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Sample records for asdex upgrade enhancements

  1. The enhanced ASDEX Upgrade pellet centrifuge launcher

    SciTech Connect

    Plöckl, B.; Lang, P. T.

    2013-10-15

    Pellets played an important role in the program of ASDEX Upgrade serving both for investigations on efficient particle fuelling and high density scenarios but also for pioneering work on Edge Localised Mode (ELM) pacing and mitigation. Initially designed for launching fuelling pellets from the magnetic low field side, the system was converted already some time ago to inject pellets from the magnetic high field side as much higher fuelling efficiency was found using this configuration. In operation for more than 20 years, the pellet launching system had to undergo a major revision and upgrading, in particular of its control system. Furthermore, the control system installed adjacent to the launcher had to be transferred to a more distant location enforcing a complete galvanic separation from torus potential and a fully remote control solution. Changing from a hybrid system consisting of PLC S5/S7 and some hard wired relay control to a state of the art PLC system allowed the introduction of several new operational options enabling more flexibility in the pellet experiments. This article describes the new system architecture of control hardware and software, the operating procedure, and the extended operational window. First successful applications for ELM pacing and triggering studies are presented as well as utilization for the development of high density scenarios.

  2. The enhanced ASDEX Upgrade pellet centrifuge launcher.

    PubMed

    Plöckl, B; Lang, P T

    2013-10-01

    Pellets played an important role in the program of ASDEX Upgrade serving both for investigations on efficient particle fuelling and high density scenarios but also for pioneering work on Edge Localised Mode (ELM) pacing and mitigation. Initially designed for launching fuelling pellets from the magnetic low field side, the system was converted already some time ago to inject pellets from the magnetic high field side as much higher fuelling efficiency was found using this configuration. In operation for more than 20 years, the pellet launching system had to undergo a major revision and upgrading, in particular of its control system. Furthermore, the control system installed adjacent to the launcher had to be transferred to a more distant location enforcing a complete galvanic separation from torus potential and a fully remote control solution. Changing from a hybrid system consisting of PLC S5/S7 and some hard wired relay control to a state of the art PLC system allowed the introduction of several new operational options enabling more flexibility in the pellet experiments. This article describes the new system architecture of control hardware and software, the operating procedure, and the extended operational window. First successful applications for ELM pacing and triggering studies are presented as well as utilization for the development of high density scenarios. PMID:24182110

  3. Overview of ASDEX Upgrade results

    NASA Astrophysics Data System (ADS)

    Zohm, H.; Angioni, C.; Arslanbekov, R.; Atanasiu, C.; Becker, G.; Becker, W.; Behler, K.; Behringer, K.; Bergmann, A.; Bilato, R.; Bobkov, V.; Bolshukhin, D.; Bolzonella, T.; Borrass, K.; Brambilla, M.; Braun, F.; Buhler, A.; Carlson, A.; Conway, G. D.; Coster, D. P.; Drube, R.; Dux, R.; Egorov, S.; Eich, T.; Engelhardt, K.; Fahrbach, H.-U.; Fantz, U.; Faugel, H.; Finken, K. H.; Foley, M.; Franzen, P.; Fuchs, J. C.; Gafert, J.; Fournier, K. B.; Gantenbein, G.; Gehre, O.; Geier, A.; Gernhardt, J.; Goodman, T.; Gruber, O.; Gude, A.; Günter, S.; Haas, G.; Hartmann, D.; Heger, B.; Heinemann, B.; Herrmann, A.; Hobirk, J.; Hofmeister, F.; Hohenöcker, H.; Horton, L. D.; Igochine, V.; Jacchia, A.; Jakobi, M.; Jenko, F.; Kallenbach, A.; Kardaun, O.; Kaufmann, M.; Keller, A.; Kendl, A.; Kim, J.-W.; Kirov, K.; Kochergov, R.; Kollotzek, H.; Kraus, W.; Krieger, K.; Kurki-Suonio, T.; Kurzan, B.; Lang, P. T.; Lasnier, C.; Lauber, P.; Laux, M.; Leonard, A. W.; Leuterer, F.; Lohs, A.; Lorenz, A.; Lorenzini, R.; Maggi, C.; Maier, H.; Mank, K.; Manso, M.-E.; Mantica, P.; Maraschek, M.; Martines, E.; Mast, K.-F.; McCarthy, P.; Meisel, D.; Meister, H.; Meo, F.; Merkel, P.; Merkel, R.; Merkl, D.; Mertens, V.; Monaco, F.; Mück, A.; Müller, H. W.; Münich, M.; Murmann, H.; Na, Y.-S.; Neu, G.; Neu, R.; Neuhauser, J.; Nguyen, F.; Nishijima, D.; Nishimura, Y.; Noterdaeme, J.-M.; Nunes, I.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pinches, S. D.; Poli, E.; Proschek, M.; Pugno, R.; Quigley, E.; Raupp, G.; Reich, M.; Ribeiro, T.; Riedl, R.; Rohde, V.; Roth, J.; Ryter, F.; Saarelma, S.; Sandmann, W.; Savtchkov, A.; Sauter, O.; Schade, S.; Schilling, H.-B.; Schneider, W.; Schramm, G.; Schwarz, E.; Schweinzer, J.; Schweizer, S.; Scott, B. D.; Seidel, U.; Serra, F.; Sesnic, S.; Sihler, C.; Silva, A.; Sips, A. C. C.; Speth, E.; Stäbler, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Strumberger, E.; Suttrop, W.; Tabasso, A.; Tanga, A.; Tardini, G.; Tichmann, C.; Treutterer, W.; Troppmann, M.; Urano, H.; Varela, P.; Vollmer, O.; Wagner, D.; Wenzel, U.; Wesner, F.; Westerhof, E.; Wolf, R.; Wolfrum, E.; Würsching, E.; Yoon, S.-W.; Yu, Q.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.

    2003-12-01

    Recent results from the ASDEX Upgrade experimental campaigns 2001 and 2002 are presented. An improved understanding of energy and particle transport emerges in terms of a 'critical gradient' model for the temperature gradients. Coupling this to particle diffusion explains most of the observed behaviour of the density profiles, in particular, the finding that strong central heating reduces the tendency for density profile peaking. Internal transport barriers (ITBs) with electron and ion temperatures in excess of 20 keV (but not simultaneously) have been achieved. By shaping the plasma, a regime with small type II edge localized modes (ELMs) has been established. Here, the maximum power deposited on the target plates was greatly reduced at constant average power. Also, an increase of the ELM frequency by injection of shallow pellets was demonstrated. ELM free operation is possible in the quiescent H-mode regime previously found in DIII-D which has also been established on ASDEX Upgrade. Regarding stability, a regime with benign neoclassical tearing modes (NTMs) was found. During electron cyclotron current drive (ECCD) stabilization of NTMs, bgrN could be increased well above the usual onset level without a reappearance of the NTM. Electron cyclotron resonance heating and ECCD have also been used to control the sawtooth repetition frequency at a moderate fraction of the total heating power. The inner wall of the ASDEX Upgrade vessel has increasingly been covered with tungsten without causing detrimental effects on the plasma performance. Regarding scenario integration, a scenario with a large fraction of noninductively driven current (geq50%), but without ITB has been established. It combines improved confinement (tgrE/tgrITER98 ap 1.2) and stability (bgrN les 3.5) at high Greenwald fraction (ne/nGW ap 0.85) in steady state and with type II ELMy edge and would offer the possibility for long pulses with high fusion power at reduced current in ITER.

  4. Enhancement of the FIDA diagnostic at ASDEX Upgrade for velocity space tomography

    NASA Astrophysics Data System (ADS)

    Weiland, M.; Geiger, B.; Jacobsen, A. S.; Reich, M.; Salewski, M.; Odstrčil, T.; the ASDEX Upgrade Team

    2016-02-01

    Recent upgrades to the FIDA (fast-ion D-alpha) diagnostic at ASDEX Upgrade are discussed. The diagnostic has been extended from three to five line of sight arrays with different angles to the magnetic field, and a spectrometer redesign allows the simultaneous measurement of red- and blue-shifted parts of the Doppler spectrum. These improvements make it possible to reconstruct the 2D fast-ion velocity distribution f≤ft(E,{{v}\\parallel}/v\\right) from the FIDA measurements by tomographic inversion under a wide range of plasma parameters. Two applications of the tomography are presented: a comparison between the distributions resulting from 60 keV and 93 keV neutral beam injection and a velocity-space resolved study of fast-ion redistribution induced by a sawtooth crash inside and outside the sawtooth inversion radius.

  5. Overview of ASDEX Upgrade results

    NASA Astrophysics Data System (ADS)

    Gruber, O.; Bosch, H.-S.; Günter, S.; Herrmann, A.; Kallenbach, A.; Kaufmann, M.; Krieger, K.; Lackner, K.; Mertens, V.; Neu, R.; Ryter, F.; Schweinzer, J.; Stäbler, A.; Suttrop, W.; Wolf, R.; Asmussen, K.; Bard, A.; Becker, G.; Behler, K.; Behringer, K.; Bergmann, A.; Bessenrodt-Weberpals, M.; Borrass, K.; Braams, B.; Brambilla, M.; Brandenburg, R.; Braun, F.; Brinkschulte, H.; Brückner, R.; Brüsehaber, B.; Büchl, K.; Buhler, A.; Callaghan, H. P.; Carlson, A.; Coster, D. P.; Cupido, L.; de Peña Hempel, S.; Dorn, C.; Drube, R.; Dux, R.; Egorov, S.; Engelhardt, W.; Fahrbach, H.-U.; Fantz, U.; Feist, H.-U.; Franzen, P.; Fuchs, J. C.; Fussmann, G.; Gafert, J.; Gantenbein, G.; Gehre, O.; Geier, A.; Gernhardt, J.; Gubanka, E.; Gude, A.; Haas, G.; Hallatschek, K.; Hartmann, D.; Heinemann, B.; Herppich, G.; Herrmann, W.; Hofmeister, F.; Holzhauer, E.; Jacobi, D.; Kakoulidis, M.; Karakatsanis, N.; Kardaun, O.; Khutoretski, A.; Kollotzek, H.; Kötterl, S.; Kraus, W.; Kurzan, B.; Kyriakakis, G.; Lang, P. T.; Lang, R. S.; Laux, M.; Lengyel, L. L.; Leuterer, F.; Lorenz, A.; Maier, H.; Manso, M.; Maraschek, M.; Markoulaki, M.; Mast, K.-F.; McCarthy, P. J.; Meisel, D.; Meister, H.; Merkel, R.; Meskat, J. P.; Müller, H. W.; Münich, M.; Murmann, H.; Napiontek, B.; Neu, G.; Neuhauser, J.; Niethammer, M.; Noterdaeme, J.-M.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pinches, S.; Raupp, G.; Reinmüller, K.; Riedl, R.; Rohde, V.; Röhr, H.; Roth, J.; Salzmann, H.; Sandmann, W.; Schilling, H.-B.; Schlögl, D.; Schmidtmann, K.; Schneider, H.; Schneider, R.; Schneider, W.; Schramm, G.; Schweizer, S.; Schwörer, R. R.; Scott, B. D.; Seidel, U.; Serra, F.; Sesnic, S.; Sihler, C.; Silva, A.; Speth, E.; Steuer, K.-H.; Stober, J.; Streibl, B.; Thoma, A.; Treutterer, W.; Troppmann, M.; Tsois, N.; Ullrich, W.; Ulrich, M.; Varela, P.; Verbeek, H.; Vollmer, O.; Wedler, H.; Weinlich, M.; Wenzel, U.; Wesner, F.; Wunderlich, R.; Xantopoulos, N.; Yu, Q.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.; Zohm, H.; Zouhar, M.

    1999-09-01

    The closed ASDEX Upgrade Divertor II, `LYRA', is capable of handling heating powers of up to 20 MW or P/R of 12 MW/m, owing to a reduction of the maximum heat flux to the target plates by more than a factor of 2 compared with the open Divertor I. This reduction is caused by high radiative losses from carbon and hydrogen inside the divertor region and is in agreement with B2-EIRENE modelling predictions. At medium densities in the H mode, the type I ELM behaviour shows no dependence on the heating method (NBI, ICRH). ASDEX Upgrade-JET dimensionless identity experiments showed compatibility of the L-H transition with core physics constraints, while in the H mode confinement, inconsistencies with the invariance principle were established. At high densities close to the Greenwald density, the MHD limited edge pressures, the influence of divertor detachment on separatrix parameters and increasing edge transport lead to limited edge densities and finally to temperatures below the critical edge temperatures for H mode. This results in a drastic increase of the H mode threshold power and an upper H mode density limit with gas puff refuelling. The H mode confinement degradation approaching this density limit is caused by the ballooning mode limited edge pressures and `stiff' temperature profiles relating core and edge temperatures. Repetitive high field side pellet injection allows for H mode operation well above the Greenwald density; moreover, higher confinement than with gas fuelling is found up to the highest densities. Neoclassical tearing modes limit the achievable β depending on the collisionality at the resonant surface. In agreement with the polarization current model, the onset β is found to be proportional to the ion gyroradius in the collisionless regime, while higher collisionalities are stabilizing. The fractional energy loss connected with saturated modes at high pressures is about 25%. A reduction of neoclassical mode amplitude and an increase of β have

  6. Overview of ASDEX Upgrade results

    NASA Astrophysics Data System (ADS)

    Gruber, O.; Arslanbekov, R.; Atanasiu, C.; Bard, A.; Becker, G.; Becker, W.; Beckmann, M.; Behler, K.; Behringer, K.; Bergmann, A.; Bilato, R.; Bolshukin, D.; Borrass, K.; Bosch, H.-S.; Braams, B.; Brambilla, M.; Brandenburg, R.; Braun, F.; Brinkschulte, H.; Brückner, R.; Brüsehaber, B.; Büchl, K.; Buhler, A.; Bürbaumer, H.; Carlson, A.; Ciric, M.; Conway, G.; Coster, D. P.; Dorn, C.; Drube, R.; Dux, R.; Egorov, S.; Engelhardt, W.; Fahrbach, H.-U.; Fantz, U.; Faugel, H.; Foley, M.; Franzen, P.; Fu, P.; Fuchs, J. C.; Gafert, J.; Gantenbein, G.; Gehre, O.; Geier, A.; Gernhardt, J.; Gubanka, E.; Gude, A.; Günter, S.; Haas, G.; Hartmann, D.; Heinemann, B.; Herrmann, A.; Hobirk, J.; Hofmeister, F.; Hohenöcker, H.; Horton, L.; Hu, L.; Jacobi, D.; Jakobi, M.; Jenko, F.; Kallenbach, A.; Kardaun, O.; Kaufmann, M.; Kendl, A.; Kim, J.-W.; Kirov, K.; Kochergov, R.; Kollotzek, H.; Kraus, W.; Krieger, K.; Kurzan, B.; Kyriakakis, G.; Lackner, K.; Lang, P. T.; Lang, R. S.; Laux, M.; Lengyel, L.; Leuterer, F.; Lorenz, A.; Maier, H.; Mank, K.; Manso, M.-E.; Maraschek, M.; Mast, K.-F.; McCarthy, P. J.; Meisel, D.; Meister, H.; Meo, F.; Merkel, R.; Mertens, V.; Meskat, J. P.; Monk, R.; Müller, H. W.; Münich, M.; Murmann, H.; Neu, G.; Neu, R.; Neuhauser, J.; Noterdaeme, J.-M.; Nunes, I.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pinches, S.; Poli, E.; Pugno, R.; Raupp, G.; Ribeiro, T.; Riedl, R.; Riondato, S.; Rohde, V.; Röhr, H.; Roth, J.; Ryter, F.; Salzmann, H.; Sandmann, W.; Sarelma, S.; Schade, S.; Schilling, H.-B.; Schlögl, D.; Schmidtmann, K.; Schneider, R.; Schneider, W.; Schramm, G.; Schweinzer, J.; Schweizer, S.; Scott, B. D.; Seidel, U.; Serra, F.; Sesnic, S.; Sihler, C.; Silva, A.; Sips, A.; Speth, E.; Stäbler, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Strumberger, E.; Suttrop, W.; Tabasso, A.; Tanga, A.; Tardini, G.; Tichmann, C.; Treutterer, W.; Troppmann, M.; Tsois, N.; Ullrich, W.; Ulrich, M.; Varela, P.; Vollmer, O.; Wenzel, U.; Wesner, F.; Wolf, R.; Wolfrum, E.; Wunderlich, R.; Xantopoulos, N.; Yu, Q.; Zarrabian, M.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.; Zeiler, A.; Zohm, H.

    2001-10-01

    Ion and electron temperature profiles in conventional L and H mode on ASDEX Upgrade are generally stiff and limited by a critical temperature gradient length ∇T/T as given by ion temperature gradient (ITG) driven turbulence. ECRH experiments indicate that electron temperature (Te) profiles are also stiff, as predicted by electron temperature gradient turbulence with streamers. Accordingly, the core and edge temperatures are proportional to each other and the plasma energy is proportional to the pedestal pressure for fixed density profiles. Density profiles are not stiff, and confinement improves with density peaking. Medium triangularity shapes (δ<0.45) show strongly improved confinement up to the Greenwald density nGW and therefore higher βvalues, owing to increasing pedestal pressure, and H mode density operation extends above nGW. Density profile peaking at nGW was achieved with controlled gas puffing rates, and first results from a new high field side pellet launcher allowing higher pellet velocities are promising. At these high densities, small type II ELMs provide good confinement with low divertor power loading. In advanced scenarios the highest performance was achieved in the improved H mode with HL-89PβN approx 7.2 at δ = 0.3 for five confinement times, limited by neoclassical tearing modes (NTMs) at low central magnetic shear (qmin approx 1). The T profiles are still governed by ITG and trapped electron mode (TEM) turbulence, and confinement is improved by density peaking connected with low magnetic shear. Ion internal transport barrier (ITB) discharges - mostly with reversed shear (qmin>1) and L mode edge - achieved HL-89P <= 2.1 and are limited to βN <= 1.7 by internal and external ideal MHD modes. Turbulence driven transport is suppressed, in agreement with the E × B shear flow paradigm, and core transport coefficients are at the neoclassical ion transport level, where the latter was established by Monte Carlo simulations. Reactor relevant ion

  7. The tungsten divertor experiment at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Neu, R.; Asmussen, K.; Krieger, K.; Thoma, A.; Bosch, H.-S.; Deschka, S.; Dux, R.; Engelhardt, W.; García-Rosales, C.; Gruber, O.; Herrmann, A.; Kallenbach, A.; Kaufmann, M.; Mertens, V.; Ryter, F.; Rohde, V.; Roth, J.; Sokoll, M.; Stäbler, A.; Suttrop, W.; Weinlich, M.; Zohm, H.; Alexander, M.; Becker, G.; Behler, K.; Behringer, K.; Behrisch, R.; Bergmann, A.; Bessenrodt-Weberpals, M.; Brambilla, M.; Brinkschulte, H.; Büchl, K.; Carlson, A.; Chodura, R.; Coster, D.; Cupido, L.; de Blank, H. J.; de Peña Hempel, S.; Drube, R.; Fahrbach, H.-U.; Feist, J.-H.; Feneberg, W.; Fiedler, S.; Franzen, P.; Fuchs, J. C.; Fußmann, G.; Gafert, J.; Gehre, O.; Gernhardt, J.; Haas, G.; Herppich, G.; Herrmann, W.; Hirsch, S.; Hoek, M.; Hoenen, F.; Hofmeister, F.; Hohenöcker, H.; Jacobi, D.; Junker, W.; Kardaun, O.; Kass, T.; Kollotzek, H.; Köppendörfer, W.; Kurzan, B.; Lackner, K.; Lang, P. T.; Lang, R. S.; Laux, M.; Lengyel, L. L.; Leuterer, F.; Manso, M. E.; Maraschek, M.; Mast, K.-F.; McCarthy, P.; Meisel, D.; Merkel, R.; Müller, H. W.; Münich, M.; Murmann, H.; Napiontek, B.; Neu, G.; Neuhauser, J.; Niethammer, M.; Noterdaeme, J.-M.; Pasch, E.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pitcher, C. S.; Poschenrieder, W.; Raupp, G.; Reinmüller, K.; Riedl, R.; Röhr, H.; Salzmann, H.; Sandmann, W.; Schilling, H.-B.; Schlögl, D.; Schneider, H.; Schneider, R.; Schneider, W.; Schramm, G.; Schweinzer, J.; Scott, B. D.; Seidel, U.; Serra, F.; Speth, E.; Silva, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Treutterer, W.; Troppmann, M.; Tsois, N.; Ulrich, M.; Varela, P.; Verbeek, H.; Verplancke, Ph; Vollmer, O.; Wedler, H.; Wenzel, U.; Wesner, F.; Wolf, R.; Wunderlich, R.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.

    1996-12-01

    Tungsten-coated tiles, manufactured by plasma spray on graphite, were mounted in the divertor of the ASDEX Upgrade tokamak and cover almost 90% of the surface facing the plasma in the strike zone. Over 600 plasma discharges have been performed to date, around 300 of which were auxiliary heated with heating powers up to 10 MW. The production of tungsten in the divertor was monitored by a W I line at 400.8 nm. In the plasma centre an array of spectral lines at 5 nm emitted by ionization states around W XXX was measured. From the intensity of these lines the W content was derived. Under normal discharge conditions W-concentrations around 0741-3335/38/12A/013/img12 or even lower were found. The influence on the main plasma parameters was found to be negligible. The maximum concentrations observed decrease with increasing heating power. In several low power discharges accumulation of tungsten occurred and the temperature profile was flattened. The concentrations of the intrinsic impurities carbon and oxygen were comparable to the discharges with the graphite divertor. Furthermore, the density and the 0741-3335/38/12A/013/img13 limits remained unchanged and no negative influence on the energy confinement or on the H-mode threshold was found. Discharges with neon radiative cooling showed the same behaviour as in the graphite divertor case.

  8. The compact neutron spectrometer at ASDEX Upgrade

    SciTech Connect

    Giacomelli, L.; Zimbal, A.; Tittelmeier, K.; Schuhmacher, H.; Tardini, G.; Neu, R.; Collaboration: ASDEX Upgrade Team

    2011-12-15

    The first neutron spectrometer of ASDEX Upgrade (AUG) was installed in November 2008. It is a compact neutron spectrometer (CNS) based on a BC501A liquid scintillating detector, which can simultaneously measure 2.45-MeV and 14-MeV neutrons emitted from deuterium (D) plasmas and {gamma} radiation. The scintillating detector is coupled to a digital pulse shape discrimination data acquisition (DPSD) system capable of count rates up to 10{sup 6} s{sup -1}. The DPSD system can operate in acquisition and processing mode. With the latter n-{gamma} discrimination is performed off-line based on the two-gate method. The paper describes the tests of the CNS and its installation at AUG. The neutron emission from the D plasma measured during a discharge with high auxiliary heating power was used to validate the CNS performance. The study of the optimal settings for the DPSD data processing to maximize the n-{gamma} discrimination capability of the CNS is reported. The CNS measured both 2.45-MeV and 14-MeV neutrons emitted in AUG D plasmas with a maximum count rate of 5.4 x10{sup 5} s{sup -1} (>10 times higher than similar spectrometers previously achieved) with an efficiency of 9.3 x 10{sup -10} events per AUG neutron.

  9. Feedback-controlled NTM stabilization on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Stober, J.; Barrera, L.; Behler, K.; Bock, A.; Buhler, A.; Eixenberger, H.; Giannone, L.; Kasparek, W.; Maraschek, M.; Mlynek, A.; Monaco, F.; Poli, E.; Rapson, C. J.; Reich, M.; Schubert, M.; Treutterer, W.; Wagner, D.; Zohm, H.

    2015-03-01

    On ASDEX Upgrade a concept for real-time stabilization of NTMs has been realized and successfully applied to (3,2)- and (2,1)-NTMs. Since most of the work has meanwhile been published elsewhere, a short summary with the appropriate references is given. Limitations, deficits and future extensions of the system are discussed. In a second part the recent work on using modulated ECCD for NTM stabilisation is described in some detail. In these experiments ECCD power is modulated according to a magnetic footprint of the rotating NTM. In agreement with earlier results it could be shown that O-point heating reduces the necessary average power for stabilisation whereas X-point heating hampers stabilisation. Although this modulated scheme is not relevant for routine NTM stabilisation on ASDEX Upgrade it may be mandatory for ITER or DEMO. On ASDEX Upgrade it has been re-developed to demonstrate the usage of a FAst DIrectional Switch to continously heat the O-point of the rotating island with only one gyrotron switching between two launchers which target the mode at locations separated in phase by 180 degrees as described in [1].

  10. Enhancement of the Stabilization Efficiency of a Neoclassical Magnetic Island by Modulated Electron Cyclotron Current Drive in the ASDEX Upgrade Tokamak

    SciTech Connect

    Maraschek, M.; Yu, Q.; Zohm, H.; Guenter, S.; Leuterer, F.; Manini, A.; Gantenbein, G.

    2007-01-12

    The efficiency of generating a helical current in magnetic islands for the purpose of suppression of neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD) is studied experimentally in the ASDEX Upgrade tokamak. It is found that the efficiency of generating helical current by continuous current drive in a rotating island drops drastically as the width 2d of the co-ECCD driven current becomes larger than the island width W. However, by modulating the co-ECCD in phase with the rotating islands O point, the efficiency can be recovered. The results are in good agreement with theoretical calculations taking into account the equilibration of the externally driven current on the island flux surfaces. The result is especially important for large next-step fusion devices, such as ITER, where 2d>W is expected to be unavoidable during NTM suppression, suggesting that modulation capability should be foreseen.

  11. First results with 3-strap ICRF antennas in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Bobkov, V.; Braun, F.; Dux, R.; Herrmann, A.; Faugel, H.; Fünfgelder, H.; Kallenbach, A.; Neu, R.; Noterdaeme, J.-M.; Ochoukov, R.; Pütterich, Th.; Tuccilo, A.; Tudisco, O.; Wang, Y.; Yang, Q.; ASDEX Upgrade team

    2016-08-01

    The 3-strap antennas in ASDEX Upgrade allow ICRF operation with low tungsten (W) content in the confined plasma with W-coated antenna limiters. With the 3-strap antenna configuration, the local W impurity source at the antenna is drastically reduced and the core W concentration is similar to that of the boron coated 2-strap antenna at a given ICRF power. Operation of the 3-strap antennas with the power ratio between the central and the outer straps of 1.5:1 and 2:1 is adopted to minimize the ICRF-specific W release.

  12. Frequency hopping millimeter-wave reflectometry in ASDEX upgrade

    SciTech Connect

    Cupido, L.; Graca, S.; Conway, G. D.; Manso, M.; Serra, F.

    2006-10-15

    Millimeter-wave reflectometers for performing density fluctuations have traditionally used either tunable fixed frequency (heterodyne and homodyne) systems or multichannel fixed frequency arrangements. Only recently novel systems were brought into operation with the ability to hop from one frequency to another over a large bandwidth, during each plasma discharge, while retaining the quality of fixed frequency phase locked sources. The new broadband fast hopping millimeter-wave reflectometer incorporates frequency synthesizers for both plasma signal and local oscillators, and the receivers are heterodyne producing full phase/amplitude outputs. Two identical systems were recently installed in (ASDEX upgrade tokamak - IPP-MPG Germany) covering the Q band (33-50 GHz) and the V band (50-75 GHz). In the present article the system is described and the particular implementation on ASDEX, using monostatic antenna system, is presented showing the possibility of correlation studies in fully optimized antenna scenarios. With both Q and V channels in operation it was possible to devise several operation schemes that are described here and a result showing the radial localization of magnetohydrodynamic activity is also presented.

  13. Spectrally resolved motional Stark effect measurements on ASDEX Upgrade

    SciTech Connect

    Reimer, R.; Dinklage, A.; Wolf, R.; Fischer, R.; Hobirk, J.; Löbhard, T.; Mlynek, A.; Reich, M.; Sawyer, L.; Collaboration: ASDEX Upgrade

    2013-11-15

    A spectrally resolved Motional Stark Effect (MSE) diagnostic has been installed at ASDEX Upgrade. The MSE data have been fitted by a forward model providing access to information about the magnetic field in the plasma interior [R. Reimer, A. Dinklage, J. Geiger et al., Contrib. Plasma Phys. 50, 731–735 (2010)]. The forward model for the beam emission spectra comprises also the fast ion D{sub α} signal [W. W. Heidbrink and G. J. Sadler, Nucl. Fusion 34, 535–615 (1994)] and the smearing on the CCD-chip. The calculated magnetic field data as well as the revealed (dia)magnetic effects are consistent with the results from equilibrium reconstruction solver. Measurements of the direction of the magnetic field are affected by unknown and varying polarization effects in the observation.

  14. Real time capable infrared thermography for ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Sieglin, B.; Faitsch, M.; Herrmann, A.; Brucker, B.; Eich, T.; Kammerloher, L.; Martinov, S.

    2015-11-01

    Infrared (IR) thermography is widely used in fusion research to study power exhaust and incident heat load onto the plasma facing components. Due to the short pulse duration of today's fusion experiments, IR systems have mostly been designed for off-line data analysis. For future long pulse devices (e.g., Wendelstein 7-X, ITER), a real time evaluation of the target temperature and heat flux is mandatory. This paper shows the development of a real time capable IR system for ASDEX Upgrade. A compact IR camera has been designed incorporating the necessary magnetic and electric shielding for the detector, cooler assembly. The camera communication is based on the Camera Link industry standard. The data acquisition hardware is based on National Instruments hardware, consisting of a PXIe chassis inside and a fibre optical connected industry computer outside the torus hall. Image processing and data evaluation are performed using real time LabVIEW.

  15. Real time capable infrared thermography for ASDEX Upgrade

    SciTech Connect

    Sieglin, B. Faitsch, M.; Herrmann, A.; Brucker, B.; Eich, T.; Kammerloher, L.; Martinov, S.

    2015-11-15

    Infrared (IR) thermography is widely used in fusion research to study power exhaust and incident heat load onto the plasma facing components. Due to the short pulse duration of today’s fusion experiments, IR systems have mostly been designed for off-line data analysis. For future long pulse devices (e.g., Wendelstein 7-X, ITER), a real time evaluation of the target temperature and heat flux is mandatory. This paper shows the development of a real time capable IR system for ASDEX Upgrade. A compact IR camera has been designed incorporating the necessary magnetic and electric shielding for the detector, cooler assembly. The camera communication is based on the Camera Link industry standard. The data acquisition hardware is based on National Instruments hardware, consisting of a PXIe chassis inside and a fibre optical connected industry computer outside the torus hall. Image processing and data evaluation are performed using real time LabVIEW.

  16. Analysis of ICRF-Accelerated Ions in ASDEX Upgrade

    SciTech Connect

    Mantsinen, M. J.; Eriksson, L.-G.; Noterdaeme, J.-M.

    2007-09-28

    MHD-induced losses of fast ions with energy in the MeV range have been observed during high-power ICRF heating of hydrogen minority ions in the ASDEX Upgrade tokamak (R{sub 0}{approx_equal}1.65 m, a{approx_equal}0.5 m). ICRF heating and ICRF-driven fast ions in discharges exhibiting fast ion losses due to toroidal Alfven eigenmodes and a new core-localised MHD instability are analysed. It is found that the lost ions are ICRF-accelerated trapped protons with energy in the range of 0.3-1.6 MeV, orbit widths of 20-35 cm, and turning points at r/a>0.5 and at major radii close to the cyclotron resonance {omega} = {omega}{sub cH}(R). The presence of such protons is consistent with ICRF modelling.

  17. Structure and dynamics of sawteeth crashes in ASDEX Upgrade

    SciTech Connect

    Igochine, V.; Guenter, S.; Lackner, K.; Pereverzev, G.; Zohm, H.; Boom, J.; Classen, I.; Dumbrajs, O.

    2010-12-15

    The crash phase of the sawteeth in ASDEX Upgrade tokamak [Herrmann et al., Fusion Sci. Technol. 44(3), 569 (2003)] is investigated in detail in this paper by means of soft x-ray (SXR) and electron cyclotron emission (ECE) diagnostics. Analysis of precursor and postcursor (1,1) modes shows that the crash does not affect the position of the resonant surface q=1. Our experimental results suggest that sawtooth crash models should contain two ingredients to be consistent with experimental observations: (1) the (1,1) mode structure should survive the crash and (2) the flux changes should be small to preserve the position of the q=1 surface close to its original location. Detailed structure of the reconnection point was investigated with ECE imaging diagnostic. It is shown that reconnection starts locally. The expelled core is hot which is consistent with SXR tomography results. The observed results can be explained in the framework of a stochastic model.

  18. Structure and dynamics of sawteeth crashes in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Igochine, V.; Boom, J.; Classen, I.; Dumbrajs, O.; Günter, S.; Lackner, K.; Pereverzev, G.; Zohm, H.; ASDEX Upgrade Team

    2010-12-01

    The crash phase of the sawteeth in ASDEX Upgrade tokamak [Herrmann et al., Fusion Sci. Technol. 44(3), 569 (2003)] is investigated in detail in this paper by means of soft x-ray (SXR) and electron cyclotron emission (ECE) diagnostics. Analysis of precursor and postcursor (1,1) modes shows that the crash does not affect the position of the resonant surface q =1. Our experimental results suggest that sawtooth crash models should contain two ingredients to be consistent with experimental observations: (1) the (1,1) mode structure should survive the crash and (2) the flux changes should be small to preserve the position of the q =1 surface close to its original location. Detailed structure of the reconnection point was investigated with ECE imaging diagnostic. It is shown that reconnection starts locally. The expelled core is hot which is consistent with SXR tomography results. The observed results can be explained in the framework of a stochastic model.

  19. Real time capable infrared thermography for ASDEX Upgrade.

    PubMed

    Sieglin, B; Faitsch, M; Herrmann, A; Brucker, B; Eich, T; Kammerloher, L; Martinov, S

    2015-11-01

    Infrared (IR) thermography is widely used in fusion research to study power exhaust and incident heat load onto the plasma facing components. Due to the short pulse duration of today's fusion experiments, IR systems have mostly been designed for off-line data analysis. For future long pulse devices (e.g., Wendelstein 7-X, ITER), a real time evaluation of the target temperature and heat flux is mandatory. This paper shows the development of a real time capable IR system for ASDEX Upgrade. A compact IR camera has been designed incorporating the necessary magnetic and electric shielding for the detector, cooler assembly. The camera communication is based on the Camera Link industry standard. The data acquisition hardware is based on National Instruments hardware, consisting of a PXIe chassis inside and a fibre optical connected industry computer outside the torus hall. Image processing and data evaluation are performed using real time LabVIEW. PMID:26628130

  20. Low frequency sawtooth precursor activity in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Papp, G.; Pokol, G. I.; Por, G.; Magyarkuti, A.; Lazányi, N.; Horváth, L.; Igochine, V.; Maraschek, M.; ASDEX Upgrade Team

    2011-06-01

    This paper describes the precursor activity observed in the ASDEX Upgrade tokamak before sawtooth crashes in various neutral beam heated plasmas, utilizing the soft x-ray diagnostic. In addition to the well-known (m, n) = (1,1) internal kink mode and its harmonics, a lower frequency mode is studied in detail. Power modulation of this mode is found to correlate with the power modulation of the (1, 1) kink mode in the quasistationary intervals indicating possible nonlinear interaction. Throughout the studied sawtooth crashes, the power of the lower frequency mode rose by several orders of magnitude just before the crash. In addition to its temporal behaviour, its spatial structure was estimated and the most likely value was found to be (1, 1). A possible role of this mode in the mechanism of the sawtooth crash is discussed.

  1. Increasing NTM Stabilization Efficiency Using Modulated ECCD In ASDEX Upgrade

    SciTech Connect

    Manini, A.; Maraschek, M.; Yu, Q.; Guenter, S.; Leuterer, F.; Zohm, H.; Gantenbein, G.

    2007-09-28

    This paper reports on the experimental studies, performed in the tokamak ASDEX Upgrade, for increasing the efficiency in generating a helical current within magnetic islands with the purpose of suppressing neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD). It is shown that the efficiency of generating this current by continuous CD in a rotating island drops drastically as the width 2d of the co-ECCD driven current becomes larger than the islands size W. However, by modulating the co-ECCD in phase with the island's O-point, the efficiency is recovered. The results are in good agreement with theoretical calculations taking into account the equilibration of the externally driven current on the island flux surfaces. The result is especially important for large next-step fusion devices, such as ITER, where 2d>W is expected to be unavoidable during NTM suppression, indicating that modulation capability should be foreseen.

  2. The Thomson scattering systems of the ASDEX upgrade tokamak

    SciTech Connect

    Murmann, H.; Goetsch, S.; Roehr, H.; Salzmann, H.; Steuer, K.H. )

    1992-10-01

    The Thomson scattering system of the ASDEX upgrade (AUG) tokamak is described. One of the main objectives of AUG is to investigate plasma wall interaction in reactor relevant discharges with a magnetic divertor. The very successful Nd:YAG scattering system developed for its predecessor ASDEX, has been upgraded to give higher spatial and temporal resolution, reliability, and flexibility to different discharge conditions. The system consists of two independently operating devices, each using a cluster of six lasers: One measures the electron temperature and density along three possible vertical chords alternatively through the magnetic axis, or the inner or outer boundary layer; a second chord in the equatorial plane will always cover the magnetic center even in the case of considerable Shafranov shifts. An additional compact spectrometer has been designed for measurements with high radial resolution in the equatorial plane across the separatrix. A third system, using the laser beams for the vertical arrangement once again, has been designed for profile measurements in the energy deposition zone 2 cm above the outer divertor plate. Each laser is run at a repetition rate of 20 Hz and 1 J per pulse. A variety of synchronization modes are available, e.g., 20 Hz/6 J, 120 Hz/1 J etc., or repetitive bursts at 20 Hz. In this case the minimum delay between two pulses is presently limited to {approx}30 {mu}s by the existing data acquisition. This mode will be used for investigating fast phenomena such as sawteeth or disruptive instabilities. During the time intervals between the laser pulses the bremsstrahlung radiation (line integral) will be measured by the Thomson scattering detection system to calculate {ital Z}{sub eff}.

  3. First results of ion cyclotron resonance heating on ASDEX upgrade

    SciTech Connect

    Noterdaeme, J.; Hoffmann, C.; Brambilla, M.; Buechl, K.; Eberhagen, A.; Field, A.; Fuchs, C.; Gehre, O.; Gernhardt, J.; Gruber, O.; Haas, G.; Hermann, A.; Hofmeister, F.; Kallenbach, A.; Lieder, G.; Mertens, V.; Murmann, H.; de Pena Hempel, S.; Poschenrieder, W.; Richter, T.; Ryter, F.; Salmon, N.; Salzmann, H.; Schneider, W.; Wesner, F.; Zehrfeld, H.; Zohm, H. ); ASDEX Upgrade Team

    1994-10-15

    ASDEX Upgrade is equipped with an ICRH system consisting of 4 generators of 2 MW power each and 4 double loop antennas. The generators, tuneable in frequency from 30 to 120 MHz, cover several heating scenarios over a wide range of magnetic fields (1 T[lt]B[sub t][lt]3.9 T): minority heating of H and He[sub 3] and second harmonic heating of H and D. ICRH-heated discharges in ASDEX Upgrade were so far carried out mainly at 30 MHz and a magnetic field of 2 T (H minority in D and He). Peak powers of 2.4 MW and pulse length up to 2.5 s were achieved (total energy 3.75 MJ). In L-mode, the density on turn-on of the ICRH stays constant, or even decreases. The ratio of radiated power to total input power is unchanged (60% in an unboronized machine, 30% in a freshly boronized machine) between Ohmic and ICRH phases. The electron temperature increases with 0.9 MW from 1 to 1.25 keV, the loop voltage drops. Transitions to the H-mode were easily and reliably achieved with ICRH alone (necessary ICRH power as low as 0.9 MW) and the length of the ELMy H-mode phases was limited only by the applied ICRH pulse length (ELMy H-mode phases of up to 2 s were achieved). The paper presents further results on heating and confinement in L and H-mode, antenna and edge studies and on divertor measurements. Preliminary experiments, performed with a combination of H minority heating (30 MHz) and H second harmonic (60 MHz) in 600 kA He and D discharges (H minority in the 5 to 20% range) at 2 T, and with non-resonant heating (30 MHz and 60 MHz at 1.35 T) are briefly discussed.

  4. Recent ASDEX Upgrade research in support of ITER and DEMO

    NASA Astrophysics Data System (ADS)

    H. Zohmthe ASDEX Upgrade Team; the EUROfusion MST1 Team

    2015-10-01

    Recent experiments on the ASDEX Upgrade tokamak aim at improving the physics base for ITER and DEMO to aid the machine design and prepare efficient operation. Type I edge localized mode (ELM) mitigation using resonant magnetic perturbations (RMPs) has been shown at low pedestal collisionality (νped\\ast <0.4) . In contrast to the previous high ν* regime, suppression only occurs in a narrow RMP spectral window, indicating a resonant process, and a concomitant confinement drop is observed due to a reduction of pedestal top density and electron temperature. Strong evidence is found for the ion heat flux to be the decisive element for the L-H power threshold. A physics based scaling of the density at which the minimum PLH occurs indicates that ITER could take advantage of it to initiate H-mode at lower density than that of the final Q = 10 operational point. Core density fluctuation measurements resolved in radius and wave number show that an increase of R/LTe introduced by off-axis electron cyclotron resonance heating (ECRH) mainly increases the large scale fluctuations. The radial variation of the fluctuation level is in agreement with simulations using the GENE code. Fast particles are shown to undergo classical slowing down in the absence of large scale magnetohydrodynamic (MHD) events and for low heating power, but show signs of anomalous radial redistribution at large heating power, consistent with a broadened off-axis neutral beam current drive current profile under these conditions. Neoclassical tearing mode (NTM) suppression experiments using electron cyclotron current drive (ECCD) with feedback controlled deposition have allowed to test several control strategies for ITER, including automated control of (3,2) and (2,1) NTMs during a single discharge. Disruption mitigation studies using massive gas injection (MGI) can show an increased fuelling efficiency with high field side injection, but a saturation of the fuelling efficiency is observed at high injected

  5. Simulations of global electrostatic microinstabilities in ASDEX Upgrade discharges

    NASA Astrophysics Data System (ADS)

    Bottino, A.; Peeters, A. G.; Sauter, O.; Vaclavik, J.; Villard, L.

    2004-01-01

    Electrostatic microinstabilities in ion internal barrier (ITB) and H-mode discharges of the ASDEX Upgrade tokamak [O. Gruber, R. Arslanbekov, C. Atanasiu et al., Nucl. Fusion 41, 1369 (2001)] have been investigated with a full radius gyrokinetic code. The code models linear stability and includes the effect of an equilibrium radial electric field and trapped electrons. In order to simulate plasmas in experimental conditions [k⊥ρL˜O(1)], the long wavelength approximation in the quasineutrality equation has been replaced by a Padé expansion of the modified Bessel function. Results show that the E×B flow, induced by the radial electric field, changes the linear stability of the dominant ion temperature gradient modes. The electrostatic potential eddies are tilted by the sheared flow thus reducing the radial extent and the growth rate of modes. However, the finite value of the flow has a stabilizing effect too; the most unstable modes are shifted away from the unfavorable curvature region leading to lower linear growth rates. In addition to this at least two other mechanisms give an important contribution to the stabilization in the ITB region; the reverse shear profile itself and, to a lesser degree, the local value of the temperature ratio, τ=Te/Ti.

  6. Progress in controlling ICRF-edge interactions in ASDEX upgrade

    NASA Astrophysics Data System (ADS)

    Bobkov, Vl.; Jacquet, Ph.; Ochoukov, R.; Zhang, W.; Bilato, R.; Braun, F.; Carralero, D.; Colas, L.; Czarnecka, A.; Dux, R.; Faugel, H.; Fünfgelder, H.; Jacquot, J.; Křivská, A.; Lunt, T.; Milanesio, D.; Maggiora, R.; Meyer, O.; Monakhov, I.; Noterdaeme, J.-M.; Potzel, S.; Pütterich, Th.; Stepanov, I.

    2015-12-01

    RF measurements during variation of the strap voltage balance of the original 2-strap ICRF antenna in ASDEX Upgrade at constant power are consistent with electromagnetic calculations by HFSS and TOPICA, more so for the latter. RF image current compensation is observed at the antenna limiters in the experiment at a local strap voltage of about half of the value of the remote strap, albeit with a non-negligible uncertainty in phasing. The RF-specific tungsten (W) source at the broad-limiter 2-strap antenna correlates strongly with the RF voltage at the local strap at the locations not connected to opposite side of the antenna along magnetic field lines. The trends of the observed increase of the RF loading with injection of local gas are well described by a combined EMC3-Eirene - FELICE calculations, with the most efficient improvement confirmed for the outer-midplane valves, but underestimated by about 1/3. The corresponding deuterium density tailoring is also likely responsible for the decrease of local W sources observed in the experiment.

  7. Application of AXUV diode detectors at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Bernert, M.; Eich, T.; Burckhart, A.; Fuchs, J. C.; Giannone, L.; Kallenbach, A.; McDermott, R. M.; Sieglin, B.

    2014-03-01

    In the ASDEX Upgrade tokamak, a radiation measurement for a wide spectral range, based on semiconductor detectors, with 256 lines of sight and a time resolution of 5μs was recently installed. In combination with the foil based bolometry, it is now possible to estimate the absolutely calibrated radiated power of the plasma on fast timescales. This work introduces this diagnostic based on AXUV (Absolute eXtended UltraViolet) n-on-p diodes made by International Radiation Detectors, Inc. The measurement and the degradation of the diodes in a tokamak environment is shown. Even though the AXUV diodes are developed to have a constant sensitivity for all photon energies (1 eV-8 keV), degradation leads to a photon energy dependence of the sensitivity. The foil bolometry, which is restricted to a time resolution of less than 1 kHz, offers a basis for a time dependent calibration of the diodes. The measurements of the quasi-calibrated diodes are compared with the foil bolometry and found to be accurate on the kHz time scale. Therefore, it is assumed, that the corrected values are also valid for the highest time resolution (200 kHz). With this improved diagnostic setup, the radiation induced by edge localized modes is analyzed on fast timescales.

  8. Application of AXUV diode detectors at ASDEX Upgrade.

    PubMed

    Bernert, M; Eich, T; Burckhart, A; Fuchs, J C; Giannone, L; Kallenbach, A; McDermott, R M; Sieglin, B

    2014-03-01

    In the ASDEX Upgrade tokamak, a radiation measurement for a wide spectral range, based on semiconductor detectors, with 256 lines of sight and a time resolution of 5 μs was recently installed. In combination with the foil based bolometry, it is now possible to estimate the absolutely calibrated radiated power of the plasma on fast timescales. This work introduces this diagnostic based on AXUV (Absolute eXtended UltraViolet) n-on-p diodes made by International Radiation Detectors, Inc. The measurement and the degradation of the diodes in a tokamak environment is shown. Even though the AXUV diodes are developed to have a constant sensitivity for all photon energies (1 eV-8 keV), degradation leads to a photon energy dependence of the sensitivity. The foil bolometry, which is restricted to a time resolution of less than 1 kHz, offers a basis for a time dependent calibration of the diodes. The measurements of the quasi-calibrated diodes are compared with the foil bolometry and found to be accurate on the kHz time scale. Therefore, it is assumed, that the corrected values are also valid for the highest time resolution (200 kHz). With this improved diagnostic setup, the radiation induced by edge localized modes is analyzed on fast timescales. PMID:24689581

  9. Application of AXUV diode detectors at ASDEX Upgrade

    SciTech Connect

    Bernert, M. Eich, T.; Burckhart, A.; Fuchs, J. C.; Giannone, L.; Kallenbach, A.; McDermott, R. M.; Sieglin, B.

    2014-03-15

    In the ASDEX Upgrade tokamak, a radiation measurement for a wide spectral range, based on semiconductor detectors, with 256 lines of sight and a time resolution of 5μs was recently installed. In combination with the foil based bolometry, it is now possible to estimate the absolutely calibrated radiated power of the plasma on fast timescales. This work introduces this diagnostic based on AXUV (Absolute eXtended UltraViolet) n-on-p diodes made by International Radiation Detectors, Inc. The measurement and the degradation of the diodes in a tokamak environment is shown. Even though the AXUV diodes are developed to have a constant sensitivity for all photon energies (1 eV-8 keV), degradation leads to a photon energy dependence of the sensitivity. The foil bolometry, which is restricted to a time resolution of less than 1 kHz, offers a basis for a time dependent calibration of the diodes. The measurements of the quasi-calibrated diodes are compared with the foil bolometry and found to be accurate on the kHz time scale. Therefore, it is assumed, that the corrected values are also valid for the highest time resolution (200 kHz). With this improved diagnostic setup, the radiation induced by edge localized modes is analyzed on fast timescales.

  10. First neutron spectrometry measurements in the ASDEX Upgrade tokamak

    NASA Astrophysics Data System (ADS)

    Tardini, G.; Zimbal, A.; Esposito, B.; Gagnon-Moisan, F.; Marocco, D.; Neu, R.; Schuhmacher, H.; the ASDEX Upgrade Team

    2012-03-01

    A compact neutron spectrometer based on the liquid scintillator BC501A has been installed on the ASDEX Upgrade tokamak. The aim is to measure neutron energy distribution functions as footprints of fast ions distribution functions, generated mainly via Neutral Beam Injection (NBI) in present day tokamaks. A flexible and fast software has been developed to perform digital pulse shape separation and to evaluate pulse height spectra. First measurements of count rates and pulse height spectra show a good signal to noise ratio for integration times comparable to the NBI slowing down time and to the energy confinement time. Due to the perpendicular line of sight, D-d fusion with perpendicular NBI is detected more efficiently and the line broadening of the 2.45 MeV neutrons is higher. Ion Cyclotron Resonance Heating (ICRH) combined to NBI exhibits a synergy effect, with count rates higher than the sum of the counts due to NBI and ICRH separately. Although the collimator is designed to screen gammas as much as possible, some qualitative gamma analysis is also possible, providing information in case of runaway electrons during disruptions. The experimental campaign for the characterisation of the system (detector + acquisition system) is complete and the determination of the response function is in progress.

  11. Real-time diamagnetic flux measurements on ASDEX Upgrade.

    PubMed

    Giannone, L; Geiger, B; Bilato, R; Maraschek, M; Odstrčil, T; Fischer, R; Fuchs, J C; McCarthy, P J; Mertens, V; Schuhbeck, K H

    2016-05-01

    Real-time diamagnetic flux measurements are now available on ASDEX Upgrade. In contrast to the majority of diamagnetic flux measurements on other tokamaks, no analog summation of signals is necessary for measuring the change in toroidal flux or for removing contributions arising from unwanted coupling to the plasma and poloidal field coil currents. To achieve the highest possible sensitivity, the diamagnetic measurement and compensation coil integrators are triggered shortly before plasma initiation when the toroidal field coil current is close to its maximum. In this way, the integration time can be chosen to measure only the small changes in flux due to the presence of plasma. Two identical plasma discharges with positive and negative magnetic field have shown that the alignment error with respect to the plasma current is negligible. The measured diamagnetic flux is compared to that predicted by TRANSP simulations. The poloidal beta inferred from the diamagnetic flux measurement is compared to the values calculated from magnetic equilibrium reconstruction codes. The diamagnetic flux measurement and TRANSP simulation can be used together to estimate the coupled power in discharges with dominant ion cyclotron resonance heating. PMID:27250425

  12. Progress in controlling ICRF-edge interactions in ASDEX upgrade

    SciTech Connect

    Bobkov, Vl. Ochoukov, R.; Bilato, R.; Braun, F.; Carralero, D.; Dux, R.; Faugel, H.; Fünfgelder, H.; Jacquot, J.; Lunt, T.; Potzel, S.; Pütterich, Th.; Jacquet, Ph.; Monakhov, I.; Zhang, W.; Noterdaeme, J.-M.; Stepanov, I.; Colas, L.; Meyer, O.; Czarnecka, A.; and others

    2015-12-10

    RF measurements during variation of the strap voltage balance of the original 2-strap ICRF antenna in ASDEX Upgrade at constant power are consistent with electromagnetic calculations by HFSS and TOPICA, more so for the latter. RF image current compensation is observed at the antenna limiters in the experiment at a local strap voltage of about half of the value of the remote strap, albeit with a non-negligible uncertainty in phasing. The RF-specific tungsten (W) source at the broad-limiter 2-strap antenna correlates strongly with the RF voltage at the local strap at the locations not connected to opposite side of the antenna along magnetic field lines. The trends of the observed increase of the RF loading with injection of local gas are well described by a combined EMC3-Eirene – FELICE calculations, with the most efficient improvement confirmed for the outer-midplane valves, but underestimated by about 1/3. The corresponding deuterium density tailoring is also likely responsible for the decrease of local W sources observed in the experiment.

  13. Carbon influx studies in the main chamber of ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Pütterich, T.; Dux, R.; Gafert, J.; Kallenbach, A.; Neu, R.; Pugno, R.; Yoon, S. W.; ASDEX Upgrade Team

    2003-10-01

    Carbon sources in the main chamber of ASDEX Upgrade, especially the 12 guard limiters at the low field side (LFS), were determined spectroscopically using recently installed lines of sight. Absolute photon fluxes were measured for spectral lines in the visible wavelength range referring to all spin systems of C+1 and C+2. A simple transport model for carbon enabled the simulation of the radial distribution of carbon radiation and the determination of the effective inverse photon efficiency, which was used for the evaluation of ion fluxes. The model also predicts the fraction of eroded particles that are transported out of the plasma before further ionization occurs. Comparison of the calculated losses with measurements showed good agreement in L-mode cases, whereas in H-mode cases the CIII/CII radiation ratio was too high by a factor 1.5. The contribution of each spin system to the ion flux was independently measured. For C+1 and C+2 the spin system distribution was found to be close to equilibrium. The line-of-sight-integrated photon fluxes were spatially separated for many lines of sight by Zeeman-analysis and differential measurements. This allowed us to determine the total influx from the high field side and LFS. Surprisingly, the carbon source at the inner heatshield was larger than the carbon influx from the limiter source at the LFS. This is very pronounced for the H-mode case investigated, where 60-80% of the carbon atoms emerge from the heatshield. This source is due to recycling or re-erosion of carbon, which probably originates from the limiters, because ap85% of the heatshield area consisted of tungsten coated tiles.

  14. H-mode filament studies with reflectometry in ASDEX upgrade

    NASA Astrophysics Data System (ADS)

    Vicente, J.; Conway, G. D.; Manso, M. E.; Müller, H. W.; Silva, C.; da Silva, F.; Guimarãis, L.; Silva, A.

    2014-12-01

    Broadband swept (i.e. frequency modulation of the continuous wave; FM-CW) and fixed frequency reflectometry (FFR) were used for the first time to study plasma filamentary activity; experiments were performed in ELMy H-mode plasmas at the ASDEX Upgrade tokamak. Electron density profiles were studied with FM-CW providing a first insight into filamentary activity and enabling us to localize the density layers probed with FFR. A novel filament detection technique was developed using a threshold criterion on the phase derivative signals from FFR. This technique was applied together with conditional averaging in measurements performed in the vicinity of the separatrix. Results showed good agreement with data from Langmuir probes and it was found that the majority of filaments propagate with dominant poloidal velocity in both periods of in-between edge localized modes (ELMs) (Vθ ≈ 575 m s-1) and at the ELM onset (Vθ ≈ 1180 m s-1). A time delay between the maximum filament activity at the outer mid-plane and the ELM peak at the inner divertor currents (≈ -461  ±  50 μs) agrees with expected time scales for the ELM lifetime. In inter-ELM periods we were able to estimate typical poloidal and toroidal sizes of filaments (Sθ ≈ [5.75-11.50] cm and Sϕ ≈ [33-66] cm) and a magnetohydrodynamic mode structure emerged from the measurements with poloidal and toroidal mode numbers (m ≈ [8-12] and n ≈ [2, 3]) in the range of possible peeling-ballooning modes.

  15. Chapter 9: Performance-Limiting MHD Activity and Possibilities for Its Stabilization in ASDEX Upgrade

    SciTech Connect

    Guenter, Sibylle; Zohm, Hartmut

    2003-11-15

    Performance-limiting magnetohydrodynamic (MHD) instabilities on ASDEX Upgrade are discussed. In the conventional H-mode scenario, the main MHD performance limitation is found to be the neoclassical tearing mode (NTM). The onset {beta} of NTMs in ASDEX Upgrade scales with the poloidal ion gyroradius, in agreement with theoretical expectations. At higher {beta} values, NTMs occur in a more benign form, the frequently-interrupted-regime NTMs, which lead to a smaller confinement degradation than normal NTMs. Active control of NTMs by electron cyclotron current drive in the island has been demonstrated on ASDEX Upgrade. In advanced tokamak regimes with reversed shear, a variety of performance-limiting instabilities has been observed. The shear reversal zone can be unstable to double tearing modes or to infernal modes; both have been identified in ASDEX Upgrade. Due to the broad current profile in advanced tokamak discharges, the ideal external kink mode can be unstable at relatively low {beta}{sub N} {<=} 2; this is a main limitation to strongly reversed shear discharges with peaked pressure profiles. Finally, it is shown that fast-particle-driven modes such as fishbones can also have beneficial effects, such as providing stationary current profiles or triggering internal transport barriers.

  16. A compact lithium pellet injector for tokamak pedestal studies in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Arredondo Parra, R.; Moreno Quicios, R.; Ploeckl, B.; Birkenmeier, G.; Herrmann, A.; Kocsis, G.; Laggner, F. M.; Lang, P. T.; Lunt, T.; Macian-Juan, R.; Rohde, V.; Sellmair, G.; Szepesi, T.; Wolfrum, E.; Zeidner, W.; Neu, R.

    2016-02-01

    Experiments have been performed at ASDEX Upgrade, aiming to investigate the impact of lithium in an all-metal-wall tokamak and attempting to enhance the pedestal operational space. For this purpose, a lithium pellet injector has been developed, capable of injecting pellets carrying a particle content ranging from 1.82 × 1019 atoms (0.21 mg) to 1.64 × 1020 atoms (1.89 mg). The maximum repetition rate is about 2 Hz. Free flight launch from the torus outboard side without a guiding tube was realized. In such a configuration, angular dispersion and speed scatter are low, and a transfer efficiency exceeding 90% was achieved in the test bed. Pellets are accelerated in a gas gun; hence special care was taken to avoid deleterious effects by the propellant gas pulse. Therefore, the main plasma gas species was applied as propellant gas, leading to speeds ranging from 420 m/s to 700 m/s. In order to minimize the residual amount of gas to be introduced into the plasma vessel, a large expansion volume equipped with a cryopump was added into the flight path. In view of the experiments, an optimal propellant gas pressure of 50 bars was chosen for operation, since at this pressure maximum efficiency and low propellant gas flux coincide. This led to pellet speeds of 585 m/s ± 32 m/s. Lithium injection has been achieved at ASDEX Upgrade, showing deep pellet penetration into the plasma, though pedestal broadening has not been observed yet.

  17. A compact lithium pellet injector for tokamak pedestal studies in ASDEX Upgrade.

    PubMed

    Arredondo Parra, R; Moreno Quicios, R; Ploeckl, B; Birkenmeier, G; Herrmann, A; Kocsis, G; Laggner, F M; Lang, P T; Lunt, T; Macian-Juan, R; Rohde, V; Sellmair, G; Szepesi, T; Wolfrum, E; Zeidner, W; Neu, R

    2016-02-01

    Experiments have been performed at ASDEX Upgrade, aiming to investigate the impact of lithium in an all-metal-wall tokamak and attempting to enhance the pedestal operational space. For this purpose, a lithium pellet injector has been developed, capable of injecting pellets carrying a particle content ranging from 1.82 × 10(19) atoms (0.21 mg) to 1.64 × 10(20) atoms (1.89 mg). The maximum repetition rate is about 2 Hz. Free flight launch from the torus outboard side without a guiding tube was realized. In such a configuration, angular dispersion and speed scatter are low, and a transfer efficiency exceeding 90% was achieved in the test bed. Pellets are accelerated in a gas gun; hence special care was taken to avoid deleterious effects by the propellant gas pulse. Therefore, the main plasma gas species was applied as propellant gas, leading to speeds ranging from 420 m/s to 700 m/s. In order to minimize the residual amount of gas to be introduced into the plasma vessel, a large expansion volume equipped with a cryopump was added into the flight path. In view of the experiments, an optimal propellant gas pressure of 50 bars was chosen for operation, since at this pressure maximum efficiency and low propellant gas flux coincide. This led to pellet speeds of 585 m/s ± 32 m/s. Lithium injection has been achieved at ASDEX Upgrade, showing deep pellet penetration into the plasma, though pedestal broadening has not been observed yet. PMID:26931850

  18. Upgrade to the control system of the reflectometry diagnostic of ASDEX upgrade

    NASA Astrophysics Data System (ADS)

    Graça, S.; Santos, J.; Manso, M. E.

    2004-10-01

    The broadband frequency modulation-continuous wave microwave/millimeter wave reflectometer of ASDEX upgrade tokamak (Institut für Plasma Physik (IPP), Garching, Germany) developed by Centro de Fusão Nuclear (Lisboa, Portugal) with the collaboration of IPP, is a complex system with 13 channels (O and X modes) and two types of operation modes (swept and fixed frequency). The control system that ensures remote operation of the diagnostic incorporates VME and CAMAC bus based acquisition/timing systems. Microprocessor input/output boards are used to control and monitor the microwave circuitry and associated electronic devices. The implementation of the control system is based on an object-oriented client/server model: a centralized server manages the hardware and receives input from remote clients. Communication is handled through transmission control protocol/internet protocol sockets. Here we describe recent upgrades of the control system aiming to: (i) accommodate new channels; (ii) adapt to the heterogeneity of computing platforms and operating systems; and (iii) overcome remote access restrictions. Platform and operating system independence was achieved by redesigning the graphical user interface in JAVA. As secure shell is the standard remote access protocol adopted in major fusion laboratories, secure shell tunneling was implemented to allow remote operation of the diagnostic through the existing firewalls.

  19. Edge and core Thomson scattering systems and their calibration on the ASDEX Upgrade tokamak

    SciTech Connect

    Kurzan, B.; Murmann, H. D.

    2011-10-15

    A new 10 channel Thomson scattering (TS) system was installed on the ASDEX Upgrade tokamak to measure radial profiles of electron density and temperature at the plasma edge with high radial resolution. Together with the already existing TS system, which is now used for the core plasma, electron density and temperature profiles extending from the edge to the core are now obtained in a single discharge. The TS systems are relatively calibrated by an optical parametric oscillator.

  20. Solid tungsten Divertor-III for ASDEX Upgrade and contributions to ITER

    NASA Astrophysics Data System (ADS)

    Herrmann, A.; Greuner, H.; Jaksic, N.; Balden, M.; Kallenbach, A.; Krieger, K.; de Marné, P.; Rohde, V.; Scarabosio, A.; Schall, G.; the ASDEX Upgrade Team

    2015-06-01

    ASDEX Upgrade became a full tungsten experiment in 2007 by coating its graphite plasma facing components with tungsten. In 2013 a redesigned solid tungsten divertor, Div-III, was installed and came into operation in 2014. The redesign of the outer divertor geometry provided the opportunity to increase the pumping efficiency in the lower divertor by increasing the gap between divertor and vessel. In parallel, a by-pass was installed into the cryo-pump in the divertor region allowing adapting of the pumping speed to the required edge density. Safe divertor operation and heat removal becomes more and more significant for future fusion devices. This requires developing ‘tools’ for divertor heat load control and to optimize the divertor design. The new divertor manipulator, DIM-II, allows retracting a relevant part of the outer divertor into a target exchange box without venting ASDEX Upgrade. Different front-ends can be installed and exposed to the plasma. At present, front-ends for probe exposition, gas puffing, electrical probes and actively cooled prototype targets are under construction. The installation of solid tungsten, the control of the pumping speed and the flexibility for testing divertor modifications on a weekly base is a unique feature of ASDEX Upgrade and offers together with the extended set of diagnostics the possibility to investigate dedicated questions for a future divertor design.

  1. Dual array 3D electron cyclotron emission imaging at ASDEX Upgrade

    SciTech Connect

    Classen, I. G. J. Bogomolov, A. V.; Domier, C. W.; Luhmann, N. C.; Suttrop, W.; Boom, J. E.; Tobias, B. J.; Donné, A. J. H.

    2014-11-15

    In a major upgrade, the (2D) electron cyclotron emission imaging diagnostic (ECEI) at ASDEX Upgrade has been equipped with a second detector array, observing a different toroidal position in the plasma, to enable quasi-3D measurements of the electron temperature. The new system will measure a total of 288 channels, in two 2D arrays, toroidally separated by 40 cm. The two detector arrays observe the plasma through the same vacuum window, both under a slight toroidal angle. The majority of the field lines are observed by both arrays simultaneously, thereby enabling a direct measurement of the 3D properties of plasma instabilities like edge localized mode filaments.

  2. Dual array 3D electron cyclotron emission imaging at ASDEX Upgrade.

    PubMed

    Classen, I G J; Domier, C W; Luhmann, N C; Bogomolov, A V; Suttrop, W; Boom, J E; Tobias, B J; Donné, A J H

    2014-11-01

    In a major upgrade, the (2D) electron cyclotron emission imaging diagnostic (ECEI) at ASDEX Upgrade has been equipped with a second detector array, observing a different toroidal position in the plasma, to enable quasi-3D measurements of the electron temperature. The new system will measure a total of 288 channels, in two 2D arrays, toroidally separated by 40 cm. The two detector arrays observe the plasma through the same vacuum window, both under a slight toroidal angle. The majority of the field lines are observed by both arrays simultaneously, thereby enabling a direct measurement of the 3D properties of plasma instabilities like edge localized mode filaments. PMID:25430246

  3. 3D simulations of gas puff effects on edge density and ICRF coupling in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Bobkov, V.; Lunt, T.; Noterdaeme, J.-M.; Coster, D.; Bilato, R.; Jacquet, P.; Brida, D.; Feng, Y.; Wolfrum, E.; Guimarais, L.; the ASDEX Upgrade Team

    2016-03-01

    In recent experiments, a local gas puff was found to be an effective way to tailor the scrape-off layer (SOL) density and improve the ion cyclotron range of frequency (ICRF) power coupling in tokamaks. In order to quantitatively reproduce these experiments, to understand the corresponding physics and to optimize the gas valve positions and rates, simulations were carried out with the 3D edge plasma transport code EMC3-EIRENE in ASDEX Upgrade. An inter-ELM phase of an H-mode discharge with a moderate gas puff rate (1.2  ×  1022 electrons s-1) is used in our simulations. We simulated cases with gas puff in the lower divertor, the outer mid-plane and the top of the machine while keeping other conditions the same. Compared with the lower divertor gas puff, the outer mid-plane gas puff can increase the local density in front of the antennas most effectively, while a toroidally uniform but significantly smaller enhancement is found for the top gas puff. Good agreement between our simulations and experiments is obtained. With further simulations, the mechanisms of SOL density tailoring via local gas puffing and the strategies of gas puff optimization are discussed in the paper.

  4. Simulations of gas puff effects on edge density and ICRF coupling in ASDEX upgrade using EMC3-Eirene

    SciTech Connect

    Zhang, W.; Lunt, T.; Bobkov, V.; Coster, D.; Brida, D.; Noterdaeme, J.-M.; Jacquet, P.; Feng, Y.

    2015-12-10

    Simulations were carried out with the 3D plasma transport code EMC3-EIRENE, to study the deuterium gas (D{sub 2}) puff effects on edge density and the coupling of Ion Cyclotron Range of Frequency (ICRF) power in ASDEX Upgrade. Firstly we simulated an inter-ELM phase of an H-mode discharge with a moderate (1.2 × 10{sup 22} electrons/s) lower divertor gas puff. Then we changed the gas source positions to the mid-plane or top of machine while keeping other conditions the same. Cases with different mid-plane or top gas valves are investigated. Our simulations indicate that compared to lower divertor gas puffing, the mid-plane gas puff can enhance the local density in front of the antennas most effectively, while a rather global (toroidally uniform) but significantly smaller enhancement is found for top gas puffing. Our results show quantitative agreement with the experiments.

  5. Status, Operation, and Extension of the ECRH System at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Wagner, D.; Stober, J.; Leuterer, F.; Monaco, F.; Müller, S.; Münich, M.; Rapson, C. J.; Reich, M.; Schubert, M.; Schütz, H.; Treutterer, W.; Zohm, H.; Thumm, M.; Scherer, T.; Meier, A.; Gantenbein, G.; Jelonnek, J.; Kasparek, W.; Lechte, C.; Plaum, B.; Goodman, T.; Litvak, A. G.; Denisov, G. G.; Chirkov, A.; Zapevalov, V.; Malygin, V.; Popov, L. G.; Nichiporenko, V. O.; Myasnikov, V. E.; Tai, E. M.; Solyanova, E. A.; Malygin, S. A.

    2016-01-01

    The upgraded electron cyclotron resonance heating (ECRH) system at ASDEX Upgrade (AUG) has been routinely used with eight gyrotrons during the last experimental campaign. A further upgrade will replace the existing system of four short-pulse (140 GHz, 2 s, 500 kW) gyrotrons. The final goal is to have around 6.5-7 MW at 140 GHz (or 5.5 MW at 105 GHz) from eight units available in the plasma during the whole AUG discharge (10 s). The system operates at 140 and 105 GHz with X2, O2 and X3 schemes. For B > 3 T also an ITER-like O1-scenario can be run using the 105 GHz option. Four of the eight launching antennas are capable of fast poloidal movements necessary for real-time control of the location of power deposition.

  6. Effect of 3D magnetic perturbations on the plasma rotation in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Martitsch, A. F.; Kasilov, S. V.; Kernbichler, W.; Kapper, G.; Albert, C. G.; Heyn, M. F.; Smith, H. M.; Strumberger, E.; Fietz, S.; Suttrop, W.; Landreman, M.; The ASDEX Upgrade Team; the EUROfusion MST1 Team

    2016-07-01

    The toroidal torque due to the non-resonant interaction with external magnetic perturbations (TF ripple and perturbations from ELM mitigation coils) in ASDEX Upgrade is modelled with help of the NEO-2 and SFINCS codes and compared to semi-analytical models. It is shown that almost all non-axisymmetric transport regimes contributing to neoclassical toroidal viscosity (NTV) are realized within a single discharge at different radial positions. The NTV torque is obtained to be roughly a quarter of the NBI torque. This indicates the presence of other important momentum sources. The role of these momentum sources and possible integral torque balance measurements are briefly discussed.

  7. Velocimetry analysis of type-I edge localized mode precursors in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Manz, P.; Boom, J. E.; Wolfrum, E.; Birkenmeier, G.; Classen, I. G. J.; Luhmann, N. C., Jr.; Stroth, U.; the ASDEX Upgrade Team

    2014-03-01

    When the electron transport barrier remains in its final shape before a type-I edge localized mode (ELM) crash in ASDEX Upgrade, ELM precursors appear as electron temperature fluctuations. In order to relate these precursors to an instability, spatial scales, parity and the cross-phase between electron temperature and radial velocity fluctuations are evaluated by means of velocimetry of measured 2D electron temperature fluctuations. A comprehensive comparison with properties of different instabilities points to microtearing modes. Bispectral analysis indicates a nonlinear coupling of these precursors to a ballooning-type mode prior to the ELM onset.

  8. ELM behaviour and linear MHD stability of edge ECRH heated ASDEX Upgrade plasmas

    NASA Astrophysics Data System (ADS)

    Burckhart, A.; Dunne, M.; Wolfrum, E.; Fischer, R.; McDermott, R.; Viezzer, E.; Willensdorfer, M.; the ASDEX Upgrade Team

    2016-05-01

    In order to test the peeling–ballooning ELM model, ECRH heating was applied to the edge of ASDEX Upgrade type-I ELMy H-mode plasmas to alter the pedestal pressure and current density profiles. The discharges were analysed with respect to ideal MHD stability. While the ELM frequency increased and the pedestal gradients relaxed with edge ECRH, the MHD stability boundary did not change. The results indicate that the peeling–ballooning model is insufficient to fully explain the triggering of ELM instabilities in the presence of edge ECRH heating.

  9. Fringe jump analysis and implementation of polarimetry on the ASDEX Upgrade DCN interferometer

    SciTech Connect

    Mlynek, A. Casali, L.; Eixenberger, H.; Ford, O.

    2014-11-15

    The ASDEX Upgrade tokamak is equipped with a 5-channel DCN interferometer with a probing wavelength of 195 μm. Up to now, phase measurement and density calculation have been accomplished by hard-wired phase counting electronics. Meanwhile, a fast digitizer has been installed which acquires the raw signals. That way, the various causes of counting errors by integer multiples of 2π, so-called fringe jumps, can be analyzed, and phase reconstruction schemes based on digital signal processing can be developed. In addition, a prototype polarimeter setup has been installed on one channel and allows for measurement of the Faraday rotation experienced by the probing beam.

  10. Influence of gas injection location and magnetic perturbations on ICRF antenna performance in ASDEX Upgrade

    SciTech Connect

    Bobkov, V.; Bilato, R.; Dux, R.; Faugel, H.; Kallenbach, A.; Müller, H. W.; Potzel, S.; Pütterich, Th.; Suttrop, W.; Stepanov, I.; Noterdaeme, J.-M.; Jacquet, P.; Monakhov, I.; Czarnecka, A.; Collaboration: ASDEX Upgrade Team

    2014-02-12

    In ASDEX Upgrade H-modes with H{sub 98}≈0.95, similar effect of the ICRF antenna loading improvement by local gas injection was observed as previously in L-modes. The antenna loading resistance R{sub a} between and during ELMs can increase by more than 25% after a switch-over from a deuterium rate of 7.5⋅10{sup 21} D/s injected from a toroidally remote location to the same amount of deuterium injected close to an antenna. However, in contrast to L-mode, this effect is small in H-mode when the valve downstream w.r.t. parallel plasma flows is used. In L-mode, a non-linearity of R{sub a} at P{sub ICRP}<30 kW is observed when using the gas valve integrated in antenna. Application of magnetic perturbations (MPs) in H-mode discharges leads to an increase of R{sub a}>30% with no effect of spectrum and phase of MPs on R{sub a} found so far. In the case ELMs are fully mitigated, the antenna loading is higher and steadier. In the case ELMs are not fully mitigated, the value of R{sub a} between ELMs is increased. Looking at the W source modification for the improved loading, the local gas injection is accompanied by decreased values of tungsten (W) influx Γ{sub W} from the limiters and its effective sputtering yield Y{sub w}, with the exception of the locations directly at the antenna gas valve. Application of MPs leads to increase of Γ{sub W} and Y{sub w} for some of the MP phases. With nitrogen seeding in the divertor, ICRF is routinely used to avoid impurity accumulation and that despite enhanced Γ{sub W} and Y{sub W} at the antenna limiters.

  11. Perturbative Thermal Transport Studies on Alcator C-Mod and ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Creely, A. J.; White, A. E.; Edlund, E. M.; Howard, N. T.; Hubbard, A. E.; Ryter, F.

    2015-11-01

    Perturbative thermal diffusivity has been measured on Alcator C-Mod and ASDEX Upgrade via the extended-time-to-peak method with heat pulses generated by partial sawtooth crashes. Heat pulses generated by sawtooth crashes have been used extensively in the past to study perturbative diffusivity, but the details of the sawtooth event lead to non-diffusive ``ballistic'' transport, invalidating their use for measuring perturbative diffusivity. Partial sawteeth generate a heat pulse without the ballistic transport of full sawteeth [Fredrickson 2000]. Partial sawtooth analysis was applied to over 50 C-Mod shots containing both L- and I-Mode, as well as ASDEX Upgrade plasmas, though partial sawteeth were less common on AUG. Results indicate correlations between perturbative diffusivity and confinement regime (L- vs. I-mode), as well as correlations with local temperature, density, the associated gradients, and gradient scale lengths (a/LTe and a/Ln). Finally, diffusivities calculated from partial sawteeth were compared to perturbative diffusivities calculated with the GYRO gyrokinetic code, leading to quantitative agreement with multi-scale GYRO simulations. This work is supported by the US DOE under grants DE-SC0006419 and DE-FC02-99ER54512-CMOD.

  12. Tungsten erosion in the baffle and outboard regions of the ITER-like ASDEX Upgrade divertor

    NASA Astrophysics Data System (ADS)

    Maier, H.; ASDEX Upgrade Team

    2004-12-01

    Similar to the design of the next-step device ITER, ASDEX Upgrade is equipped with vertical divertor targets with adjacent baffles extending towards the main chamber. In ITER, it is intended to employ tungsten as a plasma-facing material in this baffle area. Tungsten-coated graphite tiles were installed in the divertor baffle and the outboard side regions of ASDEX Upgrade for a full experimental campaign. The erosion behavior of tungsten was investigated by scanning electron microscopy and by measuring the thickness of the tungsten coatings before and after exposure. The coatings had an initial thickness of approximately 450 nm. Two distinct erosion mechanisms were observed: in the outer baffle region a reduction of the coatings' thickness up to 100 nm was determined after about 6300 s of plasma discharge. On the roof baffle and on the inner baffle modules, no clear reduction of the film thickness was found. In the tracks of arcs, however, the tungsten coatings were completely removed. This represents an erosion of 5-10% of the tungsten-coated surface area in this region.

  13. Commissioning activities and first results from the collective Thomson scattering diagnostic on ASDEX Upgrade (invited)

    SciTech Connect

    Meo, F.; Bindslev, H.; Korsholm, S. B.; Furtula, V.; Leipold, F.; Michelsen, P. K.; Nielsen, S. K.; Salewski, M.; Leuterer, F.; Woskov, P.; Stober, J.; Wagner, D.

    2008-10-15

    The collective Thomson scattering (CTS) diagnostic installed on ASDEX Upgrade uses millimeter waves generated by the newly installed 1 MW dual frequency gyrotron as probing radiation at 105 GHz. It measures backscattered radiation with a heterodyne receiver having 50 channels (between 100 and 110 GHz) to resolve the one-dimensional velocity distribution of the confined fast ions. The steerable antennas will allow different scattering geometries to fully explore the anisotropic fast ion distributions at different spatial locations. This paper covers the capabilities and operational limits of the diagnostic. It then describes the commissioning activities carried out to date. These activities include gyrotron studies, transmission line alignment, and beam pattern measurements in the vacuum vessel. Overlap experiments in near perpendicular and near parallel have confirmed the successful alignment of the system. First results in near perpendicular of scattered spectra in a neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH) plasma (minority hydrogen) on ASDEX Upgrade have shown evidence of ICRH heating phase of hydrogen.

  14. Commissioning activities and first results from the collective Thomson scattering diagnostic on ASDEX Upgrade (invited).

    PubMed

    Meo, F; Bindslev, H; Korsholm, S B; Furtula, V; Leuterer, F; Leipold, F; Michelsen, P K; Nielsen, S K; Salewski, M; Stober, J; Wagner, D; Woskov, P

    2008-10-01

    The collective Thomson scattering (CTS) diagnostic installed on ASDEX Upgrade uses millimeter waves generated by the newly installed 1 MW dual frequency gyrotron as probing radiation at 105 GHz. It measures backscattered radiation with a heterodyne receiver having 50 channels (between 100 and 110 GHz) to resolve the one-dimensional velocity distribution of the confined fast ions. The steerable antennas will allow different scattering geometries to fully explore the anisotropic fast ion distributions at different spatial locations. This paper covers the capabilities and operational limits of the diagnostic. It then describes the commissioning activities carried out to date. These activities include gyrotron studies, transmission line alignment, and beam pattern measurements in the vacuum vessel. Overlap experiments in near perpendicular and near parallel have confirmed the successful alignment of the system. First results in near perpendicular of scattered spectra in a neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH) plasma (minority hydrogen) on ASDEX Upgrade have shown evidence of ICRH heating phase of hydrogen. PMID:19044487

  15. Improved Collective Thomson Scattering measurements of fast ions at ASDEX upgrade

    SciTech Connect

    Rasmussen, J.; Nielsen, S. K.; Stejner, M.; Salewski, M.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Meo, F.; Michelsen, P. K.; Schubert, M.; Stober, J.; Tardini, G.; Wagner, D.; Collaboration: ASDEX Upgrade Team

    2014-08-21

    Understanding the behaviour of the confined fast ions is important in both current and future fusion experiments. These ions play a key role in heating the plasma and will be crucial for achieving conditions for burning plasma in next-step fusion devices. Microwave-based Collective Thomson Scattering (CTS) is well suited for reactor conditions and offers such an opportunity by providing measurements of the confined fast-ion distribution function resolved in space, time and 1D velocity space. We currently operate a CTS system at ASDEX Upgrade using a gyrotron which generates probing radiation at 105 GHz. A new setup using two independent receiver systems has enabled improved subtraction of the background signal, and hence the first accurate characterization of fast-ion properties. Here we review this new dual-receiver CTS setup and present results on fast-ion measurements based on the improved background characterization. These results have been obtained both with and without NBI heating, and with the measurement volume located close to the centre of the plasma. The measurements agree quantitatively with predictions of numerical simulations. Hence, CTS studies of fast-ion dynamics at ASDEX Upgrade are now feasible. The new background subtraction technique could be important for the design of CTS systems in other fusion experiments.

  16. Consistency between real and synthetic fast-ion measurements at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Rasmussen, J.; Nielsen, S. K.; Stejner, M.; Geiger, B.; Salewski, M.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Michelsen, P. K.; Moseev, D.; Schubert, M.; Stober, J.; Tardini, G.; Wagner, D.; The ASDEX Upgrade Team

    2015-07-01

    Internally consistent characterization of the properties of the fast-ion distribution from multiple diagnostics is a prerequisite for obtaining a full understanding of fast-ion behavior in tokamak plasmas. Here we benchmark several absolutely-calibrated core fast-ion diagnostics at ASDEX Upgrade by comparing fast-ion measurements from collective Thomson scattering, fast-ion {{\\text{D}}α} spectroscopy, and neutron rate detectors with numerical predictions from the TRANSP/NUBEAM transport code. We also study the sensitivity of the theoretical predictions to uncertainties in the plasma kinetic profiles. We find that theory and measurements generally agree within these uncertainties for all three diagnostics during heating phases with either one or two neutral beam injection sources. This suggests that the measurements can be described by the same model assuming classical slowing down of fast ions. Since the three diagnostics in the adopted configurations probe partially overlapping regions in fast-ion velocity space, this is also consistent with good internal agreement among the measurements themselves. Hence, our results support the feasibility of combining multiple diagnostics at ASDEX Upgrade to reconstruct the fast-ion distribution function in 2D velocity space.

  17. Recent improvements of the broadband FMCW reflectometry system for density profile measurements on ASDEX Upgrade

    SciTech Connect

    Silva, A.; Manso, M.; Varela, P.; Cupido, L.; Meneses, L.

    2006-10-15

    The broadband FMCW reflectometry system on ASDEX Upgrade has had significant improvements extending its measuring capabilities both on high and low density plasmas: (i) the upgrade of the W band to probe electron densities up to 12.4x10{sup 19} m{sup -3} with O mode (ii) Q and V frequency bands operating in X mode to probe the edge plasma and to provide information for O-mode profile initialization, and (iii) a new dynamic frequency calibration method to take into account all existing delays in the hyperabrupt varactor-tuned oscillator (HTO) tuning port and driver electronics. These improvements are particularly important to measure accurately the edge pedestal region of high density ITER relevant discharges. Density profiles obtained in high density discharges are presented and compared with results from both Li-beam and Thomson scattering diagnostics.

  18. Overview of recent pedestal studies at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Wolfrum, E.; Viezzer, E.; Burckhart, A.; Dunne, M. G.; Schneider, P. A.; Willensdorfer, M.; Fable, E.; Fischer, R.; Hatch, D.; Jenko, F.; Kurzan, B.; Manz, P.; Rathgeber, S. K.; the ASDEX Upgrade Team

    2015-05-01

    New or upgraded diagnostics of the edge transport barrier allow investigations of the dominant transport mechanisms in the pedestal. The density build-up after the L-H transition can be explained with a mainly diffusive edge transport barrier. A small inward convection term improves the agreement between modelling and experiment, but its existence cannot be confirmed due to the uncertainty in the neutral sources. Measurements of the impurity ion flow asymmetry as well as the edge current density are in agreement with neoclassical modelling. The inter-ELM pedestal recovery was traced with ideal peeling-ballooning modelling, which shows that the stability boundary moves closer to the operational point as the pedestal becomes wider. Gyrokinetic modelling of the different phases reveal that density gradient driven trapped electron modes are dominant during the early recovery, while electron temperature gradient modes or kinetic ballooning modes determine the temperature gradient in the final phase. Microtearing modes are modelled and also experimentally determined at the top of the pedestal. Non-linear coupling between modes could explain the failure of ideal linear MHD modelling.

  19. Investigations on Sawtooth Reconnection in ASDEX Upgrade Tokamak Discharges Using the 3D Non-linear Two-fluid MHD Code M3D-C1

    NASA Astrophysics Data System (ADS)

    Krebs, Isabel; Jardin, Stephen C.; Igochine, Valentin; Guenter, Sibylle; Hoelzl, Matthias; ASDEX Upgrade Team

    2014-10-01

    We study sawtooth reconnection in ASDEX Upgrade tokamak plasmas by means of 3D non-linear two-fluid MHD simulations in toroidal geometry using the high-order finite element code M3D-C1. Parameters and equilibrium of the simulations are based on typical sawtoothing ASDEX Upgrade discharges. The simulation results are compared to features of the experimental observations such as the sawtooth crash time and frequency, the evolution of the safety factor profile and the 3D evolution of the temperature. 2D ECE imaging measurements during sawtooth crashes in ASDEX Upgrade indicate that the heat is transported out of the core through a narrow poloidally localized region. We investigate if incomplete sawtooth reconnection can be seen in the simulations which is suggested by soft X-ray tomography measurements in ASDEX Upgrade showing that an (m = 1, n = 1) perturbation is typically observed to survive the sawtooth crash and approximately maintain its radial position.

  20. Electromagnetic effects on turbulent transport in high-performance ASDEX Upgrade discharges

    NASA Astrophysics Data System (ADS)

    Doerk, H.; Dunne, M.; Jenko, F.; Ryter, F.; Schneider, P. A.; Wolfrum, E.

    2015-04-01

    Modern tokamak H-mode discharges routinely operate at high plasma beta. Dedicated experiments performed on multiple machines measure contradicting dependence of the plasma confinement on this important parameter. In view of designing high-performance scenarios for next-generation devices like ITER, a fundamental understanding of the involved physics is crucial. Theoretical results—most of which have been obtained for simplified setups—indicate that increased beta does not only modify the characteristics of microturbulence but also potentially introduces fundamentally new physics. Empowered by highly accurate measurements at ASDEX Upgrade, the GENE turbulence code is used to perform a comprehensive gyrokinetic study of dedicated H-Mode plasmas. We find the stabilization of ion-temperature-gradient driven turbulence to be the most pronounced beta effect in these experimentally relevant cases. The resulting beta-improved core confinement should thus be considered for extrapolations to future machines.

  1. Electromagnetic simulations of the ASDEX Upgrade ICRF Antenna with the TOPICA code

    NASA Astrophysics Data System (ADS)

    Krivska, A.; Milanesio, D.; Bobkov, V.; Braun, F.; Noterdaeme, J.-M.

    2009-11-01

    Accurate and efficient simulation tools are necessary to optimize the ICRF antenna design for a set of operational conditions. The TOPICA code was developed for performance prediction and for the analysis of ICRF antenna systems in the presence of plasma, given realistic antenna geometries. Fully 3D antenna geometries can be adopted in TOPICA, just as in available commercial codes. But while those commercial codes cannot operate with a plasma loading, the TOPICA code correctly accounts for realistic plasma loading conditions, by means of the coupling with 1D FELICE code. This paper presents the evaluation of the electric current distribution on the structure, of the parallel electric field in the region between the straps and the plasma and the computation of sheaths driving RF potentials. Results of TOPICA simulations will help to optimize and re-design the ICRF ASDEX Upgrade antenna in order to reduce tungsten (W) sputtering attributed to the rectified sheath effect during ICRF operation.

  2. Density profile sensitivity study of ASDEX Upgrade ICRF Antennas with the TOPICA code

    NASA Astrophysics Data System (ADS)

    Krivska, A.; Ceccuzzi, S.; Milanesio, D.; Bobkov, V.; Braun, F.; Maggiora, R.; Noterdaeme, J.-M.; Tuccillo, A. A.

    2011-12-01

    During operation of the ASDEX Upgrade (AUG) ion cyclotron radio frequency (ICRF) system, Tungsten (W)-coated poloidal limiters and structures connected along magnetic field lines to the antenna can be sources of W, which is attributed to sputtering by ions accelerated in radio frequency (RF) sheaths. In order to analyze and optimize the ICRF antenna performance, accurate and efficient simulation tools are necessary. TOPICA code was developed for analysis of ICRF antenna systems with plasma loading conditions modeled with ID FELICE code. This paper presents an initial comparative analysis of two AUG ICRF antennas for a set of model plasma density profiles (with varying density gradient and antenna cut-off distance). The antennas are presently installed in AUG and differ in that one was partially optimized using HFSS code to reduce E∥ near fields. Power transferred to plasma and sheath driving RF potentials are computed.

  3. Studies of ICRF Discharge Conditioning (ICRF-DC) on ASDEX Upgrade, JET and TEXTOR

    SciTech Connect

    Lyssoivan, A.; Koch, R.; Eester, D. van; Wassenhove, G. van; Vervier, M.; Weynants, R.; Gauthier, E.; Bobkov, V.; Fahrbach, H.-U.; Hartmann, D.A.; Rohde, V.; Suttrop, W.; Noterdaeme, J.-M.; Monakhov, I.; Walden, A.

    2005-09-26

    The present paper reviews the recent results achieved in the ICRF-DC experiments performed in helium/hydrogen mixtures in the non-circular tokamaks ASDEX Upgrade and JET and first tests of the ICRF discharges in helium/oxygen mixtures in the circular tokamak TEXTOR. Special emphasis was given to study the physics of ICRF discharges. A new recipe for safe and reliable RF plasma production [{approx}(3-5)x1017 m-3, Te{approx}(3-5) eV] with improved antenna coupling efficiency (by 1.5-3 times) and improved radial/poloidal homogeneity was proposed and successfully tested: coupling the RF power in the FW-IBW mode conversion scenario in plasmas with two ion species. The first results on ICRF wall conditioning in helium/hydrogen and in helium/oxygen mixtures are analyzed.

  4. Resolving the bulk ion region of millimeter-wave collective Thomson scattering spectra at ASDEX Upgrade.

    PubMed

    Stejner, M; Nielsen, S; Jacobsen, A S; Korsholm, S B; Leipold, F; Meo, F; Michelsen, P K; Moseev, D; Rasmussen, J; Salewski, M; Schubert, M; Stober, J; Wagner, D H

    2014-09-01

    Collective Thomson scattering (CTS) measurements provide information about the composition and velocity distribution of confined ion populations in fusion plasmas. The bulk ion part of the CTS spectrum is dominated by scattering off fluctuations driven by the motion of thermalized ion populations. It thus contains information about the ion temperature, rotation velocity, and plasma composition. To resolve the bulk ion region and access this information, we installed a fast acquisition system capable of sampling rates up to 12.5 GS/s in the CTS system at ASDEX Upgrade. CTS spectra with frequency resolution in the range of 1 MHz are then obtained through direct digitization and Fourier analysis of the CTS signal. We here describe the design, calibration, and operation of the fast receiver system and give examples of measured bulk ion CTS spectra showing the effects of changing ion temperature, rotation velocity, and plasma composition. PMID:25273723

  5. Resolving the bulk ion region of millimeter-wave collective Thomson scattering spectra at ASDEX Upgrade

    SciTech Connect

    Stejner, M. Nielsen, S.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Meo, F.; Michelsen, P. K.; Rasmussen, J.; Salewski, M.; Moseev, D.; Schubert, M.; Stober, J.; Wagner, D. H.

    2014-09-15

    Collective Thomson scattering (CTS) measurements provide information about the composition and velocity distribution of confined ion populations in fusion plasmas. The bulk ion part of the CTS spectrum is dominated by scattering off fluctuations driven by the motion of thermalized ion populations. It thus contains information about the ion temperature, rotation velocity, and plasma composition. To resolve the bulk ion region and access this information, we installed a fast acquisition system capable of sampling rates up to 12.5 GS/s in the CTS system at ASDEX Upgrade. CTS spectra with frequency resolution in the range of 1 MHz are then obtained through direct digitization and Fourier analysis of the CTS signal. We here describe the design, calibration, and operation of the fast receiver system and give examples of measured bulk ion CTS spectra showing the effects of changing ion temperature, rotation velocity, and plasma composition.

  6. Turbulence intermittency linked to the weakly coherent mode in ASDEX Upgrade I-mode plasmas

    NASA Astrophysics Data System (ADS)

    Happel, T.; Manz, P.; Ryter, F.; Hennequin, P.; Hetzenecker, A.; Conway, G. D.; Guimarais, L.; Honoré, C.; Stroth, U.; Viezzer, E.; The ASDEX Upgrade Team

    2016-06-01

    This letter shows for the first time a pronounced increase of extremely intermittent edge density turbulence behavior inside the confinement region related to the I-mode confinement regime in the ASDEX Upgrade tokamak. With improving confinement, the perpendicular propagation velocity of density fluctuations in the plasma edge increases together with the intermittency of the observed density bursts. Furthermore, it is shown that the weakly coherent mode, a fluctuation feature generally observed in I-mode plasmas, is connected to the observed bursts. It is suggested that the large amplitude density bursts could be generated by a non-linearity similar to that in the Korteweg–de-Vries equation which includes the radial temperature gradient.

  7. Transport simulations of the pre-thermal-quench phase in ASDEX Upgrade massive gas injection experiments

    NASA Astrophysics Data System (ADS)

    Fable, E.; Pautasso, G.; Lehnen, M.; Dux, R.; Bernert, M.; Mlynek, A.; the ASDEX Upgrade Team

    2016-02-01

    The pre-thermal-quench (PTQ) phase of the massive gas injection (MGI) scenario to terminate the tokamak plasma discharge is studied by means of one-dimensional (1D) transport simulations. This phase is characterized by the cold-front penetration in the hot plasma after the gas has been released from the valves, and before the actual thermal quench takes place, with consequent plasma disruption at lower stored energy. The comparison between the simulations and the ASDEX Upgrade (AUG) experiments allows to gain insight in the observed dependencies and time scales. Despite the genuine three-dimensional structure of the problem, it is shown that the 1D simulations are already giving experimentally relevant answers, the reason for which will be discussed in detail. Influence of unknown parameters and simplifying assumptions are also discussed.

  8. Poloidal asymmetric flow and current relaxation of ballooned transport during I-phase in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Manz, P.; Birkenmeier, G.; Fuchert, G.; Cavedon, M.; Conway, G. D.; Maraschek, M.; Medvedeva, A.; Mink, F.; Scott, B. D.; Shao, L. M.; Stroth, U.

    2016-05-01

    Turbulence driven poloidal asymmetric parallel flow and current perturbations are studied for tokamak plasmas of circular geometry. Whereas zonal flows can lead to in-out asymmetry of parallel flows and currents via the Pfirsch-Schlüter mechanism, ballooned transport can result in an up-down asymmetry due to the Stringer spin-up mechanism. Measurements of up-down asymmetric parallel current fluctuations occurring during the I-phase in ASDEX Upgrade are not responses to the equilibrium by the Pfirsch-Schlüter current, but can be interpreted as a response to strongly ballooned plasma transport coupled with the Stringer spin-up mechanism. A good agreement of the experimental measured limit-cycle frequencies during I-phase with the Stringer spin-up relaxation frequency is found.

  9. Gyrokinetic studies of core turbulence features in ASDEX Upgrade H-mode plasmas

    SciTech Connect

    Navarro, A. Bañón Told, D.; Happel, T.; Görler, T.; Abiteboul, J.; Bustos, A.; Doerk, H.; Jenko, F.

    2015-04-15

    Gyrokinetic validation studies are crucial for developing confidence in the model incorporated in numerical simulations and thus improving their predictive capabilities. As one step in this direction, we simulate an ASDEX Upgrade discharge with the GENE code, and analyze various fluctuating quantities and compare them to experimental measurements. The approach taken is the following. First, linear simulations are performed in order to determine the turbulence regime. Second, the heat fluxes in nonlinear simulations are matched to experimental fluxes by varying the logarithmic ion temperature gradient within the expected experimental error bars. Finally, the dependence of various quantities with respect to the ion temperature gradient is analyzed in detail. It is found that density and temperature fluctuations can vary significantly with small changes in this parameter, thus making comparisons with experiments very sensitive to uncertainties in the experimental profiles. However, cross-phases are more robust, indicating that they are better observables for comparisons between gyrokinetic simulations and experimental measurements.

  10. Electromagnetic effects on turbulent transport in high-performance ASDEX Upgrade discharges

    SciTech Connect

    Doerk, H.; Dunne, M.; Ryter, F.; Schneider, P. A.; Wolfrum, E.; Jenko, F.

    2015-04-15

    Modern tokamak H-mode discharges routinely operate at high plasma beta. Dedicated experiments performed on multiple machines measure contradicting dependence of the plasma confinement on this important parameter. In view of designing high-performance scenarios for next-generation devices like ITER, a fundamental understanding of the involved physics is crucial. Theoretical results—most of which have been obtained for simplified setups—indicate that increased beta does not only modify the characteristics of microturbulence but also potentially introduces fundamentally new physics. Empowered by highly accurate measurements at ASDEX Upgrade, the GENE turbulence code is used to perform a comprehensive gyrokinetic study of dedicated H-Mode plasmas. We find the stabilization of ion-temperature-gradient driven turbulence to be the most pronounced beta effect in these experimentally relevant cases. The resulting beta-improved core confinement should thus be considered for extrapolations to future machines.

  11. Influence of rotation on the (m, n) = (3, 2) neoclassical tearing mode threshold in the ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Fietz, S.; Maraschek, M.; Zohm, H.; Reich, M.; Barrera, L.; McDermott, R. M.; the ASDEX Upgrade Team

    2013-08-01

    The influence of rotation on the (m, n) = (3, 2) neoclassical tearing mode onset and the marginal point at the ASDEX Upgrade is investigated. In this context, the different trigger mechanisms are identified and the influence of not only the rotation but also the rotation gradient and the differential rotation between the resonant and the triggering surface on the neoclassical tearing mode (NTM) stability is analysed. The existence of an upper NTM onset threshold can be observed in correlation with the rotation normalized to the Alfvén velocity. It can also clearly be verified that at the ASDEX Upgrade the NTM onset threshold increases with co- and counter-current directed rotation and also with positive and negative rotation gradient.

  12. Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Casson, F. J.; McDermott, R. M.; Angioni, C.; Camenen, Y.; Dux, R.; Fable, E.; Fischer, R.; Geiger, B.; Manas, P.; Menchero, L.; Tardini, G.; the ASDEX Upgrade Team

    2013-06-01

    Upgraded spectroscopic hardware and an improved impurity concentration calculation allow accurate determination of boron density in the ASDEX Upgrade tokamak. A database of boron measurements is compared to quasilinear and nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational effects over a range of H-mode plasma regimes. The peaking of the measured boron profiles shows a strong anti-correlation with the plasma rotation gradient, via a relationship explained and reproduced by the theory. It is demonstrated that the rotodiffusive impurity flux driven by the rotation gradient is required for the modelling to reproduce the hollow boron profiles at higher rotation gradients. The nonlinear simulations validate the quasilinear approach, and, with the addition of perpendicular flow shear, demonstrate that each symmetry breaking mechanism that causes momentum transport also couples to rotodiffusion. At lower rotation gradients, the parallel compressive convection is required to match the most peaked boron profiles. The sensitivities of both datasets to possible errors is investigated, and quantitative agreement is found within the estimated uncertainties. The approach used can be considered a template for mitigating uncertainty in quantitative comparisons between simulation and experiment.

  13. A detailed comparison of antenna impedance measurements on ASDEX Upgrade with the ion cyclotron range of frequencies antenna code TOPICA

    NASA Astrophysics Data System (ADS)

    Stepanov, I.; Noterdaeme, J.-M.; Bobkov, V.; Faugel, H.; Coster, D.; Milanesio, D.; Maggiora, R.; Siegl, G.; Bilato, R.; Brambilla, M.; Verdoolaege, G.; Braun, F.; Fünfgelder, H.; D'Inca, R.; Suttrop, W.; Kallenbach, A.; Schweinzer, J.; Wolfrum, E.; Fischer, R.; Mlynek, A.; Nikolaeva, V.; Guimarais, L.; the ASDEX Upgrade Team

    2015-09-01

    New antenna diagnostics on the ASDEX Upgrade, in the form of voltage and current probe pairs on the feeding lines of each ion cyclotron range of frequencies antenna, close to the input ports, have made it possible to study in detail the behavior of the ASDEX Upgrade two-strap antenna under changing loading conditions, and compare these measurements with the results of simulations using the TOPICA code. The present work extends previous studies by using the input impedance (more precisely, the complex voltage reflection coefficient Γ ) on each antenna port for comparison, instead of the more commonly used loading resistance or coupled power. The electron density profiles used for the simulation were reconstructed from the deuterium-carbon-nitrogen interferometer and lithium beam emission spectroscopy measurements, edge-localized mode-synchronized and averaged over time intervals from 10 to 200 ms depending on the case; 112 cases were compared from seven ASDEX Upgrade discharges with widely different plasma parameters and two operating frequencies (30 and 36.5 MHz). Very good agreement in \\vert Γ\\vert was found with the measurements on antenna 3 (<3% averaged over a shot), and good agreement was found with antennas 1 and 2 (<10%) the code reproduced the correct trend in loading resistance {{R}\\text{L}} in a significant majority of cases, although the discrepancies in the absolute values were rather high (up to  ˜50%) due to high reflection. Sources of discrepancy are discussed.

  14. Current fast ion collective Thomson scattering diagnostics at TEXTOR and ASDEX Upgrade, and ITER plans (invited)

    SciTech Connect

    Korsholm, S. B.; Bindslev, H.; Meo, F.; Leipold, F.; Michelsen, P. K.; Michelsen, S.; Nielsen, S. K.; Tsakadze, E. L.; Woskov, P.; Westerhof, E.; Oosterbeek, J. W.; Hoekzema, J.; Leuterer, F.; Wagner, D

    2006-10-15

    Fast ion physics will play an important role on ITER where confined alpha particles will affect plasma dynamics and overall confinement. Fast ion collective Thomson scattering (CTS) using gyrotrons has the potential to meet the need for measuring the spatially localized velocity distributions of confined fast ions in ITER. Currently, CTS experiments are performed at TEXTOR using a 150 kW, 0.2 s, 110 GHz gyrotron and a receiver upgraded at the Risoe National Laboratory. The gyrotron and receiver optics have also been upgraded for rapid scanning during a plasma shot. The receiver consists of a nine-mirror quasioptical transmission line including a universal polarizer and a 42-channel data acquisition system, which allows complete coverage of the double sideband scattered spectrum for localized ({approx}10 cm) time resolved (4 ms) measurements of the ion velocity distribution. At ASDEX Upgrade (AUG) a similar 50-channel CTS receiver has been installed. This CTS system will use the 105 GHz frequency of a dual frequency gyrotron. The gyrotron is presently being commissioned. CTS campaigns are scheduled for the summer of 2006 with a probe power of up to 1 MW for 10 s. This report presents the alignment of the quasioptical transmission line, calibration, and gyrotron tuning of the TEXTOR and AUG CTS systems. We will also review the progress on the design of the proposed fast ion CTS diagnostic for ITER. It is envisaged that scattered radiation from two 60 GHz probe beams launched from the low field side midplane port will be received by two arrays of receivers located on the low and high field sides of the plasma. This geometry will allow the ion velocity distribution near perpendicular and near parallel to the magnetic field to be measured in ten or more spatial locations covering the full plasma cross section. The temporal resolution can be significantly better than the required 100 ms.

  15. Migration and deposition of 13C in the full-tungsten ASDEX Upgrade tokamak

    NASA Astrophysics Data System (ADS)

    Hakola, A.; Likonen, J.; Aho-Mantila, L.; Groth, M.; Koivuranta, S.; Krieger, K.; Kurki-Suonio, T.; Makkonen, T.; Mayer, M.; Müller, H. W.; Neu, R.; Rohde, V.; ASDEX Upgrade Team

    2010-06-01

    The migration of carbon in low-density, low-confinement plasmas of ASDEX Upgrade was studied by injecting 13C into the main chamber of the torus at the end of the 2007 experimental campaign. A selection of standard tungsten-coated lower-divertor and main-chamber tiles as well as a complete set of lower-divertor tiles with an uncoated poloidal marker stripe were removed from one poloidal cross section and analysed using secondary ion mass spectrometry. The poloidal deposition profiles of 13C on both the tungsten-coated tiles and on the uncoated graphite areas of the marker tiles were measured and compared. For the W-coated lower-divertor tiles, 13C was deposited mainly on the high-field side tiles, while barely detectable amounts of 13C were observed on low-field side samples. In contrast, on the uncoated marker stripes the deposition was equally pronounced in the high-field and low-field side divertor. The marker-tile results are in agreement with those obtained from graphite tiles after the 2003 and 2005 13C experiments in ASDEX Upgrade. In the case of W-coated tiles, the 13C measurements were complemented by determining the total amount of deposited carbon (12C) on the tiles, which also shows strong deposition at the inner parts of the lower divertor. The estimated deposition of 13C on W at the divertor areas was less than 1.5% of the injected amount of 13C atoms. The 13C analyses of the main-chamber tiles and small silicon samples mounted in remote areas revealed significant deposition in the upper divertor, in upper parts of the heat shield, in the limiter region close to the injection valve, and below the roof baffle. Approximately 8% of the injected 13C is estimated to have accumulated in these regions. Possible reasons for the different deposition patterns on W and on graphite in different regions of the torus are discussed.

  16. Comparisons between global and local gyrokinetic simulations of an ASDEX Upgrade H-mode plasma

    NASA Astrophysics Data System (ADS)

    Navarro, Alejandro Bañón; Told, Daniel; Jenko, Frank; Görler, Tobias; Happel, Tim

    2016-04-01

    We investigate by means of local and global nonlinear gyrokinetic GENE simulations an ASDEX Upgrade H-mode plasma. We find that for the outer core positions (i.e., ρ tor ≈ 0.5 - 0.7 ), nonlocal effects are important. For nominal input parameters local simulations over-predict the experimental heat fluxes by a large factor, while a good agreement is found with global simulations. This was a priori not expected, since the values of 1 / ρ ⋆ were large enough that global and local simulations should have been in accordance. Nevertheless, due to the high sensitivity of the heat fluxes with respect to the input parameters, it is still possible to match the heat fluxes in local simulations with the experimental and global results by varying the ion temperature gradient within the experimental uncertainties. In addition to that, once an agreement in the transport quantities between local (flux-matched) and global simulations is achieved, an agreement for other quantities, such as density and temperature fluctuations, is also found. The case presented here clearly shows that even in the presence of global size-effects, the local simulation approach is still a valid and accurate approach.

  17. Adjoint Monte Carlo simulation of fusion product activation probe experiment in ASDEX Upgrade tokamak

    NASA Astrophysics Data System (ADS)

    Äkäslompolo, S.; Bonheure, G.; Tardini, G.; Kurki-Suonio, T.; The ASDEX Upgrade Team

    2015-10-01

    The activation probe is a robust tool to measure flux of fusion products from a magnetically confined plasma. A carefully chosen solid sample is exposed to the flux, and the impinging ions transmute the material making it radioactive. Ultra-low level gamma-ray spectroscopy is used post mortem to measure the activity and, thus, the number of fusion products. This contribution presents the numerical analysis of the first measurement in the ASDEX Upgrade tokamak, which was also the first experiment to measure a single discharge. The ASCOT suite of codes was used to perform adjoint/reverse Monte Carlo calculations of the fusion products. The analysis facilitates, for the first time, a comparison of numerical and experimental values for absolutely calibrated flux. The results agree to within a factor of about two, which can be considered a quite good result considering the fact that all features of the plasma cannot be accounted in the simulations.Also an alternative to the present probe orientation was studied. The results suggest that a better optimized orientation could measure the flux from a significantly larger part of the plasma. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  18. Global electromagnetic simulations of the outer core of an ASDEX Upgrade L-mode plasma

    NASA Astrophysics Data System (ADS)

    Abiteboul, J.; Görler, T.; Jenko, F.; Told, D.

    2015-09-01

    The outer core of a low confinement discharge performed at the ASDEX Upgrade tokamak is investigated using both global and local nonlinear gyrokinetic simulations. Previous work [Told et al., Phys. Plasmas 20, 122312 (2013)] had shown that local gyrokinetic simulations agree reasonably well with experimental results in terms of transport levels, with minor discrepancies that can be resolved within the uncertainties of the experimental profile. In the present work, the analysis of the same discharge is extended to include global gradient-driven simulations with the GENE code, taking into account the plasma profiles from mid-radius up to close to the separatrix. It is shown that the mean fluxes obtained assuming the local approximation are in general agreement with results from global simulations. Moreover, both types of simulations exhibit large-scale avalanche-like events, both in the ion and electron heat fluxes, with similar basic properties. However, analyzing the statistics of the fluxes reveals that intermittency is more important in the global case. Furthermore, even when averaging over turbulent time scales, radial corrugations in the ion temperature profile are identified in the global simulation. These corrugations are at most of the order of 1%, but correspond to up to 10% variations in the gradient. Thus, while the results on the mean fluxes support the validity of the local approximation, the presence of corrugated structures may pose a challenge for the direct validation of local gyrokinetic simulations against experiments.

  19. Estimation of sheath potentials in front of ASDEX upgrade ICRF antenna with SSWICH asymptotic code

    NASA Astrophysics Data System (ADS)

    Křivská, A.; Bobkov, V.; Colas, L.; Jacquot, J.; Milanesio, D.; Ochoukov, R.

    2015-12-01

    Multi-megawatt Ion Cyclotron Range of Frequencies (ICRF) heating became problematic in ASDEX Upgrade (AUG) tokamak after coating of ICRF antenna limiters and other plasma facing components by tungsten. Strong impurity influx was indeed produced at levels of injected power markedly lower than in the previous experiments. It is assumed that the impurity production is mainly driven by parallel component of Radio-Frequency (RF) antenna electric near-field E// that is rectified in sheaths. In this contribution we estimate poloidal distribution of sheath Direct Current (DC) potential in front of the ICRF antenna and simulate its relative variations over the parametric scans performed during experiments, trying to reproduce some of the experimental observations. In addition, relative comparison between two types of AUG ICRF antenna configurations, used for experiments in 2014, has been performed. For this purpose we use the Torino Polytechnic Ion Cyclotron Antenna (TOPICA) code and asymptotic version of the Self-consistent Sheaths and Waves for Ion Cyclotron Heating (SSWICH) code. Further, we investigate correlation between amplitudes of the calculated oscillating sheath voltages and the E// fields computed at the lateral side of the antenna box, in relation with a heuristic antenna design strategy at IPP Garching to mitigate RF sheaths.

  20. Simulation and real-time estimation of sawtooth crash effects on ASDEX-Upgrade plasmas

    NASA Astrophysics Data System (ADS)

    Piron, Chiara; Felici, Federico; Kim, Doohyun; Piovesan, Paolo; Rapson, Chris; Reich, Matthias; Sauter, Olivier; Treutterer, Wolfgang; van den Brand, Hugo; ASDEX Upgrade Team

    2014-10-01

    This work presents the integration of Porcelli's sawtooth model, including partial and full reconnection triggered by a shear threshold, in the RAPid Transport simulatOR code (RAPTOR) and its application to ASDEX-Upgrade(AUG) experiments. RAPTOR is a 1D profile evolution code designed for real-time reconstruction and control applications. RAPTOR is used in predictive simulations to model the plasma profile in sawtoothing AUG discharges, but it also simulates the profile evolution in real-time, yielding a plasma state estimate that includes the effect of sawteeth. This work aims to model AUG scenarios with sawteeth and to understand sawtooth control and locking experiments. It also discusses the improvements in the plasma state reconstruction, in particular in the evolution of the q-profile, obtained by the inclusion of Porcelli's model in the code. Possible applications to real-time sawtooth control, like suitable power actuator schemes and locking techniques, are investigated as well. This project has received funding from the EURATOM research and training programme 2014--2018.

  1. Gyrokinetic studies of core turbulence features in ASDEX Upgrade: Can gyrokinetic simulations match the fluctuation measurements?

    NASA Astrophysics Data System (ADS)

    Banon Navarro, Alejandro

    2015-11-01

    Worldwide, gyrokinetic codes are used to predict the dominant micro-instabilities as well as the resulting anomalous transport in fusion experiments. A careful verification and validation of these codes is crucial to develop confidence in the model and improving the predictive capabilities of the numerical simulations. To date, the validation of gyrokinetic simulations versus experiments is mainly done at a macroscopic level, namely, by comparing turbulent heat fluxes. This is usually achieved by varying the profile gradients within the experimental error bars until a match with the experimental heat fluxes is obtained. However, since the turbulent fluxes are caused by plasma fluctuations on microscopic scales, it is also necessary to validate gyrokinetic codes on a microscopic level. We will describe a recent step in this direction by presenting simulation results with the gyrokinetic code GENE for an ASDEX Upgrade discharge. In particular, after flux-matched simulations are achieved, density fluctuations measured by means of Doppler reflectometry are compared with results of gyrokinetic simulations. We will also show that density and temperature fluctuation amplitudes and even the fluctuation spectra can be very sensitive to small changes in the profile gradients. This implies that a match of gyrokinetic simulations with experiment measurements for these quantities can be very difficult to achieve. However, it is observed that cross-phases between different quantities are robust to changes in this parameter, indicating that cross-phases could be a better observable for comparisons with experimental measurements.

  2. Non-monotonic growth rates of sawtooth precursors evidenced with a new method on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Vezinet, D.; Igochine, V.; Weiland, M.; Yu, Q.; Gude, A.; Meshcheriakov, D.; Sertoli, M.; the Asdex Upgrade Team; the EUROfusion MST1 Team

    2016-08-01

    This paper describes a new method to derive, from soft x-ray (SXR) tomography, robust estimates of the core displacement, growth rate and frequency of a 1/1 sawtooth crash precursor. The method is valid for very peaked SXR profiles and is robust against both the inversion algorithm and the presence of tungsten in a rotating plasma. Three typical ASDEX Upgrade crashes are then analysed. In all cases a postcursor is observed, suggesting incomplete reconnection. Despite different dynamics, in all three cases the growth rate of the core displacement shows similar features. First, it is not constant, supporting the idea of non-linear growth. Second, it can be divided into clearly identified phases with quasi-constant growth rates, suggesting sudden change of growth regime rather than smooth transitions. Third, its evolution is non-monotonic, with phases of accelerated growth followed by damped phases. This damping is interpreted for two cases respectively as an effect of fast ions and of mode coupling, based on the result of a MHD simulation. The mode frequency is observed in all cases to be closely related to the plasma bulk rotation profile, with little or no visible effect of the electron diamagnetic drift frequency. The onset criterion could not be clearly identified and it is shown that the role of the pressure gradient is not as expected from a naive extrapolation of the linear stability theory.

  3. Improved time-frequency analysis of ASDEX Upgrade reflectometry data using the reassigned spectrogram technique.

    PubMed

    Varela, P; Silva, A; da Silva, F; da Graça, S; Manso, M E; Conway, G D

    2010-10-01

    The spectrogram is one of the best-known time-frequency distributions suitable to analyze signals whose energy varies both in time and frequency. In reflectometry, it has been used to obtain the frequency content of FM-CW signals for density profile inversion and also to study plasma density fluctuations from swept and fixed frequency data. Being implemented via the short-time Fourier transform, the spectrogram is limited in resolution, and for that reason several methods have been developed to overcome this problem. Among those, we focus on the reassigned spectrogram technique that is both easily automated and computationally efficient requiring only the calculation of two additional spectrograms. In each time-frequency window, the technique reallocates the spectrogram coordinates to the region that most contributes to the signal energy. The application to ASDEX Upgrade reflectometry data results in better energy concentration and improved localization of the spectral content of the reflected signals. When combined with the automatic (data driven) window length spectrogram, this technique provides improved profile accuracy, in particular, in regions where frequency content varies most rapidly such as the edge pedestal shoulder. PMID:21061480

  4. A new compact solid-state neutral particle analyser at ASDEX Upgrade: Setup and physics modeling

    SciTech Connect

    Schneider, P. A.; Blank, H.; Geiger, B.; Mank, K.; Martinov, S.; Ryter, F.; Weiland, M.; Weller, A.

    2015-07-15

    At ASDEX Upgrade (AUG), a new compact solid-state detector has been installed to measure the energy spectrum of fast neutrals based on the principle described by Shinohara et al. [Rev. Sci. Instrum. 75, 3640 (2004)]. The diagnostic relies on the usual charge exchange of supra-thermal fast-ions with neutrals in the plasma. Therefore, the measured energy spectra directly correspond to those of confined fast-ions with a pitch angle defined by the line of sight of the detector. Experiments in AUG showed the good signal to noise characteristics of the detector. It is energy calibrated and can measure energies of 40-200 keV with count rates of up to 140 kcps. The detector has an active view on one of the heating beams. The heating beam increases the neutral density locally; thereby, information about the central fast-ion velocity distribution is obtained. The measured fluxes are modeled with a newly developed module for the 3D Monte Carlo code F90FIDASIM [Geiger et al., Plasma Phys. Controlled Fusion 53, 65010 (2011)]. The modeling allows to distinguish between the active (beam) and passive contributions to the signal. Thereby, the birth profile of the measured fast neutrals can be reconstructed. This model reproduces the measured energy spectra with good accuracy when the passive contribution is taken into account.

  5. A new compact solid-state neutral particle analyser at ASDEX Upgrade: Setup and physics modeling

    NASA Astrophysics Data System (ADS)

    Schneider, P. A.; Blank, H.; Geiger, B.; Mank, K.; Martinov, S.; Ryter, F.; Weiland, M.; Weller, A.

    2015-07-01

    At ASDEX Upgrade (AUG), a new compact solid-state detector has been installed to measure the energy spectrum of fast neutrals based on the principle described by Shinohara et al. [Rev. Sci. Instrum. 75, 3640 (2004)]. The diagnostic relies on the usual charge exchange of supra-thermal fast-ions with neutrals in the plasma. Therefore, the measured energy spectra directly correspond to those of confined fast-ions with a pitch angle defined by the line of sight of the detector. Experiments in AUG showed the good signal to noise characteristics of the detector. It is energy calibrated and can measure energies of 40-200 keV with count rates of up to 140 kcps. The detector has an active view on one of the heating beams. The heating beam increases the neutral density locally; thereby, information about the central fast-ion velocity distribution is obtained. The measured fluxes are modeled with a newly developed module for the 3D Monte Carlo code F90FIDASIM [Geiger et al., Plasma Phys. Controlled Fusion 53, 65010 (2011)]. The modeling allows to distinguish between the active (beam) and passive contributions to the signal. Thereby, the birth profile of the measured fast neutrals can be reconstructed. This model reproduces the measured energy spectra with good accuracy when the passive contribution is taken into account.

  6. Investigation of scrape-off layer and divertor heat transport in ASDEX Upgrade L-mode

    NASA Astrophysics Data System (ADS)

    Sieglin, B.; Eich, T.; Faitsch, M.; Herrmann, A.; Scarabosio, A.; the ASDEX Upgrade Team

    2016-05-01

    Power exhaust is one of the major challenges for the development of a fusion power plant. Predictions based upon a multimachine database give a scrape-off layer power fall-off length {λq}≤slant 1 mm for large fusion devices such as ITER. The power deposition profile on the target is broadened in the divertor by heat transport perpendicular to the magnetic field lines. This profile broadening is described by the power spreading S. Hence both {λq} and S need to be understood in order to estimate the expected divertor heat load for future fusion devices. For the investigation of S and {λq} L-Mode discharges with stable divertor conditions in hydrogen and deuterium were conducted in ASDEX Upgrade. A strong dependence of S on the divertor electron temperature and density is found which is the result of the competition between parallel electron heat conductivity and perpendicular diffusion in the divertor region. For high divertor temperatures it is found that the ion gyro radius at the divertor target needs to be considered. The dependence of the in/out asymmetry of the divertor power load on the electron density is investigated. The influence of the main ion species on the asymmetric behaviour is shown for hydrogen, deuterium and helium. A possible explanation for the observed asymmetry behaviour based on vertical drifts is proposed.

  7. Multi-view fast-ion D-alpha spectroscopy diagnostic at ASDEX Upgrade

    SciTech Connect

    Geiger, B.; Dux, R.; McDermott, R. M.; Potzel, S.; Reich, M.; Ryter, F.; Weiland, M.; Wünderlich, D.; Garcia-Munoz, M.; Collaboration: ASDEX Upgrade Team

    2013-11-15

    A novel fast-ion D-alpha (FIDA) diagnostic that is based on charge exchange spectroscopy has been installed at ASDEX Upgrade. The diagnostic uses a newly developed high-photon-throughput spectrometer together with a low-noise EM-CCD camera that allow measurements with 2 ms exposure time. Absolute intensities are obtained by calibrating the system with an integrating sphere and the wavelength dependence is determined to high accuracy using a neon lamp. Additional perturbative contributions to the spectra, such as D{sub 2}-molecular lines, the Stark broadened edge D-alpha emission, and passive FIDA radiation have been identified and can be subtracted or avoided experimentally. The FIDA radiation from fast deuterium ions after charge exchange reactions can therefore be analyzed continuously without superimposed line emissions at large Doppler shifts. Radial information on the fast ions is obtained from radially distributed lines of sight. The investigation of the fast-ion velocity distribution is possible due to three different viewing geometries. The independent viewing geometries access distinct parts of the fast-ion velocity space and make tomographic reconstructions possible.

  8. Overview of ASDEX Upgrade results—development of integrated operating scenarios for ITER

    NASA Astrophysics Data System (ADS)

    Günter, S.; Angioni, C.; Apostoliceanu, M.; Atanasiu, C.; Balden, M.; Becker, G.; Becker, W.; Behler, K.; Behringer, K.; Bergmann, A.; Bilato, R.; Bizyukov, I.; Bobkov, V.; Bolzonella, T.; Borba, D.; Borrass, K.; Brambilla, M.; Braun, F.; Buhler, A.; Carlson, A.; Chankin, A.; Chen, J.; Chen, Y.; Cirant, S.; Conway, G.; Coster, D.; Dannert, T.; Dimova, K.; Drube, R.; Dux, R.; Eich, T.; Engelhardt, K.; Fahrbach, H.-U.; Fantz, U.; Fattorini, L.; Foley, M.; Franzen, P.; Fuchs, J. C.; Gafert, J.; Gal, K.; Gantenbein, G.; García Muñoz, M.; Gehre, O.; Geier, A.; Giannone, L.; Gruber, O.; Haas, G.; Hartmann, D.; Heger, B.; Heinemann, B.; Herrmann, A.; Hobirk, J.; Hohenöcker, H.; Horton, L.; Huart, M.; Igochine, V.; Jacchia, A.; Jakobi, M.; Jenko, F.; Kallenbach, A.; Kálvin, S.; Kardaun, O.; Kaufmann, M.; Keller, A.; Kendl, A.; Kick, M.; Kim, J.-W.; Kirov, K.; Klose, S.; Kochergov, R.; Kocsis, G.; Kollotzek, H.; Konz, C.; Kraus, W.; Krieger, K.; Kurki-Suonio, T.; Kurzan, B.; Lackner, K.; Lang, P. T.; Lauber, P.; Laux, M.; Leuterer, F.; Likonen, J.; Lohs, A.; Lorenz, A.; Lorenzini, R.; Lyssoivan, A.; Maggi, C.; Maier, H.; Mank, K.; Manini, A.; Manso, M.-E.; Mantica, P.; Maraschek, M.; Martin, P.; Mast, K. F.; Mayer, M.; McCarthy, P.; Meyer, H.; Meisel, D.; Meister, H.; Menmuir, S.; Meo, F.; Merkel, P.; Merkel, R.; Merkl, D.; Mertens, V.; Monaco, F.; Mück, A.; Müller, H. W.; Münich, M.; Murmann, H.; Na, Y.-S.; Narayanan, R.; Neu, G.; Neu, R.; Neuhauser, J.; Nishijima, D.; Nishimura, Y.; Noterdaeme, J.-M.; Nunes, I.; Pacco-Düchs, M.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pinches, S.; Poli, E.; Posthumus-Wolfrum, E.; Pütterich, T.; Pugno, R.; Quigley, E.; Radivojevic, I.; Raupp, G.; Reich, M.; Riedl, R.; Ribeiro, T.; Rohde, V.; Roth, J.; Ryter, F.; Saarelma, S.; Sandmann, W.; Santos, J.; Schall, G.; Schilling, H.-B.; Schirmer, J.; Schneider, W.; Schramm, G.; Schweinzer, J.; Schweizer, S.; Scott, B.; Seidel, U.; Serra, F.; Sihler, C.; Silva, A.; Sips, A.; Speth, E.; Stäbler, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Strintzi, D.; Strumberger, E.; Suttrop, W.; Tardini, G.; Tichmann, C.; Treutterer, W.; Troppmann, M.; Tsalas, M.; Urano, H.; Varela, P.; Wagner, D.; Wesner, F.; Würsching, E.; Ye, M. Y.; Yoon, S.-W.; Yu, Q.; Zaniol, B.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.; Zilker, M.; Zohm, H.

    2005-10-01

    Significant progress has been made on ASDEX Upgrade during the last two years in the basic understanding of transport, in the extension of the improved H-mode in parameter space and towards an integrated operating scenario and in the development of control methods for major performance limiting instabilities. The important features were the understanding of particle transport and the control of impurity accumulation based on it, the satisfactory operation with predominantly tungsten-clad walls, the improved H-mode operation over density ranges and for temperature ratios covering (non-simultaneously) the ITER requirements on ν*, n/nGW and Te/Ti, the ELM frequency control by pellet injection and the optimization of NTM suppression by DC-ECCD through variation of the launching angle. From these experiments an integrated scenario has emerged which extrapolates to a 50% improvement in n T τ or a 30% reduction of the required current when compared with the ITER base-line assumptions, with moderately peaked electron and controllable high-Z density profiles.

  9. Deuterium depth profile quantification in a ASDEX Upgrade divertor tile using secondary ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ghezzi, F.; Caniello, R.; Giubertoni, D.; Bersani, M.; Hakola, A.; Mayer, M.; Rohde, V.; Anderle, M.

    2014-10-01

    We present the results of a study where secondary ion mass spectrometry (SIMS) has been used to obtain depth profiles of deuterium concentration on plasma facing components of the first wall of the ASDEX Upgrade tokamak. The method uses primary and secondary standards to quantify the amount of deuterium retained. Samples of bulk graphite coated with tungsten or tantalum-doped tungsten are independently profiled with three different SIMS instruments. Their deuterium concentration profiles are compared showing good agreement. In order to assess the validity of the method, the integrated deuterium concentrations in the coatings given by one of the SIMS devices is compared with nuclear reaction analysis (NRA) data. Although in the case of tungsten the agreement between NRA and SIMS is satisfactory, for tantalum-doped tungsten samples the discrepancy is significant because of matrix effect induced by tantalum and differently eroded surface (W + Ta always exposed to plasma, W largely shadowed). A further comparison where the SIMS deuterium concentration is obtained by calibrating the measurements against NRA values is also presented. For the tungsten samples, where no Ta induced matrix effects are present, the two methods are almost equivalent.The results presented show the potential of the method provided that the standards used for the calibration reproduce faithfully the matrix nature of the samples.

  10. Design and performance of the collective Thomson scattering receiver at ASDEX Upgrade.

    PubMed

    Furtula, V; Salewski, M; Leipold, F; Michelsen, P K; Korsholm, S B; Meo, F; Moseev, D; Nielsen, S K; Stejner, M; Johansen, T

    2012-01-01

    Here we present the design of the fast-ion collective Thomson scattering receiver for millimeter wave radiation installed at ASDEX Upgrade, a tokamak for fusion plasma experiments. The receiver can detect spectral power densities of a few eV against the electron cyclotron emission background on the order of 100 eV under presence of gyrotron stray radiation that is several orders of magnitude stronger than the signal to be detected. The receiver down converts the frequencies of scattered radiation (100-110 GHz) to intermediate frequencies (IF) (4.5-14.5 GHz) by heterodyning. The IF signal is divided into 50 IF channels tightly spaced in frequency space. The channels are terminated by square-law detector diodes that convert the signal power into DC voltages. We present measurements of the transmission characteristics and performance of the main receiver components operating at mm-wave frequencies (notch, bandpass, and lowpass filters, a voltage-controlled variable attenuator, and an isolator), the down-converter unit, and the IF components (amplifiers, bandpass filters, and detector diodes). Furthermore, we determine the performance of the receiver as a unit through spectral response measurements and find reasonable agreement with the expectation based on the individual component measurements. PMID:22299951

  11. Frequency measurements of the gyrotrons used for collective Thomson scattering diagnostics at TEXTOR and ASDEX Upgrade

    SciTech Connect

    Woskov, P.; Bindslev, H.; Leipold, F.; Meo, F.; Nielsen, S. K.; Tsakadze, E. L.; Korsholm, S. B.; Scholten, J.; Tito, C.; Westerhof, E.; Oosterbeek, J. W.; Leuterer, F.; Monaco, F.; Muenich, M.; Wagner, D.

    2006-10-15

    High resolution frequency measurements of the 110 GHz gyrotron at TEXTOR and the 105 GHz mode of the two-frequency gyrotron (Odissey-1) at ASDEX Upgrade (AUG) have been made in support of fast ion collective Thomson scattering diagnostics. Measurements were done by harmonic heterodyne methods using both fast Fourier transform spectroscopy with digital oscilloscopes and fast scanning spectrum analyzers. Accurate frequencies were obtained with a frequency counter. At TEXTOR, at 180 kW forward power the starting frequency was 109.970{+-}0.005 GHz and chirped down as much as 27 MHz depending on the duty factor. At AUG, at 500 kW forward power the frequency started at 104.786 GHz and chirped down 104 MHz, with 90% of the chirp occurring in the first 100 ms. Plasma perturbation of the TEXTOR gyrotron was observed when both ion cyclotron resonance heating antennas and neutral beam injection were operating, producing modulation at 29 and 58 MHz in the gyrotron output. Each gyrotron was observed to have an instrumental measurement limited linewidth of 120 kHz full width at half maximum.

  12. Design and performance of the collective Thomson scattering receiver at ASDEX Upgrade

    SciTech Connect

    Furtula, V.; Salewski, M.; Leipold, F.; Michelsen, P. K.; Korsholm, S. B.; Meo, F.; Moseev, D.; Nielsen, S. K.; Stejner, M.; Johansen, T.

    2012-01-15

    Here we present the design of the fast-ion collective Thomson scattering receiver for millimeter wave radiation installed at ASDEX Upgrade, a tokamak for fusion plasma experiments. The receiver can detect spectral power densities of a few eV against the electron cyclotron emission background on the order of 100 eV under presence of gyrotron stray radiation that is several orders of magnitude stronger than the signal to be detected. The receiver down converts the frequencies of scattered radiation (100-110 GHz) to intermediate frequencies (IF) (4.5-14.5 GHz) by heterodyning. The IF signal is divided into 50 IF channels tightly spaced in frequency space. The channels are terminated by square-law detector diodes that convert the signal power into DC voltages. We present measurements of the transmission characteristics and performance of the main receiver components operating at mm-wave frequencies (notch, bandpass, and lowpass filters, a voltage-controlled variable attenuator, and an isolator), the down-converter unit, and the IF components (amplifiers, bandpass filters, and detector diodes). Furthermore, we determine the performance of the receiver as a unit through spectral response measurements and find reasonable agreement with the expectation based on the individual component measurements.

  13. Transport analysis of high radiation and high density plasmas in the ASDEX Upgrade tokamak

    NASA Astrophysics Data System (ADS)

    Casali, L.; Bernert, M.; Dux, R.; Fischer, R.; Kallenbach, A.; Kurzan, B.; Lang, P.; Mlynek, A.; McDermott, R. M.; Ryter, F.; Sertoli, M.; Tardini, G.; Zohm, H.

    2014-12-01

    Future fusion reactors, foreseen in the "European road map" such as DEMO, will operate under more demanding conditions compared to present devices. They will require high divertor and core radiation by impurity seeding to reduce heat loads on divertor target plates. In addition, DEMO will have to work at high core densities to reach adequate fusion performance. The performance of fusion reactors depends on three essential parameters: temperature, density and energy confinement time. The latter characterizes the loss rate due to both radiation and transport processes. The DEMO foreseen scenarios described above were not investigated so far, but are now addressed at the ASDEX Upgrade tokamak. In this work we present the transport analysis of such scenarios. Plasma with high radiation by impurity seeding: transport analysis taking into account the radiation distribution shows no change in transport during impurity seeding. The observed confinement improvement is an effect of higher pedestal temperatures which extend to the core via stiffness. A non coronal radiation model was developed and compared to the bolometric measurements in order to provide a reliable radiation profile for transport calculations. High density plasmas with pellets: the analysis of kinetic profiles reveals a transient phase at the start of the pellet fuelling due to a slower density build up compared to the temperature decrease. The low particle diffusion can explain the confinement behaviour.

  14. Gyrokinetic study of ASDEX Upgrade inter-ELM pedestal profile evolution

    NASA Astrophysics Data System (ADS)

    Hatch, D. R.; Told, D.; Jenko, F.; Doerk, H.; Dunne, M. G.; Wolfrum, E.; Viezzer, E.; The ASDEX Upgrade Team; Pueschel, M. J.

    2015-06-01

    The gyrokinetic GENE code is used to study the inter-ELM H-mode pedestal profile evolution for an ASDEX Upgrade discharge. Density gradient driven trapped electron modes are the dominant pedestal instability during the early density-buildup phase. Nonlinear simulations produce particle transport levels consistent with experimental expectations. Later inter-ELM phases appear to be simultaneously constrained by electron temperature gradient (ETG) and kinetic ballooning mode (KBM) turbulence. The electron temperature gradient achieves a critical value early in the ELM cycle, concurrent with the appearance of both microtearing modes and ETG modes. Nonlinear ETG simulations demonstrate that the profiles lie at a nonlinear critical gradient. The nominal profiles are stable to KBM, but moderate increases in β are sufficient to surpass the KBM threshold. Certain aspects of the dynamics support the premise of KBM-constrained pedestal evolution; the density and temperature profiles separately undergo large changes, but in a manner that keeps the pressure profile constant and near the KBM limit.

  15. Estimation of sheath potentials in front of ASDEX upgrade ICRF antenna with SSWICH asymptotic code

    SciTech Connect

    Křivská, A.; Colas, L.; Milanesio, D.

    2015-12-10

    Multi-megawatt Ion Cyclotron Range of Frequencies (ICRF) heating became problematic in ASDEX Upgrade (AUG) tokamak after coating of ICRF antenna limiters and other plasma facing components by tungsten. Strong impurity influx was indeed produced at levels of injected power markedly lower than in the previous experiments. It is assumed that the impurity production is mainly driven by parallel component of Radio-Frequency (RF) antenna electric near-field E// that is rectified in sheaths. In this contribution we estimate poloidal distribution of sheath Direct Current (DC) potential in front of the ICRF antenna and simulate its relative variations over the parametric scans performed during experiments, trying to reproduce some of the experimental observations. In addition, relative comparison between two types of AUG ICRF antenna configurations, used for experiments in 2014, has been performed. For this purpose we use the Torino Polytechnic Ion Cyclotron Antenna (TOPICA) code and asymptotic version of the Self-consistent Sheaths and Waves for Ion Cyclotron Heating (SSWICH) code. Further, we investigate correlation between amplitudes of the calculated oscillating sheath voltages and the E// fields computed at the lateral side of the antenna box, in relation with a heuristic antenna design strategy at IPP Garching to mitigate RF sheaths.

  16. Effect of collisional heat transfer in ICRF power modulation experiment on ASDEX Upgrade

    SciTech Connect

    Tsujii, N.; D'Inca, R.; Bilato, R.; Bobkov, Vl. V.; Brambilla, M.; Schneider, P.; Noterdaeme, J.-M.; Van Eester, D.; Lerche, E. A.; Jaeger, E. F.; Collaboration: ASDEX Upgrade Team

    2014-02-12

    ICRF (ion cyclotron range of frequencies) heating experiments were performed in D-H plasmas at various H concentrations on ASDEX Upgrade. The rf power was modulated to measure the electron power deposition profile from electron temperature modulation. To minimize the contribution from indirect collisional heating and the effect of radial transport, the rf power was modulated at 50 Hz. However, peaking of electron temperature modulation was still observed around the hydrogen cyclotron resonance indicating collisional heating contribution. Time dependent simulation of the hydrogen distribution function was performed for the discharges, using the full-wave code AORSA (E.F. Jaeger, et al., Phys. Plasmas, Vol. 8, page 1573 (2001)) coupled to the Fokker-Planck code CQL3D (R.W. Harvey, et al., Proc. IAEA (1992)). In the present experimental conditions, it was found that modulation of the collisional heating was comparable to that of direct wave damping. Impact of radial transport was also analyzed and found to appreciably smear out the modulation profile and reduce the phase delay.

  17. Pellet refuelling of particle loss due to ELM mitigation with RMPs in the ASDEX Upgrade tokamak at low collisionality

    NASA Astrophysics Data System (ADS)

    Valovič, M.; Lang, P. T.; Kirk, A.; Suttrop, W.; Cavedon, M.; Cseh, G.; Dunne, M.; Fischer, L. R.; Garzotti, L.; Guimarais, L.; Kocsis, G.; Mlynek, A.; Plőckl, B.; Scannell, R.; Szepesi, T.; Tardini, G.; Thornton, A.; Viezzer, E.; Wolfrum, E.; the ASDEX Upgrade Team; the EUROfusion MST1 Team

    2016-06-01

    The complete refuelling of the plasma density loss (pump-out) caused by mitigation of edge localised modes (ELMs) is demonstrated on the ASDEX Upgrade tokamak. The plasma is refuelled by injection of frozen deuterium pellets and ELMs are mitigated by external resonant magnetic perturbations (RMPs). In this experiment relevant dimensionless parameters, such as relative pellet size, relative RMP amplitude and pedestal collisionality are kept at the ITER like values. Refuelling of density pump out of the size of Δ n/n∼ 30% requires a factor of two increase of nominal fuelling rate. Energy confinement and pedestal temperatures are not restored to pre-RMP values by pellet refuelling.

  18. H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET

    SciTech Connect

    Beurskens, M. N. A.; Lomas, P.; Saarelma, S.; Scannell, R.; Balboa, I.; Brix, M.; Flanagan, J.; Giroud, C.; Kempenaars, M.; Maddison, G.; McDonald, D.; Schneider, P. A.; Wolfrum, E.; Maggi, C. F.; Frassinetti, L.; Nunes, I.

    2011-05-15

    Multidevice pedestal scaling experiments in the DIII-D, ASDEX Upgrade (AUG), and JET tokamaks are presented in order to test two plasma physics pedestal width models. The first model proposes a scaling of the pedestal width {Delta}/a {proportional_to} {rho}*{sup 1/2} to {rho}* based on the radial extent of the pedestal being set by the point where the linear turbulence growth rate exceeds the ExB velocity. In the multidevice experiment where {rho}* at the pedestal top was varied by a factor of four while other dimensionless parameters where kept fixed, it has been observed that the temperature pedestal width in real space coordinates scales with machine size, and that therefore the gyroradius scaling suggested by the model is not supported by the experiments. The density pedestal width is not invariant with {rho}* which after comparison with a simple neutral fuelling model may be attributed to variations in the neutral fuelling patterns. The second model, EPED1, is based on kinetic ballooning modes setting the limit of the radial extent of the pedestal region and leads to {Delta}{sub {psi} {proportional_to}} {beta}{sub p}{sup 1/2}. All three devices show a scaling of the pedestal width in normalised poloidal flux as {Delta}{sub {psi} {proportional_to}} {beta}{sub p}{sup 1/2}, as described by the kinetic ballooning model; however, on JET and AUG, this could not be distinguished from an interpretation where the pedestal is fixed in real space. Pedestal data from all three devices have been compared with the predictive pedestal model EPED1 and the model produces pedestal height values that match the experimental data well.

  19. Collection strategy, inner morphology, and size distribution of dust particles in ASDEX Upgrade

    SciTech Connect

    M. Balden; N. Endstrasser; P. W. Humrickhouse; V. Rohde; M. Rasinski; U. von Toussaint; S. Elgeti; R. Neu

    2014-04-01

    The dust collection and analysis strategy in ASDEX Upgrade (AUG) is described. During five consecutive operation campaigns (2007–2011), Si collectors were installed, which were supported by filtered vacuum sampling and collection with adhesive tapes in 2009. The outer and inner morphology (e.g. shape) and elemental composition of the collected particles were analysed by scanning electron microscopy. The majority of the ~50?000 analysed particles on the Si collectors of campaign 2009 contain tungsten—the plasma-facing material in AUG—and show basically two different types of outer appearance: spheroids and irregularly shaped particles. By far most of the W-dominated spheroids consist of a solid W core, i.e. solidified W droplets. A part of these particles is coated with a low-Z material; a process that seems to happen presumably in the far scrape-off layer plasma. In addition, some conglomerates of B, C and W appear as spherical particles after their contact with plasma. By far most of the particles classified as B-, C- and W-dominated irregularly shaped particles consist of the same conglomerate with varying fraction of embedded W in the B–C matrix and some porosity, which can exceed 50%. The fragile structures of many conglomerates confirm the absence of intensive plasma contact. Both the ablation and mobilization of conglomerate material and the production of W droplets are proposed to be triggered by arcing. The size distribution of each dust particle class is best described by a log-normal distribution allowing an extrapolation of the dust volume and surface area. The maximum in this distribution is observed above the resolution limit of 0.28 µm only for the W-dominated spheroids, at around 1 µm. The amount of W-containing dust is extrapolated to be less than 300 mg on the horizontal areas of AUG.

  20. Influence of externally applied magnetic perturbations on neoclassical tearing modes at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Fietz, S.; Bergmann, A.; Classen, I.; Maraschek, M.; Garcia-Muñoz, M.; Suttrop, W.; Zohm, H.; the ASDEX Upgrade Team

    2015-01-01

    The influence of externally applied magnetic perturbations (MPs) on neoclassical tearing modes (NTM) and the plasma rotation in general is investigated at the ASDEX Upgrade tokamak (AUG). The low n resonant components of the applied field exert local torques and influence the stability of NTMs. The non-resonant components of the error field do not influence MHD modes directly but slow down the plasma rotation globally due to a neoclassical toroidal viscous torque (NTV). Both components slow down the plasma rotation, which in consequence increases the probability for the appearance of locked modes. To investigate the impact of externally applied MPs on already existing modes and the influence on the rotation profile, experimental observations are compared to modelling results. The model used here solves a coupled equation system that includes the Rutherford equation and the equation of motion, taking into account the resonant effects and the resistive wall. It is shown that the NTV torque can be neglected in this modelling. To match the experimental frequency evolution of the mode the MP field strength at the resonant surface has to be increased compared to the vacuum approximation. This leads to an overestimation of the stabilizing effect on the NTMs. The reconstruction of the entire rotation profile via the equation of motion including radial dependencies, confirms that the NTV is negligibly small and that small resonant torques at different resonant surfaces have the same effect as one large one. This modelling suggests that in the experiment resonant torques at different surfaces are acting and slowing down the plasma rotation requiring a smaller torque at the specific resonant surface of the NTM. This additionally removes the overestimated influence on the island stability, whereas the braking of the island's rotation is caused by the sum of all torques. Consequently, to describe the effect of MPs on the evolution of one island, all other islands and the

  1. The effect of off-axis neutral beam injection on sawtooth stability in ASDEX Upgrade and Mega-Ampere Spherical Tokamak

    SciTech Connect

    Chapman, I. T.; de Bock, M. F.; Pinches, S. D.; Turnyanskiy, M. R.

    2009-07-15

    Sawtooth behavior has been investigated in plasmas heated with off-axis neutral beam injection in ASDEX Upgrade [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)] and the Mega-Ampere Spherical Tokamak (MAST) [A. Sykes et al., Nucl. Fusion 41, 1423 (2001)]. Provided that the fast ions are well confined, the sawtooth period is found to decrease as the neutral beam is injected further off-axis. Drift kinetic modeling of such discharges qualitatively shows that the passing fast ions born outside the q=1 rational surface can destabilize the n=1 internal kink mode, thought to be related to the sawtooth instability. This effect can be enhanced by optimizing the deposition of the off-axis beam energetic particle population with respect to the mode location.

  2. The role of carbon and nitrogen on the H-mode confinement in ASDEX Upgrade with a metal wall

    NASA Astrophysics Data System (ADS)

    Beurskens, M. N. A.; Dunne, M. G.; Frassinetti, L.; Bernert, M.; Cavedon, M.; Fischer, R.; Järvinen, A.; Kallenbach, A.; Laggner, F. M.; McDermott, R. M.; Potzel, S.; Schweinzer, J.; Tardini, G.; Viezzer, E.; Wolfrum, E.; the ASDEX Upgrade Team; the EUROfusion MST1 team

    2016-05-01

    Carbon (CD4) and nitrogen (N2) have been seeded in ASDEX Upgrade (AUG) with a tungsten wall and have both led to a 20–30% confinement improvement. The reference plasma is a standard target plasma with I p /B T  =  1 MA/2.5 T, total input power P tot ~ 12 MW and normalized pressure of β N ~ 1.8. Carbon and nitrogen are almost perfectly exchangeable for the core, pedestal and divertor plasma in this experiment where impurity concentrations of C and N of 2% are achieved and Z eff only mildly increases from ~1.3 to ~1.7. As the radiation potentials of C and N are similar and peak well below 100 eV, both impurities act as divertor radiators and radiate well outside the pedestal region. The outer divertor is purposely kept in an attached state when C and N are seeded to avoid confinement degradation by detachment. As reported in earlier publications for nitrogen, carbon is also seen to reduce the high field side high density (the so-called HFSHD) in the scrape off layer above the inner divertor strike point by about 50%. This is accompanied by a confinement improvement for both low (δ ~ 0.25) and high (δ ~ 0.4) triangularity configurations for both seeding gases, due to an increase of pedestal temperature and stiff core temperature profiles. The electron density profiles show no apparent change due to the seeding. As an orthogonal effect, increasing the triangularity leads to an additionally increased pedestal density, independent of the impurity seeding. This experiment further closes the gap in understanding the confinement differences observed in carbon and metal wall devices; the absence of carbon can be substituted by nitrogen which leads to a similar confinement benefit. So far, no definite physics explanation for the confinement enhancement has been obtained, but the experimental observations in this paper provide input for further model development.

  3. Optimization of the FM-CW reflectometry W-band antenna for core density profile measurements on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Hacquin, S.; Wagner, D.; Manso, M.; Borreicho, J.; Farinha, L.

    2003-03-01

    A numerical study of the focused hog-horn antenna used for the W-band channel of the ASDEX Upgrade frequency modulated continuous wave reflectometry system is performed here. A mode matching code is used to accuretely model wave propagation in waveguide and antenna structures. Then the field distribution (amplitude and phase) in the horn aperture given by this code is used as an input for other codes computing wave propagation in the plasma. Evaluating the received energy in the antenna, we first analyze plasma effects as the nonalignment between the antenna and the plasma equatorial plane. We show in the case of an unfocused antenna that ray-tracing results are in qualitative agreement with full wave calculations. Simulations also confirm that hog-horn antennas allow improving the measurement performances in comparison with unfocused antennas. The role of location of the focusing point of a hog-horn antenna (depending on the antenna design) is then studied. It appears that the focusing point position should be optimized to maximize the energy received in the antenna. Finally, we show that a new design for the W-band antenna on the ASDEX Upgrade broadband reflectometry system could improve the performances of this diagnostic.

  4. Nonaxisymmetric energy deposition pattern on ASDEX upgrade divertor target plates during type-I edge-localized modes.

    PubMed

    Eich, T; Herrmann, A; Neuhauser, J

    2003-11-01

    In the ASDEX Upgrade tokamak, complex power deposition structures on the divertor target plates during type-I edge-localized modes (ELMs) have been discovered by fast (few microseconds), two-dimensional (40 x 40 cm(2)) infrared thermography. In addition to the usual axisymmetric power deposition line near the separatrix, there appear, statistically distributed, several laterally displaced and inclined stripes, mostly well separated from each other and from the main strike zone. These structures are interpreted as footprints of approximately field aligned, helical perturbations at the low field side of the main plasma edge related to the nonlinear ELM evolution. Based on this picture, the ELM related mode structure can be derived from the target load pattern, yielding on average toroidal mode numbers in a range of 8-24. PMID:14611587

  5. Inter-ELM power decay length for JET and ASDEX upgrade: measurement and comparison with heuristic drift-based model.

    PubMed

    Eich, T; Sieglin, B; Scarabosio, A; Fundamenski, W; Goldston, R J; Herrmann, A

    2011-11-18

    Experimental measurements of the SOL power decay length (λ(q)) estimated from analysis of fully attached divertor heat load profiles from two tokamaks, JET and ASDEX Upgrade, are presented. Data was measured by means of infrared thermography. An empirical scaling reveals parametric dependency λ(q) in mm = 0.73B(T)(-0.78)q(cyl)(1.2)P(SOL)(0.1)R(geo)(0), where B(T)(T) describes the toroidal magnetic field, q(cyl) the cylindrical safety factor, P(SOL)(MW) the power crossing the separatrix and R(geo)(m) the major radius of the device. A comparison of these measurements to a heuristic particle drift-based model shows satisfactory agreement in both absolute magnitude and scaling. Extrapolation to ITER gives λ(q) ≃ 1 mm. PMID:22181888

  6. On the role of the edge density profile for the L-H transition power threshold in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Shao, L. M.; Wolfrum, E.; Ryter, F.; Birkenmeier, G.; Laggner, F. M.; Viezzer, E.; Fischer, R.; Willensdorfer, M.; Kurzan, B.; Lunt, T.; the ASDEX Upgrade Team

    2016-02-01

    The L-H transition power threshold ({{P}\\text{L-\\text{H}}} ) in full tungsten (W) wall discharges is lower by 25% compared to those with graphite (C) mix tungsten walls in ASDEX Upgrade (Ryter et al 2013 Nucl. Fusion 53 113003). The lower power threshold in the full tungsten wall discharges has been found to correlate with higher edge density as well as steeper edge density gradient. An estimate of the minimum in the neoclassical radial electric field well inside the separatrix yields a constant value for all analyzed L-H transitions at fixed toroidal magnetic field ({{B}\\text{T}} ). The decrease of the threshold power is explained by the steeper edge density gradient in the discharges with full tungsten wall.

  7. New developments and test of high power transmission components for ECRH on ASDEX-Upgrade and W7-AS

    SciTech Connect

    Empacher, L.; Foerster, W.; Gantenbein, G.; Kasparek, W.; Kumric, H.

    1995-12-31

    The installation of new 140 GHz systems for electron cyclotron heating on the tokamak ASDEX-Upgrade and the stellarator W7-AS with a power of 2 MW each and 3 s pulse length is underway. These systems use gyrotrons, developed by the Institute of Applied Physics, Nizhny Novgorod, and built by Toriy in Russia, as high power mm-wave sources. The gyrotrons can be operated for 3 s with 0.5 MW and for 1 s with 0.7 MW EHF output. The transmission of the millimetre wave power is realized by a combination of beam waveguides and corrugated HE{sub 11} waveguides. Components for transmission and high power diagnostics as well as first results are described together with the system.

  8. Development progress of Correlation ECE and n-T cross-phase angle diagnostics for ASDEX-Upgrade

    NASA Astrophysics Data System (ADS)

    Freethy, Simon; Conway, Garrard; Classen, Ivo; Creely, Alex; White, Anne; Happel, Tim; Vanovac, Branka; ASDEX Upgrade Team

    2015-11-01

    Relative turbulent temperature fluctuation amplitudes can be measured using Correlation ECE (CECE). This technique uses two narrow frequency-band radiometer channels, with an equivalent physical spacing within a turbulent radial correlation length. Correlation techniques select the common turbulent fluctuation while suppressing uncorrelated thermal noise. If such a diagnostic views the same part of the plasma as a reflectometer, then the coherence and cross-phase angle between temperature and density fluctuations can be measured. Two 2nd harmonic, X-mode, CECE radiometers have recently been installed on ASDEX Upgrade, one of which shares the quasi-optical steerable antenna of an existing Doppler reflectometer, i.e with a common line of sight of the plasma. We report on the progress of the installation and preliminary data from both systems.

  9. Fast-ion losses induced by ELMs and externally applied magnetic perturbations in the ASDEX Upgrade tokamak

    NASA Astrophysics Data System (ADS)

    Garcia-Munoz, M.; Äkäslompolo, S.; de Marne, P.; Dunne, M. G.; Dux, R.; Evans, T. E.; Ferraro, N. M.; Fietz, S.; Fuchs, C.; Geiger, B.; Herrmann, A.; Hoelzl, M.; Kurzan, B.; Lazanyi, N.; McDermott, R. M.; Nocente, M.; Pace, D. C.; Rodriguez-Ramos, M.; Shinohara, K.; Strumberger, E.; Suttrop, W.; Van Zeeland, M. A.; Viezzer, E.; Willensdorfer, M.; Wolfrum, E.

    2013-12-01

    Phase-space time-resolved measurements of fast-ion losses induced by edge localized modes (ELMs) and ELM mitigation coils have been obtained in the ASDEX Upgrade tokamak by means of multiple fast-ion loss detectors (FILDs). Filament-like bursts of fast-ion losses are measured during ELMs by several FILDs at different toroidal and poloidal positions. Externally applied magnetic perturbations (MPs) have little effect on plasma profiles, including fast-ions, in high collisionality plasmas with mitigated ELMs. A strong impact on plasma density, rotation and fast-ions is observed, however, in low density/collisionality and q95 plasmas with externally applied MPs. During the mitigation/suppression of type-I ELMs by externally applied MPs, the large fast-ion bursts observed during ELMs are replaced by a steady loss of fast-ions with a broad-band frequency and an amplitude of up to an order of magnitude higher than the neutral beam injection (NBI) prompt loss signal without MPs. Multiple FILD measurements at different positions, indicate that the fast-ion losses due to static 3D fields are localized on certain parts of the first wall rather than being toroidally/poloidally homogeneously distributed. Measured fast-ion losses show a broad energy and pitch-angle range and are typically on banana orbits that explore the entire pedestal/scrape-off-layer (SOL). Infra-red measurements are used to estimate the heat load associated with the MP-induced fast-ion losses. The heat load on the FILD detector head and surrounding wall can be up to six times higher with MPs than without 3D fields. When 3D fields are applied and density pump-out is observed, an enhancement of the fast-ion content in the plasma is typically measured by fast-ion D-alpha (FIDA) spectroscopy. The lower density during the MP phase also leads to a deeper beam deposition with an inward radial displacement of ≈2 cm in the maximum of the beam emission. Orbit simulations are used to test different models for 3D

  10. Laboratory Astrophysics on ASDEX Upgrade: Measurements and Analysis of K-Shell O, F, and Ne Spectra in the 9-20 A region

    SciTech Connect

    Hansen, S B; Fournier, K B; Finkenthal, M; Smith, R; Puetterich, T; Neu, R

    2006-05-01

    High-resolution measurements of K-shell emission from O, F, and Ne have been performed at the ASDEX Upgrade tokamak in Garching, Germany. Independently measured temperature and density profiles of the plasma provide a unique test bed for model validation. We present comparisons of measured spectra with calculations based on transport and collisional-radiative models and discuss the reliability of commonly used diagnostic line ratios.

  11. Laboratory astrophysics on ASDEX Upgrade: Measurements and analysis of K-shell O, F, and Ne spectra in the 9 - 20 A region

    NASA Technical Reports Server (NTRS)

    Hansen, S. B.; Fournier, K. B.; Finkenthal, M. J.; Smith, R.; Puetterich, T.; Neu, R.

    2006-01-01

    High-resolution measurements of K-shell emission from O, F, and Ne have been performed at the ASDEX Upgrade tokamak in Garching, Germany. Independently measured temperature and density profiles of the plasma provide a unique test bed for model validation. We present comparisons of measured spectra with calculations based on transport and collisional-radiative models and discuss the reliability of commonly used diagnostic line ratios.

  12. 3D ELM fluctuation measurements with the new dual array ECE-Imaging diagnostic on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Classen, Ivo; Vanovac, Branka; Domier, Calvin; Luhmann, Neville; Bogomolov, Anton; Suttrop, Wolfgang; Tobias, Benjamin; ASDEX Upgrade Team

    2015-11-01

    In a major upgrade, the (2D) electron cyclotron emission imaging diagnostic (ECE-Imaging) at ASDEX Upgrade (AUG) has been equipped with a second detector array, and has been successfully commissioned. The two detector arrays observe the plasma through the same vacuum window, both under a slight toroidal angle, to enable quasi-3D measurements of the electron temperature. The system measures a total of 288 channels, in two toroidally separated 2D arrays of approximately 50 cm vertically by 10 cm radially. The toroidal separation between the two poloidal observation planes is about 40 cm, such that the majority of the field lines is observed by both arrays simultaneously, thereby enabling a direct measurement of the 3D properties of plasma instabilities like ELM filaments. The toroidal separation of 40 cm is sufficient for the accurate measurement of both phase differences and transit times of (rotating) plasma structures, enabling a distinction between time varying 2D structures and true 3D structures (not possible with 2D diagnostics). The research will mainly focus on the investigation of the 3D structure of the temperature fluctuations related to edge localized modes (ELMs), in particular precursors and filaments. The first results on ELMs will be reported.

  13. Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak

    NASA Astrophysics Data System (ADS)

    García-Muñoz, M.; Fahrbach, H.-U.; Zohm, H.; ASDEX Upgrade Team

    2009-05-01

    A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)].

  14. Quantification of the impact of large and small-scale instabilities on the fast-ion confinement in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Geiger, B.; Weiland, M.; Mlynek, A.; Reich, M.; Bock, A.; Dunne, M.; Dux, R.; Fable, E.; Fischer, R.; Garcia-Munoz, M.; Hobirk, J.; Hopf, C.; Nielsen, S.; Odstrcil, T.; Rapson, C.; Rittich, D.; Ryter, F.; Salewski, M.; Schneider, P. A.; Tardini, G.; Willensdorfer, M.

    2015-01-01

    The confinement fast ions, generated by neutral beam injection (NBI), has been investigated at the ASDEX Upgrade tokamak. In plasmas that exhibit strong sawtooth crashes, a significant sawtooth-induced internal redistribution of mainly passing fast ions is observed, which is in very good agreement with the theoretical predictions based on the Kadomtsev model. Between the sawtooth crashes, the fishbone modes are excited which, however, do not cause measurable changes in the global fast-ion population. During experiments with on- and off-axis NBI and without strong magnetohydrodynamic (MHD) modes, the fast-ion measurements agree very well with the neo-classical predictions. This shows that the MHD-induced (large-scale), as well as a possible turbulence-induced (small-scale) fast-ion transport is negligible under these conditions. However, in discharges performed to study the off-axis NBI current drive efficiency with up to 10 MW of heating power, the fast-ion measurements agree best with the theoretical predictions that assume a weak level anomalous fast-ion transport. This is also in agreement with measurements of the internal inductance, a Motional Stark Effect diagnostic and a novel polarimetry diagnostic: the fast-ion driven current profile is clearly modified when changing the NBI injection geometry and the measurements agree best with the predictions that assume weak anomalous fast-ion diffusion.

  15. Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak

    SciTech Connect

    Garcia-Munoz, M.; Fahrbach, H.-U.; Zohm, H.; Collaboration: ASDEX Upgrade Team

    2009-05-15

    A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)].

  16. Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak.

    PubMed

    García-Muñoz, M; Fahrbach, H-U; Zohm, H

    2009-05-01

    A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)]. PMID:19499603

  17. Pedestal and edge localized mode characteristics with different first wall materials and nitrogen seeding in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Schneider, P. A.; Barrera Orte, L.; Burckhart, A.; Dunne, M. G.; Fuchs, C.; Gude, A.; Kurzan, B.; Suttrop, W.; Wolfrum, E.; the ASDEX Upgrade Team

    2015-01-01

    A comparison of ASDEX Upgrade (AUG) discharges performed with carbon and the full tungsten wall shows that the pedestal performance at low triangularity is not altered without gas puffing. The pedestal electron pressure is the same for both wall materials as is the confinement. With the tungsten wall the natural density is higher even without an additional gas puff. In typical operation with gas puffing the density is again higher in tungsten. This results in a higher collisionality with the tungsten wall. Pedestal pressure and plasma confinement, however, are not degraded until very large amounts of deuterium are puffed. The edge localized mode (ELM) crash in typical AUG discharges is observed to be composed of two independent phases. This is observed for both the carbon and the tungsten wall. The 1st phase of the crash is unaffected by scans of the plasma parameters as long as the pedestal pressure remains constant. The duration of the 2nd phase is strongly anti-correlated with the separatrix density and can be suppressed by the application of nitrogen seeding for divertor cooling. A consistent explanation for the two phases of the ELM crash does not seem possible when considering only the pre-ELM pedestal profiles. The scrape off layer (SOL) plasma provides the necessary free parameter for a consistent explanation, indicating the importance of the SOL in understanding the ELM crash evolution.

  18. Interpretation of the effects of electron cyclotron power absorption in pre-disruptive tokamak discharges in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Nowak, S.; Lazzaro, E.; Esposito, B.; Granucci, G.; Maraschek, M.; Sauter, O.; Zohm, H.; Brunetti, D.; ASDEX Upgrade Team

    2012-09-01

    Tokamak disruptions are events of fatal collapse of the magnetohydrodynamic (MHD) confinement configuration, which cause a rapid loss of the plasma thermal energy and the impulsive release of magnetic energy and heat on the tokamak first wall components. The physics of the disruptions is very complex and non-linear, strictly associated with the dynamics of magnetic tearing perturbations. The crucial problem of the response to the effects of localized heat deposition and current driven by external (rf) sources to avoid or quench the MHD tearing instabilities has been investigated both experimentally and theoretically on the ASDEX Upgrade tokamak. The analysis of the conditions under which a disruption can be prevented by injection of electron cyclotron (EC) rf power, or, alternatively, may be caused by it, shows that the local EC heating can be more significant than EC current drive in ensuring neoclassical tearing modes (NTMs) stability, due to two main reasons: first, the drop of temperature associated with the island thermal short circuit tends to reduce the neoclassical character of the instability and to limit the EC current drive generation; second, the different effects on the mode evolution of both the location of the power deposition relative to the island separatrix and the island shape deformation lead to less strict requirements of precise power deposition focussing. A contribution to the validation of theoretical models of the events associated with NTM is given and can be used to develop concepts for their control, relevant also for ITER-like scenarios.

  19. Interpretation of the effects of electron cyclotron power absorption in pre-disruptive tokamak discharges in ASDEX Upgrade

    SciTech Connect

    Nowak, S.; Lazzaro, E.; Granucci, G.; Esposito, B.; Maraschek, M.; Zohm, H.; Sauter, O.; Brunetti, D.; Collaboration: ASDEX Upgrade Team

    2012-09-15

    Tokamak disruptions are events of fatal collapse of the magnetohydrodynamic (MHD) confinement configuration, which cause a rapid loss of the plasma thermal energy and the impulsive release of magnetic energy and heat on the tokamak first wall components. The physics of the disruptions is very complex and non-linear, strictly associated with the dynamics of magnetic tearing perturbations. The crucial problem of the response to the effects of localized heat deposition and current driven by external (rf) sources to avoid or quench the MHD tearing instabilities has been investigated both experimentally and theoretically on the ASDEX Upgrade tokamak. The analysis of the conditions under which a disruption can be prevented by injection of electron cyclotron (EC) rf power, or, alternatively, may be caused by it, shows that the local EC heating can be more significant than EC current drive in ensuring neoclassical tearing modes (NTMs) stability, due to two main reasons: first, the drop of temperature associated with the island thermal short circuit tends to reduce the neoclassical character of the instability and to limit the EC current drive generation; second, the different effects on the mode evolution of both the location of the power deposition relative to the island separatrix and the island shape deformation lead to less strict requirements of precise power deposition focussing. A contribution to the validation of theoretical models of the events associated with NTM is given and can be used to develop concepts for their control, relevant also for ITER-like scenarios.

  20. Comparison of experiment and models of geodesic acoustic mode frequency and amplitude geometric scaling in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Simon, P.; Conway, G. D.; Stroth, U.; Biancalani, A.; Palermo, F.; the ASDEX Upgrade Team

    2016-04-01

    In a set of dedicated ASDEX Upgrade shape-scan experiments, the influence of plasma geometry on the frequency and amplitude behaviour of the geodesic acoustic mode (GAM), measured by Doppler reflectometry, is studied. In both limiter and divertor configurations, the plasma elongation was varied between circular and highly elongated states (1.1<κ <1.8 ). Also, the edge safety factor was scanned between 3  <  q  <  5. The GAM frequency {ω\\text{GAM}} and amplitude are used to test several models (heuristic, fluid and gyrokinetic based), which incorporate various plasma geometry effects. The experimentally observed effect of decreasing {ω\\text{GAM}} with increasing κ is predicted by most models. Other geometric factors, such as inverse aspect ratio ε and Shafranov shift gradient {Δ\\prime} are also seen to be influential in determining a reliable lower {ω\\text{GAM}} boundary. The GAM amplitude is found to vary with boundary elongation {κ\\text{b}} and safety factor q. The collisional damping is compared to multiple models for the collisionless damping. Collisional damping appears to play a stronger role in the divertor configuration, while collisional and collisionless damping both may contribute to the GAM amplitude in the limiter configuration.

  1. Toroidal modelling of resonant magnetic perturbations response in ASDEX-Upgrade: coupling between field pitch aligned response and kink amplification

    NASA Astrophysics Data System (ADS)

    Ryan, D. A.; Liu, Y. Q.; Kirk, A.; Suttrop, W.; Dudson, B.; Dunne, M.; Fischer, R.; Fuchs, J. C.; Garcia-Munoz, M.; Kurzan, B.; Piovesan, P.; Reinke, M.; Willensdorfer, M.; the ASDEX-Upgrade Team; the EUROfusion MST1 Team

    2015-09-01

    Using the MARS-F code (Liu et al 2000 Phys. Plasmas 7 3681), the single fluid resistive MHD plasma response to applied n   =   2 resonant magnetic perturbations is computed, for a plasma discharge in the ASDEX-Upgrade tokamak. The computation predicts strong kink amplification, as previously predicted in DIII-D (Haskey et al 2014 Plasma Phys. Control. Fusion 56 035005), which is strongly dependent on the toroidal phase shift between the upper and lower coils, Δ {φ\\text{ul}} . In particular, edge localised low n peeling modes with poloidal mode numbers just above pitch resonance—a subset of the kink response—are amplified. The robustness of the amplified peeling response with respect to truncation of the X point is investigated, by recomputing the plasma response for a range of edge geometries. It is found that the computed peeling response, when plotted against the safety factor, is not sensitive to the numerical truncation near the X point. It is also predicted that near the plasma edge where resistivity is large, the pitch aligned components are finite and also strongly dependent on Δ {φ\\text{ul}} . A previous proposal that the amplified peeling response may indirectly drive the pitch aligned components by spectral proximity (Lanctot et al 2013 Nucl. Fusion 53 083019), is investigated by numerically applying magnetic perturbations of a single poloidal harmonic, as a boundary condition at the plasma edge. It is found that poloidal harmonic coupling causes harmonics to couple to and drive harmonics directly beneath them spectrally, and also that the pitch aligned components can be driven by this mechanism. This suggests that it is quite possible that the amplified low n peeling response can drive the pitch aligned components when it is strongly amplified, which would alter the coil configuration for optimum plasma stochastization, with implications for ELM control by RMPs.

  2. Experimental analysis and WallDYN simulations of the global nitrogen migration in ASDEX Upgrade L-mode discharges

    NASA Astrophysics Data System (ADS)

    Meisl, G.; Schmid, K.; Oberkofler, M.; Krieger, K.; Lisgo, S. W.; Aho-Mantila, L.; Reimold, F.; Lunt, T.; ASDEX Upgrade Team

    2016-03-01

    This work presents ASDEX Upgrade experiments, where the nitrogen deposition and re-erosion on divertor manipulator samples and the effect of its transport through the plasma were studied. These results are compared to WallDYN-DIVIMP simulations based on SOLPS plasma backgrounds and employing an improved WallDYN model, which includes the effusion of nitrogen from saturated surfaces. On one hand, this allows the WallDYN code and the new saturation model with a comprehensive data set to be benchmarked, on the other hand the simulations help in the interpretation of the experimental results. Both, experimental results and simulations, show that the N content in the region of the outer strike line reaches its steady-state value within one discharge. The simulations also reproduce the experimentally observed nitrogen content in samples exposed to N2-seeded discharges. With respect to the boron deposition, the nitrogen deposition in a non-seeded discharge and the re-erosion of nitrogen discrepancies to the WallDYN-DIVIMP simulations are observed. Based on SDTrimSP simulations, these are attributed to the missing depth resolution of the WallDYN surface model. A detailed comparison of spectroscopic measurements to WallDYN simulations, based on a novel synthetic spectroscopy diagnostic for WallDYN, shows that the nitrogen fluxes in the plasma are well described by the simulations. From a comparison of several WallDYN-DIVIMP simulations employing customized onion-skin model plasma backgrounds the physical processes controlling the nitrogen concentration in the core plasma and the applicability of onion-skin model plasma backgrounds are discussed. From these simulations the private flux zone with the gas valve, the outer baffle and the high field side main wall are identified as the main sources for the nitrogen content of the core plasma.

  3. High power ECRH and ECCD in moderately collisional ASDEX Upgrade Hmodes and status of EC system upgrade

    NASA Astrophysics Data System (ADS)

    Stober, J.; Sommer, F.; Angioni, C.; Bock, A.; Fable, E.; Leuterer, F.; Monaco, F.; Müller, F.; Münich, S.; Petzold, B.; Poli, E.; Schubert, M.; Schütz, H.; Wagner, D.; Zohm, H.; Kasparek, W.; Plaum, B.; Meier, A.; Scherer, Th.; Strauß, D.; Jelonnek, J.; Thumm, M.; Litvak, A.; Denisov, G. G.; Chirkov, A. V.; Tai, E. M.; Popov, L. G.; Nichiporenko, V. O.; Myasnikov, V. E.; Soluyanova, E. A.; Malygin, V.

    2015-03-01

    This contribution deals with H-modes with significant heat exchange between electrons and ions, but which can still show large differences between electron and ion-temperatures especially inside half minor radius. These conditions are referred to as moderately collisional. A systematic study shows that an increasing fraction of electron heating increases the transport in the ion channel mainly due to the dependence of the ITG dominated ion transport on the ratio Te/Ti in agreement with modeling. The rotational shear in the plasmas under study was so small that it hardly influences ITG stability, such that variations of the rotation profile due to a change of the heating method were of minor importance. These findings connect to studies of advanced tokamak scenarios using ECCD as a tool to modify the q-profile. The electron heating connected to the ECCD tends to increase the transport in the ion channel quite in contrast to the goal to operate at reduced current but with increased confinement. The confinement only increases as the fraction of ion heating is increased by adding more NBI. An ITER case was modeled as well. Due to the larger value of νei ・ τE the ratio Te/Ti is only moderately reduced even with strong electron heating and the confinement reduction is small even for the hypothetic case of using only ECRH as additional heating. Finally the paper discusses the ongoing upgrade of the AUG ECRH-system.

  4. Profile measurements of the electron temperature on the ASDEX Upgrade, COMPASS, and ISTTOK tokamak using Thomson scattering, triple, and ball-pen probes

    NASA Astrophysics Data System (ADS)

    Adamek, J.; Müller, H. W.; Silva, C.; Schrittwieser, R.; Ionita, C.; Mehlmann, F.; Costea, S.; Horacek, J.; Kurzan, B.; Bilkova, P.; Böhm, P.; Aftanas, M.; Vondracek, P.; Stöckel, J.; Panek, R.; Fernandes, H.; Figueiredo, H.

    2016-04-01

    The ball-pen probe (BPP) technique is used successfully to make profile measurements of the electron temperature on the ASDEX Upgrade (Axially Symmetric Divertor Experiment), COMPASS (COMPact ASSembly), and ISTTOK (Instituto Superior Tecnico TOKamak) tokamak. The electron temperature is provided by a combination of the BPP potential (ΦBPP) and the floating potential (Vfl) of the Langmuir probe (LP), which is compared with the Thomson scattering diagnostic on ASDEX Upgrade and COMPASS. Excellent agreement between the two diagnostics is obtained for circular and diverted plasmas and different heating mechanisms (Ohmic, NBI, ECRH) in deuterium discharges with the same formula Te = (ΦBPP - Vfl)/2.2. The comparative measurements of the electron temperature using BPP/LP and triple probe (TP) techniques on the ISTTOK tokamak show good agreement of averaged values only inside the separatrix. It was also found that the TP provides the electron temperature with significantly higher standard deviation than BPP/LP. However, the resulting values of both techniques are well in the phase with the maximum of cross-correlation function being 0.8.

  5. Profile measurements of the electron temperature on the ASDEX Upgrade, COMPASS, and ISTTOK tokamak using Thomson scattering, triple, and ball-pen probes.

    PubMed

    Adamek, J; Müller, H W; Silva, C; Schrittwieser, R; Ionita, C; Mehlmann, F; Costea, S; Horacek, J; Kurzan, B; Bilkova, P; Böhm, P; Aftanas, M; Vondracek, P; Stöckel, J; Panek, R; Fernandes, H; Figueiredo, H

    2016-04-01

    The ball-pen probe (BPP) technique is used successfully to make profile measurements of the electron temperature on the ASDEX Upgrade (Axially Symmetric Divertor Experiment), COMPASS (COMPact ASSembly), and ISTTOK (Instituto Superior Tecnico TOKamak) tokamak. The electron temperature is provided by a combination of the BPP potential (ΦBPP) and the floating potential (Vfl) of the Langmuir probe (LP), which is compared with the Thomson scattering diagnostic on ASDEX Upgrade and COMPASS. Excellent agreement between the two diagnostics is obtained for circular and diverted plasmas and different heating mechanisms (Ohmic, NBI, ECRH) in deuterium discharges with the same formula Te = (ΦBPP - Vfl)/2.2. The comparative measurements of the electron temperature using BPP/LP and triple probe (TP) techniques on the ISTTOK tokamak show good agreement of averaged values only inside the separatrix. It was also found that the TP provides the electron temperature with significantly higher standard deviation than BPP/LP. However, the resulting values of both techniques are well in the phase with the maximum of cross-correlation function being 0.8. PMID:27131677

  6. Toroidal modelling of RMP response in ASDEX Upgrade: coil phase scan, q 95 dependence, and toroidal torques

    NASA Astrophysics Data System (ADS)

    Liu, Yueqiang; Ryan, D.; Kirk, A.; Li, Li; Suttrop, W.; Dunne, M.; Fischer, R.; Fuchs, J. C.; Kurzan, B.; Piovesan, P.; Willensdorfer, M.; the ASDEX Upgrade Team; the EUROfusion MST1 Team

    2016-05-01

    The plasma response to the vacuum resonant magnetic perturbation (RMP) fields, produced by the ELM control coils in ASDEX Upgrade experiments, is computationally modelled using the MARS-F/K codes (Liu et al 2000 Phys. Plasmas 7 3681, Liu et al 2008 Phys. Plasmas 15 112503). A systematic investigation is carried out, considering various plasma and coil configurations as in the ELM control experiments. The low q plasmas, with {{q}95}∼ 3.8 (q 95 is the safety factor q value at 95% of the equilibrium poloidal flux), responding to low n (n is the toroidal mode number) field perturbations from each single row of the ELM coils, generates a core kink amplification effect. Combining two rows, with different toroidal phasing, thus leads to either cancellation or reinforcement of the core kink response, which in turn determines the poloidal location of the peak plasma surface displacement. The core kink response is typically weak for the n  =  4 coil configuration at low q, and for the n  =  2 configuration but only at high q ({{q}95}∼ 5.5 ). A phase shift of around 60 degrees for low q plasmas, and around 90 degrees for high q plasmas, is found in the coil phasing, between the plasma response field and the vacuum RMP field, that maximizes the edge resonant field component. This leads to an optimal coil phasing of about 100 (‑100) degrees for low (high) q plasmas, that maximizes both the edge resonant field component and the plasma surface displacement near the X-point of the separatrix. This optimal phasing closely corresponds to the best ELM mitigation observed in experiments. A strong parallel sound wave damping moderately reduces the core kink response but has minor effect on the edge peeling response. For low q plasmas, modelling shows that both the resonant electromagnetic torque and the neoclassical toroidal viscous (NTV) torque (due to the presence of 3D magnetic field perturbations) contribute to the toroidal flow damping, in particular near the

  7. Novel mono-static arrangement of the ASDEX Upgrade high field side reflectometers compatible with electron cyclotron resonance heating stray radiation.

    PubMed

    Silva, A; Varela, P; Meneses, L; Manso, M

    2012-10-01

    The ASDEX Upgrade frequency modulated continuous wave broadband reflectometer system uses a mono-static antenna configuration with in-vessel hog-horns and 3 dB directional couplers. The operation of the new electron cyclotron resonance heating (ECRH) launcher and the start of collective Thomson scattering experiments caused several events where the fragile dummy loads inside the high field side directional couplers were damaged, due to excessive power resulting from the ECRH stray fields. In this paper, we present a non-conventional application of the existing three-port directional coupler that hardens the system to the ECRH stray fields and at the same time generates the necessary reference signal. Electromagnetic simulations and laboratory tests were performed to validate the proposed solution and are compared with the in-vessel calibration tests. PMID:23130802

  8. A new B-dot probe-based diagnostic for amplitude, polarization, and wavenumber measurements of ion cyclotron range-of frequency fields on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Ochoukov, R.; Bobkov, V.; Faugel, H.; Fünfgelder, H.; Noterdaeme, J.-M.

    2015-11-01

    A new B-dot probe-based diagnostic has been installed on an ASDEX Upgrade tokamak to characterize ion cyclotron range-of frequency (ICRF) wave generation and interaction with magnetized plasma. The diagnostic consists of a field-aligned array of B-dot probes, oriented to measure fast and slow ICRF wave fields and their field-aligned wavenumber (k//) spectrum on the low field side of ASDEX Upgrade. A thorough description of the diagnostic and the supporting electronics is provided. In order to compare the measured dominant wavenumber of the local ICRF fields with the expected spectrum of the launched ICRF waves, in-air near-field measurements were performed on the newly installed 3-strap ICRF antenna to reconstruct the dominant launched toroidal wavenumbers (ktor). Measurements during a strap current phasing scan in tokamak discharges reveal an upshift in k// as strap phasing is moved away from the dipole configuration. This result is the opposite of the ktor trend expected from in-air near-field measurements; however, the near-field based reconstruction routine does not account for the effect of induced radiofrequency (RF) currents in the passive antenna structures. The measured exponential increase in the local ICRF wave field amplitude is in agreement with the upshifted k//, as strap phasing moves away from the dipole configuration. An examination of discharges heated with two ICRF antennas simultaneously reveals the existence of beat waves at 1 kHz, as expected from the difference of the two antennas' operating frequencies. Beats are observed on both the fast and the slow wave probes suggesting that the two waves are coupled outside the active antennas. Although the new diagnostic shows consistent trends between the amplitude and the phase measurements in response to changes applied by the ICRF antennas, the disagreement with the in-air near-field measurements remains. An electromagnetic model is currently under development to address this issue.

  9. Novel free-boundary equilibrium and transport solver with theory-based models and its validation against ASDEX Upgrade current ramp scenarios

    NASA Astrophysics Data System (ADS)

    Fable, E.; Angioni, C.; Casson, F. J.; Told, D.; Ivanov, A. A.; Jenko, F.; McDermott, R. M.; Medvedev, S. Yu; Pereverzev, G. V.; Ryter, F.; Treutterer, W.; Viezzer, E.; the ASDEX Upgrade Team

    2013-12-01

    Tokamak scenario development requires an understanding of the properties that determine the kinetic profiles in non-steady plasma phases and of the self-consistent evolution of the magnetic equilibrium. Current ramps are of particular interest since many transport-relevant parameters explore a large range of values and their impact on transport mechanisms has to be assessed. To this purpose, a novel full-discharge modelling tool has been developed, which couples the transport code ASTRA (Pereverzev et al 1991 IPP Report 5/42) and the free boundary equilibrium code SPIDER (Ivanov et al 2005 32nd EPS Conf. on Plasma Physics vol 29C (ECA) P-5.063 and http://epsppd.epfl.ch/Tarragona/pdf/P5_063.pdf), utilizing a specifically designed coupling scheme. The current ramp-up phase can be accurately and reliably simulated using this scheme, where a plasma shape, position and current controller is applied, which mimics the one of ASDEX Upgrade. Transport of energy is provided by theory-based models (e.g. TGLF (Staebler et al 2007 Phys. Plasmas 14 055909)). A recipe based on edge-relevant parameters (Scott 2000 Phys. Plasmas 7 1845) is proposed to resolve the low current phase of the current ramps, where the impact of the safety factor on micro-instabilities could make quasi-linear approaches questionable in the plasma outer region. Current ramp scenarios, selected from ASDEX Upgrade discharges, are then simulated to validate both the coupling with the free-boundary evolution and the prediction of profiles. Analysis of the underlying transport mechanisms is presented, to clarify the possible physics origin of the observed L-mode empirical energy confinement scaling. The role of toroidal micro-instabilities (ITG, TEM) and of non-linear effects is discussed.

  10. A new B-dot probe-based diagnostic for amplitude, polarization, and wavenumber measurements of ion cyclotron range-of frequency fields on ASDEX Upgrade.

    PubMed

    Ochoukov, R; Bobkov, V; Faugel, H; Fünfgelder, H; Noterdaeme, J-M

    2015-11-01

    A new B-dot probe-based diagnostic has been installed on an ASDEX Upgrade tokamak to characterize ion cyclotron range-of frequency (ICRF) wave generation and interaction with magnetized plasma. The diagnostic consists of a field-aligned array of B-dot probes, oriented to measure fast and slow ICRF wave fields and their field-aligned wavenumber (k(//)) spectrum on the low field side of ASDEX Upgrade. A thorough description of the diagnostic and the supporting electronics is provided. In order to compare the measured dominant wavenumber of the local ICRF fields with the expected spectrum of the launched ICRF waves, in-air near-field measurements were performed on the newly installed 3-strap ICRF antenna to reconstruct the dominant launched toroidal wavenumbers (k(tor)). Measurements during a strap current phasing scan in tokamak discharges reveal an upshift in k(//) as strap phasing is moved away from the dipole configuration. This result is the opposite of the k(tor) trend expected from in-air near-field measurements; however, the near-field based reconstruction routine does not account for the effect of induced radiofrequency (RF) currents in the passive antenna structures. The measured exponential increase in the local ICRF wave field amplitude is in agreement with the upshifted k(//), as strap phasing moves away from the dipole configuration. An examination of discharges heated with two ICRF antennas simultaneously reveals the existence of beat waves at 1 kHz, as expected from the difference of the two antennas' operating frequencies. Beats are observed on both the fast and the slow wave probes suggesting that the two waves are coupled outside the active antennas. Although the new diagnostic shows consistent trends between the amplitude and the phase measurements in response to changes applied by the ICRF antennas, the disagreement with the in-air near-field measurements remains. An electromagnetic model is currently under development to address this issue. PMID

  11. A new B-dot probe-based diagnostic for amplitude, polarization, and wavenumber measurements of ion cyclotron range-of frequency fields on ASDEX Upgrade

    SciTech Connect

    Ochoukov, R.; Bobkov, V.; Faugel, H.; Fünfgelder, H.; Noterdaeme, J.-M.

    2015-11-15

    A new B-dot probe-based diagnostic has been installed on an ASDEX Upgrade tokamak to characterize ion cyclotron range-of frequency (ICRF) wave generation and interaction with magnetized plasma. The diagnostic consists of a field-aligned array of B-dot probes, oriented to measure fast and slow ICRF wave fields and their field-aligned wavenumber (k{sub //}) spectrum on the low field side of ASDEX Upgrade. A thorough description of the diagnostic and the supporting electronics is provided. In order to compare the measured dominant wavenumber of the local ICRF fields with the expected spectrum of the launched ICRF waves, in-air near-field measurements were performed on the newly installed 3-strap ICRF antenna to reconstruct the dominant launched toroidal wavenumbers (k{sub tor}). Measurements during a strap current phasing scan in tokamak discharges reveal an upshift in k{sub //} as strap phasing is moved away from the dipole configuration. This result is the opposite of the k{sub tor} trend expected from in-air near-field measurements; however, the near-field based reconstruction routine does not account for the effect of induced radiofrequency (RF) currents in the passive antenna structures. The measured exponential increase in the local ICRF wave field amplitude is in agreement with the upshifted k{sub //}, as strap phasing moves away from the dipole configuration. An examination of discharges heated with two ICRF antennas simultaneously reveals the existence of beat waves at 1 kHz, as expected from the difference of the two antennas’ operating frequencies. Beats are observed on both the fast and the slow wave probes suggesting that the two waves are coupled outside the active antennas. Although the new diagnostic shows consistent trends between the amplitude and the phase measurements in response to changes applied by the ICRF antennas, the disagreement with the in-air near-field measurements remains. An electromagnetic model is currently under development to

  12. M3D-C1 simulations of plasma response in ELM-mitigated ASDEX Upgrade and DIII-D discharges

    NASA Astrophysics Data System (ADS)

    Lyons, B. C.; Ferraro, N. M.; Haskey, S. R.; Logan, N. C.

    2015-11-01

    The extended magnetohydrodynamics (MHD) code M3D-C1 is used to study the time-independent, linear response of tokamak equilibria to applied, 3D magnetic perturbations. In doing so, we seek to develop a more complete understanding of what MHD phenomena are responsible for the mitigation and suppression of edge-localized modes (ELMs) and to explain why the success of ELM suppression experiments differs both within a single tokamak and across different tokamaks. We consider such experiments on ASDEX Upgrade and DIII-D. We examine how resonant and non-resonant plasma responses are affected by varying the relative magnitude and phase of sets of magnetic coils. The importance of two-fluid effects, rotation profiles, plasma β, collisionality, bootstrap current profiles, and various numerical parameters are explored. The results are verified against other MHD codes (e.g., IPEC, MARS), correlated to observations of ELM mitigation or suppression, and validated against observed magnetic responses. Work supported in part by US DOE under DE-FC02-04ER54698, DE-AC02-09CH11466, and the FES Postdoctoral Research Program.

  13. Wavenumber-resolved core turbulence studies in the ASDEX Upgrade tokamak and comparison with non-linear gyrokinetic simulations with the GENE code

    NASA Astrophysics Data System (ADS)

    Happel, Tim; Bañón Navarro, Alejandro; Conway, Garrard; Görler, Tobias; Jenko, Frank; Ryter, Francois; Stroth, Ulrich; ASDEX Upgrade Team

    2014-10-01

    Core plasma turbulence determines transport properties and impacts on the efficiency of a fusion reactor. Gyrokinetic codes are developed to predict dominant instabilities and the turbulence level, which causes the observed particle and heat losses. A careful validation of these codes is mandatory to improve the reliability of predictions. To this end, core turbulence is investigated in ASDEX Upgrade by means of Doppler reflectometry, which provides the perpendicular velocity of turbulent structures and their fluctuation level. H-mode discharges have been performed in which ECRH is used to drive the turbulence from the ITG turbulence regime towards the TEM regime. In general, the turbulence level increases from core towards the edge. With increasing R /LTe , core large scale structures show larger fluctuation amplitudes while their phase velocity is altered with respect to that of small structures. Results are compared with gyrokinetic simulations with the GENE code. Linear results show a transition from ITG towards TEM turbulence close to the radial ECRH deposition location. After matching of heat fluxes to results from power balance analysis, the radial trend in the turbulence level is reproduced. The response to additional heating is opposite to the experimental findings.

  14. Improvement of the phase regulation between two amplifiers feeding the inputs of the 3dB combiner in the ASDEX-Upgrade ICRH system

    NASA Astrophysics Data System (ADS)

    Grine, D.; Pompon, F.; Faugel, H.; Funfgelder, H.; Noterdaeme, J. M.; Koch, R.

    2011-12-01

    The present ICRF system at ASDEX Upgrade uses 3dB combiners to forward the combined power of a generator pair to a single line [1]. Optimal output performance is achieved when the voltages at the two input lines of a combiner are equal in amplitude and in phase quadrature. If this requirement is not met, a large amount of power is lost in the dummy loads of the combiner. To minimize losses, it is paramount to reach this phase relationship in a fast and stable way. The current phase regulation system is based on analog phase locked loops circuits. The main limitation of this system is the response time: several tens of milliseconds are needed to achieve a stable state. In order to get rid of the response time limitation of the current system, a new system is proposed based on a multi-channel direct digital synthesis device which is steered by a microcontroller and a software-based controller. The proposed system has been developed and successfully tested on a test-bench. The results show a remarkable improvement in the reduction of the response times. Other significant advantages provided by the new system include greater flexibility for frequency and phase settings, lower cost and a noticeable size reduction of the system.

  15. Direct observations of L-I-H and H-I-L transitions with the X-point reciprocating probe in ASDEX Upgrade

    SciTech Connect

    Müller, S. H.; Manz, P.; Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching ; Stroth, U.; Physics Department E28, Technical University of Munich, 85747 Garching ; Tsalas, M.; Tynan, G. R.

    2014-04-15

    A reciprocating Langmuir probe was used to directly measure the behavior of turbulence and flows in the X-point region during transitions between low-(L) and high-confinement (H) mode in ASDEX Upgrade. The probe traverses the divertor horizontally in 140 ms, typically 2–5 cm below the X-point. Toroidal Mach number, density, floating potential (ϕ{sub f}), and electron temperature (T{sub e}) are measured. In the regime accessible to the probe (P{sub inj}<1.5 MW, line-integrated core density <4×10{sup 19} m{sup −2}), the L-H transition features an intermediate phase (I-phase), characterized by limit-cycle oscillations at 0.5–3 kHz [Conway et al., Phys. Rev. Lett. 106, 065001 (2011)]. The probe measurements reveal that this pulsing affects both the density and the toroidal Mach number. It is present in both the low-(LFS) and high-field sides (HFS) of the scrape-off layer, while high-amplitude broadband turbulence usually dominates the private-flux region. Profile comparisons between L-mode and I-phase show lower density in pulsing regions and small shifts in T{sub e}, directed oppositely on LFS and HFS, which are compensated by shifts in ϕ{sub f} to yield a surprisingly unchanged plasma potential profile. Directly observed L-I-phase transitions reveal that the onset of the pulsing is preceded by a fast 50% density drop in the HFS X-point region. Back transitions to L-mode occur essentially symmetrically, with the pulsing stopping first, followed by a fast recovery to L-mode density levels in the divertor.

  16. Economic enhancement of Western shale oil upgrading

    SciTech Connect

    Bunger, J. W.; Ryu, H.; Jeong, S. Y.

    1989-07-01

    A proof-of-concept study for a novel shale oil refining process was undertaken. This project promises reduced upgrading costs, thereby making shale oil development more feasible for commercialization. The process consists of distillation of raw shale oil into a distillate and residue portion, cracking of the residue by hydropyrolysis, and selective hydrotreating of narrow boiling cuts from the total distillate. Based on models and experimental data, the end product slate is projected to be 34% naphtha, 57% middle distillate, and 10.3% atm residue + coke. Hydrogen addition is 1.3% or 800 scf/bbl. These results are considerably improved over conventional processing, which gives 14% naphtha, 41% middle distillate, and 48.2% residue + coke and hydrogen addition of 3.2% or 2000 scf/bbl. More quantitative data and preliminary economics will be obtained in the next phase of study. 13 refs., 3 figs., 6 tabs.

  17. Upgrades and enhancements for competitive coal-fired boiler systems

    SciTech Connect

    Kitto, J.B. Jr.; Bryk, S.A.; Piepho, J.M.

    1996-12-31

    Deregulation of the electric utility industry is resulting in significant opportunities and challenges for US power generators. Existing coal-fired capacity potentially offers the lowest variable cost power production option if these units are upgraded to optimize capacity, operating cost (including fuel), efficiency, and availability while also meeting today`s stringent emissions control requirements. This paper highlights a variety of boiler system upgrades and enhancements which are being utilized to make aging coal-fired boilers low cost competitors in the 1990s.

  18. EMC3-Eirene simulations of particle- and energy fluxes to main chamber- and divertor plasma facing components in ASDEX Upgrade compared to experiments

    NASA Astrophysics Data System (ADS)

    Lunt, T.; Carralero, D.; Feng, Y.; Birkenmeier, G.; Müller, H. W.; Müller, S.; Wischmeier, M.

    2015-08-01

    We report on first EMC3-Eirene simulations with an extended computational grid including both divertor- and main chamber (MC) 3D wall plasma-facing components (PFCs). In a first step we compare the simulations to low-power L-mode discharges systematically analyzed by Carralero et al., who observed a transition from a low- to a high density regime (Carralero et al., 2014). Case A is a configuration at low density and high clearance, while B is a high density regime configuration at medium clearance. In order to explain the upstream far-SOL ne profiles of B the MC PFCs and an enhanced transport region at ρ = 1.01, …, 1.03 need to be included in the simulations. In a second step we compute the particle-, and power fluxes to the limiter for the realistic geometry, for limiters displaced radially inward and for a toroidally symmetric limiter. Almost the same fraction of power as that to the divertor is absorbed by the MC PFCs in the simulation of case B.

  19. B2-Eirene modelling of ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Coster, D. P.; Schneider, R.; Neuhauser, J.; Bosch, H.-S.; Wunderlich, R.; Fuchs, C.; Mast, F.; Kallenbach, A.; Dux, R.; Becker, G.; Braams, B. J.; Reiter, D.; ASDEX Upgrade Team

    1997-02-01

    The extension of the computational region of the coupled fluid plasma, Monte-Carlo neutrals code, B2-Eirene, to the plasma center is discussed. The simulation of completely detached H-mode plasma is presented, as is the modelling of He and Ne compression.

  20. Divertor efficiency in ASDEX

    NASA Astrophysics Data System (ADS)

    Engelhardt, W.; Becker, G.; Behringer, K.; Campbell, D.; Eberhagen, A.; Fussmann, G.; Gehre, O.; Gierke, G. V.; Glock, E.; Haas, G.; Huang, M.; Karger, F.; Keilhacker, M.; KlÜber, O.; Kornherr, M.; Lisitano, G.; Mayer, H.-M.; Meisel, D.; Müller, E. R.; Murmann, H.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Schneider, F.; Siller, G.; Steuer, K.-H.; Venus, G.; Vernickel, H.; Wagner, F.

    1982-12-01

    The divertor efficiency in ASDEX is discussed for ohmically heated plasmas. The parameters of the boundary layer both in the torus midplane and the divertor chamber have been measured. The results are reasonably well understood in terms of parallel and perpendicular transport. A high pressure of neutral hydrogen builds up in the divertor chamber and Franck-Condon particles recycle back through the divertor throat. Due to dissociation processes the boundary plasma is effectively cooled before it reaches the neutralizer plates. The shielding property of the boundary layer against impurity influx is comparable to that of a limiter plasma. The transport of iron is numerically simulated for an iron influx produced by sputtering of charge exchange neutrals at the wall. The results are consistent with the measured iron concentration. First results from a comparison of the poloidal divertor with toroidally closed limiters (stainless steel, carbon) are given. Diverted discharges are considerably cleaner and easier to create.

  1. Upgrading and enhancing the generator protection system by making use of current digital systems

    SciTech Connect

    Chau, N.H.; Gardell, J.D.; Patel, S.C.

    1996-06-01

    Upgrading of power plant systems and equipment is becoming a major theme for many utilities. Due to operational cost pressures, competitiveness, life extension, and the desire for better productivity, condition assessment programs are being implemented. One aspect of this is the enhancement/upgrade of existing generator protection schemes with digital systems. Traditionally this protection has been provided by a complement of discrete component relays. These relays have included both electromechanical and static types. Considering a digital enhancement/upgrade offers the owner of installed generation equipment several unique advantages. These include more complete machine protection, diagnostics capabilities for greater productivity and maintenance optimization, life extension with minimal implementation, and the operational advantages of sequence of events, present values and communications capabilities.

  2. Developing Multimedia Enhanced Content to Upgrade Subject Content Knowledge of Secondary School Teachers in Tanzania

    ERIC Educational Resources Information Center

    Mtebe, Joel S.; Kibga, Elia Y.; Mwambela, Alfred A.; Kissaka, Mussa M.

    2015-01-01

    The failure rates and lack of interest amongst students in science and mathematics in secondary schools in Tanzania is a serious problem. The Ministry of Education and Vocational Training (MoEVT) implemented a project to enhance and upgrade the pedagogical knowledge and subject content knowledge of teachers in selected difficult topics in science…

  3. Recent upgrades and enhancements of the FEM3A model

    SciTech Connect

    Chan, S.T.

    1994-12-01

    In 1984, the US Army Edgewood Research, Development and Engineering Center began to fund Lawrence Livermore National Laboratory to further develop FEM3, a fully three-dimensional heavy-gas dispersion model, as a research tool for studying the atmospheric transport and diffusion of certain chemical systems. As a result, a significantly improved version of the model, called FEM3A, was delivered to ERDEC in 1988. During the past few years, two more major improvements have been developed and tested. They are: improved mass conservation for treating dispersion scenarios with large density variations, and the addition of an advanced turbulence submodel based on the k-{var_epsilon} transport equations. These enhancements have resulted in substantial improvements in the dispersion simulations of heavy-gases and can greatly extend the range of applicability of the model, including the ability to treat problems with large density variations and dispersion scenarios of much greater complexities. Documented in this report are the new features and some of the improvements obtained with the new model.

  4. Pellet imaging techniques on ASDEX

    SciTech Connect

    Wurden, G.A. ); Buechl, K.; Hofmann, J.; Lang, R.; Loch, R.; Rudyj, A.; Sandmann, W. )

    1990-01-01

    As part of a USDOE/ASDEX collaboration, a detailed examination of pellet ablation in ASDEX with a variety of diagnostics has allowed a better understanding of a number of features of hydrogen ice pellet ablation in a plasma. In particular, fast gated photos with an intensified Xybion CCD video camera allow in-situ velocity measurements of the pellet as it penetrates the plasma. With time resolution of typically 100 nanoseconds and exposures every 50 microseconds, the evolution of each pellet in a multi-pellet ASDEX tokamak plasma discharge can be followed. When the pellet cloud track has striations, the light intensity profile through the cloud is hollow (dark near the pellet), whereas at the beginning or near the end of the pellet trajectory the track is typically smooth (without striations) and has a gaussian-peaked light emission profile. New, single pellet Stark broadened D{sub {alpha}}D{sub {beta}}, and D{sub {gamma}} spectra, obtained with a tangentially viewing scanning mirror/spectrometer with Reticon array readout, are consistent with cloud densities of 2 {times} 10{sup 17}cm{sup {minus}3} or higher in the regions of strongest light emission. A spatially resolved array of D{sub {alpha}} detectors shows that the light variations during the pellet ablation are not caused solely by a modulation of the incoming energy flux as the pellet crosses rational q-surfaces, but instead are a result of a dynamic, non-stationary, ablation process. 20 refs., 4 figs.

  5. Coronagraphic Upgrades at the VLT/NaCo: 4-Micron APP Enhanced Spectroscopy?

    NASA Astrophysics Data System (ADS)

    Girard, Julien H. V.; Janson, Markus; Quanz, Sascha P.; Kenworthy, Matthew A.; Meyer, Michael R.; Kasper, Markus; Lenzen, Rainer; Wehmeier, Udo

    2010-10-01

    We present coronagraphic upgrades that took place in the past months on NaCo, the versatile high contrast imager/spectrograph currently operated at the Very Large Telescope (VLT). A review of the current high contrast techniques available on NACO is presented as well as potential upgrades. As strong emphasis is made on the advantage of using the 3-5 μm domain for achieving outstanding detectability and characterization of hot jupiters. The new Apodizing Phase Plate (APP) coronagraph successfully commissioned earlier in 2010 is introduced. Preliminary tests on APP enhanced spectroscopy are shown. This unique capability could allow to reach unprecedented science goals: directly detect molecular features (CH4, CO, etc.) of the atmosphere of gaseous exoplanets at relatively low inner working angles (0.2 to 0.8").

  6. A CONCEPTUAL 3-GEV LANSCE LINAC UPGRADE FOR ENHANCED PROTON RADIOGRAPHY

    SciTech Connect

    Garnett, Robert W; Rybarcyk, Lawrence J.; Merrill, Frank E.; O'Hara, James F.; Rees, Daniel E.; Walstrom, Peter L.

    2012-05-14

    A conceptual design of a 3-GeV linac upgrade that would enable enhanced proton radiography at the Los Alamos Neutron Science Center (LANSCE) is presented. The upgrade is based on the use of superconducting accelerating cavities to increase the present LANSCE linac output energy from 800 MeV to 3 GeV. The LANSCE linac currently provides negative hydrogen ion (H{sup -}) and proton (H{sup +}) beams to several user facilities that support Isotope Production, NNSA Stockpile Stewardship, and Basic Energy Science programs. Required changes to the front-end, the accelerating structures, and to the RF systems to meet the new performance goals, and changes to the existing beam switchyard to maintain operations for a robust user program are also described.

  7. Viewgraphs presented at the ASDEX/DOE workshop on disruptions in divertor tokamaks

    SciTech Connect

    Granetz, R.; Gruber, O.; Zohm, H.

    1994-09-01

    The emphasis of this year`s ASDEX/DOE workshop was on disruptions in diverted tokamaks. The meeting was held here at MIT on 14--15 March. It is particularly appropriate that MIT hosted the workshop this year, since Alcator C-Mod had just recently completed its very first run campaign, and disruptions are one of the key areas of research in our program. There were a total of 14 speakers, with participants from IPP (Garching), CRPP (Lausanne), Culham, General Atomics, PPPL, Sandia, ORNL, the ITER JCT, and MIT. The subjects addressed included statistical analysis of disruption probabilities in ASDEX, modelling of the vertical axisymmetric plasma motion in DIII-D, impact of disruptions on the design of the ITER divertors, modelling of runaway electrons, and TSC calculations of disruption-induced currents and forces in TPX, etc. One item of particular interest to us was the experimental correlation of halo current magnitude with plasma current on ASDEX-Upgrade. The data indicates at least a linear, and possibly even a quadractic dependence. This has important implications for Alcator C-Mod, since it would predict halo currents of order 1 MA or more at full performance. At the conclusion of the talks, an informal discussion of disruption databases was held, primarily for the purpose of helping us develop a useful one for C-Mod.

  8. EPIC Computer Upgrade

    NASA Video Gallery

    Expedition 30 Commander Dan Burbank and Flight Engineer Don Pettit work on installing hardware for the Enhanced Processor and Integrated Communications (EPIC) upgrade of the International Space Sta...

  9. Pellet imaging techniques in the ASDEX tokamak

    SciTech Connect

    Wurden, G.A. ); Buechl, K.; Hofmann, J.; Lang, R.; Loch, R.; Rudyj, A.; Sandmann, W. )

    1990-11-01

    As part of a USDOE/ASDEX collaboration, a detailed examination of pellet ablation in ASDEX with a variety of diagnostics has allowed a better understanding of a number of features of hydrogen ice pellet ablation in a plasma. In particular, fast-gated photos with an intensified Xybion CCD video camera allow {ital in} {ital situ} velocity measurements of the pellet as it penetrates the plasma. With time resolution of typically 100 ns and exposures every 50 {mu}s, the evolution of each pellet in a multipellet ASDEX tokamak plasma discharge can be followed. When the pellet cloud track has striations, the light intensity profile through the cloud is hollow (dark near the pellet), whereas at the beginning or near the end of the pellet trajectory the track is typically smooth (without striations) and has a gaussian-peaked light emission profile. New, single pellet Stark broadened {ital D}{sub {alpha}}, {ital D}{sub {beta}}, and {ital D}{sub {gamma}} spectra, obtained with a tangentially viewing scanning mirror/spectrometer with Reticon array readout, are consistent with cloud densities of 2{times}10{sup 17} cm{sup {minus}3} or higher in the regions of strongest light emission. A spatially resolved array of {ital D}{sub {alpha}} detectors shows that the light variations during the pellet ablation are not caused solely by a modulation of the incoming energy flux as the pellet crosses rational {ital q} surfaces, but instead are a result of dynamic, nonstationary, ablation process.

  10. Captain upgrade CRM training: A new focus for enhanced flight operations

    NASA Technical Reports Server (NTRS)

    Taggart, William R.

    1993-01-01

    Crew Resource Management (CRM) research has resulted in numerous payoffs of applied applications in flight training and standardization of air carrier flight operations. This paper describes one example of how basic research into human factors and crew performance was used to create a specific training intervention for upgrading new captains for a major United States air carrier. The basis for the training is examined along with some of the specific training methods used, and several unexpeced results.

  11. The upgraded cold neutron triple-axis spectrometer FLEXX - enhanced capabilities by new instrumental options

    NASA Astrophysics Data System (ADS)

    Habicht, Klaus; Lucía Quintero-Castro, Diana; Toft-Petersen, Rasmus; Kure, Mathias; Mäde, Lucas; Groitl, Felix; Le, Manh Duc

    2015-01-01

    The upgrade of the cold neutron triple axis spectrometer FLEXX, a work-horse instrument for inelastic neutron scattering matching the sample environment capabilities at Helmholtz-Zentrum Berlin, has been successfully accomplished. Experiments confirmed an order of magnitude gain in flux now allowing for intensity demanding options to be fully exploited at FLEXX. In this article, we describe the layout and design of two newly available FLEXX instrument options in detail. The new Heusler analyzer gives an increase of the detected polarized neutron flux due to its superior focusing properties, significantly improving the feasibility of future polarized and neutron resonance spin echo experiments. The MultiFLEXX option provides simultaneous access to large regions in wavevector and energy space for inelastic excitations thus adding mapping capabilities to the spectrometer.

  12. SOVENT BASED ENHANCED OIL RECOVERY FOR IN-SITU UPGRADING OF HEAVY OIL SANDS

    SciTech Connect

    Munroe, Norman

    2009-01-30

    With the depletion of conventional crude oil reserves in the world, heavy oil and bitumen resources have great potential to meet the future demand for petroleum products. However, oil recovery from heavy oil and bitumen reservoirs is much more difficult than that from conventional oil reservoirs. This is mainly because heavy oil or bitumen is partially or completely immobile under reservoir conditions due to its extremely high viscosity, which creates special production challenges. In order to overcome these challenges significant efforts were devoted by Applied Research Center (ARC) at Florida International University and The Center for Energy Economics (CEE) at the University of Texas. A simplified model was developed to assess the density of the upgraded crude depending on the ratio of solvent mass to crude oil mass, temperature, pressure and the properties of the crude oil. The simplified model incorporated the interaction dynamics into a homogeneous, porous heavy oil reservoir to simulate the dispersion and concentration of injected CO2. The model also incorporated the characteristic of a highly varying CO2 density near the critical point. Since the major challenge in heavy oil recovery is its high viscosity, most researchers have focused their investigations on this parameter in the laboratory as well as in the field resulting in disparaging results. This was attributed to oil being a complex poly-disperse blend of light and heavy paraffins, aromatics, resins and asphaltenes, which have diverse behaviors at reservoir temperature and pressures. The situation is exacerbated by a dearth of experimental data on gas diffusion coefficients in heavy oils due to the tedious nature of diffusivity measurements. Ultimately, the viscosity and thus oil recovery is regulated by pressure and its effect on the diffusion coefficient and oil swelling factors. The generation of a new phase within the crude and the differences in mobility between the new crude matrix and the

  13. Fueling efficiency of gas puffing in ASDEX

    NASA Astrophysics Data System (ADS)

    Mayer, H.-M.; Wagner, F.; Becker, G.; Behringer, K.; Campbell, D.; Eberhagen, A.; Engelhardt, W.; Fussman, G.; Gehre, O.; Gierke, G. v.; Glock, E.; Haas, G.; Huang, M.; Karger, F.; Keilhacker, M.; Klüber, O.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Schneider, F.; Siller, G.; Steuer, K.-H.; Venus, G.

    1982-12-01

    The fueling efficiency for gas puffing, i.e. the fraction of the external gas flux that is ionized inside the separatrix, is reduced in divertor discharges since part of it is ionized in the scrape-off layer and pumped off by the divertor. The fueling efficiency is determined by switching-off the gas feed during the stationary phase of a discharge and dividing the time derivative of the total number of particles inside the separatrix by the external gas flux. The determination of this time derivative must take into account profile changes. In ASDEX the fueling efficiency ranges from close to 1.0 for discharges with a stainless steel poloidal limiter and decreases to about 0.2 at high densities ( 6 × 10 13 cm -3 line average) for diverted discharges. These results are compared with estimates of the fueling efficiency which include molecular disintegration, plasma albedo for neutral atoms and imperfect wall reflection.

  14. Long-pulse suprathermal discharges in the ASDEX tokamak

    SciTech Connect

    Fussmann, G.; Campbell, D.; Eberhagen, A.; Engelhardt, W.; Karger, F.; Keilhacker, M.; Klueber, O.; Lackner, K.; Sesnic, S.; Wagner, F.; Behringer, K.; Gehre, O.; Gernhardt, J.; Glock, E.; Haas, G.; Kornherr, M.; Lisitano, G.; Mayer, H.M.; Meisel, D.; Mueller, R.; Murmann, H.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Ruhs, N.; Schneider, F.; Siller, G.; Steuer, K.

    1981-10-05

    Use of the ASDEX divertor permits the production of stable low-density discharges (n/sub e/> or approx. =10/sup 12/ cm/sup -3/) with extremely low resistivity lasting for more than 10 s. While the distribution functions of electrons and ions show suprathermal tails, runaway electrons in the megaelectronvolt range are found to disappear with decreasing density. There are indications that in these discharges the energy confinement is improved compared with ALCATOR scaling.

  15. Improved confinement with counter neutral injection into ASDEX

    SciTech Connect

    Gehre, O.; Gruber, O.; Murmann, H.D.; Roberts, D.E.; Wagner, F.; Bomba, B.; Eberhagen, A.; Fahrbach, H.U.; Fussmann, G.; Gernhardt, J.; and others

    1988-04-11

    Counter injection into ASDEX leads to good particle, momentum, and also energy confinement with tau/sub E/ = 80 ms at 1 MW (43 ms for co-injection). The improved confinement develops gradually during the heating phase and correlates with a simultaneous peaking of the density profile. The ion heat transport has to be reduced for a consistent transport analysis, in agreement with theoretical expectations. The sawtooth instability flattens the density profile and transiently reduces the energy content.

  16. Pellet imaging techniques in the ASDEX tokamak (abstract)

    SciTech Connect

    Wurden, G.A. ); Buechl, K.; Hofmann, J.; Lang, R.; Loch, R.; Rudyj, A.; Sandmann, W. )

    1990-10-01

    As part of a USDOE/ASDEX collaboration, a detailed examination of pellet ablation in ASDEX with a variety of diagnostics has allowed a better understanding of a number of features of hydrogen ice pellet ablation in a plasma. In particular, fast-gated photos with an intensified Xybion CCD video camera allow {ital in} {ital situ} velocity measurements of the pellet as it penetrates the plasma. With time resolution of typically 100 ns and exposures every 50 {mu}s, the evolution of each pellet in a multipellet ASDEX tokamak plasma discharge can be followed. When the pellet cloud track has striations, the light intensity profile through the cloud is hollow (dark near the pellet), whereas at the beginning or near the end of the pellet trajectory the track is typically smooth (without striations) and has a gaussian-peaked light emission profile. New, single pellet Stark broadened {ital D}{sub {alpha}}, {ital D}{sub {beta}}, and {ital D}{sub {gamma}} spectra, obtained with a tangentially viewing scanning mirror/spectrometer with Reticon array readout, are consistent with cloud densities of 2{times}10{sup 17} cm{sup {minus}3} or higher in the regions of strongest light emission. A spatially resolved array of {ital D}{sub {alpha}} detectors shows that the light variations during the pellet ablation are not caused solely by a modulation of the incoming energy flux as the pellet crosses rational {ital q} surfaces, but instead are a result of dynamic, nonstationary, ablation process.

  17. Ion cyclotron resonance heating in the divertor tokamak ASDEX

    SciTech Connect

    Steinmetz, K.; Wesner, F.; Niedermeyer, H.; Becker, G.; Braun, F.; Eberhagen, A.; Fussmann, G.; Gehre, O.; Gernhardt, J.; v. Gierke, G.

    1986-05-01

    The main topics of ICRF investigations in ASDEX are the influence of the divertor on impurity production and transport in ICRH heated discharges, and the heating efficiency and plasma confinement in various scenarios (minority and harmonics regimes). The first experiments were conducted in November 1984 at 67 MHz, corresponding to second harmonic heating of a hydrogen plasma at B/sub 0/ = 2.2 T. A transmitted power of 2.5 MW has been reached so far, the total capability being 3 MW. A linear increase of the central electron and ion temperature with the rf power is observed in Ohmically preheated plasmas (..delta..T/sub e/approx.280 eV, ..delta..T/sub i/approx.500 eV, ..delta..W/sub p/approx.17 kJ at a power of 1.2 MW coupled to the plasma and n-bar/sub e/ = 3.5 x 10/sup 13/ cm/sup -3/). The total radiation increases linearly with the power, too, and the ratio P/sub rad//P/sub tot/approx.0.35 stays approximately constant. However, first investigations indicate that with a divertor, ICRF operation is also accompanied by a significant increase in impurity production. The presence of neutral beam injection in addition to ICRH clearly enhances the absorption of the wave energy from about 50% to up to 90% with respect to the coupled power. With neutral beam injection (P/sub NI/< or =3.5 MW) the increment of the plasma energy content due to ICRH (P/sub rf/< or =2 MW) is found to be almost twice as large as in case OH+ICRH. Global heating efficiencies of up to 3 x 10/sup 13/ eV/kW cm/sup 3/ compare quite well with other ICRH experiments. First observations indicate a degradation of plasma confinement with ICRH to values in between L-type and OH confinement.

  18. Environmental assessment: Solid waste retrieval complex, enhanced radioactive and mixed waste storage facility, infrastructure upgrades, and central waste support complex, Hanford Site, Richland, Washington

    SciTech Connect

    1995-09-01

    The U.S. Department of Energy (DOE) needs to take action to: retrieve transuranic (TRU) waste because interim storage waste containers have exceeded their 20-year design life and could fail causing a radioactive release to the environment provide storage capacity for retrieved and newly generated TRU, Greater-than-Category 3 (GTC3), and mixed waste before treatment and/or shipment to the Waste Isolation Pilot Project (WIPP); and upgrade the infrastructure network in the 200 West Area to enhance operational efficiencies and reduce the cost of operating the Solid Waste Operations Complex. This proposed action would initiate the retrieval activities (Retrieval) from Trench 4C-T04 in the 200 West Area including the construction of support facilities necessary to carry out the retrieval operations. In addition, the proposed action includes the construction and operation of a facility (Enhanced Radioactive Mixed Waste Storage Facility) in the 200 West Area to store newly generated and the retrieved waste while it awaits shipment to a final disposal site. Also, Infrastructure Upgrades and a Central Waste Support Complex are necessary to support the Hanford Site`s centralized waste management area in the 200 West Area. The proposed action also includes mitigation for the loss of priority shrub-steppe habitat resulting from construction. The estimated total cost of the proposed action is $66 million.

  19. ISS Update: Computer Upgrade on Station

    NASA Video Gallery

    NASA Public Affairs Officer Brandi Dean interviews Gary Cox, EPIC Project Manager, about EPIC (Enhanced Processor and Integrated Communications), the computer upgrade program for the International ...

  20. High frequency magnetic fluctuations correlated with the inter-ELM pedestal evolution in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Laggner, F. M.; Wolfrum, E.; Cavedon, M.; Mink, F.; Viezzer, E.; Dunne, M. G.; Manz, P.; Doerk, H.; Birkenmeier, G.; Fischer, R.; Fietz, S.; Maraschek, M.; Willensdorfer, M.; Aumayr, F.; the EUROfusion MST1 Team; the ASDEX Upgrade Team

    2016-06-01

    In order to understand the mechanisms that determine the structure of the high confinement mode (H-mode) pedestal, the evolution of the plasma edge electron density and temperature profiles between edge localised modes (ELMs) is investigated. The onset of radial magnetic fluctuations with frequencies above 200 kHz is found to correlate with the stagnation of the electron temperature pedestal gradient. During the presence of these magnetic fluctuations the gradients of the edge electron density and temperature are clamped and stable against the ELM onset. The detected magnetic fluctuation frequency is analysed for a variety of plasma discharges with different electron pressure pedestals. It is shown that the magnetic fluctuation frequency scales with the neoclassically estimated \\text{E} × \\text{B} velocity at the plasma edge. This points to a location of the underlying instability in the gradient region. Furthermore, the magnetic signature of these fluctuations indicates a global mode structure with toroidal mode numbers of approximately 10. The fluctuations are also observed on the high field side with significant amplitude, indicating a mode structure that is symmetric on the low field side and high field side. The associated fluctuations in the current on the high field side might be attributed to either a strong peeling part or the presence of non-adiabatic electron response.

  1. Convective and Diffusive Energetic Particle Losses Induced by Shear Alfven Waves in the ASDEX Upgrade Tokamak

    SciTech Connect

    Garcia-Munoz, M.; Hicks, N.; Bilato, R.; Bobkov, V.; Bruedgam, M.; Fahrbach, H.-U.; Igochine, V.; Maraschek, M.; Sassenberg, K.; Voornveld, R. van; Classen, I. G. J.; Jaemsae, S.

    2010-05-07

    We present here the first phase-space characterization of convective and diffusive energetic particle losses induced by shear Alfven waves in a magnetically confined fusion plasma. While single toroidal Alfven eigenmodes (TAE) and Alfven cascades (AC) eject resonant fast ions in a convective process, an overlapping of AC and TAE spatial structures leads to a large fast-ion diffusion and loss. Diffusive fast-ion losses have been observed with a single TAE above a certain threshold in the fluctuation amplitude.

  2. Predictive modelling of the impact of a radiative divertor on pedestal confinement on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Dunne, Mike; Potzel, Steffen; Wischmeier, Marco; Wolfrum, Elisabeth; Frassinetti, Lorenzo; Reimold, Felix; Eurofusion Mst1 Team; ASDEX Upgrade Team

    2015-11-01

    In future devices, tailoring of the edge density profile and radiation profile for power exhaust control via a deuterium gas puff and extrinsic impurity seeding will be necessary. It has been observed on present day machines that high D fuelling can reduce the plasma stored energy while adding impurity seeding can act to improve confinement by up to 40%. This study presents a combination of observations and modelling completed on AUG with the aim of determining the mechanisms behind the confinement degradation with a gas puff and improvement with impurity seeding. In particular, predictive modelling, based on the EPED pedestal model, has been extensively used. Alterations of the temperature and density at the separatrix are found to have large impacts on pedestal stability. Measured changes in divertor properties are used to inform the direction and magnitude of these alterations, with experimentally relevant confinement changes being recovered via pressure profile shifts. http://www.euro-fusionscipub.org/mst1

  3. Advanced ECCD based NTM control in closed-loop operation at ASDEX Upgrade (AUG)

    NASA Astrophysics Data System (ADS)

    Reich, Matthias; Barrera-Orte, Laura; Behler, Karl; Bock, Alexander; Giannone, Louis; Maraschek, Marc; Poli, Emanuele; Rapson, Chris; Stober, Jörg; Treutterer, Wolfgang

    2012-10-01

    In high performance plasmas, Neoclassical Tearing Modes (NTMs) are regularly observed at reactor-grade beta-values. They limit the achievable normalized beta, which is undesirable because fusion performance scales as beta squared. The method of choice for controlling and avoiding NTMs at AUG is the deposition of ECCD inside the magnetic island for stabilization in real-time (rt). Our approach to tackling such complex control problems using real-time diagnostics allows rigorous optimization of all subsystems. Recent progress in rt-equilibrium reconstruction (< 3.5 ms), rt-localization of NTMs (< 8 ms) and rt beam tracing (< 25 ms) allows closed-loop feedback operation using multiple movable mirrors as the ECCD deposition actuator. The rt-equilibrium uses function parametrization or a fast Grad-Shafranov solver with an option to include rt-MSE measurements. The island localization is based on a correlation of ECE and filtered Mirnov signals. The rt beam-tracing module provides deposition locations and their derivative versus actuator position of multiple gyrotrons. The ``MHD controller'' finally drives the actuators. Results utilizing closed-loop operation with multiple gyrotrons and their effect on NTMs are shown.

  4. Site-specific economic and ecological analysis of enhanced production, upgrade and feed-in of biomethane from organic wastes.

    PubMed

    Lindorfer, J; Schwarz, M M

    2013-01-01

    The present study analyses the cost structure and ecological performance of biomethane production and feed-in from organic wastes and manure in a site-specific approach for Upper Austria. The theoretically available quantities of biowaste and manure can feed representative biogas plant capacities resulting in relatively high biomethane full costs in the natural gas grid of at least 9.0 €-cents/kWh, which shows strong economies of scale when feed-in flows of methane from 30 to 120 Nm(3)/h are considered. From the ecological point of view small plant capacities are to be preferred since the environmental effect, i.e. the global warming potential (up to -22% of CO(2eq)), is lower in comparison to higher capacities as a consequence of reduced transport in the evaluated scenarios. To enforce the combined energetic use of the biowaste fraction, co-operation between compost facility, gas grid and biogas plant operators is necessary to use existing infrastructure, logistics and knowledge to promote the production, upgrade and feed-in of biomethane from biowastes at attractive locations in Upper Austria and in the whole of Europe. PMID:23202576

  5. HVCM Topology Enhancements to Support a Power Upgrade Required by a Second Target Station (STS) at SNS

    SciTech Connect

    Solley, Dennis J; Anderson, David E; Patel, Gunjan P; Peplov, Vladimir V; Saethre, Robert B; Wezensky, Mark W

    2012-01-01

    This paper discusses the topology used in the HVCMs at SNS to process power for both the cold and warm linac sections of the klystron gallery in support of extended operations at the megawatt level. In anticipation of a second target station and higher anticipated power levels, an enhancement to the present topology is being investigated. SPICE circuit simulations and preliminary experimental data will be presented.

  6. Upgrading food wastes by means of bromelain and papain to enhance growth and immunity of grass carp (Ctenopharyngodon idella).

    PubMed

    Choi, W M; Lam, C L; Mo, W Y; Wong, M H

    2016-04-01

    The fast growing of global aquaculture industry accompanied with increasing pressure on the supply and price of traditional feed materials (e.g., fish meal and soy bean meal). This circumstance has urged the need to search alternative sources of feed stuff. Food waste was used as feed stuff in rearing fish which possess substantial protein and lipid. Grass carp are major species reared in Hong Kong with lower nutritional requirements; it is also an ideal species for investigating the feasibility of using food waste as fish feeds for local aquaculture industry. The growth and immunity, reflected by total protein, total immunologlobulin (IgI), and nitroblue tetrazolium (NBT) activity of grass carp blood, were depressed when feeding with food waste feeds without enzymes. However, the supplementation of bromelain and papain in fish feed enhanced the efficient use of food waste by grass carp, which in turn improved the fish immunity. The present results indicated that the addition of those enzymes could enhance the feed utilization by fish and hematological parameters of grass carp, and the improvement on growth and immunity superior to the control (commercial feed) was observed with the addition of bromelain and papain supplement. Addition of 1 and 2 % mixture of bromelain and papain could significantly enhance the lipid utilization in grass carp. PMID:26092357

  7. Improved comfinement in high-density ohmic discharges in ASDEX

    SciTech Connect

    Soeldner, F.X.; Mueller, E.R.; Wagner, F.; Bosch, H.S.; Eberhagen, A.; Fahrbach, H.U.; Fussmann, G.; Gehre, O.; Gentle, K.; Gernhardt, J.; and others

    1988-08-29

    The unsaturated linear rise of the energy confinement time with density, tau/sub E/approx.n-bar/sub e/, up to the density limit is recovered in Ohmically heated, discharges in ASDEX. Improvement of a factor of 2 is reached with tau/sub E/approx. =150 ms at n-bar/sub e/ = 5 x 10/sup 13/ cm/sup -3/. The improved state is characterized by peaked density profiles. The ion heat diffusivity decreases to the neoclassical value. The parameter eta/sub i/ = L/sub =//L/sub =/, governing the onset of ion-temperature-gradient modes, falls to the stability threshold. The improvement in confinement might therefore be attributed to the stabilization of eta/sub i/ modes.

  8. The upgraded DØ detector

    NASA Astrophysics Data System (ADS)

    Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, D. L.; Adams, M.; Adams, T.; Agelou, M.; Agram, J.-L.; Ahmed, S. N.; Ahn, S. H.; Ahsan, M.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Anastasoaie, M.; Andeen, T.; Anderson, J. T.; Anderson, S.; Andrieu, B.; Angstadt, R.; Anosov, V.; Arnoud, Y.; Arov, M.; Askew, A.; Åsman, B.; Assis Jesus, A. C. S.; Atramentov, O.; Autermann, C.; Avila, C.; Babukhadia, L.; Bacon, T. C.; Badaud, F.; Baden, A.; Baffioni, S.; Bagby, L.; Baldin, B.; Balm, P. W.; Banerjee, P.; Banerjee, S.; Barberis, E.; Bardon, O.; Barg, W.; Bargassa, P.; Baringer, P.; Barnes, C.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bhattacharjee, M.; Baturitsky, M. A.; Bauer, D.; Bean, A.; Baumbaugh, B.; Beauceron, S.; Begalli, M.; Beaudette, F.; Begel, M.; Bellavance, A.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Besson, A.; Beuselinck, R.; Beutel, D.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Binder, M.; Biscarat, C.; Bishoff, A.; Black, K. M.; Blackler, I.; Blazey, G.; Blekman, F.; Blessing, S.; Bloch, D.; Blumenschein, U.; Bockenthien, E.; Bodyagin, V.; Boehnlein, A.; Boeriu, O.; Bolton, T. A.; Bonamy, P.; Bonifas, D.; Borcherding, F.; Borissov, G.; Bos, K.; Bose, T.; Boswell, C.; Bowden, M.; Brandt, A.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchanan, N. J.; Buchholz, D.; Buehler, M.; Buescher, V.; Burdin, S.; Burke, S.; Burnett, T. H.; Busato, E.; Buszello, C. P.; Butler, D.; Butler, J. M.; Cammin, J.; Caron, S.; Bystricky, J.; Canal, L.; Canelli, F.; Carvalho, W.; Casey, B. C. K.; Casey, D.; Cason, N. M.; Castilla-Valdez, H.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapin, D.; Charles, F.; Cheu, E.; Chevalier, L.; Chi, E.; Chiche, R.; Cho, D. K.; Choate, R.; Choi, S.; Choudhary, B.; Chopra, S.; Christenson, J. H.; Christiansen, T.; Christofek, L.; Churin, I.; Cisko, G.; Claes, D.; Clark, A. R.; Clément, B.; Clément, C.; Coadou, Y.; Colling, D. J.; Coney, L.; Connolly, B.; Cooke, M.; Cooper, W. E.; Coppage, D.; Corcoran, M.; Coss, J.; Cothenet, A.; Cousinou, M.-C.; Cox, B.; Crépé-Renaudin, S.; Cristetiu, M.; Cummings, M. A. C.; Cutts, D.; da Motta, H.; Das, M.; Davies, B.; Davies, G.; Davis, G. A.; Davis, W.; De, K.; de Jong, P.; de Jong, S. J.; De La Cruz-Burelo, E.; De La Taille, C.; De Oliveira Martins, C.; Dean, S.; Degenhardt, J. D.; Déliot, F.; Delsart, P. A.; Del Signore, K.; DeMaat, R.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; Doets, M.; Doidge, M.; Dong, H.; Doulas, S.; Dudko, L. V.; Duflot, L.; Dugad, S. R.; Duperrin, A.; Dvornikov, O.; Dyer, J.; Dyshkant, A.; Eads, M.; Edmunds, D.; Edwards, T.; Ellison, J.; Elmsheuser, J.; Eltzroth, J. T.; Elvira, V. D.; Eno, S.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, D.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Fagan, J.; Fast, J.; Fatakia, S. N.; Fein, D.; Feligioni, L.; Ferapontov, A. V.; Ferbel, T.; Ferreira, M. J.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fleck, I.; Fitzpatrick, T.; Flattum, E.; Fleuret, F.; Flores, R.; Foglesong, J.; Fortner, M.; Fox, H.; Franklin, C.; Freeman, W.; Fu, S.; Fuess, S.; Gadfort, T.; Galea, C. F.; Gallas, E.; Galyaev, E.; Gao, M.; Garcia, C.; Garcia-Bellido, A.; Gardner, J.; Gavrilov, V.; Gay, A.; Gay, P.; Gelé, D.; Gelhaus, R.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gillberg, D.; Geurkov, G.; Ginther, G.; Gobbi, B.; Goldmann, K.; Golling, T.; Gollub, N.; Golovtsov, V.; Gómez, B.; Gomez, G.; Gomez, R.; Goodwin, R.; Gornushkin, Y.; Gounder, K.; Goussiou, A.; Graham, D.; Graham, G.; Grannis, P. D.; Gray, K.; Greder, S.; Green, D. R.; Green, J.; Green, J. A.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Groer, L.; Grünendahl, S.; Grünewald, M. W.; Gu, W.; Guglielmo, J.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hadley, N. J.; Haggard, E.; Haggerty, H.; Hagopian, S.; Hall, I.; Hall, R. E.; Han, C.; Han, L.; Hance, R.; Hanagaki, K.; Hanlet, P.; Hansen, S.; Harder, K.; Harel, A.; Harrington, R.; Hauptman, J. M.; Hauser, R.; Hays, C.; Hays, J.; Hazen, E.; Hebbeker, T.; Hebert, C.; Hedin, D.; Heinmiller, J. M.; Heinson, A. P.; Heintz, U.; Hensel, C.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Hong, S. J.; Hooper, R.; Hou, S.; Houben, P.; Hu, Y.; Huang, J.; Huang, Y.; Hynek, V.; Huffman, D.; Iashvili, I.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jacquier, Y.; Jaffré, M.; Jain, S.; Jain, V.; Jakobs, K.; Jayanti, R.; Jenkins, A.; Jesik, R.; Jiang, Y.; Johns, K.; Johnson, M.; Johnson, P.; Jonckheere, A.; Jonsson, P.; Jöstlein, H.; Jouravlev, N.; Juarez, M.; Juste, A.; Kaan, A. P.; Kado, M. M.; Käfer, D.; Kahl, W.; Kahn, S.; Kajfasz, E.

    2006-09-01

    The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.

  9. Impurity production and plasma performance in ASDEX discharges with ohmic and auxiliary heating

    NASA Astrophysics Data System (ADS)

    Fussmann, G.; ASDEX Team; NI Team; Icrh Team; Hofmann, J.; Janeschitz, G.; Lenoci, M.; Mast, F.; McCormick, K.; Murmann, H.; Poschenrieder, W.; Roth, J.; Setzensack, C.; Staudenmaier, G.; Steuer, K.-H.; Taglauer, E.; Verbeek, H.; Wagner, F.; Becker, G.; Bosch, H. S.; Brocken, H.; Eberhagen, A.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Clock, E.; Gruber, O.; Haas, G.; Izvozchikov, A.; Karger, F.; Kaufmann, M.; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lisitano, G.; Mayer, H. M.; Meisel, D.; Mertens, V.; Müller, E. R.; Neuhauser, J.; Niedermeyer, H.; Noterdaeme, J.-M.; Pietrzyk, Z. A.; Rapp, H.; Riedler, H.; Röhr, H.; Ryter, F.; Schneider, F.; Siller, G.; Smeulders, P.; Söldner, F. X.; Speth, E.; Steinmetz, K.; Tsois, N.; Ugniewski, S.; Vollmer, O.; Wesner, F.; Zasche, D.

    1987-02-01

    A review is given on investigations in the ASDEX Tokamak on impurities in ohmically, NI and ICRH heated plasmas. For ohmic discharges in H 2 and D 2 it is found that iron release from the wall can be explained by sputtering due to neutral charge exchange (CX) atoms. In the case of He, however, significant contributions caused by ion sputtering are inferred. Comparing discharges with C limiters in He and D 2 suggests that in the case of hydrogen chemical processes are involved in C sputtering. By means of wall carbonization the concentrations of metal ions in the plasma could be substantially reduced. This achievement is of particular importance for NI counter-injection and ICRH, where under non-carbonized conditions severe impurity problems occur. We studied impurity confinement in the case of various heating scenarios by means of the laser injection technique. The poorest confinement is found for the L-phase of NI. Metal injection into the high confinement H-phase generally causes temporary suppression of the edge localized modes (ELM's). With respect to ICRH we conclude that enhanced wall erosion — probably due to the production of high energy ions in the boundary — together with a slightly increased impurity confinement is the dominant reason for the increase of the metallic concentrations. Impurity sputtering as an alternative strong erosion process was experimentally ruled out.

  10. Vacuum upgrade and enhanced performances of the double imaging electron/ion coincidence end-station at the vacuum ultraviolet beamline DESIRS

    NASA Astrophysics Data System (ADS)

    Tang, Xiaofeng; Garcia, Gustavo A.; Gil, Jean-François; Nahon, Laurent

    2015-12-01

    We report here the recent upgrade of the SAPHIRS permanent photoionization end-station at the DESIRS vacuum ultraviolet beamline of synchrotron SOLEIL, whose performances have been enhanced by installing an additional double-skimmer differential chamber. The smaller molecular beam profile obtained at the interaction region has increased the mass resolution of the double imaging photoelectron photoion coincidence (i2PEPICO) spectrometer, DELICIOUS III, installed in the photoionization chamber of the SAPHIRS endstation, by a factor of two, to M/ΔM ˜ 1700 (FWHM). The electron kinetic energy resolution offered by the velocity map imaging (VMI) part of the spectrometer has been improved down to 2.8% (ΔE/E) as we show on the N2 photoionization case in the double skimmer configuration. As a representative example of the overall state-of-the-art i2PEPICO performances, experimental results of the dissociation of state-selected O2+ (B 2 ∑ g - , v+ = 0-6) molecular ions performed at the fixed photon energy of hν = 21.1 eV are presented.

  11. Vacuum upgrade and enhanced performances of the double imaging electron/ion coincidence end-station at the vacuum ultraviolet beamline DESIRS.

    PubMed

    Tang, Xiaofeng; Garcia, Gustavo A; Gil, Jean-François; Nahon, Laurent

    2015-12-01

    We report here the recent upgrade of the SAPHIRS permanent photoionization end-station at the DESIRS vacuum ultraviolet beamline of synchrotron SOLEIL, whose performances have been enhanced by installing an additional double-skimmer differential chamber. The smaller molecular beam profile obtained at the interaction region has increased the mass resolution of the double imaging photoelectron photoion coincidence (i(2)PEPICO) spectrometer, DELICIOUS III, installed in the photoionization chamber of the SAPHIRS endstation, by a factor of two, to M/ΔM ∼ 1700 (FWHM). The electron kinetic energy resolution offered by the velocity map imaging (VMI) part of the spectrometer has been improved down to 2.8% (ΔE/E) as we show on the N2 photoionization case in the double skimmer configuration. As a representative example of the overall state-of-the-art i(2)PEPICO performances, experimental results of the dissociation of state-selected O2(+)(B(2)∑(g)(-), v(+) = 0-6) molecular ions performed at the fixed photon energy of hν = 21.1 eV are presented. PMID:26724007

  12. Final Upgrading Report: The Vermont Experience.

    ERIC Educational Resources Information Center

    Mattson, Robert E.

    This report describes Vermont's experience with a program to upgrade the working poor and thus increase their total family income. Upgrading refers to enhancing one's job skills which ultimately will lead to increased earnings within one's given occupation. Employer cooperation was encouraged through use of on-site job facilities where supervised…

  13. The upgrade of the Inner Tracking System of ALICE

    NASA Astrophysics Data System (ADS)

    Siddhanta, Sabyasachi

    2014-11-01

    ALICE has devised a comprehensive upgrade strategy to enhance its physics capabilities and to exploit the LHC running conditions after the second long shutdown of the LHC scheduled in 2018-2019. Within this upgrade programme, the upgrade of the Inner Tracking System (ITS) forms an important part. The upgraded ITS will have a barrel geometry consisting of seven layers of Monolithic Active Pixel Sensors (MAPS) with high granularity, which would fulfil the material budget, readout and radiation hardness requirements for the upgrade. In this contribution, an overview of the upgraded ITS, its technology and performance studies are presented.

  14. Behaviour of the ASDEX pressure gauge at high neutral gas pressure and applications for ITER

    SciTech Connect

    Scarabosio, A.; Haas, G.

    2008-03-12

    The ASDEX Pressure Gauge is, at present, the main candidate for in-vessel neutral pressure measurement in ITER. Although the APG output is found to saturate at around 15 Pa, below the ITER requirement of 20 Pa. We show, here, that with small modifications of the gauge geometry and potentials settings we can achieve satisfactory behaviour up to 30 Pa at 6 T.

  15. Creation of second order magnetic barrier inside chaos created by NTMs in the ASDEX UG

    NASA Astrophysics Data System (ADS)

    Ali, Halima; Punjabi, Alkesh

    2012-10-01

    Understanding and stabilization of neoclassical tearing modes (NTM) in tokamaks is an important problem. For low temperature plasmas, tearing modes are believed to be mainly driven by current density gradient. For collisionless plasmas, even when plasma is stable to classical tearing modes, helical reduction in bootstrap current in O-point of an island can destabilize NTMs when an initial island is seeded by other global MHD instabilities or when microturbulence triggers the transition from a linear to nonlinear instability. The onset of NTMs leads to the most serious beta limit in ASDEX UG tokamak [O. Gubner et al 2005 NF 39 1321]. The important NTMs in the ASDDEX UG are (m,n)=(3,2)+(4,3)+(1,1). Realistic parameterization of these NTMs and the safety factor in ASDEX UG are given in [O. Dumbrajs et al 2005 POP 12 1107004]. We use a symplectic map in magnetic coordinates for the ASDEX UG to integrate field lines in presence of the NTMs. We add a second order control term [H. Ali and A. Punjabi 2007 PPCF 49 1565] to this ASDEX UG field line Hamiltonian to create an invariant magnetic surface inside the chaos generated by the NTMs. The relative strength, robustness, and resilience of this barrier are studied to ascertain the most desirable noble barrier in the ASDEX UG with NTMs. We present preliminary results of this work, and discuss its implications with regard to magnetic transport barriers for increasing strength of magnetic perturbations. This work is supported by the grants DE-FG02-01ER54624 and DE-FG02-04ER54793.

  16. The D0 Upgrade

    SciTech Connect

    Abachi, S.; D0 Collaboration

    1995-07-01

    In this paper we describe the approved DO Upgrade detector, and its physics capabilities. The DO Upgrade is under construction and will run during the next Fermilab collider running period in early 1999 (Run II). The upgrade is designed to work at the higher luminosities and shorter bunch spacings expected during this run. The major elements of t he upgrade are: a new tracking system with a silicon tracker, scintillating fiber tracker, a 2T solenoid, and a central preshower detector; new calorimeter electronics; new muon trigger and tracking detectors with new muon system electronics; a forward preshower detector; new trigger electronics and DAQ improvements to handle the higher rates.

  17. Hydrocarbonaceous material upgrading method

    SciTech Connect

    Brecher, Lee E.; Mones, Charles G.; Guffey, Frank D.

    2015-06-02

    A hydrocarbonaceous material upgrading method may involve a novel combination of heating, vaporizing and chemically reacting hydrocarbonaceous feedstock that is substantially unpumpable at pipeline conditions, and condensation of vapors yielded thereby, in order to upgrade that feedstock to a hydrocarbonaceous material condensate that meets crude oil pipeline specification.

  18. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    In this project we well evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated. (VC)

  19. The Upgraded D0 detector

    SciTech Connect

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, D.L.; Adams, M.; Adams, T.; Agelou, M.; Agram, J.-L.; Ahmed, S.N.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G.A.; Anastasoaie, M.; Andeen, T.; Anderson, J.T.; Anderson, S.; /Buenos Aires U. /Rio de Janeiro, CBPF /Sao Paulo, IFT /Alberta U. /Simon Fraser U. /York U., Canada /McGill U. /Beijing, Inst. High Energy Phys. /Hefei, CUST /Andes U., Bogota /Charles U. /Prague, Tech. U. /Prague, Inst. Phys. /San Francisco de Quito U. /Clermont-Ferrand U. /LPSC, Grenoble /Marseille, CPPM /Orsay, LAL /Paris U., VI-VII /DAPNIA, Saclay /Strasbourg, IReS

    2005-07-01

    The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to D0.

  20. Convective Transport Suppression in the Scrape-Off Layer Using Ion Cyclotron Resonance Heating on the ASDEX Upgrade Tokamak

    SciTech Connect

    Antar, G.; Assas, S.; Bobkov, V.; Noterdaeme, J.-M.; Wolfrum, E.; Herrmann, A.; Rohde, V.

    2010-10-15

    Turbulence properties in the scrape-off layer (SOL) in the presence of ion cyclotron frequency heating (ICRH) are compared to instances where it is absent. The discharges are all in a high-confinement mode (H-mode) regime. During ICRH, the SOL plasma density increases whereas turbulence large-scale and convective structures are shown to be suppressed. The probability distribution function is thus recorded to be closer to a Gaussian, and a net decrease in the low-frequency density fluctuations is reflected in the power spectra. Consequently, the level of turbulent fluctuations decreases significantly. Turbulence suppression is also reported during edge localized modes (ELMs) where both the ELMs-induced transport and duration are strongly affected. The increase of neutrals by gas puffing did not alter this behavior. We deduce that ICRH can be used as to suppress convective transport and reduce the ELM's amplitude.

  1. Manufacturing and high heat flux loading of tungsten coatings on fine grain graphite for the ASDEX-upgrade divertor

    NASA Astrophysics Data System (ADS)

    Deschka, S.; García-Rosales, C.; Hohenauer, W.; Duwe, R.; Gauthier, E.; Linke, J.; Lochter, M.; Malléner, W.; Plöchl, L.; Rödhammer, P.; Salito, A.

    1996-10-01

    Fine grain graphite tiles coated with tungsten layers by plasma spray (PS, thickness 100-550 μm) and physical vapour deposition (PVD, 30-200 μm), respectively, were subjected to thermal loads up to 17 MW/m 2 and 2 s pulse duration. The damage limit was evaluated by increasing the heat flux and the pulse length stepwise. The results proved that PS coatings are capable of withstanding heat loads up to 15 MW/m 2 at 2 s pulse length without any structural changes, and cyclic loading with 1000 cycles at 10 MW/m 2. The highly dense PVD coatings suffered damage by crack formation at slightly lower heat loads, and thin PVD layers failed under cyclic loading with 1000 cycles at 10 MW/m 2 due to thermal fatigue and melting. The good performance of PS coatings is related to their porosity, which provides a crack arresting mechanism, and to their mechanical strength, depending on the density of the PS layer.

  2. Convective and diffusive energetic particle losses induced by shear Alfvén waves in the ASDEX upgrade tokamak.

    PubMed

    García-Muñoz, M; Hicks, N; van Voornveld, R; Classen, I G J; Bilato, R; Bobkov, V; Bruedgam, M; Fahrbach, H-U; Igochine, V; Jaemsae, S; Maraschek, M; Sassenberg, K

    2010-05-01

    We present here the first phase-space characterization of convective and diffusive energetic particle losses induced by shear Alfvén waves in a magnetically confined fusion plasma. While single toroidal Alfvén eigenmodes (TAE) and Alfvén cascades (AC) eject resonant fast ions in a convective process, an overlapping of AC and TAE spatial structures leads to a large fast-ion diffusion and loss. Diffusive fast-ion losses have been observed with a single TAE above a certain threshold in the fluctuation amplitude. PMID:20482185

  3. Tapping upgrade potential

    SciTech Connect

    Gill, H.S. )

    1993-01-01

    Modernizing aging hydropower stations presents plant owners with a unique opportunity for improving efficiency and plant output. But several factors should be considered before undertaking a turbine upgrade project.

  4. The D0 upgrade

    SciTech Connect

    Gruenendahl, S.; The D0 Collaboration

    1994-01-01

    In order to maximize the physics potential of the Fermilab Tevatron proton antiproton collider complex, both the accelerator system and the two large collider detectors are undergoing major upgrades during the remainder of this decade. For the D0 detector, the upgrade focuses on implementation of an integrated magnetic tracker in the central region of the detector, accompanied by those modifications to other parts of the apparatus necessary to cope with the increase in interaction rate provided by the collider.

  5. Optics upgrade for switchyard

    SciTech Connect

    Kobilarcik, Thomas R.; /Fermilab

    2005-08-01

    An upgrade of the Switchyard optics is proposed. This upgrade extends the P3 (old Main Ring) lattice through enclosure C. The septa for the 3-way Meson Area split is moved from enclosure F1 to enclosure M01. The functionality of the Meson Target Train is preserved. Finally, for the purpose of demonstrating that the resulting split can be transported, a straw-man lattice is proposed for enclosure M02 and beyond.

  6. Cyclotron Institute Upgrade Project

    SciTech Connect

    Clark, Henry; Yennello, Sherry; Tribble, Robert

    2014-08-26

    The Cyclotron Institute at Texas A&M University has upgraded its accelerator facilities to extend research capabilities with both stable and radioactive beams. The upgrade is divided into three major tasks: (1) re-commission the K-150 (88”) cyclotron, couple it to existing beam lines to provide intense stable beams into the K-500 experimental areas and use it as a driver to produce radioactive beams; (2) develop light ion and heavy ion guides for stopping radioactive ions created with the K-150 beams; and (3) transport 1+ ions from the ion guides into a charge-breeding electron-cyclotron-resonance ion source (CB-ECR) to produce highly-charged radioactive ions for acceleration in the K-500 cyclotron. When completed, the upgraded facility will provide high-quality re-accelerated secondary beams in a unique energy range in the world.

  7. VISIR upgrade overview and status

    NASA Astrophysics Data System (ADS)

    Kerber, Florian; Käufl, Hans Ulrich; Baksai, Pedro; Dobrzycka, Danuta; Finger, Gert; Ives, Derek; Jakob, Gerd; Lagadec, Eric; Lundin, Lars; Mawet, Dimitri; Mehrgan, Leander; Moerchen, Margaret; Momany, Yazan; Moreau, Vincent; Pantin, Eric; Riquelme, Miguel; Siebenmorgen, Ralf; Silber, Armin; Smette, Alain; Taylor, Julian; van den Ancker, Mario; Venema, Lars; Weilenmann, Ueli; Yegorova, Irina

    2012-09-01

    We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO's VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As Aquarius detector array (Raytheon) which has demonstrated very good performance (sensitivity, stability) in the laboratory IR detector test facility (modified TIMMI 2 instrument). A prism spectroscopic mode will cover the N-band in a single observation. New scientific capabilities for high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and phase-mask coronagraphic (4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a userdefined constraint on water vapour. Improved pipelines based on the ESO Reflex concept will provide better support to astronomers. The upgraded VISIR will be a powerful instrument providing background limited performance for diffraction-limited observations at an 8-m telescope. It will offer synergy with facilities such as ALMA, JWST, VLTI and SOFIA, while a wealth of targets is available from survey work (e.g. VISTA, WISE). In addition it will bring confirmation of the technical readiness and scientific value of several aspects of potential mid-IR instrumentation at Extremely Large Telescopes. The intervention on VISIR and installation of hardware has been completed in July and commissioning will take place during July and August. VISIR is scheduled to be available to the users starting Oct 2012.

  8. Antenna feedhorn software upgrade

    NASA Technical Reports Server (NTRS)

    Potter, P. D.

    1979-01-01

    The HYBRIDHORN computer program was developed to serve as an item of general purpose antenna feedhorn design and analysis software. The formulation contains a small flare angle approximation which is subject to question for designs such as the S- and X-band feedhorn. Additionally, the original formulation did not allow azimuthal variation indexes other than unity. The HYBRIDHORN program was upgraded to correct both of these deficiencies. A large flare angle formulation was found. In the upgrade, all of the major program elements were converted to Univac 1108 compatible structured FORTRAN (SFTRAN) for ease of software maintenance. The small and large angle formulations are described and sample numerical results are presented.

  9. Upgrade of the BATMAN test facility for H- source development

    NASA Astrophysics Data System (ADS)

    Heinemann, B.; Fröschle, M.; Falter, H.-D.; Fantz, U.; Franzen, P.; Kraus, W.; Nocentini, R.; Riedl, R.; Ruf, B.

    2015-04-01

    The development of a radio frequency (RF) driven source for negative hydrogen ions for the neutral beam heating devices of fusion experiments has been successfully carried out at IPP since 1996 on the test facility BATMAN. The required ITER parameters have been achieved with the prototype source consisting of a cylindrical driver on the back side of a racetrack like expansion chamber. The extraction system, called "Large Area Grid" (LAG) was derived from a positive ion accelerator from ASDEX Upgrade (AUG) using its aperture size (ø 8 mm) and pattern but replacing the first two electrodes and masking down the extraction area to 70 cm2. BATMAN is a well diagnosed and highly flexible test facility which will be kept operational in parallel to the half size ITER source test facility ELISE for further developments to improve the RF efficiency and the beam properties. It is therefore planned to upgrade BATMAN with a new ITER-like grid system (ILG) representing almost one ITER beamlet group, namely 5 × 14 apertures (ø 14 mm). Additionally to the standard three grid extraction system a repeller electrode upstream of the grounded grid can optionally be installed which is positively charged against it by 2 kV. This is designated to affect the onset of the space charge compensation downstream of the grounded grid and to reduce the backstreaming of positive ions from the drift space backwards into the ion source. For magnetic filter field studies a plasma grid current up to 3 kA will be available as well as permanent magnets embedded into a diagnostic flange or in an external magnet frame. Furthermore different source vessels and source configurations are under discussion for BATMAN, e.g. using the AUG type racetrack RF source as driver instead of the circular one or modifying the expansion chamber for a more flexible position of the external magnet frame.

  10. Analysis Efforts Supporting NSTX Upgrades

    SciTech Connect

    H.Zhang, P. Titus, P. Rogoff, A.Zolfaghari, D. Mangra, M. Smith

    2010-11-29

    The National Spherical Torus Experiment (NSTX) is a low aspect ratio, spherical torus (ST) configuration device which is located at Princeton Plasma Physics Laboratory (PPPL) This device is presently being updated to enhance its physics by doubling the TF field to 1 Tesla and increasing the plasma current to 2 Mega-amperes. The upgrades include a replacement of the centerstack and addition of a second neutral beam. The upgrade analyses have two missions. The first is to support design of new components, principally the centerstack, the second is to qualify existing NSTX components for higher loads, which will increase by a factor of four. Cost efficiency was a design goal for new equipment qualification, and reanalysis of the existing components. Showing that older components can sustain the increased loads has been a challenging effort in which designs had to be developed that would limit loading on weaker components, and would minimize the extent of modifications needed. Two areas representing this effort have been chosen to describe in more details: analysis of the current distribution in the new TF inner legs, and, second, analysis of the out-of-plane support of the existing TF outer legs.

  11. VISIR upgrade overview and status

    NASA Astrophysics Data System (ADS)

    Kerber, Florian; Käufl, Hans-Ulrich; Baksai, Pedro; Di Lieto, Nicola; Dobrzycka, Danuta; Duhoux, Philippe; Finger, Gert; Heikamp, Stephanie; Ives, Derek; Jakob, Gerd; Lundin, Lars; Mawet, Dimitri; Mehrgan, Leander; Momany, Yazan; Moreau, Vincent; Pantin, Eric; Riquelme, Miguel; Sandrock, Stefan; Siebenmorgen, Ralf; Smette, Alain; Taylor, Julian; van den Ancker, Mario; Valdes, Guillermo; Venema, Lars; Weilenmann, Ueli

    2014-07-01

    We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO's VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector array (Raytheon) which has been carefully characterized in ESO's IR detector test facility (modified TIMMI 2 instrument). A prism spectroscopic mode will cover the N-band in a single observation. New scientific capabilities for high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and phase-mask coronagraphic (4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water vapour. During the commissioning in 2012 it was found that the on-sky sensitivity of the AQUARIUS detector was significantly below expectations and that VISIR was not ready to go back to science operations. Extensive testing of the detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as excess low frequency noise (ELFN). It is inherent to the design chosen for this detector and can't be remedied by changing the detector set-up. Since this is a form of correlated noise its impact can be limited by modulating the scene recorded by the detector. We have studied several mitigation options and found that faster chopping using the secondary mirror (M2) of the VLT offers the most promising way forward. Faster M2 chopping has been tested and is scheduled for implementation before the end of 2014

  12. Biochemical upgrading of oils

    DOEpatents

    Premuzic, Eugene T.; Lin, Mow S.

    1999-01-12

    A process for biochemical conversion of heavy crude oils is provided. The process includes contacting heavy crude oils with adapted biocatalysts. The resulting upgraded oil shows, a relative increase in saturated hydrocarbons, emulsions and oxygenates and a decrease in compounds containing in organic sulfur, organic nitrogen and trace metals. Adapted microorganisms which have been modified under challenged growth processes are also disclosed.

  13. Upgrading Undergraduate Biology Education

    ERIC Educational Resources Information Center

    Musante, Susan

    2011-01-01

    On many campuses throughout the country, undergraduate biology education is in serious need of an upgrade. During the past few decades, the body of biological knowledge has grown exponentially, and as a research endeavor, the practice of biology has evolved. Education research has also made great strides, revealing many new insights into how…

  14. Biochemical upgrading of oils

    DOEpatents

    Premuzic, E.T.; Lin, M.S.

    1999-01-12

    A process for biochemical conversion of heavy crude oils is provided. The process includes contacting heavy crude oils with adapted biocatalysts. The resulting upgraded oil shows, a relative increase in saturated hydrocarbons, emulsions and oxygenates and a decrease in compounds containing organic sulfur, organic nitrogen and trace metals. Adapted microorganisms which have been modified under challenged growth processes are also disclosed. 121 figs.

  15. Temporal behavior of the plasma current distribution in the ASDEX tokamak during lower-hybrid current drive

    SciTech Connect

    McCormick, K.; Soeldner, F.X.; Eckhartt, D.; Leuterer, F.; Murmann, H.; Derfler, H.; Eberhagen, A.; Gehre, O.; Gernhardt, J.; Gierke, G.v.; and others

    1987-02-02

    Measurements of the time evolution of the current-density distribution in ASDEX show that lower-hybrid current drive leads to broader profiles, whereby q increases from qapprox. <1 to q>1 in the plasma central region. Simultaneously, the electron temperature is observed to peak, thus demonstrating that the lower-hybrid--driven current distribution is decoupled from the classical conductivity profile.

  16. Electrostatic precipitator upgrading -- Twelve years of progress

    SciTech Connect

    Grieco, G.J.

    1997-09-01

    In 1984 the author presented a paper entitled ``Electrostatic Precipitator Upgrading: A Technology Overview`` which reviewed various technologies for electrostatic precipitator performance enhancement in the utility industry. This evaluation was based on a set of criteria which included: commercial status; space requirements; required outage time for installation; installed cost; operating cost; range of applicability; and performance enhancement factor. The upgrade technologies discussed and evaluated included: gas/particulate flow upgrade; microprocessor controller retrofit; transformer-rectifier (T/R) set upgrade; pulse energization; electrode rapping modification; flue gas conditioning agents such as sulfur trioxide, ammonia and sodium; pulse energization; precipitator rebuild; and precipitator retrofit. The findings of this 1984 survey are summarized on Table 1. The installed costs listed on this table range from a low end cost associated with large precipitators with 250,000 ft{sup 2} of collecting electrode plate area and above, to a high end cost for small precipitators with only 25,000 ft{sup 2} of plate area. Twelve years later this subject is revisited and, surprisingly, significant progress has been made--this in spite of what some experts would characterize as a mature and somewhat stagnant technology field. Commercially proven techniques such as advanced flue gas conditioning, sonic horns, selective fuel blending using powder river basin coals, prudent selection of electrode geometry, and pulse energization are discussed and evaluated. Updated costs are presented for these technologies.

  17. BNL upgrade plans

    SciTech Connect

    Foelsche, H.W.J.

    1987-01-01

    Brookhaven National Laboratory is proposing two major upgrade projects for a future experimental program with protons and heavy ions. The first is the construction of a Relativistic Heavy Ion Collider (RHIC) which will use the AGS complex as an injector. The second initiative is an upgrade of the AGS proton intensity and duty cycle. Both objectives require a Booster for the AGS which has recently been approved as a construction project. With the completion of the booster, and with certain modifications of the AGS, the facility will ultimately become capable of supporting average proton currents on the order of 25 to 50 microamperes. The RHIC will provide center-of-mass collision energies of 2 x 100 to 125 GeV/amu for ions up to the heaviest masses, and 2 x 250 GeV for protons.

  18. CRYOGENICS IN BEPCII UPGRADE.

    SciTech Connect

    JIA,L.; WANG,L.; LI,S.

    2002-07-22

    THIS PAPER PRESENTS A CRYOGENIC DESIGN FOR UPGRADING THE BEIJING ELECTRON POSITRON COLLIDER AT THE INSTITUTE OF HIGH ENERGY PHYSICS IN BEIJING. THE UPGRADE INVOLVES 3 NEW SUPERCONDUCTING FACILITIES, THE INTERACTION REGION QUADRUPOLE MAGNETS, THE DETECTOR SOLENOID MAGNETS AND THE SRF CAVITIES. FOR COOLING OF THESE DEVICES, A NEW CRYPLANT WITH A TOTAL CAPACITY OF 1.0KW AT 4.5K IS TO BE BUILT AT IHEP. AN INTEGRATED CRYOGENIC DESIGN TO FIT THE BEPCII CRYOGENIC LOADS WITH HIGH EFFICIENCY IS CARRIEDOUT USING COMPUTATIONAL PROCESS ANALYSIS SOFTWARE WITH THE EMPHASES ON ECONOMICS AND SAFETY IN BOTH CONSTRUCTION AND OPERATION OF THE PLANT. THIS PAPER DESCRIBES THE CRYOGENIC CHARACTERISTICS OF EACH SUPERCONDUCTING DEVICE, THEIR COOLING SCHEMES AND THE OVERALL CRYOPLANT.

  19. Design analysis of the upgraded TREAT reactor

    SciTech Connect

    Bhattacharyya, S.K.

    1982-01-01

    The TREAT reactor, fueled by a dilute dispersion of fully enriched UO/sub 2/ in graphite, has been a premier transient testing facility since 1959. A major Upgrade of the reactor is in progress to enhance its transient testing capability in support of the LMFBR safety program. The TREAT Upgrade (TU) reactor features a modified central zone of the core with higher fissile loadings of the same fuel, clad in Inconel to allow operation at higher temperatures. The demanding functional requirements on the reactor necessitated the use of unique features in the core design which, in turn, presented major calculational complexities in the analysis. Special design methods had to be used in many cases to treat these complexities. The addition of an improved Reactor Control System, a safety grade Plant Protection System and an enhanced Coolant/Filtration System produces a reactor that can meet the functional requirements on the reactor in a safe manner.

  20. The D0 upgrade

    SciTech Connect

    Tuts, P.M. . Physics Dept.)

    1992-10-01

    The original D0 detector was proposed in 1983, with a focus on high P[sub T] physics using precision measurements of e's, [mu]'s, jets, and missing E[sub T]. This detector, as of the summer of 1992, has started data taking at the Fermilab Collider. However, by 1995/6 the luminosity will reach 10[sup 31] cm[sup [minus]2]sec[sup [minus]1], and the minimum bunch spacing will drop to 396ns from the present 3.5[mu]s (by the Main Injector era, luminosities will approach 10[sup 32] cm[sup [minus]2]sec[sup [minus]1] and minimum bunch spacings may reach 132ns). These changes in the accelerator conditions force us to upgrade or replace a number of detector subsystems in order to meet these new demands. In addition, the upgrade offers us the opportunity to expand the physics horizons to include not only the all important high P[sub T] physics menu, but also the low P[sub T] physics that has become increasingly important. In this paper we describe the D0 detector upgrade.

  1. The D0 upgrade

    SciTech Connect

    Tuts, P.M.; The D0 Collaboration

    1992-10-01

    The original D0 detector was proposed in 1983, with a focus on high P{sub T} physics using precision measurements of e`s, {mu}`s, jets, and missing E{sub T}. This detector, as of the summer of 1992, has started data taking at the Fermilab Collider. However, by 1995/6 the luminosity will reach 10{sup 31} cm{sup {minus}2}sec{sup {minus}1}, and the minimum bunch spacing will drop to 396ns from the present 3.5{mu}s (by the Main Injector era, luminosities will approach 10{sup 32} cm{sup {minus}2}sec{sup {minus}1} and minimum bunch spacings may reach 132ns). These changes in the accelerator conditions force us to upgrade or replace a number of detector subsystems in order to meet these new demands. In addition, the upgrade offers us the opportunity to expand the physics horizons to include not only the all important high P{sub T} physics menu, but also the low P{sub T} physics that has become increasingly important. In this paper we describe the D0 detector upgrade.

  2. The LHCb VELO upgrade

    NASA Astrophysics Data System (ADS)

    Rodríguez Pérez, Pablo

    2013-12-01

    LHCb is a forward spectrometer experiment dedicated to the study of new physics in the decays of beauty and charm hadrons produced in proton collisions at the Large Hadron Collider (LHC) at CERN. The VErtex LOcator (VELO) is the microstrip silicon detector surrounding the interaction point, providing tracking and vertexing measurements. The upgrade of the LHCb experiment, planned for 2018, will increase the luminosity up to 2×1033 cm-2 s-1 and will perform the readout as a trigger-less system with an event rate of 40 MHz. Extremely non-uniform radiation doses will reach up to 5×1015 1 MeV neq/cm2 in the innermost regions of the VELO sensors, and the output data bandwidth will be increased by a factor of 40. An upgraded detector is under development based in a pixel sensor of the Timepix/Medipix family, with 55 × 55 μm2 pixels. In addition a microstrip solution with finer pitch, higher granularity and thinner than the current detector is being developed in parallel. The current status of the VELO upgrade program will be described together with recent testbeam results.

  3. The LHCb VELO upgrade

    NASA Astrophysics Data System (ADS)

    Dosil Suárez, Álvaro

    2016-07-01

    The upgrade of the LHCb experiment, planned for 2019, will transform the experiment to a trigger-less system reading out the full detector at 40 MHz event rate. All data reduction algorithms will be executed in a high-level software farm. The upgraded detector will run at luminosities of 2×1033 cm-2 s-1 and probe physics beyond the Standard Model in the heavy flavour sector with unprecedented precision. The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40 MHz. The detector comprises silicon pixel sensors with 55×55 μm2 pitch, read out by the VeloPix ASIC, based on the TimePix/MediPix family. The hottest region will have pixel hit rates of 900 Mhits/s yielding a total data rate more than 3 Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separated from the beam vacuum by a thin custom made foil. The detector halves are retracted when the beams are injected and closed at stable beams, positioning the first sensitive pixel at 5.1 mm from the beams. The material budget will be minimised by the use of evaporative CO2 coolant circulating in microchannels within 400 μm thick silicon substrates.

  4. AMI FW UPGRADEABILITY TEST PROCEDURE AND SECURITY ASSESSMENT

    SciTech Connect

    Snyder, Isabelle B

    2014-01-01

    The National Institute of Standards and Technology (NIST) is producing NISTIR 7823 to define test requirements for Smart Meter upgradability. The term Smart Meter refers specifically to advanced electric meters being deployed to enhance management of electricity distribution for residential and industrial consumers. The underlying functional and security requirements for Smart Meter upgradability are specified in NEMA standard SG-AMI 1-2009. The purpose of NISTIR 7823 is to describe conformance test requirements that may be used voluntarily by testers and/or test laboratories to determine whether Smart Meters and Upgrade Management Systems conform to the requirements of NEMA SG-AMI 1-2009.

  5. The LHCb Upgrade

    NASA Astrophysics Data System (ADS)

    Jacobsson, Richard

    2013-11-01

    With the demonstration that LHCb can successfully perform forward precision measurements with event pileup, the operation and trigger strategy evolved significantly during the LHC Run 1 allowing LHCb to collect over 3fb-1 at centre-of-mass energies of 7TeV and 8TeV. Increased bandwidth opened the door for LHCb to extend the physics program. The additional statistics and well managed systematic effects together with the stable trigger and data taking conditions have led to a very large number of world-class measurements and dominance in heavy flavour physics [1], in addition to a reputation of an excellent forward general purpose detector at the LHC. Long Shutdown (LS) 1 (2013-2014) will allow LHCb to fully explore the large statistics collected and prepare LHCb for Run 2 (2015 - 2017). However, even after an additional expected integrated luminosity of 5-6 fb-1 in Run 2, many of the LHCb precision measurements will remain limited by statistics, and some exploratory physics modes will not even be accessible yet. With the need for reconstructing the event topology in order to efficiently trigger on the beauty and the charm hadrons decays, the current 1 MHz readout limit is the main bottle neck to run at higher luminosity and with higher trigger efficiencies. LHCb will therefore undergo a major upgrade in LS 2 ( 2018 - 2019) aimed at collecting an order of magnitude more data by 2028. The upgrade consists of a full readout at the LHC bunch crossing rate ( 40 MHz) with the ultimate flexibility of only a software trigger. In order to increase the instantaneous luminosity up to 2x1033cm-2s-1, several sub-detector upgrades are also underway to cope with the higher occupancies and radiation dose.

  6. The Bevalac Upgrade Project

    SciTech Connect

    Alonso, J.R.; Dwinell, R.D.; Feinberg, B.; Frias, R.; Gough, R.A.; Howard, D.R.; Hunt, D.B.; Krebs, G.F.; Krupnick, J.T.; Lewis, S.A.

    1987-03-01

    This paper describes a proposed upgrade of the Bevalac accelerator complex in which the present Bevatron is replaced with a modern, strong-focusing 17 T-m synchrotron. This new ring is designed to accelerate all ions throughout the periodic table with intensities 100 to 1000 times higher than the present Bevatron. It will also provide a substantially improved beam spill structure and will reduce operating costs. A fast extraction capability can be used to inject a future heavy ion storage ring. Pulse-to-pulse switching of energy and ion species is an important goal. The existing injectors, shielding, experimental facilities and utilities of the present Bevalac will remain substantially intact.

  7. 'Upgrading' psoriasis responsibly.

    PubMed

    Boehncke, Sandra; Boehncke, Wolf-Henning

    2014-10-01

    Psoriasis is a 'pacemaker' in dermatology. Substantial progress has been made regarding our understanding of its pathophysiology and genetic background, fuelling developments in cutaneous biology in general. Besides, the clinical perspective on psoriasis is currently changing, taking into consideration comorbidity and the systemic dimensions of this seemingly organ-specific inflammation. The availability of drugs exhibiting fewer contraindications and improved long-term safety opened a discussion around replacing a relatively limited (regarding both objectives and duration) 'therapeutic' by a much broader 'management' approach when it comes to treating psoriasis as a systemic disease. The question arises whether this 'upgrade' is warranted. PMID:25040560

  8. Upgraded Coal Interest Group

    SciTech Connect

    Evan Hughes

    2009-01-08

    The Upgraded Coal Interest Group (UCIG) is an EPRI 'users group' that focuses on clean, low-cost options for coal-based power generation. The UCIG covers topics that involve (1) pre-combustion processes, (2) co-firing systems and fuels, and (3) reburn using coal-derived or biomass-derived fuels. The UCIG mission is to preserve and expand the economic use of coal for energy. By reducing the fuel costs and environmental impacts of coal-fired power generation, existing units become more cost effective and thus new units utilizing advanced combustion technologies are more likely to be coal-fired.

  9. Research ships upgraded

    NASA Astrophysics Data System (ADS)

    Two research vessels, operated by the Scripps Institution of Oceanography, University of California, San Diego, and Woods Hole Oceanographic Institution, Woods Hole, Mass., are undergoing scientific upgrading and engineering modifications costing $15 million each. The improvements will prepare them to take lead roles in major future ocean research efforts.Research vessel Knorr (operated by WHOI) entered the McDermott Shipyard in Amelia, LA., on February 15. It will receive new engines and a propulsion system, and its length will be increased from 245 to 279 feet. The R/V Melville (operated by SIO) is scheduled for the same 10-month remodeling to begin in mid-November.

  10. LHC detector upgrades

    SciTech Connect

    Dan Green

    2003-09-15

    The LHC detectors are well into their construction phase. The LHC schedule shows first beam to ATLAS and CMS in 2007. Because the LHC accelerator has begun to plan for a ten fold increase in LHC design luminosity (the SLHC or super LHC) it is none too soon to begin to think about the upgrades which will be required of the present LHC detectors. In particular, the tracking systems of ATLAS and CMS will need to be completely rebuilt. Given the time needed to do the R & D, make prototypes, and construct the new detectors and given the accelerator schedule for the SLHC, work needs to begin rather soon.

  11. Parametric investigation of the density profile in the scrape-off layer of ASDEX

    NASA Astrophysics Data System (ADS)

    McCormick, K.; Pietrzyk, Z. A.; Murmann, H.; Lenoci, M.; ASDEX Team; Becker, G.; Bosch, H. S.; Brocken, H.; Bühl, K.; Eberhagen, A.; Eckhartt, D.; Fussmann, G.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Glock, E.; Gruber, O.; Haas, G.; Hofmann, J.; Izvozchikov, A.; Janeschitz, G.; Karger, F.; Kaufmann, M.; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lang, R. S.; Leuterer, F.; Lisitano, G.; Mast, F.; Mayer, H. M.; Meisel, D.; Mertens, V.; Müller, E. R.; Neuhauser, J.; Noterdaeme, J.-M.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Riedler, H.; Röhr, H.; Roth, J.; Ryter, F.; Sandmann, W.; Schneider, F.; Setzensack, C.; Siller, G.; Smeulders, P.; Söldner, F. X.; Speth, E.; Steinmetz, K.; Steuer, K.-H.; Tsois, N.; Ugniewski, S.; Vlases, G.; Vollmer, O.; Wagner, F.; Wesner, F.; Zasche, D.

    1987-02-01

    Systematic investigations of the scrape-off layer (SOL) in the midplane of ASDEX have been carried out in He, D 2 and H 2 for diverted ohmic discharges over a wide range of plasma conditions: overlinene ˜ 0.5-4.7 × 10 13 cm -3, Ip = 200-450 kA, BT = 16-23 kG, qa˜ 2.4-4.4 and POH = 200-480 kW. For the first two cm outside the separatix, ne is found to decay exponentially with an e-folding length λn given by λn = kqα (He, k = 1.32 cm, α = 0.52; D 2, k =1.29 cm, α = 0.35; H 2, k = 1.18 cm, α = 0.4) when from which follows for qa = 3: λn( D2) ˜ λn( H2) ˜ 0.8 λn( He). The qα scaling is roughly predicted by the simple formula λ n = {D ⊥ L }/{υ ∥} under the assumption D⊥ ∝ mi-0.5 (as has been observed on ASDEX for H 2 and D 2). There appears to be no explicit λn dependence on heating power. λn varies strongly with overlinene in the range overlinene ≤ 1 × 10 13 cm -3, decreasing for example (D 2,H 2; qa = 3.0), from λn ≥ 3 cm at overlinene ˜ 0.5 × 10 13 cm -3 to λn ˜ 1.9 cm for overlinene ≥ 1.5 × 10 13 cm -3, ne at the separatrix is primarily a function of overlinene.

  12. Upgraded demonstration vehicle task report

    NASA Technical Reports Server (NTRS)

    Bryant, J.; Hardy, K.; Livingston, R.; Sandberg, J.

    1981-01-01

    Vehicle/battery performance capabilities and interface problems that occurred when upgraded developmental batteries were integrated with upgraded versions of comercially available electric vehicles were investigated. Developmental batteries used included nickel zinc batteries, a nickel iron battery, and an improved lead acid battery. Testing of the electric vehicles and upgraded batteries was performed in the complete vehicle system environment to characterize performance and identify problems unique to the vehicle/battery system. Constant speed tests and driving schedule range tests were performed on a chassis dynamometer. The results from these tests of the upgraded batteries and vehicles were compared to performance capabilities for the same vehicles equipped with standard batteries.

  13. SNO+ Readout Electronics Upgrades

    NASA Astrophysics Data System (ADS)

    Bonventre, Richard; Shokair, Timothy; Knapik, Robert

    2012-03-01

    The SNO+ experiment is designed to explore several topics in neutrino physics including neutrinoless double beta decay, reactor antineutrinos, and low energy solar neutrinos. SNO+ uses the existing Sudbury Neutrino Observatory (SNO) detector, with the heavy water target replaced with liquid scintillator. The new target requires an upgrade to the command and control electronics to handle the higher rates expected with scintillation light as compared to Cherenkov light. The readout electronics have been upgraded to autonomously push data to a central data acquisition computer over ethernet from each of the 19 front end crates. The autonomous readout is achieved with a field programmable gate array (FPGA) with an embedded processor. Inside the FPGA fabric a state machine is configured to pull data across the VME-like bus of each crate. A small C program, making use of the open source Light Weight IP (LWIP) libraries, is run directly on the hardware (with no operating system) to push the data via TCP/IP. The hybrid combination of `high-level' C code and a `low-level' VHDL state machine is a cost effective and flexible solution for reading out individual front end crates.

  14. Energy Efficiency Upgrades

    SciTech Connect

    Roby Williams

    2012-03-29

    The energy efficiency upgrades project at Hardin County General Hospital did not include research nor was it a demonstration project. The project enabled the hospital to replace outdated systems with modern efficient models. Hardin County General Hospital is a 501c3, nonprofit hospital and the sole community provider for Hardin and Pope Counties of Illinois. This project provided much needed equipment and facility upgrades that would not have been possible through locally generated funding. Task 1 was a reroofing of the hospital. The hospital architect designed the replacement to increase the energy efficiency of the hospital roof/ceiling structure. Task 2 was replacement and installation of a new more efficient CT scanner for the hospital. Included in the project was replacement of HVAC equipment for the entire radiological suite. Task 5 was a replacement and installation of a new higher capacity diesel-fueled emergency generator for the hospital replacing a 50+ year old gas-fired generator. Task 7 was the replacement of 50+ year-old walk-in cooler/freezer with a newer, energy efficient model. Task 8 was the replacement of 10+ year-old washing machines in the hospital laundry with higher capacity, energy efficient models. Task 9 was replacement of 50-year old single pane curtain window system with double-pane insulated windows. Additionally, insulation was added around ventilation systems and the curtain wall system.

  15. HP upgrade operational streamlining

    NASA Technical Reports Server (NTRS)

    Edge, David R.; Emenheiser, Kenneth S.; Hanrahan, William P., III; Mccollums, D.; Seery, Paul J.; Ricklefs, Randall L.

    1993-01-01

    New computer technology and resources must be successfully integrated into CDSLR station operations to manage new complex operational tracking requirements, support the on site production of new data products, support ongoing station performance improvements, and to support new station communication requirements. The NASA CDSLR Network is in the process of upgrading station computer resources with HP UNIX workstations, designed to automate a wide range of operational station requirements. The primary HP upgrade objective was to relocate computer intensive data system tasks from the controller computer to a new advanced computer environment designed to meet the new data system requirements. The HP UNIX environment supports fully automated real time data communications, data management, data processing, and data quality control. Automated data compression procedures are used to improve the efficiency of station data communications. In addition, the UNIX environment supports a number of semi-automated technical and administrative operational station tasks. The x window user interface generates multiple simultaneous color graphics displays, providing direct operator visibility and control over a wide range of operational station functions.

  16. Recharging of the ohmic-heating transformer by means of lower-hybrid current drive in the ASDEX tokamak

    NASA Astrophysics Data System (ADS)

    Leuterer, F.; Eckhartt, D.; Söldner, F.; Becker, G.; Bernhardi, K.; Brambilla, M.; Brinkschulte, H.; Derfler, H.; Ditte, U.; Eberhagen, A.; Fussman, G.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Glock, E.; Gruber, O.; Haas, G.; Hesse, M.; Janeschitz, G.; Karger, F.; Keilhacker, M.; Kissel, S.; Klüber, O.; Kornherr, M.; Lisitano, G.; Magne, R.; Mayer, H. M.; McCormick, K.; Meisel, D.; Mertens, V.; Müller, E. R.; Münich, M.; Murmann, H.; Poschenrieder, W.; Rapp, H.; Ryter, F.; Schmitter, K. H.; Schneider, F.; Siller, G.; Smeulders, P.; Steuer, K. H.; Vien, T.; Wagner, F.; Woyna, F. V.; Zouhar, M.

    1985-07-01

    Recharging of the Ohmic-heating transformer of a tokamak by means of lower-hybrid waves is demonstrated experimentally in ASDEX. The results are analyzed on the basis of a simple transformer circuit. A recharging efficiency is defined and found to depend on rf power, plasma density, and plasma resistivity modified by the applied rf power. Up to now, we achieved in our recharging experiments in ASDEX a flux swing of FİOHMdt=0.24 V sec, at an rf power of PRF=690 kW, with a pulse duration of 1 sec, while maintaining a plasma with n¯e=4×1012 cm-3 and Ip=290 kA.

  17. RHIC OPERATIONAL STATUS AND UPGRADE PLANS.

    SciTech Connect

    FISCHER, W.

    2006-06-23

    Since 2000 RHIC has collided, at 8 energies, 4 combinations of ion species, ranging from gold ions to polarized protons, and including the collisions of deuterons with gold ions. During that time the heavy ion and polarized proton peak luminosities increased by two orders and one order of magnitude respectively. The average proton polarization in store reached 65%. Planned upgrades include the evolution to the Enhanced Design parameters by about 2008, the construction of an Electron Beam Ion Source (EBIS) by 2009, the installation of electron cooling for RHIC II, and the implementation of the electron-ion collider eRHIC. We review the current performance, and the expected performance with these upgrades.

  18. Rate enhancement for catalytic upgrading coal naphthas

    SciTech Connect

    Davis, B.H.

    1992-01-01

    The removal of heteroatoms from naphtha using first row unsupported metal sulfide catalysts were completed. The maxima HDS activity, normalizing to the same weight of metal, is obtained for manganese sulfide while the minimum HDS activity is obtained for nickel sulfide. Chianelli et al. (1) reported that, for the first row transition metal sulfides, chromium sulfide has the highest activity for HDS of dibenzothiophene and manganese sulfide is the least active. The catalyst activity pattern of the first row transition metal sulfide for hydrodesulfurization of naphtha and dibenzothiophene is different. The maxima HDN activity, normalizing to the same weight of metal, is obtained for chromium sulfide and the minimum HDN activity is obtained for cobalt sulfide. The effect of substituents on the conversion of nitrogen compounds from the naphtha was also determined. The HDN conversion of alkyl-substituted pyridines and anilines are dominated by electronic effects rather than substituent effects. The effect of alkyl-substitution on the conversion of quinolines is relatively insignificant.

  19. Rate enhancement for catalytic upgrading coal naphthas

    SciTech Connect

    Liaw, Shuh Jeng; Keogh, R.A.; Davis, B.H.

    1992-01-01

    The amount of individual nitrogen and sulfur presented in the feed and hydrotreated Illinois [number sign]6 naphtha were determined. The major nitrogen class in the naphtha are anilines. The major sulfur components identified are thiophenes and benzothiophenes. The aniline and quinoline is harder to remove than pyridine. The aniline and pyridine, without any carbon substituted, is the easiest one to remove in their class. The quinoline, without any carbon substituted, is approximately as hard as one carbon substituted quinoline to remove. Both Co-Mo and Ni-W catalysts follow the similar pattern of the nitrogen removal at different temperatures. The sulfur compounds of the Ill. [number sign]6 naphtha was separated to three classes, i.e. sulfides and thiols, thiophenes and benzothiophenes, for comparisons. The thiophenes was the major component of the hydrotreated naphtha at most temperatures; however, the sulfides and thiols class becomes the major component at temperatures greater than 300[degree]C.

  20. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will also be investigated.

  1. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  2. TMX upgrade experimental operating plan

    SciTech Connect

    Coensgen, F.H.; Davis, J.C.; Simonen, T.C.

    1981-07-01

    This document describes the operating plan for the TMX Upgrade experiment. This plan covers the period from November 1981 to March 1983 and describes how the TMX will be brought into operation, our schedules and milestones, and how we will determine if the TMX Upgrade program milestones have been met.

  3. Skill Upgrading, Incorporated. Final Report.

    ERIC Educational Resources Information Center

    Skill Upgrading, Inc., Baltimore, MD.

    As in two other projects in Cleveland and Newark, New Jersey, this project was set up in Baltimore to provide technical assistance in designing ways to meet in-plant skills needs by upgrading job skills on entry workers through High Intensity Training (HIT). Skill Upgrading, Inc. was established in Maryland to provide training and manpower…

  4. NIRSS Upgrades: Final Report

    NASA Technical Reports Server (NTRS)

    Politovich, Marcia K.

    2007-01-01

    This year we were able to further the NIRSS program by re-writing the data ingest and display code from LabVIEW to C++ and Java. This was leveraged by a University of Colorado Computer Science Department Senior Project. The upgrade made the display more portable and upgradeable. Comparisons with research aircraft flights conducted during AIRS-2 were also done and demonstrate reasonable skill in determining cloud altitudes and liquid water distribution. Improvements can still be made to the cloud and liquid logic. The icing hazard index was not evaluated here since that represents work in progress and needs to be made compatible with the new CIP-Severity algorithm. CIP is the Current Icing Potential product that uses a combination decision tree/fuzzy logic algorithm to combine numerical weather model output with operational sensor data (NEXRAD, GOES, METARs and voice pilot reports) to produce an hourly icing diagnosis across the CONUS. The new severity algorithm seeks to diagnose liquid water production through rising, cooling air, and depletion by ice processes. The information used by CIP is very different from that ingested by NIRSS but some common ground does exist. Additionally, the role of NIRSS and the information it both needs and provides needs to be determined in context of the Next Generation Air Traffic System (NGATS). The Weather Integrated Products Team has a plan for an Initial Operating Capability (IOC) to take place in 2012. NIRSS is not explicitly a part of that IOC but should be considered as a follow-on as part of the development path to a 2025 full capability.

  5. ETA-II accelerator upgrades

    SciTech Connect

    Nilson, D.G.; Deadrick, F.J.; Hibbs, S.M.; Sampayan, S.E.; Petersen, D.E.

    1991-09-01

    We discuss recent improvements to the ETA-II linear induction electron accelerator. The accelerator's cells have been carefully reconditioned to raise the maximum accelerating gap voltage from approximately 100 kV to 125 kV. Insulators of Rexolite plastic in a new zero-gap'' arrangement replaced the alumina originals after several alternative materials were investigated. A new multi-cable current feed system will be used to eliminate pulse reflection interactions encountered in earlier experiments. Improved alignment fixtures have been installed to help minimize beam perturbation due to poorly aligned intercell magnets between 10-cell groups. A stretched wire alignment technique (SWAT) has been utilized to enhance overall magnetic alignment, and to characterize irreducible alignment errors. These changes are in conjunction with an expansion of the accelerator from a 20-cell to a 60-cell configuration. When completed, the upgraded accelerator is expected to deliver 2.5 kA of electron beam current at 7.5 MeV in bursts of up to fifty 70-ns pulses at a 5-kHz repetition rate. A 5.5-meter-long wiggler will convert the energy into 3-GW microwave pulses at 140 GHz for plasma heating experiments in the Microwave Tokamak Experiment (MTX).

  6. ETA-II accelerator upgrades

    SciTech Connect

    Nilson, D.G.; Deadrick, F.J.; Hibbs, S.M.; Sampayan, S.E.; Petersen, D.E.

    1991-09-01

    We discuss recent improvements to the ETA-II linear induction electron accelerator. The accelerator`s cells have been carefully reconditioned to raise the maximum accelerating gap voltage from approximately 100 kV to 125 kV. Insulators of Rexolite plastic in a new ``zero-gap`` arrangement replaced the alumina originals after several alternative materials were investigated. A new multi-cable current feed system will be used to eliminate pulse reflection interactions encountered in earlier experiments. Improved alignment fixtures have been installed to help minimize beam perturbation due to poorly aligned intercell magnets between 10-cell groups. A stretched wire alignment technique (SWAT) has been utilized to enhance overall magnetic alignment, and to characterize irreducible alignment errors. These changes are in conjunction with an expansion of the accelerator from a 20-cell to a 60-cell configuration. When completed, the upgraded accelerator is expected to deliver 2.5 kA of electron beam current at 7.5 MeV in bursts of up to fifty 70-ns pulses at a 5-kHz repetition rate. A 5.5-meter-long wiggler will convert the energy into 3-GW microwave pulses at 140 GHz for plasma heating experiments in the Microwave Tokamak Experiment (MTX).

  7. Upgrades to Monteburns, version 3.0

    SciTech Connect

    Galloway, J. D.; Trellue, H. R.

    2012-07-01

    Monteburns, a Monte Carlo burnup code which has the flexibility to model time-dependent isotopic changes for a variety of nuclear systems by linking the neutron transport code MCNP/X to a production/depletion code, has undergone several performance upgrades recently that have increased the code's capabilities. Once limited to a specific number of regions, enhancements have been implemented that afford a much greater number of burn materials, such that users will be more limited by the physical constraints of their computing environment as opposed to inherent limits built into the coding of Monteburns. In conjunction with the increase in the number of burn materials, parallel execution of a production/depletion code of choice has been implemented, such that users have the option of using CINDER90, 0RIGEN2, or the newly released version of ORIGEN. Finally, the recoverable energy per fission calculation was upgraded to include capture gamma energy deposited in all specified materials as a function of irradiation time. The sum of the prompt and delayed recoverable energies from fission was obtained as before. These upgrades were first tested on a rigorous 1/8 core model of a Pressurized Water Reactor with fresh, once- and twice-burned fuel. We can now model several orders of magnitude more materials using Monte Carlo techniques, which is a significant advance in the reactor modeling world. (authors)

  8. NSTX-U Control System Upgrades

    SciTech Connect

    Erickson, K. G.; Gates, D. A.; Gerhardt, S. P.; Lawson, J. E.; Mozulay, R.; Sichta, P.; Tchilinguirian, G. J.

    2014-06-01

    The National Spherical Tokamak Experiment (NSTX) is undergoing a wealth of upgrades (NSTX-U). These upgrades, especially including an elongated pulse length, require broad changes to the control system that has served NSTX well. A new fiber serial Front Panel Data Port input and output (I/O) stream will supersede the aging copper parallel version. Driver support for the new I/O and cyber security concerns require updating the operating system from Redhat Enterprise Linux (RHEL) v4 to RedHawk (based on RHEL) v6. While the basic control system continues to use the General Atomics Plasma Control System (GA PCS), the effort to forward port the entire software package to run under 64-bit Linux instead of 32-bit Linux included PCS modifications subsequently shared with GA and other PCS users. Software updates focused on three key areas: (1) code modernization through coding standards (C99/C11), (2) code portability and maintainability through use of the GA PCS code generator, and (3) support of 64-bit platforms. Central to the control system upgrade is the use of a complete real time (RT) Linux platform provided by Concurrent Computer Corporation, consisting of a computer (iHawk), an operating system and drivers (RedHawk), and RT tools (NightStar). Strong vendor support coupled with an extensive RT toolset influenced this decision. The new real-time Linux platform, I/O, and software engineering will foster enhanced capability and performance for NSTX-U plasma control.

  9. NSLS control system upgrade status

    SciTech Connect

    Smith, J.; Ramamoorthy, S.; Tang, Y.; Flannigan, J.; Sathe, S.; Keane, J.; Krinsky, S.

    1993-07-01

    The NSLS control system initially installed in 1978 has undergone several modifications but the basic system architecture remained relatively unchanged. The need for faster response, increased reliability and better diagnostics made the control system upgrade a priority. Since the NSLS runs continuously, major changes to the control system are difficult. The upgrade plan had to allow continuous incremental changes to the control system without having any detrimental effect on operations. The plan had to provide for immediate improvement in a few key areas, such as data access rates, and be complete in a short time. At present, most accelerator operations utilize the upgraded control system.

  10. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    In this project we intend to study a novel process concept, i.e, the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  11. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    In this project we intend to study a novel process concept, i.e.,the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we wig evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  12. Upgrading Diagnostic Diagrams

    NASA Astrophysics Data System (ADS)

    Proxauf, B.; Kimeswenger, S.; Öttl, S.

    2014-04-01

    Diagnostic diagrams of forbidden lines have been a useful tool for observers in astrophysics for many decades now. They are used to obtain information on the basic physical properties of thin gaseous nebulae. Moreover they are also the initial tool to derive thermodynamic properties of the plasma from observations to get ionization correction factors and thus to obtain proper abundances of the nebulae. Some diagnostic diagrams are in wavelengths domains which were difficult to take either due to missing wavelength coverage or low resolution of older spectrographs. Thus they were hardly used in the past. An upgrade of this useful tool is necessary because most of the diagrams were calculated using only the species involved as a single atom gas, although several are affected by well-known fluorescence mechanisms as well. Additionally the atomic data have improved up to the present time. The new diagnostic diagrams are calculated by using large grids of parameter space in the photoionization code CLOUDY. For a given basic parameter the input radiation field is varied to find the solutions with cooling-heating-equilibrium. Empirical numerical functions are fitted to provide formulas usable in e.g. data reduction pipelines. The resulting diagrams differ significantly from those used up to now and will improve the thermodynamic calculations.

  13. Naphtha upgrading process

    SciTech Connect

    Mc Guiness, M.P.; Mitchell, K.M.; Ware, R.A.

    1987-03-03

    A method is described for upgrading a paraffinic naphtha including major amounts of C/sub 5/ and C/sub 6/ components to produce gasoline boiling range products of improved octane number, which comprises (i) hydrocracking the naphtha over a hydrocracking catalyst comprising zeolite beta and a hydrogenation-dehydrogenation component under conditions of elevated temperature and pressure and in the presence of hydrogen and at a conversion of not more than 25 volume percent to C/sub 5-/ products. This is done to effect a partial, preferential hydrocracking of the paraffins of relatively longer chain length in the naphtha and a concurrent isomerization of n-paraffins, to form a hydrocracking effluent comprising isobutane and higher boiling materials; (ii) fractionating the hydrocracked effluent to form (i) an isobutane stream, (ii) a relatively low boiling stream having a boiling range of approximately C/sub 5/ to 200/sup 0/F. and comprising C/sub 5/ to C/sub 7/ iso-paraffins, and (iii) a relatively higher boiling stream having an initial boiling point of approximately 200/sup 0/F., and (iii) reforming the relatively high boiling point stream to form a gasoline boiling range product of improved octane rating.

  14. The D0 upgrade trigger

    SciTech Connect

    Eno, S.

    1994-09-01

    The current trigger system for the D0 detector at Fermilab`s Tevatron will need to be upgraded when the Min Injector is installed and the Tevatron can operate at luminosities exceeding 10{sup 32} cm{sup {minus}2}s{sup {minus}1} and with a crossing time of 132 ns. We report on preliminary designs for upgrades to the trigger system for the Main Injector era.

  15. Upgrading in an Industrial Setting. Final Report.

    ERIC Educational Resources Information Center

    Russell, Wendell

    The project objectives were: (1) to assess existing industrial upgrading practices in an Atomic Energy Commission contractor organization, (2) to design new alternative upgrading methods, (3) to experiment with new upgrading methods, (4) to plan for utilization of proven upgrading programs, and (5) to document and disseminate activities. A twelve…

  16. Setting priorities for safeguards upgrades

    SciTech Connect

    Al-Ayat, R.A.; Judd, B.R.; Patenaude, C.J.; Sicherman, A.

    1987-07-10

    This paper describes an analytic approach and a computer program for setting priorities among safeguards upgrades. The approach provides safeguards decision makers with a systematic method for allocating their limited upgrade resources. The priorities are set based on the upgrades cost and their contribution to safeguards effectiveness. Safeguards effectiveness is measured by the probability of defeat for a spectrum of potential insider and outsider adversaries. The computer program, MI$ER, can be used alone or as a companion to ET and SAVI, programs designed to evaluate safeguards effectiveness against insider and outsider threats, respectively. Setting the priority requires judgments about the relative importance (threat likelihoods and consequences) of insider and outsider threats. Although these judgments are inherently subjective, MI$ER can analyze the sensitivity of the upgrade priorities to these weights and determine whether or not they are critical to the priority ranking. MI$ER produces tabular and graphical results for comparing benefits and identifying the most cost-effective upgrades for a given expenditure. This framework provides decision makers with an explicit and consistent analysis to support their upgrades decisions and to allocate the safeguards resources in a cost-effective manner.

  17. Setting priorities for safeguards upgrades

    SciTech Connect

    Al-Ayat, R.A.; Judd, B.R.; Patenaude, C.J.; Sicherman, A.

    1987-07-01

    This paper describes an analytic approach and a computer program for setting priorities among safeguards upgrades. The approach provides safeguards decision makers with a systematic method for allocating their limited upgrade resources. The priorities are set based on the upgrades cost and their contribution to safeguards effectiveness. Safeguards effectiveness is measured by the probability of defeat for a spectrum of potential insider and outsider adversaries. The computer program, MI$ER, can be used alone or as a companion to ET and SAVI, programs designed to evaluate safeguards effectiveness against insider and outsider threats, respectively. Setting the priority required judgments about the relative importance (threat likelihoods and consequences) of insider and outsider threats. Although these judgments are inherently subjective, MI$ER can analyze the sensitivity of the upgrade priorities to these weights and determine whether or not they are critical to the priority ranking. MI$ER produces tabular and graphical results for comparing benefits and identifying the most cost-effective upgrades for a given expenditure. This framework provides decision makers with an explicit and consistent analysis to support their upgrades decisions and to allocate the safeguards resources in a cost-effective manner.

  18. First results on lower hybrid current drive at 2. 45 GHz in ASDEX

    SciTech Connect

    Leuterer, F.; Soldner, F.X.; Buechse, R.; Carlson, A.; Eberhagen, A.; Fahrbach, H.; Gehre, O.; Hassenpflug, F.; Herrmann, W.; Janeschitz, G.; Kornherr, M.; Luce, T.; McKormick, K.; Monaco, F.; Muenich, M.; Murmann, H.; Pelicano, M.; Steuer, K.; Zouhar, M. ); Bartiromo, R.; DeAngelis, R.; Pericoli, V.; Santini, F.; Tuccillo, A. ); Bernabei, S.; Forrest, C. ); ASDEX-team

    1989-07-01

    A new lower hybrid system with 2.45 GHz/3 MW/1 sec has started operation on ASDEX. Current drive effects have been identified up to a density of {bar n}{sub e}=4.7 {center dot} 10{sup 13} cm{sup {minus}3}. Full current drive at I{sub p}=420 kV was achieved up to a density of {bar n}{sub e}=2.1 {center dot} 10{sup 13} cm{sup {minus}3}. The effeciency was maximum at {bar n}{sub e}=1.35 {center dot} 10{sup 13} cm{sup {minus}3} and reached {eta}=1.46 (10{sup 13} cm{sup {minus}3} {center dot} A {center dot} m/W). The electron temperature is peaking and reached peak values up to 6 keV, while the electron density profile flattens. Sawteeth have been stabilized up to a density of {bar n}{sub e}=3.4 {center dot} 10{sup 13} cm{sup {minus}3}. The global confinement times decreases with increasing rf-power. The scaling can be described by an offset linear relation. At low density global confinement is better during the LH-phase than in the OH-phase at the same total power input.

  19. Five-Segment Reusable Solid Rocket Booster Upgrade

    NASA Technical Reports Server (NTRS)

    Sauvageau, Don

    1999-01-01

    The Five Segment Reusable Solid Rocket Booster (RSRB) feasibility status is presented in viewgraph form. The Five Segment Booster (FSB) objective is to provide a low cost, low risk approach to increase reliability and safety of the Shuttle system. Topics include: booster upgrade requirements; design summary; reliability issues; booster trajectories; launch site assessment; and enhanced abort modes.

  20. User and Performance Impacts from Franklin Upgrades

    SciTech Connect

    He, Yun

    2009-05-10

    The NERSC flagship computer Cray XT4 system"Franklin" has gone through three major upgrades: quad core upgrade, CLE 2.1 upgrade, and IO upgrade, during the past year. In this paper, we will discuss the various aspects of the user impacts such as user access, user environment, and user issues etc from these upgrades. The performance impacts on the kernel benchmarks and selected application benchmarks will also be presented.

  1. Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak

    NASA Astrophysics Data System (ADS)

    Wagner, F.; Becker, G.; Behringer, K.; Campbell, D.; Eberhagen, A.; Engelhardt, W.; Fussmann, G.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Haas, G.; Huang, M.; Karger, F.; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lisitano, G.; Lister, G. G.; Mayer, H. M.; Meisel, D.; Müller, E. R.; Murmann, H.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Röhr, H.; Schneider, F.; Siller, G.; Speth, E.; Stäbler, A.; Steuer, K. H.; Venus, G.; Vollmer, O.; Yü, Z.

    1982-11-01

    A new operational regime has been observed in neutral-injection-heated ASDEX divertor discharges. This regime is characterized by high βp values comparable to the aspect ratio A (βp<=0.65A) and by confinement times close to those of Ohmic discharges. The high-βp regime develops at an injection power >=1.9 MW, a mean density n¯e>=3×1013 cm-3, and a q(a) value >=2.6. Beyond these limits or in discharges with material limiter, low βp values and reduced particle and energy confinement times are obtained compared to the Ohmic heating phase.

  2. A Cooling System for the EAPU Shuttle Upgrade

    NASA Technical Reports Server (NTRS)

    Tongue, Stephen; Guyette, Greg; Irbeck, Bradley

    2001-01-01

    The Shuttle orbiter currently uses hydrazine-powered APU's for powering its hydraulic system pumps. To enhance vehicle safety and reliability, NASA is pursuing an APU upgrade where the hydrazine powered turbine is replaced by an electric motor pump and battery power supply. This EAPU (Electric APU) upgrade presents several thermal control challenges most notably the new requirement for moderate temperature control of high-power electron ics at 132 of (55.6 C). This paper describes how the existing Water Spray Boiler (WSB), which currently cools the hydraulic fluid and APU lubrication oil, is being modified to provide EAPU thermal management.

  3. First operations with the new Collective Thomson Scattering diagnostic on the Frascati Tokamak Upgrade device

    NASA Astrophysics Data System (ADS)

    Bin, W.; Bruschi, A.; D'Arcangelo, O.; Castaldo, C.; De Angeli, M.; Figini, L.; Galperti, C.; Garavaglia, S.; Granucci, G.; Grosso, G.; Korsholm, S. B.; Lontano, M.; Mellera, V.; Minelli, D.; Moro, A.; Nardone, A.; Nielsen, S. K.; Rasmussen, J.; Simonetto, A.; Stejner, M.; Tartari, U.

    2015-10-01

    Anomalous emissions were found over the last few years in spectra of Collective Thomson Scattering (CTS) diagnostics in tokamak devices such as TEXTOR, ASDEX and FTU, in addition to real CTS signals. The signal frequency, down-shifted with respect to the probing one, suggested a possible origin in Parametric Decay Instability (PDI) processes correlated with the presence of magnetic islands and occurring for pumping wave power levels well below the threshold predicted by conventional models. A threshold below or close to the Electron Cyclotron Resonance Heating (ECRH) power levels could limit, under certain circumstances, the use of the ECRH in fusion devices. An accurate characterization of the conditions for the occurrence of this phenomenon and of its consequences is thus of primary importance. Exploiting the front-steering configuration available with the real-time launcher, the implementation of a new CTS setup now allows studying these anomalous emission phenomena in FTU under conditions of density and wave injection geometry that are more similar to those envisaged for CTS in ITER. The upgrades of the diagnostic are presented as well as a few preliminary spectra detected with the new system during the very first operations in 2014. The present work has been carried out under an EUROfusion Enabling Research project. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  4. Physical protection upgrades in Ukraine.

    SciTech Connect

    Djakov, A.

    1998-08-06

    The U.S. DOE is providing nuclear material safeguards assistance in both material control and accountability and in physical protection to several facilities in Ukraine. This paper summarizes the types of physical protection upgrades that have been or are presently being implemented at these facilities. These facilities include the Kiev Institute for Nuclear Research, Kharkov Institute of Physics and Technology, Sevastopol Institute of Nuclear Energy and Industry, and the South Ukraine Nuclear Power Plant. Typical upgrades include: hardening of storage areas; improvements in access control, intrusion detection, and CCTV assessment; central alarm station improvements; and implementation of new voice communication systems. Methods used to implement these upgrades and problems encountered are discussed. Training issues are also discussed.

  5. Status of TMX upgrade diagnostics construction

    SciTech Connect

    Hornady, R.S.; Davis, J.C.; Simonen, T.C.

    1981-07-20

    This report describes the status of the initial TMX Upgrade diagnostics and the state of development of additional diagnostics being prepared for later TMX Upgrade experiments. The initial diagnostic instrument set has been described in the TMX Upgrade Proposal. This set is required to get TMX Upgrade operational and to evaluate its initial performance. Additional diagnostic instruments are needed to then carry out the more detailed experiments outlined by the TMX Upgrade program milestones. The relation of these new measurements to the physics program is described in The TMX Upgrade Program Plan.

  6. NSTX-U Control System Upgrades

    DOE PAGESBeta

    Erickson, K. G.; Gates, D. A.; Gerhardt, S. P.; Lawson, J. E.; Mozulay, R.; Sichta, P.; Tchilinguirian, G. J.

    2014-06-01

    The National Spherical Tokamak Experiment (NSTX) is undergoing a wealth of upgrades (NSTX-U). These upgrades, especially including an elongated pulse length, require broad changes to the control system that has served NSTX well. A new fiber serial Front Panel Data Port input and output (I/O) stream will supersede the aging copper parallel version. Driver support for the new I/O and cyber security concerns require updating the operating system from Redhat Enterprise Linux (RHEL) v4 to RedHawk (based on RHEL) v6. While the basic control system continues to use the General Atomics Plasma Control System (GA PCS), the effort to forwardmore » port the entire software package to run under 64-bit Linux instead of 32-bit Linux included PCS modifications subsequently shared with GA and other PCS users. Software updates focused on three key areas: (1) code modernization through coding standards (C99/C11), (2) code portability and maintainability through use of the GA PCS code generator, and (3) support of 64-bit platforms. Central to the control system upgrade is the use of a complete real time (RT) Linux platform provided by Concurrent Computer Corporation, consisting of a computer (iHawk), an operating system and drivers (RedHawk), and RT tools (NightStar). Strong vendor support coupled with an extensive RT toolset influenced this decision. The new real-time Linux platform, I/O, and software engineering will foster enhanced capability and performance for NSTX-U plasma control.« less

  7. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. Having the inherent capability for combining reaction and separation in a single step, they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, such as these typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. This project will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. Development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  8. 4 MW upgrade to the DIII-D fast wave current drive system

    SciTech Connect

    deGrassie, J.S.; Pinsker, R.I.; Cary, W.P.

    1993-10-01

    The DIII-D fast wave current drive (FWCD) system is being upgraded by an additional 4 MW in the 30 to 120 MHz frequency range. This capability adds to the existing 2 MW 30 to 60 MHz system. Two new ABB transmitters of the type that are in use on the ASDEX-Upgrade tokamak in Garching will be used to drive two new water-cooled four-strap antennas to be installed in DIII-D in early 1994. The transmission and tuning system for each antenna will be similar to that now in use for the first 2 MW system on DIII-D, but with some significant improvements. One improvement consists of adding a decoupler element to counter the mutual coupling between the antenna straps which results in large imbalances in the power to a strap for the usual current drive intrastrap phasing of 90{degrees}. Another improvement is to utilize pressurized, ceramic-insulated transmission lines. The intrastrap phasing will again be controlled in pairs, with a pair of straps coupled in a resonant loop configuration, locking their phase difference at either 0 or 180{degrees}, depending upon the length of line installed. These resonant loops will incorporate a phase shifter so that they will be able to be tuned to resonance at several frequencies in the operating band of the transmitter. With the frequency change capability of the ABB generators, the FWCD frequency will thus be selectable on a shot-to-shot basis, from this preselected set of frequencies. The schedule is for experiments to begin with this added 4 MW capability in mid-1994. The details of the system are described.

  9. Upgrade of the BATMAN test facility for H{sup −} source development

    SciTech Connect

    Heinemann, B. Fröschle, M.; Falter, H.-D.; Fantz, U.; Franzen, P.; Kraus, W.; Nocentini, R.; Riedl, R.; Ruf, B.

    2015-04-08

    The development of a radio frequency (RF) driven source for negative hydrogen ions for the neutral beam heating devices of fusion experiments has been successfully carried out at IPP since 1996 on the test facility BATMAN. The required ITER parameters have been achieved with the prototype source consisting of a cylindrical driver on the back side of a racetrack like expansion chamber. The extraction system, called “Large Area Grid” (LAG) was derived from a positive ion accelerator from ASDEX Upgrade (AUG) using its aperture size (ø 8 mm) and pattern but replacing the first two electrodes and masking down the extraction area to 70 cm2. BATMAN is a well diagnosed and highly flexible test facility which will be kept operational in parallel to the half size ITER source test facility ELISE for further developments to improve the RF efficiency and the beam properties. It is therefore planned to upgrade BATMAN with a new ITER-like grid system (ILG) representing almost one ITER beamlet group, namely 5 × 14 apertures (ø 14 mm). Additionally to the standard three grid extraction system a repeller electrode upstream of the grounded grid can optionally be installed which is positively charged against it by 2 kV. This is designated to affect the onset of the space charge compensation downstream of the grounded grid and to reduce the backstreaming of positive ions from the drift space backwards into the ion source. For magnetic filter field studies a plasma grid current up to 3 kA will be available as well as permanent magnets embedded into a diagnostic flange or in an external magnet frame. Furthermore different source vessels and source configurations are under discussion for BATMAN, e.g. using the AUG type racetrack RF source as driver instead of the circular one or modifying the expansion chamber for a more flexible position of the external magnet frame.

  10. The CEBAF RF Separator System Upgrade

    SciTech Connect

    J. Hovater; Mark Augustine; Al Guerra; Richard Nelson; Robert Terrell; Mark Wissmann

    2004-08-01

    The CEBAF accelerator uses RF deflecting cavities operating at the third sub-harmonic (499 MHz) of the accelerating frequency (1497 MHz) to ''kick'' the electron beam to the experimental halls. The cavities operate in a TEM dipole mode incorporating mode enhancing rods to increase the cavity's transverse shunt impedance [1]. As the accelerators energy has increased from 4 GeV to 6 GeV the RF system, specifically the 1 kW solid-state amplifiers, have become problematic, operating in saturation because of the increased beam energy demands. Two years ago we began a study to look into replacement for the RF amplifiers and decided to use a commercial broadcast Inductive Output Tube (IOT) capable of 30 kW. The new RF system uses one IOT amplifier on multiple cavities as opposed to one amplifier per cavity as was originally used. In addition, the new RF system supports a proposed 12 GeV energy upgrade to CEBAF. We are currently halfway through the upgrade with three IOTs in operation and the remaining one nearly installed. This paper reports on the new RF system and the IOT performance.