The successful use of a tokamak for generating fusion power requires an active control of magnetic instabilities, such as neoclassical tearing modes (NTMs). Commonly, the NTM location is determined using electron cyclotron emission (ECE) and this is used to apply electron cyclotron heating (ECH) on the NTM location. In this paper, an inline ECE set-up at ASDEX Upgrade is presented in which ECE is measured and ECH is applied via the same path. First results are presented and a means to interpret the measurement data is given. Amplitude and phase with respect to a reference magnetic signal are calculated. Based on the amplitude and phase, the time of mode crossing is determined and shown to compare well with real-time estimates of the mode crossing time. The ECH launcher and [formula]; flux surface geometries at ASDEX Upgrade, which are optimized for current drive by a beam path that is tangential to the flux surface near deposition, make it difficult to identify the mode crossing without inline ECE launcher movement. Therefore, NTM control based on inline ECE requires launcher movement to determine and maintain a reliable estimate of the NTM location.

VL - 59 IS - 1 U1 -FP

U2 -IMM

U5 - 2bc2830faba9c0bb417e0bdddbc5e96e ER - TY - JOUR T1 - TORBEAM 2.0, a paraxial beam tracing code for electron-cyclotron beams in fusion plasmas for extended physics applications JF - Computer Physics Communications Y1 - 2018 A1 - Poli, E. A1 - Bock, A. A1 - Lochbrunner, M. A1 - Maj, O. A1 - Reich, M. A1 - Snicker, A. A1 - Stegmeir, A. A1 - Volpe, F. A1 - Bertelli, N. A1 - Westerhof, E. A1 - Bilato, R. A1 - Conway, G. D. A1 - Farina, D. A1 - Felici, F. A1 - Figini, L. A1 - Fischer, R. A1 - Galperti, C. A1 - Happel, T. A1 - Lin-Liu, Y. R. A1 - Marushchenko, N. B. A1 - U. Mszanowski A1 - Poli, F. M. A1 - Stober, J. A1 - Zille, R. A1 - Peeters, A. G. A1 - Pereverzev, G. V. KW - Electron cyclotron waves KW - Magnetic confinement KW - Paraxial beam tracing KW - Plasma physics KW - Wave-plasma interactions AB -The paraxial WKB code TORBEAM (Poli, 2001) is widely used for the description of electron-cyclotron waves in fusion plasmas, retaining diffraction effects through the solution of a set of ordinary differential equations. With respect to its original form, the code has undergone significant transformations and extensions, in terms of both the physical model and the spectrum of applications. The code has been rewritten in Fortran 90 and transformed into a library, which can be called from within different (not necessarily Fortran-based) workflows. The models for both absorption and current drive have been extended, including e.g. fully-relativistic calculation of the absorption coefficient, momentum conservation in electron–electron collisions and the contribution of more than one harmonic to current drive. The code can be run also for reflectometry applications, with relativistic corrections for the electron mass. Formulas that provide the coupling between the reflected beam and the receiver have been developed. Accelerated versions of the code are available, with the reduced physics goal of inferring the location of maximum absorption (including or not the total driven current) for a given setting of the launcher mirrors. Optionally, plasma volumes within given flux surfaces and corresponding values of minimum and maximum magnetic field can be provided externally to speed up the calculation of full driven-current profiles. These can be employed in real-time control algorithms or for fast data analysis.

VL - 225 U1 -FP

U2 -IMM

U5 - 0a1c01a94caffb41c92a033957ecb032 ER - TY - JOUR T1 - Analysis of electron cyclotron emission with extended electron cyclotron forward modeling JF - Plasma Physics and Controlled Fusion Y1 - 2018 A1 - Denk, S. S. A1 - Fischer, R. A1 - Smith, H. M. A1 - Helander, P. A1 - Maj, O. A1 - Poli, E. A1 - Stober, J. A1 - Stroth, U. A1 - Suttrop, W. A1 - Westerhof, E. A1 - Willensdorfer, M. VL - 60 IS - 10 U1 - FP U2 - IMM U5 - df59365cf1fee065f44d3cc4dc8ce8d2 ER - TY - JOUR T1 - Collective Thomson scattering measurements of fast-ion transport due to sawtooth crashes in ASDEX Upgrade JF - Nuclear Fusion Y1 - 2016 A1 - Rasmussen, J. A1 - Nielsen, S. K. A1 - Stejner, M. A1 - Galdon-Quiroga, J. A1 - M. García-Muñoz A1 - Geiger, B. A1 - Jacobsen, A. S. A1 - Jaulmes, F. A1 - Korsholm, S. B. A1 - Lazanyi, N. A1 - Leipold, F. A1 - Ryter, F. A1 - Salewski, M. A1 - Schubert, M. A1 - Stober, J. A1 - Wagner, D. A1 - ASDEX-Upgrade Team A1 - EUROfusion MST1 Team AB -Sawtooth instabilities can modify heating and current-drive profiles and potentially increase fast-ion losses. Understanding how sawteeth redistribute fast ions as a function of sawtooth parameters and of fast-ion energy and pitch is hence a subject of particular interest for future fusion devices. Here we present the first collective Thomson scattering (CTS) measurements of sawtooth-induced redistribution of fast ions at ASDEX Upgrade. These also represent the first localized fast-ion measurements on the high-field side of this device. The results indicate fast-ion losses in the phase-space measurement volume of about 50% across sawtooth crashes, in good agreement with values predicted with the Kadomtsev sawtooth model implemented in TRANSP and with the sawtooth model in the EBdyna_go code. In contrast to the case of sawteeth, we observe no fast-ion redistribution in the presence of fishbone modes. We highlight how CTS measurements can discriminate between different sawtooth models, in particular when aided by multi-diagnostic velocity-space tomography, and briefly discuss our results in light of existing measurements from other fast-ion diagnostics.

VL - 56 UR - http://www.euro-fusionscipub.org/wp-content/uploads/eurofusion/WPMST1PR16_14817_submitted.pdf IS - 11 U1 -FP

U2 -IMM

U3 - FP120 U5 - eddb183650ee17cb3ca57e0115ea119f ER - TY - JOUR T1 - Development of Resonant Diplexers for high-power ECRH – Status, Applications, Plans JF - EPJ Web of Conferences Y1 - 2015 A1 - Kasparek, W. A1 - Plaum, B. A1 - Lechte, C. A1 - Wu, Z. A1 - Wang, H. A1 - Maraschek, M. A1 - Stober, J. A1 - van den Brand, H. A1 - Bongers, W. A1 - Wagner, D. A1 - Reich, M. A1 - Schubert, M. A1 - Grünwald, G. A1 - Monaco, F. A1 - Müller, S. A1 - Schütz, H. A1 - Erckmann, V. A1 - Doelman, N. A1 - Van den Braber, R. A1 - Klop, W. A1 - Krijger, B. A1 - Petelin, M. A1 - Koposova, E. A1 - Lubyako, L. A1 - Bruschi, A. A1 - Sakamoto, K. A1 - teams at the contributing institutes A1 - ASDEX-Upgrade Team VL - 87 U1 - MaSF U2 - MaSF-E U5 - af697d7f1266e4cb40e18cc68c2ff676 ER - TY - JOUR T1 - Measurements of the fast-ion distribution function at ASDEX upgrade by collective Thomson scattering (CTS) using active and passive views JF - Plasma Physics and Controlled Fusion Y1 - 2015 A1 - Nielsen, S.K. A1 - Stejner, M. A1 - Rasmussen, J. A1 - Jacobsen, A. S. A1 - Korsholm, S. B. A1 - Leipold, F. A1 - Maraschek, M. A1 - Meo, F. A1 - Michelsen, P. K. A1 - Moseev, D. A1 - Salewski, M. A1 - Schubert, M. A1 - Stober, J. A1 - Suttrop, W. A1 - Tardini, G. A1 - Wagner, D. AB - Collective Thomson scattering (CTS) can provide measurements of the confined fast-ion distribution function resolved in space, time and 1D velocity space. On ASDEX Upgrade, the measured spectra include an additional signal which previously has hampered data interpretation. A new set-up using two independent heterodyne receiver systems enables subtraction of the additional part from the total spectrum, revealing the resulting CTS spectrum. Here we present CTS measurements from the plasma centre obtained in L-mode and H-mode plasmas with and without neutral beam injection (NBI). For the first time, the measured spectra agree quantitatively with the synthetic spectra in periods with and without NBI heating. For the discharges investigated, the central velocity distribution of neutral beam ions can be described by classical slowing down. These results will have a major impact on ITER physics exploration, since CTS is presently the only diagnostic to measure the confined alpha particles produced by the fusion reactions. VL - 57 IS - 3 U1 - FP U2 - PDG U5 - 428c8b386186e809125a64e543a5c5b2 ER - TY - JOUR T1 - A Multifrequency Notch Filter for Millimeter Wave Plasma Diagnostics based on Photonic Bandgaps in Corrugated Circular Waveguides JF - EPJ Web of Conferences Y1 - 2015 A1 - Wagner, D. A1 - Bongers, W. A1 - Kasparek, W. A1 - Leuterer, F. A1 - Monaco, F. A1 - M. Münich A1 - Schütz, H. A1 - Stober, J. A1 - Thumm, M. A1 - van de Brand, H. VL - 87 U1 - MaSF U2 - MaSF-E U5 - 26a8cda6694a646ba2b4d3ffdf790250 ER - TY - JOUR T1 - Development of advanced inductive scenarios for ITER JF - Nuclear Fusion Y1 - 2014 A1 - Luce, T. C. A1 - Challis, C. D. A1 - Ide, S. A1 - Joffrin, E. A1 - Kamada, Y. A1 - Polizer, P. A. A1 - Schweinzer, J. A1 - Sips, A.C.C. A1 - Stober, J. A1 - Giruzzi, G. A1 - Kessel, C. E. A1 - Murakami, M. A1 - Na, Y.-S. A1 - Park, J. M. A1 - Polevoi, A. R. A1 - Budny, R. V. A1 - Citrin, J. A1 - Garcia, J. A1 - Hayashi, N. A1 - Hobirk, J. A1 - Hudson, B. F. A1 - Imbeaux, F. A1 - Isayama, A. A1 - McDonald, D. C. A1 - Nakano, T. A1 - Oyama, N. A1 - Parail, V.V. A1 - Petrie, T. W. A1 - Petty, C. C. A1 - Suzuki, T. A1 - Wade, M. R. AB -Since its inception in 2002, the International Tokamak Physics Activity topical group on Integrated Operational Scenarios (IOS) has coordinated experimental and modelling activity on the development of advanced inductive scenarios for applications in the ITER tokamak. The physics basis and the prospects for applications in ITER have been advanced significantly during that time, especially with respect to experimental results. The principal findings of this research activity are as follows. Inductive scenarios capable of higher normalized pressure (beta(N)>= 2.4) than the ITER baseline scenario (beta(N) = 1.8) with normalized confinement at or above the standard H-mode scaling are well established under stationary conditions on the four largest diverted tokamaks (AUG, DIII-D, JET, JT-60U), demonstrated in a database of more than 500 plasmas from these tokamaks analysed here. The parameter range where high performance is achieved is broad in q(95) and density normalized to the empirical density limit. MHD modes can play a key role in reaching stationary high performance, but also define the limits to achieved stability and confinement. Projection of performance in ITER from existing experiments uses empirical scalings and theory-based modelling. The status of the experimental validation of both approaches is summarized here. The database shows significant variation in the energy confinement normalized to standard H-mode confinement scalings, indicating the possible influence of additional physics variables absent from the scalings. Tests using the available information on rotation and the ratio of the electron and ion temperatures indicate neither of these variables in isolation can explain the variation in normalized confinement observed. Trends in the normalized confinement with the two dimensionless parameters that vary most from present-day experiments to ITER, gyroradius and collision frequency, are significant. Regression analysis on the multi-tokamak database has been performed, but it appears that the database is not conditioned sufficiently well to yield a new scaling for this type of plasma. Coordinated experiments on size scaling using the dimensionless parameter scaling approach find a weaker scaling with normalized gyroradius than the standard H-mode scaling. Preliminary studies on scaling with collision frequency show a favourable scaling stronger than the standard H-mode scaling. Coordinated modelling activity has resulted in successful benchmarking of modelling codes in the ITER regime. Validation of transport models using these codes on present-day experiments is in progress, but no single model has been shown to capture the variations seen in the experiments. However, projection to ITER using these models is in general agreement with the favourable projections found with the empirical scalings.

VL - 54 SN - 0029-5515 IS - 1 U1 -FP

U2 -CPP-HT

U5 - bd8e6e10ad1da6f54b5c768c2cad759e ER - TY - JOUR T1 - Overview of ASDEX Upgrade results JF - Nuclear Fusion Y1 - 2013 A1 - Stroth, U. A1 - Adamek, J. A1 - Aho-Mantila, L. A1 - Akaslompolo, S. A1 - Amdor, C. A1 - Angioni, C. A1 - Balden, M. A1 - Bardin, S. A1 - L. Barrera Orte A1 - Behler, K. A1 - Belonohy, E. A1 - Bergmann, A. A1 - Bernert, M. A1 - Bilato, R. A1 - Birkenmeier, G. A1 - Bobkov, V. A1 - Boom, J. A1 - Bottereau, C. A1 - Bottino, A. A1 - Braun, F. A1 - Brezinsek, S. A1 - Brochard, T. A1 - M. Brüdgam A1 - Buhler, A. A1 - Burckhart, A. A1 - Casson, F. J. A1 - Chankin, A. A1 - Chapman, I. A1 - Clairet, F. A1 - Classen, I.G.J. A1 - Coenen, J. W. A1 - Conway, G. D. A1 - Coster, D. P. A1 - Curran, D. A1 - da Silva, F. A1 - P. de Marné A1 - D'Inca, R. A1 - Douai, D. A1 - Drube, R. A1 - Dunne, M. A1 - Dux, R. A1 - Eich, T. A1 - Eixenberger, H. A1 - Endstrasser, N. A1 - Engelhardt, K. A1 - Esposito, B. A1 - Fable, E. A1 - Fischer, R. A1 - H. Fünfgelder A1 - Fuchs, J. C. A1 - K. Gál A1 - M. García Muñoz A1 - Geiger, B. A1 - Giannone, L. A1 - T. Görler A1 - da Graca, S. A1 - Greuner, H. A1 - Gruber, O. A1 - Gude, A. A1 - Guimarais, L. A1 - S. Günter A1 - Haas, G. A1 - Hakola, A. H. A1 - Hangan, D. A1 - Happel, T. A1 - T. Härtl A1 - Hauff, T. A1 - Heinemann, B. A1 - Herrmann, A. A1 - Hobirk, J. A1 - H. Höhnle A1 - M. Hölzl A1 - Hopf, C. A1 - Houben, A. A1 - Igochine, V. A1 - Ionita, C. A1 - Janzer, A. A1 - Jenko, F. A1 - Kantor, M. A1 - C.-P. Käsemann A1 - Kallenbach, A. A1 - S. Kálvin A1 - Kantor, M. A1 - Kappatou, A. A1 - Kardaun, O. A1 - Kasparek, W. A1 - Kaufmann, M. A1 - Kirk, A. A1 - H.-J. Klingshirn A1 - Kocan, M. A1 - Kocsis, G. A1 - Konz, C. A1 - Koslowski, R. A1 - Krieger, K. A1 - Kubic, M. A1 - Kurki-Suonio, T. A1 - Kurzan, B. A1 - Lackner, K. A1 - Lang, P. T. A1 - Lauber, P. A1 - Laux, M. A1 - Lazaros, A. A1 - Leipold, F. A1 - Leuterer, F. A1 - Lindig, S. A1 - Lisgo, S. A1 - Lohs, A. A1 - Lunt, T. A1 - Maier, H. A1 - Makkonen, T. A1 - Mank, K. A1 - M.-E. Manso A1 - Maraschek, M. A1 - Mayer, M. A1 - McCarthy, P. J. A1 - McDermott, R. A1 - Mehlmann, F. A1 - Meister, H. A1 - Menchero, L. A1 - Meo, F. A1 - Merkel, P. A1 - Merkel, R. A1 - Mertens, V. A1 - Merz, F. A1 - Mlynek, A. A1 - Monaco, F. A1 - Müller, S. A1 - H.W. Müller A1 - M. Münich A1 - Neu, G. A1 - Neu, R. A1 - Neuwirth, D. A1 - Nocente, M. A1 - Nold, B. A1 - Noterdaeme, J. M. A1 - Pautasso, G. A1 - Pereverzev, G. A1 - B. Plöckl A1 - Podoba, Y. A1 - Pompon, F. A1 - Poli, E. A1 - Polozhiy, K. A1 - Potzel, S. A1 - Puschel, M. J. A1 - Putterich, T. A1 - Rathgeber, S. K. A1 - Raupp, G. A1 - Reich, M. A1 - Reimold, F. A1 - Ribeiro, T. A1 - Riedl, R. A1 - Rohde, V. A1 - van Rooij, G. J. A1 - Roth, J. A1 - Rott, M. A1 - Ryter, F. A1 - Salewski, M. A1 - Santos, J. A1 - Sauter, P. A1 - Scarabosio, A. A1 - Schall, G. A1 - Schmid, K. A1 - Schneider, P. A. A1 - Schneider, W. A1 - Schrittwieser, R. A1 - Schubert, M. A1 - Schweinzer, J. A1 - Scott, B. A1 - Sempf, M. A1 - Sertoli, M. A1 - Siccinio, M. A1 - Sieglin, B. A1 - Sigalov, A. A1 - Silva, A. A1 - Sommer, F. A1 - A. Stäbler A1 - Stober, J. A1 - Streibl, B. A1 - Strumberger, E. A1 - Sugiyama, K. A1 - Suttrop, W. A1 - Tala, T. A1 - Tardini, G. A1 - Teschke, M. A1 - Tichmann, C. A1 - Told, D. A1 - Treutterer, W. A1 - Tsalas, M. A1 - VanZeeland, M. A. A1 - Varela, P. A1 - Veres, G. A1 - Vicente, J. A1 - Vianello, N. A1 - Vierle, T. A1 - Viezzer, E. A1 - Viola, B. A1 - Vorpahl, C. A1 - Wachowski, M. A1 - Wagner, D. A1 - Wauters, T. A1 - Weller, A. A1 - Wenninger, R. A1 - Wieland, B. A1 - Willensdorfer, M. A1 - Wischmeier, M. A1 - Wolfrum, E. A1 - E. Würsching A1 - Yu, Q. A1 - Zammuto, I. A1 - Zasche, D. A1 - Zehetbauer, T. A1 - Zhang, Y. A1 - Zilker, M. A1 - Zohm, H. AB - The medium size divertor tokamak ASDEX Upgrade (major and minor radii 1.65 m and 0.5 m, respectively, magnetic-field strength 2.5 T) possesses flexible shaping and versatile heating and current drive systems. Recently the technical capabilities were extended by increasing the electron cyclotron resonance heating (ECRH) power, by installing 2 × 8 internal magnetic perturbation coils, and by improving the ion cyclotron range of frequency compatibility with the tungsten wall. With the perturbation coils, reliable suppression of large type-I edge localized modes (ELMs) could be demonstrated in a wide operational window, which opens up above a critical plasma pedestal density. The pellet fuelling efficiency was observed to increase which gives access to H-mode discharges with peaked density profiles at line densities clearly exceeding the empirical Greenwald limit. Owing to the increased ECRH power of 4 MW, H-mode discharges could be studied in regimes with dominant electron heating and low plasma rotation velocities, i.e. under conditions particularly relevant for ITER. The ion-pressure gradient and the neoclassical radial electric field emerge as key parameters for the transition. Using the total simultaneously available heating power of 23 MW, high performance discharges have been carried out where feed-back controlled radiative cooling in the core and the divertor allowed the divertor peak power loads to be maintained below 5 MW m −2 . Under attached divertor conditions, a multi-device scaling expression for the power-decay length was obtained which is independent of major radius and decreases with magnetic field resulting in a decay length of 1 mm for ITER. At higher densities and under partially detached conditions, however, a broadening of the decay length is observed. In discharges with density ramps up to the density limit, the divertor plasma shows a complex behaviour with a localized high-density region in the inner divertor before the outer divertor detaches. Turbulent transport is studied in the core and the scrape-off layer (SOL). Discharges over a wide parameter range exhibit a close link between core momentum and density transport. Consistent with gyro-kinetic calculations, the density gradient at half plasma radius determines the momentum transport through residual stress and thus the central toroidal rotation. In the SOL a close comparison of probe data with a gyro-fluid code showed excellent agreement and points to the dominance of drift waves. Intermittent structures from ELMs and from turbulence are shown to have high ion temperatures even at large distances outside the separatrix. VL - 53 UR - http://hdl.handle.net/11858/00-001M-0000-0026-E166-7 IS - 10 U1 - FP U2 - PDG U5 - 0b5b08fdc590c85cc01e6d1db1958848 ER - TY - JOUR T1 - Overview on plasma operation with a full tungsten wall in ASDEX Upgrade JF - Journal of Nuclear Materials Y1 - 2013 A1 - Neu, R. A1 - Kallenbach, A. A1 - Balden, M. A1 - Bobkov, V. A1 - Coenen, J. W. A1 - Drube, R. A1 - Dux, R. A1 - Greuner, H. A1 - Herrmann, A. A1 - Hobirk, J. A1 - H. Höhnle A1 - Krieger, K. A1 - M. Kočan A1 - Lang, P. A1 - Lunt, T. A1 - Maier, H. A1 - Mayer, M. A1 - H.W. Müller A1 - Potzel, S. A1 - Putterich, T. A1 - Rapp, J. A1 - Rohde, V. A1 - Ryter, F. A1 - Schneider, P. A. A1 - Schweinzer, J. A1 - Sertoli, M. A1 - Stober, J. A1 - Suttrop, W. A1 - Sugiyama, K. A1 - van Rooij, G. J. A1 - Wischmeier, M. AB - Abstract Operation with all tungsten plasma facing components has become routine in ASDEX Upgrade. The conditioning of the device is strongly simplified and short glow discharges are used only on a daily basis. The long term fuel retention was reduced by more than a factor of 5 as demonstrated in gas balance as well as in post mortem analyses. Injecting nitrogen for radiative cooling, discharges with additional heating power up to 23 MW have been achieved, providing good confinement (H98y2=1), divertor power loads around 5 MW m−2 and divertor temperatures below 10 eV. ELM mitigation by pellet ELM pacemaking or magnetic perturbation coils reduces the deposited energy during ELMs, but also keeps the W density at the pedestal low. As a recipe to keep the central W concentration sufficiently low, central (wave) heating is well established and low density H-Modes could be re-established with the newly available ECRH power of up to 4 MW. The ICRH induced W sources could be strongly reduced by applying boron coatings to the poloidal guard limiters. VL - 438, Supplement UR - http://www.sciencedirect.com/science/article/pii/S0022311513000147 N1 -Hybrid scenarios in present machines are often characterized by improved confinement compared with the IPB98(y, 2) empirical scaling law expectations. This work concentrates on isolating the impact of increased s/q at outer radii (where s is the magnetic shear) on core confinement in low-triangularity JET and ASDEX Upgrade (AUG) experiments. This is carried out by predictive heat and particle transport modelling using the integrated modelling code CRONOS coupled to the GLF23 turbulent transport model. For both machines, discharge pairs were analysed displaying similar pedestal confinement yet significant differences in core confinement. From these comparisons, it is found that s/q shaping at outer radii may be responsible for up to similar to 50% of the relative core confinement improvement observed in these specific discharges. This relative improvement is independent of the degree of rotational shear turbulence suppression assumed in the GLF23 model. However, employing the full GLF23 rotational shear model leads to an overprediction of the ion temperatures in all discharges analysed. Additional mechanisms for core confinement improvement are discussed and estimated. Further linear threshold analysis with QuaLiKiz is carried out on both pairs of discharges. This work aims to validate recent predictions of the ITER hybrid scenario also employing CRONOS/GLF23, where a high level of confinement and resultant fusion power sensitivity to the s/q profile was found.

VL - 54 SN - 0741-3335 N1 - ISI Document Delivery No.: 947PATimes Cited: 0Cited Reference Count: 56 U1 -FP

U2 -CPP-HT

U5 - bda1f42e30092cecb77d13ab81a2b6af ER - TY - JOUR T1 - Characterization of Alfvén eigenmodes using NBI during current ramp-up in the ASDEX Upgrade tokamak JF - Plasma Physics and Controlled Fusion Y1 - 2012 A1 - S da Graça A1 - Conway, G. D. A1 - Lauber, P. A1 - Curran, D. A1 - Igochine, V. A1 - Classen, I.G.J. A1 - M. García-Muñoz A1 - Stober, J. A1 - VanZeeland, M. A. A1 - Manso, M. E. AB - Alfvén cascades (ACs) and beta-induced Alfvén eigenmodes (BAEs) have been studied in the ASDEX Upgrade tokamak during the current ramp-up phase of neutral beam heated (NBI) discharges using principally reflectometry, but also soft x-ray (SXR) and electron cyclotron emission imaging (ECEI). ACs have been observed on the tokamak high-field side and low-field side in reflectometer signals even in the absence of a cutoff. Under this condition it is shown that the response is not due to an interferometry effect but due to backscatter. The radial structure of BAEs and ACs has been obtained by cross-correlating the reflectometer with SXR, ECEI and magnetic signals. The reflectometer signals reveal a variety of Alfvén eigenmodes with different characteristics depending on the plasma heating scheme. Here, discharges with similar plasma parameters but varying NBI sources and/or additional electron cyclotron resonance heating were performed. It is shown that the bursting behaviour of ACs for q min < 2 depends on the NBI beam geometry. Also, a discrepancy in the n = 2 AC minimum frequency of a Grand Cascade is explained by the linear gyro-kinetic code LIGKA simulations which include energetic particle effects. VL - 54 UR - http://stacks.iop.org/0741-3335/54/i=9/a=095014 U1 - FP U2 - PDG U5 - f252dfc64095e13179480c9a2754f96c ER - TY - CONF T1 - Controlled Mirror Motion System for Resonant Diplexers in ECRH Applications T2 - EPJ Web of Conferences Y1 - 2012 A1 - Doelman, N. J. A1 - Van den Braber, R. A1 - Kasparek, W. A1 - Erckmann, V. A1 - Bongers, W. A. A1 - Krijger, B. A1 - Stober, J. A1 - Fritz, E. A1 - Dekker, B. A1 - Klop, W. A1 - Hollmann, F. A1 - Michel, G. A1 - Noke, F. A1 - Purps, F. A1 - M.R. de Baar A1 - Maraschek, M. A1 - Monaco, F. A1 - Müller, S. A1 - Schütz, H. A1 - Wagner, D. JF - EPJ Web of Conferences VL - 32 U1 - FP U2 - TP U5 - 2e56b521157cdd6a8067e9e2abc8475a ER - TY - CONF T1 - Status of resonant diplexer development for high-power ECRH applications T2 - EPJ Web of Conferences Y1 - 2012 A1 - Kasparek, W. A1 - Plaum, B. A1 - Lechte, C. A1 - Filipovic, E. A1 - Erckmann, V. A1 - Grünwald, G. A1 - Hollmann, F. A1 - Maraschek, M. A1 - Michel, G. A1 - Monaco, F. A1 - Müller, S. A1 - Noke, F. A1 - Purps, F. A1 - Schubert, M. A1 - Schütz, H. A1 - Stober, J. A1 - Wagner, D. A1 - Van den Braber, R. A1 - Doelman, N. J. A1 - Fritz, E. A1 - Bongers, W. A. A1 - Krijger, B. A1 - Petelin, M. A1 - Lubyako, L. A1 - Bruschi, A. A1 - Sakamoto, K. JF - EPJ Web of Conferences VL - 32 U1 - FP U2 - TP U5 - 035f34446654fa626a865edaeab4feb5 ER - TY - JOUR T1 - Overview of ASDEX Upgrade results JF - Nuclear Fusion Y1 - 2011 A1 - Kallenbach, A. A1 - Adamek, J. A1 - Aho-Mantila, L. A1 - Akaslompolo, S. A1 - Angioni, C. A1 - Atanasiu, C. V. A1 - Balden, M. A1 - Behler, K. A1 - Belonohy, E. A1 - Bergmann, A. A1 - Bernert, M. A1 - Bilato, R. A1 - Bobkov, V. A1 - Boom, J. A1 - Bottino, A. A1 - Braun, F. A1 - Brudgam, M. A1 - Buhler, A. A1 - Burckhart, A. A1 - Chankin, A. A1 - Classen, I.G.J. A1 - Conway, G. D. A1 - Coster, D. P. A1 - de Marne, P. A1 - D'Inca, R. A1 - Drube, R. A1 - Dux, R. A1 - Eich, T. A1 - Endstrasser, N. A1 - Engelhardt, K. A1 - Esposito, B. A1 - Fable, E. A1 - Fahrbach, H. U. A1 - Fattorini, L. A1 - Fischer, R. A1 - Flaws, A. A1 - Funfgelder, H. A1 - Fuchs, J. C. A1 - Gal, K. A1 - Munoz, M. G. A1 - Geiger, B. A1 - Adamov, M. G. A1 - Giannone, L. A1 - Giroud, C. A1 - Gorler, T. A1 - da Graca, S. A1 - Greuner, H. A1 - Gruber, O. A1 - Gude, A. A1 - Gunter, S. A1 - Haas, G. A1 - Hakola, A. H. A1 - Hangan, D. A1 - Happel, T. A1 - Hauff, T. A1 - Heinemann, B. A1 - Herrmann, A. A1 - Hicks, N. A1 - Hobirk, J. A1 - Hohnle, H. A1 - Holzl, M. A1 - Hopf, C. A1 - Horton, L. A1 - Huart, M. A1 - Igochine, V. A1 - Ionita, C. A1 - Janzer, A. A1 - Jenko, F. A1 - Kasemann, C. P. A1 - Kalvin, S. A1 - Kardaun, O. A1 - Kaufmann, M. A1 - Kirk, A. A1 - Klingshirn, H. J. A1 - Kocan, M. A1 - Kocsis, G. A1 - Kollotzek, H. A1 - Konz, C. A1 - Koslowski, R. A1 - Krieger, K. A1 - Kurki-Suonio, T. A1 - Kurzan, B. A1 - Lackner, K. A1 - Lang, P. T. A1 - Lauber, P. A1 - Laux, M. A1 - Leipold, F. A1 - Leuterer, F. A1 - Lohs, A. A1 - N C Luhmann Jr. A1 - Lunt, T. A1 - Lyssoivan, A. A1 - Maier, H. A1 - Maggi, C. A1 - Mank, K. A1 - Manso, M. E. A1 - Maraschek, M. A1 - Martin, P. A1 - Mayer, M. A1 - McCarthy, P. J. A1 - McDermott, R. A1 - Meister, H. A1 - Menchero, L. A1 - Meo, F. A1 - Merkel, P. A1 - Merkel, R. A1 - Mertens, V. A1 - Merz, F. A1 - Mlynek, A. A1 - Monaco, F. A1 - Muller, H. W. A1 - Munich, M. A1 - Murmann, H. A1 - Neu, G. A1 - Neu, R. A1 - Nold, B. A1 - Noterdaeme, J. M. A1 - Park, H. K. A1 - Pautasso, G. A1 - Pereverzev, G. A1 - Podoba, Y. A1 - Pompon, F. A1 - Poli, E. A1 - Polochiy, K. A1 - Potzel, S. A1 - Prechtl, M. A1 - Puschel, M. J. A1 - Putterich, T. A1 - Rathgeber, S. K. A1 - Raupp, G. A1 - Reich, M. A1 - Reiter, B. A1 - Ribeiro, T. A1 - Riedl, R. A1 - Rohde, V. A1 - Roth, J. A1 - Rott, M. A1 - Ryter, F. A1 - Sandmann, W. A1 - Santos, J. A1 - Sassenberg, K. A1 - Sauter, P. A1 - Scarabosio, A. A1 - Schall, G. A1 - Schmid, K. A1 - Schneider, P. A. A1 - Schneider, W. A1 - Schramm, G. A1 - Schrittwieser, R. A1 - Schweinzer, J. A1 - Scott, B. A1 - Sempf, M. A1 - Serra, F. A1 - Sertoli, M. A1 - Siccinio, M. A1 - Sigalov, A. A1 - Silva, A. A1 - Sips, A.C.C. A1 - Sommer, F. A1 - Stabler, A. A1 - Stober, J. A1 - Streibl, B. A1 - Strumberger, E. A1 - Sugiyama, K. A1 - Suttrop, W. A1 - Szepesi, T. A1 - Tardini, G. A1 - Tichmann, C. A1 - Told, D. A1 - Treutterer, W. A1 - Urso, L. A1 - Varela, P. A1 - Vincente, J. A1 - Vianello, N. A1 - Vierle, T. A1 - Viezzer, E. A1 - Vorpahl, C. A1 - Wagner, D. A1 - Weller, A. A1 - Wenninger, R. A1 - Wieland, B. A1 - Wigger, C. A1 - Willensdorfer, M. A1 - Wischmeier, M. A1 - Wolfrum, E. A1 - Wursching, E. A1 - Yadikin, D. A1 - Yu, Q. A1 - Zammuto, I. A1 - Zasche, D. A1 - Zehetbauer, T. A1 - Zhang, Y. A1 - Zilker, M. A1 - Zohm, H. KW - PHYSICS KW - REFLECTOMETRY KW - TOKAMAK AB - The ASDEX Upgrade programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. After the finalization of the tungsten coating of the plasma facing components, the re-availability of all flywheel-generators allowed high-power operation with up to 20 MW heating power at I(p) up to 1.2 MA. Implementation of alternative ECRH schemes (140 GHz O2- and X3-mode) facilitated central heating above n(e) = 1.2 x 10(20) m(-3) and low q(95) operation at B(t) = 1.8 T. Central O2-mode heating was successfully used in high P/R discharges with 20 MW total heating power and divertor load control with nitrogen seeding. Improved energy confinement is obtained with nitrogen seeding both for type-I and type-III ELMy conditions. The main contributor is increased plasma temperature, no significant changes in the density profile have been observed. This behaviour may be explained by higher pedestal temperatures caused by ion dilution in combination with a pressure limited pedestal and hollow nitrogen profiles. Core particle transport simulations with gyrokinetic calculations have been benchmarked by dedicated discharges using variations of the ECRH deposition location. The reaction of normalized electron density gradients to variations of temperature gradients and the T(e)/T(i) ratio could be well reproduced. Doppler reflectometry studies at the L-H transition allowed the disentanglement of the interplay between the oscillatory geodesic acoustic modes, turbulent fluctuations and the mean equilibrium E x B flow in the edge negative E(r) well region just inside the separatrix. Improved pedestal diagnostics revealed also a refined picture of the pedestal transport in the fully developed H-mode type-I ELM cycle. Impurity ion transport turned out to be neoclassical in between ELMs. Electron and energy transport remain anomalous, but exhibit different recovery time scales after an ELM. After recovery of the pre-ELM profiles, strong fluctuations develop in the gradients of n(e) and T(e). The occurrence of the next ELM cannot be explained by the local current diffusion time scale, since this turns out to be too short. Fast ion losses induced by shear Alfven eigenmodes have been investigated by time-resolved energy and pitch angle measurements. This allowed the separation of the convective and diffusive loss mechanisms. VL - 51 SN - 0029-5515 IS - 9 N1 - ISI Document Delivery No.: 818DPTimes Cited: 1Cited Reference Count: 45SI U1 - FP U2 - PDG U5 - a193177a90d5b600862ca1e40bcc67af ER - TY - JOUR T1 - Magnetic island localization for NTM control by ECE viewed along the same optical path of the ECCD beam JF - Fusion Science and Technology Y1 - 2009 A1 - Bongers, W. A. A1 - Goede, A. P. H. A1 - Westerhof, E. A1 - Oosterbeek, J. W. A1 - Doelman, N. J. A1 - Schüller, F. C. A1 - M.R. de Baar A1 - Kasparek, W. A1 - Wubie, W. A1 - Wagner, D. A1 - Stober, J. KW - ASDEX UPGRADE KW - CURRENT DRIVE KW - DESIGN KW - DISCHARGES KW - ECHR/ECCD KW - ELECTRON-CYCLOTRON WAVES KW - feedback control KW - FEEDBACK-SYSTEM KW - GUIDES KW - INSTABILITIES KW - NEOCLASSICAL TEARING MODE KW - NTM stabilization KW - STABILIZATION AB - Neoclassical tearing modes (NTMs) deteriorate high-pressure tokamak plasma confinement and can be suppressed by electron cyclotron current drive (ECCD). In order to obtain efficient suppression, the ECCD power needs to be deposited at the center of an NTM magnetic island. To enhance efficiency, this power also needs to be synchronized in phase with the rotation of the island. The problem is that of real-time detection and precise localization of the island(s) in order to provide the feedback signal required to control the ECCD power deposition area with an accuracy of 1 to 2 cm. Existing schemes based on mode location, equilibrium reconstruction, and plasma profile measurements are limited in positional and temporal accuracy and moreover will become very complex when applied to ITER. To overcome these limitations, it is proposed to provide the feedback signal from electron cyclotron emission (ECE) measurements taken along the identical line of sight as traced by the incident ECCD millimeter-wave beam but in reverse direction. Experiments on TEXTOR have demonstrated a proof of principle. These measurements motivate the further development and the implementation of such an ECCD-aligned ECE system for NTM control in larger fusion machines. Possible implementation of such a system on ASDEX-Upgrade, based on waveguides equipped with a fast directional switch, is presented in this paper. Possible further development for ITER is also discussed. VL - 55 SN - 1536-1055 UR -