us to explain the divertor neutral pressure across a wide range of plasma densities. In particular, high pressure sustained in the detached divertor (despite a considerable drop in the recycling source) can be explained by scattering of neutrals off the cold plasma plugging the divertor throat. Because neutrals are confined in the divertor through scattering and ionization processes (provided the mean-free-paths are much shorter than a typical escape distance) tight mechanical baffling is unnecessary. The analysis suggests that two simple structural modifications may increase the divertor compression in Alcator C-Mod by a factor of about 5. Widening the divertor throat would increase the divertor recycling source, while closing leaks in the divertor structure would eliminate a significant neutral loss mechanism. 146 refs., 82 figs., 14 tabs.

  18. Correlation ECE diagnostic in Alcator C-Mod

    International Nuclear Information System (INIS)

    Correlation ECE (CECE) is a diagnostic technique that allows measurement of small amplitude electron temperature, Te, fluctuations through standard cross-correlation analysis methods. In Alcator C-Mod, a new CECE diagnostic has been installed[Sung RSI 2012], and interesting phenomena have been observed in various plasma conditions. We find that local Te fluctuations near the edge (ρ ~ 0:8) decrease across the linearto- saturated ohmic confinement transition, with fluctuations decreasing with increasing plasma density [Sung NF 2013], which occurs simultaneously with rotation reversals [Rice NF 2011]. Te fluctuations are also reduced across core rotation reversals with an increase of plasma density in RF heated L-mode plasmas, which implies that the same physics related to the reduction of Te fluctuations may be applied to both ohmic and RF heated L-mode plasmas. In I-mode plasmas, we observe the reduction of core Te fluctuations, which indicates changes of turbulence occur not only in the pedestal region but also in the core across the L/I transition [White NF 2014]. The present CECE diagnostic system in C-Mod and these experimental results are described in this paper

  19. Implementation of LHCD Experiments on Alcator C-Mod

    Science.gov (United States)

    Parker, R.; Basse, N.; Beck, W.; Bernabei, S.; Childs, R.; Ellis, R.; Fredd, E.; Greenough, N.; Grimes, M.; Gwinn, D.; Hosea, J.; Irby, J.; Koert, P.; Kung, C. C.; Labombard, B.; Liptac, J.; Loesser, G. D.; Marmar, E.; Schilling, G.; Terry, D.; Terry, J.; Vieira, R.; Wallace, G.; Wilson, J. R.; Zaks, J.

    2005-09-01

    An antenna-transmitter system for driving current in the LHRF has been installed in Alcator C-Mod. The antenna is a grill consisting of 4 poloidal rows of waveguides, each with 24 guides in the toroidal direction. Power is supplied by 12 klystrons capable of 250 kW operation at a frequency of 4.6 GHz. Thus the total source power is 3 MW, with about 1.5 MW available to be coupled to the plasma. Power supply and heat throughput limits in C-Mod limit the pulse length to 5 s, which however represents several current redistribution times. With 90° phasing, the n∥ spectrum is sharply peaked at 2.3 and the range 1.5 < n∥ < 3.5 can be accessed dynamically by varying the phase of the klystrons. The system is in the commissioning phase with klystron power limited to ˜20 kW and pulse length to 10 ms. Early results from plasma operation are discussed.

  20. Non-axisymmetric Field Effects on Alcator C-Mod

    Science.gov (United States)

    Wolfe, S.; Hutchinson, I.; Granetz, R.; Rice, J.; Hubbard, A.; Irby, J.; Vieira, R.; Cochran, W.; Gwinn, D.; Rosati, J.; Lynn, A.

    2003-10-01

    A set of coils capable of producing non-axisymmetric, predominantly n=1, fields with different toroidal phase and a range of poloidal mode (m) spectra has been installed on Alcator C-Mod. This coilset has been used to suppress locked modes during low density or high current operation and also to induce locked modes in normally stable configurations in order to study error field effects. Locked modes are observed to result in braking of core toroidal rotation, modification of sawtooth activity, and significant reduction in energy and particle confinement. The inferred value of the threshold perturbation for producing a locked mode is of order B_21/B_T ˜ 10-4, where B_21 is the helically resonant m/n=2/1 field evaluated at the q=2 surface. This value is comparable to extrapolations based on experiments on JET and DIII-D, but is inconsistent with stronger BT and size scaling inferred from Compass-D results(R. J. Buttery, et al., 17th Fusion Energy Conference, Oct. 1998, Yokohama (IAEA-CN-69) EX8/5). The C-Mod result therefore has favorable implications for the locked mode threshold in ITER.

  1. Correlation ECE diagnostic in Alcator C-Mod

    Directory of Open Access Journals (Sweden)

    Sung C.

    2015-01-01

    electron temperature, Te, fluctuations through standard cross-correlation analysis methods. In Alcator C-Mod, a new CECE diagnostic has been installed[Sung RSI 2012], and interesting phenomena have been observed in various plasma conditions. We find that local Te fluctuations near the edge (ρ ~ 0:8 decrease across the linearto- saturated ohmic confinement transition, with fluctuations decreasing with increasing plasma density[Sung NF 2013], which occurs simultaneously with rotation reversals[Rice NF 2011]. Te fluctuations are also reduced across core rotation reversals with an increase of plasma density in RF heated L-mode plasmas, which implies that the same physics related to the reduction of Te fluctuations may be applied to both ohmic and RF heated L-mode plasmas. In I-mode plasmas, we observe the reduction of core Te fluctuations, which indicates changes of turbulence occur not only in the pedestal region but also in the core across the L/I transition[White NF 2014]. The present CECE diagnostic system in C-Mod and these experimental results are described in this paper.

  2. Alcator C-Mod: A high-field divertor tokamak

    Science.gov (United States)

    Lipschultz, B.; Becker, H.; Bonoli, P.; Coleman, J.; Fiore, C.; Golovato, S.; Granetz, R.; Greenwald, M.; Gwinn, D.; Humphries, D.; Hutchinson, I.; Irby, J.; Marmar, E.; Montgomery, D. B.; Najmabadi, F.; Parker, R.; Porkolab, M.; Rice, J.; Sevillano, E.; Takase, Y.; Terry, J.; Watterson, R.; Wolfe, S.

    1989-04-01

    The Alcator C-Mod tokamak is a new device presently under construction at Massachusetts Institute of Technology (M.I.T.) which is scheduled to begin operation in mid-1990. The projected operating parameters are as follows: Toroidal field of 9 T; Ip ≤ 3 MA, R = 66.5 cm, a = 21 cm, κ ≤ 2.0, δ ≤ 0.5, ne ≤ 10 21m-3, PICRF ≤ 6 MW. The divertor configuration includes mechanical baffling as opposed to an 'open' geometry. Under strictly ohmic heating conditions, central Ti and Te are predicted to be in the range 2.5-3.5 keV over the density range (4-8) × 10 20m-3. With the addition of 6 MW of ICRF heating, Ti should vary from 4-8 keV over the same density range (assuming either Kaye-Goldston or Neo-Alcator scalings for electron confinement). Based on edge plasma characterizations from Alcator-C and divertor tokamaks, the scrape-off layer (SOL) properties are predicted to be: λn ≈ 10mm, density at the divertor plate < 2 × 10 21m-3, H 0 ionization mean free path between 1 and 10 mm. Maximum heat loads on various internal components are predicted to be in the range 5-10 MW/m 2. The flexibility of the poloidal field system in forming a number of flux surface geometries will provide further comparisons of the relative impurity control capabilities of double-null, single-null and limiter plasmas.

  3. Edge Turbulence Imaging in the Alcator C-Mod Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    S.J. Zweben; D.P. Stotler; J.L. Terry; B. LaBombard; M. Greenwald; M. Muterspaugh; C.S. Pitcher; the Alcator C-Mod Group; K. Hallatschek; R.J. Maqueda; B. Rogers; J.L. Lowrance; V.J. Mastrocola; G.F. Renda

    2001-11-26

    The 2-D radial vs. poloidal structure of edge turbulence in the Alcator C-Mod tokamak [I.H. Hutchinson, R. Boivin, P.T. Bonoli et al., Nuclear Fusion 41(2001) 1391] was measured using fast cameras and compared with 3-D numerical simulations of edge plasma turbulence. The main diagnostic is Gas Puff Imaging (GPI), in which the visible D(subscript alpha) emission from a localized D(subscript 2) gas puff is viewed along a local magnetic field line. The observed D(subscript alpha) fluctuations have a typical radial and poloidal scale of approximately 1 cm, and often have strong local maxima (''blobs'') in the scrape-off layer. The motion of this 2-D structure motion has also been measured using an ultra-fast framing camera with 12 frames taken at 250,000 frames/sec. Numerical simulations produce turbulent structures with roughly similar spatial and temporal scales and transport levels as that observed in the experiment; however, some differences are also noted, perhaps requiring diagnostic improvement and/or additional physics in the numerical model.

  4. High confinement dissipative divertor operation on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Goetz, J.A.; LaBombard, B.; Lipschultz, B.; Pitcher, C.S.; Terry, J.L.; Boswell, C.; Gangadhara, S.; Pappas, D.; Weaver, J.; Welch, B.; Boivin, R.L.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hubbard, A.; Hutchinson, I.; Irby, J.; Marmar, E.; Mossessian, D.; Porkolab, M.; Rice, J.; Rowan, W.L.; Schilling, G.; Snipes, J.; Takase, Y.; Wolfe, S.; Wukitch, S. [Plasma Science Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1999-05-01

    Alcator C-Mod [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)] has operated a High-confinement-mode (H-mode) plasma together with a dissipative divertor and low core Z{sub eff}. The initially attached plasma is characterized by steady-state enhancement factor, H{sub ITER89P} [P. N. Yushmanov {ital et al.}, Nucl. Fusion {bold 30}, 1999 (1990)], of 1.9, central Z{sub eff} of 1.1, and a radiative fraction of {approximately}50{percent}. Feedback control of a nitrogen gas puff is used to increase radiative losses in both the core/edge and divertor plasmas in almost equal amounts. Simultaneously, the core plasma maintains H{sub ITER89P} of 1.6 and Z{sub eff} of 1.4 in this nearly 100{percent} radiative state. The power and particle flux to the divertor plates have been reduced to very low levels while the core plasma is relatively unchanged by the dissipative nature of the divertor. {copyright} {ital 1999 American Institute of Physics.}

  5. Alcator C-Mod ICRF antenna and matching circuit

    International Nuclear Information System (INIS)

    Alcator C-Mod will be a compact, high field, high density, divertor tokamak. Two FMIT transmitters will supply 4 MW of power in 1 sec pulses at 80 MHz for ICRF heating. Fast wave minority heating experiments are planned in D(3He) at 8 T and D(H) at 5.5 T. The first antenna will have a single current strap inside a box structure, which will be movable radially. The antenna will be inserted through a side port, making the rf power density on the antenna surface ∼2 kW/cm2 at 2 MW. The antenna will be center-tapped for mechanical strength and have a double layer Faraday screen tilted along the field lines. The antenna geometry was chosen to maximize power coupling assuming voltage-limited operation. A wide antenna with slotted box sides appears the best design, and 10 Ω of loading is required to couple 2 MW of power at a voltage limit of 40 kV. Matching is achieved by choice of the drive point to a resonant circuit formed by the antenna and a loop of transmission line outside of the vacuum and by tuning elements in the transmission line to the transmitter. 6 refs., 4 figs

  6. Edge Turbulence Imaging in the Alcator C-Mod Tokamak

    International Nuclear Information System (INIS)

    The 2-D radial vs. poloidal structure of edge turbulence in the Alcator C-Mod tokamak [I.H. Hutchinson, R. Boivin, P.T. Bonoli et al., Nuclear Fusion 41(2001) 1391] was measured using fast cameras and compared with 3-D numerical simulations of edge plasma turbulence. The main diagnostic is Gas Puff Imaging (GPI), in which the visible D(subscript alpha) emission from a localized D(subscript 2) gas puff is viewed along a local magnetic field line. The observed D(subscript alpha) fluctuations have a typical radial and poloidal scale of approximately 1 cm, and often have strong local maxima (''blobs'') in the scrape-off layer. The motion of this 2-D structure motion has also been measured using an ultra-fast framing camera with 12 frames taken at 250,000 frames/sec. Numerical simulations produce turbulent structures with roughly similar spatial and temporal scales and transport levels as that observed in the experiment; however, some differences are also noted, perhaps requiring diagnostic improvement and/or additional physics in the numerical model

  7. Measurement of particle transport coefficients on Alcator C-Mod

    International Nuclear Information System (INIS)

    The goal of this thesis was to study the behavior of the plasma transport during the divertor detachment in order to explain the central electron density rise. The measurement of particle transport coefficients requires sophisticated diagnostic tools. A two color interferometer system was developed and installed on Alcator C-Mod to measure the electron density with high spatial (∼ 2 cm) and high temporal (≤ 1.0 ms) resolution. The system consists of 10 CO2 (10.6 μm) and 4 HeNe (.6328 μm) chords that are used to measure the line integrated density to within 0.08 CO2 degrees or 2.3 x 1016m-2 theoretically. Using the two color interferometer, a series of gas puffing experiments were conducted. The density was varied above and below the threshold density for detachment at a constant magnetic field and plasma current. Using a gas modulation technique, the particle diffusion, D, and the convective velocity, V, were determined. Profiles were inverted using a SVD inversion and the transport coefficients were extracted with a time regression analysis and a transport simulation analysis. Results from each analysis were in good agreement. Measured profiles of the coefficients increased with the radius and the values were consistent with measurements from other experiments. The values exceeded neoclassical predictions by a factor of 10. The profiles also exhibited an inverse dependence with plasma density. The scaling of both attached and detached plasmas agreed well with this inverse scaling. This result and the lack of change in the energy and impurity transport indicate that there was no change in the underlying transport processes after detachment

  8. ICRF heating experiments on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Y.; Bonoli, P.T.; Hubbard, A.; Mazurenko, A.; OShea, P.J.; Porkolab, M.; Reardon, J.; Wukitch, S.; Boivin, R. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Bombarda, F. [Associazione EURATOM-ENEA sulla Fusione, Frascati 00044 (Italy); Fiore, C.; Garnier, D.; Goetz, J.A.; Granetz, R.; Greenwald, M. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Hartmann, D. [Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Hutchinson, I.H.; Irby, J.; LaBombard, B.; Lipschultz, B.; Marmar, E. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); May, M. [Department of Physics, The John Hopkins University, Baltimore, Maryland 21218 (United States); Rice, J.; Rost, J.C.; Schachter, J.; Snipes, J.A.; Stek, P.; Terry, J. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Welch, B. [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742 (United States); Wolfe, S. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

    1997-04-01

    Routine high power operation of the ICRF heating system (up to 3.5 MW at 80 MHz) has enabled studies of enhanced confinement modes as well as high heat flux divertor experiments in the Alcator C-Mod tokamak with toroidal magnetic fields of up to 8 T. H-mode was routinely observed when the edge temperature exceeded a threshold value. Boronization has reduced the radiated power to approximately 30{percent} of the input power, which had little effect on confinement of L-mode plasmas, but had a large impact on the performance of H-mode plasmas. It has become possible to achieve quasi-steady-state H-modes with H{approx_equal}2 and {beta}{sub N}{approx_equal}1.5 simultaneously with P{sub rad}/P{sub in}{approx_equal}0.3 and Z{sub eff}{approx_equal}1.5. PEP mode can be obtained with central ICRF heating combined with core fuelling by pellet injection. Because of the high central density, ion heating becomes the dominant heating channel during PEP mode. For direct electron heating schemes, such as heating by the mode converted ion Bernstein wave, the electron heating profile can be measured using the break-in-slope analysis of the electron temperature at rf power transitions. Mode conversion heating produced highly localized electron heating profiles, both on-axis and off-axis. Recent developments in full-wave codes have improved the agreement between the observed experimental results and the theoretically calculated power absorption profiles and power partition between ions and electrons. {copyright} {ital 1997 American Institute of Physics.}

  9. Measurement of particle transport coefficients on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Luke, T.C.T.

    1994-10-01

    The goal of this thesis was to study the behavior of the plasma transport during the divertor detachment in order to explain the central electron density rise. The measurement of particle transport coefficients requires sophisticated diagnostic tools. A two color interferometer system was developed and installed on Alcator C-Mod to measure the electron density with high spatial ({approx} 2 cm) and high temporal ({le} 1.0 ms) resolution. The system consists of 10 CO{sub 2} (10.6 {mu}m) and 4 HeNe (.6328 {mu}m) chords that are used to measure the line integrated density to within 0.08 CO{sub 2} degrees or 2.3 {times} 10{sup 16}m{sup {minus}2} theoretically. Using the two color interferometer, a series of gas puffing experiments were conducted. The density was varied above and below the threshold density for detachment at a constant magnetic field and plasma current. Using a gas modulation technique, the particle diffusion, D, and the convective velocity, V, were determined. Profiles were inverted using a SVD inversion and the transport coefficients were extracted with a time regression analysis and a transport simulation analysis. Results from each analysis were in good agreement. Measured profiles of the coefficients increased with the radius and the values were consistent with measurements from other experiments. The values exceeded neoclassical predictions by a factor of 10. The profiles also exhibited an inverse dependence with plasma density. The scaling of both attached and detached plasmas agreed well with this inverse scaling. This result and the lack of change in the energy and impurity transport indicate that there was no change in the underlying transport processes after detachment.

  10. Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices

    NARCIS (Netherlands)

    Wright, G. M.; D. Brunner,; Baldwin, M. J.; Bystrov, K.; Doerner, R. P.; Labombard, B.; Lipschultz, B.; De Temmerman, G.; J.L. Terry,; Whyte, D. G.; Woller, K.B.

    2013-01-01

    Growth of tungsten nano-tendrils (“fuzz”) has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a la

  11. Blob sizes and velocities in the Alcator C-Mod scrape-off layer

    DEFF Research Database (Denmark)

    Kube, R.; Garcia, O.E.; LaBombard, B.;

    A new blob-tracking algorithm for the GPI diagnostic installed in the outboard-midplane of Alcator C-Mod is developed. I t tracks large-amplitude fluctuations propagating through the scrape-off layer and calculates blob sizes and velocities. We compare the results of this method to a blob velocity...

  12. TSC [Tokamak Simulation Code] simulations of Alcator C-MOD discharges

    International Nuclear Information System (INIS)

    The axisymmetric stability of the single X-point, nominal Alcator C-MOD configuration is investigated with the Tokamak Simulation Code. The resistive wall passive growth rate, in the absence of feedback stabilization, is obtained. The instability is suppressed with an appropriate active feedback system. 2 refs., 25 figs., 1 tab

  13. Advanced Tokamak Regimes in Alcator C-Mod with Lower Hybrid Current Drive

    Science.gov (United States)

    Parker, R.; Bonoli, P.; Gwinn, D.; Hutchinson, I.; Porkolab, M.; Ramos, J.; Bernabei, S.; Hosea, J.; Wilson, R.

    1999-11-01

    Alcator C-Mod has been proposed as a test-bed for developing advanced tokamak scenarios owing to its strong shaping, relatively long pulse length capability at moderate field, e.g. t ~ L/R at B = 5T and T_eo ~ 7keV, and the availability of strong ICRF heating. We plan to exploit this capability by installing up to 4 MW RF power at 4.6 GHz for efficient off-axis current drive by lower hybrid waves. By launching LH waves with a grill whose n_xx spectrum can be dynamically controlled over the range 2 2. Such reversed or nearly zero shear regimes have already been proposed as the basis of an advanced tokamak burning-plasma experiment-ATBX (M. Porkolab et al, IAEA-CN-69/FTP/13, IAEA,Yokohama 1998.), and could provide the basis for a demonstration power reactor. Theoretical and experimental basis for this advanced tokamak research program on C-Mod, including design of the lower hybrid coupler, its spectrum and current drive capabilities will be presented.

  14. Alcator C-Mod ion cyclotron antenna performance

    International Nuclear Information System (INIS)

    Ion cyclotron range of frequency (ICRF) heating is expected to be an important auxiliary heating source for ITER and fusion reactors. One of the keys to successful ICRF heating is the antenna performance and a number of issues can limit the antenna performance including poor voltage and power handling, impurity production, strong RF plasma edge interactions, poor RF coupling, and localized heating of the antenna structure. High power density antenna operation, with all metal protection tiles and plasma facing components (PFC), present significant challenges to ICRF antenna operation. High performance plasmas can be achieved with all metal PFC's after boronization. In Ohmic H-mode discharges, the plasma performance degradation occurs at a rate 3-4 times slower than RF heated discharges with the similar input energy (discharge integrated). The erosion process also appears to be accelerated for weaker single pass absorption heating scenario, D(3He) on C-Mod. The C-Mod H minority single pass absorption is stronger and is similar to that expected in ITER implying similar RF induced erosion in ITER as on C-Mod. Since Faraday screen-less antenna operation has a number of advantages; the J antenna was operated without a Faraday screen. The voltage and power handling were unaffected by the screen removal. However, the heating effectiveness was 15-20% less and the influx of Cu was identified as the likely cause of the decreased performance. On C-Mod, high density discharges can yield neutral pressures at which antenna operation is prohibited. This neutral pressure limit may be related to phenomena associated with antenna ELM (edge localized mode) interactions. Experiments showed that multipactor can cause a glow discharge at neutral pressures two orders of magnitude below the Paschen breakdown limit. In the presence of a 0.1 T B-field, measurements on the C-Mod antennas showed the presence of a glow discharge at a neutral pressure similar to the observed operational neutral

  15. Status of the neutron diagnostic experiment for Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Fiore, C.L.; Boivin, R.; Granetz, R.S.; Fuller, T.; Kurz, C. (MIT Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States))

    1992-10-01

    The Alcator C-Mod experiment is expected to produce neutrons at a rate of up to 1 {times} 10{sup 16} n/s during its highest performance operation. The global neutron detection system must provide accurate measurement of this production over the full operating regime of the experiment, 10{sup 11}--10{sup 16} n/s. This is accomplished using a series of uranium fission detectors enriched in U{sup 235} of staggered sensitivity. These are distributed in two moderator assemblies. A BF{sub 3} detector is added to each moderator to cover the lowest operational range. Preliminary calibration of the system has been accomplished using a 65.4 {mu}g Cf{sup 252} source placed inside the Alcator C-Mod vacuum vessel. The system design and calibration is discussed herein.

  16. Extended pulse-length operation of Alcator C-Mod

    Science.gov (United States)

    Wolfe, S.; Irby, J.; Terry, J.; Labombard, B.; Wukitch, S.; Marmar, E.; Cochran, W.; Dekow, G.; Gwinn, D.; Maqueda, R.

    2001-10-01

    The C-Mod Advanced Tokamak program depends on the unique capability of the C-Mod facility to operate with plasma pulse lengths corresponding to multiple skin times with high performance parameters. Specifically, pulse lengths with current and toroidal field flattops of order 5 seconds, with toroidal field of 4 tesla, are proposed. In the case of the AT program, these plasmas would have current sustained non-inductively, i.e. by a combination of RF (lower hybrid) current drive and pressure-driven current. Experiments during the 2001 experimental campaign will extend the plasma pulse length to the maximum possible with only inductive current drive. The purpose of these experiments is to test and demonstrate the long-pulse capability of the coils, power system, control system, etc., and to test power and particle handling performance under long pulse conditions. In support of the latter goal, we will benchmark divertor surface heating during medium-power operation and assess the effectiveness of X-point sweeping and N2 puffing for dissipating the divertor heat loads. Results of these experiments will be presented.

  17. ECE Temperature Fluctuations associated with EDA H-Mode discharges in Alcator C-Mod

    Science.gov (United States)

    Phillips, P. E.; Lynn, A. G.

    2006-10-01

    Alcator C-Mod exhibits an ELM-free H-mode with ``enhanced,,lpha'' emission accompanied by a quasi-coherent mode (QCM) edge relaxation mechanism. This steady state H-mode lowers the peak heat load to the diverters which is advantageous for reactor operations. A high-resolution heterodyne electron-cyclotron-emission (ECE) radiometer with 32 channels (δR˜7mm) and a bandwidth up to 1MHz covering the full radius of C-Mod has observed spatial resolved temperature fluctuations that are highly correlated with the edge QCM mode. The QCM mode is also directly observed by the edge ECE channels though the changes in optical depth due to the large density fluctuations in the QCM (˜30%). Details of these measurements will be presented in this poster.

  18. Initial ICRF coupling and heating experiments on Alcator C-Mod

    International Nuclear Information System (INIS)

    Initial ICRF coupling studies were performed successfully on the Alcator C-Mod tokamak with all-metallic first wall, using a radially movable single-current-strap (monopole) antenna. The plasma loading is 10-40 times the vacuum loading, which is sufficient to inject 2MW of r.f. power through one two-strap (dipole) antenna. The observed loading is consistent with predictions of full-wave calculations. Up to 1MW of r.f. power (antenna power density of XXXX10MWm-2) has been injected into the C-Mod plasma without serious impurity problems. Definite signs of both ion and electron heating were observed at power levels of 0.4MW and higher (PRF/POHXXXX0.3) in the D(H) minority heating regime. High-power heating experiments with 4MW of source power and two dipole antennas began in May 1994. ((orig.))

  19. Novel energy resolving x-ray pinhole camera on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Pablant, N. A.; Delgado-Aparicio, L.; Bitter, M.; Ellis, R.; Hill, K. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Brandstetter, S.; Eikenberry, E.; Hofer, P.; Schneebeli, M. [Dectris Ltd., Baden (Switzerland)

    2012-10-15

    A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of Almost-Equal-To 1 cm, an energy resolution of Almost-Equal-To 1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009)] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

  20. Design of a New Optical System for Alcator C-Mod Motional Stark Effect Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jinseok; Scott, Steve; Manfred, Bitter; Lerner, Lerner

    2009-11-12

    The motional Stark effect (MSE) diagnostic on Alcator C-Mod uses an in-vessel optical system (five lenses and three mirrors) to relay polarized light to an external polarimeter because port access limitations on Alcator C-Mod preclude a direct view of the diagnostic beam. The system experiences unacceptable, spurious drifts of order several degrees in measured pitch angle over the course of a run day. Recent experiments illuminated the MSE diagnostic with polarized light of fixed orientation as heat was applied to various optical elements. A large change in measured angle was observed as two particular lenses were heated, indicating that thermal-stress-induced birefringence is a likely cause of the spurious variability. Several new optical designs have been evaluated to eliminate the affected in-vessel lenses and to replace the focusing they provide with curved mirrors; however, ray tracing calculations imply that this method is not feasible. A new approach is under consideration that utilizes in situ calibrations with in-vessel reference polarized light sources. 2008 American Institute of Physics.

  1. ICRF antenna matching system with ferrite tuners for the Alcator C-Mod tokamak

    Science.gov (United States)

    Lin, Y.; Binus, A.; Wukitch, S. J.; Koert, P.; Murray, R.; Pfeiffer, A.

    2015-12-01

    Real-time fast ferrite tuning (FFT) has been successfully implemented on the ICRF antennas on Alcator C-Mod. The former prototypical FFT system on the E-port 2-strap antenna has been upgraded using new ferrite tuners that have been designed specifically for the operational parameters of the Alcator C-Mod ICRF system (˜ 80 MHz). Another similar FFT system, with two ferrite tuners and one fixed-length stub, has been installed on the transmission line of the D-port 2-strap antenna. These two systems share a Linux-server-based real-time controller. These FFT systems are able to achieve and maintain the reflected power to the transmitters to less than 1% in real time during the plasma discharges under almost all plasma conditions, and help ensure reliable high power operation of the antennas. The innovative field-aligned (FA) 4-strap antenna on J-port has been found to have an interesting feature of loading insensitivity vs. plasma conditions. This feature allows us to significantly improve the matching for the FA J-port antenna by installing carefully designed stubs on the two transmission lines. The reduction of the RF voltages in the transmission lines has enabled the FA J-port antenna to deliver 3.7 MW RF power to plasmas out of the 4 MW source power in high performance I-mode plasmas.

  2. Second Harmonics of Reversed Shear TAE in Alcator C-Mod Geometry

    Science.gov (United States)

    Chen, Eugene; Berk, Herbert; Breizman, Boris; Zheng, Linjin

    2009-11-01

    Experiments on Alcator C-Mod, operating with reversed magnetic shear, reveal Toroidal Alfven Eigenmodes (TAE) together with signals at twice the mode frequency. The double frequency signals can be viewed as second harmonic sidebands driven by quadratic non-linear terms in the MHD equations, in analogy with a corresponding theory for Alfven Cascades [1]. However, these nonlinear sidebands have not yet been quantified by any of the existing codes. In this work, we extend AEGIS code [2] to capture nonlinear effects iteratively by treating the nonlinear terms as a driving source in the linear MHD solver. We first compute the TAE mode structure for realistic geometry and q-profile and then use it to find the spatial structure of the second harmonic density perturbation, which can be directly compared with PCI measurements at Alcator C-Mod. [1] H. Smith, B. N. Breizman, M. Lisak and D. Anderson, Physics of Plasmas 13 042504 (2006) [2] L. J. Zheng and M. Kotschenreuther, Journal of Computational Physics 211 (2006) 748-766

  3. Long Term Retention of Deuterium and Tritium in Alcator C-Mod

    International Nuclear Information System (INIS)

    We estimate the total in-vessel deuterium retention in Alcator C-Mod from a run campaign of about 1090 plasmas. The estimate is based on measurements of deuterium retained on 22 molybdenum tiles from the inner wall and divertor. The areal density of deuterium on the tiles was measured by nuclear reaction analysis. From these data, the in-vessel deuterium inventory is estimated to be about 0.1 gram, assuming the deuterium coverage is toroidally symmetric. Most of the retained deuterium is on the walls of the main plasma chamber, only about 2.5% of the deuterium is in the divertor. The D coverage is consistent with a layer saturated by implantation with ions and charge-exchange neutrals from the plasma. This contrasts with tokamaks with carbon plasma-facing components (PFC's) where long-term retention of tritium and deuterium is large and mainly in the divertor due to codeposition with carbon eroded by the plasma. The low deuterium retention in the C-Mod divertor is mainly due to the absence of carbon PFC's in C-Mod and the low erosion rate of Mo

  4. Study of the Effects of Neutrals in Alcator C-Mod Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R L; Boswell, C; Goetz, J A; Hubbard, A E; Irby, J; LaBombard, B; Marmar, E S; Mossessian, D; Owen, L W; Pitcher, C S; Terry, J L

    1999-06-14

    Recently, much effort has been dedicated to understanding the bifurcation involved in the transition from a low to high confinement regime. While several theories have been brought forward, many factors remain to be elucidated, one of which involves the role played by neutral particles in the evolution of a transport barrier near the edge of the plasma. Alcator C-Mod is especially well suited for the study of neutral particle effects, mainly because of its high plasma and neutral densities, and closed divertor geometry. Alcator C-Mod employs ICRF as auxiiiary heating for obtaining a high confinement regime, although ohmic H-modes are routinely obtained as well. The neutrals can enter the edge dynamics through the particle, momentum and energy balance. In the particle balance, the source of neutrals has to be evaluated vis-8-vis the formation of the edge density pedestal. It is widely believed that plasma rotation is an important factor in reducing transport. In this case, neutrals could act as a momentum sink, through the charge-exchange process. That same process can also modify the energy balance of the plasma near the edge by increasing the cross-field heat flux. These effects are quite difficult to measure experimentally, in large part because neutral particle diagnosis is not an easy task, and because of the inherent 3-dimensional aspect of the problem. Consequently, the neutral's spatial and energy distributions are usually not well known. In Alcator C-Mod, we recently implemented a series of diagnostics for the purpose of measuring these distributions. They include measurements of the neutral pressure at many locations around the tokamak, and spatially resolved measurements of Lyman-a and charge-exchange power emission. A high-resolution multichord (20 channels) tangential view of neutral deuterium emission (Lyman-a) has been recently installed near the midplane. The viewing area covers approximately 4 cm across the separatrix, with a nominal 2 mm

  5. Neutral particle analysis of ICRF heated discharges on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W D; Boivin, R L; Bonoli, P T; Fiore, C L; Hubbard, A; Irby, J; Nelson-Melby, E; Porkolab, M; Wukitch, S J [NW17-121 MIT-PSFC Massachusetts Institute of Technology, 175 Albany Street, Cambridge, MA 02139 (United States)

    2003-08-01

    A neutral particle analyser (NPA) has been used to make measurements of the ion distribution in the Alcator C-Mod tokamak. We have used the analyser to measure the energy distribution of majority deuterons and minority hydrogen (up to 20 keV) at 0.4{<=}r/a{<=}0.6, during minority ion cyclotron range of frequencies (ICRF) heating. These energy spectra were also simulated by using the predicted minority ion distribution from a combined Fokker Planck ICRF code in a model for the neutral particle flux. The model predictions for neutral flux were found to be in qualitative agreement with the measured energy spectra. The energy spectra for two different ICRF antenna configurations were also measured and found to be very similar.

  6. High resolution measurements of neutral density and ionization rate in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R. L.; Hughes, J. W.; LaBombard, B.; Mossessian, D.; Terry, J. L.

    2001-01-01

    Two new high resolution detectors have been installed on the Alcator C-Mod tokamak to measure the neutral density and ionization rate at the edge of the main chamber plasma. Using a silicon detector sensitive to UV light, and a very narrow filter with transmission peaking at 1216 Aa, the Lyman alpha radiation emanating from neutral deuterium (and hydrogen) is measured. The detectors consist of 20 channel arrays which view the plasma tangentially 12.5 cm below the outer midplane, and 10 cm above the inner midplane. The imaging is performed using a 1mmx3mm slit, which gives a nominal radial resolution of 2 and 3 mm, respectively. The local emissivity is obtained via a standard Abel inversion technique. Employing well-known branching ratios, and using measured local electron density and temperature, the neutral density and ionization rate are inferred with similar radial resolution. Details of the setup and sensitivity of the results to plasma conditions are discussed.

  7. Divertor heat flux footprints in EDA H-mode discharges on Alcator C-Mod

    International Nuclear Information System (INIS)

    The physics that sets the width of the power exhaust channel in a tokamak scrape-off layer and its scaling with engineering parameters is of fundamental importance for reactor design, yet it remains to be understood. An extensive array of divertor heat flux diagnostics was recently commissioned in Alcator C-Mod with the aim of improving our understanding. Initial results are reported from EDA H-mode discharges in which plasma current, input power, toroidal field and magnetic topology were varied. The integral width of the outer divertor heat flux footprint is found to lie in the range of 3-5 mm mapped to the mid-plane. Widths are insensitive to single versus double-null topology and the magnitude of toroidal field. Pedestal physics appears to largely determine these widths; a dependence of width on plasma thermal energy is noted, yielding a reduction in width as plasma current is increased for the best EDA H-modes.

  8. Divertor heat flux footprints in EDA H-mode discharges on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    LaBombard, B., E-mail: labombard@psfc.mit.edu [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Terry, J.L.; Hughes, J.W.; Brunner, D.; Payne, J.; Reinke, M.L.; Lin, Y.; Wukitch, S. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2011-08-01

    The physics that sets the width of the power exhaust channel in a tokamak scrape-off layer and its scaling with engineering parameters is of fundamental importance for reactor design, yet it remains to be understood. An extensive array of divertor heat flux diagnostics was recently commissioned in Alcator C-Mod with the aim of improving our understanding. Initial results are reported from EDA H-mode discharges in which plasma current, input power, toroidal field and magnetic topology were varied. The integral width of the outer divertor heat flux footprint is found to lie in the range of 3-5 mm mapped to the mid-plane. Widths are insensitive to single versus double-null topology and the magnitude of toroidal field. Pedestal physics appears to largely determine these widths; a dependence of width on plasma thermal energy is noted, yielding a reduction in width as plasma current is increased for the best EDA H-modes.

  9. High resolution bolometry on the Alcator C-Mod tokamak (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R.L.; Goetz, J.A.; Marmar, E.S.; Rice, J.E.; Terry, J.L. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, 175 Albany Street, Cambridge, Massachusetts 02139 (United States)

    1999-01-01

    Recent breakthroughs in silicon detector technology now permit measurement of radiated power over a wide range in photon energies. These detectors (also known as AXUV photodiodes) have a flat spectral power response from ultraviolet to x-ray energies, and with a slightly reduced efficiency all the way down to visible wavelengths. Since they can be made small, multichannel detectors allow high spatial resolution to be combined with an intrinsic high temporal resolution, which can reach the microsecond range, depending on the application. Additional features include ease of use and installation, and relatively low cost compared to other techniques. A combination of two multichannel toroidally viewing systems has been recently installed on the Alcator C-Mod tokamak. The first array, which is composed of 16 channels, sees tangentially the outer-half of the plasma at the midplane, and is used to measure the total power radiated. The second array, also located at the midplane, consists of 19 channels and views the edge of the plasma. This array has a 2 mm radial resolution, allowing, for example, the study of edge dynamics in high confinement (H mode) plasmas. Because these detectors are largely insensitive to neutral particles (at least at particle energies of interest), it is now possible to measure the radial distribution of neutral {open_quotes}radiated{close_quotes} power emissivity, by looking at the difference between these measurements and those obtained with standard bolometers. When neutrals are not important, we found a very good agreement between the AXUV detectors and standard bolometers. Examples of applications of these measurements to the study of edge H-mode dynamics, impurity injection, disruptions, and internal barrier formation, are described. Planned upgrades and new applications for Alcator C-Mod are also discussed. {copyright} {ital 1999 American Institute of Physics.}

  10. Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas

    Science.gov (United States)

    Mikkelsen, D. R.; Bitter, M.; Delgado-Aparicio, L.; Hill, K. W.; Greenwald, M.; Howard, N. T.; Hughes, J. W.; Rice, J. E.; Reinke, M. L.; Podpaly, Y.; Ma, Y.; Candy, J.; Waltz, R. E.

    2015-06-01

    Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors could produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will enable planning to optimize these impacts. We show that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We find that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority D and minority H ions (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.

  11. Neutral Transport Simulations of Gas Puff Imaging Experiments on Alcator C-Mod

    International Nuclear Information System (INIS)

    Visible imaging of gas puffs has been used on the Alcator C-Mod tokamak to characterize edge plasma turbulence, yielding data that can be compared with plasma turbulence codes. Simulations of these experiments with the DEGAS 2 Monte Carlo neutral transport code have been carried out to explore the relationship between the plasma fluctuations and the observed light emission. By imposing two-dimensional modulations on the measured time-average plasma density and temperature profiles, we demonstrate that the spatial structure of the emission cloud reflects that of the underlying turbulence. However, the photon emission rate depends on the plasma density and temperature in a complicated way, and no simple scheme for inferring the plasma parameters directly from the light emission patterns is apparent. The simulations indicate that excited atoms generated by molecular dissociation are a significant source of photons, further complicating interpretation of the gas puff imaging results.Visibl e imaging of gas puffs has been used on the Alcator C-Mod tokamak to characterize edge plasma turbulence, yielding data that can be compared with plasma turbulence codes. Simulations of these experiments with the DEGAS 2 Monte Carlo neutral transport code have been carried out to explore the relationship between the plasma fluctuations and the observed light emission. By imposing two-dimensional modulations on the measured time-average plasma density and temperature profiles, we demonstrate that the spatial structure of the emission cloud reflects that of the underlying turbulence. However, the photon emission rate depends on the plasma density and temperature in a complicated way, and no simple scheme for inferring the plasma parameters directly from the light emission patterns is apparent. The simulations indicate that excited atoms generated by molecular dissociation are a significant source of photons, further complicating interpretation of the gas puff imaging results

  12. Spectroscopic measurement of impurity transport coefficients and penetration efficiencies in Alcator C-Mod plasmas

    Science.gov (United States)

    Graf, M. A.; Rice, J. E.; Terry, J. L.; Marmar, E. S.; Goetz, J. A.; McCracken, G. M.; Bombarda, F.; May, M. J.

    1995-01-01

    Impurity transport coefficients and the penetration efficiencies of intrinsic and injected impurities through the separatrix of diverted Alcator C-Mod discharges have been measured using x-ray and vacuum ultraviolet (VUV) spectroscopic diagnostics. The dominant low Z intrinsic impurity in C-Mod is carbon which is found to be present in concentrations of less than 0.5%. Molybdenum, from the plasma facing components, is the dominant high Z impurity and is typically found in concentrations of about 0.02%. Trace amounts of medium and high Z nonrecycling impurities can be injected at the midplane using the laser blow-off technique and calibrated amounts of recycling, gaseous impurities can be introduced through fast valves either at the midplane or at various locations in the divertor chamber. A five chord crystal x-ray spectrometer array with high spectral resolution is used to provide spatial profiles of high charge state impurities. An absolutely calibrated, grazing incidence VUV spectrograph with high time resolution and a broad spectral range allows for the simultaneous measurement of many impurity lines. Various filtered soft x-ray diode arrays allow for spatial reconstructions of plasma emissivity. The observed brightnesses and emissivities from a number of impurity lines are used together with the mist transport code and a collisional-radiative atomic physics model to determine charge state density profiles and impurity transport coefficients. Comparisons of the deduced impurity content with the measured Zeff and total radiated power of the plasma are made.

  13. The Submillimeter Wave Electron Cyclotron Emission Diagnostic for the Alcator C-Mod Tokamak.

    Science.gov (United States)

    Hsu, Thomas C.

    This thesis describes the engineering design, construction, and operation of a high spatial resolution submillimeter wave diagnostic for electron temperature measurements on Alcator C-Mod. Alcator C-Mod is a high performance compact tokamak capable of producing diverted, shaped plasmas with a major radius of 0.67 meters, minor radius of 0.21 centimeters, plasma current of 3 MA. The maximum toroidal field is 9 Tesla on the magnetic axis. The ECE diagnostic includes three primary components: a 10.8 meter quasioptical transmission line, a rapid scanning Michelson interferometer, and a vacuum compatible calibration source. Due to the compact size and high field of the tokamak the ECE system was designed to have a spectral range from 100 to 1000 GHz with frequency resolution of 5 GHz and spatial resolution of one centimeter. The beamline uses all reflecting optical elements including two off-axis parabolic mirrors with diameters of 20 cm. and focal lengths of 2.7 meters. Techniques are presented for grinding and finishing the mirrors to sufficient surface quality to permit optical alignment of the system. Measurements of the surface figure confirm the design goal of 1/4 wavelength accuracy at 1000 GHz. Extensive broadband tests of the spatial resolution of the ECE system are compared to a fundamental mode Gaussian beam model, a three dimensional vector diffraction model, and a geometric optics model. The Michelson interferometer is a rapid scanning polarization instrument which has an apodized frequency resolution of 5 GHz and a minimum scan period of 7.5 milliseconds. The novel features of this instrument include the use of precision linear bearings to stabilize the moving mirror and active counterbalancing to reduce vibration. Beam collimation within the instrument is done with off-axis parabolic mirrors. The Michelson also includes a 2-50 mm variable aperture and two signal attenuators constructed from crossed wire grid polarizers. To make full use of the advantages

  14. Mode conversion electron heating in Alcator C-Mod: Theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bonoli, P. T. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Brambilla, M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Nelson-Melby, E. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Phillips, C. K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Porkolab, M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Schilling, G. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Taylor, G. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Wukitch, S. J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Boivin, R. L. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Boswell, C. J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] (and others)

    2000-05-01

    Localized electron heating [full width at half maximum of {delta}(r/a){approx_equal}0.2] by mode converted ion Bernstein waves (IBW) has been observed in the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. These experiments were performed in D({sup 3}He) plasmas at high magnetic field (B{sub 0}=7.9 T), high-plasma density (n{sub e0}{>=}1.5x10{sup 20} m{sup -3}), and for 0.05{<=}n{sub He-3}/n{sub e}{<=}0.30. Electron heating profiles of the mode converted IBW were measured using a break in slope analysis of the electron temperature versus time in the presence of rf (radio frequency) modulation. The peak position of electron heating was found to be well-correlated with {sup 3}He concentration, in agreement with the predictions of cold plasma theory. Recently, a toroidal full-wave ion cyclotron range of frequencies (ICRF) code TORIC [M. Brambilla, Nucl. Fusion 38, 1805 (1998)] was modified to include the effects of IBW electron Landau damping at (k{sub (perpendicular} {sub sign)}{rho}{sub i}){sup 2}>>1, This model was used in combination with a 1D (one-dimensional) integral wave equation code METS [D. N. Smithe et al., Radio Frequency Power in Plasmas, AIP Conf. Proc. 403 (1997), p. 367] to analyze these experiments. Model predictions were found to be in qualitative and in some instances quantitative agreement with experimental measurements. A model for mode conversion current drive (MCCD) has also been developed which combines a toroidal full wave code with an adjoint evaluation of the ICRF current drive efficiency. Predictions for off-axis MCCD in C-Mod have been made using this model and will be described. (c) 2000 American Institute of Physics.

  15. The development of an Omegratron plasma ion mass spectrometer for Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, E.E. Jr.

    1993-05-01

    A new diagnostic device, the Omegatron Probe, has been developed to investigate relative impurity levels and impurity charge state distribution in the Alcator C-Mod Tokamak edge plasma. The Omegatron probe consists of two principal components, a ``front-end`` of independently biased grids, arranged in a gridded energy analyzer fashion and a large collection cavity. Particles enter the probe in a thin ``ribbon`` through a knife-edge slit. The grids provide a means to measure and control the parallel energy distribution of the ions. In the collection cavity, an oscillating electric field is applied perpendicularly to the ambient magnetic field. Ions whose cyclotron frequencies are resonant with this electric field oscillation will gain perpendicular energy and be collected. In this way, the probe can be operated in two modes: first, by fixing the potentials on the grids and sweeping frequencies to obtain a `` Z/m spectrum`` of ion species and second, by fixing the frequency and sweeping the grid potentials to obtain the distribution function of an individual impurity species. The Omegatron probe performed successfully in tests on a Hollow Cathode Discharge (HCD) linear plasma column. It obtained measurements of T{sub e} {approx} 5 eV, T{sub i} (H{sup +}) {approx} 2.0 {plus_minus} 0.2 eV, n{sub 0} {approx} 9 {times} 10{sup 15} m{sup {minus}3}, RMS potential fluctuation levels of {approximately} 0.5 {plus_minus} 0.05 {plus_minus} T{sub e}, and obtained ``Z/m`` spectra for the plasma ions (H{sup +}, H{sub 2}{sup +}, He{sup +}). Additional experiments confirmed the theoretical scalings of the f/{delta}f resolution with the applied electric field and magnetic field strengths. The instrument yielded an absolute level of resolution, f/{delta}f, of approximately 2.5 to 3 times the theoretical values. Finally, the results from the HCD are used to project operation on Alcator C-Mod.

  16. Molybdenum emission from impurity-induced m= 1 snake-modes on the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Aparicio, L. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); MIT - Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Bitter, M.; Gates, D.; Hill, K.; Pablant, N. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Granetz, R.; Reinke, M.; Podpaly, Y.; Rice, J. [MIT - Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Beiersdorfer, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Sugiyama, L. [MIT - Laboratory for Nuclear Science, Cambridge, Massachusetts 02139 (United States)

    2012-10-15

    A suite of novel high-resolution spectroscopic imaging diagnostics has facilitated the identification and localization of molybdenum impurities as the main species during the formation and lifetime of m= 1 impurity-induced snake-modes on Alcator C-Mod. Such measurements made it possible to infer, for the first time, the perturbed radiated power density profiles from which the impurity density can be deduced.

  17. Upgrade to the Gas Puff Imaging Diagnostic that Views Alcator C-Mod's Inboard Edge

    Science.gov (United States)

    Sierchio, J. M.; Terry, J. L.

    2012-10-01

    We describe an upgrade of Alcator C-Mod's Gas Puff Imaging system which views the inboard plasma edge and SOL along lines-of-sight that are approximately parallel to the local magnetic field. The views are arranged in a 2D (R,Z) array with ˜2.8 cm radial coverage and ˜2.4 cm poloidal coverage. 23 of 54 available views were coupled via fibers to individual interference filters and PIN photodiode detectors. We are in the process of upgrading the system in order to increase the sensitivity of the system by replacing the PIN photodiodes with a 4x8 array of Avalanche Photo-Diodes (APD). Light from 30 views is coupled to the single-chip APD array through a single interference filter. We expect an improvement in signal-to-noise ratio of more than 10x. The frequency response of the system will increase from ˜400 kHz to 1MHz. The dynamic range of the new system is manipulated by changing the high-voltages on the APDs. Test results of the detectors' channel-to-channel cross-talk, frequency response, and gain curves will be presented, along with schematics of the experimental setup. The upgraded system allows for more study of inboard edge fluctuations, including whether the quasi-coherent fluctuations observed in the outboard edge also exist inboard.

  18. The dynamics and structure of edge-localized-modes in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Terry, J.L. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States)]. E-mail: terry@psfc.mit.edu; Cziegler, I. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Hubbard, A.E. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Snipes, J.A. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Hughes, J.W. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Greenwald, M.J. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); LaBombard, B. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Lin, Y. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Phillips, P. [Fusion Research Center, University of Texas-Austin, Austin, TX 78712 (United States); Wukitch, S. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States)

    2007-06-15

    Characteristics of discrete ELMs produced in Alcator C-Mod discharges of low edge collisionality (0.2 < {nu} {sup *} < 1) and large lower triangularity ({delta} {sub lower} {approx} 0.75) are examined. The energy lost per ELM from the H-mode pedestal is {approx}10% of the pedestal energy. These ELMs exhibit relatively long-lived precursor oscillations, often with two modes of intermediate toroidal mode number present. At the ELM 'crash' multiple plasma filament structures are expelled into the scrape-off-layer. A short-lived high frequency ({approx}0.5 MHz) magnetic oscillation is initiated at the 'crash'. The initial ELM filaments are large perturbations to the SOL with radial extents of 0.5-1 cm and typical radial propagation velocities of 1 km/s. Velocities of up to 8 km/s have been seen. The poloidal extent of the initial filaments is >4.5 cm. The initial filaments are followed (at intervals of {approx}100 {mu}s) by multiple, less perturbing secondary filaments.

  19. Characterization of enhanced D{alpha} high-confinement modes in Alcator {ital C}-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Greenwald, M.; Boivin, R.; Bonoli, P.; Budny, R.; Fiore, C.; Goetz, J.; Granetz, R.; Hubbard, A.; Hutchinson, I.; Irby, J.; LaBombard, B.; Lin, Y.; Lipschultz, B.; Marmar, E.; Mazurenko, A.; Mossessian, D.; Sunn Pedersen, T.; Pitcher, C.S.; Porkolab, M.; Rice, J.; Rowan, W.; Snipes, J.; Schilling, G.; Takase, Y.; Terry, J.; Wolfe, S.; Weaver, J.; Welch, B.; Wukitch, S. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

    1999-05-01

    Regimes of high-confinement mode have been studied in the Alcator {ital C}-Mod tokamak [Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)]. Plasmas with no edge localized modes (ELM-free) have been compared in detail to a new regime, enhanced D{alpha} (EDA). EDA discharges have only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus EDA discharges do not accumulate impurities and typically have a lower fraction of radiated power. The edge gradients in EDA seem to be relaxed by a continuous process rather than an intermittent one as is the case for standard ELMy discharges and thus do not present the first wall with large periodic heat loads. This process is probably related to fluctuations seen in the plasma edge. EDA plasmas are more likely at low plasma current (q{gt}3.7), for moderate plasma shaping, (triangularity {approximately}0.35{endash}0.55), and for high neutral pressures. As observed in soft x-ray emission, the pedestal width is found to scale with the same parameters that determine the EDA/ELM-free boundary. {copyright} {ital 1999 American Institute of Physics.}

  20. Investigation of performance limiting phenomena in a variable phase ICRF antenna in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Wukitch, S J [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Boivin, R L [General Atomics, San Diego, CA 92186 (United States); Bonoli, P T [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Goetz, J A [University of Wisconsin, Madison, WI 53706 (United States); Irby, J [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Hutchinson, I [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Lin, Y [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Parisot, A [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Porkolab, M [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Marmar, E [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Schilling, G [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Wilson, J R [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States)

    2004-09-01

    High power density, phased antenna operation can often be limited by antenna voltage handling and/or impurity and density production. Using a pair of two-strap antennas for comparison, the performance of a four-strap, fast wave antenna is assessed for a variety of configurations and antenna phases in Alcator C-Mod. To obtain robust voltage handling, the antenna was reconfigured to eliminate regions where the RF E-field is parallel to B or to reduce the RF E-field to <1.0 MV m{sup -1}. To limit impurity generation, BN tiles were used to replace the original Mo tiles, a BN clad septum was inserted to limit field line connection length, and BN-metal interfaces were shielded from the plasma. With these modifications, the antenna heating efficiency and impurity generation are nearly identical to those of the two-strap antennas and independent of antenna phase in L-mode discharges. This antenna has achieved 11 MW m{sup -2} in both heating and current drive phases in both L-mode and H-mode discharges.

  1. Measurements of the high confinement mode pedestal region on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, A.E.; Boivin, R.L.; Granetz, R.S.; Greenwald, M.; Hutchinson, I.H.; Irby, J.H.; In, Y.; Kesner, J.; LaBombard, B.; Lin, Y.; Rice, J.E.; Sunn Pedersen, T.; Snipes, J.A.; Stek, P.C.; Takase, Y.; Wolfe, S.M.; Wukitch, S. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1998-05-01

    Measurements of the steep transport barrier at the edge of the Alcator C-Mod tokamak [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)] are presented. The parameters at the top of this barrier are in the range T{sub e}=150{endash}750 eV and n{sub e}=0.5{minus}3.3{times}10{sup 20} m{sup {minus}3}, depending on the confinement regime. Type III edge localized modes (ELMs) have an upper temperature limit. T{sub e} pedestal profiles show a barrier width {Delta}{sub T}{approx_equal}8 mm. Soft x-ray emissivity profiles are narrower, with {Delta}=2{endash}4 mm. Edge currents are calculated to alter the ideal stability boundary favorably, leading to ideally stable pedestal profiles. High frequency, broadband, edge density fluctuations are sometimes observed in H-mode (high-confinement mode) and are associated with enhanced particle transport. Coherent magnetic fluctuations localized near the pedestal are also seen. {copyright} {ital 1998 American Institute of Physics.}

  2. Analysis of 4-strap ICRF Antenna Performance in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    G. Schilling; S.J. Wukitch; R.L. Boivin; J.A. Goetz; J.C. Hosea; J.H. Irby; Y. Lin; A. Parisot; M. Porkolab; J.R. Wilson; the Alcator C-Mod Team

    2003-07-31

    A 4-strap ICRF antenna was designed and fabricated for plasma heating and current drive in the Alcator C-Mod tokamak. Initial upgrades were carried out in 2000 and 2001, which eliminated surface arcing between the metallic protection tiles and reduced plasma-wall interactions at the antenna front surface. A boron nitride septum was added at the antenna midplane to intersect electric fields resulting from radio-frequency sheath rectification, which eliminated antenna corner heating at high power levels. The current feeds to the radiating straps were reoriented from an E||B to E parallel B geometry, avoiding the empirically observed {approx}15 kV/cm field limit and raising antenna voltage holding capability. Further modifications were carried out in 2002 and 2003. These included changes to the antenna current strap, the boron nitride tile mounting geometry, and shielding the BN-metal interface from the plasma. The antenna heating efficiency, power, and voltage characteristics under these various configurations will be presented.

  3. Upgrades to the 4-strap ICRF Antenna in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    G. Schilling; J.C. Hosea; J.R. Wilson; W. Beck; R.L. Boivin; P.T. Bonoli; D. Gwinn; W.E. Lee; E. Nelson-Melby; M. Porkolab; R. Vieira; S.J. Wukitch; and J.A. Goetz

    2001-06-12

    A 4-strap ICRF antenna suitable for plasma heating and current drive has been designed and fabricated for the Alcator C-Mod tokamak. Initial operation in plasma was limited by high metallic impurity injection resulting from front surface arcing between protection tiles and from current straps to Faraday shields. Antenna modifications were made in February 2000, resulting in impurity reduction, but low-heating efficiency was observed when the antenna was operated in its 4-strap rather than a 2-strap configuration. Further modifications were made in July 2000, with the installation of BN plasma-facing tiles and radio- frequency bypassing of the antenna backplane edges and ends to reduce potential leakage coupling to plasma surface modes. Good heating efficiency was now observed in both heating configurations, but coupled power was limited to 2.5 MW in H-mode, 3 MW in L-mode, by plasma-wall interactions. Additional modifications were started in February 2001 and will be completed by this meeting. All the above upgrades and their effect on antenna performance will be presented.

  4. Effects of neutral particles on edge dynamics in Alcator C-Mod plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R. L. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Goetz, J. A. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hubbard, A. E. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hughes, J. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hutchinson, I. H. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Irby, J. H. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); LaBombard, B. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Marmar, E. S. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Mossessian, D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Pitcher, C. S. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] (and others)

    2000-05-01

    Neutral particle densities and energy losses have been measured in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. Their effect on the formation and evolution of the edge barrier which accompanies the enhanced confinement regime are discussed. The neutrals can enter the edge dynamics through the particle, momentum, and energy balance. Neutral densities of up to 5x10{sup 16} m{sup -3} have been measured in the edge barrier region. Neutrals enter the local dynamics around most of the periphery, not just at the X-point. High resolution measurements of the ionization profile have been obtained for the region near the separatrix. The profile shifts inside the separatrix as the plasma is making a transition from low-to high-mode confinement (H-mode) regimes, partly accounting for the dramatic rise in edge density. The measured neutral density is large enough to affect the bulk ion momentum by charge exchange, and thereby introduces a negative radial electric field at the edge. At the same time, significant edge heat flux, carried by the neutrals, contributes to the measured power loss. At very high edge densities, this loss mechanism could contribute to quenching H-modes. (c) 2000 American Institute of Physics.

  5. High resolution visible continuum imaging diagnostic on the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Marmar, E. S.; Boivin, R. L.; Granetz, R. S.; Hughes, J. W.; Lipschultz, B.; McCool, S.; Mossessian, D.; Pitcher, C. S.; Rice, J. E.; Terry, J. L.

    2001-01-01

    A high spatial resolution CCD based one-dimensional imaging system to measure visible continuum emissivity profiles from Alcator C-Mod tokamak plasmas is described. The instrument has chordal resolution that is better than 1 mm for the edge region of the plasma, where very sharp (1 to 10 mm) gradient lengths in plasma parameters are observed after the formation of the H-mode transport barrier. Each image has up to 2048 pixels, and total spatial coverage goes from 2 cm inside of the magnetic axis to {approx}4 cm outside of the last closed flux surface in the {approx}22 cm horizontal minor radius plasmas. Time resolution can be varied from 0.21 ms to 4 ms; good signal to noise is achieved with 1 ms integration under typical plasma conditions. The emission over most of the plasma volume is dominated by free--free bremsstrahlung, and can be used to infer local values of the average ion charge (Z{sub eff}). Toroidally localized puffing of deuterium, nitrogen, and helium reveals that a significant contribution to the signal in the scrape-off layer at the extreme edge of the plasma can come from diatomic molecular band pseudocontinuum emission.

  6. Scaling and transport analysis of divertor conditions on the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    LaBombard, B.; Goetz, J.; Kurz, C.; Jablonski, D.; Lipschultz, B.; McCracken, G.; Niemczewski, A.; Boivin, R.L.; Bombarda, F.; Christensen, C.; Fairfax, S.; Fiore, C.; Garnier, D.; Graf, M.; Golovato, S.; Granetz, R.; Greenwald, M.; Horne, S.; Hubbard, A.; Hutchinson, I.; Irby, J.; Kesner, J.; Luke, T.; Marmar, E.; May, M.; O`Shea, P.; Porkolab, M.; Reardon, J.; Rice, J.; Schachter, J.; Snipes, J.; Stek, P.; Takase, Y.; Terry, J.; Tinios, G.; Watterson, R.; Welch, B.; Wolfe, S. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1995-06-01

    Detailed measurements and transport analysis of divertor conditions in Alcator C-Mod [Phys. Plasmas {bold 1}, 1511 (1994)] are presented for a range of line-averaged densities, 0.7{lt}{ital {bar n}}{sub {ital e}}{lt}2.2{times}10{sup 20} m{sup {minus}3}. Three parallel heat transport regimes are evident in the scrape-off layer: sheath-limited conduction, high-recycling divertor, and detached divertor, which can coexist in the same discharge. {ital Local} cross-field pressure gradients are found to scale simply with a {ital local} electron temperature. This scaling is consistent with classical electron parallel conduction being balanced by anomalous cross-field transport ({chi}{sub {perpendicular}}{similar_to}0.2 m{sup 2} s{sup {minus}1}) proportional to the local pressure gradient. A 60%--80% of divertor power is radiated in attached discharges, approaching 100% in detached discharges. Detachment occurs when the heat flux to the plate is low and the plasma pressure is high ({ital T}{sub {ital e}}{similar_to}5 eV). High neutral pressures in the divertor are nearly always present (1--20 mTorr), sufficient to remove parallel momentum via ion--neutral collisions.

  7. Measurement of LHCD edge power deposition through modulation techniques on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Faust, I. C.; Brunner, D.; LaBombard, B.; Parker, R. R.; Baek, S. G.; Chilenksi, M. A.; Hubbard, A.; Hughes, J. W.; Terry, J. L.; Shiraiwa, S.; Walk, J. R.; Wallace, G. M.; Whyte, D. G. [MIT Plasma Science and Fusion Center, Cambridge, MA USA (United States); Edlund, E. [Princeton Plasma Physics Laboratory, Princeton, NJ USA (United States)

    2015-12-10

    The efficiency of LHCD on Alcator C-Mod drops exponentially with line average density. At reactor relevant densities (> 1 · 1020 [m{sup −3}]) no measurable current is driven. While a number of causes have been suggested, no specific mechanism has been shown to be responsible for the loss of current drive at high density. Fast modulation of the LH power was used to isolate and quantify the LHCD deposition within the plasma. Measurements from these plasmas provide unique evidence for determining a root cause. Modulation of LH power in steady plasmas exhibited no correlated change in the core temperature. A correlated, prompt response in the edge suggests that the loss in efficiency is related to a edge absorption mechanism. This follows previous results which found the generation of n{sub ||}-independent SOL currents. Multiple Langmuir probe array measurements of the conducted heat conclude that the lost power is deposited near the last closed flux surface. The heat flux induced by LH waves onto the outer divertor is calculated. Changes in the neutral pressure, ionization and hard X-ray emission at high density highlight the importance of the active divertor in the loss of efficiency. Results of this study implicate a mechanism which may occur over multiple passes, leading to power absorption near the LCFS.

  8. Upgrades to the 4-strap ICRF antenna in Alcator C-Mod

    Science.gov (United States)

    Schilling, G.; Hosea, J. C.; Wilson, J. R.; Beck, W.; Boivin, R. L.; Bonoli, P. T.; Gwinn, D.; Lee, W. D.; Nelson-Melby, E.; Porkolab, M.; Vieira, R.; Wukitch, S. J.; Goetz, J. A.

    2001-10-01

    A 4-strap ICRF antenna suitable for plasma heating and current drive has been designed and fabricated for the Alcator C-Mod tokamak. Initial operation in plasma was limited by high metallic impurity injection resulting from front surface arcing between protection tiles and from current straps to Faraday shields. Antenna modifications were made in 2/2000, resulting in impurity reduction, but low heating efficiency was observed when the antenna was operated in its 4-strap rather than a 2-strap configuration. Further modifications were made in 7/2000, with the installation of BN plasma-facing tiles and radiofrequency bypassing of the antenna backplane edges and ends to reduce potential leakage coupling to plasma surface modes. Good heating efficiency was now observed in both heating configurations, but coupled power was limited to 2.5 MW in H-mode, 3 MW in L-mode, by plasma-wall interactions. Additional modifications were started in 2/2001 and will be completed by this meeting. All the above upgrades and their effect on antenna performance will be presented.

  9. Robotic calibration of the motional Stark effect diagnostic on Alcator C-Mod

    Science.gov (United States)

    Mumgaard, Robert T.; Scott, Steven D.; Ko, Jinseok

    2014-05-01

    The capability to calibrate diagnostics, such as the Motional Stark Effect (MSE) diagnostic, without using plasma or beam-into-gas discharges will become increasingly important on next step fusion facilities due to machine availability and operational constraints. A robotic calibration system consisting of a motorized three-axis positioning system and a polarization light source capable of generating arbitrary polarization states with a linear polarization angle accuracy of deployed on Alcator C-Mod. The polarization response of the complex diagnostic is shown to be fully captured using a Fourier expansion of the detector signals in terms of even harmonics of the input polarization angle. The system's high precision robotic control of position and orientation allow it to be used also to calibrate the geometry of the instrument's view. Combined with careful measurements of the narrow bandpass spectral filters, this system fully calibrates the diagnostic without any plasma discharges. The system's high repeatability, flexibility, and speed has been exploited to quantify several systematics in the MSE diagnostic response, providing a more complete understanding of the diagnostic performance.

  10. Understanding of Neutral Gas Transport in the Alcator C-Mod Tokamak Divertor

    Energy Technology Data Exchange (ETDEWEB)

    D.P. Stotler; C.S. Pitcher; C.J. Boswell; B. LaBombard; J.L. Terry; J.D. Elder; S. Lisgo

    2002-05-07

    A series of experiments on the effect of divertor baffling on the Alcator C-Mod tokamak provides stringent tests on models of neutral gas transport in and around the divertor region. One attractive feature of these experiments is that a trial description of the background plasma can be constructed from experimental measurements using a simple model, allowing the neutral gas transport to be studied with a stand-alone code. The neutral-ion and neutral-neutral elastic scattering processes recently added to the DEGAS 2 Monte Carlo neutral transport code permit the neutral gas flow rates between the divertor and main chamber to be simulated more realistically than before. Nonetheless, the simulated neutral pressures are too low and the deuterium Balmer-alpha emission profiles differ qualitatively from those measured, indicating an incomplete understanding of the physical processes involved in the experiment. Some potential explanations are examined and opportunities for future exploration a re highlighted. Improvements to atomic and surface physics data and models will play a role in the latter.

  11. The multi-spectral line-polarization MSE system on Alcator C-Mod

    Science.gov (United States)

    Mumgaard, R. T.; Scott, S. D.; Khoury, M.

    2016-11-01

    A multi-spectral line-polarization motional Stark effect (MSE-MSLP) diagnostic has been developed for the Alcator C-Mod tokamak wherein the Stokes vector is measured in multiple wavelength bands simultaneously on the same sightline to enable better polarized background subtraction. A ten-sightline, four wavelength MSE-MSLP detector system was designed, constructed, and qualified. This system consists of a high-throughput polychromator for each sightline designed to provide large étendue and precise spectral filtering in a cost-effective manner. Each polychromator utilizes four narrow bandpass interference filters and four custom large diameter avalanche photodiode detectors. Two filters collect light to the red and blue of the MSE emission spectrum while the remaining two filters collect the beam pi and sigma emission generated at the same viewing volume. The filter wavelengths are temperature tuned using custom ovens in an automated manner. All system functions are remote controllable and the system can be easily retrofitted to existing single-wavelength line-polarization MSE systems.

  12. Understanding of Neutral Gas Transport in the Alcator C-Mod Tokamak Divertor

    International Nuclear Information System (INIS)

    A series of experiments on the effect of divertor baffling on the Alcator C-Mod tokamak provides stringent tests on models of neutral gas transport in and around the divertor region. One attractive feature of these experiments is that a trial description of the background plasma can be constructed from experimental measurements using a simple model, allowing the neutral gas transport to be studied with a stand-alone code. The neutral-ion and neutral-neutral elastic scattering processes recently added to the DEGAS 2 Monte Carlo neutral transport code permit the neutral gas flow rates between the divertor and main chamber to be simulated more realistically than before. Nonetheless, the simulated neutral pressures are too low and the deuterium Balmer-alpha emission profiles differ qualitatively from those measured, indicating an incomplete understanding of the physical processes involved in the experiment. Some potential explanations are examined and opportunities for future exploration a re highlighted. Improvements to atomic and surface physics data and models will play a role in the latter

  13. BOUT++ Simulations of Edge Turbulence in Alcator C-Mod's EDA H-Mode

    Science.gov (United States)

    Davis, E. M.; Porkolab, M.; Hughes, J. W.; Labombard, B.; Snyder, P. B.; Xu, X. Q.

    2013-10-01

    Energy confinement in tokamaks is believed to be strongly controlled by plasma transport in the pedestal. The pedestal of Alcator C-Mod's Enhanced Dα (EDA) H-mode (ν* > 1) is regulated by a quasi-coherent mode (QCM), an edge fluctuation believed to reduce particle confinement and allow steady-state H-mode operation. ELITE calculations indicate that EDA H-modes sit well below the ideal peeling-ballooning instability threshold, in contrast with ELMy H-modes. Here, we use a 3-field reduced MHD model in BOUT++ to study the effects of nonideal and nonlinear physics on EDA H-modes. In particular, incorporation of realistic pedestal resistivity is found to drive resistive ballooning modes (RBMs) and increase linear growth rates above the corresponding ideal rates. These RBMs may ultimately be responsible for constraining the EDA pedestal gradient. However, recent high-fidelity mirror Langmuir probe measurements indicate that the QCM is an electron drift-Alfvén wave - not a RBM. Inclusion of the parallel pressure gradient term in the 3-field reduced MHD Ohm's law and various higher field fluid models are implemented in an effort to capture this drift wave-like response. This work was performed under the auspices of the USDoE under awards DE-FG02-94-ER54235, DE-AC52-07NA27344, DE-AC52-07NA27344, and NNSA SSGF.

  14. Simulations of beam-emission spectroscopy on Alcator C-Mod (abstract)

    Energy Technology Data Exchange (ETDEWEB)

    Sampsell, M. B.; Bravenec, R. V.; Rowan, W. L.; Eisner, E. C.; Patterson, D. M.; Bretz, N. L.; Boivin, R. L.; Hubbard, A. E.; Irby, J. H.; Marmar, E. S. (and others)

    2001-01-01

    An eight-channel beam-emission-spectroscopy (BES)1 system has been installed on the Alcator C-Mod tokamak, intended for use with a diagnostic neutral hydrogen beam (DNB). Capable of localized measurements from the plasma edge to the plasma core, the BES diagnostic collects light from the first Balmer transition (H{sub {alpha}}) resultant from beam/plasma collisions. The H{sub {alpha}} line splits into several components whose central wavelengths depend on the viewing geometry, the magnetic field, and the beam energy. This is due to the Doppler shifts from viewing the beam off perpendicular, the different velocities of the three mass components of the beam (H, H{sub 2}, H{sub 3}), and the large motional Stark effect. Optimal signal-to-noise requires collecting these components while attenuating all other emission: primarily bremsstrahlung and D{sub {alpha}} radiation (from plasma D{sup 0}/e{sup -} collisions). Tunable bandpass filters are thus required. A BES simulation code has been developed that calculates the brightnesses (bremsstrahlung, D{sub {alpha}}, H{sub {alpha}}) versus wavelength using plasma profile data from the C-Mod MDSplus database,2 a computation of the beam penetration, the viewing and DNB geometries, and bandpass filter characteristics. The model was first used to estimate signal levels and choose the optimal BES bandpass filters; its ultimate purpose is to determine the shot-to-shot tuning requirements of the filters for different discharge conditions. Comparisons of measured and predicted background bremsstrahlung and D{sub {alpha}} brightnesses are presented, as are first measurements and calculations of the beam emission. The code is written in the IDL programming language3 utilizing the ''widget'' graphical user interface. Designed for geometrical and spectral flexibility, it can be modified to simulate other beam diagnostics such as motional-Stark-effect plasma current measurements and charge-exchange recombination

  15. Lithium pellet injection experiments on the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, D.T.

    1996-06-01

    A pellet enhanced performance mode, showing significantly reduced core transport, is regularly obtained after the injection of deeply penetrating lithium pellets into Alcator C-Mod discharges. These transient modes, which typically persist about two energy confinement times, are characterized by a steep pressure gradient ({ell}{sub p} {le} a/5) in the inner third of the plasma, indicating the presence of an internal transport barrier. Inside this barrier, particle and energy diffusivities are greatly reduced, with ion thermal diffusivity dropping to near neoclassical values. Meanwhile, the global energy confinement time shows a 30% improvement over ITER89-P L-mode scaling. The addition of ICRF auxiliary heating shortly after the pellet injection leads to high fusion reactivity with neutron rates enhanced by an order of magnitude over L-mode discharges with similar input powers. A diagnostic system for measuring equilibrium current density profiles of tokamak plasmas, employing high speed lithium pellets, is also presented. Because ions are confined to move along field lines, imaging the Li{sup +} emission from the toroidally extended pellet ablation cloud gives the direction of the magnetic field. To convert from temporal to radial measurements, the 3-D trajectory of the pellet is determined using a stereoscopic tracking system. These measurements, along with external magnetic measurements, are used to solve the Grad-Shafranov equation for the magnetic equilibrium of the plasma. This diagnostic is used to determine the current density profile of PEP modes by injection of a second pellet during the period of good confinement. This measurement indicates that a region of reversed magnetic shear exists at the plasma core. This current density profile is consistent with TRANSP calculations for the bootstrap current created by the pressure gradient. MHD stability analysis indicates that these plasmas are near the n = {infinity} and the n = 1 marginal stability limits.

  16. Survey of ICRF heating experiments and enhanced performance modes in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Y.; Boivin, R.L.; Bonoli, P.T. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center] [and others

    1996-12-01

    Results of ICRF heating experiments in Alcator C-Mod during the November 1994 to June 1995 campaign are summarized. Efficient heating of high-density (nbar{sub e} ``

  17. Electron heating via mode converted ion Bernstein waves in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bonoli, P.T.; OShea, P.; Brambilla, M.; Golovato, S.N.; Hubbard, A.E.; Porkolab, M.; Takase, Y.; Boivin, R.L.; Bombarda, F.; Christensen, C.; Fiore, C.L.; Garnier, D.; Goetz, J.; Granetz, R.; Greenwald, M.; Horne, S.F.; Hutchinson, I.H.; Irby, J.; Jablonski, D.; LaBombard, B.; Lipschultz, B.; Marmar, E.; May, M.; Mazurenko, A.; McCracken, G.; Nachtrieb, R.; Niemczewski, A.; Ohkawa, H.; Pappas, D.A.; Reardon, J.; Rice, J.; Rost, C.; Schachter, J.; Snipes, J.A.; Stek, P.; Takase, K.; Terry, J.; Wang, Y.; Watterson, R.L.; Welch, B.; Wolfe, S.M. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1997-05-01

    Highly localized direct electron heating [full width at half-maximum (FWHM){congruent}0.2a] via mode converted ion Bernstein waves has been observed in the Alcator C-Mod Tokamak [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)]. Electron heating at or near the plasma center (r/a{ge}0.3) has been observed in H({sup 3}He) discharges at B{sub 0}=(6.0{endash}6.5)T and n{sub e}(0){congruent}1.8{times}10{sup 20}m{sup {minus}3}. [Here, the minority ion species is indicated parenthetically.] Off-axis heating (r/a{ge}0.5) has also been observed in D({sup 3}He) plasmas at B{sub 0}=7.9T. The concentration of {sup 3}He in these experiments was in the range of n{sub 3{sub He}}/n{sub e}{congruent}(0.2{endash}0.3) and the locations of the mode conversion layer and electron heating peak could be controlled by changing the {sup 3}He concentration or toroidal magnetic field (B{sub 0}). The electron heating profiles were deduced using a rf modulation technique. Detailed comparisons with one-dimensional and toroidal full-wave models in the ion cyclotron range of frequencies have been carried out. One-dimensional full-wave code predictions were found to be in qualitative agreement with the experimental results. Toroidal full-wave calculations indicated the importance of volumetric and wave focusing effects in the interpretation of the experimental results. {copyright} {ital 1997 American Institute of Physics.}

  18. The design and performance of a twenty barrel hydrogen pellet injector for Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Urbahn, J.A.

    1994-05-01

    A twenty barrel hydrogen pellet injector has been designed, built and tested both in the laboratory and on the Alcator C-Mod Tokamak at MIT. The injector functions by firing pellets of frozen hydrogen or deuterium deep into the plasma discharge for the purpose of fueling the plasma, modifying the density profile and increasing the global energy confinement time. The design goals of the injector are: (1) Operational flexibility, (2) High reliability, (3) Remote operation with minimal maintenance. These requirements have lead to a single stage, pipe gun design with twenty barrels. Pellets are formed by in- situ condensation of the fuel gas, thus avoiding moving parts at cryogenic temperatures. The injector is the first to dispense with the need for cryogenic fluids and instead uses a closed cycle refrigerator to cool the thermal system components. The twenty barrels of the injector produce pellets of four different size groups and allow for a high degree of flexibility in fueling experiments. Operation of the injector is under PLC control allowing for remote operation, interlocked safety features and automated pellet manufacturing. The injector has been extrusively tested and shown to produce pellets reliably with velocities up to 1400 m/sec. During the period from September to November of 1993, the injector was successfully used to fire pellets into over fifty plasma discharges. Experimental results include data on the pellet penetration into the plasma using an advanced pellet tracking diagnostic with improved time and spatial response. Data from the tracker indicates pellet penetrations were between 30 and 86 percent of the plasma minor radius.

  19. Lithium pellet injection experiments on the Alcator C-Mod tokamak

    International Nuclear Information System (INIS)

    A pellet enhanced performance mode, showing significantly reduced core transport, is regularly obtained after the injection of deeply penetrating lithium pellets into Alcator C-Mod discharges. These transient modes, which typically persist about two energy confinement times, are characterized by a steep pressure gradient (ell p ≤ a/5) in the inner third of the plasma, indicating the presence of an internal transport barrier. Inside this barrier, particle and energy diffusivities are greatly reduced, with ion thermal diffusivity dropping to near neoclassical values. Meanwhile, the global energy confinement time shows a 30% improvement over ITER89-P L-mode scaling. The addition of ICRF auxiliary heating shortly after the pellet injection leads to high fusion reactivity with neutron rates enhanced by an order of magnitude over L-mode discharges with similar input powers. A diagnostic system for measuring equilibrium current density profiles of tokamak plasmas, employing high speed lithium pellets, is also presented. Because ions are confined to move along field lines, imaging the Li+ emission from the toroidally extended pellet ablation cloud gives the direction of the magnetic field. To convert from temporal to radial measurements, the 3-D trajectory of the pellet is determined using a stereoscopic tracking system. These measurements, along with external magnetic measurements, are used to solve the Grad-Shafranov equation for the magnetic equilibrium of the plasma. This diagnostic is used to determine the current density profile of PEP modes by injection of a second pellet during the period of good confinement. This measurement indicates that a region of reversed magnetic shear exists at the plasma core. This current density profile is consistent with TRANSP calculations for the bootstrap current created by the pressure gradient. MHD stability analysis indicates that these plasmas are near the n = ∞ and the n = 1 marginal stability limits

  20. Kinetic modeling of divertor heat load fluxes in the Alcator C-Mod and DIII-D tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Pankin, A. Y. [Tech-X Corporation, Boulder, Colorado 80303 (United States); Rafiq, T.; Kritz, A. H. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Park, G. Y. [National Fusion Research Institute, Daejeon, 305-333 (Korea, Republic of); Chang, C. S.; Ku, S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Brunner, D.; Hughes, J. W.; LaBombard, B.; Terry, J. L. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Groebner, R. J. [General Atomics, San Diego, California 92121 (United States)

    2015-09-15

    The guiding-center kinetic neoclassical transport code, XGC0 [Chang et al., Phys. Plasmas 11, 2649 (2004)], is used to compute the heat fluxes and the heat-load width in the outer divertor plates of Alcator C-Mod and DIII-D tokamaks. The dependence of the width of heat-load fluxes on neoclassical effects, neutral collisions, and anomalous transport is investigated using the XGC0 code. The XGC0 code includes realistic X-point geometry, a neutral source model, the effects of collisions, and a diffusion model for anomalous transport. It is observed that the width of the XGC0 neoclassical heat-load is approximately inversely proportional to the total plasma current I{sub p.} The scaling of the width of the divertor heat-load with plasma current is examined for an Alcator C-Mod discharge and four DIII-D discharges. The scaling of the divertor heat-load width with plasma current is found to be weaker in the Alcator C-Mod discharge compared to scaling found in the DIII-D discharges. The effect of neutral collisions on the 1/I{sub p} scaling of heat-load width is shown not to be significant. Although inclusion of poloidally uniform anomalous transport results in a deviation from the 1/I{sub p} scaling, the inclusion of the anomalous transport that is driven by ballooning-type instabilities results in recovering the neoclassical 1/I{sub p} scaling. The Bohm or gyro-Bohm scalings of anomalous transport do not strongly affect the dependence of the heat-load width on plasma current. The inclusion of anomalous transport, in general, results in widening the width of neoclassical divertor heat-load and enhances the neoclassical heat-load fluxes on the divertor plates. Understanding heat transport in the tokamak scrape-off layer plasmas is important for strengthening the basis for predicting divertor conditions in ITER.

  1. Disruption Mitigation Experiments with Two Gas Jets on Alcator C-Mod

    International Nuclear Information System (INIS)

    Full text: Massive gas injection (MGI) disruption mitigation experiments have shown that this technique can quickly convert a large fraction of plasma thermal and magnetic energy into radiated power. To date, gas has been injected from a single spatial location, and bolometric measurements have shown that the resulting radiated power is often toroidally asymmetric, which could cause melting of beryllium first wall surfaces in ITER. Therefore, the ITER MGI system proposes multiple gas jets distributed around the torus. On Alcator C-Mod, a 2nd gas jet has been installed 154 degrees around the torus from the existing gas jet. The hardware components of both gas jets are nominally identical. A pair of AXUV photodiode arrays viewing the plasma midplane is used to measure the n = 1 component of the toroidal asymmetry, and a toroidally-distributed set of six individual detectors, each viewing a collimated slice of the plasma, provides toroidal resolution higher than n = 1 and is used to calculate the toroidal peaking factor (TPF) of the radiated power. Experiments have begun to characterise the effect of using two jets on the radiation TPF, varying the relative timing between the firing of the gas jets from shot-to-shot. It is observed that the TPF depends on the phase of the disruption. During the pre-TQ, when the gas is cooling the plasma edge, the TPF varies reproducibly with the relative gas jet timing. However, during the thermal quench (TQ) and current quench (CQ), when most of the plasma energy is radiated, the results are more complicated. At large positive delay times (i.e., jet 2 fires well after jet 1) the TPF is seen to be variable and often high, agreeing with earlier results using only this jet. However, at large negative delay times (jet 2 fires well before jet 1), the TPF is significantly lower and more reproducible. This may indicate that slight differences in hardware and/or geometry between the two gas jet systems are important. The growth of n = 1 MHD

  2. Current Profile Measurements from Moderate to Strong Lower Hybrid Single-Pass Damping on Alcator C-Mod

    Science.gov (United States)

    Mumgaard, R. T.; Wallace, G. M.; Scott, S. D.; Shiraiwa, S.; Faust, I.; Parker, R. R.

    2015-11-01

    Lower Hybrid Current Drive (LHCD) is an effective tool to non-inductively drive up to 100% of the plasma current on Alcator C-Mod. Measurements with an upgraded MSE diagnostic show that the fast-electron current profile is broader than the Ohmic current profile but still located the plasma core in agreement with strongly centrally peaked fast electron bremsstrahlung (FEB) measurements. Scans in a regime of high current drive efficiency across a range of density, LHCD power, launched n||, and plasma current show the driven current profile, FEB profile shapes, and current drive efficiency are sensitive only to total plasma current. Simulations using ray-tracing Fokker Planck codes show that the rays make 1-3 bounces through the plasma edge to bridge the spectral gap. Although in agreement with the total current, the simulations qualitatively disagree with experiment regarding current and FEB profiles as well as sensitivity to power and density. Simulations at higher plasma temperature and current predict stronger single-pass damping and preliminary experiments show increased current drive efficiency. Experiments to determine if the profile discrepancies persist when the ray bounces play a reduced role are planned, including companion experiments in D and He resulting in different edge plasma conditions. This work was performed on the Alcator C-Mod tokamak, a DoE Office of Science user facility, and is supported by USDoE awards DE-FC02-99ER54512 and DE-AC02-09CH11466.

  3. EMC3-EIRENE modeling of toroidally-localized divertor gas injection experiments on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Lore, J.D., E-mail: lorejd@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Reinke, M.L. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); LaBombard, B. [Plasma Science and Fusion Center, MIT, Cambridge, MA 02139 (United States); Lipschultz, B. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Churchill, R.M. [Plasma Science and Fusion Center, MIT, Cambridge, MA 02139 (United States); Pitts, R.A. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Feng, Y. [Max Planck Institute for Plasma Physics, Greifswald (Germany)

    2015-08-15

    Experiments on Alcator C-Mod with toroidally and poloidally localized divertor nitrogen injection have been modeled using the three-dimensional edge transport code EMC3-EIRENE to elucidate the mechanisms driving measured toroidal asymmetries. In these experiments five toroidally distributed gas injectors in the private flux region were sequentially activated in separate discharges resulting in clear evidence of toroidal asymmetries in radiated power and nitrogen line emission as well as a ∼50% toroidal modulation in electron pressure at the divertor target. The pressure modulation is qualitatively reproduced by the modeling, with the simulation yielding a toroidal asymmetry in the heat flow to the outer strike point. Toroidal variation in impurity line emission is qualitatively matched in the scrape-off layer above the strike point, however kinetic corrections and cross-field drifts are likely required to quantitatively reproduce impurity behavior in the private flux region and electron temperatures and densities directly in front of the target.

  4. Pedestal Stability and Transport on the Alcator C-Mod Tokamak: Experiments in Support of Developing Predictive Capability

    International Nuclear Information System (INIS)

    Full text: New experimental data on the Alcator C-Mod tokamak are used to benchmark predictive modeling of the edge pedestal in various high-confinement regimes, contributing to a greater confidence in projection of pedestal height and width in ITER and reactors. Measurements in conventional Type-I ELMy H-mode have been used to test the theory of peeling-ballooning (PB) stability and pedestal structure predictions from the EPED model, which extends these theoretical comparisons to the highest pressure pedestals of any existing tokamak. Calculations with the ELITE code confirm that C-Mod ELMy H-modes operate near stability limits for ideal PB modes. Experimental C-Mod studies have provided supporting evidence for pedestal width scaling as the square root of poloidal beta at the pedestal top. This is the dependence that would be expected from theory if KBMs were responsible for limiting the pedestal width. The EPED model has been tested across an extended data on C-Mod, reproducing pedestal height and width reasonably well, and extending the tested range of EPED to within a factor of 3 of the absolute pedestal pressure targeted for ITER. In addition, C-Mod offers access to two regimes, enhanced D-alpha (EDA) H-mode and I- mode, that have high pedestals but in which large ELM activity is naturally suppressed and, instead, particle and impurity transport are regulated continuously. Significant progress has been made in both measuring and modeling pedestal fluctuations, transport and stability in these regimes. Pedestals of EDA H-mode and I-mode discharges are found to be ideal MHD stable, consistent with the general absence of ELM activity. Like ELITE, the BOUT++ code finds the EDA pedestal to be stable to ideal modes. However, it does identify finite growth rates for edge modes when realistic values of resistivity and diamagnetism are included. The result is consistent with the interpretation of the quasi-coherent mode (QCM), which is omnipresent in the EDA pedestal

  5. High resolution measurements of neutral density and ionization rate in the main chamber of the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R.L. E-mail: boivin@psfc.mit.edu; Goetz, J.; Hubbard, A.; Hughes, J.W.; Irby, J.; LaBombard, B.; Marmar, E.; Mossessian, D.; Terry, J.L

    2001-03-01

    Recent theoretical and experimental work has focused on the importance of neutrals in the edge dynamics of Alcator C-Mod plasmas. Two new high resolution detectors have been installed on the Alcator C-Mod tokamak to measure the neutral density and ionization rate near the edge of the discharge in the main chamber. The detectors consist of a 20 channel photodiode array which views the plasma tangentially 12.5 cm below the outer midplane, and 10 cm above the inner midplane, with a nominal radial resolution of 2 and 3 mm, respectively. The spectral bandwidth is limited by a filter with a very narrow band around the neutral deuterium Lyman alpha wavelength (1215 Angstrom). The local emissivity is then obtained via a standard Abel inversion of the absolutely calibrated brightness profile. Employing well-known branching ratios, and using measured local electron density and temperature, we therefore, infer the neutral density and ionization rate with similar radial resolution. We have observed that both Lyman alpha emissivity and ionization rate are usually peaked near the separatrix with a full width, half-maximum between 1 and 2 cm. The neutral density was found to drop rapidly with decreasing minor radius, from 2-3x10{sup 17}/m{sup 3} (5-10 mm outside the separatrix) to 1-2x10{sup 16}/m{sup 3} (5-10 mm inside the separatrix) for a line averaged density of 2.0x10{sup 20}/m{sup 3}. Variations in ionization rate and neutral density from low to high confinement mode (L and H mode) are also discussed.

  6. Measurements of relativistic emission from runaway electrons in Alcator C-Mod: spectrum, polarization, and spatial structure

    Science.gov (United States)

    Granetz, Robert; Mumgaard, Robert

    2014-10-01

    At low densities, runaway electrons (RE's) can be generated during the flattop of Alcator C-Mod discharges with highly relativistic energies, γ >> 1 , allowing careful study under steady conditions. These RE's emit light in a narrow forward-peaked cone which is detected with a number of diagnostics, including spectrometers, a video imaging camera, and polarimetry (using the MSE system), in addition to the standard hard x-ray detectors. These measurements of the relativistic emission can provide information about the RE energy distribution, pitch angle distribution, and spatial distribution. Unlike most other tokamaks, C-Mod's high magnetic field shifts the peak of the continuum emission into the visible, due to the smaller gyroradius and higher gyro-frequency, allowing for excellent spectral coverage with standard spectrometers, and thus detailed comparison to theoretical predictions of synchrotron and bremsstrahlung spectra. Additionally, camera images occasionally show highly structured formations. Profiles of the polarization fraction and polarization angle show radial structure, including a jump of 90° outboard of the magnetic axis, in qualitative agreement with recent theoretical calculations for relativistic electrons in a tokamak field. This work is supported by the U.S. Department of Energy.

  7. Pedestal structure and stability in H-mode and I-mode: a comparative study on Alcator C-Mod

    International Nuclear Information System (INIS)

    New experimental data from the Alcator C-Mod tokamak are used to benchmark predictive modelling of the edge pedestal in various high-confinement regimes, contributing to greater confidence in projection of pedestal height and width in ITER and reactors. ELMy H-modes operate near stability limits for ideal peeling–ballooning modes, as shown by calculations with the ELITE code. Experimental pedestal width in ELMy H-mode scales as the square root of βpol at the pedestal top, i.e. the dependence expected from theory if kinetic ballooning modes (KBMs) were responsible for limiting the pedestal width. A search for KBMs in experiment has revealed a short-wavelength electromagnetic fluctuation in the pedestal that is a candidate driver for inter-edge localized mode (ELM) pedestal regulation. A predictive pedestal model (EPED) has been tested on an extended set of ELMy H-modes from C-Mod, reproducing pedestal height and width reasonably well across the data set, and extending the tested range of EPED to the highest absolute pressures available on any existing tokamak and to within a factor of three of the pedestal pressure targeted for ITER. In addition, C-Mod offers access to two regimes, enhanced D-alpha (EDA) H-mode and I-mode, that have high pedestals, but in which large ELM activity is naturally suppressed and, instead, particle and impurity transport are regulated continuously. Pedestals of EDA H-mode and I-mode discharges are found to be ideal magnetohydrodynamic (MHD) stable with ELITE, consistent with the general absence of ELM activity. Invocation of alternative physics mechanisms may be required to make EPED-like predictions of pedestals in these kinds of intrinsically ELM-suppressed regimes, which would be very beneficial to operation in burning plasma devices. (paper)

  8. Study and optimization of boronization in Alcator C-Mod using the Surface Science Station (S{sup 3})

    Energy Technology Data Exchange (ETDEWEB)

    Ochoukov, Roman, E-mail: ochoukov@psfc.mit.edu [Plasma Science and Fusion Center MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Whyte, Dennis; Lipschultz, Bruce; LaBombard, Brian [Plasma Science and Fusion Center MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Gierse, Niels [Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, Juelich (Germany); Physikalisches Institut, Universitaet zu Koeln, D-50937 Cologne (Germany); Harrison, Soren [Fusion Research Technologies, 519 Somerville Avenue 243, Somerville, MA 02143 (United States)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Boron deposition profiles measured on Alcator C-Mod during boronization. Black-Right-Pointing-Pointer Boron deposition profile is consistent with ionic deposition. Black-Right-Pointing-Pointer Monte Carlo simulation of boron deposition agrees with experiment assuming warm ({approx}1-10 eV) boron{sup +1} ions. - Abstract: A Surface Science Station (S{sup 3}) on the Alcator C-Mod tokamak is used to study and optimize the location and rate of boron film deposition in situ during electron cyclotron (EC) discharge plasmas using 2.45 GHz radio-frequency (RF) heating and a mixture of helium and diborane (B{sub 2}D{sub 6}) gasses. The radial profile of boron deposition is measured with a pair of quartz microbalances (QMB) on S{sup 3}, the faces of which can be rotated 360 Degree-Sign including orientations parallel and perpendicular to the toroidal magnetic field B{sub T} {approx}0.1 T. The plasma electron density is measured with a Langmuir probe, also on S{sup 3} in the vicinity of the QMBs, and typical values are {approx}1 Multiplication-Sign 10{sup 16} m{sup -3}. A maximum boron deposition rate of 0.82 {mu}g/cm{sup 2}/min is obtained, which corresponds to 3.5 nm/min if the film density is that of solid boron. These deposition rates are sufficient for boron film applications between tokamak discharges. However the deposition does not peak at the EC resonance as previously assumed. Rather, deposition peaks near the upper hybrid (UH) resonance, {approx}5 cm outboard of the EC resonance. This has implications for RF absorption, with the RF waves being no longer damped on the electrons at the EC resonance. The previously inferred radial locations of critical erosion zones in Alcator C-Mod also need to be re-evaluated. The boron deposition profile versus major radius follows the ion flux/density profile, implying that the boron deposition is primarily ionic. The application of a vertical magnetic field (B{sub V} {approx}0.01 T) was

  9. Design and operation of a novel divertor cryopumping system in Alcator C-Mod

    Science.gov (United States)

    Labombard, B.; Beck, B.; Bosco, J.; Childs, R.; Gwinn, D.; Irby, J.; Leccacorvi, R.; Marazita, S.; Mucic, N.; Pierson, S.; Rokhman, Y.; Titus, P.; Vieira, R.; Zaks, J.; Zhukovsky, A.

    2007-11-01

    C-Mod's recently installed upper-divertor cryopump is unique among the world's tokamaks, employing an array of gas-pumping slots that penetrate the upper divertor target. This geometry enables the use of a single toroidal loop of liquid helium, operating in an efficient heat transfer regime with low or no helium flow. A system pumping speed of 9,600 l/sec for D2 gas has been achieved, matching that of a full-scale prototype system. Neutral pressures in the pumping slots during upper-null plasmas (USN) are found to meet or exceed pressures in the lower divertor's private flux region during lower-null (LSN) -- evidence that the pumping-slot geometry is performing as intended. Very high steady-state pumping throughputs (exceeding ˜140 torr-l/s) have been demonstrated in USN. Reliable and efficient operation of the pump has been established, synchronized with the C-Mod shot cycle and consuming 60 to 90 liters of liquid helium during a full day of operation.

  10. In-situ erosion and deposition measurements of plasma-facing surfaces in Alcator C-Mod

    Science.gov (United States)

    Barnard, Harold S.

    2014-10-01

    The Accelerator Based In-situ Materials Surveillance (AIMS) diagnostic was recently developed to demonstrate the novel application of ion beam analysis (IBA) to in-vessel studies of plasma materials interactions in Alcator C-Mod. The AIMS diagnostic injects a 900 keV deuterium ion beam into the tokamak's vacuum vessel between plasma discharges while magnetic fields are used to steer the ion beam to plasma facing component (PFC) surfaces. Spectroscopic analysis of neutrons and gamma rays from the induced nuclear reactions provides a quantitative, spatially resolved map of the PFC surface composition that includes boron (B) and deuterium (D) content. Since AIMS is sensitive to low-Z elements and C-Mod regularly boronizes PFCs, the evolution of B and D on PFCs can be used to directly study erosion, deposition, and fuel retention in response to plasma operations and wall conditioning processes. AIMS analysis of 18 lower single null I-mode discharges show a net boron deposition rate of 6 +/- 2 nm/s on the inner wall while subsequent inner wall limited discharges and a disruption did not show significant changes in B. Measurements of D content showed relative changes of >2.5 following a similar trend. This suggests high D retention rates and net B deposition rates of ~18 cm/year of plasma exposure are possible and depend strongly on the plasma conditions. Ex-situ IBA was also performed on the same PFCs after removal from C-Mod, successfully validating the AIMS technique. These IBA measurements also show that the B content on the inner wall varied toroidally and poloidally from 0 to 3000 nm, demonstrating the importance of the spatial resolution provided by AIMS and the sensitivity of PFCs to B-field alignment. AIMS upgrades are underway for operation in 2014 and we anticipate new measurements correlating the evolution of PFC surfaces to plasma configuration, RF heating, and current drive scenarios. This work is supported by U.S. DOE Grant No. DE-FG02-94ER54235 and

  11. DIVIMP modeling of impurity flows and screening in Alcator C-Mod

    International Nuclear Information System (INIS)

    We report on impurity transport modeling using the DIVIMP code which is able to qualitatively reproduce the poloidal variation of non-recycling impurity penetration factor (PFNR) found in C-Mod experiments: a lower PFNR is computed at the inboard (3.6%) and divertor target locations (0.7%) than at the outboard (11%). By artificially increasing the modeled inner SOL plasma flow to correspond to measured values, a better quantitative agreement between modeled and measured PFs is achieved. We have also roughly reproduced the observed penetration factor for recycling impurities both in time dependence and magnitude. The model has shown that under attached conditions, the majority of recycling impurity ions flow into the confined plasma through the outboard side separatrix. For detached conditions the impurity influx across the separatrix is more concentrated near the divertor

  12. Upgraded PMI diagnostic capabilities using Accelerator-based In-situ Materials Surveillance (AIMS) on Alcator C-Mod

    Science.gov (United States)

    Kesler, Leigh; Barnard, Harold; Hartwig, Zachary; Sorbom, Brandon; Lanza, Richard; Terry, David; Vieira, Rui; Whyte, Dennis

    2014-10-01

    The AIMS diagnostic was developed to rapidly and non-invasively characterize in-situ plasma material interactions (PMI) in a tokamak. Recent improvements are described which significantly expand this measurement capability on Alcator C-Mod. The detection time at each wall location is reduced from about 10 min to 30 s, via improved hardware and detection geometry. Detectors are in an augmented re-entrant tube to maximize the solid angle between detectors and diagnostic locations. Spatial range is expanded by using beam dynamics simulation to design upgraded B-field power supplies to provide maximal poloidal access, including a ~20° toroidal range in the divertor. Measurement accuracy is improved with angular and energy resolved cross section measurements obtained using a separate 0.9 MeV deuteron ion accelerator. Future improvements include the installation of recessed scintillator tiles as beam targets for calibration of the diagnostic. Additionally, implanted depth marker tiles will enable AIMS to observe the in-situ erosion and deposition of high-Z plasma-facing materials. This work is supported by U.S. DOE Grant No. DE-FG02-94ER54235 and Cooperative Agreement No. DE-FC02-99ER54512.

  13. Lower Hybrid Wave Induced SOL Emissivity Variation at High Density on the Alcator C-Mod Tokamak

    International Nuclear Information System (INIS)

    Lower Hybrid Current Drive (LHCD) in the Alcator C-Mod tokamak provides current profile control for the generation of Advanced Tokamak (AT) plasmas. Non-thermal electron bremsstrahlung emission decreases dramatically at n-bare>1·1020[m-3] for diverted discharges, indicating low current drive efficiency. It is suggested that Scrape-Off-Layer (SOL) collisional absorption of LH waves is the cause for the absence of non-thermal electrons at high density. VUV and visible spectroscopy in the SOL provide direct information on collision excitation processes. Deuterium Balmer-, Lyman- and He-I transition emission measurements were used for initial characterization of SOL electron-neutral collisional absorption. Data from Helium and Deuterium LHCD discharges were characterized by an overall increase in the emissivity as well as an outward radial shift in the emissivity profile with increasing plasma density and applied LHCD power. High-temperature, high-field (Te = 5keV,Bt = 8T) helium discharges at high density display increased non-thermal signatures as well as reduced SOL emissivity. Variations in emissivity due to LHCD were seen in SOL regions not magnetically connected to the LH Launcher, indicating global SOL effects due to LHCD.

  14. ICRF Impurity Behavior with Boron Coated Molybdenum Tiles in Alcator C-Mod

    International Nuclear Information System (INIS)

    Full text: Although ion cyclotron range of frequency (ICRF) heating is considered an excellent candidate for bulk heating, minimizing impurity production associated with ICRF operation, particularly with metallic plasma facing components (PFC), remains one of the primary challenges for ICRF utilization. In C-Mod and present experiments, boronization, an in-situ applied boron film, is utilized to control impurities and its effectiveness has a limited lifetime. In C-Mod, the lifetime has been observed to be proportional to integrated injected RF Joules and the degradation is faster than in equivalent ohmic heated discharges the ICRF is enhancing the erosion rate of the boron film. In an effort to identify important erosion and impurity source locations, we have vacuum plasma sprayed ∼ 100 microns of boron on molybdenum tiles from the outer divertor shelf, main plasma limiters, and the RF antennas. We have also modified the shape of the main plasma limiter and increased our spectroscopic monitoring diagnostics of the main plasma limiter. Finally, we have installed a set of probes to monitor the plasma potential and RF fields on field lines connected an antenna. For ICRF heated H-modes, the core molybdenum levels was significantly reduced and remained at low levels for increased integrated injected RF Joules. The core molybdenum levels also no longer scales with RF power in L-mode in contrast with previous results with boronization and molybdenum plasma facing components. Initial Post campaign analysis of the boron coating will also be presented. Boronization and impurity, typically nitrogen or neon, seeded discharges enabled high plasma and ICRF antenna performance. The boronization suggests that other impurity sources are important but are yet to be identified. Impurity seeding had two important effects: reduced core molybdenum levels and suppressed antenna faults due to arcs and injections from antenna structure. The lower core molybdenum level is surprising since

  15. H-mode edge stability of Alcator C-mod plasmas

    International Nuclear Information System (INIS)

    For steady state H-mode operation, a relaxation mechanism is required to limit build-up of the edge gradient and impurity content. C-Mod sees two such mechanisms - EDA and grassy ELMs, but not large type I ELMs. In EDA the edge relaxation is provided by an edge localized quasi coherent electromagnetic mode that exists at moderate pedestal temperature T3.5 and does not limit the build up of the edge pressure gradient. The mode is not observed in the ideal MHD stability analysis, but is recorded in the nonlinear real geometry fluctuations modeling based on fluid equations and is thus tentatively identified as a resistive ballooning mode. At high edge pressure gradients and temperatures the mode is replaced by broadband fluctuations (f< 50 kHz) and small irregular ELMs are observed. Based on ideal MHD calculations that include the effects of edge bootstrap current, these ELMs are identified as medium n (10 < n < 50) coupled peeling/ballooning modes. The stability thresholds, its dependence on the plasma shape and the modes structure are studied experimentally and with the linear MHD stability code ELITE. (author)

  16. Impurity Screening in Ohmic and H-Mode Plasmas in the Alcator C-Mod Tokamak^*

    Science.gov (United States)

    McCracken, G. M.

    1996-11-01

    The impurity density in the confined plasma is determined not only by the impurity production rate but also by screening, i.e. the balance between the perpendicular and parallel transport in the SOL. The relative importance of screening has been studied by injecting gaseous recycling (Ne, Ar) and non-recycling impurities (N, C) into various poloidal positions of the SOL and divertor in C-Mod. The density of the non-recycling impurities in the core is a function of the poloidal position of injection, while the screening of recycling impurities is not. In both cases screening is significantly worse ( ~3x) during divertor detachment. For a given injection rate of N2 gas into H-mode discharges, the number of impurities in the core is typically a factor of 3 greater than for ohmic discharges. Optical imaging of low charge states of the injected non-recycling impurities using a camera and spectral filters shows a directed plume, indicating flow of impurities towards the divertor target at all positions studied, even at the inboard midplane. This implies that the friction force due to plasma flow dominates the parallel ion temperature gradient force. The spatial distribution of low charge states in the divertor has been studied using a multichord visible spectrometer, and the distribution of the nitrogen radiation has been been studied using a 20 chord bolometer array. The results show that for attached discharges the nitrogen radiation is predominantly in the SOL below the X-point. The position of the radiation is not strongly dependent on the position of nitrogen injection. The screening has been compared with calculations using the DIVIMP Monte Carlo code [1] and with an analytical model of the impurity transport. Work supported by U.S. DOE Contract No. DE-AC02-78ET51013. În collaboration with B Lipschultz, B LaBombard, J A Goetz, R Granetz, D Jablonski, H Ohkawa, J Terry, MIT, S Lisgo, P C Stangeby, University of Toronto, ^1P.C. Stangeby and D. Elder, J. Nucl. Mater

  17. Local gas injection as a scrape-off layer diagnostic on the Alcator C-Mod tokamak

    International Nuclear Information System (INIS)

    A capillary puffing array has been installed on Alcator C-Mod which allows localized introduction of gaseous species in the scrape-off layer. This system has been utilized in experiments to elucidate both global and local properties of edge transport. Deuterium fueling and recycling impurity screening are observed to be characterized by non-dimensional screening efficiencies which are independent of the location of introduction. In contrast, the behavior of non-recycling impurities is seen to be characterized by a screening time which is dependent on puff location. The work of this thesis has focused on the use of the capillary array with a camera system which can view impurity line emission plumes formed in the region of an injection location. The ionic plumes observed extend along the magnetic field line with a comet-like asymmetry, indicative of background plasma ion flow. The flow is observed to be towards the nearest strike-point, independent of x-point location, magnetic field direction, and other plasma parameters. While the axes of the plumes are generally along the field line, deviations are seen which indicate cross-field ion drifts. A quasi-two dimensional fluid model has been constructed to use the plume shapes of the first charge state impurity ions to extract information about the local background plasma, specifically the temperature, parallel flow velocity, and radial electric field. Through comparisons of model results with those of a three dimensional Monte Carlo code, and comparisons of plume extracted parameters with scanning probe measurements, the efficacy of the model is demonstrated. Plume analysis not only leads to understandings of local edge impurity transport, but also presents a novel diagnostic technique

  18. Local gas injection as a scrape-off layer diagnostic on the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Jablonski, D.F.

    1996-05-01

    A capillary puffing array has been installed on Alcator C-Mod which allows localized introduction of gaseous species in the scrape-off layer. This system has been utilized in experiments to elucidate both global and local properties of edge transport. Deuterium fueling and recycling impurity screening are observed to be characterized by non-dimensional screening efficiencies which are independent of the location of introduction. In contrast, the behavior of non-recycling impurities is seen to be characterized by a screening time which is dependent on puff location. The work of this thesis has focused on the use of the capillary array with a camera system which can view impurity line emission plumes formed in the region of an injection location. The ionic plumes observed extend along the magnetic field line with a comet-like asymmetry, indicative of background plasma ion flow. The flow is observed to be towards the nearest strike-point, independent of x-point location, magnetic field direction, and other plasma parameters. While the axes of the plumes are generally along the field line, deviations are seen which indicate cross-field ion drifts. A quasi-two dimensional fluid model has been constructed to use the plume shapes of the first charge state impurity ions to extract information about the local background plasma, specifically the temperature, parallel flow velocity, and radial electric field. Through comparisons of model results with those of a three dimensional Monte Carlo code, and comparisons of plume extracted parameters with scanning probe measurements, the efficacy of the model is demonstrated. Plume analysis not only leads to understandings of local edge impurity transport, but also presents a novel diagnostic technique.

  19. A Spatially Resolving X-ray Crystal Spectrometer for Measurement of Ion-temperature and Rotation-velocity Profiles on the AlcatorC-Mod Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K. W.; Bitter, M. L.; Scott, S. D.; Ince-Cushman, A.; Reinke, M.; Rice, J. E.; Beiersdorfer, P.; Gu, M. F.; Lee, S. G.; Broennimann, C. H.; Eikenberry, E. F.

    2009-03-24

    A new spatially resolving x-ray crystal spectrometer capable of measuring continuous spatial profiles of high resolution spectra (λ/dλ > 6000) of He-like and H-like Ar Kα lines with good spatial (~1 cm) and temporal (~10 ms) resolutions has been installed on the Alcator C-Mod tokamak. Two spherically bent crystals image the spectra onto four two-dimensional Pilatus II pixel detectors. Tomographic inversion enables inference of local line emissivity, ion temperature (Ti), and toroidal plasma rotation velocity (vφ) from the line Doppler widths and shifts. The data analysis techniqu

  20. Feedback system for divertor impurity seeding based on real-time measurements of surface heat flux in the Alcator C-Mod tokamak

    Science.gov (United States)

    Brunner, D.; Burke, W.; Kuang, A. Q.; LaBombard, B.; Lipschultz, B.; Wolfe, S.

    2016-02-01

    Mitigation of the intense heat flux to the divertor is one of the outstanding problems in fusion energy. One technique that has shown promise is impurity seeding, i.e., the injection of low-Z gaseous impurities (typically N2 or Ne) to radiate and dissipate the power before it arrives to the divertor target plate. To this end, the Alcator C-Mod team has created a first-of-its-kind feedback system to control the injection of seed gas based on real-time surface heat flux measurements. Surface thermocouples provide real-time measurements of the surface temperature response to the plasma heat flux. The surface temperature measurements are inputted into an analog computer that "solves" the 1-D heat transport equation to deliver accurate, real-time signals of the surface heat flux. The surface heat flux signals are sent to the C-Mod digital plasma control system, which uses a proportional-integral-derivative (PID) algorithm to control the duty cycle demand to a pulse width modulated piezo valve, which in turn controls the injection of gas into the private flux region of the C-Mod divertor. This paper presents the design and implementation of this new feedback system as well as initial results using it to control divertor heat flux.

  1. Feedback system for divertor impurity seeding based on real-time measurements of surface heat flux in the Alcator C-Mod tokamak.

    Science.gov (United States)

    Brunner, D; Burke, W; Kuang, A Q; LaBombard, B; Lipschultz, B; Wolfe, S

    2016-02-01

    Mitigation of the intense heat flux to the divertor is one of the outstanding problems in fusion energy. One technique that has shown promise is impurity seeding, i.e., the injection of low-Z gaseous impurities (typically N2 or Ne) to radiate and dissipate the power before it arrives to the divertor target plate. To this end, the Alcator C-Mod team has created a first-of-its-kind feedback system to control the injection of seed gas based on real-time surface heat flux measurements. Surface thermocouples provide real-time measurements of the surface temperature response to the plasma heat flux. The surface temperature measurements are inputted into an analog computer that "solves" the 1-D heat transport equation to deliver accurate, real-time signals of the surface heat flux. The surface heat flux signals are sent to the C-Mod digital plasma control system, which uses a proportional-integral-derivative (PID) algorithm to control the duty cycle demand to a pulse width modulated piezo valve, which in turn controls the injection of gas into the private flux region of the C-Mod divertor. This paper presents the design and implementation of this new feedback system as well as initial results using it to control divertor heat flux.

  2. Reduced-model (SOLT) simulations of an EDA H-mode shot at Alcator C-Mod

    Science.gov (United States)

    Russell, D. A.; D'Ippolito, D. A.; Myra, J. R.; Labombard, B.; Terry, J. L.; Zweben, S. J.

    2011-10-01

    Reduced-model scrape-off layer turbulence (SOLT) simulations of an Enhanced D-Alpha (EDA) H-mode observed at C-Mod were conducted to explore observed variations in scrape-off-layer (SOL) width. The amplitude of a mean poloidal flow was varied to control the level of turbulence in the simulation and to reproduce the observed heat flux across the separatrix. SOL width decreased with increasing input power and with increasing separatrix temperature in both experiment and simulation, consistent with the strong temperature dependence of collision-limited parallel heat flux. A persistent quasi-coherent mode (QCM) dominates the SOLT turbulence. The wavelength of the SOLT QCM is comparable to that of the QCM consistently observed on C-Mod during EDA operation. The SOLT QCM consists of a quasi-stationary string of vortices, located just inside the separatrix, poloidally convected by the mean flow and occasionally emitting blobs into the SOL. The mode frequency is dominated by the Doppler shift of this convected pattern. Analysis reveals underlying drift-interchange and Kelvin-Helmholtz instabilities. Supported by USDOE under DE-FG02-97ER54392, DE-AC02-09CH11466, DE-FC02-99ER54512 and S009625-F.

  3. Heat-flux footprints for I-mode and EDA H-mode plasmas on Alcator C-Mod

    Science.gov (United States)

    Terry, J. L.; LaBombard, B.; Brunner, D.; Hughes, J. W.; Reinke, M. L.; Whyte, D. G.

    2013-07-01

    IR thermography is used to measure the heat flux footprints on C-Mod's outer target in I-mode and EDA H-mode plasmas. The footprint profiles are fit to a function with a simple physical interpretation. The fit parameter that is sensitive to the power decay length into the SOL, λSOL, is ˜1-3× larger in I-modes than in H-modes at similar plasma current, which is the dominant dependence for the H-mode λSOL. In contrast, the fit parameter sensitive to transport into the private-flux-zone along the divertor leg is somewhat smaller in I-mode than in H-mode, but otherwise displays no obvious dependence on Ip, Bt, or stored energy. A third measure of the footprint width, the "integral width", is not significantly different between H- and I-modes. Also discussed are significant differences in the global power flows of the H-modes with "favorable"∇B drift direction and those of the I-modes with "unfavorable"∇B drift direction.

  4. Wide-frequency range, dynamic matching network and power system for the “Shoelace” radio frequency antenna on the Alcator C-Mod tokamak

    International Nuclear Information System (INIS)

    A wide-frequency range (50–300 kHz) power system has been implemented for use with a new RF antenna – the “Shoelace” antenna – built to drive coherent plasma fluctuations in the edge of the Alcator C-Mod tokamak. A custom, dynamically tunable matching network allows two commercial 1 kW, 50-Ω RF amplifiers to drive the low-impedance, inductive load presented by the antenna. This is accomplished by a discretely variable L-match network, with 81 independently selected steps available for each of the series and parallel legs of the matching configuration. A compact programmable logic device provides a control system that measures the frequency with better than 1 kHz accuracy and transitions to the correct tuning state in less than 1 ms. At least 85% of source power is dissipated in the antenna across the operational frequency range, with a minimum frequency slew rate of 1 MHz/s; the best performance is achieved in the narrower band from 80 to 150 kHz which is of interest in typical experiments. The RF frequency can be run with open-loop control, following a pre-programmed analog waveform, or phase-locked to track a plasma fluctuation diagnostic signal in real time with programmable phase delay; the amplitude control is always open-loop. The control waveforms and phase delay are programmed remotely. These tools have enabled first-of-a-kind measurements of the tokamak edge plasma system response in the frequency range and at the wave number at which coherent fluctuations regulate heat and particle transport through the plasma boundary

  5. Wide-frequency range, dynamic matching network and power system for the "Shoelace" radio frequency antenna on the Alcator C-Mod tokamak.

    Science.gov (United States)

    Golfinopoulos, Theodore; LaBombard, Brian; Burke, William; Parker, Ronald R; Parkin, William; Woskov, Paul

    2014-04-01

    A wide-frequency range (50-300 kHz) power system has been implemented for use with a new RF antenna - the "Shoelace" antenna - built to drive coherent plasma fluctuations in the edge of the Alcator C-Mod tokamak. A custom, dynamically tunable matching network allows two commercial 1 kW, 50-Ω RF amplifiers to drive the low-impedance, inductive load presented by the antenna. This is accomplished by a discretely variable L-match network, with 81 independently selected steps available for each of the series and parallel legs of the matching configuration. A compact programmable logic device provides a control system that measures the frequency with better than 1 kHz accuracy and transitions to the correct tuning state in less than 1 ms. At least 85% of source power is dissipated in the antenna across the operational frequency range, with a minimum frequency slew rate of 1 MHz/s; the best performance is achieved in the narrower band from 80 to 150 kHz which is of interest in typical experiments. The RF frequency can be run with open-loop control, following a pre-programmed analog waveform, or phase-locked to track a plasma fluctuation diagnostic signal in real time with programmable phase delay; the amplitude control is always open-loop. The control waveforms and phase delay are programmed remotely. These tools have enabled first-of-a-kind measurements of the tokamak edge plasma system response in the frequency range and at the wave number at which coherent fluctuations regulate heat and particle transport through the plasma boundary.

  6. Impurity screening studies in the ALCATOR C-Mod tokamak

    International Nuclear Information System (INIS)

    Screening experiments have been undertaken in both limited and diverted discharges with a range of gaseous impurities in ohmic discharges. Measurements have been made as a function of plasma density and of the poloidal position of gas injection. It has been found that for recycling impurities such as neon and argon the number of impurities in the core plasma is proportional to the number injected. For non-recycling impurities (carbon and nitrogen) the number in the core is a function of the rate of injection. For discharges limited on the inner wall the screening is a function of the poloidal position of injection, with the injection at the inner wall giving the poorest screening. In diverted discharges with recycling impurities the position of injection does not significantly affect the screening. For non-recycling impurities the screening is typically a factor of 3 better when impurities are injected from the divertor rather than from the outside midplane. However, the best screening occurs when the impurities are injected at the inner midplane. Screening is typically a factor of 10 better for diverted than for limited discharges. Impurity transport has been modelled using the Monte Carlo code DIVIMP with a background plasma derived from experimental measurements of plasma parameters at the target and in the scrape-off layer (SOL). It is found that the code can reproduce the experimental measurements within a factor of 2. (author). 12 refs, 3 figs

  7. Molybdenum density profiles on C-Mod using FAC generated cooling curves

    Science.gov (United States)

    Reinke, M.

    2005-10-01

    For tokamaks with high-Z plasma facing components, maintaining a low impurity content is necessary to produce high quality, repeatable discharges. A GENeral Impurity Emissivity (GENIE) method is outlined for determining impurity profiles using experimental spectroscopy data, an impurity transport code, and the atomic physics package, Flexible Atomic Code (FAC). Modular programming is emphasized in order to make the method extendable to arbitrary impurities, diagnostic sets and tokamaks. Development of GENIE is ongoing, but a necessary first step is to verify FAC. A testing stage of GENIE that ignores transport is demonstrated and the results are validated against the published molybdenum cooling-curve generated using HULLAC. Bolometry and Thomson scattering data are used to determine molybdenum density profiles on Alcator C-Mod using the Mo cooling-curve. Instances where this method fails are shown as well to illustrate the need for a more advanced version of GENIE that generates and uses charge state distributions that assume transport.

  8. Divertor IR thermography on Alcator C-Moda)

    Science.gov (United States)

    Terry, J. L.; LaBombard, B.; Brunner, D.; Payne, J.; Wurden, G. A.

    2010-10-01

    Alcator C-Mod is a particularly challenging environment for thermography. It presents issues that will similarly face ITER, including low-emissivity metal targets, low-Z surface films, and closed divertor geometry. In order to make measurements of the incident divertor heat flux using IR thermography, the C-Mod divertor has been modified and instrumented. A 6° toroidal sector has been given a 2° toroidal ramp in order to eliminate magnetic field-line shadowing by imperfectly aligned divertor tiles. This sector is viewed from above by a toroidally displaced IR camera and is instrumented with thermocouples and calorimeters. The camera provides time histories of surface temperatures that are used to compute incident heat-flux profiles. The camera sensitivity is calibrated in situ using the embedded thermocouples, thus correcting for changes and nonuniformities in surface emissivity due to surface coatings.

  9. Direct detection of lower hybrid wave using a reflectometer on Alcator C-Moda)

    Science.gov (United States)

    Shiraiwa, S.; Baek, S.; Dominguez, A.; Marmar, E.; Parker, R.; Kramer, G. J.

    2010-10-01

    The possibility of directly detecting a density perturbation produced by lower hybrid (LH) waves using a reflectometer is presented. We investigate the microwave scattering of reflectometer probe beams by a model density fluctuation produced by short wavelength LH waves in an Alcator C-Mod experimental condition. In the O-mode case, the maximum response of phase measurement is found to occur when the density perturbation is approximately centimeters in front of the antenna, where Bragg scattering condition is satisfied. In the X-mode case, the phase measurement is predicted to be more sensitive to the density fluctuation close to the cut-off layer. A feasibility test was carried out using a 50 GHz O-mode reflectometer on the Alcator C-Mod tokamak, and positive results including the detection of 4.6 GHz pump wave and parametric decay instabilities were obtained.

  10. Evaluation of Optimized ICRF and LHRF Antennas in Alcator C-Mod

    International Nuclear Information System (INIS)

    Full text: Ion cyclotron range of frequency heating (ICRF) and lower hybrid range of frequency current drive (LHCD) are expected to be key heating and current drive actuators for future fusion reactors and devices. However, impurity contamination associated with ICRF antenna operation remains a major challenge, particularly in devices with metallic plasma facing components. For LHCD, maximizing coupled power to the plasma remains a challenge, particularly to maintain low reflection coefficient over range of plasma conditions. Here, we report on an experimental investigation to test whether a field aligned (FA) ICRF antenna can reduce the impurity contamination and SOL modification associated with antenna operation. We also report on results from a new limiter for the LH coupler designed to reduce reflection coefficients across a wider range of plasma conditions. The unique feature of the so-called FA-antenna is that the current straps and antenna box structure are perpendicular to the total magnetic field. This alignment allows integrated E|| (electric field along a magnetic field line) to be minimized through symmetry. Using finite element method and a cold plasma model, the FA-antenna has been found to have lower integrated E|| relative to the previous antenna geometry. Initial results indicate that the impurity contamination associated with the FA-antenna is lower relative to our standard ICRF antennas. Configured as a 2-strap antenna, the antenna has lower core impurity contamination and lower impurity source at the antenna at high power density (∼ 15 MW/m2). An array of core and boundary plasma diagnostics are presently being used to characterize the impurity behavior and impact on the SOL transport and SOL density profiles; the latest results will be presented. For LHCD, reflection coefficients are very sensitive to the local density and its profile in front of the LHCD coupler. Previously the local LH coupler protection limiter was fixed to the outer wall of the vacuum vessel. The new limiter is mounted on the coupler and protrudes 0.25 mm beyond the coupler for plasma heat flux protection. The protection tiles allow the LH launcher to be moved closer to the plasma than previously possible. Initial high power (Pnet ∼ 700 kW) results show lower reflection coefficients were achieved (Γ2 ∼ 0.1) as compared to the old configuration (Γ2 ∼ 0.2). (author)

  11. Investigation of the origin of neutrals in the main chamber of Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Lipschultz, B. [Massachusetts Institute of Technology Plasma Science and Fusion Center Cambridge, MA (United States)]. E-mail: Blip@psfc.mit.edu; LaBombard, B. [Massachusetts Institute of Technology Plasma Science and Fusion Center Cambridge, MA (United States); Pitcher, C.S. [Plasma Surface Engineering Inc, Toronto (Canada); Boivin, R

    2002-06-01

    A series of experiments are described which are aimed at quantifying the relative contribution of divertor leakage and radial ion transport on neutral pressures surrounding the core plasma. Evidence is presented implying that cross-field transport competes with, or dominates, parallel transport in such a way that plasma exists far out in the scrape-off layer (SOL) in the shadow of limiters and recycles on main chamber surfaces. The transition from L- to H-mode core confinement does not affect the far SOL characteristics nor the scaling of pressures around the plasma. Variations in magnetic equilibrium are used to vary the divertor pressures independent of the core plasma. Based on the analysis of such experiments using a simple neutral flow model we estimate that neutrals escaping from leaks in the lower (closed) divertor during lower x-point operation contribute a smaller fraction ({approx}10-30%) of the midplane pressure than main chamber recycling. The inferred leakage is much larger from the upper (open) divertor during upper x-point operation. Most neutrals escaping from either divertor do not directly travel to the midplane. Instead, they are redirected, most likely by some combination of ionization and/or collisions (elastic, charge exchange). (author)

  12. Radiofrequency-heated enhanced confinement modes in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Y.; Boivin, R.L.; Bombarda, F.; Bonoli, P.T.; Christensen, C.; Fiore, C.; Garnier, D.; Goetz, J.A.; Golovato, S.N.; Granetz, R.; Greenwald, M.; Horne, S.F.; Hubbard, A.; Hutchinson, I.H.; Irby, J.; LaBombard, B.; Lipschultz, B.; Marmar, E.; May, M.; Mazurenko, A.; McCracken, G.; OShea, P.; Porkolab, M.; Reardon, J.; Rice, J.; Rost, C.; Schachter, J.; Snipes, J.A.; Stek, P.; Terry, J.; Watterson, R.; Welch, B.; Wolfe, S. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1997-05-01

    Enhanced confinement modes up to a toroidal field of B{sub T}=8T have been studied with up to 3.5 MW of radiofrequency (rf) heating power in the ion cyclotron range of frequencies (ICRF) at 80 MHz. H-mode is observed when the edge temperature exceeds a threshold value. The high confinement mode (H-mode) with higher confinement enhancement factors (H) and longer duration became possible after boronization by reducing the radiated power from the main plasma. A quasi-steady state with high confinement (H=2.0), high normalized beta ({beta}{sub N}=1.5), low radiated power fraction (P{sub rad}{sup main}/P{sub loss}=0.3), and low effective charge (Z{sub eff}=1.5) has been obtained in Enhanced D{sub {alpha}} H-mode. This type of H-mode has enhanced levels of continuous D{sub {alpha}} emission and very little or no edge localized mode (ELM) activity, and reduced core particle confinement time relative to ELM-free H-mode. The pellet enhanced performance (PEP) mode is obtained by combining core fueling with pellet injection and core heating. A highly peaked pressure profile with a central value of 8 atmospheres was observed. The steep pressure gradient drives off-axis bootstrap current, resulting in a shear reversed safety factor (q) profile. Suppression of sawteeth appears to be important in maintaining the highly peaked pressure profile. Lithium pellets were found to be more effective than deuterium pellets in raising q{sub 0}. {copyright} {ital 1997 American Institute of Physics.}

  13. Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak

    Science.gov (United States)

    Faust, I. C.; Brunner, D.; LaBombard, B.; Parker, R. R.; Terry, J. L.; Whyte, D. G.; Baek, S. G.; Edlund, E.; Hubbard, A. E.; Hughes, J. W.; Kuang, A. Q.; Reinke, M. L.; Shiraiwa, S.; Wallace, G. M.; Walk, J. R.

    2016-05-01

    For the first time, the power deposition of lower hybrid RF waves into the edge plasma of a diverted tokamak has been systematically quantified. Edge deposition represents a parasitic loss of power that can greatly impact the use and efficiency of Lower Hybrid Current Drive (LHCD) at reactor-relevant densities. Through the use of a unique set of fast time resolution edge diagnostics, including innovative fast-thermocouples, an extensive set of Langmuir probes, and a Lyα ionization camera, the toroidal, poloidal, and radial structure of the power deposition has been simultaneously determined. Power modulation was used to directly isolate the RF effects due to the prompt ( t 1.0 × 10 20 (m-3)). Results will be shown addressing the distribution of power within the SOL, including the toroidal symmetry and radial distribution. These characteristics are important for deducing the cause of the reduced LHCD efficiency at high density and motivate the tailoring of wave propagation to minimize SOL interaction, for example, through the use of high-field-side launch.

  14. Studies of EDA H-mode in Alcator C-Mod

    International Nuclear Information System (INIS)

    Studies of the enhanced Dα H-mode (EDA) have been extended to include ohmic plasmas. No clear difference in the EDA/ELMfree boundary or in other phenomenology are seen between ohmic and ICRF-heated plasmas, suggesting that neither the effect of ion tails nor direct RF/edge plasma interaction plays a role in EDA. Edge safety factor (q95) is the principal variable which determines which regime a discharge will be in. When q95 is greater than 4.0 for standard-shaped plasmas, the discharge is almost always EDA, while when it is less than 3.5, the plasma is almost always ELMfree. New edge diagnostics have allowed measurement of pedestal profiles with resolution of the order of 1 mm. Sudden changes in profile widths are not seen when the plasma makes a transition from EDA to ELMfree; however, the widths do vary with the same parameters that determine the EDA/ELMfree boundary. Strong edge-density fluctuations are observed to accompany EDA and may be responsible for the change in particle transport which is observed. The fluctuations have a quasi-coherent component whose frequency varies inversely with the pedestal width as measured by a visible continuum diagnostic. (author)

  15. Nonaxisymmetric field effects on Alcator C-Moda)

    Science.gov (United States)

    Wolfe, S. M.; Hutchinson, I. H.; Granetz, R. S.; Rice, J.; Hubbard, A.; Lynn, A.; Phillips, P.; Hender, T. C.; Howell, D. F.; La Haye, R. J.; Scoville, J. T.

    2005-05-01

    A set of external coils (A-coils) capable of producing nonaxisymmetric, predominantly n =1, fields with different toroidal phase and a range of poloidal mode m spectra has been used to determine the threshold amplitude for mode locking over a range of plasma parameters in Alcator C-Mod [I. H. Hutchinson, R. Boivin, F. Bombarda, P. Bonoli, S. Fairfax, C. Fiore, J. Goetz, S. Golovato, R. Granetz, M. Greenwald et al., Phys. Plasmas 1, 1511 (1994)]. The threshold perturbations and parametric scalings, expressed in terms of (B21/BT), are similar to those observed on larger, lower field devices. The threshold is roughly linear in density, with typical magnitudes of order 10-4. This result implies that locked modes should not be significantly more problematic for the International Thermonuclear Experimental Reactor [I. P. B. Editors, Nucl. Fusion 39, 2286 (1999)] than for existing devices. Coordinated nondimensional identity experiments on the Joint European Torus [Fusion Technol. 11, 13 (1987)], DIII-D [Fusion Technol. 8, 441 (1985)], and C-Mod, with matching applied mode spectra, have been carried out to determine more definitively the field and size scalings. Locked modes on C-Mod are observed to result in braking of core toroidal rotation, modification of sawtooth activity, and significant reduction in energy and particle confinement, frequently leading to disruptions. Intrinsic error fields inferred from the threshold studies are found to be consistent in amplitude and phase with a comprehensive model of the sources of field errors based on "as-built" coil and bus-work details and coil imperfections inferred from measurements using in situ magnetic diagnostics on dedicated test pulses. Use of the A-coils to largely cancel the 2/1 component of the intrinsic nonaxisymmetric field has led to expansion of the accessible operating space in C-Mod, including operation up to 2 MA plasma current at 8 T.

  16. Experimental studies of edge turbulence and confinement in Alcator C-Moda)

    Science.gov (United States)

    Cziegler, I.; Terry, J. L.; Hughes, J. W.; LaBombard, B.

    2010-05-01

    The steep gradient edge region and scrape-off-layer (SOL) on the low-field-side of Alcator C-Mod [I. H. Hutchinson, R. Boivin, F. Bombarda et al., Phys. Plasmas 1, 1511 (1994)] tokamak plasmas are studied using gas-puff-imaging diagnostics. In L-mode plasmas, the region extending ˜2 cm inside the magnetic separatrix has fluctuations showing a broad, turbulent spectrum, propagating in the electron diamagnetic drift direction, whereas features in the open field line region propagate in the ion diamagnetic drift direction. This structure is robust against toroidal field strength, poloidal null-point geometry, plasma current, and plasma density. Global parameter dependence of spectral and spatial structure of the turbulence inside the separatrix is explored and characterized, and both the intensity and spectral distributions are found to depend strongly on the plasma density normalized to the tokamak density limit. In H-mode discharges the fluctuations at and inside the magnetic separatrix show fundamentally different trends compared to L-mode, with the electron diamagnetic direction propagating turbulence greatly reduced in ELM-free [F. Wagner et al., Proceedings of the Thirteenth Conference on Plasma Physics and Controlled Nuclear Fusion Research (IAEA, Vienna, 1982), Vol. I, p. 277], and completely dominated by the modelike structure of the quasicoherent mode in enhanced D-alpha regimes [A. E. Hubbard, R. L. Boivin, R. S. Granetz et al., Phys. Plasmas 8, 2033 (2001)], while the normalized SOL turbulence is largely unaffected.

  17. Two dimensional radiated power diagnostics on Alcator C-Moda)

    Science.gov (United States)

    Reinke, M. L.; Hutchinson, I. H.

    2008-10-01

    The radiated power diagnostics for the Alcator C-Mod tokamak have been upgraded to measure two dimensional structure of the photon emissivity profile in order to investigate poloidal asymmetries in the core radiation. Commonly utilized unbiased absolute extreme ultraviolet (AXUV) diode arrays view the plasma along five different horizontal planes. The layout of the diagnostic set is shown and the results from calibrations and recent experiments are discussed. Data showing a significant, 30%-40%, inboard/outboard emissivity asymmetry during ELM-free H-mode are presented. The ability to use AXUV diode arrays to measure absolute radiated power is explored by comparing diode and resistive bolometer-based emissivity profiles for highly radiative L-mode plasmas seeded with argon. Emissivity profiles match in the core but disagree radially outward resulting in an underprediction of Prad of nearly 50% by the diodes compared to Prad determined using resistive bolometers.

  18. Performance Assessment of the C-Mod Multi-Spectral Line Polarization MSE (MSE-MSLP) Diagnostic

    Science.gov (United States)

    Scott, Steven; Mumgaard, Robert; Khoury, Matthew

    2015-11-01

    The accuracy of the Alcator C-Mod Motional Stark Effect (MSE) diagnostic is limited primarily by partially polarized background light that varies rapidly both in time (1 ms) and space - factor 10 variations are observed between adjacent spatial channels. ITER is likely to operate in a similar regime. Visible Bremsstrahlung, divertor molecular D2 emission, and glowing invessel structures generate unpolarized light that becomes partially polarized upon reflection. Because all three sources are broadband, the background light can be measured in real-time at wavelengths close to the MSE spectrum, thereby allowing the background to be interpolated in wavelength rather than in time. A 10-spatial-channel, 4-wavelength MSE-MSLP system has been developed using polarization polychromators that measure simultaneously the MSE pi- and sigma- lines as well as two nearby wavelengths that were chosen to avoid both the MSE spectrum and all known impurity lines on each sightline. Initial performance evaluation indicates that the background channel measurements faithfully track the background light in the pi- and sigma- lines. The improvement in accuracy of pitch-angle measurements and increased diagnostic flexibility over a wide range of plasma conditions will be reported. This work is supported by USDoE awards DE-FC02-99ER54512 and DE-AC02-09CH11466.

  19. Simulated plasma facing component measurements for an in situ surface diagnostic on Alcator C-Moda)

    Science.gov (United States)

    Hartwig, Z. S.; Whyte, D. G.

    2010-10-01

    The ideal in situ plasma facing component (PFC) diagnostic for magnetic fusion devices would perform surface element and isotope composition measurements on a shot-to-shot (˜10 min) time scale with ˜1 μm depth and ˜1 cm spatial resolution over large areas of PFCs. To this end, the experimental adaptation of the customary laboratory surface diagnostic—nuclear scattering of MeV ions—to the Alcator C-Mod tokamak is being guided by ACRONYM, a Geant4 synthetic diagnostic. The diagnostic technique and ACRONYM are described, and synthetic measurements of film thickness for boron-coated PFCs are presented.

  20. Production of internal transport barriers via self-generated mean flows in Alcator C-Moda)

    Science.gov (United States)

    Fiore, C. L.; Ernst, D. R.; Podpaly, Y. A.; Mikkelsen, D.; Howard, N. T.; Lee, Jungpyo; Reinke, M. L.; Rice, J. E.; Hughes, J. W.; Ma, Y.; Rowan, W. L.; Bespamyatnov, I.

    2012-05-01

    New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak [E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007)]. These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti ≈ Te, and with monotonic q profiles (qmin 1.5 × 105 rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.

  1. Novel energy resolving x-ray pinhole camera on Alcator C-Moda)

    Science.gov (United States)

    Pablant, N. A.; Delgado-Aparicio, L.; Bitter, M.; Brandstetter, S.; Eikenberry, E.; Ellis, R.; Hill, K. W.; Hofer, P.; Schneebeli, M.

    2012-10-01

    A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of ≈1 cm, an energy resolution of ≈1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009), 10.1107/S0909049509009911] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

  2. Measurement and simulation of ICRF wave intensity with a recalibrated phase contrast imaging diagnostic on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Tsujii, N., E-mail: tsujii@k.u-tokyo.ac.jp [The University of Tokyo, Kashiwa (Japan); Porkolab, M.; Bonoli, P. T.; Edlund, E. M.; Ennever, P. C.; Lin, Y.; Wright, J. C.; Wukitch, S. J. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts (United States); Jaeger, E. F. [XCEL Engineering, Oak Ridge, Tennessee (United States); Green, D. L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States); Harvey, R. W. [CompX, Del Mar, California (United States)

    2015-12-10

    Waves in the ion cyclotron range of frequencies (ICRF) are one of the major tools to heat fusion plasmas. Full-wave simulations are essential to predict the wave propagation and absorption quantitatively, and it is important that these codes be validated against actual experimental measurements. In this work, the absolute intensity of the ICRF waves previously measured with a phase contrast imaging diagnostic was recalibrated and compared once more with full-wave predictions. In the earlier work, significant discrepancies were found between the measured and the simulated mode converted wave intensity [N. Tsujii et al., Phys. Plasmas 19, 082508]. With the new calibration of the detector array, the measured mode converted wave intensity is now in much better agreement with the full-wave predictions. The agreement is especially good for comparisons performed close to the antenna.

  3. Measurements of electron temperature profiles on Alcator C-Mod using a novel energy-resolving x-ray camera

    Science.gov (United States)

    Maddox, J.; Delgado, L.; Pablant, N.; Hill, K. W.; Bitter, M.; Efthimion, P.; Rice, J.

    2015-11-01

    The most common electron temperature diagnostics, Thomson Scattering (TS) and Electron Cyclotron Emission (ECE), both require large diagnostic footprints and expensive optics. Another electron temperature diagnostic is the Pulse-Height-Analysis (PHA) system, which derives the electron temperature from the x-ray bremsstrahlung continuum. However, the main disadvantage of the PHA method is poor temporal resolution of the Si(Li) diode detectors. This paper presents a novel x-ray pinhole camera, which uses a pixilated Pilatus detector that allows single photon counting at a rate 2MHz per pixel and the setting of energy thresholds. The detector configuration is optimized by Shannon-sampling theory, such that spatial profiles of the x-ray continuum intensity can be obtained simultaneously for different energies, in the range from 4 to 16 keV. The exponential-like dependence of the x-ray intensity with photon energies is compared with a model describing the Be filter, attenuation in air, and detector efficiency, as well as different sets of energy thresholds. Electron temperature measurements are compared with TS and ECE measurements. This work was supported by the US DOE Contract No.DE-AC02-09CH11466 and the DoE Summer Undergraduate Laboratory Internship (SULI) program.

  4. Measurement and simulation of ICRF wave intensity with a recalibrated phase contrast imaging diagnostic on Alcator C-Mod

    International Nuclear Information System (INIS)

    Waves in the ion cyclotron range of frequencies (ICRF) are one of the major tools to heat fusion plasmas. Full-wave simulations are essential to predict the wave propagation and absorption quantitatively, and it is important that these codes be validated against actual experimental measurements. In this work, the absolute intensity of the ICRF waves previously measured with a phase contrast imaging diagnostic was recalibrated and compared once more with full-wave predictions. In the earlier work, significant discrepancies were found between the measured and the simulated mode converted wave intensity [N. Tsujii et al., Phys. Plasmas 19, 082508]. With the new calibration of the detector array, the measured mode converted wave intensity is now in much better agreement with the full-wave predictions. The agreement is especially good for comparisons performed close to the antenna

  5. Heat-flux footprints for I-mode and EDA H-mode plasmas on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Terry, J.L., E-mail: terry@psfc.mit.edu [Plasma Science and Fusion Center, MIT, Cambridge, MA 02139 (United States); LaBombard, B.; Brunner, D.; Hughes, J.W.; Reinke, M.L.; Whyte, D.G. [Plasma Science and Fusion Center, MIT, Cambridge, MA 02139 (United States)

    2013-07-15

    IR thermography is used to measure the heat flux footprints on C-Mod’s outer target in I-mode and EDA H-mode plasmas. The footprint profiles are fit to a function with a simple physical interpretation. The fit parameter that is sensitive to the power decay length into the SOL, λ{sub SOL}, is ∼1–3× larger in I-modes than in H-modes at similar plasma current, which is the dominant dependence for the H-mode λ{sub SOL}. In contrast, the fit parameter sensitive to transport into the private-flux-zone along the divertor leg is somewhat smaller in I-mode than in H-mode, but otherwise displays no obvious dependence on I{sub p}, B{sub t}, or stored energy. A third measure of the footprint width, the “integral width”, is not significantly different between H- and I-modes. Also discussed are significant differences in the global power flows of the H-modes with “favorable”∇B drift direction and those of the I-modes with “unfavorable”∇B drift direction.

  6. Heat-flux footprints for I-mode and EDA H-mode plasmas on Alcator C-Mod

    International Nuclear Information System (INIS)

    IR thermography is used to measure the heat flux footprints on C-Mod’s outer target in I-mode and EDA H-mode plasmas. The footprint profiles are fit to a function with a simple physical interpretation. The fit parameter that is sensitive to the power decay length into the SOL, λSOL, is ∼1–3× larger in I-modes than in H-modes at similar plasma current, which is the dominant dependence for the H-mode λSOL. In contrast, the fit parameter sensitive to transport into the private-flux-zone along the divertor leg is somewhat smaller in I-mode than in H-mode, but otherwise displays no obvious dependence on Ip, Bt, or stored energy. A third measure of the footprint width, the “integral width”, is not significantly different between H- and I-modes. Also discussed are significant differences in the global power flows of the H-modes with “favorable”∇B drift direction and those of the I-modes with “unfavorable”∇B drift direction

  7. Characterization and performance of a field aligned ion cyclotron range of frequency antenna in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Wukitch, S. J.; Garrett, M. L.; Ochoukov, R.; Terry, J. L.; Hubbard, A.; Labombard, B.; Lau, C.; Lin, Y.; Lipschultz, B.; Miller, D.; Reinke, M. L.; Whyte, D. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Collaboration: Alcator C-Mod Team

    2013-05-15

    Ion cyclotron range of frequency (ICRF) heating is expected to provide auxiliary heating for ITER and future fusion reactors where high Z metallic plasma facing components (PFCs) are being considered. Impurity contamination linked to ICRF antenna operation remains a major challenge particularly for devices with high Z metallic PFCs. Here, we report on an experimental investigation to test whether a field aligned (FA) antenna can reduce impurity contamination and impurity sources. We compare the modification of the scrape of layer (SOL) plasma potential of the FA antenna to a conventional, toroidally aligned (TA) antenna, in order to explore the underlying physics governing impurity contamination linked to ICRF heating. The FA antenna is a 4-strap ICRF antenna where the current straps and antenna enclosure sides are perpendicular to the total magnetic field while the Faraday screen rods are parallel to the total magnetic field. In principle, alignment with respect to the total magnetic field minimizes integrated E|| (electric field along a magnetic field line) via symmetry. A finite element method RF antenna model coupled to a cold plasma model verifies that the integrated E|| should be reduced for all antenna phases. Monopole phasing in particular is expected to have the lowest integrated E||. Consistent with expectations, we observed that the impurity contamination and impurity source at the FA antenna are reduced compared to the TA antenna. In both L and H-mode discharges, the radiated power is 20%–30% lower for a FA-antenna heated discharge than a discharge heated with the TA-antennas. However, inconsistent with expectations, we observe RF induced plasma potentials (via gas-puff imaging and emissive probes to be nearly identical for FA and TA antennas when operated in dipole phasing). Moreover, the highest levels of RF-induced plasma potentials are observed using monopole phasing with the FA antenna. Thus, while impurity contamination and sources are indeed reduced with the FA antenna configuration, the mechanism determining the SOL plasma potential in the presence of ICRF and its impact on impurity contamination and sources remains to be understood.

  8. Characterization and performance of a field aligned ion cyclotron range of frequency antenna in Alcator C-Mod

    International Nuclear Information System (INIS)

    Ion cyclotron range of frequency (ICRF) heating is expected to provide auxiliary heating for ITER and future fusion reactors where high Z metallic plasma facing components (PFCs) are being considered. Impurity contamination linked to ICRF antenna operation remains a major challenge particularly for devices with high Z metallic PFCs. Here, we report on an experimental investigation to test whether a field aligned (FA) antenna can reduce impurity contamination and impurity sources. We compare the modification of the scrape of layer (SOL) plasma potential of the FA antenna to a conventional, toroidally aligned (TA) antenna, in order to explore the underlying physics governing impurity contamination linked to ICRF heating. The FA antenna is a 4-strap ICRF antenna where the current straps and antenna enclosure sides are perpendicular to the total magnetic field while the Faraday screen rods are parallel to the total magnetic field. In principle, alignment with respect to the total magnetic field minimizes integrated E|| (electric field along a magnetic field line) via symmetry. A finite element method RF antenna model coupled to a cold plasma model verifies that the integrated E|| should be reduced for all antenna phases. Monopole phasing in particular is expected to have the lowest integrated E||. Consistent with expectations, we observed that the impurity contamination and impurity source at the FA antenna are reduced compared to the TA antenna. In both L and H-mode discharges, the radiated power is 20%–30% lower for a FA-antenna heated discharge than a discharge heated with the TA-antennas. However, inconsistent with expectations, we observe RF induced plasma potentials (via gas-puff imaging and emissive probes to be nearly identical for FA and TA antennas when operated in dipole phasing). Moreover, the highest levels of RF-induced plasma potentials are observed using monopole phasing with the FA antenna. Thus, while impurity contamination and sources are indeed reduced with the FA antenna configuration, the mechanism determining the SOL plasma potential in the presence of ICRF and its impact on impurity contamination and sources remains to be understood

  9. The Fusion Science Research Plan for the Major U.S. Tokamaks. Advisory report

    International Nuclear Information System (INIS)

    In summary, the community has developed a research plan for the major tokamak facilities that will produce impressive scientific benefits over the next two years. The plan is well aligned with the new mission and goals of the restructured fusion energy sciences program recommended by FEAC. Budget increases for all three facilities will allow their programs to move forward in FY 1997, increasing their rate of scientific progress. With a shutdown deadline now established, the TFTR will forego all but a few critical upgrades and maximize operation to achieve a set of high-priority scientific objectives with deuterium-tritium plasmas. The DIII-D and Alcator C-Mod facilities will still fall well short of full utilization. Increasing the run time in vii DIII-D is recommended to increase the scientific output using its existing capabilities, even if scheduled upgrades must be further delayed. An increase in the Alcator C-Mod budget is recommended, at the expense of equal and modest reductions (~1%) in the other two facilities if necessary, to develop its capabilities for the long-term and increase its near-term scientific output.

  10. Interferometría láser heterodina para diagnóstico en plasmas de fusión. Experimentos y medidas realizados en el Stellarator TJ-II y el Tokamak C-MOD

    OpenAIRE

    Acedo Gallardo, Pablo

    2000-01-01

    La presente tesis describe la concepción, el diseño, la instalación y la obtención de primeros resultados de dos interferómetros láser heterodinos con dos longitudes de onda para la medida de densidades electrónicas en dos máquinas de fusión: el Stellarator T J-II (Centro de Investigaciones Energéticas, Mediambientales y Tecnológicas, Madrid) y el Tokamak Alcator C-Mod (Plasma Science and Fusion Center, MIT, EEUU). Este diagnóstico interferométrico de la densidad electrónica ba...

  11. Scrape-off layer reflectometer for Alcator C-Moda)

    Science.gov (United States)

    Lau, Cornwall; Hanson, Greg; Wilgen, John; Lin, Yijun; Wukitch, Steve

    2010-10-01

    A swept-frequency X-mode reflectometer is being built for Alcator C-Mod to measure the scrape-off layer density profiles at the top, middle, and bottom locations in front of both the new lower hybrid launcher and the new ion cyclotron range of frequencies antenna. The system is planned to operate between 100 and 146 GHz at sweep rates from 10 μs to 1 ms, and will cover a density range of approximately 1016-1020 m-3 at B0=5-5.4 T. To minimize the effects of density fluctuations, both differential phase and full phase reflectometry will be employed. Design, test data, and calibration results of this electronics system will be discussed. To reduce attenuation losses, tallguide (TE01) will be used for most of the transmission line system. Simulations of high mode conversion in tallguide components, such as e-plane hyperbolic secant radius of curvature bends, tapers, and horn antennas will be shown. Experimental measurements of the total attenuation losses of these components in the lower hybrid waveguide run will also be presented.

  12. Design of a correlation electron cyclotron emission diagnostic for Alcator C-Moda)

    Science.gov (United States)

    Sung, C.; White, A. E.; Irby, J. H.; Leccacorvi, R.; Vieira, R.; Oi, C. Y.; Peebles, W. A.; Nguyen, X.

    2012-10-01

    A correlation electron cyclotron emission (CECE) diagnostic has been installed in Alcator C-Mod. In order to measure electron temperature fluctuations, this diagnostic uses a spectral decorrelation technique. Constraints obtained with nonlinear gyrokinetic simulations guided the design of the optical system and receiver. The CECE diagnostic is designed to measure temperature fluctuations which have kθ ≤ 4.8 cm-1 (kθρs < 0.5) using a well-focused beam pattern. Because the CECE diagnostic is a dedicated turbulence diagnostic, the optical system is also flexible, which allows for various collimating lenses and antenna to be used. The system overview and the demonstration of its operability as designed are presented in this paper.

  13. First results of the SOL reflectometer on Alcator C-Moda)

    Science.gov (United States)

    Lau, C.; Hanson, G.; Lin, Y.; Wilgen, J.; Wukitch, S.; Labombard, B.; Wallace, G.

    2012-10-01

    A swept-frequency X-mode reflectometer has been built on Alcator C-Mod to measure the scrape-off layer (SOL) density profiles adjacent to the lower hybrid launcher. The reflectometer system operates between 100 and 146 GHz at sweep rates from 10 μs to 1 ms and covers a density range of ˜1016-1020 m-3 at B0 = 5-5.4 T. This paper discusses the analysis of reflectometer density profiles and presents first experimental results of SOL density profile modifications due to the application of lower hybrid range-of-frequencies power to L-mode discharges. Comparison between density profiles measured by the X-mode reflectometer and scanning Langmuir probes is also shown.

  14. A new interferometry-based electron density fluctuation diagnostic on Alcator C-Moda)

    Science.gov (United States)

    Kasten, C. P.; Irby, J. H.; Murray, R.; White, A. E.; Pace, D. C.

    2012-10-01

    The two-color interferometry diagnostic on the Alcator C-Mod tokamak has been upgraded to measure fluctuations in the electron density and density gradient for turbulence and transport studies. Diagnostic features and capabilities are described. In differential mode, fast phase demodulation electronics detect the relative phase change between ten adjacent, radially-separated (ΔR = 1.2 cm, adjustable), vertical-viewing chords, which allows for measurement of the line-integrated electron density gradient. The system can be configured to detect the absolute phase shift of each chord by comparison to a local oscillator, measuring the line-integrated density. Each chord is sensitive to density fluctuations with kR < 20.3 cm-1 and is digitized at up to 10 MS/s, resolving aspects of ion temperature gradient-driven modes and other long-wavelength turbulence. Data from C-Mod discharges is presented, including observations of the quasi-coherent mode in enhanced D-alpha H-mode plasmas and the weakly coherent mode in I-mode.

  15. Structure and motion of edge turbulence in the National Spherical Torus Experiment and Alcator C-Moda)

    Science.gov (United States)

    Zweben, S. J.; Maqueda, R. J.; Terry, J. L.; Munsat, T.; Myra, J. R.; D'Ippolito, D.; Russell, D. A.; Krommes, J. A.; LeBlanc, B.; Stoltzfus-Dueck, T.; Stotler, D. P.; Williams, K. M.; Bush, C. E.; Maingi, R.; Grulke, O.; Sabbagh, S. A.; White, A. E.

    2006-05-01

    In this paper we compare the structure and motion of edge turbulence observed in L-mode vs. H-mode plasmas in the National Spherical Torus Experiment (NSTX) [M. Ono, M. G. Bell, R. E. Bell et al., Plasma Phys. Controlled Fusion 45, A335 (2003)]. The radial and poloidal correlation lengths are not significantly different between the L-mode and the H-mode in the cases examined. The poloidal velocity fluctuations are lower and the radial profiles of the poloidal turbulence velocity are somewhat flatter in the H-mode compared with the L-mode plasmas. These results are compared with similar measurements Alcator C-Mod [E. Marmar, B. Bai, R. L. Boivin et al., Nucl. Fusion 43, 1610 (2003)], and with theoretical models.

  16. Phase contrast imaging measurements of reversed shear Alfvén eigenmodes during sawteeth in Alcator C-Moda)

    Science.gov (United States)

    Edlund, E. M.; Porkolab, M.; Kramer, G. J.; Lin, L.; Lin, Y.; Wukitch, S. J.

    2009-05-01

    Reversed shear Alfvén eigenmodes (RSAEs) have been observed with the phase contrast imaging diagnostic and Mirnov coils during the sawtooth cycle in Alcator C-mod [M. Greenwald et al., Nucl. Fusion 45, S109 (2005)] plasmas with minority ion-cyclotron resonance heating. Both down-chirping RSAEs and up-chirping RSAEs have been observed during the sawtooth cycle. Experimental measurements of the spatial structure of the RSAEs are compared to theoretical models based on the code NOVA [C. Z. Cheng and M. S. Chance, J. Comput. Phys. 71, 124 (1987)] and used to derive constraints on the q profile. It is shown that the observed RSAEs can be understood by assuming a reversed shear q profile (up chirping) or a q profile with a local maximum (down chirping) with q ≈1.

  17. Modification of ordinary-mode reflectometry system to detect lower-hybrid waves in Alcator C-Moda)

    Science.gov (United States)

    Baek, S. G.; Shiraiwa, S.; Parker, R. R.; Dominguez, A.; Kramer, G. J.; Marmar, E. S.

    2012-10-01

    Backscattering experiments to detect lower-hybrid (LH) waves have been performed in Alcator C-Mod, using the two modified channels (60 GHz and 75 GHz) of an ordinary-mode reflectometry system with newly developed spectral recorders that can continuously monitor spectral power at a target frequency. The change in the baseline of the spectral recorder during the LH wave injection is highly correlated to the strength of the X-mode non-thermal electron cyclotron emission. In high density plasmas where an anomalous drop in the lower hybrid current drive efficiency is observed, the observed backscattered signals are expected to be generated near the last closed flux surface, demonstrating the presence of LH waves within the plasma. This experimental technique can be useful in identifying spatially localized LH electric fields in the periphery of high-density plasmas.

  18. Fluctuating zonal flows in the I-mode regime in Alcator C-Moda)

    Science.gov (United States)

    Cziegler, I.; Diamond, P. H.; Fedorczak, N.; Manz, P.; Tynan, G. R.; Xu, M.; Churchill, R. M.; Hubbard, A. E.; Lipschultz, B.; Sierchio, J. M.; Terry, J. L.; Theiler, C.

    2013-05-01

    Velocity fields and density fluctuations of edge turbulence are studied in I-mode [F. Ryter et al., Plasma Phys. Controlled Fusion 40, 725 (1998)] plasmas of the Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] tokamak, which are characterized by a strong thermal transport barrier in the edge while providing little or no barrier to the transport of both bulk and impurity particles. Although previous work showed no clear geodesic-acoustic modes (GAM) on C-Mod, using a newly implemented, gas-puff-imaging based time-delay-estimate velocity inference algorithm, GAM are now shown to be ubiquitous in all I-mode discharges examined to date, with the time histories of the GAM and the I-mode specific [D. Whyte et al., Nucl. Fusion 50, 105005 (2010)] Weakly Coherent Mode (WCM, f = 100-300 kHz, Δf/f≈0.5, and kθ≈1.3 cm-1) closely following each other through the entire duration of the regime. Thus, the I-mode presents an example of a plasma state in which zero frequency zonal flows and GAM continuously coexist. Using two-field (density-velocity and radial-poloidal velocity) bispectral methods, the GAM are shown to be coupled to the WCM and to be responsible for its broad frequency structure. The effective nonlinear growth rate of the GAM is estimated, and its comparison to the collisional damping rate seems to suggest a new view on I-mode threshold physics.

  19. Investigation of lower hybrid physics through power modulation experiments on Alcator C-Moda)

    Science.gov (United States)

    Schmidt, A.; Bonoli, P. T.; Meneghini, O.; Parker, R. R.; Porkolab, M.; Shiraiwa, S.; Wallace, G.; Wright, J. C.; Harvey, R. W.; Wilson, J. R.

    2011-05-01

    Lower hybrid current drive (LHCD) is an attractive tool for off-axis current profile control in magnetically confined tokamak plasmas and burning plasmas (ITER), because of its high current drive efficiency. The LHCD system on Alcator C-Mod operates at 4.6 GHz, with ~ 1 MW of coupled power, and can produce a wide range of launched parallel refractive index (n||) spectra. A 32 chord, perpendicularly viewing hard x-ray camera has been used to measure the spatial and energy distribution of fast electrons generated by lower hybrid (LH) waves. Square-wave modulation of LH power on a time scale much faster than the current relaxation time does not significantly alter the poloidal magnetic field inside the plasma and thus allows for realistic modeling and consistent plasma conditions for different n|| spectra. Inverted hard x-ray profiles show clear changes in LH-driven fast electron location with differing n||. Boxcar binning of hard x-rays during LH power modulation allows for ~ 1 ms time resolution which is sufficient to resolve the build-up, steady-state, and slowing-down phases of fast electrons. Ray-tracing/Fokker-Planck modeling in combination with a synthetic hard x-ray diagnostic shows quantitative agreement with the x-ray data for high n|| cases. The time histories of hollow x-ray profiles have been used to measure off-axis fast electron transport in the outer half of the plasma, which is found to be small on a slowing down time scale.

  20. H-mode pedestal and threshold studies over an expanded operating space on Alcator C-Moda)

    Science.gov (United States)

    Hubbard, A. E.; Hughes, J. W.; Bespamyatnov, I. O.; Biewer, T.; Cziegler, I.; LaBombard, B.; Lin, Y.; McDermott, R.; Rice, J. E.; Rowan, W. L.; Snipes, J. A.; Terry, J. L.; Wolfe, S. M.; Wukitch, S.

    2007-05-01

    This paper reports on studies of the edge transport barrier and transition threshold of the high confinement (H) mode of operation on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)], over a wide range of toroidal field (2.6-7.86T) and plasma current (0.4-1.7MA). The H-mode power threshold and edge temperature at the transition increase with field. Barrier widths, pressure limits, and confinement are nearly independent of field at constant current, but the operational space at high B shifts toward higher temperature and lower density and collisionality. Experiments with reversed field and current show that scrape-off-layer flows in the high-field side depend primarily on configuration. In configurations with the B ×∇B drift away from the active X-point, these flows lead to more countercurrent core rotation, which apparently contributes to higher H-mode thresholds. In the unfavorable case, edge temperature thresholds are higher, and slow evolution of profiles indicates a reduction in thermal transport prior to the transition in particle confinement. Pedestal temperatures in this case are also higher than in the favorable configuration. Both high-field and reversed-field results suggest that parameters at the L-H transition are influencing the evolution and parameters of the H-mode pedestal.

  1. Development of a High Resolution X-Ray Imaging Crystal Spectrometer for Measurement of Ion-Temperature and Rotation-Velocity Profiles in Fusion Energy Research Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K W; Broennimann, Ch; Eikenberry, E F; Ince-Cushman, A; Lee, S G; Rice, J E; Scott, S

    2008-01-29

    A new imaging high resolution x-ray crystal spectrometer (XCS) has been developed to measure continuous profiles of ion temperature and rotation velocity in fusion plasmas. Following proof-of-principle tests on the Alcator C-Mod tokamak and the NSTX spherical tokamak, and successful testing of a new silicon, pixilated detector with 1 MHz count rate capability per pixel, an imaging XCS is being designed to measure full profiles of Ti and vφ on C-Mod. The imaging XCS design has also been adopted for ITER. Ion-temperature uncertainty and minimum measurable rotation velocity are calculated for the C-Mod spectrometer. The affects of x-ray and uclear-radiation background on the measurement uncertainties are calculated to predict performance on ITER.

  2. Development of a High Resolution X-Ray Imaging Crystal Spectrometer for Measurement of Ion-Temperature and Rotation-Velocity Profiles in Fusion Energy Research Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K W; Broennimann, Ch; Eikenberry, E F; Ince-Cushman, A; Lee, S G; Rice, J E; Scott, S

    2008-02-27

    A new imaging high resolution x-ray crystal spectrometer (XCS) has been developed to measure continuous profiles of ion temperature and rotation velocity in fusion plasmas. Following proof-of-principle tests on the Alcator C-Mod tokamak and the NSTX spherical tokamak, and successful testing of a new silicon, pixilated detector with 1MHz count rate capability per pixel, an imaging XCS is being designed to measure full profiles of Ti and vφ on C-Mod. The imaging XCS design has also been adopted for ITER. Ion-temperature uncertainty and minimum measurable rotation velocity are calculated for the C-Mod spectrometer. The affects of x-ray and nuclear-radiation background on the measurement uncertainties are calculated to predict performance on ITER.

  3. FY-2013 FES (Fusion Energy Sciences) Joint Research Target Report

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermacher, M. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Garofalo, A. M. [General Atomics, San Diego, CA (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hubbard, A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Maingi, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Whyte, D. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2013-09-30

    investigated. The research will strengthen the basis for extrapolation of stationary regimes which combine high energy confinement with good particle and impurity control, to ITER and other future fusion facilities for which avoidance of large ELMs is a critical issue. Data from the Alcator C-Mod tokamak (MIT), DIII-D tokamak (General Atomics), and NSTX spherical tokamak (PPPL) contribute to this report. Experiments specifically motivated by this research target were conducted on DIII-D, with a national team of researchers from GA, LLNL, PPPL, MIT and ORNL contributing. Both the Alcator C-Mod and NSTX-U teams contributed analysis of previously collected data, as those two facilities did not operate in FY2013. Within each of the three research groups, members from both the host institutions and collaborating institutions made critical contributions. Highlights from these research activities are provided, with additional details.

  4. FY-2013 FES (Fusion Energy Sciences) Joint Research Target Report

    Energy Technology Data Exchange (ETDEWEB)

    Fenstermacher, M. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Garofalo, A. M. [General Atomics, San Diego, CA (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hubbard, A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Maingi, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Whyte, D. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2013-09-30

    investigated. The research will strengthen the basis for extrapolation of stationary regimes which combine high energy confinement with good particle and impurity control, to ITER and other future fusion facilities for which avoidance of large ELMs is a critical issue. Data from the Alcator C-Mod tokamak (MIT), DIII-D tokamak (General Atomics), and NSTX spherical tokamak (PPPL) contribute to this report. Experiments specifically motivated by this research target were conducted on DIII-D, with a national team of researchers from GA, LLNL, PPPL, MIT and ORNL contributing. Both the Alcator C-Mod and NSTX-U teams contributed analysis of previously collected data, as those two facilities did not operate in FY2013. Within each of the three research groups, members from both the host institutions and collaborating institutions made critical contributions. Highlights from these research activities are provided below, with additional details provided in chapters 2-5.

  5. Diamagnetic measurements on the Alcator C tokamak

    International Nuclear Information System (INIS)

    A procedure for determining the total thermal energy content of a magnetically confined plasma from a measurement of the plasma magnetization has been successfully implemented on the Alcator C tokamak. When a plasma is confined by a magnetic field, the kinetic pressure of the plasma is supported by an interaction between the confining magnetic field and drift currents which flow in the plasma. These drift currents induce an additional magnetic field which can be measured by means of appropriately positioned pickup coils. From a measurement of this magnetic field and of the confining magnetic field, one can calculate the spatially averaged plasma pressure, which is related to the thermal energy content of the plasma by the equation of state of the plasma. The theory on which this measurement is based is described in detail. The fields and currents which flow in the plasma are related to the confining magnetic field and the plasma pressure by requiring that the plasma be in equilibrium, i.e., by balancing the forces due to pressure gradients against those due to magnetic interactions. The apparatus used to make this measurement is described and some example data analyses are carried out

  6. LPS impairs oxygen utilization in epithelia by triggering degradation of the mitochondrial enzyme Alcat1.

    Science.gov (United States)

    Zou, Chunbin; Synan, Matthew J; Li, Jin; Xiong, Sheng; Manni, Michelle L; Liu, Yuan; Chen, Bill B; Zhao, Yutong; Shiva, Sruti; Tyurina, Yulia Y; Jiang, Jianfei; Lee, Janet S; Das, Sudipta; Ray, Anuradha; Ray, Prabir; Kagan, Valerian E; Mallampalli, Rama K

    2016-01-01

    Cardiolipin (also known as PDL6) is an indispensable lipid required for mitochondrial respiration that is generated through de novo synthesis and remodeling. Here, the cardiolipin remodeling enzyme, acyl-CoA:lysocardiolipin-acyltransferase-1 (Alcat1; SwissProt ID, Q6UWP7) is destabilized in epithelia by lipopolysaccharide (LPS) impairing mitochondrial function. Exposure to LPS selectively decreased levels of carbon 20 (C20)-containing cardiolipin molecular species, whereas the content of C18 or C16 species was not significantly altered, consistent with decreased levels of Alcat1. Alcat1 is a labile protein that is lysosomally degraded by the ubiquitin E3 ligase Skp-Cullin-F-box containing the Fbxo28 subunit (SCF-Fbxo28) that targets Alcat1 for monoubiquitylation at residue K183. Interestingly, K183 is also an acetylation-acceptor site, and acetylation conferred stability to the enzyme. Histone deacetylase 2 (HDAC2) interacted with Alcat1, and expression of a plasmid encoding HDAC2 or treatment of cells with LPS deacetylated and destabilized Alcat1, whereas treatment of cells with a pan-HDAC inhibitor increased Alcat1 levels. Alcat1 degradation was partially abrogated in LPS-treated cells that had been silenced for HDAC2 or treated with MLN4924, an inhibitor of Cullin-RING E3 ubiquitin ligases. Thus, LPS increases HDAC2-mediated Alcat1 deacetylation and facilitates SCF-Fbxo28-mediated disposal of Alcat1, thus impairing mitochondrial integrity. PMID:26604221

  7. Edge energy transport barrier and turbulence in the I-mode regime on Alcator C-Moda)

    Science.gov (United States)

    Hubbard, A. E.; Whyte, D. G.; Churchill, R. M.; Cziegler, I.; Dominguez, A.; Golfinopoulos, T.; Hughes, J. W.; Rice, J. E.; Bespamyatnov, I.; Greenwald, M. J.; Howard, N.; Lipschultz, B.; Marmar, E. S.; Reinke, M. L.; Rowan, W. L.; Terry, J. L.

    2011-05-01

    We report extended studies of the I-mode regime [Whyte et al., Nucl. Fusion 50, 105005 (2010)] obtained in the Alcator C-Mod tokamak [Marmar et al., Fusion Sci. Technol. 51(3), 3261 (2007)]. This regime, usually accessed with unfavorable ion B × ∇B drift, features an edge thermal transport barrier without a strong particle transport barrier. Steady I-modes have now been obtained with favorable B × ∇B drift, by using specific plasma shapes, as well as with unfavorable drift over a wider range of shapes and plasma parameters. With favorable drift, power thresholds are close to the standard scaling for L-H transitions, while with unfavorable drift they are ˜ 1.5-3 times higher, increasing with Ip. Global energy confinement in both drift configurations is comparable to H-mode scalings, while density profiles and impurity confinement are close to those in L-mode. Transport analysis of the edge region shows a decrease in edge χeff, by typically a factor of 3, between L- and I-mode. The decrease correlates with a drop in mid-frequency fluctuations (f ˜ 50-150 kHz) observed on both density and magnetics diagnostics. Edge fluctuations at higher frequencies often increase above L-mode levels, peaking at f ˜ 250 kHz. This weakly coherent mode is clearest and has narrowest width (Δf/f ˜ 0.45) at low q95 and high Tped, up to 1 keV. The Er well in I-mode is intermediate between L- and H-mode and is dominated by the diamagnetic contribution in the impurity radial force balance, without the Vpol shear typical of H-modes.

  8. Observation of ion cyclotron range of frequencies mode conversion plasma flow drive on Alcator C-Moda)

    Science.gov (United States)

    Lin, Y.; Rice, J. E.; Wukitch, S. J.; Greenwald, M. J.; Hubbard, A. E.; Ince-Cushman, A.; Lin, L.; Marmar, E. S.; Porkolab, M.; Reinke, M. L.; Tsujii, N.; Wright, J. C.; Alcator C-Mod Team

    2009-05-01

    At modest H3e levels (n3He/ne˜8%-12%), in relatively low density D(H3e) plasmas, n¯e≤1.3×1020 m-3, heated with 50 MHz rf power at Bt0˜5.1 T, strong (up to 90 km/s) toroidal rotation (Vϕ) in the cocurrent direction has been observed by high-resolution x-ray spectroscopy on Alcator C-Mod. The change in central Vϕ scales with the applied rf power (≤30 km s-1 MW-1), and is generally at least a factor of 2 higher than the empirically determined intrinsic plasma rotation scaling. The rotation in the inner plasma (r /a≤0.3) responds to the rf power more quickly than that of the outer region (r /a≥0.7), and the rotation profile is broadly peaked for r /a≤0.5. Localized poloidal rotation (0.3≤r/a≤0.6) in the ion diamagnetic drift direction (˜2 km/s at 3 MW) is also observed, and similarly increases with rf power. Changing the toroidal phase of the antenna does not affect the rotation direction, and it only weakly affects the rotation magnitude. The mode converted ion cyclotron wave (MC ICW) has been detected by a phase contrast imaging system and the MC process is confirmed by two-dimensional full wave TORIC simulations. The simulations also show that the MC ICW is strongly damped on H3e ions in the vicinity of the MC layer, approximately on the same flux surfaces where the rf driven flow is observed. The flow shear in our experiment is marginally sufficient for plasma confinement enhancement based on the comparison of the E ×B shearing rate and gyrokinetic linear stability analysis.

  9. Transport-driven scrape-off layer flows and the x-point dependence of the L-H power threshold in Alcator C-Moda)

    Science.gov (United States)

    LaBombard, B.; Rice, J. E.; Hubbard, A. E.; Hughes, J. W.; Greenwald, M.; Granetz, R. S.; Irby, J. H.; Lin, Y.; Lipschultz, B.; Marmar, E. S.; Marr, K.; Mossessian, D.; Parker, R.; Rowan, W.; Smick, N.; Snipes, J. A.; Terry, J. L.; Wolfe, S. M.; Wukitch, S. J.

    2005-05-01

    Factor of ˜2 higher power thresholds for low- to high-confinement mode transitions (L-H) with unfavorable x-point topologies in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are linked to flow boundary conditions imposed by the scrape-off layer (SOL). Ballooning-like transport drives flow along magnetic field lines from low- to high-field regions with toroidal direction dependent on upper/lower x-point balance; the toroidal rotation of the confined plasma responds, exhibiting a strong counter-current rotation when B ×∇B points away from the x point. Increased auxiliary heating power (rf, no momentum input) leads to an L-H transition at approximately twice the edge electron pressure gradient when B ×∇B points away. As gradients rise prior to the transition, toroidal rotation ramps toward the co-current direction; the H mode is seen when the counter-current rotation imposed by the SOL flow becomes compensated. Remarkably, L-H thresholds in lower-limited discharges are identical to lower x-point discharges; SOL flows are also found similar, suggesting a connection.

  10. High-performance finite-difference time-domain simulations of C-Mod and ITER RF antennas

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Thomas G., E-mail: tgjenkins@txcorp.com; Smithe, David N., E-mail: smithe@txcorp.com [Tech-X Corporation, 5621 Arapahoe Avenue Suite A, Boulder, CO 80303 (United States)

    2015-12-10

    Finite-difference time-domain methods have, in recent years, developed powerful capabilities for modeling realistic ICRF behavior in fusion plasmas [1, 2, 3, 4]. When coupled with the power of modern high-performance computing platforms, such techniques allow the behavior of antenna near and far fields, and the flow of RF power, to be studied in realistic experimental scenarios at previously inaccessible levels of resolution. In this talk, we present results and 3D animations from high-performance FDTD simulations on the Titan Cray XK7 supercomputer, modeling both Alcator C-Mod’s field-aligned ICRF antenna and the ITER antenna module. Much of this work focuses on scans over edge density, and tailored edge density profiles, to study dispersion and the physics of slow wave excitation in the immediate vicinity of the antenna hardware and SOL. An understanding of the role of the lower-hybrid resonance in low-density scenarios is emerging, and possible implications of this for the NSTX launcher and power balance are also discussed. In addition, we discuss ongoing work centered on using these simulations to estimate sputtering and impurity production, as driven by the self-consistent sheath potentials at antenna surfaces.

  11. Pioneering Structural Solutions for Compact High Field Experiments Developed for the Alcator and the Ignitor Programs

    Science.gov (United States)

    Salvetti, M.; Coppi, B.

    2015-11-01

    Recently there has been an increased awareness of the fact that the line of research based on compact high field machines is the most promising to approach ignition conditions in DT burning plasmas and has acquired new perspectives for its applications. Then the technological solutions that have made these machines possible have become subject to new attention and, in some cases, to rediscovery. The Alcator Program and, followed by Ignitor Program, has led to invent the coupled air-core former poloidal field system that has made compact machine possible and has been adopted on all advanced toroidal machines that came after Alcator. A recently rediscovered solution aimed at reducing the mechanical stresses in the inner legs of the toroidal magnet coils is the ``Upper and Lower Bracing Rings'' system that has had a key role in the design of the Ignitor machine and its evolution. Another solution to minimize the machine dimensions while maintaining high toroidal fields, in order to achieve high plasma current densities, is that of ``bucking and wedging'' of the toroidal magnet by coupling it mechanically to the central solenoid. Sponsored in part by the U.S. DoE.

  12. The effects of main-ion dilution on turbulence in low q95 C-Mod ohmic plasmas, and comparisons with nonlinear GYRO

    Science.gov (United States)

    Ennever, P.; Porkolab, M.; Candy, J.; Staebler, G.; Reinke, M. L.; Rice, J. E.; Rost, J. C.; Ernst, D.; Hughes, J.; Baek, S. G.

    2016-08-01

    Recent experiments on C-mod seeding nitrogen into ohmic plasmas with q95 = 3.4 found that the seeding greatly reduced long-wavelength (ITG-scale) turbulence. The long-wavelength turbulence that was reduced by the nitrogen seeding was localized to the region of r /a ≈0.85 , where the turbulence is well above marginal stability (as evidenced by Qi/QGB≫1 ). The nonlinear gyrokinetic code GYRO was used to simulate the expected turbulence in these plasmas, and the simulated turbulent density fluctuations and turbulent energy fluxes quantitatively agreed with the experimental measurements both before and after the nitrogen seeding. Unexpectedly, the intrinsic rotation of the plasma was also found to be affected by the nitrogen seeding, in a manner apparently unrelated to a change in the electron-ion collisionality that was proposed by other experiments.

  13. Theoretical studies of lower hybrid current drive in the Alcator C tokamak

    International Nuclear Information System (INIS)

    Theoretical studies of lower hybrid current drive in the Alcator C tokamak using a simulation model is presented, the model incorporates a 1-D radial transport code to solve for the time evolution of the bulk plasma quantities

  14. Soft x-ray tomography on the Alcator C tokamak

    International Nuclear Information System (INIS)

    A soft x-ray tomography experiment has been performed on the Alcator C tokamak. An 80-chord array of detectors consisting of miniature PIN photodiodes was used to obtain tomographic reconstructions of the soft x-ray emissivity function's poloidal cross-section. The detectors are located around the periphery of the plasma at one toroidal location (top and bottom ports) and are capable of yielding useful information over a wide range of plasma operating parameters and conditions. The reconstruction algorithm employed makes no assumption whatsoever about plasma rotation, position, or symmetry. Its performance was tested, and it was found to work well and to be fairly insensitive to estimated levels of random and systematic errors in the data

  15. Time-Dependent Distribution Functions in C-Mod Calculated with the CQL3D-Hybrid-FOW, AORSA Full-Wave, and DC Lorentz Codes

    Science.gov (United States)

    Harvey, R. W. (Bob); Petrov, Yu. V.; Jaeger, E. F.; Berry, L. A.; Bonoli, P. T.; Bader, A.

    2015-11-01

    A time-dependent simulation of C-Mod pulsed ICRF power is made calculating minority hydrogen ion distribution functions with the CQL3D-Hybrid-FOW finite-orbit-width Fokker-Planck code. ICRF fields are calculated with the AORSA full wave code, and RF diffusion coefficients are obtained from these fields using the DC Lorentz gyro-orbit code. Prior results with a zero-banana-width simulation using the CQL3D/AORSA/DC time-cycles showed a pronounced enhancement of the H distribution in the perpendicular velocity direction compared to results obtained from Stix's quasilinear theory, in general agreement with experiment. The present study compares the new FOW results, including relevant gyro-radius effects, to determine the importance of these effects on the the NPA synthetic diagnostic time-dependence. The new NPA results give increased agreement with experiment, particularly in the ramp-down time after the ICRF pulse. Funded, through subcontract with Massachusetts Institute of Technology, by USDOE sponsored SciDAC Center for Simulation of Wave-Plasma Interactions.

  16. Lower hybrid heating in the Alcator A tokamak

    Science.gov (United States)

    Schuss, J. J.; Porkolab, M.; Takase, Y.; Cope, D.; Fairfax, S.; Greenwald, M.; Gwinn, D.; Hutchinson, I. H.; Kusse, B.; Marmar, E.

    1981-04-01

    The results of the moderate-power (P less than 100 kW) Alcator A lower-hybrid-heating experiment are presented. In this experiment, RF power densities of up to 8 kW per sq cm were achieved for 40-ms pulses. Both electron and ion heating were observed as the plasma density was varied. No impurity influx or density rise was observed because of the RF pulse. The ion heating, however, as evidenced by the formation of an energetic ion tail in the plasma center, occurred at a lower plasma density than expected from linear plasma wave theory. Furthermore, the electron heating observed at lower densities was not expected from linear waveguide-plasma coupling theory. Contrary to expectations, the ion heating was found to be independent of the waveguide phasing. These results, together with RF probe measurements in the edge plasma, suggest that the lower hybrid waves launched by the array may undergo strong scattering from parametric instabilities or density fluctuations near the plasma edge.

  17. Spectral measurements of fluctuating ω/sub pe/ radiation from Alcator C tokamak

    International Nuclear Information System (INIS)

    High resolution spectral measurements have been made of the fluctuating electron plasma frequency (ω/sub pe/) radiation from Alcator C. Three techniques have been used in making the measurements. Features as narrow as 350 kHz have been observed (Δf/f approx. = 6 x 10-6), impling that a highly coherent process is responsible for the emission

  18. Ion Bernstein wave experiments on the Alcator C tokamak

    International Nuclear Information System (INIS)

    Ion Bernstein wave experiments are carried out on the Alcator C tokamak to study wave excitation, propagation, absorption, and plasma heating due to wave power absorption. It is shown that ion Bernstein wave power is coupled into the plasma and follows the expected dispersion relation. The antenna loading is maximized when the hydrogen second harmonic layer is positioned just behind the antenna. Plasma heating results at three values of the toroidal magnetic field are presented. Central ion temperature increases of ΔT/sub i//Ti /approx lt/ 0.1 and density increases Δn/n 6s/sup /minus/1/ for plasmas within the density range 0.6 /times/ 1020m/sup /minus/3/ ≤ /bar n//sub e/ ≤ 4 /times/ 1020m/sup /minus/3/ and magnetic fields 2.4 ≥ ω/Ω/sub H/ ≥ 1.1. The density increases is usually accompanied by an improvement in the global particle confinement time relative to the Ohmic value. The ion heating rate is measured to be ΔT/sub i//P/sub rf/ ≅ 2-4.5 eV/kW at low densities. At higher densities /bar n//sub e/ ≤ 1.5 /times/ 1020m/sup /minus/3/ the ion heating rate dramatically decreases. It is shown that the decrease in the ion heating rate can be explained by the combined effects of wave scattering through the edge turbulence and the decreasing on energy confinement of these discharges with density. The effect of observed edge turbulence is shown to cause a broadening of the rf power deposition profile with increasing density. It is shown that the inferred value of the Ohmic ion thermal conduction, when compared to the Chang-Hinton neoclassical prediction, exhibits an increasing anomaly with increasing plasma density

  19. Plasma physics and controlled nuclear fusion research 1994. V. 1. Proceedings of the fifteenth international conference

    International Nuclear Information System (INIS)

    This volume contains (i) the traditional Artsimovich Memorial Lecture; (ii) nine presentations giving an overview of toroidal confinement systems (TFTR, JT-60U, JET, DIII-D, TORE SUPRA, Alcator C-Mod, JFT-2M and T-10 tokamaks and the Wendelstein 7-AS stellarator), (iii) twenty-three presentations on core plasma physics (mostly on charged-particle transport and improved confinement regimes), (iv) eight presentations on plasma heating and current drive, (v) twelve presentations on divertors and edge physics, (vi) thirteen on concept optimization (shaping of magnetic field configuration, control of plasma profiles and of disruptions, a.o.), and (vii) six on helical systems (stellarators, including torsatron/heliotron). Refs, figs and tabs

  20. D-D fusion neutron-spectra measurements and ion-temperature determination at Alcator C

    International Nuclear Information System (INIS)

    A neutron spectrometer system has been designed, assembled, and used to measure the D-D neutron spectrum at Alcator C. The design of the shielding and collimation was critical to the successful measurement of the spectrum and involved an integral approach in which the neutronics of the Alcator C was exploited to obtain a successful system. The system consists of a 3He ionization chamber mounted in a multi-component shield system. Essentially the outermost part of the shield and collimator has been designed to moderate the MeV-range neutrons to thermal energies. The inner part of the shield is designed to capture the thermalized neutrons with a minimum of gamma production. As a result, measurements during plasma discharges indicate that the ratio of the number of counts in the 2.45-MeV peak to the total number of neutron counts in the ion chamber is 1.67

  1. Observation of Lower-Hybrid Current Drive at High Densities in the Alcator C Tokamak

    Science.gov (United States)

    Porkolab, M.; Schuss, J. J.; Lloyd, B.; Takase, Y.; Texter, S.; Bonoli, P.; Fiore, C.; Gandy, R.; Gwinn, D.; Lipschultz, B.; Marmar, E.; Pappas, D.; Parker, R.; Pribyl, P.

    1984-07-01

    A quasi-steady-state lower-hybrid current-drive operation is demonstrated in the Alcator C tokamak at densities up to n―e~=1×1014 cm-3. The current-drive efficiency is measured experimentally over a wide range of densities and magnetic fields. The radial distribution of high-energy x rays indicates that the current-carrying electrons peak near the plasma axis.

  2. Energy Confinement of High-Density Pellet-Fueled Plasmas in the Alcator C Tokamak

    Science.gov (United States)

    Greenwald, M.; Gwinn, D.; Milora, S.; Parker, J.; Parker, R.; Wolfe, S.; Besen, M.; Camacho, F.; Fairfax, S.; Fiore, C.; Foord, M.; Gandy, R.; Gomez, C.; Granetz, R.; Labombard, B.; Lipschultz, B.; Lloyd, B.; Marmar, E.; McCool, S.; Pappas, D.; Petrasso, R.; Pribyl, P.; Rice, J.; Schuresko, D.; Takase, Y.; Terry, J.; Watterson, R.

    1984-07-01

    A series of pellet-fueling experiments has been carried out on the Alcator C tokamak. High-speed hydrogen pellets penetrate to within a few centimeters of the magnetic axis, raise the plasma density, and produce peaked density profiles. Energy confinement is observed to increase over similar discharges fueled only by gas puffing. In this manner record values of electron density, plasma pressure, and Lawson number (n τ) have been achieved.

  3. Critical need for MFE: the Alcator DX advanced divertor test facility

    Science.gov (United States)

    Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Wolf, S.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hutchinson, I.; Hubbard, A.; Hughes, J.; Lin, Y.; Lipschultz, B.; Parker, R.; Porkolab, M.; Reinke, M.; Rice, J.; Shiraiwa, S.; Terry, J.; Theiler, C.; Wallace, G.; White, A.; Whyte, D.; Wukitch, S.

    2013-10-01

    Three critical challenges must be met before a steady-state, power-producing fusion reactor can be realized: how to (1) safely handle extreme plasma exhaust power, (2) completely suppress material erosion at divertor targets and (3) do this while maintaining a burning plasma core. Advanced divertors such as ``Super X'' and ``X-point target'' may allow a fully detached, low temperature plasma to be produced in the divertor while maintaining a hot boundary layer around a clean plasma core - a potential game-changer for magnetic fusion. No facility currently exists to test these ideas at the required parallel heat flux densities. Alcator DX will be a national facility, employing the high magnetic field technology of Alcator combined with high-power ICRH and LHCD to test advanced divertor concepts at FNSF/DEMO power exhaust densities and plasma pressures. Its extended vacuum vessel contains divertor cassettes with poloidal field coils for conventional, snowflake, super-X and X-point target geometries. Divertor and core plasma performance will be explored in regimes inaccessible in conventional devices. Reactor relevant ICRF and LH drivers will be developed, utilizing high-field side launch platforms for low PMI. Alcator DX will inform the conceptual development and accelerate the readiness-for-deployment of next-step fusion facilities.

  4. D-D neutron energy-spectra measurements in Alcator C

    International Nuclear Information System (INIS)

    Measurements of energy spectra of neutrons produced during high density (anti n/sub e/ > 2 x 1014 cm-3) deuterium discharges have been performed using a proton-recoil (NE 213) spectrometer. A two foot section of light pipe (coupling the scintillator and photomultiplier) was used to extend the scintillator into a diagnostic viewing port to maximize the neutron detection efficiency while not imposing excessive magnetic shielding requirements. A derivative unfolding technique was used to deduce the energy spectra. The results showed a well defined peak at 2.5 MeV which was consistent with earlier neutron flux measurements on Alcator C that indicated the neutrons were of thermonuclear origin

  5. Numerical modeling of a fast-neutron collimator for the Alcator A fusion device

    International Nuclear Information System (INIS)

    A numerical procedure is developed to analyze neutron collimators used for spatial neutron measurements of plasma neutrons. The procedure is based upon Monte-Carlo methods and uses a standard Monte-Carlo code. The specific developments described herein involve a new approach to represent complex spatial details in a method that is conservative of computer time, retains accuracy and required only modest changes in already-developed Monte-Carlo procedures. The procedure was used to model the Alcator A collimator. The collimator consists of 448 cells and has a measured spatial point source response of 0.7 cm. The numerical procedure successfully predicts this response

  6. Preparing the Alcator C bolometer system for use on MTX (Microwave Tokamak Experiment)

    Science.gov (United States)

    Marinak, Marty

    1988-02-01

    The Alcator C bolometer array has been modified to be compatible with electron cyclotron heating on the Microwave Tokamak Experiment. Fine wire mesh screens are mounted on the front of the bolometer collimator tubes to attenuate microwave heating of the bolometers. Structural changes eliminate openings in the seams of the bolometer housing, which represent pathways for microwaves to enter the system. This paper outlines the operational principles of the bolometer system, discusses the measured and predicted performance characteristics of the bolometer array, and includes a concise guide to the operation of the bolometer controller.

  7. High gain free electron laser for heating and current drive in the ALCATOR-C tokamak

    International Nuclear Information System (INIS)

    The free electron laser (FEL) particle simulation code, FRED, has been used to examine the design of an FEL for amplifying radiation in the one to two millimeter wavelength range for use in electron heating and current drive in a tokamak device such as ALCATOR-C. As a desired design goal a peak output power of 8 GW, with a minimum input power in the 1 to 100 watt range has been used. The effects of electron beam current, energy and brightness, laser frequency and input power as well as wiggler wavelength and overall wiggler length on the performance of the FEL have been examined

  8. Spectroscopic diagnostics of high temperature plasmas

    International Nuclear Information System (INIS)

    A three-year research program for the development of novel XUV spectroscopic diagnostics for magnetically confined fusion plasmas is proposed. The new diagnostic system will use layered synthetic microstructures (LSM) coated, flat and curved surfaces as dispersive elements in spectrometers and narrow band XUV filter arrays. In the framework of the proposed program we will develop impurity monitors for poloidal and toroidal resolved measurements on PBX-M and Alcator C-Mod, imaging XUV spectrometers for electron density and temperature fluctuation measurements in the hot plasma core in TEXT or other similar tokamaks and plasma imaging devices in soft x-ray light for impurity behavior studies during RF heating on Phaedrus T and carbon pellet ablation in Alcator C-Mod. Recent results related to use of multilayer in XUV plasma spectroscopy are presented. We also discuss the latest results reviewed to qo and local poloidal field measurements using Zeeman polarimetry

  9. Experimental study of visible and ultraviolet impurity emission from the Alcator C tokamak

    International Nuclear Information System (INIS)

    Densities of carbon, oxygen, and silicon in Alcator C tokamak plasmas have been computed from spectroscopic measurements of the absolute brightnesses of visible and ultraviolet emission lines in combination with a one dimensional numerical calculation which models the charge state and emissivity profiles. Profiles of all the charge states of a particular impurity were calculated by utilizing independent measurements of plasma density and temperature and solving the coupled system of transport and rate equations connecting the ionization states. These profiles were then used to calculate emissivity and brightness profiles by solving the matrix equation relating the level populations through atomic processes such as electron impact excitation, de-excitation, spontaneous emission and cascades from upper levels. Good agreement was found between predicted impurity line brightnesses and experimentally measured brightnesses of different charge states. Three different types of limiter materials, molybdenum, graphite and SiC coated graphite have been used on Alcator C. It was determined that the principal impurities in the plasma, under most conditions, depends upon the type of limiter being used. However, the sources of the impurities are both the wall and the limiters, since it was observed that the wall becomes coated with limiter material due to plasma discharges

  10. RF heating and current drive experiments on the Alcator C and Versator II tokamaks

    International Nuclear Information System (INIS)

    Lower hybrid heating and current drive experiments on the Alcator C tokamak (R = 0.64 m, a = 0.165 m, molybdenum limiters) were performed at a frequency of 4.6 GHz with net injected rf powers up to P/sub rf/ ≤ 1.5 MW. Recent experiments have focused on energy confinement studies in lower hybrid current-driven (LHCD) and LHRF heated Ohmic discharges, and sawtooth stabilization in combined LHCD-OH driven discharges at densities n-bar/sub e/ ≤ 1.4 x 1020 m-3. Ion Bernstein wave heating experiments were also carried out in Alcator C at a frequency of f = 183 MHz at power levels P/sub rf/ ≤ 200 kW. Significant heating (ΔT/sub i/ ≤ 400 eV) was observed at ω/ω/sub CH/ ≅ 1.5, 2.5 and ω/ω/sub CD/ ≅ 2.5 at densities n-bar/sub e/ ≅ 1 x 1020 m-3. In the Versator II tokamak, particle confinement improvement (by factors of ≅2) was observed in the presence of 2.45 GHz lower hybrid current drive

  11. Poloidal asymmetries in the limiter shadow plasma of the Alcator C tokamak. Volume 1

    International Nuclear Information System (INIS)

    This thesis investigates conditions which exist in the limiter shadow plasma of the Alcator C tokamak. The understanding of this edge plasma region is approached from both experimental and theoretical points of view. First, a general overview of edge plasma physical processes is presented. Simple edge plasma models and conditions which can theoretically result in a poloidally asymmetric edge plasma are discussed. A review of data obtained from previous diagnostics in the Alcator C edge plasma is then used to motivate the development of a new edge plasma diagnostic system (DENSEPACK) to experimentally investigate poloidal asymmetries in this region. The bulk of this thesis focuses on the marked poloidal asymmetries detected by this poloidal probe array and possible mechanisms which might support such asymmetries on a magnetic flux surface. In processing the probe data, some important considerations on fitting Langmuir probe characteristics are identified. The remainder of this thesis catalogues edge versus central plasma parameter dependences. Regression analysis techniques are applied to characterize edge density for various central plasma parameters. Edge plasma conditions during lower hybrid radio frequency heating and pellet injection are also discussed

  12. RF heating and current drive experiments on the Alcator C and Versator II tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Porkolab, M.; Bonoli, P.; Chen, K.I.; Fiore, C.; Granetz, R.; Griffin, D.; Gwinn, D.; Knowlton, S.; Lipschultz, B.; Luckhardt, S.C.

    1986-11-01

    Lower hybrid heating and current drive experiments on the Alcator C tokamak (R = 0.64 m, a = 0.165 m, molybdenum limiters) were performed at a frequency of 4.6 GHz with net injected rf powers up to P/sub rf/ less than or equal to 1.5 MW. Recent experiments have focused on energy confinement studies in lower hybrid current-driven (LHCD) and LHRF heated Ohmic discharges, and sawtooth stabilization in combined LHCD-OH driven discharges at densities n-bar/sub e/ less than or equal to 1.4 x 10/sup 20/ m/sup -3/. Ion Bernstein wave heating experiments were also carried out in Alcator C at a frequency of f = 183 MHz at power levels P/sub rf/ less than or equal to 200 kW. Significant heating (..delta..T/sub i/ less than or equal to 400 eV) was observed at ..omega../..omega../sub CH/ approx. = 1.5, 2.5 and ..omega../..omega../sub CD/ approx. = 2.5 at densities n-bar/sub e/ approx. = 1 x 10/sup 20/ m/sup -3/. In the Versator II tokamak, particle confinement improvement (by factors of approx. =2) was observed in the presence of 2.45 GHz lower hybrid current drive.

  13. Lower-hybrid-heating experiments on the Alcator C and the Versator II Tokamaks

    Science.gov (United States)

    Porkolab, M.; Schuss, J. J.; Takase, Y.; Texter, S.; Fiore, C. L.; Gandy, R.; Greenwald, M. J.; Gwinn, D. A.; Lipschultz, B.; Marmar, E. S.

    Initial results from lower hybrid wave heating experiments carried out on the MIT Alcator-C and Versator II Tokamak are reported. In the Alcator-C experiments a 4 waveguide array, with internally brazed ceramic windows was used to inject 160 kW of microwave power at 4.6 GHz into the plasma with nO less than or equal to 1 x 10(15) cm(+3), and BO less than or equal to 12 T. The RF coupling studies show optimal coupling when the local density at the waveguide mouth is 25 to 50 times overdense. Heating experiments show an ion tail formation in hydrogen discharge peaking at a density of anti-n approx. = 2.7 x 10(14) cm(+3) at B = 8.9 T, and bulk ion heating at a density of anti n approx. = 1.5 x 10(14) c(+3) at B approx. = 11 T. Evidence of RF current enhancement has been observed at a density of n approx. = 3 x 10(13) cm (+3). Doppler broadening of the OVII and NVI lines shows a (RADICAL)T/sub i/= 50 eV rise in the bulk ion temperature. A significant RF produced ion tail is also observed by charge exchange analysis. A toroidal ray tracing code and a 1-D transport code to study the heating density bands and heating efficiencies were successfully combined.

  14. Time-dependent distribution functions and resulting synthetic NPA spectra in C-Mod calculated with the CQL3D-Hybrid-FOW, AORSA full-wave, and DC Lorentz codes

    Science.gov (United States)

    Harvey, R. W.; Petrov, Yu.; Jaeger, E. F.; Berry, L. A.; Bonoli, P. T.; Bader, A.

    2015-12-01

    A time-dependent simulation of C-Mod pulsed TCRF power is made obtaining minority hydrogen ion distributions with the CQL3D-Hybrid-FOW finite-orbit-width Fokker-Planck code. Cyclotron-resonant TCRF fields are calculated with the AORSA full wave code. The RF diffusion coefficients used in CQL3D are obtained with the DC Lorentz gyro-orbit code for perturbed particle trajectories in the combined equilibrium and TCRF electromagnetic fields. Prior results with a zero-banana-width simulation using the CQL3D/AORSA/DC time-cycles showed a pronounced enhancement of the H distribution in the perpendicular velocity direction compared to results obtained from Stix's quasilinear theory, and this substantially increased the rampup rate of the observed vertically-viewed neutral particle analyzer (NPA) flux, in general agreement with experiment. However, ramp down of the NPA flux after the pulse, remained long compared to the experiment. The present study compares the new FOW results, including relevant gyro-radius effects, to determine the importance of these new effects on the the NPA time-dependence.

  15. Plasma research. Final report, October 1, 1968--December 31, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Bekefi, G.; Coppi, B.; Parker, R.R.

    1976-01-01

    The research in plasma physics and controlled thermonuclear research at M.I.T. has evolved from a relatively long tradition of basic theoretical and experimental contributions, during the period covered by this contract. A major commitment to research in magnetically confined plasmas was undertaken with the Alcator program that began in 1969 and with the theoretical effort necessary to back this up. The Alcator A device was brought to successful operation and, after the identification of a sequence of plasma regimes that have been realized in it, let to attainment record values of plasma density, of the confinement parameter n tau, and of the degree of plasma purity. A second more advanced device, Alcator C, has been designed and is presently under construction. A line of toroidal experiments characterized by relatively low cost and extreme simplicity has been developed in order to study basic plasma physics problems related to magnetic confinement and relevant processes of plasma decontamination. The devices that have been operated are Versator I, now discontinued, Rector, with non-circular cross section, Erasmus, with small aspect ratio and Versator II. A number of theoretical contributions concerning the interpretation of the regimes found in Alcator, runaway phenomena, new trapped particle instabilities, internal resistive modes, etc. have been given and presented in publications or appropriate meetings. A special consideration, within the theoretical effort, has been devoted to the study of plasma regimes that are important in devising future experiments of thermonuclear interest.

  16. Diagnosis of mildly relativistic electron velocity distributions by electron cyclotron emission in the Alcator C tokamak

    International Nuclear Information System (INIS)

    Mildly relativistic electron velocity distributions are diagnosed from measurements of the first few electron cyclotron emission harmonics in the Alcator C tokamak. The approach employs a vertical viewing chord through the center of the tokamak plasma terminating at a compact, high-performance viewing dump. The cyclotron emission spectra obtained in this way are dominated by frequency downshifts due to the relativistic mass increase, which discriminates the electrons by their total energy. In this way a one-to-one correspondence between the energy and the emission frequency is accomplished in the absence of harmonic superpositions. The distribution, described by f/sub p/, the line-averaged phase space density, and Λ, the anisotropy factor, is determined from the ratio of the optically thin harmonics or polarizations. Diagnosis of spectra in the second and the third harmonic range of frequencies obtained during lower hybrid heating, current drive, and low density ohmic discharges are carried out, using different methods depending on the degree of harmonic superposition present in the spectrum and the availability of more than one ratio measurement. Discussions of transient phenomena, the radiation temperature measurement from the optically thick first harmonic, and the measurements compared to the angular hard x-ray diagnostic results illuminate the capabilities of the vertically viewing electron cyclotron emission diagnostic

  17. Measurement of the current density profile in the Alcator C tokamak using lithium pellets

    International Nuclear Information System (INIS)

    High-speed lithium pellets have been injected into Alcator C tokamak plasmas in order to measure the internal magnetic field, and thus current density profiles. In the pellet ablation cloud, intense visible line radiation from the Li+ ion (λ∼5485 A, 1s2s 3S-1s2p 3P) is polarized due to the Zeeman effect, and measurement of the polarization angle yields the direction of the total local magnetic field. A ''snap shot'' of the q profile is obtained as the pellet penetrates from the edge into the center of the discharge, in a time of about 300 μs. The spatial resolution of the measurement is about 1 cm. At a toroidal field of BT=10 T, the emission in the unshifted π component of the Zeeman triplet is more than 80% polarized, and q profiles have been obtained. The pellets are perturbative (left-angle Δne right-angle/left-angle ne right-angle ∼1), but the total pellet penetration time is at least a factor of 1000 smaller than the classical skin time. It can thus be anticipated that the current density profile should not be perturbed significantly during the time of the measurement. With some relatively straightforward modifications and refinements, precision approaching 10% for the measurement of q profiles should be achievable. The technique appears viable, using Li, as long as the toroidal field is approx-gt 4 T

  18. Soft x-ray tomography diagnostic for the Alcator C tokamak

    International Nuclear Information System (INIS)

    A soft x-ray tomography diagnostic has been built and operated on the Alcator C tokamak with the use of an 80-channel array of detectors. The detector system consists of miniature PIN photodiodes which are located around the periphery of the plasma at one toroidal location (top and bottom ports) in order to image the poloidal cross section of the plasma's soft x-ray emissivity. The compact size and inexpensive cost of these detectors allow for the large number of views required to avoid any assumptions about plasma rotation, position, or symmetry in the reconstruction algorithm. The use of logarithmic amplifiers in the electronic circuitry makes it possible to record conveniently data from a wide range of plasma operating parameters. This diagnostic has been used to study plasma position and shape, magnetohydrodynamic (MHD) phenomena, and the effects of impurities. Data from a pellet-fueled discharge exhibiting large-scale MHD activity are presented. The system has recently been expanded to 128 detectors with the addition of an array on a side port in order to improve its coverage of the plasma and the resolution of the reconstructions

  19. A fast neutron spectrometer for D-D fusion neutron measurements at the Alcator C tokamak

    Science.gov (United States)

    Fisher, W. A.; Chen, S. H.; Gwinn, D.; Parker, R. R.

    1984-01-01

    A neutron spectrometer using a high pressure 3He ionization chamber has been designed and used to measure the neutron spectrum from an ohmically heated deuterium plasma. The resolution of the spectrometer at 2.45 MeV is determine to be 46 keV full width at half-maximum (fwhm). Particular attention has been paid to optimizing the detector shielding and collimation to reject thermal and epithermal neutrons scattered from the tokamak structure. As a result, measurements indicate that the ratio of the number of counts in the 2.45 MeV peak to the total number of detected neutron events is {1}/{67}. For the 8 μs amplifier time constant used, a count rate as high as 44 counts per second has been achieved in the thermonuclear peak. The observed spectra have been compared with calculated spectra using the MCNP Monte Carlo Neutral Particle Transport code and they show good agreement. There is little evidence of neutrons produced from photoneutron reactions or electrodisintegration. It has been possible to confirm that the shape of the thermonuclear peak is consistent with the Gaussian shape predicted and that the ion temperature as determined from the line width is consistent with other Alcator C ion temperature diagnostics, and follows the trends predicted by the theory of Doppler line broadening.

  20. Visible continuum measurements on the Alcator C Tokamak: Changes in particle transport during pellet fuelled discharges

    International Nuclear Information System (INIS)

    A spatially resolving visible light detector system is used to measure continuum radiation near 5360A on the Alcator C Tokamak. For the typically hot plasmas studied, the continuum emission is found to be dominated by bremsstrahlung radiation near this wavelength region. Accurate determinations of Z/sub eff/ are obtained from continuum measurements using independently determined temperature and density measurements. Density profiles during high density, clean pellet fueled discharges, are also determined and are used to study the changes in particle transport after injection. For discharges with sufficiently large pellet density increases, density profiles are found to become more peaked following the injection. In these cases, the profiles are found to remain peaked for the remainder of the discharge, or until a ''giant'' sawtooth or minor disruption abruptly returns the profiles to a flatter pre-pellet condition. Analysis of density profiles after pellet injection yields information about the radial diffusion and convection velocity of the plasma particles. The peakedness in the density profiles, observed after pellet injection, is attributable mostly to increases in inward convection. It is concluded that neoclassical fluxes are too small to account for these changes. 70 refs., 55 figs

  1. Energy confinement studies of lower hybrid current driven discharges in the Alcator C tokamak

    International Nuclear Information System (INIS)

    The energy confinement properties of purely RF-driven plasmas on Alcator C are being investigated by experimental measurements of the bulk electron and ion temperature profiles, and by numerical modelling of the lower hybrid wave propagation and thermal energy transport. Power balance studies are performed on plasmas with parameters n-bar/sub e/ = 3-7 x 1013 cm-3, B = 7-11 T, I/sub p/ = 100-200 kA, and q(a)> or =8, and with RF powers up to 1 MW at 4.6 GHz. The temperature mesurements from RF-driven discharges are compared with those from similar ohmic discharges (identical current and density). The gross energy confinement time, defined by tau/sub E/03/2 (Σ∫n/sub j/T/sub j/ dV)/P/sub i//sub n/, is lower in the RF-driven discharges than in the ohmic ones by a factor of 1.5 to 4, depending on the plasma conditions and RF power. While tau/sub E/ in ohmic discharges increases with density and is independent of the toroidal field, the confinement time in the RF-driven discharges decreases with RF power, is independent of density in the range n-bar/sub e/ = 3-7 x 1013cm-3, and increases with the toroidal magnetic field. The confinement degrades slightly with increasing current in both RF-driven and ohmic discharges. The code used to simulate these results employs a lower hybrid ray tracing package, a Fokker-Planck code for the evolution of the fast electron tail, and enhanced thermal transport models for auxiliary-heated plasmas. In the code simulations, more than 80% of the injected RF power is absorbed by electron Landau damping in the inner half of the plasma column, the remainder being dissipated by collisions near the plasma edge

  2. Lower hybrid experiments at the 1 MW level on Alcator C: heating and current drive

    International Nuclear Information System (INIS)

    Lower hybrid current drive and heating experiments have been carried out on the Alcator C tokamak at power levels up to 1.15 MW in the density range 1.0 x 1013 less than or equal to anti n/sub e/(cm-3) less than or equal to 1.0 x 1014. By launching waves with 670, 900 or 1120 phasing of adjacent waveguides, maximum flat-top current drive efficiencies of eta = R(m) x n(1014cm-3)I(MA)/P(MW) = 0.12 at B = 10 tesla, and eta approx. = 0.08 at B = 8 tesla were obtained with molybdenum limiters. With graphite, or silicon-carbide coated graphite limiters the efficiencies were 30 to 40% lower. Current ramping experiments have also been carried out at densities up to anti n approx. = 6 x 1013cm-3. By phasing the adjacent waveguides at 1800, heating experiments were performed in the density range 8 x 1013 less than or equal to anti n(cm-3) less than or equal to 2 x 1014 in both hydrogen and deuterium plasmas. This range of densities corresponds to the electron Landau heating mode. Using molybdenum limiters, typical heating rates of the order of eta/sub H/ = delta Σ n/sub j/T/sub j//P/sub rf/ approx. = 10 eV/kW 1013cm-3 were obtained, whereas with the SiC coated graphite limiters heating rates up to eta/sub H/ approx. = 22 were achieved. Measurements of soft and hard x-rays indicate the presence of substantial electron tails in both the current drive and the electron heating regimes. A combined transport, ray-tracing and Fokker-Planck code is used to analyze and model both the heating and the current drive results

  3. Lower hybrid current drive experiments on the MIT Alcator C and Versator II tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Knowlton, S.; McDermott, S.; Porkolab, M.; Takase, Y.; Texter, S.; Bonoli, P.; Fiore, C.; McCool, S.; Mayberry, M.; Chen, K.I.

    1985-08-01

    Energy confinement studies in lower hybrid RF driven discharges at 4.6 GHz have been carried out on the Alcator C tokamak. The electron temperature profile is measured by a five point Thomson scattering system and the ion temperature by charge-exchange analysis. The energy content of the bulk plasma is found to be similar for RF-driven and ohmic discharges of identical current and density. In the parameter range anti n/sub e/ = 3 - 7 x 10/sup 13/ cm/sup -3/, B = 7 - 11 T, I/sub p/ = 100 - 200 kA, q (a) > 8, the RF power needed to sustain the discharge is significantly greater than the ohmic power required to maintain a similar plasma. The gross energy confinement time is lower in the RF-driven discharges than in the ohmic ones by a factor of 1.5 to 4, depending on plasma conditions. The frequency scaling of the density limit for current drive is reported from the Versator II tokamak. The steady-state current drive density limit of anti n/sub e/ = 6 x 10/sup 12/ cm/sup -3/ at 800 MHz. has been raised to a density of at least anti n/sub e/ = 1.0 x 10/sup 13/ cm/sup -3/ at the same toroidal field by operations at a frequency of 2.45 GHz. Superthermal electron effects during RF injection are observed up to a density of anti n/sub e/ = 2.5 x 10/sup 13/ cm/sup -3/.

  4. Study of parametric instabilities during the Alcator C lower hybrid wave heating experiments

    International Nuclear Information System (INIS)

    Parametric excitation of ion-cyclotron quasi-modes (ω/sub R/ approx. = nω/sub ci/) and ion-sound quasi-modes (ω/sub R/ approx. = k/sub parallel to/v/sub ti/) during lower hybrid wave heating of tokamak plasmas have been studied in detail. Such instabilities may significantly modify the incident wavenumber spectrum near the plasma edge. Convective losses for these instabilities are high if well-defined resonance cones exist, but they are significantly reduced if the resonance cones spread and fill the plasma volume (or some region of it). These instabilities preferentially excite lower hybrid waves with larger values of n/sub parallel to/ than themselves possess, and the new waves tend to be absorbed near the outer layers of the plasma. Parametric instabilities during lower hybrid heating of Alcator C plasmas have been investigated using rf probes (to study tilde phi and tilde n/sub i/) and CO2 scattering technique (to study tilde n/sub e/). At lower densities (anti n/sub e/ less than or equal to 0.5 x 1014cm-3) where waves observed in the plasma interior using CO2 scattering appear to be localized, parametric decay is very weak. Both ion-sound and ion-cyclotron parametric decay processes have been observed at higher densities (anti n greater than or equal to 1.5 x 1014cm-3) where waves appear to be unlocalized. Finally, at still higher densities (anti n /sub e/ greater than or equal to 2 x 104cm-3) pump depletion has been observed. Above these densities heating and current drive efficiencies are expected to degrade significantly

  5. Impurity generation during intense lower hybrid heating experiments on the Alcator C tokamak

    Science.gov (United States)

    Marmar, E.; Foord, M.; Labombard, B.; Lipschultz, B.; Moreno, J.; Rice, J.; Terry, J.; Lloyd, B.; Porkolab, M.; Schuss, J.; Takase, Y.; Texter, S.; Fiore, C.; Gandy, R.; Granetz, R.; Greenwald, M.; Gwinn, D.; McCool, S.; Pappas, D.; Parker, R. R.; Pribyl, P.; Watterson, R.; Wolfe, S. M.

    1984-05-01

    Experiments are underway on the Alcator C tokamak with over 1 MW of RF power injected into the plasma at a frequency of 4.6 GHz to study both heating and current drive effects. During these studies, impurity generation from limiter structures has been observed. The RF induced impurity influx is a strongly nonlinear function of net injected power. For PRF < 500 kW, only small effects are seen. As PRF approaches 1 MW, however, sharp increases in impurity influxes and Zeff are observed. Three different limiter materials have been used during these studies: molybdenum, graphite, and silicon-carbide coated graphite. In each case, the materials of the limiter structure are seen to dominate the increased impurity influx. In a typical case, with P RF = 1.0 MW, overlinene = 1.3 × 10 14cm-3, and the SiC coated limiters, Zeff is seen to increase from 1.5 before the RF pulse to about 4 during the heating. At the same time, central Te increases from 2000 to 3000 eV and central Ti from 1200 to 1800 eV. Similar effects are seen in both H 2 and D 2 working gas discharges. The contribution to impurity generation of nonthermal electrons, which are produced by the RF, is under investigation. Changes in edge plasma temperature and density, as well as the possibility that the particle transport is affected by the RF, are also being examined. Results of the experiments with the three different limiter materials are compared, and contributions of impurity radiation to the overall power balance are estimated.

  6. Fast wave ion cyclotron resonance heating experiments on the Alcator C tokamak

    International Nuclear Information System (INIS)

    Minority regime fast wave ICRF heating experiments have been conducted on the Alcator C tokamak at rf power levels sufficient to produce significant changes in plasma properties, and in particular to investigate the scaling to high density of the rf heating efficiency. Up to 450 kW of rf power at frequency f = 180 MHz, was injected into plasmas composed of deuterium majority and hydrogen minority ion species at magnetic field B0 = 12 T, density 0.8 ≤ /bar n/sub e// ≤ 5 /times/ 1020 m-3, ion temperature T/sub D/(0) /approximately/ 1 keV, electron temperature T/sub e/(0) /approximately/ 1.5--2.5 keV, and minority concentration 0.25 /approx lt/ /eta/sub H// ≤ 8%. Deuterium heating ΔT/sub D/(0) = 400 eV was observed at /bar n/sub e// = 1 /times/ 1020 m-3, with smaller temperature increases at higher density. However, there was no significant change in electron temperature and the minority temperatures were insufficient to account for the launched rf power. Minority concentration scans indicated most efficient deuterium heating at the lowest possible concentration, in apparent contradiction with theory. Incremental heating /tau/sub inc// /equivalent to/ ΔW/ΔP up to 5 ms was independent of density, in spite of theoretical predictions of favorable density scaling of rf absorption and in stark contrast to Ohmic confinement times /tau/sub E// /equivalent to/ W/P. After accounting for mode conversion and minority losses due to toroidal field ripple, unconfined orbits, asymmetric drag, neoclassical and sawtooth transport, and charge-exchange, it was found that the losses as well as the net power deposition on deuterium do scale very favorably with density. Nevertheless, when the net rf and Ohmic powers deposited on deuterium are compared, they are found to be equally efficient at heating the deuterium. 139 refs

  7. Effects of thermal expansion of the crystal lattice on x-ray crystal spectrometers used for fusion research

    International Nuclear Information System (INIS)

    X-ray imaging crystal spectrometers with high spectral and spatial resolution are currently being used on magnetically confined fusion devices to infer the time history profiles of ion and electron temperatures as well as plasma flow velocities. The absolute measurement of flow velocities is important for optimizing various discharge scenarios and evaluating the radial electric field in tokamak and stellarator plasmas. Recent studies indicate that the crystal temperature must be kept constant to within a fraction of a degree to avoid changes of the interplanar 2d-spacing by thermal expansion that cause changes in the Bragg angle, which could be misinterpreted as Doppler shifts. For the instrumental parameters of the x-ray crystal spectrometer on Alcator C-Mod, where those thermal effects were investigated, a change of the crystal temperature by 1 °C causes a change of the lattice spacing of the order of Δd = 1 × 10−5 Å introducing a fictitious velocity drift of the order of ∼3 km s−1. This effect must be considered for x-ray imaging crystals spectrometers installed on LHD, KSTAR, EAST, J-TEXT, NSTX and, in the future, W7-X and ITER. (paper)

  8. Study of electron temperature evolution during sawtoothing and pellet injection using thermal electron cyclotron emission in the Alcator C tokamak

    International Nuclear Information System (INIS)

    A study of the electron temperature evolution has been performed using thermal electron cyclotron emission. A six channel far infrared polychromator was used to monitor the radiation eminating from six radial locations. The time resolution was <3 μs. Three events were studied, the sawtooth disruption, propagation of the sawtooth generated heatpulse and the electron temperature response to pellet injection. The sawtooth disruption in Alcator takes place in 20 to 50 μs, the energy mixing radius is approx. 8 cm or a/2. It is shown that this is inconsistent with single resonant surface Kadomtsev reconnection. Various forms of scalings for the sawtooth period and amplitude were compared. The electron heatpulse propagation has been used to estimate chi e(the electron thermal diffusivity). The fast temperature relaxation observed during pellet injection has also been studied. Electron temperature profile reconstructions have shown that the profile shape can recover to its pre-injection form in a time scale of 200 μs to 3 ms depending on pellet size

  9. Plasma X-ray emission in the 20-500 keV range during lower hybrid current drive on Alcator

    International Nuclear Information System (INIS)

    An array of eight 1'' x 3'' NaI scintillators has been used to collect plasma hard x-ray spectra (E/sub γ/>20 keV) emitted perpendicular to the magnetic axis during lower hybrid current drive on Alcator. The spectra exhibit a tail extending out to at least 300 keV and the profiles are generally peaked. These results show that the slope of the x-ray spectra increases with increasing plasma radius. Equivalently, the emission profiles tend to broaden with increasing photon energy. Also, the x-ray spectra slope increases at each radial location as the relative phasing of adjacent waveguides in the grill antenna is decreased. Preliminary results also suggest that the x-ray spectra tend to flatten and that the emission profiles tend to peak up with decreasing plasma density or increasing magnetic field. In addition, the initial results of an array for measuring the high energy x-ray emission from Alcator as a function of the emission angle relative to the magnetic axis are presented

  10. Impact of the Pedestal on Global Performance and Confinement Scalings in I-mode

    Science.gov (United States)

    Walk, John; Hughes, Jerry; Hubbard, Amanda; Whyte, Dennis; White, Anne; Alcator C-Mod Team

    2015-11-01

    The I-mode is a novel high-confinement regime pioneered on Alcator C-Mod, notable for its strong temperature pedestal without the accompanying density pedestal found in conventional H-modes. This separation in transport channels gives the desired improved energy confinement while maintaining low particle confinement, avoiding excessive impurity accumulation. Moreover, I-mode operation is naturally free of deleterious Edge-Localized Modes (ELMs). Recent experiments on Alcator C-Mod have characterized the pedestal structure in I-mode. The impact of the pedestal response (particularly to fueling and heating power) and core profile stiffness on global performance and confinement have demonstrated confinement metrics competitive with H-mode operation on Alcator C-Mod, and consistent with concepts for I-mode access & operation on ITER. Following the practice of the ITER89 and ITER98 scaling laws for L- and H-mode energy confinement, an initial, illustrative attempt at an I-mode confinement scaling has also been developed. The initial characterization from C-Mod data is consistent with the observed pedestal properties in I-mode, particularly the weak degradation of energy confinement with heating power, and comparatively strong positive response to fueling and increased magnetic field. Supported by U.S. Department of Energy award DE-FC02-99ER54512, using Alcator C-Mod, a DOE Office of Science User Facility.

  11. 2012 Joint Research Target (JRT) Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Team, JRT

    2012-09-30

    The report summarizes: [1] Diagnostic upgrades and analysis improvements that support the JRT; [2] Descriptions of new experiments and a brief summary of findings; [3] New analysis of previous experiments; [4] Plans for further data analysis and recommendations for further work; [5] Scientific publications that are derived from or contributed directly to the JRT. The report is organized as follows: Section 1: Describes inter-machine comparisons that were facilitated by the JRT focus. Similarities and differences found on the different facilities are outlined, and plans for additional analysis of data and supporting simulations are described.Section 2: Reviews diagnostic development, experiments and results from C-Mod. C-Mod dedicated 13.1 run days to the JRT divided among 10 experimental proposals. These were organized into three general thrust areas that represent distinct experimental approaches to realizing the regimes called for in the JRT description. Initial comparisons with linear and nonlinear simulation have been carried out for these experiments, and plans for an extensive campaign of analysis have been outlined. Section 3: Reviews results from DIII-D including new experiments, detailed comparisons of simulations to previously collected data and connections between the new work and past research. Four experimental days were dedicated to the JRT in 2012. These included studies of L-modes, H-modes and QH-modes. Section 4: Summarizes new analysis of data collected before the NSTX shutdown. The work focuses on the roles of low and high-k turbulence; collisionality scans and impurity particle transport.

  12. 2012 Joint Research Target (JRT) Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Team, JRT

    2012-09-30

    The report summarizes: [1] Diagnostic upgrades and analysis improvements that support the JRT; [2] Descriptions of new experiments and a brief summary of our findings; [3] New analysis of previous experiments; [4] Plans for further data analysis and recommendations for further work; [5] Scientific publications that are derived from or contributed directly to the JRT. The report is organized as follows: Section 1: Describes inter-machine comparisons that were facilitated by the JRT focus. Similarities and differences found on the different facilities are outlined and plans for additional analysis of data and supporting simulations are described.Section 2: Reviews diagnostic development, experiments and results from C-Mod. C-Mod dedicated 13.1 run days to the JRT divided among 10 experimental proposals. These were organized into three general thrust areas that represent distinct experimental approaches to realizing the regimes called for in the JRT description. Initial comparisons with linear and nonlinear simulation have been carried out for these experiments and plans for an extensive campaign of analysis has been outlined. Section 3: Reviews results from DIII-D including new experiments, detailed comparisons of simulations to previously collected data and connections between the new work and past research. Four experimental days were dedicated to the JRT in 2012. These included studies of L-modes, H-modes and QH-modes. Section 4: Summarizes new analysis of data collected before the NSTX shutdown. The work focuses on the roles of low and high-k turbulence; collisionality scans and impurity particle transport.

  13. Nonlinearly Driven Second Harmonics of Alfven Cascades

    International Nuclear Information System (INIS)

    In recent experiments on Alcator C-Mod, measurements of density fluctuations with Phase Contrast Imaging through the plasma core show a second harmonic of the basic Alfven Cascade (AC) signal. The present work describes the perturbation at the second harmonic as a nonlinear sideband produced by the Alfven Cascade eigenmode via quadratic terms in the MHD equations. (author)

  14. Massachusetts Institute of Technology, Plasma Fusion Center, technical research programs

    Energy Technology Data Exchange (ETDEWEB)

    1982-02-01

    Research programs have produced significant results on four fronts: (1) the basic physics of high-temperature fusion plasmas (plasma theory, RF heating, development of advanced diagnostics and small-scale experiments on the Versator tokamak and Constance mirror devices); (2) major confinement results on the Alcator A and C tokamaks, including pioneering investigations of the equilibrium, stability, transport and radiation properties of fusion plasmas at high densities, temperatures and magnetic fields; (3) development of a new and innovative design for axisymmetric tandem mirrors with inboard thermal barriers, with initial operation of the TARA tandem mirror experimental facility scheduled for 1983; and (4) a broadly based program of fusion technology and engineering development that addresses problems in several critical subsystem areas (e.g., magnet systems, superconducting materials development, environmental and safety studies, advanced gyrotron development for RF heating, preconceptual design studies of torsatrons and stellarators, and advanced tokamak design and reactor studies).

  15. Massachusetts Institute of Technology, Plasma Fusion Center, technical research programs

    International Nuclear Information System (INIS)

    Research programs have produced significant results on four fronts: (1) the basic physics of high-temperature fusion plasmas (plasma theory, RF heating, development of advanced diagnostics and small-scale experiments on the Versator tokamak and Constance mirror devices); (2) major confinement results on the Alcator A and C tokamaks, including pioneering investigations of the equilibrium, stability, transport and radiation properties of fusion plasmas at high densities, temperatures and magnetic fields; (3) development of a new and innovative design for axisymmetric tandem mirrors with inboard thermal barriers, with initial operation of the TARA tandem mirror experimental facility scheduled for 1983; and (4) a broadly based program of fusion technology and engineering development that addresses problems in several critical subsystem areas

  16. Research

    Science.gov (United States)

    Mathematics Teaching, 1973

    1973-01-01

    Implications for teachers from Piagetian-oriented piagetian-oriented research on problem solving reported in an article by Eleanor Duckworth are presented. Edward de Bono's Children Solve Problems,'' a collection of examples, is also discussed. (MS)

  17. Improved Controls for Fusion RF Systems. Final technical report

    International Nuclear Information System (INIS)

    We have addressed the specific requirements for the integrated systems controlling an array of klystrons used for Lower Hybrid Current Drive (LHCD). The immediate goal for our design was to modernize the transmitter protection system (TPS) for LHCD on the Alcator C-Mod tokamak at the MIT Plasma Science and Fusion Center (MIT-PSFC). Working with the Alcator C-Mod team, we have upgraded the design of these controls to retrofit for improvements in performance and safety, as well as to facilitate the upcoming expansion from 12 to 16 klystrons. The longer range goals to generalize the designs in such a way that they will be of benefit to other programs within the international fusion effort was met by designing a system which was flexible enough to address all the MIT system requirements, and modular enough to adapt to a large variety of other requirements with minimal reconfiguration

  18. Improved Controls for Fusion RF Systems. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Jeffrey A. [Rockfield Research Inc., Las Vegas, NV (United States)

    2011-11-08

    We have addressed the specific requirements for the integrated systems controlling an array of klystrons used for Lower Hybrid Current Drive (LHCD). The immediate goal for our design was to modernize the transmitter protection system (TPS) for LHCD on the Alcator C-Mod tokamak at the MIT Plasma Science and Fusion Center (MIT-PSFC). Working with the Alcator C-Mod team, we have upgraded the design of these controls to retrofit for improvements in performance and safety, as well as to facilitate the upcoming expansion from 12 to 16 klystrons. The longer range goals to generalize the designs in such a way that they will be of benefit to other programs within the international fusion effort was met by designing a system which was flexible enough to address all the MIT system requirements, and modular enough to adapt to a large variety of other requirements with minimal reconfiguration.

  19. Turbulence at the transition to the high density H-mode in Wendelstein 7-AS plasmas

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Baumel, S.;

    2003-01-01

    Recently a new improved confinement regime was found in the Wendelstein 7-AS (W7-AS) stellarator (Renner H. et al 1989 Plasma Phys. Control. Fusion 31 1579). The discovery of this high density high confinement mode (HDH-mode) was facilitated by the installation of divertor modules. In this paper......-mode (EDA H-mode) found in the Alcator C-Mod tokamak and the HDH-mode in W7-AS is carried out....

  20. Researching research

    DEFF Research Database (Denmark)

    Pais, Alexandre; Valero, Paola

    2012-01-01

    We discuss contemporary theories in mathematics education in order to do research on research. Our strategy consists of analysing discursively and ideologically recent key publications addressing the role of theory in mathematics education research. We examine how the field fabricates its object...... of research by deploying Foucault’s notion of bio-politics - mainly to address the object “learning” - and Žižek’s ideology critique - to address the object “mathematics”. These theories, which have already been used in the field to research teaching and learning, have a great potential to contribute...... to a reflexivity of research on its discourses and effects. Furthermore, they enable us to present a clear distinction between what has been called the sociopolitical turn in mathematics education research and what we call a positioning of mathematics education (research) practices in the Political....

  1. Disruption mitigation using high pressure gas jets. Final report

    International Nuclear Information System (INIS)

    The goal of this research is to establish credible disruption mitigation scenarios based on the technique of massive gas injection. Disruption mitigation seeks to minimize or eliminate damage to internal components that can occur due to the rapid dissipation of thermal and magnetic energy during a tokamak disruption. In particular, the focus of present research is extrapolating mitigation techniques to burning plasma experiments such as ITER, where disruption-caused damage poses a serious threat to the lifetime of internal vessel components. A majority of effort has focused on national and international collaborative research with large tokamaks: DIII-D, Alcator C-Mod, JET, and ASDEX Upgrade. The research was oriented towards empirical trials of gas-jet mitigation on several tokamaks, with the goal of developing and applying cohesive models to the data across devices. Disruption mitigation using gas jet injection has proven to be a viable candidate for avoiding or minimizing damage to internal components in burning plasma experiments like ITER. The physics understanding is progress towards a technological design for the required gas injection system in ITER.

  2. Axisymmetric control in tokamaks

    International Nuclear Information System (INIS)

    Vertically elongated tokamak plasmas are intrinsically susceptible to vertical axisymmetric instabilities as a result of the quadrupole field which must be applied to produce the elongation. The present work analyzes the axisymmetric control necessary to stabilize elongated equilibria, with special application to the Alcator C-MOD tokamak. A rigid current-conserving filamentary plasma model is applied to Alcator C-MOD stability analysis, and limitations of the model are addressed. A more physically accurate nonrigid plasma model is developed using a perturbed equilibrium approach to estimate linearized plasma response to conductor current variations. This model includes novel flux conservation and vacuum vessel stabilization effects. It is found that the nonrigid model predicts significantly higher growth rates than predicted by the rigid model applied to the same equilibria. The nonrigid model is then applied to active control system design. Multivariable pole placement techniques are used to determine performance optimized control laws. Formalisms are developed for implementing and improving nominal feedback laws using the C-MOD digital-analog hybrid control system architecture. A proportional-derivative output observer which does not require solution of the nonlinear Ricatti equation is developed to help accomplish this implementation. The nonrigid flux conserving perturbed equilibrium plasma model indicates that equilibria with separatrix elongation of at least sep = 1.85 can be stabilized robustly with the present control architecture and conductor/sensor configuration

  3. Plasma-Surface Interactions and RF Antennas

    Science.gov (United States)

    Jenkins, Thomas; Smithe, D. N.; Beckwith, K.; Davidson, B. D.; Kruger, S. E.; Pankin, A. Y.; Roark, C. M.

    2015-11-01

    Implementation of recently developed finite-difference time-domain (FDTD) modeling techniques on high-performance computing platforms allows RF power flow, and antenna near- and far-field behavior, to be studied in realistic experimental ion-cyclotron resonance heating scenarios at previously inaccessible levels of resolution. We present results and 3D animations of high-performance (10k-100k core) FDTD simulations of Alcator C-Mod's field-aligned ICRF antenna on the Titan supercomputer, considering (a) the physics of slow wave excitation in the immediate vicinity of the antenna hardware and in the scrape-off layer for various edge densities, and (b) sputtering and impurity production, as driven by self-consistent sheath potentials at antenna surfaces. Related research efforts in low-temperature plasma modeling, including the use of proper orthogonal decomposition methods for PIC/fluid modeling and the development of plasma chemistry tools (e.g. a robust and flexible reaction database, principal path reduction analysis capabilities, and improved visualization options), will also be summarized. Supported by U.S. DoE SBIR Phase I/II Award DE-SC0009501 and ALCC/OLCF.

  4. Development of a spatially resolving x-ray crystal spectrometer for measurement of ion-temperature (T(i)) and rotation-velocity (v) profiles in ITER.

    Science.gov (United States)

    Hill, K W; Bitter, M; Delgado-Aparicio, L; Johnson, D; Feder, R; Beiersdorfer, P; Dunn, J; Morris, K; Wang, E; Reinke, M; Podpaly, Y; Rice, J E; Barnsley, R; O'Mullane, M; Lee, S G

    2010-10-01

    Imaging x-ray crystal spectrometer (XCS) arrays are being developed as a US-ITER activity for Doppler measurement of T(i) and v profiles of impurities (W, Kr, and Fe) with ∼7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a prototype instrument on Alcator C-Mod, uses a spherically bent crystal and 2D x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure T(i) and both poloidal and toroidal rotation velocity profiles. The measurement of many spatial chords permits tomographic inversion for the inference of local parameters. The instrument design, predictions of performance, and results from C-Mod are presented.

  5. Development of a Spatially Resolving X-Ray Crystal Spectrometer (XCS) for Measurement of Ion-Temperature (Ti) and Rotation-Velocity (v) Profiles in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K W; Delgado-Aprico, L; Johnson, D; Feder, R; Beiersdorfer,; Dunn, J; Morris, K; Wang, E; Reinke, M; Podpaly, Y; Rice, J E; Barnsley, R; O' Mullane, M; Lee, S G

    2010-05-21

    Imaging XCS arrays are being developed as a US-ITER activity for Doppler measurement of Ti and v profiles of impurities (W, Kr, Fe) with ~7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a PPPL-MIT instrument on Alcator C-Mod, uses a spherically bent crystal and 2d x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure Ti and both poloidal and toroidal rotation velocity profiles. Measurement of many spatial chords permits tomographic inversion for inference of local parameters. The instrument design, predictions of performance, and results from C-Mod will be presented.

  6. Development of a spatially resolving x-ray crystal spectrometer for measurement of ion-temperature (T{sub i}) and rotation-velocity (v) profiles in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Johnson, D.; Feder, R. [Princeton Plasma Physics Laboratory, P.O. Box 451 MS 15, Princeton, New Jersey 08543 (United States); Beiersdorfer, P.; Dunn, J.; Morris, K.; Wang, E. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Reinke, M.; Podpaly, Y.; Rice, J. E. [MIT Plasma Science and Fusion Center, 190 Albany Street, Cambridge, Massachusetts 02139 (United States); Barnsley, R. [ITER Cadarache JWS, Cadarache Centre, 13108 St Paul-Les-Durance (France); O' Mullane, M. [Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Lee, S. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)

    2010-10-15

    Imaging x-ray crystal spectrometer (XCS) arrays are being developed as a US-ITER activity for Doppler measurement of T{sub i} and v profiles of impurities (W, Kr, and Fe) with {approx}7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a prototype instrument on Alcator C-Mod, uses a spherically bent crystal and 2D x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure T{sub i} and both poloidal and toroidal rotation velocity profiles. The measurement of many spatial chords permits tomographic inversion for the inference of local parameters. The instrument design, predictions of performance, and results from C-Mod are presented.

  7. Development of a spatially resolving x-ray crystal spectrometer for measurement of ion-temperature (T[sub i]) and rotation-velocity (v) profiles in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Johnson, D.; Feder, R.; Beiersdorfer, P.; Dunn, J.; Morris, K.; Wang, E.; Reinke, M.; Podpaly, Y.; Rice, J. E.; Barnsley, R.; O’Mullane, M.; Lee, S. G.

    2010-01-01

    Imaging x-ray crystal spectrometer XCS arrays are being developed as a US-ITER activity for Doppler measurement of Ti and v profiles of impurities (W, Kr, and Fe) with ~ 7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a prototype instrument on Alcator C-Mod, uses a spherically bent crystal and 2D x-ray detectors to achieve high spectral resolving power (E / dE > 6000) horizontally and spatial imaging vertically. Two arrays will measure Ti and both poloidal and toroidal rotation velocity profiles. The measurement of many spatial chords permits tomographic inversion for the inference of local parameters. The instrument design, predictions of performance, and results from C-Mod are presented.

  8. Free-boundary toroidal Alfvén eigenmodes

    Science.gov (United States)

    Chen, Eugene Y.; Berk, H. L.; Breizman, B.; Zheng, L. J.

    2011-05-01

    A numerical study is presented for the n = 1 free-boundary toroidal Alfvén eigenmodes (TAE) in tokamaks, which shows that there is considerable sensitivity of n = 1 modes to the position of the conducting wall. An additional branch of the TAE is shown to emerge from the upper continuum as the ratio of conducting wall radius to plasma radius increases. Such phenomena arise in plasma equilibria with both circular and shaped cross sections, where the shaped profile studied here is similar to that found in Alcator C-Mod.

  9. Improved L-mode discharges using ion cyclotron resonance frequency heating on Tore Supra

    International Nuclear Information System (INIS)

    Recent results of ion cyclotron minority heating have been obtained with an improved L-mode confinement, close to ELMy H-mode prediction, at relatively high density. The confinement exceeds the standard L-mode by a factor up to 1.7. The improvement of the confinement is observed in both electron and ion channels with reduction of heat diffusivities. This improved confinement regime presents some features similar to the results previously observed in many tokamaks: ALCATOR C-MOD [1] with ICRH, and radiation improved confinement (RI) mode with neutral beam injection in TEXTOR [2], TFTR [3], DIII-D [4

  10. Objectives and Layout of a High-Resolution X-ray Imaging Crystal Spectrometer for the Large Helical Device (LHD)

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Gates, D; Monticello, D; Neilson, H; Reiman, A; Roquemore, A L; Morita, S; Goto, M; Yamada, H

    2010-07-29

    A high-resolution X-ray imaging crystal spectrometer, whose concept was tested on NSTX and Alcator C-Mod, is being designed for LHD. This instrument will record spatially resolved spectra of helium-like Ar16+ and provide ion temperature profiles with spatial and temporal resolutions of < 2 cm and ≥ 10 ms. The stellarator equilibrium reconstruction codes, STELLOPT and PIES, will be used for the tomographic inversion of the spectral data. The spectrometer layout and instrumental features are largely determined by the magnetic field structure of LHD.

  11. Researcher / Researched: Repositioning Research Paradigms

    Science.gov (United States)

    Meerwald, Agnes May Lin

    2013-01-01

    "Researcher / Researched" calls for a complementary research methodology by proposing autoethnography as both a method and text that crosses the boundaries of conventional and alternative methodologies in higher education. Autoethnography rearticulates the researcher / researched positions by blurring the boundary between them. This…

  12. The Role of Atomic and Molecular Processes in Magnetic Fusion Plasmas

    International Nuclear Information System (INIS)

    Plasma edge physics (plasmas with temperatures in the 1 to 100 eV range, near solid surfaces) has become a key issue in controlled nuclear fusion research. As for the physics of the fully ionized hot plasma core, appropriate dimensionless parameters have been identified: present fusion research acts like wind-channel experiments on downsized models, with respect to future fusion reactors. This is not longer possible for the plasma edge region due to dominant effects from atomic and surface processes. Integrated computational models comprising the physics of the plasma flow near boundaries, the atomic and molecular processes and the particle-surface interactions are the only tool to evaluate present experimental results (LHD, JT60, Tore Supra, JET,...) with respect to their relevance for future fusion power experiments (ITER) or a reactor.In particular proton and electron collisions with the hydrogenic molecules H2, O2, T2, DT, and their ions, play a key role in cooling and attenuating the magnetically confined plasma, before it hits exposed target surfaces. The surface released molecules travel in a bath of electrons and hydrogenic ions, with plasma temperatures (in the relevant region) in the 1 to 20 eV range, and typical (plasma) scale lengths are in the 1 to 10 cm range.Sample calculations with current fusion plasma edge codes, as e.g. used by the international design team for the ITER prototypical fusion reactor, applied to the tokamak with the highest divertor collisionality today (Alcator-C-Mod), are used to demonstrate these issues

  13. High confinement and high density with stationary plasma energy and strong edge radiation cooling in the upgraded Torus Experiment for Technology Oriented Research (TEXTOR-94)

    Energy Technology Data Exchange (ETDEWEB)

    Messiaen, A.M.; Ongena, J.; Unterberg, B.; Boedo, J.; Fuchs, G.; Jaspers, R.; Konen, L.; Koslowski, H.R.; Mank, G.; Rapp, J.; Samm, U.; Vandenplas, P.E.; Van Oost, G.; Van Wassenhove, G.; Waidmann, G.; Weynants, R.R.; Wolf, G.H.; Bertschinger, G.; Bonheure, G.; Brix, M.; Dumortier, P.; Durodie, F.; Finken, K.H.; Giesen, B.; Hillis, D.; Hutteman, P.; Koch, R.; Kramer-Flecken, A.; Lyssoivan, A.; Mertens, P.; Pospieszczyk, A.; Post-Zwicker, A.; Sauer, M.; Schweer, B.; Schwelberger, J.; Telesca, G.; Tokar, M.Z.; Uhlemann, R.; Vervier, M.; Winter, J. [Laboratoire de Physique des Plasmas, Laboratorium voor Plasmafysica, Association EURATOM-Belgian State, Ecole Royale Militaire-B-1000 Brussels, Koninklijke Militaire School (Belgium)]|[Institut fuer Plasmaphysik, Forschungszentrum Juelich GmbH Association Euratom-KFA, D-52425 Juelich (Germany)]|[Fusion Energy Research Program, Mechanical Engineering Division, University of California at San Diego, La Jolla, California 92093 (United States)]|[FOM Instituut voor Plasmafysica Rijnhuizen Associatie FOM-EURATOM, Nieuwegein (The Netherlands)]|[Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    1997-05-01

    An overview of the results obtained so far for the radiative I-mode regime on the upgraded Torus Experiment for Technology Oriented Research (TEXTOR-94) [{ital Proceedings of the 16th IEEE Symposium on Fusion Engineering} (Institute of Electrical and Electronics Engineers, Piscataway, NJ, 1995), Vol. 1, p. 470] is given. This regime is obtained under quasistationary conditions with edge neon seeding in a pumped limiter tokamak with circular cross section. It combines high confinement and high {beta} (up to a normalized beta, {beta}{sub n}=2) with low edge q values (down to q{sub a}=2.8) and high density even above the Greenwald limit together with dominant edge radiative heat exhaust, and therefore shows promise for the future of fusion research. Bulk and edge properties of these discharges are described, and a detailed account is given of the energy and particle confinement and their scaling. Energy confinement scales linearly with density as for the nonsaturated Ohmic Neo-Alcator scaling, but the usual degradation with total power remains. No deleterious effects of the neon seeding on fusion reactivity and plasma stability have been observed. {copyright} {ital 1997 American Institute of Physics.}

  14. Research on agricultural research

    OpenAIRE

    Renborg, Ulf

    2010-01-01

    A Cobb-Douglas type production function is estimated for the Swedish agricultural sector over the period 1944/45 - 1986/87. Total production of the sector is the dependent variable. Public research and advisory services are introduced as independent variables together with labour, land, variable capital and inputs bought from other sectors and a yield variable. Research is introduced with lags from 6 to 24 years from research inputs to effects on the total sector production. Research lags of ...

  15. 2013 Nuclear Fusion Prize Acceptance Speech 2013 Nuclear Fusion Prize Acceptance Speech

    Science.gov (United States)

    Whyte, D.

    2015-01-01

    I would like to express gratitude to the IAEA, the journal Nuclear Fusion and its board for this acknowledgement of work carried out at the MIT Alcator C-Mod tokamak. I must begin by making it clear that this is in no way an award to an individual. The experiments, data analysis and paper were a true collaborative effort from the C-Mod team. It is a honor to work with them and to accept the award on their behalf. I would also like to thank the US Department of Energy for their support in funding this research. The paper describes the exploration of the 'improved' confinement regime dubbed 'I-mode'. The distinguishing feature of this operational mode is a robust boundary pedestal in temperature with the somewhat surprising lack of any form of density pedestal. Thus the regime exhibits an enhanced energy confinement similar to H-mode, roughly double of L-mode at fixed input power, yet has global fuel and impurity particle transport of L-mode. These features are intriguing from a scientific and practical point of view. On the science side it is extremely useful to obtain such a clear demarcation between the energy and particle transport. For example, soon after its discovery, the I-mode was used to extract the observation that the edge T pedestal is the strongest determinant for intrinsic rotation in work by John Rice, Pat Diamond and colleagues. Recent results regarding core transport by Anne White, Nate Howard and colleagues show that I-mode has intriguing properties with respect to core response of fluctuations and profile stiffness. Mike Churchill's recent Ph. D study on C-Mod shows that I-mode exhibits no strong poloidal impurity asymmetry, unlike H-mode. The I-mode posed an interesting test for the peeling-ballooning-KBM model of the pedestal, the subject of the 2014 Nuclear Fusion award of Phil Snyder, and was examined by John Walk and Jerry Hughes showing that in fact the lack of the density pedestal pushed the I-mode far away from the P-B limit, and thus the

  16. Research News

    Science.gov (United States)

    Research News - National Multiple Sclerosis Society Skip to navigation Skip to content Menu Navigation National Multiple Sclerosis ... Email Home Research Research News & Progress Research News Research News Share Smaller Text Larger Text Print Read ...

  17. Malaria Research

    Science.gov (United States)

    ... Content Marketing Share this: Main Content Area Malaria Research NIAID Role in Malaria Research Basic Biology Prevention ... Labs​ Malaria Research Program Services for Researchers Featured Research Ancient Immune Mechanism Identified That Controls Malaria in ...

  18. ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

    Science.gov (United States)

    Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

    2012-03-01

    ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from

  19. Entangled research(ers)

    DEFF Research Database (Denmark)

    Brøgger, Katja; Staunæs, Dorthe

    This paper takes up the challenges of analyzing how empirical knowledge is created when the research(ers) are always already “thrown into the world” (Heidegger) and thereby affectively “intra-act” (Barad) with and ‘perform’ the empirical knowledge. ‘ ‘Thrownness’ is Heidegger’s way of expressing...... into the world and being situated and attuned to it in specific ways through interest, fear, boredom or something else. Combing concepts from philosophy as well as psychology, the material and the affective turn allow us to rethink and elaborate on well-known discussions on qualitative research, representation......, positioning and situatedness. Instead of being stuck with traditional dichotomies, this conceptual language teaches us to think in connectivity and the qualities of this connectivity as the basic premise....

  20. Massachusetts Institute of Technology Plasma Fusion Center, 1988--1989 report to the President

    International Nuclear Information System (INIS)

    This report discusses the following topics on fusion energy: cold fusion; alcator confinement experiments; applied plasma physics research; fusion systems; coherent electromagnetic wave generation; and fusion technology and engineering

  1. Is operations research really research?

    OpenAIRE

    NJ Manson

    2006-01-01

    This paper takes a philosophical look at the Research in Operations Research. First, the questions "What is Research?" and "What is Operations Research?" are discussed. Next, the paper discusses why it is important to have a clear definition of research, especially in academia. The paper then discusses a research paradigm called 'Design Research'. Design Research is defined and compared with other research paradigms. Seven guidelines for understanding, executing, and evaluating Design Researc...

  2. Soft-X-ray tomography on Alcator C

    International Nuclear Information System (INIS)

    Using 80 miniature soft-X-ray detectors viewing along chords through a plasma cross-section at one toroidal location, tomographic reconstructions of emissivity have been obtained without the need for assuming any symmetry or rotation of the plasma. In one class of plasma discharges, it is found that a large m=1 oscillation, which previously had been ascribed to the rotation of an MHD instability, actually is not rotating at all. (author)

  3. Superconducting qualification program for TFCX and alcator DCT magnetic systems

    International Nuclear Information System (INIS)

    The purpose of the Magnetics Qualification Program is to demonstrate the feasibility of ICCS conductors for TF and PF coils for TFCX and DCT. Conductor requirements for these projects represent an advance over LCP conductors in peak field, overall current density, and in strand-to-strand decoupling. Achievement of these advanced parameters results in significant device performance improvement and cost savings over the performance achievable with the LCP ICCS Westinghouse/Airco Conductor

  4. Research Results Research Results

    Science.gov (United States)

    2009-04-01

    A Highly Efficient Route for Selective Phenol Hydrogenation to Cyclohexanone A Novel Mechanism Employed by KSHV to Maintain the Latent Infection was Revealed Breakthrough in the Synthesis of Interconnected NW/NT and NT/NW/NT Heterojunctions with Branched Topology GABA Transporter-1 Activity Modulates Hippocampal Theta Oscillation and Theta Burst Stimulation-Induced Long-Term Potentiation Meta-analysis of Vitamin D, Calcium and the Prevention of Breast Cancer New Findings on the Origin of TrpRS PKCd Regulates Cortical Radial Migration by Stabilizing the Cdk5 Activator P35 PKU Research Team Publishes Papers on Inhalation Exposure to Pollutant and Cancer Risk Progress of the Research on Arbitrarily Elliptical Invisibility Cloaks An Advance in Complete Oxidation of Formaldehyde at Low Temperatures

  5. Research organizations

    DEFF Research Database (Denmark)

    Larsen, Bøje; Aagaard, Peter

    in Copenhagen - we argue that a post-rational form of research activity is emerging which revert these features. We term this new type of research "enchanted research", "sciencetainment" and "Mode2-b research". The factors that facilitate this development include the boring style of conventional research......, growing competition for research funds, more project funding compared to institutional funding and a demand for accountability. Countervailing forces also exist, however....

  6. Papers presented at the eleventh topical conference on high-temperature plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This report contains the following eleven papers presented at the conference: Neutral Beam Diagnostics for Alcator C-Mod; A Study for the Installation of the TEXT HIBP on DIII-D; Time-domain Triple-probe Measurement of Edge Plasma Turbulence on TEXT-U; A Langmuir/Mach Probe Array for Edge Plasma Turbulence and Flow; Determination of Field Line Location and Safety Factor in TEXT-U; Hybrid ECE Imaging Array System for TEXT-U; First Results from the Phase Contrast Imaging System on TEXT-U; A Fast Tokamak Plasma Flux and Electron Density Reconstruction Technique; Time-series Analysis of Nonstationary Plasma Fluctuations Using Wavelet Transforms; Quantitative Modeling of 3-D Camera Views for Tokamak Divertors; and Variable-frequency Complex Demodulation Technique for Extracting Amplitude and Phase Information. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  7. Study of Scrape-Off-Layer Width in Ohmic and Lower Hybrid Wave Heated Double-Null Divertor Plasma in EAST%Study of Scrape-Off-Layer Width in Ohmic and Lower Hybrid Wave Heated Double-Null Divertor Plasma in EAST

    Institute of Scientific and Technical Information of China (English)

    王亮; 刘鹏; 蒋敏; 熊豪; 万宝年; 高翔; 郭后扬; 胡立群; 吴振伟; 朱思铮; 罗广南; 徐国盛; 常加峰; 张炜; 颜宁; 丁斯晔; 刘少承; 明廷凤; 汪惠乾

    2011-01-01

    Edge profiles in Ohmic and lower hybrid (LH) wave heated discharges in EAST are presented. A comparison of the measured profiles is made with those from the theoretical prediction for the scrape-off-layer (SOL) width. The edge plasma parameters are diagnosed by a triple probe divertor diagnostic system and fast reciprocating probes at the outer mid-plane. The experimental results show that the SOL width of double-null (DN) divertor plasmas in EAST appears to exhibit a negative dependence on the power crossing the separatrix, which is consistent with the collisional SOL scalings of JET and Alcator C-Mod. This will provide useful information for extrapolation to the ITER SOL width scaling for power deposition.

  8. Intra-shot MSE Calibration Technique For LHCD Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jinseok; Scott, Steve; Shiraiwa, Syun' ichi; Greenwald, Martin; Parker, Ronald; Wallace, Gregory

    2009-11-23

    The spurious drift in pitch angle of order several degrees measured by the Motional Stark Effect (MSE) diagnostic in the Alcator C-Mod tokamak1 over the course of an experimental run day has precluded direct utilization of independent absolute calibrations. Recently, the underlying cause of the drift has been identified as thermal stress-induced birefringence in a set of in-vessel lenses. The shot-to-shot drift can be avoided by using MSE to measure only the change in pitch angle between a reference phase and a phase of physical interest within a single plasma discharge. This intra-shot calibration technique has been applied to the Lower Hybrid Current Drive (LHCD) experiments and the measured current profiles qualitatively demonstrate several predictions of LHCD theory such as an inverse dependence of current drive efficiency on the parallel refractive index and the presence of off-axis current drive.

  9. A NOVEL X-RAY IMAGING CRYSTAL SPECTROMETER FOR DOPPLER MEASUREMENTS OF ION TEMPERATURE AND PLASMA ROTATION VELOCITY PROFILES

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Hill, K W; Scott, S; Ince-Cushman, A; Reinke, M; Rice, J E; Beiersdorfer, P; Gu, M F; Lee, S G; Broennimann, C; Eikenberry, E F

    2008-06-06

    A new type of X-ray imaging crystal spectrometer has been implemented on Alcator CMod for Doppler measurements of ion temperature and plasma rotation velocity profiles. The instrument consists of two spherically bent (102)-quartz crystals with radii of curvature of 1444 and 1385 mm and four 'PILATUS II' detector modules. It records spectra of He-like argon from the entire, 72 cm high, elongated plasma cross-section and spectra of H-like argon from a 20 cm high, central region of the plasma, with a spatial resolution of 1.3 cm and a time resolution of less than 20 ms. The new spectrometer concept is also of interest for the diagnosis of burning plasmas on future machines. This paper presents recent experimental results from Aclator C-Mod and discusses challenges in X-ray spectroscopy for the diagnosis of fusion plasmas on future machines.

  10. Imaging with Spherically Bent Crystals or Reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Hill, K W; Scott, S; Ince-Cushman, A; Reinke, M; Podpaly, Y; Rice, J E; Beiersdorfer, P

    2010-06-01

    This paper consists of two parts: Part I describes the working principle of a recently developed x-ray imaging crystal spectrometer, where the astigmatism of spherically bent crystals is being used with advantage to record spatially resolved spectra of highly charged ions for Doppler measurements of the ion-temperature and toroidal plasmarotation- velocity profiles in tokamak plasmas. This type of spectrometer was thoroughly tested on NSTX and Alcator C-Mod, and its concept was recently adopted for the design of the ITER crystal spectrometers. Part II describes imaging schemes, where the astigmatism has been eliminated by the use of matched pairs of spherically bent crystals or reflectors. These imaging schemes are applicable over a wide range of the electromagnetic radiation, which includes microwaves, visible light, EUV radiation, and x-rays. Potential applications with EUV radiation and x-rays are the diagnosis of laserproduced plasmas, imaging of biological samples with synchrotron radiation, and lithography.

  11. Modeling of Nonlinear Beat Signals of TAE's

    Science.gov (United States)

    Zhang, Bo; Berk, Herbert; Breizman, Boris; Zheng, Linjin

    2012-03-01

    Experiments on Alcator C-Mod reveal Toroidal Alfven Eigenmodes (TAE) together with signals at various beat frequencies, including those at twice the mode frequency. The beat frequencies are sidebands driven by quadratic nonlinear terms in the MHD equations. These nonlinear sidebands have not yet been quantified by any existing codes. We extend the AEGIS code to capture nonlinear effects by treating the nonlinear terms as a driving source in the linear MHD solver. Our goal is to compute the spatial structure of the sidebands for realistic geometry and q-profile, which can be directly compared with experiment in order to interpret the phase contrast imaging diagnostic measurements and to enable the quantitative determination of the Alfven wave amplitude in the plasma core

  12. Observation of Energetic Particle Driven Modes Relevant to Advanced Tokamak Regimes

    Energy Technology Data Exchange (ETDEWEB)

    R. Nazikian; B. Alper; H.L. Berk; D. Borba; C. Boswell; R.V. Budny; K.H. Burrell; C.Z. Cheng; E.J. Doyle; E. Edlund; R.J. Fonck; A. Fukuyama; N.N. Gorelenkov; C.M. Greenfield; D.J. Gupta; M. Ishikawa; R.J. Jayakumar; G.J. Kramer; Y. Kusama; R.J. La Haye; G.R. McKee; W.A. Peebles; S.D. Pinches; M. Porkolab; J. Rapp; T.L. Rhodes; S.E. Sharapov; K. Shinohara; J.A. Snipes; W.M. Solomon; E.J. Strait; M. Takechi; M.A. Van Zeeland; W.P. West; K.L. Wong; S. Wukitch; L. Zeng

    2004-10-21

    Measurements of high-frequency oscillations in JET [Joint European Torus], JT-60U, Alcator C-Mod, DIII-D, and TFTR [Tokamak Fusion Test Reactor] plasmas are contributing to a new understanding of fast ion-driven instabilities relevant to Advanced Tokamak (AT) regimes. A model based on the transition from a cylindrical-like frequency-chirping mode to the Toroidal Alfven Eigenmode (TAE) has successfully encompassed many of the characteristics seen in experiments. In a surprising development, the use of internal density fluctuation diagnostics has revealed many more modes than has been detected on edge magnetic probes. A corollary discovery is the observation of modes excited by fast particles traveling well below the Alfven velocity. These observations open up new opportunities for investigating a ''sea of Alfven Eigenmodes'' in present-scale experiments, and highlight the need for core fluctuation and fast ion measurements in a future burning-plasma experiment.

  13. Non-resonant destabilization of (1/1) internal kink mode by suprathermal electron pressure

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Aparicio, L.; Gates, D. A.; Gorelenkov, N.; Scott, S.; Bertelli, N.; Wilson, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Sugiyama, L. [MIT - Laboratory of Nuclear Science, Cambridge, Massachusetts 02139 (United States); Shiraiwa, S.; Irby, J.; Granetz, R.; Parker, R.; Baek, S. G.; Faust, I.; Wallace, G.; Mumgaard, R.; Gao, C.; Greenwald, M.; Hubbard, A.; Hughes, J.; Marmar, E. [MIT - Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); and others

    2015-05-15

    New experimental observations are reported on the structure and dynamics of short-lived periodic (1, 1) “fishbone”-like oscillations that appear during radio frequency heating and current-drive experiments in tokamak plasmas. For the first time, measurements can directly relate changes in the high energy electrons to the mode onset, saturation, and damping. In the relatively high collisionality of Alcator C-Mod with lower hybrid current drive, the instability appears to be destabilized by the non-resonant suprathermal electron pressure—rather than by wave-particle resonance, rotates toroidally with the plasma and grows independently of the (1, 1) sawtooth crash driven by the thermal plasma pressure.

  14. Action Research and Interactive Research

    DEFF Research Database (Denmark)

    Svensson, lennart; Nielsen, Kurt Aagaard

    2006-01-01

    The authors present trends in Nordic action research. They ask critical questions in the development towards mode 2 and points out alternative roads for a scientific consolidation of action research and interactive research.......The authors present trends in Nordic action research. They ask critical questions in the development towards mode 2 and points out alternative roads for a scientific consolidation of action research and interactive research....

  15. Research Design

    DEFF Research Database (Denmark)

    2017-01-01

    Gunnar Scott Reinbacher (editor) Antology.  Research Design : Validation in Social Sciences. Gunnar Scott Reinbacher: Introduction. Research design and validity. 15p Ole Riis: Creative Research design. 16 p Lennart Nørreklit: Validity in Research Design. 24p Gitte Sommer Harrits: Praxeological...... knowledge: An integrated strategy for combining "explaining" and "understanding". 22p Heidi Houlberg Salomonsen & Viola Burau: Comparative research designs. 40p Rasmus Antoft & Heidi Houlberg Salomonsen: Studying organizations by a Pragmatic Research Design: the case of qualitative case study  designs. 31p...... Kenneth Mølbjerg Jørgensen: Research as storrytelling: constructing reflexive research practice. 21p Lars Ole Bonde: Reflections on the relationship between research questions, design and methods in the research project "Receptive music therapy with female cancer patients in rehabilitation. 35p Gunnar...

  16. Multi-device studies of pedestal physics and confinement in the I-mode regime

    Science.gov (United States)

    Hubbard, A. E.; Osborne, T.; Ryter, F.; Austin, M.; Barrera Orte, L.; Churchill, R. M.; Cziegler, I.; Fenstermacher, M.; Fischer, R.; Gerhardt, S.; Groebner, R.; Gohil, P.; Happel, T.; Hughes, J. W.; Loarte, A.; Maingi, R.; Manz, P.; Marinoni, A.; Marmar, E. S.; McDermott, R. M.; McKee, G.; Rhodes, T. L.; Rice, J. E.; Schmitz, L.; Theiler, C.; Viezzer, E.; Walk, J. R.; White, A.; Whyte, D.; Wolfe, S.; Wolfrum, E.; Yan, Z.; Alcator C-Mod, the; Upgrade, ASDEX; DIII-D Teams

    2016-08-01

    This paper describes joint ITPA studies of the I-mode regime, which features an edge thermal barrier together with L-mode-like particle and impurity transport and no edge localized modes (ELMs). The regime has been demonstrated on the Alcator C-Mod, ASDEX Upgrade and DIII-D tokamaks, over a wide range of device parameters and pedestal conditions. Dimensionless parameters at the pedestal show overlap across devices and extend to low collisionality. When they are matched, pedestal temperature profiles are also similar. Pedestals are stable to peeling-ballooning modes, consistent with lack of ELMs. Access to I-mode is independent of heating method (neutral beam injection, ion cyclotron and/or electron cyclotron resonance heating). Normalized energy confinement H 98,y2  ⩾  1 has been achieved for a range of 3  ⩽  q 95  ⩽  4.9 and scales favourably with power. Changes in turbulence in the pedestal region accompany the transition from L-mode to I-mode. The L-I threshold increases with plasma density and current, and with device size, but has a weak dependence on toroidal magnetic field B T. The upper limit of power for I-modes, which is set by I-H transitions, increases with B T and the power range is largest on Alcator C-Mod at B  >  5 T. Issues for extrapolation to ITER and other future fusion devices are discussed.

  17. Investigation of dynamics of ELM crashes and their mitigation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pankin, Alexei Y. [Tech-X Corporation, Boulder, CO (United States)

    2015-08-14

    The accurate prediction of H-mode pedestal dynamics is critical for planning experiments in existing tokamaks and in the design of future tokamaks such as ITER and DEMO. The main objective of the proposed research is to advance the understanding of the physics of H-mode pedestal. Through advances in coupled kinetic-MHD simulations, a new model for H-mode pedestal and ELM crashes as well as an improved model for the bootstrap current will be developed. ELMmitigation techniques will also be investigated. The proposed research will help design efficient confinement scenarios and reduce transient heat loads on the divertor and plasma facing components. During the last two years, the principal investigator (PI) of this proposal actively participated in physics studies related to the DOE Joint Research Targets. These studies include the modeling of divertor heat load in the DIII-D, Alcator C-Mod, and NSTX tokamaks in 2010, and the modeling of H-mode pedestal structure in the DIII-D tokamak in 2011. It is proposed that this close collaboration with experimentalists from major US tokamaks continue during the next funding period. Verification and validation will be a strong component of the proposed research. During the course of the project, advances will be made in the following areas; Dynamics of the H-mode pedestal buildup and recovery after ELM crashes – The effects of neutral fueling, particle and thermal pinches will be explored; Dynamics of ELM crashes in realistic tokamak geometries – Heat loads associated with ELM crashes will be validated against experimental measurements. An improved model for ELM crashes will be developed; ELM mitigation – The effect of resonant magnetic perturbations on ELMs stability and their evolution will be investigated; Development of a new bootstrap current model – A reduced model for will be developed through careful verification of existing models for bootstrap current against first-principle kinetic neoclassical simulations

  18. Final Report for "Investigation of dynamics of ELM crashes and their mitigation techniques"

    Energy Technology Data Exchange (ETDEWEB)

    Pankin, Alexei Y. [Tech-X Corporation, Boulder, CO (United States)

    2015-08-14

    The accurate prediction of H-mode pedestal dynamics is critical for planning experiments in existing tokamaks and in the design of future tokamaks such as ITER and DEMO. The main objective of the proposed research is to advance the understanding of the physics of H-mode pedestal. Through advances in coupled kinetic-MHD simulations, a new model for H-mode pedestal and ELM crashes as well as an improved model for the bootstrap current will be developed. ELMmitigation techniques will also be investigated. The proposed research will help design efficient confinement scenarios and reduce transient heat loads on the divertor and plasma facing components. During the last two years, the principal investigator (PI) of this proposal actively participated in physics studies related to the DOE Joint Research Targets. These studies include the modeling of divertor heat load in the DIII-D, Alcator C-Mod, and NSTX tokamaks in 2010, and the modeling of H-mode pedestal structure in the DIII-D tokamak in 2011. It is proposed that this close collaboration with experimentalists from major US tokamaks continue during the next funding period. Verification and validation will be a strong component of the proposed research. During the course of the project, advances will be made in the following areas; Dynamics of the H-mode pedestal buildup and recovery after ELM crashes – The effects of neutral fueling, particle and thermal pinches will be explored; Dynamics of ELM crashes in realistic tokamak geometries – Heat loads associated with ELM crashes will be validated against experimental measurements. An improved model for ELM crashes will be developed; ELMmitigation – The effect of resonant magnetic perturbations on ELMs stability and their evolution will be investigated; Development of a new bootstrap current model – A reduced model for will be developed throughcareful verification of existing models for bootstrap current against first-principle kinetic neoclassical simulations

  19. Preeclampsia Research

    Science.gov (United States)

    ... Media Resources Interviews & Selected Staff Profiles Multimedia Preeclampsia Research at the NICHD Skip sharing on social media links Share this: Page Content NICHD Research aims to detect, treat, and prevent this potentially ...

  20. Research circles

    DEFF Research Database (Denmark)

    Nordentoft, Helle Merete; Thomsen, Rie; Möller, Jonas;

    lifelong guidance policies. This paper presents `research circles´ as a way to develop guidance practices through long-term research relationships between practice and research. Research circles support a bottom up approach to policy development just like ELGPN considers to be necessary and required...... in career guidance development. In the paper we draw on the preliminary findings from an ongoing Nordic project: “The future of career guidance and educational counselling”. Specifically, we explore the career guidance practitioners´ response to research circles as means to professional development. We...... argue that this practicebased way of organizing research facilitates learning, and potentially, qualifies practice. The collaboration between researchers and practitioners in the research circle fosters a joint venture and an academic perspective on practice, which stimulates practitioners to step out...

  1. Full wave simulations of fast wave efficiency and power losses in the scrape-off layer of tokamak plasmas in mid/high harmonic and minority heating regimes

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, N.; Jaeger, E. F.; Hosea, J. C.; Phillips, C. K.; Berry, L.; Bonoli, P. T.; Gerhardt, S. P.; Green, D.; LeBlanc, B.; Perkins, R. J.; Qin, C. M.; Pinsker, R. I.; Prater, R.; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Wright, J. C.; Zhang, X. J.

    2015-12-17

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves (HHFW), have found strong interaction between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 2D and 3D AORSA results for the National Spherical Torus eXperiment (NSTX) have shown a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is removed from in front of the antenna by increasing the edge density. Here, full wave simulations have been extended for 'conventional' tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results in HHFW regime show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for C-Mod and EAST, which operate in the minority heating regime.

  2. Marketing research

    OpenAIRE

    Wienerová, Alžběta

    2013-01-01

    This bachelor’s thesis deals with marketing research of fair trade coffee market. Theoretical part is applied types of marketing research and characterization of theirs. It’s explained single steps of marketing research and activities which are practised in these. Final is chapter explained fiction of social responsible marketing. In practical part are information about fair trade certificate, about Starbucks and about purchase of coffee this corporate. After was maked research in on...

  3. Ethnographic research

    NARCIS (Netherlands)

    van Hulst, M.J.; Koster, Martijn; Vermeulen, Jeroen; Dubnick, Melvin; Bearfield, Domonic

    2015-01-01

    This entry outlines three aspects of ethnographic research. First, we describe in what way ethnographic research implies a distinct way of knowing. Second, we discuss the use of qualitative methods in ethnographic research. Third, we take up the role of writing, which is both a way of documenting re

  4. Atomic physics for fusion plasma spectroscopy; a soft x-ray study of molybdenum ions

    International Nuclear Information System (INIS)

    Understanding the radiative patterns of the ions of heavy atoms (Z approx-gt 18) is crucial to fusion experiments. The present thesis applies ab initio, relativistic calculations of atomic data to modeling the emission of molybdenum (Z = 42) ions in magnetically confined fusion plasmas. The models are compared to observations made in the Alcator C-Mod tokamak (Plasma Fusion Center, Massachusetts Institute of Technology), and the Frascati Tokamak Upgrade. Experimental confirmation of these models allows confidence in calculations of the total molybdenum concentration and quantitative estimates of the total power lost from the plasmas due to molybdenum line radiation. Charge states in the plasma core (Mo33+ to Mo29+) emit strong x-ray and XUV spectra which allow benchmarking of models for the spatial distribution of highly stripped molybdenum ions; the models only achieve agreement with observations when the rates of indirect ionization and recombination processes are included in the calculation of the charge state distribution of the central molybdenum ions. The total concentration of molybdenum in the core of the plasma is found, and the total power radiated from the plasma core is computed. Observations of line emission from more highly charged molybdenum ions (Mo36+ to Mo34+) are presented. open-quotes Bulkclose quotes molybdenum charge states (Mo25+ to Mo23+) emit complicated XUV spectra from a position in the plasma near C-Mod's half radius; spatial profiles of these ions' emission are analyzed. Models for the line-emission spectra of adjacent ions (Mo28+ to Mo26+) are offered, and the accuracy and limits of ab initio energy level calculations are discussed. open-quotes Edgeclose quotes charge states (Mo22+ to Mo15) extend to the last closed magnetic flux surface of the C-Mod plasma. The strongest features from these charge states are emitted in a narrow band from ∼70 Angstrom

  5. Research misconduct

    International Nuclear Information System (INIS)

    Good research practice is important to the scientific community. An awareness of what constitutes poor practice is important. Various types of research misconduct are defined in this article. The extent of research misconduct in the field of radiology has been assessed by contacting five English language radiology journals. Redundant or duplicate publication has been reported infrequently, Radiology (1), American Journal of Roentgenology (3), Clinical Radiology (3), British Journal of Radiology (2) and European Radiology (1). The issue of how the radiology community might tackle research misconduct is discussed with reference to guidance from the Medical Research Council, the Wellcome Trust and the Committee of Publication Ethics

  6. Descriptive Research

    DEFF Research Database (Denmark)

    Wigram, Anthony Lewis

    2003-01-01

    Descriptive research is described by Lathom-Radocy and Radocy (1995) to include Survey research, ex post facto research, case studies and developmental studies. Descriptive research also includes a review of the literature in order to provide both quantitative and qualitative evidence of the effect...... starts will allow effect size calculations to be made in order to evaluate effect over time. Given the difficulties in undertaking controlled experimental studies in the creative arts therapies, descriptive research methods offer a way of quantifying effect through descriptive statistical analysis...

  7. Research Impact and Educational Research

    Science.gov (United States)

    Oancea, Alis

    2013-01-01

    Based on a 2010-11 study involving senior researchers from seven disciplines, this article explores critically some of the diverse interpretations of impact in different disciplines, sub-fields and modes of research, and researchers' views about how these interpretations articulate with top-down impact agendas and with university structures…

  8. Research 101: Understanding Educational Research

    Science.gov (United States)

    Murray, Angela; Bagby, Janet; Sulak, Tracey

    2010-01-01

    Currently, the Montessori community is increasing its focus on the importance of research. The purpose of this article is to provide some background for critical readers of research related to Montessori education and to provide the tools to implement these findings in one's own Montessori work. Research articles are generally organized in a way…

  9. Researching Practice and Practicing Research

    Science.gov (United States)

    DiPardo, Anne

    2011-01-01

    When works of teacher scholars were recognized with major National Council of Teachers of English (NCTE) research awards, and the sections and conferences instituted research initiatives of their own, many were filled with the soaring hope that a new synergy was in the making. The "Research in the Teaching of English" (RTE) Alan C. Purves Award,…

  10. Animal research

    DEFF Research Database (Denmark)

    Olsson, I.A.S.; Sandøe, Peter

    2012-01-01

    in research is analyzed from the viewpoint of three distinct ethical approaches: contractarianism, utilitarianism, and animal rights view. On a contractarian view, research on animals is only an ethical issue to the extent that other humans as parties to the social contract care about how research animals...... are faring. From the utilitarian perspective, the use of sentient animals in research that may harm them is an ethical issue, but harm done to animals can be balanced by benefit generated for humans and other animals. The animal rights view, when thoroughgoing, is abolitionist as regards the use of animals......This article presents the ethical issues in animal research using a combined approach of ethical theory and analysis of scientific findings with bearing on the ethical analysis. The article opens with a general discussion of the moral acceptability of animal use in research. The use of animals...

  11. Researcher positioning

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Khawaja, Iram

    2009-01-01

    abstract  This article focuses on the complex and multi-layered process of researcher positioning, specifically in relation to the politically sensitive study of marginalised and ‘othered' groups such as Muslims living in Denmark. We discuss the impact of different ethnic, religious and racial...... political and personal involvement by the researcher, which challenges traditional perspectives on research and researcher positioning. A key point in this regard is the importance of constant awareness of and reflection on the multiple ways in which one's positioning as a researcher influences the research...... process. Studying the other calls for close reflections on one's own position, theoretically, personally, and politically, taking into account one's complicity in either overcoming or reproducing processes of othering and marginalisation. [i] We use the term (ethnic) minoritised, not as a distinction...

  12. Centering research

    DEFF Research Database (Denmark)

    Katan, Lina Hauge; Baarts, Charlotte

    findings We then propose a set of experimentally designed curricular frameworks that have been shown to alter student engagement in reading and writing, encouraging their learning to become more research-like. Finally, we return to the literature on research-based teaching, asking how an emphasis......Research-based teaching has long been a distinguishing trait of higher education. Engaging students in research-like processes has been employed to great effect in learning and continues to be encouraged by educational studies. The literature on this subject reflects how ‘technical’ or ‘field......’ exercises tend to dominate the common understandings of research-based learning. Here we address a specific area of inquiry overlooked by previous studies: whether and how reading, thinking and writing indeed share the same learning potentials as the practical foundation for research-based teaching...

  13. Research Methodology

    CERN Document Server

    Rajasekar, S; Philomination, P

    2006-01-01

    In this manuscript various components of research are listed and briefly discussed. The topics considered in this write-up cover a part of the research methodology paper of Master of Philosophy (M.Phil.) course and Doctor of Philosophy (Ph.D.) course. The manuscript is intended for students and research scholars of science subjects such as mathematics, physics, chemistry, statistics, biology and computer science. Various stages of research are discussed in detail. Special care has been taken to motivate the young researchers to take up challenging problems. Ten assignment works are given. For the benefit of young researchers a short interview with three eminent scientists is included at the end of the manuscript.

  14. Avian Research

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    <正>Aims and Scope Avian Research is an open access,peer-reviewed journal publishing high quality research and review articles on all aspects of ornithology from all over the world.It aims to report the latest and most significant progress in ornithology and to encourage exchange of ideas among international ornithologists.As an Open Access journal,Avian Research provides a unique opportunity to publish high quality contents that will be internationally accessible to any reader at no cost.

  15. Research methodology

    DEFF Research Database (Denmark)

    Kuada, John

    This book deals with how students should use of research methods in their university projects. It aims at helping students in developing comprehensive research strategies for their projects. It also provides introduction to issues of philosophy of science as applied in the social sciences....... That is it provides them with a fair understanding of the root assumptions that guide researchers in their investigations and how these assumptions inform their theoretical thinking and choice of methods....

  16. Action research - applied research, intervention research, collaborative research, practitioner research, or praxis research?

    OpenAIRE

    Eikeland, Olav

    2012-01-01

    "This article relates common ways of conceptualising action research as 'intervention', 'collaboration', 'interactive research', 'applied research', and 'practitioner research' to a number of different ways of knowing, extracted from the works of Aristotle. The purpose is not to disavow any of these practices but to expand the philosophical, methodological, and theoretical horizon to contain the Aristotelian concept of praxis. It is claimed that praxis knowing needs to be comprehended in orde...

  17. Researcher Positioning

    DEFF Research Database (Denmark)

    Khawaja, Iram; Mørck, Line Lerche

    2009-01-01

    , of membership in a minoritised1 or majoritisedgroup, and the influence of different theoretical and methodological outlooks on ourcommon goal of trying to transcend existing othering and objectifying representationsof Muslims in Western societies. This process sometimes entails a direct political andpersonal...... involvement by the researcher, which challenges traditional perspectives onresearch and researcher positioning. A key point in this regard is the importance ofconstant awareness of and reflection on the multiple ways in which one's positioningas a researcher influences the research process. Studying the other...

  18. Clinical Research

    DEFF Research Database (Denmark)

    Christensen, Irene

    2016-01-01

    for years to come. This paper seeks to provide insights into ramp-up management studies through providing an agenda for conducting collaborative clinical research and extend this area by proposing how clinical research could be designed and executed in the Ramp- up management setting.......This paper is about the logic of problem solving and the production of scientific knowledge through the utilisation of clinical research perspective. Ramp-up effectiveness, productivity, efficiency and organizational excellence are topics that continue to engage research and will continue doing so...

  19. Letterform research

    DEFF Research Database (Denmark)

    Beier, Sofie

    2016-01-01

    This paper looks into the history of letterform research and discusses why the discipline has yet to make the big break within design research. By highlighting two of the most popular focus areas (letter distinctiveness and the role of serifs) and by discussing various forms of methodological...... shortcomings, the paper suggests that future research into letterforms should (1) draw on results from the field of reading research (2) be based on test material informed by design knowledge and (3) move away from the former tendency of looking for universal answers....

  20. Research Review

    OpenAIRE

    Anonymous

    1981-01-01

    Research Reviewed: "Global Modeling After Its First Decade"; "Monthly Food Price Forecasts"; "Costs of Marketing Slaughter Cattle: Computerized versus Conventional Auction Systems"; "Survival Strategies for Agricultural Cooperatives"

  1. Research Review

    Science.gov (United States)

    Serig, Dan, Ed.

    2010-01-01

    This research review is dedicated to the memory of William Safire (1929-2009). A visionary leader, Safire brought other visionaries, researchers, educators, artists, and policymakers together to explore the confluence of arts education and neuroscience. He fostered the new field of neuroeducation in his work as chair of The Dana Foundation in…

  2. Remote Research

    CERN Document Server

    Tulathimutte, Tony

    2011-01-01

    Remote studies allow you to recruit subjects quickly, cheaply, and immediately, and give you the opportunity to observe users as they behave naturally in their own environment. In Remote Research, Nate Bolt and Tony Tulathimutte teach you how to design and conduct remote research studies, top to bottom, with little more than a phone and a laptop.

  3. Research Review

    Science.gov (United States)

    Serig, Dan

    2011-01-01

    In this review, the author explores an often-used process in research--the mind map. He uses this method in his own research and artwork. He also uses this extensively with students, particularly master students when they are trying to surround issues in their thesis projects. Mind maps are closely associated with brainstorming, as brainstorming…

  4. Avian Research

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    <正>Aims and Scope Avian Research is an open access,peer-reviewed journal publishing high quality research and review articles on all aspects of ornithology from all over the world.It aims to report the latest and most significant progress in ornithology and to encourage exchange of ideas among international ornithologists.As an Open Access journal,

  5. Avian Research

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>Aims and Scope Avian Research is an open access,peer-reviewed journal publishing high quality research and review articles on all aspects of ornithology from all over the world.It aims to report the latest and most significant progress in ornithology and to encourage exchange of ideas among international ornithologists.As an Open Access journal,

  6. Action Research

    Science.gov (United States)

    Milton-Brkich, Katie Lynn; Shumbera, Kristen; Beran, Becky

    2010-01-01

    Defined as "any systemic inquiry conducted by teachers... for the purpose of gathering information about how their particular schools operate, how they teach, and how their students learn" (Mertler, 2009), "action research" is empowering and professional research done by teachers to inform and improves their own practices. Although there are many…

  7. Rehabilitation Research.

    Science.gov (United States)

    Wright, George N.; Trotter, Ann Beck

    A total of 97 studies are reported in this review of research in vocational rehabilitation. Projects were selected on the following criteria: (1) pertinence to rehabilitation counseling practice, (2) research approach, (3) broad generalizability, and (4) supported by the Vocational Rehabilitation Administration for a one-to-five-year period and…

  8. Design Research

    DEFF Research Database (Denmark)

    aspects – in terms of features and approaches – that characterize all strands of research disciplines addressing design, Design Research undertakes an in depth exploration of the social processes involved in doing design, as well as analyses of the contexts for design use. The book further elicits......Design Research is a new interdisciplinary research area with a social science orientation at its heart, and this book explores how scientific knowledge can be put into practice in ways that are at once ethical, creative, helpful, and extraordinary in their results. In order to clarify the common...... ‘synergies from interdisciplinary perspectives’ by discussing and elaborating on differing academic perspectives, theoretical backgrounds, and design concept definitions, and evaluating their unique contribution to a general core of design research. This book is an exciting contribution to this little...

  9. Design Research

    DEFF Research Database (Denmark)

    Design Research is a new interdisciplinary research area with a social science orientation at its heart, and this book explores how scientific knowledge can be put into practice in ways that are at once ethical, creative, helpful, and extraordinary in their results. In order to clarify the common...... aspects – in terms of features and approaches – that characterize all strands of research disciplines addressing design, Design Research undertakes an in depth exploration of the social processes involved in doing design, as well as analyses of the contexts for design use. The book further elicits...... ‘synergies from interdisciplinary perspectives’ by discussing and elaborating on differing academic perspectives, theoretical backgrounds, and design concept definitions, and evaluating their unique contribution to a general core of design research. This book is an exciting contribution to this little...

  10. Research report

    International Nuclear Information System (INIS)

    The SURRC (Scottish Universities Research and Reactor Centre) is a multidisciplinary research centre shared by a consortium of Scottish Universities. Funding is jointly by the University Funding Committee and commercially from Research Councils, government departments and industry. The focus of research lies in earth, environmental and biomedical sciences. The research activities are discussed under the following headings: environmental radioactivity and nuclear geochemistry, neutron activation analysis, inductively coupled plasma-mass spectrometry, body composition studies, stable isotopes in biological sciences, nuclear physics, luminescence dating and dosimetry radiation effects in electrical insulation, gamma-ray irradiation processing, radiogenic isotopes in geology, stable isotope geology, laser microprobe mass spectrometry for geology and NERC Radiocarbon Laboratory work. There are also reports on the reactor itself; reactor operation, production of radioactive isotopes and application of radioactive tracers. The educational aspects of the Centre, safety aspects, staffing, funding and all publications are reported. (UK)

  11. Research reactors

    International Nuclear Information System (INIS)

    This article proposes an overview of research reactors, i.e. nuclear reactors of less than 100 MW. Generally, these reactors are used as neutron generators for basic research in matter sciences and for technological research as a support to power reactors. The author proposes an overview of the general design of research reactors in terms of core size, of number of fissions, of neutron flow, of neutron space distribution. He outlines that this design is a compromise between a compact enough core, a sufficient experiment volume, and high enough power densities without affecting neutron performance or its experimental use. The author evokes the safety framework (same regulations as for power reactors, more constraining measures after Fukushima, international bodies). He presents the main characteristics and operation of the two families which represent almost all research reactors; firstly, heavy water reactors (photos, drawings and figures illustrate different examples); and secondly light water moderated and cooled reactors with a distinction between open core pool reactors like Melusine and Triton, pool reactors with containment, experimental fast breeder reactors (Rapsodie, the Russian BOR 60, the Chinese CEFR). The author describes the main uses of research reactors: basic research, applied and technological research, safety tests, production of radio-isotopes for medicine and industry, analysis of elements present under the form of traces at very low concentrations, non destructive testing, doping of silicon mono-crystalline ingots. The author then discusses the relationship between research reactors and non proliferation, and finally evokes perspectives (decrease of the number of research reactors in the world, the Jules Horowitz project)

  12. 2014 Nuclear Fusion Prize Acceptance Speech 2014 Nuclear Fusion Prize Acceptance Speech

    Science.gov (United States)

    Snyder, P. B.

    2015-01-01

    It is a great honor to receive the 2014 Nuclear Fusion Prize, here at the 25th IAEA Fusion Energy Conference. On behalf of everyone involved in this work, I would like to thank the IAEA, the Nuclear Fusion journal team, the IOP, and specifically Mitsuru Kikuchi, for their support of this important award. I would also like to acknowledge the many important contributions made by the other ten papers nominated for this prize. Our paper investigates the physics of the H-mode pedestal in tokamaks, specifically the development of a predictive understanding of the pedestal structure based on electromagnetic instabilities which constrain it, and the testing of the resulting theoretical model (EPED) against detailed observations on multiple devices. In addition to making pedestal predictions for existing devices, the paper also presents predictions for ITER, including methods for optimizing its pedestal height and fusion performance. What made this work possible, and indeed a pleasure to be involved with, was an extensive set of collaborations, including theory-experiment, multi-institutional, and international collaborations. Many of these collaborations have gone on for over a decade, and have been fostered in part by the ITPA Pedestal Group. The eight authors of this paper, from five institutions, all made important contributions. Rich Groebner, Tom Osborne and Tony Leonard carried out dedicated experiments and data analysis on the DIII-D tokamak, testing the EPED model over a very wide range of parameters. Jerry Hughes led dedicated experiments on Alcator C-Mod which tested the model at high magnetic field and pedestal pressure. Marc Beurskens carried out experiments and data analysis on the JET tokamak, testing the model at large scale. Xueqiao Xu conducted two-fluid studies of diamagnetic stabilization, which enabled a more accurate treatment of this important effect. Finally, Howard Wilson and I have been working together for many years to develop analytic formalism

  13. Bioprocessing research

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, E.N.

    1996-06-01

    This section describes research and development activities performed for the Fossil Energy Bioprocessing Research Program. This program includes fundamental research for coal applications that investigates advanced reactor design for conversion of coal and coal liquids, the use of enzymes in pure organic media, and development of biological processes for the conversion of coal residuum. In addition, the program includes studies on advanced bioreactor systems for the treatment of gaseous substrates and the conversion to liquid fuels, removal of heteroatoms from heavy oils, renewable hydrogen production, remediation of oil containing soils. The program also includes natural gas and oil technology partnership support.

  14. Researching Undergraduate Social Science Research

    Science.gov (United States)

    Rand, Jane

    2016-01-01

    The experience(s) of undergraduate research students in the social sciences is under-represented in the literature in comparison to the natural sciences or science, technology, engineering and maths (STEM). The strength of STEM undergraduate research learning environments is understood to be related to an apprenticeship-mode of learning supported…

  15. Action Research and Interactive Research

    DEFF Research Database (Denmark)

    First part of the book is written by senior researchers on specific issues like validity, gender, new forms of organisations, methodologies and methods, earlier and new trends. - The second part of the book is written by doctoral students reporting experiences doing action research in their PhD-projects....

  16. Research Matters

    Science.gov (United States)

    VanDeWeghe, Rick

    2004-01-01

    Educator and researcher Robert J. Sternberg's two theories, the theory of successful intelligence and theory of wisdom, are discussed. The teachers who wish to nurture students' expertise should take care of their analytical ability, creative and practical thinking.

  17. Researching Experiences

    DEFF Research Database (Denmark)

    Gjedde, Lisa; Ingemann, Bruno

    for researching experiences in a variety of settings ranging from the museum, to news photography, and interactive media. The research led to the development of a set of methodological tools and approaches we term the ReflexivityLab. The interaction in the experimental situation between the media and body......, dialogue, moods, values and narratives have been investigated qualitatively with more than sixty informants in a range of projects. The processual methodological insights are put into a theoretical perspective and also presented as pragmatic dilemmas.      Researching Experiences is relevant not only...... for students and researchers in media and communication studies but also for practitioners within the fields of media, communication and experience design....

  18. Research Reports

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Centers for Medicare and Medicaid Services (CMS) research efforts span many topics, methods, and interests. Some projects address the Agencys immediate...

  19. Disaster Research

    DEFF Research Database (Denmark)

    and anthropology of disaster. The methodological and theoretical contributions underlining a specific approach to disasters are discussed and illustrative empirical cases are examined that support and further inform the proposed approach to disaster research. The book thus provides unique insights into fourteen......Given the tendency of books on disasters to predominantly focus on strong geophysical or descriptive perspectives and in-depth accounts of particular catastrophes, Disaster Research provides a much-needed multidisciplinary perspective of the area. This book is is structured thematically around key...... approaches to disaster research from a range of different, but often complementary academic disciplines. Each chapter presents distinct approaches to disaster research that is anchored in a particular discipline; ranging from the law of disasters and disaster historiography to disaster politics...

  20. Research Review

    OpenAIRE

    Anonymous

    1985-01-01

    Research Reviewed: "Future Agricultural Technology and Resource Conservation"; "Economies of Scale, Competitiveness, and Trade Patterns within the European Community"; "Federal Price Programs for the American Dairy Industry: Issues and Alternatives"

  1. Research essentials.

    Science.gov (United States)

    English, Christine; Pengelly, Theresa

    2016-04-01

    A RESEARCHER needs to select a methodology and methods that fit the purpose of the study and will be able to answer the questions it poses. Clarifying viewpoints about epistemology (the philosophical theory of knowledge) and ontology (the nature of reality) is also important because these perspectives can affect the choice of study design. Consideration must also be given to any specific criteria in the research proposal bid criteria. PMID:27063043

  2. Research Cycles

    OpenAIRE

    Bramoullé, Yann; Saint-Paul, Gilles

    2006-01-01

    This paper studies the dynamics of fundamental research. We develop a simple model where researchers allocate their effort between improving existing fields and inventing new ones. A key assumption is that scientists derive utility from recognition from other scientists. We show that the economy can be either in a regime where new fields are constantly invented, and then converges to a steady state, or in a cyclical regime where periods of innovation alternate with periods of exploitation. Ou...

  3. Marketing Research

    OpenAIRE

    Spieglerová, Karin

    2013-01-01

    Bachelor thesis titled “Marketing Research” is made up of two parts. The first being the theoretical part, which covers the basic knowledge about a market and how it can be marketed. It also focuses on the identification for the need for marketing research, whilst providing the information about targets and about the ways of implementing the research and its overall progress (preparation, analysis and interpretation of results). In this part there is also a description of the various types of...

  4. Climate Research

    OpenAIRE

    Hamann, Ilse; Meier zu Verl, Christian; Horstmann, Wolfram

    2011-01-01

    The findings described in the following sections of this chapter are to a large extent based on an analysis of documents available to me at the institution where I work, i.e. in the Data Management department (DM) of the German Climate Computing Centre (DKRZ, Deutsches Klimarechenzentrum), or are part of websites of other institutions in the climate research community. Additional information about aspects of the research infrastructure in climate science comes from what I could glean from the...

  5. Latvian research

    International Nuclear Information System (INIS)

    The Latvian Council of Science asked the Danish Research Councils and the Danish Academy for Technical Sciences for help in evaluating Latvian scientific research. The background for this request was the Latvian desire to stimulate an approach towards full integration in the European society. Based on reports, site visits and interviews, 19 panels of experts covering all subject areas prepared evaluation reports. These detailed evaluations of actual research projects are included in the publication in addition to general recommendations. The panels recommend that Latvian authorities take into consideration when planning scientific research, especially with regard to those branches which contribute to the industrial development and social and economic sciences, that a balance should be made between long range basic, and short range applied, science activities. Despite the very serious economic conditions in Latvia, it was also advised that immediate measures should be taken to ensure a stable funding of the research system as the future development of Latvian society is dependent on the stability and high quality of its research activities. Other recommendations are given in detail. (AB)

  6. Quantitative research.

    Science.gov (United States)

    Watson, Roger

    2015-04-01

    This article describes the basic tenets of quantitative research. The concepts of dependent and independent variables are addressed and the concept of measurement and its associated issues, such as error, reliability and validity, are explored. Experiments and surveys – the principal research designs in quantitative research – are described and key features explained. The importance of the double-blind randomised controlled trial is emphasised, alongside the importance of longitudinal surveys, as opposed to cross-sectional surveys. Essential features of data storage are covered, with an emphasis on safe, anonymous storage. Finally, the article explores the analysis of quantitative data, considering what may be analysed and the main uses of statistics in analysis.

  7. Management research

    International Nuclear Information System (INIS)

    The 1988 progress report of the Management Research center (Polytechnic School, France), is presented. The Center research programs include the management of different organizations, such as industry, administrative systems, hospitals and cultural systems. The investigations performed concern the improvement and better knowledge of the new methods of analysis: the role of the speech, the logic conflicts; the crisis development, symptoms and effects; the relationship between the management practices and the prevailing ideas or theories. The approach adopted by the scientists involves the accurate analysis of the essential management activities. The investigations carried out in 1988 are summarized. The published papers, the congress communications and the thesis are listed

  8. RESEARCH COMMUNITIES

    OpenAIRE

    HUGO ESCOBAR-MELO; WILSON LÓPEZ-LÓPEZ; ALFONSO SÁNCHEZ PILONIETA

    2006-01-01

    This article constitutes an anthology of the research in the Department of Psychology of the UniversidadJaveriana and it takes as point of consultations the book Saber, sujeto y sociedad: Una década de investigación enPsicología published in the year 2006 by the Editorial Pontificia Universidad Javeriana as a collective work;it shows the research itinerary of the groups and authors which have worked in multiple problematicnucleus like the affective bonds in terms of emotional security and car...

  9. Research Advances

    Science.gov (United States)

    King, Angela G.

    2005-01-01

    Researchers in the Department of Bioengineering at Rice University are developing a new approach for fighting cancer, based on nanoshells that can both detect and destroy cancerous cells. The aim is to locate the cells, and be able to make a rational choice about whether they need to be destroyed and if possible they should immediately be sent for…

  10. Research Review

    OpenAIRE

    Anonymous

    1982-01-01

    Research Reviewed: "Cross-Sectional Analysis of Wheat Import Demand among Middle-Income Developing Countries"; "Some Lessons from Wingspread: A Report on the National Rural Symposium"; "Growth in U.S. Agricultural Capacity and Utilization: We Need to Know More about It"; "Mexico's Agricultural Dilemma"; "Modeling and Measuring Natural Resource Substitution"; "Environmental Regulation and the U.S. Economy"

  11. Research Review

    OpenAIRE

    Anonymous

    1982-01-01

    Research Reviewed: "Tax Burdens in American Agriculture: An Intersectoral Comparison"; "Asian Village Economy at the Crossroads: An Economic Approach to Institutional Change"; "The Agrarian Question and Reformism in Latin America"; "On the Misuse of Theil's Inequality Coefficient"; "Comment on the Misuse of Theil's Inequality Coefficient"

  12. Research Review

    OpenAIRE

    Anonymous

    1985-01-01

    Research Reviewed: "When Are Export Subsidies Rational? A Comment"; "Export Subsidies Are Still Irrational"; "When Are Export Subsidies Rational? A Reply"; "Modeling Farm Decisions for Policy Analysis"; "Selected Writing on Agricultural Policy and Economic Analysis"; "Land Reform, American Style"; "Livestock Response Functions"

  13. Research Blog

    NARCIS (Netherlands)

    Jautze, K.J.

    2014-01-01

    Welcome to my personal research blog. I'm a PhD candidate from the Netherlands who has an interest in language and literature. In the project The Riddle of Literary Quality my colleagues and I explore the assumption that formal characteristics play a role in the aesthetic appreciation of novels. In

  14. Research revolution?

    Science.gov (United States)

    2008-05-01

    Valérie Pecresse has been a member of the French National Assembly (Yvelines department) since 2002. She rose to prominence as the combative spokeswoman for Nicolas Sarkozy's centre-right UMP party during the 2007 presidential race, after which she was appointed minister for higher education and research.

  15. Research Review

    OpenAIRE

    Anonymous

    1982-01-01

    Research Reviewed: "Specification of Bernoullian Utility Function in Decision Analysis: Comment"; "Linear Programming, Duality, and Cost of Production"; "Changes in the Chicago Corn Basis, 1960-75"; "A Survey of Agricultural Economics Literature"; "The Methodology of Economics (or How Economists Explain)"; "Resources and Development: Natural Resource Policies and Economic Development in an Interdependent World"

  16. Quantitative research

    DEFF Research Database (Denmark)

    Wigram, Anthony Lewis

    2003-01-01

    possible and desirable. It is not just a type of research done in a laboratory, or by PhD students. Some for of reliable measurement can be applied to many clinical situationsto evaluate the effects of therapy over time, or the difference between clients who receive therapy and those who don't. Evaluating...

  17. Research evaluation

    DEFF Research Database (Denmark)

    Pedersen, David Budtz

    2014-01-01

    decisions that have marked the period since the first edition was researched and published. In addition, to help make ESTE more global and interdisciplinary in scope and reach, the second edition will engage consultants from ethics centers around the world, and will feature the revised title Ethics, Science...

  18. Research medicine

    International Nuclear Information System (INIS)

    Highlights of the research effort during 1978 and 1979 include the development and use of a 280-crystal position tomograph; use of 11C-labeled methionine in studies of heart metabolism and brain metabolism in humans; and studies of the megakaryocytic cell system

  19. Types of Cancer Research

    Science.gov (United States)

    An infographic from the National Cancer Institute (NCI) describing the four broad categories of cancer research: basic research, clinical research, population-based research, and translational research.

  20. Globalized research

    Directory of Open Access Journals (Sweden)

    Carlos Renato Zacharias

    2013-06-01

    Full Text Available The current issue of IJHDR begins by a now classical dilemma relative to the high dilutions: if they lack biological effects, how might they cause adverse effects? The plausibility of the implausible is once again the subject of a letter addressed to this Editor. The present issue further features three articles from Indian authors, which somehow makes the occasion special, and worthy of reflection: what is going on in Indian homeopathy? As it is known, India has always played a significant role in the homeopathic stage by contributing with original clinical protocols and approaches. More recently, India has shown the world unexpected scientific features of the high dilutions. The natural and cultural diversity of India seems to influence the research it conducts, which ranges from physicochemical and biological studies performed in research centers and universities to clinical trials conducted in hospitals, in addition to a major concern with education. India has thus become one of the main centers concerned with the scientific side of homeopathy, which is further attested by the organization of, and participation in major scientific meetings like the LMHI congress of 2011, GIRI meetings, and the latest HRI conference, and publication in IJHDR and other scientific journals. As an example of the multiple interests of homeopathic research in India, one article in this issue of IJHDR addresses a fundamental research problem, another the patients’ satisfaction, and the third the perspective of undergraduates on the teaching of homeopathy. This same movement observed in India has been observed in other countries like Brazil and Russia among others, following many European countries, making possible and feasible the existence of an international scientific network connecting the various groups devoted to HD research across the world. IJHDR is proud to participate on this endeavor!

  1. Research Results

    Science.gov (United States)

    2012-12-01

    Achievements in Sino-German Interdisciplinary Major Research Project Published by Small A Conserved Proline Switch on the Ribosome Facilitates the Recruitment and Binding of trGTPases Air Pollution Contributes in Sunshine Dimming in China Role of Lymphatic Trafficking and Biodistribution Soft Fibrin Gels Promote Selection and Growth of Tumorigenic Cells Targeted Therapy: The New Lease on Life for Acute Promyelocytic Leukemia, and Beyond The Structural Basis for the Sensing and Binding of Cyclic di-GMP by STING Research on Atomic-Scale Investigation of Li Storage Mechanism in Spinel Li4Ti5O12 NSFC Funded Project Made Significant Progress in Intelligent Nanomaterial and Device Palaeobotany and the Evolution of the Monsoon in China Non Heme System Asymmetric Epoxidation Reaction Made Progress Rapid Advancement of Immunology Study in China Chinese Experts Successfully Produced Transgenic Animals from Haploid Embryonic Stem Cells

  2. RESEARCH UPDATES

    OpenAIRE

    Anonymous

    1999-01-01

    Includes: Price and Distribution Variations for Value-Added Vegetable Products in California. Jim Ahern and Marianne Wolf, Professors, Agribusiness Department, Cal Poly State University SLO. Case Study of Heritage Ranch, "Wolf-Friendly Beef." Helen L. Aquino, Graduate Research Assistant, Agricultural Economics, New Mexico State University. Branding Locally Grown Fruit and Vegetables Via State Logos. John R. Brooker, David B. Eastwood, and Morgan D. Gray; Faculty Members; Department of Agricul...

  3. Biobank research

    OpenAIRE

    Leppäluoto, Juhani

    2012-01-01

    Biobank research is a new and growing branch in human health sciences. Biobank is acollection of blood or tissue samples – from which DNA is available – and pieces of informationabout the living habits and health of the subjects who have donated samples to thebiobank. The purpose of biobanks is to find out risk genes related to common diseases inthe population, such as cardiovascular or mental diseases and cancer, or primary genescausing a particular disease. Establishment of biobanks is base...

  4. Dialogue Research

    DEFF Research Database (Denmark)

    Duelund, Peter

    1991-01-01

    Departing from Anthony Giddens´s theory of structuration and the concept double hermeneutics and Jürgen Habermas´s Theory of Communicative Actions the article specifies theories and methods af dialogue as method in the humanities and social sciences. The article concludes by pointing at dialogues...... as a new theoretical, methodological and empirical research concept i an society where the traditional planning instruments have failed....

  5. Research Instruments

    Science.gov (United States)

    1992-01-01

    The GENETI-SCANNER, newest product of Perceptive Scientific Instruments, Inc. (PSI), rapidly scans slides, locates, digitizes, measures and classifies specific objects and events in research and diagnostic applications. Founded by former NASA employees, PSI's primary product line is based on NASA image processing technology. The instruments karyotype - a process employed in analysis and classification of chromosomes - using a video camera mounted on a microscope. Images are digitized, enabling chromosome image enhancement. The system enables karyotyping to be done significantly faster, increasing productivity and lowering costs. Product is no longer being manufactured.

  6. Research Assistant Position Huihui Zeng Research Laboratory

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Research Laboratory of Element-Organic and Organoselenium-Drug Chemistry and Pharmacology was set up in 2003. This lab belongs to the Associated- Research Group of Anticancer Drug Research and Development. Our researches focus on the following fields: new

  7. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... NIH Research Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library Resources ...

  8. Mountain research

    Science.gov (United States)

    The newly incorporated International Mountain Society (IMS) will in May begin publication of an interdisciplinary scientific journal, Mountain Research and Development. The quarterly will be copublished with the United National University; additional support will come from UNESCO.A primary objective of IMS is to ‘help solve mountain land-use problems by developing a foundation of scientific and technical knowledge on which to base management decisions,’ according to Jack D. Ives, president of the Boulder-based organization. ‘The Society is strongly committed to the belief that a rational worldwide approach to mountain problems must involve a wide range of disciplines in the natural and human sciences, medicine, architecture, engineering, and technology.’

  9. Research Report

    Science.gov (United States)

    Dawes, Lyn

    2004-06-01

    This paper examines what is important about talk between learners during school science and, having identified this, suggests how we can ensure that what we consider important happens. By looking at the interaction between teachers and learners talking about science, it is possible to indicate ways in which learners can be helped to continue this learning conversation with one another when teacher support is withdrawn. Strategies for teaching and learning are examined. The paper reports on the findings of a research project designed to teach children how to negotiate their ideas about science concepts through rational dialogue. Children's development of scientific concepts in classrooms is undertaken through structured activity and mediated through oral language. Children must move forward simultaneously in their use of specialized vocabulary and in their understanding of current scientific explanations, models and ideas. New language and new ways of using language are learned by doing, which means for children, primarily speaking and listening. Children's understanding of science can benefit from teaching them to understand that spoken language is a powerful tool for thinking together.

  10. Research Results

    Science.gov (United States)

    2012-01-01

    In situ Oxidation Study of Pt (110) and Its Interaction with CO Chinese Scientists Published a Paper on Prevention of Drug Craving and Relapse by Memory Retrieval-extinction Procedure in Science Series Papers Published in Energy Policy: Modeling Energy Use of China's Road Transport and Policy Evaluation Breakthrough in the Ambient Catalytic Destruction of Formaldehyde Novel Findings for High Altitude Adaptation from the Yak Genome Binary Colloidal Structures Assembled through Ising Interactions Reemergence of superconductivity at 48K in Compressed Iron Selenide Based Superconductors Nucleosomes Suppress Spontaneous Mutations Base-Specifically in Eukaryotes Single-Chain Fragmented Antibodies Guided SiRNA Delivery in Breast Cancer Does Yeast Suicide? China Scientists Developed Important Methodologies for Spatiotemporal Detecting and Manipulating of Cellular Activities Scorpions Inspire Chinese Scientists in Making Bionic Non-eroding Surfaces for Machinery Research on Phylogenetic Placement of Borthwickia and Description of a New Family of Angiosperms, Borthwickiaceae Plasmoid Ejection and Secondary Current Sheet Generation from Magnetic Reconnection in Laser-plasma Interaction Cotton Bollworm Adapts to Bt Cotton via Diverse Mutations A Histone Acetyltransferase Regulates Active DNA Demethylation in Arabidopsis

  11. Novel research

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Author Robert Harris and film director Paul Greengrass visited CERN on 26 April, passing by SM18 as well as the CCC and the ATLAS control room.   Film director Paul Greengrass (left) and author Robert Harris (right). Author Robert Harris and film director Paul Greengrass visited CERN on 26 April as part of their preliminary research on an idea that Harris has for a book, which Greengrass might turn into a film. One of the characters would be a theoretical physicist from CERN – but to say more than that might give away the story! There is definite irony in the fact that their visit was delayed for a week by the ash from the Icelandic volcanic eruption. Harris is well known for several historical novels, including ‘Pompeii’, which tells the story of a fictional hydraulic engineer at the time of the eruption of Mount Vesuvius in 79 AD. His latest book, ‘The Ghost’, became a film directed by Roman Polanski, while the latest film from Greengrass is &a...

  12. Research Productivity and Academics' Conceptions of Research

    Science.gov (United States)

    Brew, Angela; Boud, David; Namgung, Sang Un; Lucas, Lisa; Crawford, Karin

    2016-01-01

    This paper asks the question: do people with different levels of research productivity and identification as a researcher think of research differently? It discusses a study that differentiated levels of research productivity among English and Australian academics working in research-intensive environments in three broad discipline areas: science,…

  13. Current Research Studies

    Science.gov (United States)

    ... Home > Explore CCFA Research > Current Research Studies Current Research Studies Email Print + Share The Crohn’s & Colitis Foundation ... online. Learn more about CCFA Partners. CCFA Clinical Research Alliance The Clinical Research Alliance is a network ...

  14. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library Resources Research Resources Clinical Research Resources Safety, Regulation ...

  15. Design Research between Design and Research

    DEFF Research Database (Denmark)

    Steinø, Nicolai; Markussen, Thomas

    2011-01-01

    The discourse on architecture and design research in Denmark in the past thirty years has been stuck in a unproductive dichotomy between research through design on the one hand and a phantom image of academic and theoretical, word-based research on the other. Advocates of the research through...

  16. Stories on Research, Research on Stories

    Science.gov (United States)

    Petit, Sandrine; Mougenot, Catherine; Fleury, Philippe

    2011-01-01

    This article deals with a group of researchers involved in Participatory Action Research projects on biodiversity and who volunteered to take part in a "storytelling" experiment. Their "stories" were used to describe this new type of research collective comprising various partners, including researchers and managers, focused on obtaining directly…

  17. Researching Research: Mathematics Education in the Political

    Science.gov (United States)

    Pais, Alexandre; Valero, Paola

    2012-01-01

    We discuss contemporary theories in mathematics education in order to do research on research. Our strategy consists of analysing discursively and ideologically recent key publications addressing the role of theory in mathematics education research. We examine how the field fabricates its object of research by deploying Foucault's notion of…

  18. African Primary Care Research: Participatory action research

    OpenAIRE

    Bob Mash

    2014-01-01

    Abstract This article is part of the series on African primary care research and focuses on participatory action research. The article gives an overview of the emancipatory-critical research paradigm, the key characteristics and different types of participatory action research. Following this it describes in detail the methodological issues involved in professional participatory action research and running a cooperative inquiry group. The article is intended to help students with writing thei...

  19. Doctoral Research Presentations

    OpenAIRE

    Thomson, Alison; Plummer-Fernandez, Matthew; Yurman, Paulina; Migliore, Enza; Gray, Nicola; Yang, Ya-huei; Hogan, Nicola; Kerridge, Tobie

    2015-01-01

    The Department of Design has a thriving community of scholars and practitioners engaged in doctoral research. In this session students,graduates and visiting researchers will present their research covering a broad range of topics and research interests.

  20. Architectural project and research

    DEFF Research Database (Denmark)

    Lotz, Katrine

    2005-01-01

    Discussion of criterias for research including the researchers or designers own project as theme.......Discussion of criterias for research including the researchers or designers own project as theme....

  1. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Lines Health Services Locator HealthCare.gov NIH Clinical Research Trials and You Talking to Your Doctor Science ... More » Quick Links NIH News in Health NIH Research Matters NIH Record Research & Training Medical Research Initiatives ...

  2. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Research Trials and You Community Resources Publications List Science Education Resources Talking to Your Doctor More » Search ... Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics ...

  3. Social Biography and Research.

    Science.gov (United States)

    Crepeau, Elizabeth Blesedell

    1997-01-01

    A researcher's life experiences cannot help but influence the research process. Including elements of one's social biography in research reports helps readers identify how a researcher's history and biases shaped the study. (SK)

  4. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Research Trials and You Talking to Your Doctor Science Education Resources Community Resources Publications List More » Search ... Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics ...

  5. Lymphoma Research Foundation

    Science.gov (United States)

    ... the stem cell transplantation process. Read More LYMPHOMA RESEARCH Featured Researcher – David Scott, MBChB, PhD Dr. Scott ... and Advocacy News Action Center Advocacy Tool Kit Research LRF Research Portfolio Disease-Specific Focus Areas Grants ...

  6. The modern research environment

    DEFF Research Database (Denmark)

    Topsøe, Flemming

    1993-01-01

    Information Technology, research environment, structured documents, networked information retrieval......Information Technology, research environment, structured documents, networked information retrieval...

  7. From Evaluation to Research

    Science.gov (United States)

    Arthur, Linet; Cox, Elaine

    2014-01-01

    Traditionally there has been a tension between evaluation research and so-called pure research which has resulted in evaluation research seldom being recognized by the UK Research Assessment Exercises. The newly configured Research Excellence Framework (REF) will use similar criteria to judge research, notwithstanding the introduction of…

  8. Ethical Proactive Threat Research

    Science.gov (United States)

    Aycock, John; Sullins, John

    Through a provocative examination of the positive effects of computer security research on regular users, we argue that traditional security research is insufficient. Instead, we turn to a largely untapped alternative, proactive threat research, a fruitful research area but an ethical minefield. We discuss practices for ethical research and dissemination of proactive research.

  9. Design Research between Design and Research

    DEFF Research Database (Denmark)

    Steinø, Nicolai; Markussen, Thomas

    and practice, as expressed in the notion of research as ‘artistic innovation work’. On the other hand, the pressure to expand research in architecture and design has seen a movement towards adopting traditional research paradigms from the technical and social sciences and humanities. For many architects......The discourse on architecture and design research in Denmark in the past thirty years has been stuck in a unproductive dichotomy between research through design on the one hand and a phantom image of academic and theoretical, word-based research on the other. Advocates of the research through...... design strand have argued, that architecture and design research must follow an architecture and design methodology – designing – and be communicated by means of architecture and design media – images and artefacts. Essentially, this view sees no difference between architecture and design research...

  10. From Action Research to Practice Research

    Directory of Open Access Journals (Sweden)

    Goran Goldkuhl

    2012-04-01

    Full Text Available Action research (AR has gained more acceptance as an approach to qualitative research in information systems (IS. The complexities of organisational and technical change makes this approach a suitable one in IS research. There are, however, still some controversies and confusions about the relation between “action” and “research”. The many types of AR and similar approaches (not labelled as AR that have emerged demands further conceptual clarification of AR. A conceptual inquiry of AR, presented in the paper, has led to the identification of several unresolved issues concerning intervention research like AR. An alternative research approach is presented: practice research. This research approach is well founded in pragmatism and it builds on the two premises: 1 to contribute to general practice through abstract and useful knowledge and 2 to study the empirical field as interconnected practices. Several important concepts of practice research are described as: local practice contribution vs. general practice contribution; theorizing vs. situational inquiry. Practice research is seen as a broader notion encompassing AR and other research approaches as e.g. design research and evaluation research. Two case examples of practice research are briefly presented and compared: one AR-based study in the social welfare sector and one evaluation study of a taxation e-service.

  11. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, N., E-mail: nbertell@pppl.gov; Gerhardt, S.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Taylor, G.; Valeo, E. J.; Wilson, J. R. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Jaeger, E. F. [XCEL Engineering Inc., Oak Ridge, TN 37830 (United States); Lau, C.; Blazevski, D.; Green, D. L.; Berry, L.; Ryan, P. M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Bonoli, P. T.; Wright, J. C. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Pinsker, R. I.; Prater, R. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Qin, C. M. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); and others

    2015-12-10

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to “conventional” tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  12. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, Nicola [Princeton Plasma Physics Laboratory (PPPL); Jaeger, E. F. [XCEL Engineering Inc., Oak Ridge; Lau, Cornwall H [ORNL; Blazevski, Dan [Oak Ridge National Laboratory (ORNL); Berry, Lee Alan [XCEL Engineering Inc., Oak Ridge; Bonoli, P. T. [Massachusetts Institute of Technology (MIT); Gerhardt, S.P. [Princeton Plasma Physics Laboratory (PPPL); Hosea, J. C. [Princeton Plasma Physics Laboratory (PPPL); LeBlanc, B. [Princeton Plasma Physics Laboratory (PPPL); Perkins, R. J. [Princeton Plasma Physics Laboratory (PPPL); Phillips, Cynthia [Princeton Plasma Physics Laboratory (PPPL); Pinsker, R. I. [General Atomics, San Diego; Prater, R. [General Atomics; Qin, C M [Chinese Academy of Sciences (CAS), Institute of Plasma Physics, Hefei; Ryan, P. M. [Oak Ridge National Laboratory (ORNL); Taylor, G. [Princeton Plasma Physics Laboratory (PPPL); Valeo, E. J. [Princeton Plasma Physics Laboratory (PPPL); Wilson, Randy [Princeton Plasma Physics Laboratory (PPPL); Wright, J. [Massachusetts Institute of Technology (MIT); Zhang, X J [Chinese Academy of Sciences (CAS), Institute of Plasma Physics, Hefei

    2015-01-01

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to "conventional" tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  13. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    Science.gov (United States)

    Bertelli, N.; Jaeger, E. F.; Lau, C.; Blazevski, D.; Green, D. L.; Berry, L.; Bonoli, P. T.; Gerhardt, S.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Pinsker, R. I.; Prater, R.; Qin, C. M.; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Wright, J. C.; Zhang, X. J.

    2015-12-01

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to "conventional" tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  14. Research Identities: Reflections of a Contract Researcher

    OpenAIRE

    Jackie Goode

    2006-01-01

    This paper examines the institutional identity formation of contract research staff in the context of the Taylorisation of research knowledges. The author has been a contract researcher for many years, after initially training and practising as a Probation Officer. She makes links between her social work training, and her current practice as a qualitative researcher. Drawing on her experience of working on a variety of different projects, at a number of different institutions, and providing i...

  15. Case Study Research Methodology in Nursing Research.

    Science.gov (United States)

    Cope, Diane G

    2015-11-01

    Through data collection methods using a holistic approach that focuses on variables in a natural setting, qualitative research methods seek to understand participants' perceptions and interpretations. Common qualitative research methods include ethnography, phenomenology, grounded theory, and historic research. Another type of methodology that has a similar qualitative approach is case study research, which seeks to understand a phenomenon or case from multiple perspectives within a given real-world context.

  16. An Open Research University

    OpenAIRE

    Holliman, Richard; Adams, Anne; BLACKMAN, TIM; Collins, Trevor; Davies, Gareth; Dibb, Sally; Grand, Ann; Holti, Richard; Mckerlie, Fiona; Mahony, Nick; Wissenburg, Astrid

    2015-01-01

    This is the final report of the Open University’s RCUK-funded Public Engagement with Research Catalyst, ‘An open research university’, a project designed to create the conditions in which engaged research can flourish. The report describes an evidence-based strategy designed to embed engaged research within the University’s strategic planning for research and the operational practices of researchers. This programme of organisational change was informed by action research, working collaborat...

  17. Research Leadership as Entrepreneurial Organizing for Research

    Science.gov (United States)

    Hansson, Finn; Monsted, Mette

    2008-01-01

    The paper discusses research leadership in public universities under change and the role of entrepreneurial strategies in research. Research leadership function today in situations where the New Public Management movement one the one hand have introduced management by accountability and control in the university while on the other hand open…

  18. Research Supervision: The Research Management Matrix

    Science.gov (United States)

    Maxwell, T. W.; Smyth, Robyn

    2010-01-01

    We briefly make a case for re-conceptualising research project supervision/advising as the consideration of three inter-related areas: the learning and teaching process; developing the student; and producing the research project/outcome as a social practice. We use this as our theoretical base for an heuristic tool, "the research management…

  19. Research reactors and alternative devices for research

    International Nuclear Information System (INIS)

    This report includes papers on research reactors and alternatives to the research reactors - radioisotopic neutron sources, cyclotrons, D-T neutron generators and small accelerators, used for radioisotope production, neutron activation analysis, material science, applied and basic research using neutron beams. A separate abstract was prepared for each of the 7 papers

  20. Teacher as Researcher: Teaching as Lived Research

    Science.gov (United States)

    Binder, Marni

    2012-01-01

    Teacher inquiry can shape empirical inquiries by nonpracticing researchers, by allowing them to draw on the practical knowledge of those in the classroom. This recognition challenged the author to question what legitimized her role as a teacher-researcher and ask how she could have felt empowered as a researcher without higher education. In this…

  1. Nuclear research reactors

    International Nuclear Information System (INIS)

    It's presented data about nuclear research reactors in the world, retrieved from the Sien (Nuclear and Energetic Information System) data bank. The information are organized in table forms as follows: research reactors by countries; research reactors by type; research reactors by fuel and research reactors by purpose. (E.G.)

  2. Nuclear energy related research

    Science.gov (United States)

    Rintamaa, R.

    1992-05-01

    The annual Research Program Plan describes publicly funded nuclear energy related research to be carried out mainly at the Technical Research Center of Finland (VTT) in 1992. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Center for Radiation and Nuclear Safety (STUK), and VTT itself. Other research institutes, utilities, and industry also contribute to many projects.

  3. Nuclear energy related research

    International Nuclear Information System (INIS)

    The annual Research Programme Plan describes the publicly funded nuclear energy related research to be carried out mainly at the Technical Research Centre of Finland (VTT) in 1991. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Other research institutes, utilities and industry also contribute to many projects

  4. Nuclear energy related research

    International Nuclear Information System (INIS)

    The annual Research Programme Plan describes publicly funded nuclear energy related research to be carried out mainly at the Technical Research Centre of Finland (VTT) in 1992. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Other research institutes, utilities and industry also contribute to many projects

  5. From Research Assistant to Professional Research Assistance: Research Consulting as a Form of Research Practice

    Science.gov (United States)

    Pollon, Dawn E.; Herbert, Monique; Chahine, Saad; Falenchuk, Olesya

    2013-01-01

    Research assistantships have long been viewed as an extension of the formal education process, a form of apprenticeship, and a pathway into the professional practice of research in institutional settings. However, there are other contexts in which researchers practice research. This self-study documents the formative role research assistantships…

  6. From Research Assistant to Professional Research Assistance: Research Consulting as a Form of Research Practice

    Directory of Open Access Journals (Sweden)

    Dawn E. Pollon

    2013-01-01

    Full Text Available Research assistantships have long been viewed as an extension of the formal education process, a form of apprenticeship, and a pathway into the professional practice of research in institutional settings. However, there are other contexts in which researchers practice research. This self-study documents the formative role research assistantships played in the authors’ development as professional research consultants. Four professional research consultants who held research assistant positions during their master’s and doctoral studies describe the contributions of their research assistantship experiences to the advancement of their knowledge, skills, and passion for research and subsequently to their career decisions. Professional research consulting is identified as a natural extension of research assistant roles and a potential career path. The article enhances current understandings about the ways research assistantships contribute to the development of researchers, and specifically to the development of professional research consultants. The analysis will be of interest to students contemplating entering into research assistantships, current research assistants, current research assistant supervisors, academic staff looking to improve their research productivity, and department chairs.

  7. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Trials and You Community Resources Publications List Science Education Resources Talking to Your Doctor More » Search Health ... Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library ...

  8. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Science Education Research in NIH Labs & Clinics Training Opportunities Library Resources Research Resources Clinical Research Resources Safety, ... About NIH Who We Are What We Do Jobs at NIH Visitor Information Frequently Asked Questions Contact ...

  9. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Trials and You Talking to Your Doctor Science Education Resources Community Resources Publications List More » Search Health ... Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library ...

  10. Dystonia Medical Research Foundation

    Science.gov (United States)

    ... of Dystonia Research Research News Funding Programs Current Research Dystonia Coalition About DMRF Mission People Dystonia Dialogue Financials For the Media Connect Contact Us Privacy Policy Support Groups Calendar

  11. Research Advocacy at NCI

    Science.gov (United States)

    The patient perspective research advocates brings into NCI’s research enterprise helps to inform research focus and support the dissemination of results that lead to new and better cancer prevention, detection, and treatment methods.

  12. Research on Catalysis.

    Science.gov (United States)

    Bartholomew, Calvin H.; Hecker, William C.

    1984-01-01

    The objectives and philosophy of the Catalysis Laboratory at Brigham Young University are discussed. Also discusses recent and current research activities at the laboratory as well as educational opportunities, research facilities, and sources of research support. (JN)

  13. National Privacy Research Strategy

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — On July 1, NITRD released the National Privacy Research Strategy. Research agencies across government participated in the development of the strategy, reviewing...

  14. Glaucoma Research Foundation

    Science.gov (United States)

    ... Surgery Find an Eye Doctor Financial Assistance New Research Results We invest in research to find a cure for glaucoma. The Biomarker ... Drake Hotel honored GRF's founders and featured a research update from Dr. Jeff Goldberg. Glaucoma in the ...

  15. Research Areas: Liver Disease

    Science.gov (United States)

    ... 900 drugs and supplements.​​ Recent discoveries from NIDDK research include: New medication shows promise against liver fibrosis ... linked to biliary atresia in newborn animals Support Research NIDDK invests in basic, clinical and translational research ...

  16. [Memorandum prevention research - research areas and methods].

    Science.gov (United States)

    Walter, U; Nöcker, G; Plaumann, M; Linden, S; Pott, E; Koch, U; Pawils, S; Altgeld, T; Dierks, M L; Frahsa, A; Jahn, I; Krauth, C; Pomp, M; Rehaag, R; Robra, B P; Süß, W; Töppich, J; Trojan, A; von Unger, H; Wildner, M; Wright, M

    2012-10-01

    From 2004 to 2012, the German Ministry of Education and Research (BMBF) established its first funding programme for the promotion of prevention research. 60 projects on primary prevention and health promotion and the meta-project entitled "Cooperation for Sustainable Prevention Research" (KNP) received BMBF grants under this programme during this period. The experience and knowledge gained and recommendations arising from the research funded under this programme are compiled in memorandum format. The "Memorandum on Prevention Research - Research Areas and Methods" highlights 5 research areas that are considered to be especially relevant from the perspective of the involved scientists and practice partners.The promotion of structural development and sustainability enhancement in disease prevention and health promotion are central areas that should branch out from existing nuclei of crystallization. Improving the health competence of the population and of specific subpopulations is another major area. Research in these areas should contribute to the development of theoretical concepts and to the empirical testing of these concepts. The transfer of knowledge for effective use of developed disease prevention and health promotion programmes and measures is still a scarcely researched area. Among other things, studies of the transfer of programmes from one context to another, analyses of the coop-eration between politics and science, and the continued theoretical and conceptual development of transfer research are needed. Long-term data on the effects of intervention studies are also needed for proper evaluation of sustainability. The latter dem-onstrates the importance of method development in disease prevention and health promotion research as an area that should receive separate funding and support. This research should include, in particular, studies of the efficacy of complex interventions, health economic analyses, and participative health research. PMID:23165608

  17. Final Technical Report -- Bridging the PSI Knowledge Gap: A Multiscale Approach

    Energy Technology Data Exchange (ETDEWEB)

    Whyte, Dennis [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2014-12-12

    The Plasma Surface Interactions (PSI) Science Center formed by the grant undertook a multidisciplinary set of studies on the complex interface between the plasma and solid states of matter. The strategy of the center was to combine and integrate the experimental, diagnostic and modeling toolkits from multiple institutions towards specific PSI problems. In this way the Center could tackle integrated science issues which were not addressable by single institutions, as well as evolve the underlying science of the PSI in a more general way than just for fusion applications. The overall strategy proved very successful. The research result and highlights of the MIT portion of the Center are primarily described. A particular highlight is the study of tungsten nano-tendril growth in the presence of helium plasmas. The Center research provided valuable new insights to the mechanisms controlling the nano-tendrils by developing coupled modeling and in situ diagnostic methods which could be directly compared. For example, the role of helium accumulation in tungsten distortion in the surface was followed with unique in situ helium concentration diagnostics developed. These depth-profiled, time-resolved helium concentration measurements continue to challenge the numerical models of nano-tendrils. The Center team also combined its expertise on tungsten nano-tendrils to demonstrate for the first time the growth of the tendrils in a fusion environment on the Alcator C-Mod fusion experiment, thus having significant impact on the broader fusion research effort. A new form of isolated nano-tendril “columns” were identified which are now being used to understand the underlying mechanisms controlling the tendril growth. The Center also advanced PSI science on a broader front with a particular emphasis on developing a wide range of in situ PSI diagnostic tools at the DIONISOS facility at MIT. For example the strong suppression of sputtering by the certain combination of light

  18. RESEARCH APPROACH: AN OVERVIEW

    OpenAIRE

    Vijay Kumar Grover

    2015-01-01

    The paper attempts to explain different possible research approaches to pursue a research project. It starts with three important components of a research approach amelyphilosophical world view, research design, and research methods. Research approaches are classified on the basis of work of Guba (1990), which puts it in to the categories of post positivism, constructivism, transformative and pragmatism. Further paper explains salient features and principals of these four world views. ...

  19. Research on Tourism

    OpenAIRE

    Špačková, Martina

    2009-01-01

    The thesis acquaints with issues and problems of research on tourism, summarizes existing knowledge and development of this theme. It also addresses the issue of institutional, legislative and financial security of research in the Czech Republic (research in general and specifically research on tourism) and the current problems with which the research on tourism meets in the Czech Republic. The thesis also maps out the research activities of some foreign institutions and organizations. Part o...

  20. High Combustion Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL's High-Pressure Combustion Research Facility in Morgantown, WV, researchers can investigate new high-pressure, high-temperature hydrogen turbine combustion...

  1. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Research & Training Medical Research Initiatives Science Highlights Science ... & Offices NIH Office of the Director Directors of NIH Institutes and Centers Mailing Addresses ...

  2. Fuel safety research 1999

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-07-01

    In April 1999, the Fuel Safety Research Laboratory was newly established as a result of reorganization of the Nuclear Safety Research Center, JAERI. The laboratory was organized by combining three laboratories, the Reactivity Accident Laboratory, the Fuel Reliability Laboratory, and a part of the Sever Accident Research Laboratory. Consequently, the Fuel Safety Research Laboratory is now in charge of all the fuel safety research in JAERI. Various types of experimental and analytical researches are conducted in the laboratory by using the unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and hot cells in JAERI. The laboratory consists of five research groups corresponding to each research fields. They are; (a) Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). (b) Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). (c) Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). (d) Research group of fuel behavior analysis (FEMAXI group). (e) Research group of FP release/transport behavior from irradiated fuel (VEGA group). This report summarizes the outline of research activities and major outcomes of the research executed in 1999 in the Fuel Safety Research Laboratory. (author)

  3. Research at KT 2002

    DEFF Research Database (Denmark)

    Glarborg, Peter; Hassager, Ole; Jonsson, Gunnar Eigil;

    2002-01-01

    The objective of this document is to give the reader a brief overview of current research directions at the department of chemical engineering. The main research topics are classified in terms of priority research areas and are achievements in these areas are highlighted through publications made...... by the 6 main research groups. It should be noted, however, the listed research topics are not the only areas of research and that there are also other interdisciplinary research groups and individual faculty members with their specific research area....

  4. National Environmental Research Parks

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The National Environmental Research Parks are outdoor laboratories that provide opportunities for environmental studies on protected lands that act as buffers around Department of Energy (DOE) facilities. The research parks are used to evaluate the environmental consequences of energy use and development as well as the strategies to mitigate these effects. They are also used to demonstrate possible environmental and land-use options. The seven parks are: Fermilab National Environmental Research Park; Hanford National Environmental Research Park; Idaho National Environmental Research Park; Los Alamos National Environmental Research Park; Nevada National Environmental Research Park; Oak Ridge National Environmental Research Park; and Savannah River National Environmental Research Park. This document gives an overview of the events that led to the creation of the research parks. Its main purpose is to summarize key points about each park, including ecological research, geological characteristics, facilities, and available databases.

  5. Fusion Energy Science Joint Facilities and Theory Research Target 2011: Final Report for the Period October 1, 2010 through September 30, 2011

    Energy Technology Data Exchange (ETDEWEB)

    Groebner, R. J. [General Atomics, La Jolla, CA (United States); Chang, C. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Diamond, P. H. [Univ. of California, San Diego, CA (United States); Hughes, J. W. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Maingi, R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Snyder, P. B. [General Atomics, La Jolla, CA (United States); Xu, X. Q. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-10-01

    Briefly stated, the goal of this combined experiment/theory milestone was to improve our knowledge of the physics processes that control the H-mode pedestal by applying models of these mechanisms to experimental data. A concerted and coordinated effort of experimental, theory and modeling activities has examined several physics mechanisms of interest, and has met the goals of the milestone. A few noteworthy results will be noted here. The activity has applied peeling-ballooning theory to all three machines, and increased confidence that the theory predicts the ultimate limits to pedestal height in an ELMing plasma. The activity has expanded the range of conditions for testing of the EPED model, and increased confidence in the ability of the model to compute the pedestal pressure height in medium aspect ratio tokamaks. Kinetic neoclassical models have been used to verify that an important analytic model for the pedestal bootstrap current has good accuracy in many regimes of interest but needs correction at high collisionality. A benchmarking effort between electromagnetic gyrokinetic codes has provided increased understanding of how to use these codes in the pedestal, and has laid the groundwork for using these codes to study linear stability of gyrokinetic modes in and on top of the pedestal. Comparisons of data and models have led to successful simulations of a quasi-coherent mode in C-Mod and to the tentative identification of a high frequency mode in DIII-D. A kinetic neoclassical model qualitatively agrees with some features of pedestal density profiles. A paleoclassical transport model quantitatively predicts some features of the electron temperature profiles in NSTX and DIII-D. The milestone activity also laid the groundwork for future advancements in understanding and predicting the pedestal. All three machines obtained a wealth of pedestal data under a wide variety of operating conditions. Some of these data have been analyzed already, and the analysis and

  6. Fusion Energy Science Joint Facilities and Theory Research Target 2011: Final Report for the Period October 1, 2010 through September 30, 2011

    Energy Technology Data Exchange (ETDEWEB)

    Groebner, R. J. [General Atomics, La Jolla, CA (United States); Chang, C. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Diamond, P. H. [Univ. of California, San Diego, CA (United States); Hughes, J. W. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Maingi, R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Snyder, P. B. [General Atomics, La Jolla, CA (United States); Xu, X. Q. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-10-01

    Briefly stated, the goal of this combined experiment/theory milestone was to improve our knowledge of the physics processes that control the H-mode pedestal by applying models of these mechanisms to experimental data. A concerted and coordinated effort of experimental, theory and modeling activities has examined several physics mechanisms of interest and has met the goals of the milestone. A few noteworthy results will be noted here. The activity has applied peeling-ballooning theory to all three machines and increased confidence that the theory predicts the ultimate limits to pedestal height in an ELMing plasma. The activity has expanded the range of conditions for testing of the EPED model and increased confidence in the ability of the model to compute the pedestal pressure height in medium aspect ratio tokamaks. Kinetic neoclassical models have been used to verify that an important analytic model for the pedestal bootstrap current has good accuracy in many regimes of interest but needs correction at high collisionality. A benchmarking effort between electromagnetic gyrokinetic codes has provided increased understanding of how to use these codes in the pedestal and has laid the groundwork for using these codes to study linear stability of gyrokinetic modes in and on top of the pedestal. Comparisons of data and models have led to successful simulations of a quasi-coherent mode in C-Mod and to the tentative identification of a high frequency mode in DIII-D. A kinetic neoclassical model qualitatively agrees with some features of pedestal density profiles. A paleoclassical transport model quantitatively predicts some features of the electron temperature profiles in NSTX and DIII-D. The milestone activity also laid the groundwork for future advancements in understanding and predicting the pedestal. All three machines obtained a wealth of pedestal data under a wide variety of operating conditions. Some of these data have been analyzed already and the analysis and

  7. Nuclear energy related research

    International Nuclear Information System (INIS)

    The annual Research Programme Plan describes the publicly funded nuclear energy related research to be carried out at the Technical Research Centre of Finland (VTT) in 1990. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Utilities and industry also contribute to some projects

  8. Research Methods Tutorial

    Science.gov (United States)

    Aguilera, Frank J.

    2015-01-01

    A guiding principle for conducting research in technology, science, and engineering, leading to innovation is based on our use of research methodology (both qualitative and qualitative). A brief review of research methodology will be presented with an overview of NASA process in developing aeronautics technologies and other things to consider in research including what is innovation.

  9. Australian Research Council

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Introduction The Australian Research Council(ARC) is the Australian Government's main agency for allocating research funding to academics and researchers in Australian universities.Its mission is to deliver policy and programs that advance Australian research and innovation globally and benefit the community.

  10. Teaching to Enhance Research

    Science.gov (United States)

    Harland, Tony

    2016-01-01

    In this paper, I present a conceptual argument for "teaching-led research" in which university lecturers construct courses that directly and positively influence their research, while at the same time, safeguard and enhance the student experience. A research-pedagogy for higher education considers the link between teaching and research,…

  11. The Integrity of Research

    Science.gov (United States)

    Axman, Linnea; Boren, Denise

    2010-01-01

    This text is the foundation from which a distinguished lecture was developed focusing on the necessity for research in healthcare carried out with attention to issues of integrity, the hallmark of all commendable research. A cautionary historical review of research misconduct and related topics is provided. Research within a cultural context and…

  12. Effectively Communicating Qualitative Research

    Science.gov (United States)

    Ponterotto, Joseph G.; Grieger, Ingrid

    2007-01-01

    This article is a guide for counseling researchers wishing to communicate the methods and results of their qualitative research to varied audiences. The authors posit that the first step in effectively communicating qualitative research is the development of strong qualitative research skills. To this end, the authors review a process model for…

  13. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Act News & Events News Releases Videos Images Events Social Media & Outreach More » Quick Links NIH News in Health NIH Research Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics ...

  14. Nuclear energy related research

    International Nuclear Information System (INIS)

    This annual Research Programme Plan covers the publicly funded nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1989. The research will be financed by the Ministry of Trade and Industry, the Finnish Centre for Radiation and Nuclear Safety, the Nordic Council of Ministers and VTT itself

  15. Nuclear energy related research

    International Nuclear Information System (INIS)

    This annual Research Programme Plan covers the publicly funded nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1988. The research will be financed by the Ministry of Trade and Industry, the Finnish Centre for Radiation and Nuclear Safety, the Nordic Council of Ministers and VTT itself

  16. Educational Researchers and Practicality

    Science.gov (United States)

    Van Velzen, Joke H.

    2013-01-01

    In this article, an attempt to identify further directions in research designs that researchers can use to contribute to the relevance of educational research findings, by including teachers' practicality issues, is presented. Sixty experienced teachers in secondary education read the reporting of modified experimental research findings about…

  17. Research Data Management - Handouts

    OpenAIRE

    Collins, Anna

    2012-01-01

    This is a series of handouts that can be used to assist researchers with data management. They are all available under a CC-BY-NC-SA license. The forms include: Defining Digital Research Data, Drafting a Data Management Plan in Reverse, File Formats - text files, Research Projects: File Structure & Naming and Data Management Plan for Research Projects

  18. Lower hybrid current ramp-up experiments and density limit on Alcator C

    International Nuclear Information System (INIS)

    Lower hybrid plasma current ramp-up efficiencies at densities n-bar/sub e/> or =1 x 1013 cm-3 are investigated. The ramp-up efficiency P/sub e//sub l//P/sub r//sub f/ of almost 100% is obtained shortly after the rf turn on, but the efficiency drops to typically 5-10% after this initial transient which dies away in about 50ms. The cut-off density for electron tail formation was also investigated. It correlated with the onset of parametric decay and ion tail formation near the plasma edge. However, at high magnetic fields and high plasma currents (B = 10T, l/sub p/ = 0.5MA, H plasma) an ion tail was observed even below the parametric threshold density

  19. Numerical modelling of lower hybrid RF heating and current drive experiments in the Alcator C tokamak

    International Nuclear Information System (INIS)

    A simulation model is described for lower hybrid (LH) current drive, rampup, heating, and sawtooth stabilization. The model incorporates a one-dimensional radial transport code, parallel velocity Fokker-Planck calculation, and a toroidal ray tracing code. For steady LH current drive it is found that the RF current generation is accurately predicted by a fast electron confinement time of the form τL=τ0(±)γ3, with τ0(±)=3ms in the density range of 3x1019m-3 e 19m-3 (where ± distinguishes electrons moving parallel (antiparallel) to the current drive direction). Also in this range, the theoretically predicted wave absorption and experimentally measured electron temperatures and stored energy were found to be consistent with an electron thermal diffusivity whose magnitude is independent of ne. To reproduce the experimentally measured values of LH rampup efficiency at n-bare=3x1019m-3, it was necessary to take τ0(±)=3ms. For LH heating at densities of n-bare approx.= 1.4x1020m-3, the power lost due to collisional damping of the LH ray trajectories at the plasma periphery was found to be significant, because of higher edge densities. Studies of LHRF sawtooth stabilization experiments with RF current drive indicated the possibility of creating stable profiles of the safety factor, q, via the generation of positive RF current near the q=1 surface, thus producing a current 'pedestal'. (author). 41 refs, 13 figs, 3 tabs

  20. Active and fast particle driven Alfvén eigenmodes in Alcator C-Moda)

    Science.gov (United States)

    Snipes, J. A.; Basse, N.; Boswell, C.; Edlund, E.; Fasoli, A.; Gorelenkov, N. N.; Granetz, R. S.; Lin, L.; Lin, Y.; Parker, R.; Porkolab, M.; Sears, J.; Sharapov, S.; Tang, V.; Wukitch, S.

    2005-05-01

    Alfvén eigenmodes (AEs) are studied to assess their stability in high density reactor relevant regimes where Ti≈Te and as a diagnostic tool. Stable AEs are excited with active magnetohydrodynamics antennas in the range of the expected AE frequency. Toroidal Alfvén eigenmode (TAE) damping rates between 0.5%<γ/ω<4.5% have been observed in diverted and limited Ohmic plasmas. Unstable AEs are excited with a fast ion tail driven by H minority ion cyclotron radio frequency (ICRF) heating with electron densities in the range of n¯e=0.5-2×1020m-3. Energetic particle modes or TAEs have been observed to decrease in frequency and mode number with time up to a large sawtooth collapse, indicating the role fast particles play in stabilizing sawteeth. In the current rise phase, unstable modes with frequencies that increase rapidly with time are observed with magnetic pick-up coils at the wall and phase contrast imaging density fluctuation measurements in the core. Modeling of these modes constrains the calculated safety factor profile to be very flat or with slightly reversed shear. AEs are found to be more stable for an inboard than for central or outboard ICRF resonances in qualitative agreement with modeling.

  1. Critical gradients and plasma flows in the edge plasma of Alcator C-Moda)

    Science.gov (United States)

    Labombard, B.; Hughes, J. W.; Smick, N.; Graf, A.; Marr, K.; McDermott, R.; Reinke, M.; Greenwald, M.; Lipschultz, B.; Terry, J. L.; Whyte, D. G.; Zweben, S. J.; Alcator C-Mod Team

    2008-05-01

    Recent experiments have led to a fundamental shift in our view of edge transport physics; transport near the last-closed flux surface may be more appropriately described in terms of a critical gradient phenomenon rather than a diffusive and/or convective paradigm. Edge pressure gradients, normalized by the square of the poloidal magnetic field strength, appear invariant in plasmas with the same normalized collisionality, despite vastly different currents and magnetic fields—a behavior that connects with first-principles electromagnetic plasma turbulence simulations. Near-sonic scrape-off layer (SOL) flows impose a cocurrent rotation boundary condition on the confined plasma when B ×∇B points toward the active x-point, suggesting a link to the concomitant reduction in input power needed to attain high-confinement modes. Indeed, low-confinement mode plasmas are found to attain higher edge pressure gradients in this configuration, independent of the direction of B, evidence that SOL flows may affect transport and "critical gradient" values in the edge plasma.

  2. Wide-view charge exchange recombination spectroscopy diagnostic for Alcator C-Moda)

    Science.gov (United States)

    Rowan, W. L.; Bespamyatnov, I. O.; Granetz, R. S.

    2008-10-01

    This diagnostic measures temperature, density, and rotation for the fully stripped boron ion between the pedestal top and the plasma core with resolution consistent with the profile gradients. The diagnostic neutral beam used for the measurements generates a 50 keV, 6 A hydrogen beam. The optical systems provide views in both poloidal and toroidal directions. The imaging spectrometer is optimized to simultaneously accept 45 views as input with minimum cross-talk. In situ calibration techniques are applied for spatial location, spectral intensity, and wavelength. In the analysis, measured spectra are fitted to a model constructed from a detailed description of the emission physics. Methods for removal of interfering spectra are included. Applications include impurity and thermal transport.

  3. Scaling of the power exhaust channel in Alcator C-Moda)

    Science.gov (United States)

    LaBombard, B.; Terry, J. L.; Hughes, J. W.; Brunner, D.; Payne, J.; Reinke, M. L.; Cziegler, I.; Granetz, R.; Greenwald, M.; Hutchinson, I. H.; Irby, J.; Lin, Y.; Lipschultz, B.; Ma, Y.; Marmar, E. S.; Rowan, W. L.; Tsujii, N.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Wurden, G.; Team, Alcator C-Mod

    2011-05-01

    Parametric dependences of the heat flux footprint on the outer divertor target plate are explored in EDA H-mode and ohmic L-mode plasmas over a wide range of parameters with attached plasma conditions. Heat flux profile shapes are found to be independent of toroidal field strength, independent of power flow along magnetic field lines and insensitive to x-point topology (single-null versus double-null). The magnitudes and widths closely follow that of the "upstream" pressure profile, which are correlated to plasma thermal energy content and plasma current. Heat flux decay lengths near the strike-point in H- and L-mode plasmas scale approximately with the inverse of plasma current, with a diminished dependence at high collisionality in L-mode. Consistent with previous studies, pressure gradients in the boundary scale with plasma current squared, holding the magnetohydrodynamic ballooning parameter approximately invariant at fixed collisionality—strong evidence that critical-gradient transport physics plays a key role in setting the power exhaust channel.

  4. Storytelling as Research/Research as Storytelling

    Science.gov (United States)

    Lewis, Patrick J.

    2011-01-01

    If story is central to human meaning why, in the research world, is there not more storytelling? Walter Benjamin (1973) noted that, "a story is different. It does not expend itself. It preserves and concentrates its strength and is capable of releasing it even after a long time" (p. 90). How might research not expend itself, but preserve and…

  5. Teaching Qualitative Research to Practitioner-Researchers

    Science.gov (United States)

    Cox, Rebecca D.

    2012-01-01

    Practitioner-researchers are well-positioned to apply qualitative methods to the study of significant problems of educational practice. However, while learning the skills of qualitative inquiry, practitioners may be compelled by forces outside of qualitative research classrooms to think quantitatively. In this article, the author considers two…

  6. Researching as an Enactivist Mathematics Education Researcher

    Science.gov (United States)

    Brown, Laurinda

    2015-01-01

    This paper focusses on how researching is done through reflections about, or at a meta-level to, the practice over time of an enactivist mathematics education researcher. How are the key concepts of enactivist theory ("ZDM Mathematics Education," doi: 10.1007/s11858-014-0634-7, 2015) applied? This paper begins by giving an…

  7. Research essentials. How to critique quantitative research.

    Science.gov (United States)

    Clarke, Sharon; Collier, Sue

    2015-11-01

    QUANTITATIVE RESEARCH is a systematic approach to investigating numerical data and involves measuring or counting attributes, that is quantities. Through a process of transforming information that is collected or observed, the researcher can often describes a situation or event, answering the 'what' and 'how many' questions about a situation ( Parahoo 2014 ).

  8. Stimulating translational research

    DEFF Research Database (Denmark)

    Bentires-Alj, Mohamed; Rajan, Abinaya; van Harten, Wim;

    2015-01-01

    Translational research leaves no-one indifferent and everyone expects a particular benefit. We as EU-LIFE (www.eu-life.eu), an alliance of 13 research institutes in European life sciences, would like to share our experience in an attempt to identify measures to promote translational research with...... without undermining basic exploratory research and academic freedom.......Translational research leaves no-one indifferent and everyone expects a particular benefit. We as EU-LIFE (www.eu-life.eu), an alliance of 13 research institutes in European life sciences, would like to share our experience in an attempt to identify measures to promote translational research...

  9. Improving University Research Value

    Directory of Open Access Journals (Sweden)

    Kelley O’Reilly

    2012-07-01

    Full Text Available This article investigates the current data management practices of university researchers at an Intermountain West land-grant research university in the United States. Key findings suggest that researchers are primarily focused on the collection and housing of research data. However, additional research value exists within the other life cycle stages for research data—specifically in the stages of delivery and maintenance. These stages are where most new demands and requirements exist for data management plans and policies that are conditional for external grant funding; therefore, these findings expose a “gap” in current research practice. These findings should be of interest to academics and practitioners alike as findings highlight key management gaps in the life cycle of research data. This study also suggests a course of action for academic institutions to coalesce campus-wide assets to assist researchers in improving research value.

  10. Ames Research Center Research and Technology 2000

    Science.gov (United States)

    2002-01-01

    This report highlights the challenging work accomplished during fiscal year 2000 by Ames research scientists,engineers, and technologists. It discusses research and technologies that enable the Information Age, that expand the frontiers of knowledge for aeronautics and space, and that help to maintain U.S. leadership in aeronautics and space research and technology development. The accomplishments are grouped into four categories based on four of NASA's Strategic Enterprises: Aerospace Technology, Space Science, Biological and Physical Research, and Earth Science. The primary purpose of this report is to communicate knowledge-to inform our stakeholders, customer, and partners, and the people of the United States about the scope and diversity of Ames' mission,the nature of Ames' research and technolog) activities,and the stimulating challenges ahead. The accomplishments cited illustrate the contributions that Ames is willing to improve the quality of life for our citizens and the economic position of the United States in the world marketplace.

  11. Children's participation in research

    DEFF Research Database (Denmark)

    Broström professor m.so., Stig

    2012-01-01

    and research in their own preschool settings. This article offers an argument based on theory and practical examples for the inclusion of children in educational and educational research. It also introduces some of the problems which warrant consideration if researchers are to understand and cooperate...... with children as co-researchers. The author 15 portrays the educational process and the research process as a possible way for the democratisation of children....

  12. Research in Public Relations

    OpenAIRE

    Coriolan PĂUNESCU

    2006-01-01

    Research has an important role in public relations (PR) being necessary in developing strategies in this area. Therefore, we can speak of two types of research, the applied research and theoretical research, both being successfully used in the work of public relations. Applied research, can be strategic (used in programs in order to identify attitudes and opinions of the target public, to develop strategies for formulating and transmitting messages, to establish the criteria for evaluating th...

  13. FORMAS AND CLIMATE RESEARCH

    OpenAIRE

    Sellberg, В.

    2006-01-01

    Formas has the mandate from the Swedish Government to coordinate Swedish Climate Research. Within the framework of this mandate, Formas together with several other research funding agencies has published two reports, 2002 and 2003 [1, 2] in which the most important research areas are identified. In these reports, the Swedish activities in the field were mapped and new important research activities were suggested. In addition, an analysis of ongoing international research was performed. At the...

  14. Research Areas in Literature

    OpenAIRE

    Dr. S. T. Waghmode

    2012-01-01

    Research is the most distinguished activity that enhances the quality of higher-education. A person obsessed with research has to face many problems. Apart from having an appropriate guide, the real problem begins with the selection of the research topic. The vast and gleaming research area is always changing its dimensions. Some well-set, readymade and stereotyped topics do not attract the attention of a competent researcher, because he or she is always looking for what is new and qualitativ...

  15. Qualitative Research Process

    OpenAIRE

    Dewan Mahboob HOSSAIN

    2011-01-01

    This article provides with an overview of the qualitative research methods. Over last few decades, qualitative research is getting very popular in the fields of business, sociology, psychology and others. This article, in its introduction, gives a general idea about the qualitative research. Then it discusses the main differences between qualitative and quantitative research methods. The article also discusses about the ethical issues important for qualitative research. Lastly it discusses ab...

  16. Research Learning on English

    Institute of Scientific and Technical Information of China (English)

    陈媛媛; 尹静; 岳艳岭

    2016-01-01

    The research learning is to select and define research topics, initiative to acquire knowledge, application of knowledge in research, problem-solving learning activities from nature, society and life. Research learning has been widely present in students life. Research study aims to develop the students' enthusiasm, initiative development of students' personality and so on, they all plays a crucial role for the right to develop a scientific attitude.

  17. Rigour in quantitative research.

    Science.gov (United States)

    Claydon, Leica Sarah

    2015-07-22

    This article which forms part of the research series addresses scientific rigour in quantitative research. It explores the basis and use of quantitative research and the nature of scientific rigour. It examines how the reader may determine whether quantitative research results are accurate, the questions that should be asked to determine accuracy and the checklists that may be used in this process. Quantitative research has advantages in nursing, since it can provide numerical data to help answer questions encountered in everyday practice.

  18. The qualitative research proposal.

    Science.gov (United States)

    Klopper, H

    2008-12-01

    Qualitative research in the health sciences has had to overcome many prejudices and a number of misunderstandings, but today qualitative research is as acceptable as quantitative research designs and is widely funded and published. Writing the proposal of a qualitative study, however, can be a challenging feat, due to the emergent nature of the qualitative research design and the description of the methodology as a process. Even today, many sub-standard proposals at post-graduate evaluation committees and application proposals to be considered for funding are still seen. This problem has led the researcher to develop a framework to guide the qualitative researcher in writing the proposal of a qualitative study based on the following research questions: (i) What is the process of writing a qualitative research proposal? and (ii) What does the structure and layout of a qualitative proposal look like? The purpose of this article is to discuss the process of writing the qualitative research proposal, as well as describe the structure and layout of a qualitative research proposal. The process of writing a qualitative research proposal is discussed with regards to the most important questions that need to be answered in your research proposal with consideration of the guidelines of being practical, being persuasive, making broader links, aiming for crystal clarity and planning before you write. While the structure of the qualitative research proposal is discussed with regards to the key sections of the proposal, namely the cover page, abstract, introduction, review of the literature, research problem and research questions, research purpose and objectives, research paradigm, research design, research method, ethical considerations, dissemination plan, budget and appendices.

  19. Fuel safety research 2000

    International Nuclear Information System (INIS)

    In April 1999, the Fuel Safety Research Laboratory was newly established as a part of reorganization of the Nuclear Safety Research Center, JAERI. The new laboratory was organized by combining three pre-existing laboratories, Reactivity Accident Laboratory, Fuel Reliability Laboratory, and a part of Severe Accident Research Laboratory. The Fuel Safety Research Laboratory becomes to be in charge of all fuel safety research in JAERI. Various experimental and analytical researches are conducted in the laboratory by using the unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and hot cells in JAERI. The laboratory consists of following five research groups corresponding to each research fields; (a) Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). (b) Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). (c) Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). (d) Research group of fuel behavior analysis (FEMAXI group). (e) Research group of FP release/transport behavior from irradiated fuel (VEGA group). The research activities in year 2000 produced many important data and information. They are, for example, failure of high burnup BWR fuel rod under RIA conditions, data on the behavior of hydrided Zircaloy cladding under LOCA conditions and FP release data from VEGA experiments at very high temperature/pressure condition. This report summarizes the outline of research activities and major outcomes of the research executed in 2000 in the Fuel Safety Research Laboratory. (author)

  20. The qualitative research proposal

    Directory of Open Access Journals (Sweden)

    H Klopper

    2008-09-01

    Full Text Available Qualitative research in the health sciences has had to overcome many prejudices and a number of misunderstandings, but today qualitative research is as acceptable as quantitative research designs and is widely funded and published. Writing the proposal of a qualitative study, however, can be a challenging feat, due to the emergent nature of the qualitative research design and the description of the methodology as a process. Even today, many sub-standard proposals at post-graduate evaluation committees and application proposals to be considered for funding are still seen. This problem has led the researcher to develop a framework to guide the qualitative researcher in writing the proposal of a qualitative study based on the following research questions: (i What is the process of writing a qualitative research proposal? and (ii What does the structure and layout of a qualitative proposal look like? The purpose of this article is to discuss the process of writing the qualitative research proposal, as well as describe the structure and layout of a qualitative research proposal. The process of writing a qualitative research proposal is discussed with regards to the most important questions that need to be answered in your research proposal with consideration of the guidelines of being practical, being persuasive, making broader links, aiming for crystal clarity and planning before you write. While the structure of the qualitative research proposal is discussed with regards to the key sections of the proposal, namely the cover page, abstract, introduction, review of the literature, research problem and research questions, research purpose and objectives, research paradigm, research design, research method, ethical considerations, dissemination plan, budget and appendices.

  1. National Institute of Nursing Research

    Science.gov (United States)

    ... Life and Palliative Care Research Spotlight on Symptom Management Research Spotlight on Pain Research Training Midcareer Technical Workshop ... Life and Palliative Care Research Spotlight on Symptom Management Research Spotlight on Pain Research Training Midcareer Technical Workshop ...

  2. 'The research compass'

    DEFF Research Database (Denmark)

    Ringsted, Charlotte; Hodges, Brian; Scherpbier, Albert

    2011-01-01

    This AMEE Guide offers an introduction to research in medical education. It is intended for those who are contemplating conducting research in medical education but are new to the field. The Guide is structured around the process of transforming ideas and problems into researchable questions...... by the complexity of the field. Next is a section on how to move from an idea or problem to a research question by placing a concrete idea or problem within a conceptual, theoretical framework. The following sections are structured around an overview model of approaches to medical education research, 'The research......, choosing a research approach that is appropriate to the purpose of the study and considering the individual researcher's preferences and the contextual possibilities and constraints. The first section of the Guide addresses the rationale for research in medical education and some of the challenges posed...

  3. Responsible conduct of research

    CERN Document Server

    Shamoo, Adil E

    2015-01-01

    Since the early 2000s, the field of Responsible Conduct of Research has become widely recognized as essential to scientific education, investigation, and training. At present, research institutions with public funding are expected to have some minimal training and education in RCR for their graduate students, fellows and trainees. These institutions also are expected to have a system in place for investigating and reporting misconduct in research or violations of regulations in research with human subjects, or in their applications to federal agencies for funding. Public scrutiny of the conduct of scientific researchers remains high. Media reports of misconduct scandals, biased research, violations of human research ethics rules, and moral controversies in research occur on a weekly basis. Since the 2009 publication of the 2nd edition of Shamoo and Resnik's Responsible Conduct of Research, there has been a vast expansion in the information, knowledge, methods, and diagnosis of problems related to RCR and the ...

  4. Fuel safety research 2001

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-11-01

    The Fuel Safety Research Laboratory is in charge of research activity which covers almost research items related to fuel safety of water reactor in JAERI. Various types of experimental and analytical researches are being conducted by using some unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and the Reactor Fuel Examination Facility (RFEF) of JAERI. The research to confirm the safety of high burn-up fuel and MOX fuel under accident conditions is the most important item among them. The laboratory consists of following five research groups corresponding to each research fields; Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). Research group of fuel behavior analysis (FEMAXI group). Research group of radionuclides release and transport behavior from irradiated fuel under severe accident conditions (VEGA group). The research conducted in the year 2001 produced many important data and information. They are, for example, the fuel behavior data under BWR power oscillation conditions in the NSRR, the data on failure-bearing capability of hydrided cladding under LOCA conditions and the FP release data at very high temperature in steam which simulate the reactor core condition during severe accidents. This report summarizes the outline of research activities and major outcomes of the research executed in 2001 in the Fuel Safety Research Laboratory. (author)

  5. Qualitative Research Process

    Directory of Open Access Journals (Sweden)

    Dewan Mahboob HOSSAIN

    2011-09-01

    Full Text Available This article provides with an overview of the qualitative research methods. Over last few decades, qualitative research is getting very popular in the fields of business, sociology, psychology and others. This article, in its introduction, gives a general idea about the qualitative research. Then it discusses the main differences between qualitative and quantitative research methods. The article also discusses about the ethical issues important for qualitative research. Lastly it discusses about the several approaches and data collection methods of qualitative research.

  6. Social Work Research

    DEFF Research Database (Denmark)

    Social work research has gathered a greater transparency and clarity of identity in North American and parts of Europe. Furthermore, the rapid emergence of social work research in other European countries, China, India, Japan and elsewhere in Asia and Pacific Rim countries, and gradually in South...... understanding of the different aspects involved in the research. Volume One: Historical Trajectories, Purposes and Key Concepts Volume Two: Key Decisions about Research Strategy Volume Three: The Practice of Social Work Research Volume Four: The Contexts of Social Work Research...

  7. Research by Design - a research strategy

    DEFF Research Database (Denmark)

    Hauberg, Jørgen

    2011-01-01

    Abstract The idea of an expressive component in research is important to the architectural industry. The expressive element - the possibility of expressing the qualitative aspects of the world and adding something new to the existing through experiments and proposals - is characteristic...... for the field. All research environments, in the science tradition and in the humanities, have their characteristics. On the one hand, they live up to certain common scientific and methodological criteria - originality and transparency – and on the other hand, they have different practices, using different...... methods. Research is ‘coloured’ by traditions and professions, and research in architecture should be coloured too, taking into consideration that the practice of architects stretches from natural science and sociology to art and that the most important way in which the architect achieves new cognition...

  8. Research by design - a research strategy

    DEFF Research Database (Denmark)

    Hauberg, Jørgen

    2011-01-01

    Abstract The idea of an expressive component in research is important to the architectural industry. The expressive element - the possibility of expressing the qualitative aspects of the world and adding something new to the existing through experiments and proposals - is characteristic...... for the field. All research environments, in the science tradition and in the humanities, have their characteristics. On the one hand, they live up to certain common scientific and methodological criteria - originality and transparency - on the other hand they have different practices, using different methods....... Research is ‘coloured’ by traditions and professions, and research in architecture should be coloured too, taking in consideration that the practise of architects stretch from natural science and sociology to art, and because the most important way in which the architect achieves new cognition is through...

  9. Economics of fusion research

    International Nuclear Information System (INIS)

    This report provides the results of a study of methods of economic analysis applied to the evaluation of fusion research. The study recognizes that a hierarchy of economic analyses of research programs exists: standard benefit-cost analysis, expected value of R and D information, and expected utility analysis. It is shown that standard benefit-cost analysis, as commonly applied to research programs, is inadequate for the evaluation of a high technology research effort such as fusion research. A methodology for performing an expected value analysis is developed and demonstrated and an overview of an approach to perform an expected utility analysis of fusion research is presented. In addition, a potential benefit of fusion research, not previously identified, is discussed and rough estimates of its magnitude are presented. This benefit deals with the effect of a fusion research program on optimal fossil fuel consumption patterns. The results of this study indicate that it is both appropriate and possible to perform an expected value analysis of fusion research in order to assess the economics of a fusion research program. The results indicate further that the major area of benefits of fusion research is likely due to the impact of a fusion research program on optimal fossil fuel consumption patterns and it is recommended that this benefit be included in future assessments of fusion research economics

  10. Economics of fusion research

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1977-10-15

    This report provides the results of a study of methods of economic analysis applied to the evaluation of fusion research. The study recognizes that a hierarchy of economic analyses of research programs exists: standard benefit-cost analysis, expected value of R and D information, and expected utility analysis. It is shown that standard benefit-cost analysis, as commonly applied to research programs, is inadequate for the evaluation of a high technology research effort such as fusion research. A methodology for performing an expected value analysis is developed and demonstrated and an overview of an approach to perform an expected utility analysis of fusion research is presented. In addition, a potential benefit of fusion research, not previously identified, is discussed and rough estimates of its magnitude are presented. This benefit deals with the effect of a fusion research program on optimal fossil fuel consumption patterns. The results of this study indicate that it is both appropriate and possible to perform an expected value analysis of fusion research in order to assess the economics of a fusion research program. The results indicate further that the major area of benefits of fusion research is likely due to the impact of a fusion research program on optimal fossil fuel consumption patterns and it is recommended that this benefit be included in future assessments of fusion research economics.

  11. Nordic research in ophthalmology

    DEFF Research Database (Denmark)

    Stefánsson, Einar; Zetterström, Charlotta; Ehlers, Niels;

    2003-01-01

    Ophthalmology, eye research, cornea, catarcat, paediatric ophthalmology, glaucoma, diabetic eye disease, age-related macular degeneration, ophthalmic oncology......Ophthalmology, eye research, cornea, catarcat, paediatric ophthalmology, glaucoma, diabetic eye disease, age-related macular degeneration, ophthalmic oncology...

  12. Peat Research Seminar

    International Nuclear Information System (INIS)

    The VTT Seminar on Peat Research was held in Espoo, Finland, on April 14-15, 1993. The programme consisted of technical session on Peat in Energy Production, Peat Research Programs, Peat Production and Harvesting Technology

  13. Patient Access to Research

    Science.gov (United States)

    ... for Association Events Messaging Tools Recruiting Advocates Local Market Planning Training Webinars News & Events Advocacy News Call to Congress The Cost of Diabetes Research & Practice Home We Are Research Leaders World's Largest ...

  14. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... research volunteers. If you stutter or have a family member who stutters, you could be eligible to ... Researchers Study Stuttering? A large portion of the family clustering of stuttering is explained by genes and ...

  15. Cereal Crops Research Unit

    Data.gov (United States)

    Federal Laboratory Consortium — The mission of the Cereal Crops Research Unit is to 1) conduct basic research to identify and understand the biological processes affecting the growth, development...

  16. Fanconi Anemia Research Fund

    Science.gov (United States)

    ... Support Publications Fundraising News What is the Fanconi Anemia Research Fund? Fanconi anemia is an inherited disease that can lead to ... population. Lynn and Dave Frohnmayer started the Fanconi Anemia Research Fund, in 1989 to find effective treatments ...

  17. Basic Research Firing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Basic Research Firing Facility is an indoor ballistic test facility that has recently transitioned from a customer-based facility to a dedicated basic research...

  18. The Singapore research story

    CERN Document Server

    Teck Seng, Low; Thampuran, Raj

    2016-01-01

    Ever since Singapore became independent in 1965, its leaders have invested tremendous efforts and resources to develop its economy in order to create jobs for its people and to support national development. This book describes the challenging journey of Singapore in developing a knowledge-based economy driven by research and innovation and the roles played by research institutes, universities, research manpower and appropriate collaboration between research institutes and industry. The book traces the foundations of Singapore's research story from the time of its independence in 1965 to the present day. Through interviews with the key players and research into the records, the establishment of the key institutes and the roles of a global cast of researchers, scientists and engineers in setting up the R&D infrastructure are outlined. The impact that the concerted efforts of the last 25 years to build up a credible and world-class research capability in Singapore is discussed, as are the tremendous challeng...

  19. Shingles: Hope through Research

    Science.gov (United States)

    ... Diversity Find People About NINDS Shingles: Hope Through Research See a list of all NINDS Disorders Get ... to lessen the severity of their chickenpox. What research is being done? The mission of the National ...

  20. Lewy Body Dementia Research

    Science.gov (United States)

    ... Research Abstracts Clinical Trials Help end Lewy body dementia now! Donate Research Links Treating Psychosis in Parkinson’s ... The use of antipsychotic medications in Lewy body dementias is a known challenge. Are the medications helpful ...

  1. Greenhouse Warming Research

    DEFF Research Database (Denmark)

    Sørensen, Bent Erik

    2015-01-01

    Overview of climate research including climate models, IPCC emission scenarios and options for mitigation and adaptation.......Overview of climate research including climate models, IPCC emission scenarios and options for mitigation and adaptation....

  2. Mukilteo Research Station

    Data.gov (United States)

    Federal Laboratory Consortium — Research at the Mukilteo Research Station focuses on understanding the life cycle of marine species and the impacts of ecosystem stressors on anadromous and marine...

  3. Can research be visual?

    DEFF Research Database (Denmark)

    Martiny, Kristian Moltke

    2014-01-01

    Short film interviews with for instance researchers Birger Lindberg Møller and Andreas Roepstorff and film directors Phie Ambo, Janus Metz and Joshua Oppenheimer, about the collaboration between documentary and research: http://vimeo.com/99909839...

  4. Photochemistry research at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, C.E.; Carlson, C.E. [National Renewable Energy Laboratory, Golden, CO (United States)

    1996-09-01

    Photochemistry research team at NREL conducts research and development work in all R&D areas, basic, applied, demonstration and transfer to commercialization. Basic research includes core PCO R&D and catalysts work as well as conducting research into new photochemistry areas such as photoinduced adsorption and high temperature solar PCO. Applied research work consists of remediation of chloroethylenes in gas phase, gas phase solar photoreactor development, and application research including indoor air quality, hybrid biological/PCO processes and more. We are demonstrating the PCO treatment technology in the gas phase with SEMATECH through CRADA work and remediation of organics in aqueous phase through the Solarchem Environmental Systems. We are working with IT through a CRADA to transfer the PCO gas phase remediation technology to IT to commercialize this promising -technology. Photochemistry research conducted at NREL spans the R&D spectrum from basic research through technology demonstration with the goal of technology commercialization.

  5. Computers and Qualitative Research.

    Science.gov (United States)

    Willis, Jerry; Jost, Muktha

    1999-01-01

    Discusses the use of computers in qualitative research, including sources of information; collaboration; electronic discussion groups; Web sites; Internet search engines; electronic sources of data; data collection; communicating research results; desktop publishing; hypermedia and multimedia documents; electronic publishing; holistic and…

  6. Foundation for Sarcoidosis Research

    Science.gov (United States)

    ... Clinical Trials Fail: FSR’s New Initiative to Bridge Gap between Industry Leaders, Researchers, and Patients Guest post ... 1 2 3 … 10 Next → Foundation for Sarcoidosis Research 1820 W. Webster Ave Suite 304 Chicago, Illinois ...

  7. Understanding Medical Research

    Science.gov (United States)

    ... hear about the results of a new medical research study. Sometimes the results of one study seem ... a randomized controlled clinical trial? Where was the research done? If a new treatment was being tested, ...

  8. Educational design research

    NARCIS (Netherlands)

    McKenney, Susan; Reeves, Thomas

    2014-01-01

    McKenney, S. & Reeves, T. (2013). Educational design research. In M. Spector, M. Merrill, J. Elen & M. Bischop (Eds.) Handbook of Research on Educational Communications & Technology, pp. 131-140. London: Springer.

  9. Researching Identity and Interculturality

    DEFF Research Database (Denmark)

    Lønsmann, Dorte

    2016-01-01

    Review of: Researching Identity and Interculturality / by F. Dervin and K. Risager (eds.). Routledge 2015, 245 pp.......Review of: Researching Identity and Interculturality / by F. Dervin and K. Risager (eds.). Routledge 2015, 245 pp....

  10. Epidemiology & Genomics Research Program

    Science.gov (United States)

    The Epidemiology and Genomics Research Program, in the National Cancer Institute's Division of Cancer Control and Population Sciences, funds research in human populations to understand the determinants of cancer occurrence and outcomes.

  11. Aquatic Research Laboratory (ARL)

    Data.gov (United States)

    Federal Laboratory Consortium — Columbia River and groundwater well water sources are delivered to the Aquatic Research Laboratory (ARL), where these resources are used to conduct research on fish...

  12. Scoliosis Research Society

    Science.gov (United States)

    Back To Top Scoliosis Research Society Close Menu Member Login Become a Member Home Find a Specialist | Calendar Contact | Donate Patients and Families ... a Member Find a Specialist Calendar Contact Donate Scoliosis Research Society Dedicated to the optimal care of ...

  13. Cystic Fibrosis Research

    Science.gov (United States)

    ... please turn Javascript on. Feature: Steady Advances Against Cystic Fibrosis Cystic Fibrosis Research Past Issues / Fall 2012 Table of Contents "Remarkable strides in cystic fibrosis research over the past two decades have culminated ...

  14. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... affects a person’s quality of life. Dennis Drayna, Ph.D., an intramural researcher at the National Institute ... people can actually do things to mitigate the effects of the disorder. How Do Researchers Study Stuttering? ...

  15. Chinese Ecosystem Research Network

    Institute of Scientific and Technical Information of China (English)

    Huang Tieqing; Liu Jian; Chen Panqin; Fu Bojie

    2002-01-01

    The article analyzes the development of the Chinese Ecosystem Research Network, and its mission, mandate, and management mechanisms, with examples of research, demonstration and consultation for policy-setting.

  16. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Repayment More » Search the NIH Guide Quick Links RePORT eRA Commons NIH Common ... & Training Medical Research Initiatives Science Highlights Science Education Research in ...

  17. Contemporary Danish landscape research

    DEFF Research Database (Denmark)

    Vejre, Henrik; Brandt, Jesper

    2004-01-01

    Danish landscape research blossomed during the 1990’ies thanks to several transdisciplinary research programmes involving several institutions. The main themes of the programmes encompassed Landscape change, landscape and biological diversity, nature and landscape management, use and monitoring...

  18. Research Reports: Marijuana

    Science.gov (United States)

    ... 625KB) Online Only Marijuana and Cannabinoids: A Neuroscience Research Summit March 22-23, 2016 Meeting Summary Featured ... Parents Need to Know Marijuana: Facts for Teens ​Research Reports This series of reports simplifies the science ...

  19. CNPC International Research Center

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ CNPC International Research Center (CNPCIRC), jointly managed by CNODC and RIPED of China National Petroleum Corporation (CNPC), was established in 1999 for providing technical research support to all the overseas oil and gas projects of CNPC.

  20. NASA propeller noise research

    Science.gov (United States)

    Greene, G. C.

    1980-01-01

    The research in propeller noise prediction, noise/performance optimization, and interior reduction is described. Selected results are presented to illustrate the status of the technology and the direction of future research.

  1. Fashion design research

    OpenAIRE

    Mbonu, Ezinma

    2014-01-01

    Every fashion collection begins with research. But how do you start? How much should you do? How do you use that research? This book is designed to answer these questions and demystify the process for students. Illustrated throughout with inspirational photographs and images of good practice within student sketchbooks, the book begins with the basics of primary and secondary research sources and shows students how and where to gather information. Chapters on market, fabric and colour research...

  2. "Education-based Research"

    DEFF Research Database (Denmark)

    Degn Johansson, Troels

    This paper lays out a concept of education-based research-the production of research knowledge within the framework of tertiary design education-as an integration of problem-based learning and research-based education. This leads to a critique of reflective practice as the primary way to facilitate...... learning at this level, a discussion of the nature of design problems in the instrumentalist tradition, and some suggestions as to how design studies curricula may facilitate education-based research....

  3. Science Education Research vs. Physics Education Research: A Structural Comparison

    OpenAIRE

    Akarsu, Bayram

    2011-01-01

    The main goal of this article is to introduce physics education research (PER) to researchers in other fields. Topics include discussion of differences between science education research (SER) and physics education research (PER), physics educators, research design and methodology in physics education research and current research traditions and trends (e.g. current research ideas) within PER.

  4. Action and Interactiv research

    DEFF Research Database (Denmark)

    Nielsen, Kurt Aagaard; Svensson, Lennart

    The text is written as a first version of editors introduction to a book about action research/interactive research in Nordic countries. You can read abouttrends and contradictions in the history of action research.The authors question the trends and demands a more explicit critical approach...

  5. Nuclear safety research

    International Nuclear Information System (INIS)

    The NNSA checked and coordinated in 1999 the research project of the Surveillance Technology on Nuclear Installations under the National 9th-Five-Year Program to promote the organizations that undertake the research work on schedule and lay a foundation of obtaining achievements and effectiveness for the 9th-five-year plan on nuclear safety research

  6. Research at NPS, poster

    OpenAIRE

    Naval Postgraduate School (U.S.)

    2010-01-01

    A primary goal of the Naval Postgraduate School research program is to provide economical research and unique laboratory facilities that allow students and faculty to support Navy/DoD needs. We offer independent assessment of proposed solutions to military issues, pre-deployment evaluation of new technologies, and combined student– faculty expertise for research and development programs.

  7. Our Celebration of Research

    OpenAIRE

    Joon-Wah Mak

    2008-01-01

    The International Medical University (IMU)has encouraged and facilitated research activitiessince 2001. Research activities by undergraduates,postgraduates, and faculty members have increasedsubstantially since then. The governance aspects ofresearch activities are closely monitored by theInstitutional Review Board which is the IMU-JointCommittee on Research and Ethics.

  8. Researching entrepreneurship with autoethnography

    DEFF Research Database (Denmark)

    Gottlieb, Frederik

    2015-01-01

    making process, thus directly affecting the context. The paper concludes that deep involvement when researching entrepreneurial contexts is important to explore new themes, however in these processes the researchers involvement will inevitably affect the the context and those being researched as well....

  9. Mapping MSW Research Training

    Science.gov (United States)

    Freymond, Nancy; Morgenshtern, Marina; Duffie, Mark; Hong, Liu; Bugeja-Freitas, Shirley; Eulenberg, Jesse

    2014-01-01

    The surge of interest in evidence-based interventions necessitates MSW graduates who will pursue research activities in the workplace. However, evidence suggests that social workers tend not to use their research skills after graduation. This study examined three constructs that inform students' relationships to research: (a) confidence in…

  10. Evidence and Policy Research

    Science.gov (United States)

    Schuller, Tom; Jochems, Wim; Moos, Lejf; van Zanten, Agnes

    2006-01-01

    The EERJ roundtable took as its point of departure the experience of the Organisation for Economic Cooperation and Development's (OECD) Centre for Educational Research and Innovation (CERI) in carrying out policy research. CERI has conducted four reviews of national educational research and development (in New Zealand, England, Mexico and…

  11. Basic Research Objectives Reaffirmed

    Institute of Scientific and Technical Information of China (English)

    Guo Haiyan; Zhao Baohua

    2002-01-01

    @@ As a national institution for scientific research and a component of the national innovation system, CAS should and must make key contributions to the great national rejuvenation of the country. Keeping this in mind, CAS has developed four developmental targets for its basic research. This was revealed at a CAS conference on basic research held June 11-12 in Beijing.

  12. Educational design research

    NARCIS (Netherlands)

    McKenney, S.E.; Reeves, Thomas C.; Spector, J. Michael; Merrill, M. David; Elen, Jan; Bishop, M.J.

    2014-01-01

    Educational design research is a genre of research in which the iterative development of solutions to practical and complex educational problems provides the setting for scientific inquiry. The solutions can be educational products, processes, programs, or policies. Educational design research not o

  13. Music Researchers' Musical Engagement

    Science.gov (United States)

    Wollner, Clemens; Ginsborg, Jane; Williamon, Aaron

    2011-01-01

    There is an increasing awareness of the importance of reflexivity across various disciplines, which encourages researchers to scrutinize their research perspectives. In order to contextualize and reflect upon research in music, this study explores the musical background, current level of musical engagement and the listening habits of music…

  14. Research in International Education

    Science.gov (United States)

    Dolby, Nadine; Rahman, Aliya

    2008-01-01

    Until recently, international education has existed at the margins of educational research. However, in the current context of globalization, international education has moved closer to the center of educational research throughout the world. In this article, the authors identify, describe, and analyze six distinct research approaches to…

  15. Researching online supervision

    DEFF Research Database (Denmark)

    Bengtsen, Søren S. E.; Mathiasen, Helle

    2014-01-01

    us to research the digital tools on their own premises as autonomous things in themselves, possessing an ontological creativity of their own. In order for qualitative research to match the ontological nature of digital tools we conclude the article by formulating three criteria of a ‘torn......’ methodology that makes room for new approaches to researching online supervision at the university....

  16. Researching the future

    OpenAIRE

    Browning, Helen

    2002-01-01

    The author, a recent Chair of the Soil Association and an organic farmer, examines the relationship between the research community and farmers, and argues for publicly funded, radical 'pioneering research' which will increase the sustainability of organic farming and deliver greater benefits. This will require genuine collaboration between researchers, farmers and the public.

  17. Research Methods in Education

    Science.gov (United States)

    Check, Joseph; Schutt, Russell K.

    2011-01-01

    "Research Methods in Education" introduces research methods as an integrated set of techniques for investigating questions about the educational world. This lively, innovative text helps students connect technique and substance, appreciate the value of both qualitative and quantitative methodologies, and make ethical research decisions.…

  18. Research Interview Discourse

    NARCIS (Netherlands)

    Ensink, Eustatius

    2015-01-01

    The purpose of research interviews is to obtain information from different respondents in order to answer a research question. The two main types of research interviews are standardized survey interviews and open interviews. The information obtained should meet scientific requirements. These require

  19. Research into Practice: Vocabulary

    Science.gov (United States)

    Nation, I. S. P.

    2011-01-01

    This article is a personal view of the application of research on vocabulary to teaching and how there are three different types or categories of relationship between that research and the teaching to which it is applied: first, where the research is not applied or not applied well, second, where it is reasonably well applied, and third, where it…

  20. Research at WNRE

    International Nuclear Information System (INIS)

    A broad overview of the structure and research of Whiteshell Nuclear Research Establishment (WNRE) is presented. The research programs are divided amongst four divisions and a new business project: Waste Management Division, Applied Science Division, Chemistry and Materials Science Division, Mini-Reactor Business, and the Health and Safety Division. All divisions are briefly described. Emphasis is placed upon the Health and Safety division

  1. Design-based research

    NARCIS (Netherlands)

    Reeves, Thomas; McKenney, Susan

    2016-01-01

    Educational design research is a genre of research in which the iterative development of solutions to practical and complex educational problems provides the setting for scientific inquiry. The solutions can be educational products, processes, programs or policies. Educational design research not on

  2. Rich Design Research Space

    Directory of Open Access Journals (Sweden)

    Birger Sevaldson

    2008-10-01

    Full Text Available This paper introduces and discusses a Rich Research Space as an inclusive methodological framework and scaffold for research-by-design. The Rich Research Space especially addresses the issue of richness in design processes and design-led research. There is a general trend towards increased complexity in design processes, caused on one hand by the increasing depth and width in the use of design media and methods, and on the other hand by the increasing complexity and interdependency of society due to globalisation. These issues confront the designer-researcher with new challenges. This paper formulates a research strategy for research-by-design in fields that have a high degree of richness in the use of media, the amount of information, and the methods involved. The Rich Research Space concept proposed takes into account the physical, social, and cultural spaces, and the virtual and visual media spaces in which the research-by-design takes place. The concept takes the form of a specific integral approach to design, and a holistic theoretical mindset. It embraces many types of investigation, from analytical to intuitive. The Rich Research Space provides a flexible framework within which the complexity of research-by-design can be interrelated, discussed, and reflected upon. Potentially, it can create a more involved role for the designer-researcher, a role that allows contributions towards the resolution of ever more pressing issues in our society. This approach is currently one of a limited number of possible frameworks that the design professions can utilize in order to make a difference in a world of at times overwhelming complexity. The concept of the Rich Research Space is discussed with reference to an art installation called Barely.Keywords: Research by design, collaborative design, complexity, creativity, research methods.

  3. Edge Transport Modeling using the 3D EMC3-Eirene code on Tokamaks and Stellarators

    Science.gov (United States)

    Lore, J. D.; Ahn, J. W.; Briesemeister, A.; Ferraro, N.; Labombard, B.; McLean, A.; Reinke, M.; Shafer, M.; Terry, J.

    2015-11-01

    The fluid plasma edge transport code EMC3-Eirene has been applied to aid data interpretation and understanding the results of experiments with 3D effects on several tokamaks. These include applied and intrinsic 3D magnetic fields, 3D plasma facing components, and toroidally and poloidally localized heat and particle sources. On Alcator C-Mod, a series of experiments explored the impact of toroidally and poloidally localized impurity gas injection on core confinement and asymmetries in the divertor fluxes, with the differences between the asymmetry in L-mode and H-mode qualitatively reproduced in the simulations due to changes in the impurity ionization in the private flux region. Modeling of NSTX experiments on the effect of 3D fields on detachment matched the trend of a higher density at which the detachment occurs when 3D fields are applied. On DIII-D, different magnetic field models were used in the simulation and compared against the 2D Thomson scattering diagnostic. In simulating each device different aspects of the code model are tested pointing to areas where the model must be further developed. The application to stellarator experiments will also be discussed. Work supported by U.S. DOE: DE-AC05-00OR22725, DE AC02-09CH11466, DE-FC02-99ER54512, and DE-FC02-04ER54698.

  4. Radiation Rates for Low Z Impurities in Edge Plasmas

    CERN Document Server

    Clark, R; Post, D

    1995-01-01

    The role of impurity radiation in the reduction of heat loads on divertor plates in present experiments such as DIII-D, JET, JT-60, ASDEX, and Alcator C-Mod, and in planned experiments such as ITER and TPX places a new degree of importance on the accuracy of impurity radiation emission rates for electron temperatures below 250 eV for ITER and below 150 eV for present experiments. We have calculated the radiated power loss using a collisional radiative model for Be, B, C, Ne and Ar using a multiple configuration interaction model which includes density dependent effects, as well as a very detailed treatment of the energy levels and meta-stable levels. The "collisional radiative" effects are very important for Be at temperatures below 10 eV. The same effects are present for higher Z impurities, but not as strongly. For some of the lower Z elements, the new rates are about a factor of two lower than those from a widely used, simpler average-ion package (ADPAK) developed for high Z ions and for higher temperature...

  5. Studies of ELM heat load, SOL flow and carbon erosion from existing tokamak experiments, and projections for ITER

    International Nuclear Information System (INIS)

    Three important physics issues for the ITER divertor design and operation are summarized based on the experimental and numerical work from multi-machine database (JET, JT-60U, ASDEX Upgrade, DIII-D, Alcator C-Mod and TEXTOR). (i) The energy load associated with Type-I ELMs is of great concern for the lifetime of the ITER divertor target. In order t o understand the physics base of the scaling models[1], the ELM heat and particle transport from the edge pedestal to the divertor is investigated. Convective transport during ELMs plays an important role in heat transport to the divertor. (ii) Determination of the SOL flow pattern and the driving mechanism has progressed experimentally and numerically. Influences of the drift effects on the SOL and divertor plasma transport were discussed. (iii) Carbon erosion and redeposition are of great importance in particular for tritium retention via codeposition. Characteristics of chemical yield at two different deposited carbon surfaces, i.e. erosion- and redeposition-dominated areas, have been studied. Progress in the understanding of the chemical erosion is reviewed. (author)

  6. Spatially Resolved Spectra from a new X-ray Imaging Crystal Spectrometer for Measurements of Ion and Electron Temperature Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Stratton, B; Roquemore, A; Mastrovito, D; Lee, S; Bak, J; Moon, M; Nam, U; Smith, G; Rice, J; Beiersdorfer, P; Fraenkel, B

    2004-08-10

    A new type of high-resolution X-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument is particularly valuable for diagnosing plasmas with purely Ohmic heating and rf heating, since it does not require the injection of a neutral beam - although it can also be used for the diagnosis of neutral-beam heated plasmas. The spectrometer consists of a spherically bent quartz crystal and a two-dimensional position-sensitive detector. It records spectra of helium-like argon (or krypton) from multiple sightlines through the plasma and projects a de-magnified image of a large plasma cross-section onto the detector. The spatial resolution in the plasma is solely determined by the height of the crystal, its radius of curvature, and the Bragg angle. This new X-ray imaging crystal spectrometer may also be of interest for the diagnosis of ion temperature profiles in future large tokamaks, such as KSTAR and ITER, where the application of the presently used charge-exchange spectroscopy will be difficult, if the neutral beams do not penetrate to the plasma center. The paper presents the results from proof-of-principle experiments performed with a prototype instrument at Alcator C-Mod.

  7. Development of the gas puff charge exchange recombination spectroscopy (GP-CXRS) technique for ion measurements in the plasma edge

    International Nuclear Information System (INIS)

    A novel charge-exchange recombination spectroscopy (CXRS) diagnostic method is presented, which uses a simple thermal gas puff for its donor neutral source, instead of the typical high-energy neutral beam. This diagnostic, named gas puff CXRS (GP-CXRS), is used to measure ion density, velocity, and temperature in the tokamak edge/pedestal region with excellent signal-background ratios, and has a number of advantages to conventional beam-based CXRS systems. Here we develop the physics basis for GP-CXRS, including the neutral transport, the charge-exchange process at low energies, and effects of energy-dependent rate coefficients on the measurements. The GP-CXRS hardware setup is described on two separate tokamaks, Alcator C-Mod and ASDEX Upgrade. Measured spectra and profiles are also presented. Profile comparisons of GP-CXRS and a beam based CXRS system show good agreement. Emphasis is given throughout to describing guiding principles for users interested in applying the GP-CXRS diagnostic technique

  8. Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks

    DEFF Research Database (Denmark)

    Wright, J.C.; Bonoli, P.T.; Brambilla, M.;

    2004-01-01

    Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k(perpendi......Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k......(perpendicular to)rho(i)similar to1 which leads to a scaling of the maximum poloidal mode number, M-max, proportional to 1/rho(*) (rho(*)equivalent torho(i)/L). The computational resources needed scale with the number of radial (N-r), poloidal (N-theta), and toroidal (N-phi) elements as N-r * N-phi * N-theta(3...... time are capable of achieving the resolution and speed necessary to address mode conversion phenomena in full two-dimensional (2-D) toroidal geometry. These codes have been used in conjunction with theory and experimental data from the Alcator C-Mod [I. H. Hutchinson , Phys. Plasmas 1, 1511 (1994...

  9. Is X-ray emissivity constant on magnetic flux surfaces?

    International Nuclear Information System (INIS)

    Knowledge of the elongations and shifts of internal magnetic flux surfaces can be used to determine the q profile in elongated tokamak plasmas. X-ray tomography is thought to be a reasonable technique for independently measuring internal flux surface shapes, because it is widely believed that X-ray emissivity should be constant on a magnetic flux surface. In the Alcator C-Mod tokamak, the X-ray tomography diagnostic system consists of four arrays of 38 chords each. A comparison of reconstructed X-ray contours with magnetic flux surfaces shows a small but consistent discrepancy in the radial profile of elongation. Numerous computational tests have been performed to verify these findings, including tests of the sensitivity to calibration and viewing geometry errors, the accuracy of the tomography reconstruction algorithms, and other subtler effects. We conclude that the discrepancy between the X-ray contours and the magnetic flux surfaces is real, leading to the conclusion that X-ray emissivity is not exactly constant on a flux surface. (orig.)

  10. Development of the gas puff charge exchange recombination spectroscopy (GP-CXRS) technique for ion measurements in the plasma edge

    Energy Technology Data Exchange (ETDEWEB)

    Churchill, R. M.; Theiler, C.; Lipschultz, B. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Dux, R.; Pütterich, T.; Viezzer, E. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Collaboration: Alcator C-Mod Team; ASDEX Upgrade Team

    2013-09-15

    A novel charge-exchange recombination spectroscopy (CXRS) diagnostic method is presented, which uses a simple thermal gas puff for its donor neutral source, instead of the typical high-energy neutral beam. This diagnostic, named gas puff CXRS (GP-CXRS), is used to measure ion density, velocity, and temperature in the tokamak edge/pedestal region with excellent signal-background ratios, and has a number of advantages to conventional beam-based CXRS systems. Here we develop the physics basis for GP-CXRS, including the neutral transport, the charge-exchange process at low energies, and effects of energy-dependent rate coefficients on the measurements. The GP-CXRS hardware setup is described on two separate tokamaks, Alcator C-Mod and ASDEX Upgrade. Measured spectra and profiles are also presented. Profile comparisons of GP-CXRS and a beam based CXRS system show good agreement. Emphasis is given throughout to describing guiding principles for users interested in applying the GP-CXRS diagnostic technique.

  11. Edge Plasma Mode as the Signature of the EDA H-Regime

    Science.gov (United States)

    Basu, B.; Coppi, B.; Zhou, T.

    2012-03-01

    A deep Er-well observed in the EDA H-Regime produced by the Alcator C-Mod machine is considered as inducing a sharp localization of the Quasi-Coherent Mode proposed as the signature of this regime. This has a phase velocity in the ion diamagnetic velocity direction, in the plasma reference frame [1], and is a ``viscous-ballooning-mode'' driven by the combined effects of the plasma pressure gradient and the magnetic field curvature that would be stable due to FLR effects in the absence of a finite viscosity î. The frequency is near φdi≡kφvdi where vdi≡-[c/(e nBθ)]d pi/dr and kφ= n^0/R. The relevant model dispersion relation [2] obtained for a plane geometry in which the magnetic field curvature is simulated by an effective gravity is (φ+iγμ)(φ-φdi)=-2̂IC+ k^2vA^2/[1+i k^2Dm/(φ-φ*e)], where γμî, γIC is the interchange growth rate, Dm≡c^2η/(4π), η is the longitudinal resistivity and φ*e≡[ckφTe/(enBθ)](dn/dr)(1+1.71dTe/dne).[4pt] [1] I. Cziegler (2010).[0pt] [2] B. Coppi, et al., Ann. Phys. 121,1 (1979)

  12. Structure and Characteristics of the Quasi-Coherent Mode in EDA H-mode Plasmas

    Science.gov (United States)

    Cziegler, I.; Terry, J. L.; Lin, L.; Snipes, J. A.; Porkolab, M.

    2006-10-01

    The quasi-coherent mode (QCM), an edge fluctuation present in Enhanced Dα (EDA) H-mode confinement in Alcator C-Mod, is thought to have a decisive role in enhancing particle transport through the edge pedestal of these plasmas. We present detailed data of the mode structure both in real and spectral space, the propagation speed and direction in various regimes, and additional information on the resistive ballooning character of the mode (e.g. mode propagation with k.B 0 in the counter-current direction). We see a second harmonic at twice the frequency and poloidal wavenumber of the fundamental of the mode (kfundcirc at z = 0 varies between 1-2 cm-1); a radial phase variation over the ˜1 cm region across the pedestal where the mode is present; and a ballooning-like poloidal variation in amplitude. These observations will be used to examine the strengths and weaknesses of different models of the QC fluctuation, and should be of use in understanding its mechanism.

  13. Mitigation of radio frequency sheaths through magnetic field-aligned ICRF antenna design

    International Nuclear Information System (INIS)

    Highlights: ► First comparison of magnetic field-aligned ICRF antenna with horizontal ICRF antenna using 3-D finite element cold plasma model. ► Simulations suggest a reduction of the integrated parallel electric field for all toroidal phasings for a field-aligned antenna compared with a conventional antenna. ► The largest reduction in the RF potential occurs for monopole phasing, which has the largest RF potential contribution for conventional ICRF antennas. - Abstract: One of the primary challenges of auxiliary heating of tokamaks in the ion cyclotron range of frequencies (ICRF) is the reduction of impurities associated with ICRF operation. On Alcator C-Mod, a new magnetic field-aligned antenna was optimized for magnetic flux coupling, power handling, and minimized integrated parallel electric field (E∥). Initial simulations performed using both slab and cylindrical geometry suggested nearly complete cancellation of E∥ in front of the antenna structure for certain toroidal phasings. Using toroidal models, the cancellation of E∥ is more modest, suggesting 3-D geometrical effects are important. Using finite element method simulations with a 3-D toroidal cold plasma model, multiple antenna phases were analyzed: [0, π, 0, π], [0, 0, π, π], [0, π, π, 0], [0, 0, 0, 0], [0, π/6, 0, π/6], and [0, π/2, π, 3π/2]. In each case, the field-aligned antenna had reduced integrated E∥ relative to the existing non-aligned antenna geometry, with the greatest reduction for monopole [0, 0, 0, 0] phasing.

  14. Environmental education policy research

    DEFF Research Database (Denmark)

    Læssøe, Jeppe; Feinstein, Noah Weeth; Blum, Nicole

    2013-01-01

    in the areas of Environmental Education (EE), Education for Sustainable Development and Climate Change Education. It especially makes a case for two kinds of research on EE policy: (1) a multi-sited approach to empirical documentation and theory development which explores the relationships between......This essay examines the relationship between research and policy and, more specifically, how researchers might relate to policy work. Given the current international policy focus on climate change, green growth and sustainability in general, it argues for strengthening and widening policy research...... international policy agreements and local practice, and (2) an interactive policy-engaged approach to research....

  15. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    Analysing processes of social learning this work addresses how action research can further new research orientations towards sustainability. Empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating...... with a greater say in the future of urban sustainability research, the work shows how action research can make important methodological contributions to processes of social learning between citizens and scientists by enabling free spaces in peoples everyday life and within academia, where aspects...... of unsustainability can be addressed and new imaginations of more sustainable futures emerge....

  16. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    How can action research further new research orientations towards sustainability? This book, empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating on urban sustainability, answers this question...... to provide local citizens with a greater say in the future of urban sustainability research, this book shows how action research can make important methodological contributions to processes of social learning between citizens and scientists by enabling free spaces in peoples everyday life and within academia......, where aspects of un-sustainability can be addressed and new imaginations of more sustainable futures emerge...

  17. Teaching and researching

    CERN Document Server

    Grabe, William

    2013-01-01

    Teaching and Researching Reading was first written to help language professionals understand the complex nature of reading. Now in a thoroughly updated and improved second edition, the book expands connections from research on reading to instructional practices and teacher-initiated action research. Offering an updated overview of reading theory, it summarises key ideas and issues in first and second language contexts.In addition to providing insightful research analyses, Grabe and Stoller offer practical advice for practitioners and researchers, including evidence-based teaching ideas and a m

  18. Action research: Scandinavian Experiences

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard

    2004-01-01

    The article focus on paradigms, methods and ethics of action research in the Scandinavian countries. The special features of the action research paradigm is identified. A historical overview follows of some main action research projects in Norway, Sweden and Denmark. The tendency towards upsclae...... action research projects from organisational or small community projects yo large-scale, regional based network apporaches are also outlined and discussed. Finally, a synthesised approach of the classical, socio-technical action research approach and the large-scale network and holistic approaches is...

  19. Researching the Classroom

    Institute of Scientific and Technical Information of China (English)

    陆军

    2014-01-01

    This paper explains how any teacher can do their own classroom research as a part of their normal teaching. In order to research the classroom,it reviews some teacher’s questions in the classroom.After introducing two ways of researching :research by thinking and research by experimenting ,the paper analyses the reasons and shows some methods to solve the problems. This will determine the shape of what is done in the classroom exactly.It’s helpful for the teachers to have lessons every day.

  20. Directions for further research

    DEFF Research Database (Denmark)

    Minsaas, Atle; Psaraftis, Harilaos N.

    2015-01-01

    chapter of this book we discuss directions for further research in this area. We do so by taking stock of (1) related recommendations of project SuperGreen, and (2) related activities mainly in European research. Links between research and policy-making as two activities that should go hand in hand......Green transportation logistics is an area that combines the following: (a) it is relatively new in terms of research carried out thus far, (b) it has become increasingly important for both industry and society, and (c) it is rich in topics for further research, both basic and applied. In this final...

  1. Finnish bioenergy research programme

    Energy Technology Data Exchange (ETDEWEB)

    Asplund, D. [VTT Energy, Jyvaeskylae (Finland)

    1996-12-31

    Finland is a leading country in the use of biofuels and has excellent opportunities to increase the use of biofuels by up to 25-30 %. The Finnish Government has set an objective for the promotion of bioenergy. The aim is to increase the use of bioenergy by about 25 % from the present level by 2005, and the increment corresponds to 1.5 million tonnes of oil equivalent (toe) per year. The R and D work has been considered as an important factor to achieve this ambitious goal. Energy research was organised into a series of research programmes in 1988 in accordance with the proposal of Finnish Energy Research Committee. The object of the research programmes is to enhance research activities and to bundle individual projects together into larger research packages. The common target of the Finnish energy research programmes is to proceed from basic and applied research to product development and pilot operation, and after that to the first commercial applications, e.g. demonstrations. As the organisation of energy research to programmes has led to good results, the Finnish Ministry of Trade and Industry decided to go on with this practice by launching new six-year programmes in 1993-1998. One of these programmes is the Bioenergy Research Programme and the co-ordination of this programme is carried out by VTT Energy. Besides VTT Energy the Finnish Forest Research Institute, Work Efficiency Institute, Metsaeteho and University of Joensuu are participating in the programme 7 refs.

  2. Dynamic Research Sketching

    DEFF Research Database (Denmark)

    Markussen, Thomas; Bang, Anne Louise; Knutz, Eva;

    2012-01-01

    In this paper we offer a new explanatory tool, called ‘dynamic research sketching’ useful for mapping and understanding how research through design can be a vehicle for theory construction. ‘Research through design’ is often used as an all-inclusive umbrella term for research practices that recog......In this paper we offer a new explanatory tool, called ‘dynamic research sketching’ useful for mapping and understanding how research through design can be a vehicle for theory construction. ‘Research through design’ is often used as an all-inclusive umbrella term for research practices...... that recognize the process of designing and making an artifact as a legitimate method of inquiry. However, even though this type of research is thus grounded in design practice there are many different ways in which the process of designing and making an artifact can be used as a method of inquiry in order...... to explore a research question. Occasionally, the lack of a systematic methodology for research through design being able to make clarifications and distinctions between various methods has been pointed out. Yet, only few attempts have been made to compensate for this lack. In this paper, the aim is to make...

  3. Training research through EFL

    Directory of Open Access Journals (Sweden)

    Mardanshina Rimma M.

    2016-01-01

    Full Text Available In a globalized research market, developing students’ research skills by means of a foreign language is of particular importance. Students’ research work within the framework of the syllabus and extracurricular activities constitute the system of scientific work of students in a higher education institution. The potential of a foreign language in shaping the academic and research competence of students of Economics is revealed in the content and process aspects. Linguistics and economics as fields of scientific knowledge are reflected in the content aspect. Regarding the mode of training research, the emphasis is on reading strategies and activities aimed at fluent comprehension and handling professional and scientific information. Students’ scientific conference survey proves the potential of EFL in research activities and sheds the light on the new ways to develop research competence.

  4. Materials research at CMAM

    Science.gov (United States)

    Zucchiatti, Alessandro

    2013-07-01

    The Centro de Micro Analisis de Materiales (CMAM) is a research centre of the Universidad Autónoma de Madrid dedicated to the modification and analysis of materials using ion beam techniques. The infrastructure, based on a HVEE 5MV tandem accelerator, provided with a coaxial Cockcroft Walton charging system, is fully open to research groups of the UAM, to other public research institutions and to private enterprises. The CMAM research covers a few important lines such as advanced materials, surface science, biomedical materials, cultural heritage, materials for energy production. The Centre gives as well support to university teaching and technical training. A detail description of the research infrastructures and their use statistics will be given. Some of the main research results will be presented to show the progress of research in the Centre in the past few years and to motivate the strategic plans for the forthcoming.

  5. Researching with undergraduate students

    DEFF Research Database (Denmark)

    Wulf-Andersen, Trine Østergaard; Mogensen, Kevin; Hjort-Madsen, Peder

    2013-01-01

    this particular intertwined research and education arrangement. We show that the connection to the research project assisted students to orientate, learn, and contribute in relation to empirical and theoretical aspects of research and supported the development of broad perspectives and deep analysis....... as "research learners" rather than merely curriculum learners proves productive for both research and teaching. We describe the specific university learning context and the particular organization of undergraduate students' supervision and assistantships. The case builds on and further enhances a well......-established and proven university model of participant-directed, problem-oriented project work. We explore students' and researchers' experiences of being part of the collaboration, focusing on learning potentials and dilemmas associated with the multiple roles of researcher and student that characterized...

  6. Materials research at CMAM

    International Nuclear Information System (INIS)

    The Centro de Micro Analisis de Materiales (CMAM) is a research centre of the Universidad Autónoma de Madrid dedicated to the modification and analysis of materials using ion beam techniques. The infrastructure, based on a HVEE 5MV tandem accelerator, provided with a coaxial Cockcroft Walton charging system, is fully open to research groups of the UAM, to other public research institutions and to private enterprises. The CMAM research covers a few important lines such as advanced materials, surface science, biomedical materials, cultural heritage, materials for energy production. The Centre gives as well support to university teaching and technical training. A detail description of the research infrastructures and their use statistics will be given. Some of the main research results will be presented to show the progress of research in the Centre in the past few years and to motivate the strategic plans for the forthcoming

  7. Sustainable Consumption: Research Challenges

    DEFF Research Database (Denmark)

    Reisch, Lucia A.; Cohen, Maurie J.; Thøgersen, John;

    The Board of the Swedish Foundation for Strategic Environmental Research (Mistra) decided in October 2015 that a proposal for a funding application call in the research area of “sustainable consumption” should be drawn up. According to the statutes of Mistra, research funded by the foundation...... policy) processes that are underway in Sweden and the rest of the European Union (EU) to tackle these challenges; ► to provide an overview of where the international research frontline is located and the status of Swedish research gaps in the area from an international perspective; ► to propose in detail...... “shall promote the development of strong research environments of the highest international class with importance for Sweden’s future competitiveness. The research shall be of importance for finding solutions to important environmental problems and for a sustainable development of society. Opportunities...

  8. eParticipation Research

    DEFF Research Database (Denmark)

    Medaglia, Rony

    2012-01-01

    Research on the use of information technology to support democratic decision-making (eParticipation) is experiencing ongoing growth, stimulated by an increasing attention from both practitioner and research communities. This study provides the first longitudinal analysis of the development of the e......Participation field based on a shared framework, capturing the directions that the research field of eParticipation is taking in recent developments. Drawing on a literature search covering the period from April 2006 to March 2011, this study identifies, analyzes, and classifies 122 research articles within...... also suggests new analytical categories of research. Drawing on the analysis, inputs for a research agenda are suggested. These include the need to move beyond a technological perspective, encouraging the ongoing shift of research focus from government to citizens and other stakeholders, and the need...

  9. THE ACTION RESEARCH METHOD

    Directory of Open Access Journals (Sweden)

    Petre GEORGIEVSKI

    1999-05-01

    Full Text Available The effort in this work to elaborate an action research method as a central research problem considering the recent contemporary sociological and educa­tional literature. The author begins with the statement that the method is a complex notion, composed of three main components: approach to the research problem, data gathering procedures and data analysis procedures. This point of view is further applied and elaborated in the author's text, emphasizing the action research characteristics: interruption with the positive tradition in social research and the divided of the objective and subjective, application of the qualitative data. The sub­stantial difference between the action research in regard with the other kinds of research, is not only in getting to new knowledge's, but also in problem solving or a change in the situation in a concrete social context.

  10. Ecological Research Division, Marine Research Program

    Energy Technology Data Exchange (ETDEWEB)

    1980-05-01

    This report presents program summaries of the various projects sponsored during 1979 by the Marine Research Program of the Ecological Research Division. Program areas include the effects of petroleum hydrocarbons on the marine environment; a study of the baseline ecology of a proposed OTEC site near Puerto Rico; the environmental impact of offshore geothermal energy development; the movement of radionuclides through the marine environment; the environmental aspects of power plant cooling systems; and studies of the physical and biological oceangraphy of the continental shelves bordering the United States.

  11. Ecological Research Division, Marine Research Program

    International Nuclear Information System (INIS)

    This report presents program summaries of the various projects sponsored during 1979 by the Marine Research Program of the Ecological Research Division. Program areas include the effects of petroleum hydrocarbons on the marine environment; a study of the baseline ecology of a proposed OTEC site near Puerto Rico; the environmental impact of offshore geothermal energy development; the movement of radionuclides through the marine environment; the environmental aspects of power plant cooling systems; and studies of the physical and biological oceangraphy of the continental shelves bordering the United States

  12. Science Education Research vs. Physics Education Research: A Structural Comparison

    Science.gov (United States)

    Akarsu, Bayram

    2010-01-01

    The main goal of this article is to introduce physics education research (PER) to researchers in other fields. Topics include discussion of differences between science education research (SER) and physics education research (PER), physics educators, research design and methodology in physics education research and current research traditions and…

  13. Leadership in research

    International Nuclear Information System (INIS)

    Research to underpin clinical activity in radiographic practice is rapidly becoming a requirement and not an option. Whilst it is recognised that the ability to undertake research demands suitable training in research itself, arguments have been given which indicate that without adequate leadership abilities the research activity may not develop or flourish. In the context of radiography this review paper initially argues a need for research leadership in the clinical (and academic) environment. The debate then moves to consider one method of leadership (transformational) that might be suitable. Transformational leadership is rapidly gaining popularity within the National Health Service. Finally, the debate focuses on the professional ('taught') doctorate as a means of acquiring both research and leadership training and education within one university course

  14. Architectural Practice as Research

    DEFF Research Database (Denmark)

    Hougaard, Anna Katrine

    2015-01-01

    , qualitative and quantitative, scientific and artistic methods pollinate each other, and an attempt to set up a span for ‘research by design’ to unfold in, rather than a rigid definition. In mutual exploitation architectural writing, drawing and potentially the construction of objects with properties embodied...... in them, is the very research. This approach is framed by Deleuze’s reading of Bergson’s intuitive method and Peirce’s concept abduction, both methods which concern creative processes, material production and organisation, and the breakthrough of novelty.......The paper discusses a kind of research which lies between ‘research by design’ and ‘artistic research’. The term ‘research by design’ is reconstructed to include artistic ways of working, and the paper is an exemplification of a research practice, which seeks to let subjective and objective...

  15. Qualitative research, tourism

    DEFF Research Database (Denmark)

    Ren, Carina Bregnholm

    2016-01-01

    a range of methodologies, but is usually contrasted with and seen in opposition to quantitative and deductive research, as it attempts to explore the complexity and fragmentary nature of the social world of tourism. This exploration can be carried out through ethnographic fieldwork and/or by applying......Qualitative research, tourism Qualitative research refers to research applying a range of qualitative methods in order to inductively explore, interpret, and understand a given field or object under study. Qualitative research in tourism takes its inspiration primarily from the cultural and social...... ethnography (nethnography). More recently, attempts have been made to explore relations between the performing arts and social science, e.g. through innovative methods such as poetry and virtual curating. Ontology, epistemology and methodology As a multidisciplinary field, tourism research has incorporated...

  16. Research inequality in nanomedicine

    OpenAIRE

    Woodson, T. (Thomas)

    2012-01-01

    The 10-90 gap is an idea in the healthcare literature that less than 10% of all research funding goes to solving health problems that are 90% of the global disease burden. This paper examines whether there is inequality in nanotechnology healthcare research (nanomedicine). To understand the inequality in nanomedicine, I conducted a bibliometric review of Web of Science and PubMed databases. Overall there is not large inequality in nanomedicine research. The bibliometric analysis shows that mo...

  17. Mass media research

    OpenAIRE

    Meulemann, Heiner; Hagenah, Jörg

    2009-01-01

    "Mass media are defind as media which have their proper program and constitute their own audience. Mass media research, accordingly, deals with the production of programs and the consumption of the audience. For both perspectives, research topics are justified, data sources are introduced, and recommendation for the research infrastructure are given. As for media production, the establishment of a central media content archive is recommended where content analytic time series of public agenci...

  18. CME ON CLINICAL RESEARCH

    OpenAIRE

    Suneel. I. Majagi; S. S. Torgal; S. V. Hiremath

    2012-01-01

    Safety and efficacy are the two major concerns for any drug therapy. Globally clinical research plays an inevitable role in bringing a new molecule into the market after its synthesis by the pharmaceutical industries. Availability of large patient population, highly educated and skilled manpower, wide spectrum of diseases and favorable economic environment imply India’s potential as a global hub for clinical research. Pharmaceutical companies and Clinical Research Organization (CRO)s will req...

  19. 2016 Research Final Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Koskelo, EliseAnne Corinne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-16

    These are slides which show an example of research at Los Alamos National Laboratory done by E.C. Koskelo to show college professors in the hopes of earning a research position or fellowship position. In summary, this researcher developed a new in-situ technique for the inspection of additively manufactured parts, created an algorithm which can correct "skewed" scans of angular parts/taken at oblique angles, and used AWS to detect hidden defects and thickness changes in aerospace composites.

  20. Nuclear safety research

    International Nuclear Information System (INIS)

    According to the related rules of the Energy Office in the Ministry of Science and Technology, the NNSA signed the contracts for S and T Key Research Projects with 6 organizations separately about the research projects of the CEFR's nuclear safety regulation. The important research projects consists of 'The Accident Analysis and Major Accident Analysis on CEFR', 'HCDA Research on the CEFR', 'The Sodium-water Reaction Accident Analysis on CEFR's SG', 'The Regulations and Technical Documents on the CEFR', 'The Inspection Procedures on The Components Manufacturing and Installation of CEFR', etc