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Your search keyword '"Fussmann, G."' showing total 21 results
Start Over Author "Fussmann, G." Journal nuclear fusion
21 results on '"Fussmann, G."'

1. Overview of ASDEX Upgrade results

Author

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

Published
1999
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2. Tungsten as target material in fusion devices

Author

Naujoks, D, primary, Asmussen, K, additional, Bessenrodt-Weberpals, M, additional, Deschka, S, additional, Dux, R, additional, Engelhardt, W, additional, Field, A.R, additional, Fussmann, G, additional, Fuchs, J.C, additional, Garcia-Rosales, C, additional, Hirsch, S, additional, Ignacz, P, additional, Lieder, G, additional, Mast, K.F, additional, Neu, R, additional, Radtke, R, additional, Roth, J, additional, and Wenzel, U, additional

Published
1996
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4. Density limit investigations on ASDEX

Author

Stabler, A, primary, McCormick, K, additional, Mertens, V, additional, Muller, E.R, additional, Neuhauser, J, additional, Niedermeyer, H, additional, Steuer, K.-H, additional, Zohm, H, additional, Dollinger, F, additional, Eberhagen, A, additional, Fussmann, G, additional, Gehre, O, additional, Gernhardt, J, additional, Hartinger, T, additional, Hofmann, J.V, additional, Kakoulidis, E, additional, Kaufmann, M, additional, Kyriakakis, G, additional, Lang, R.S, additional, Murmann, H.D, additional, Poschenrieder, W, additional, Ryter, F, additional, Sandmann, W, additional, Schneider, U, additional, Siller, G, additional, Soldner, F.X, additional, Tsois, N, additional, Vollmer, O, additional, and Wagner, F, additional

Published
1992
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13. Confinement and stability in ASDEX discharges close to the beta limit

Author

Becker, G., Gierke, G.V., Keilhacker, M., Bernhardi, K., Ditte, U., Eberhagen, A., Fussmann, G., Gehre, O., Gernhardt, J., Glock, E., Gruber, O., Haas, G., Hesse, M., Janeschitz, G., Karger, F., Kerner, W., Klober, O., Kornherr, M., Lackner, K., Lisitano, G., Mayer, H.M., Mccormick, K., Meisel, D., Mertens, V., Moller, E.R., Murmann, H., Niedermeyer, H., Poschenrieder, W., Rapp, H., Ryter, F., Schneider, F., Siller, G., Smeulders, P., Söldner, F., Speth, E., Steuer, K.-H., and Vollmer, O.

Abstract

The highest ?-values derived from diamagnetic flux measurements in H-discharges are found to be close to the ?-limit due to kink and ideal ballooning modes. Both energy and particle confinement are degraded in these discharges and do not recover during the injection period. The energy confinement time decreases by a typical factor of two, the electron thermal diffusivity being correspondingly enhanced. Electron heat conduction is again found to be the dominant energy loss channel. The degradation of confinement close to the ideal-MHD limit suggests that kink and ballooning instabilities occur and are responsible for the enhanced transport. This conclusion is supported by the correlation with the pressure profile and by the result that global and local transport do not change in a reference discharge which is stable against ideal-MHD modes.

Published
1985
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14. On the motion of runaway electrons in momentum space

Author

Fussmann, G.

Abstract

The suprathermal drag force and the motion of suprathermal electrons in momentum space are analysed for a multi-component plasma. The calculations of the particle motion are based on the suprathermal Fokker-Planck equation and include relativistic effects. It is found that, owing to pitch angle scattering, the flow patterns in momentum space are more complicated than previously assumed. Simple expressions for the runaway threshold and the perpendicular momentum of relativistic runaways are derived. The acceleration and slowing-down of runaways are also briefly discussed.

Published
1979
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15. Pellet injection with improved confinement in ASDEX

Author

Kaufmann, M., Büchl, K., Fussmann, G., Gehre, O., Grassie, K., Gruber, O., Haas, G., Janeschitz, G., Kornherr, M., Lackner, K., Lang, R.S., Mast, K.F., McCormick, K., Mertens, V., Neuhauser, J., Niedermeyer, H., Sandmann, W., Schneider, W., Zasche, D., Zehrfeld, H.-P., Pietrzyk, Z.A., and Vlases, G.

Abstract

Tokamak discharges with repetitive pellet fuelling were investigated in the ASDEX divertor device. The importance of sufficiently high divertor recycling for a high density at the separatrix and for successful density buildup in the bulk plasma was demonstrated. In contrast to low recycling discharges where no permanent improvement of the energy confinement time was achieved, in OH-heated discharges with high recycling an energy confinement time of 160 ms was reached, the normal value being 80 ms in the rollover region. The peaked density profiles in this case were accompanied by reduced or suppressed sawtooth activity and finally ended in a phase of strong central impurity accumulation. The particle transport was characterized by strong, non-classical inward drift, while the improved energy transport can be explained by the following alternatives: (la) a local model which assumes neo-Alcator ?efor the electrons and ?i= 3?neoclfor the ions in the gas puff cases, reducing to ?i= ?neoclfor the optimum pellet cases; (1b) the assumption ?i= ?neoclunder all conditions and an electron energy confinement worse than neo-Alcator in the rollover region in gas-puff-discharges; (2) a profile consistency picture where Te(a) determines the energy confinement. Low power, NI heated discharges with pellet fuelling behave like Ohmic discharges, while for high power in the L-mode no successful density buildup was possible, and ?Ewas not improved. The H-regime was extended from a density maximum e= 0.8 × 1020m-3without pellets to e= 1.2 × 1020m-3by the injection of pellets. In this case a density buildup takes place, but further density profile peaking could not be observed.

Published
1988
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16. Heating and confinement in the ion cyclotron range of frequencies on the divertor tokamak ASDEX

Author

Steinmetz, K., Niedermeyer, H., Noterdaeme, J.-M., Wagner, F., Wesner, F., Bäumler, J., Becker, G., Becker, W., Bosch, H.S., Brambilla, M., Braun, F., Bracken, H., Dodel, G., Eberhagen, A., Fritsch, R., Fussmann, G., Gehre, O., Gernhardt, J., von Gierke, G., Glock, E., Gruber, O., Haas, G., Hofmann, J., Hofmeister, F., Holzhauer, E., Izvozchikov, A.B., Janeschitz, G., Karger, F., Keilhacker, M., Kislyakov, A., Klüber, O., Kornherr, M., Kotze, P.B., Lackner, K., Lisitano, G., Van Mark, E., Mast, K.F., Mayer, H.-M., McCormick, K., Meisel, D., Mertens, V., Müller, E.R., Murmann, H.D., Neuhauser, J., Pietrzyk, Z.A., Poschenrieder, W., Puri, S., Rapp, H., Roth, J., Rudyj, A., Ryter, F., Schneider, F., Setzensack, C., Siller, G., Smeulders, P., Söll, M., Speth, E., Söldner, F.X., Stäbler, A., Steuer, K.-H., Vollmer, O., Wedler, H., and Zasche, D.

Abstract

The paper summarizes the experiments performed with ion cyclotron resonance heating (ICRH) on ASDEX, from November 1984 until March 1986; the most interesting results are reported and discussed in detail. Heating and confinement studies using the hydrogen second harmonic scheme and the hydrogen minority scheme (PIC< 2.6 MW, tIC< 1.5 s) show a typical L-mode behaviour, i.e. a power dependent confinement degradation, which is rather similar to that found with neutral beam injection (NBI) heating. ICRH is accompanied by a slightly improved particle and energy confinement compared with that of NBI; this is also true for a combined ICRH + NBI scheme, up to Ptot? 4.5 MW, absorbed in the plasma. Particular efforts have been devoted to investigations of the second harmonic regime in H/D plasmas with nH/ne? 0.1 - 1, with a view to heating mixtures in reactor relevant plasmas. The achievement of H-mode transitions with ICRH alone in the hydrogen minority scheme at an absorbed RF power of about 1.1 MW supports the assumption of common confinement properties in auxiliary heated tokamaks, since they appear to be widely independent of the additional heating method. ICRH specific impurity problems, such as the strong release of iron from the vessel walls, have been overcome by applying extensive in situ wall carbonization. The mechanisms responsible for impurity generation have partly been identified and analysed; however, the problem still remains to be solved. Impurities preferentially released from the ICRH antenna do not pose problems.

Published
1989
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17. A study of runaway electron confinement in the ASDEX tokamak

Author

Kwon, O.J., Diamond, P.H., Wagner, F., and Fussmann, G.

Abstract

The results of runaway electron confinement experiments from ASDEX are analysed to elucidate the structure of electromagnetic turbulence which may cause anomalous electron heat transport in the L-mode confinement regime. From a simple model, the radial correlation length (W) of the magnetic turbulence is determined to be about 1 mm. Using this value and that of the experimentally deduced electron thermal diffusivity, the authors determine the radial magnetic fluctuation level at the plasma edge in the L-mode to be (r/B0) ~ 2 × 10?4. Scalings of W and r/B0are deduced from parameter scans. From a comparison of these results with the predictions of various theoretical models, it is concluded that skin depth turbulence, electromagnetic drift wave turbulence, rippling modes, and microtearing modes are inferior candidates and that resistive ballooning modes offer the best possibility for a consistent interpretation of the data.

Published
1988
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18. Evolution of radiation power profiles in ASDEX H-mode discharges

Author

Müller, E.R., Janeschitz, G., Smeulders, P., and Fussmann, G.

Abstract

The paper investigates bolometrically determined radiation power profiles, energy exhaust and impurity accumulation in the two types of H-mode in ASDEX. During the burst dominated H-mode, the repetitive burst-like energy and particle expulsion into the divertor prevents an increase of radiation within the outer half of the plasma minor radius. This type of H-mode arrives at an equilibrium state. During the burst free H-mode, the radiation power losses, unimpeded by bursts, grow over the entire plasma cross-section until this H-mode ends in radiation collapse. Impurity accumulation, resulting in central peaking of the radiation power profiles, takes place in both types of H-mode. The time evolutions of the central radiation power density and the predominantly responsible iron concentration are not significantly affected by the presence or absence of bursts. However, to establish the burst free H-mode, it is required that the absolute values of the iron concentration and the associated radiation power losses at the plasma centre exceed given threshold values. This critical level can be achieved either by external injection of medium-Z metals or by sufficiently strong accumulation of intrinsic metallic impurities during a preceding burst dominated H-phase.

Published
1987
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19. Retention of gaseous and target produced impurities in the ASDEX divertor chamber

Author

Janeschitz, G., Fussmann, G., Kotzé, P.B., Mahdavi, A., Roth, J., Taglauer, E., Bartiromo, R., Becker, G., Bosch, H.S., Eberhagen, A., Gehre, O., Gernhardt, J., Von Gierke, G., Glock, E., Gruber, O., Haas, C., Karger, F., Keilhacker, M., Kislyakov, A., Klüber, O., Kornherr, M., Lenoci, M., Lisitano, G., Mayer, H.-M., McCormick, K., Meisel, D., Mertens, V., Müller, E.R., Murmann, H., Niedermeyer, H., Poschenrieder, W., Rapp, H., Ryter, F., Schneider, F., Siller, G., Smeulders, P., Söldner, F.X., Speth, E., Steinmetz, K., Steuer, K.-H., Vollmer, O., Wagner, F., and Wesner, F.

Abstract

This letter reports on two experiments undertaken to evaluate the retention of gaseous and target produced impurities in the ASDEX divertor. The retention for gaseous impurities was determined by puffing Ar into the main chamber and simulating the time behaviour of the Ar XVI line intensity with a time dependent impurity transport code including a simple divertor model. During Ohmic heating a factor of 3 and 4.5 enhancement of impurity retention if found relative to the vacuum time constant (90 ms) of the divertor chamber, for ne= 2 × 1013cm?3and ne= 3.5 × 1013cm?3, respectively, while a drastic breakdown of the retention occurs during high power NI heating. - To deduce the retention of impurities generated at the divertor plates, a segment (3.5%) of the plates was covered with copper, a metal previously not used in ASDEX. By measuring the Cu influx at the target plates and the line intensity of the Cu XX line (11.38 Å) in the core plasma and by using the transport code, it is found that during NI heating (ne? 2 × 1013cm?3) Cu atoms originating from the target plates have a ? 3.5 times higher probability to penetrate into the core plasma than if they had when originating from the main chamber walls.

Published
1986
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20. Transport simulation of neutral-beam-heated ASDEX plasma in the L and H regimes

Author

Becker, G., primary, Campbell, D., additional, Eberhagen, A., additional, Gehre, O., additional, Gernhardt, J., additional, Lackner, K., additional, Mayer, H.-M., additional, Meisel, D., additional, Murmann, H., additional, Rapp, H., additional, Stäbler, A., additional, Wagner, F., additional, Behringer, K., additional, Fussmann, G., additional, von Gierke, G., additional, Glock, E., additional, Haas, G., additional, Karger, F., additional, Keilhacker, M., additional, Klüber, O., additional, Kornherr, M., additional, Lisitano, G., additional, Lister, G.G., additional, Müller, E.R., additional, Niedermeyer, H., additional, Poschenrieder, W., additional, Röhr, H., additional, Schneider, F., additional, Siller, G., additional, Smeulders, P., additional, Söldner, F., additional, Speth, E., additional, Steinmetz, K., additional, Steuer, K.-H., additional, Szymanski, Z., additional, Venus, G., additional, and Vollmer, O., additional

Published
1983
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