Ghent University Academic Bibliography

Advanced

Recent ASDEX upgrade research in support of ITER and DEMO

H Zohm, J Ahn, L Aho-Mantila, S Auml;kaslompolo, C Angioni, O Asunta, M de Baar, M Balden, LB Orte, K Behler, et al. (2015) NUCLEAR FUSION. 55(10).
abstract
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 (nu(*)(ped) < 0.4). In contrast to the previous high nu* 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 P-LH 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/L-Te 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 mass as needed for runaway electron suppression. Large locked modes can significantly decrease the fuelling efficiency and increase the asymmetry of radiated power during MGI mitigation. Concerning power exhaust, the partially detached ITER divertor scenario has been demonstrated at P-sep/R = 10 MW m(-1) in ASDEX Upgrade, with a peak time averaged target load around 5 MW m(-2), well consistent with the component limits for ITER. Developing this towards DEMO, full detachment was achieved at P-sep/R = 7 MW m(-1) and stationary discharges with core radiation fraction of the order of DEMO requirements (70% instead of the 30% needed for ITER) were demonstrated. Finally, it remains difficult to establish the standard ITER Q = 10 scenario at low q(95) = 3 in the all-tungsten (all-W) ASDEX Upgrade due to the observed poor confinement at low beta(N). This is mainly due to a degraded pedestal performance and hence investigations at shifting the operational point to higher beta(N) by lowering the current have been started. At higher q(95), pedestal performance can be recovered by seeding N-2 as well as CD4, which is interpreted as improved pedestal stability due to the decrease of bootstrap current with increasing Z(eff). Concerning advanced scenarios, the upgrade of ECRH power has allowed experiments with central ctr-ECCD to modify the q-profile in improved H-mode scenarios, showing an increase in confinement at still good MHD stability with flat elevated q-profiles at values between 1.5 and 2.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
tokamak physics, nuclear fusion, ITER, DEMO
journal title
NUCLEAR FUSION
Nucl. Fusion
volume
55
issue
10
article number
104010
pages
12 pages
publisher
IOP PUBLISHING LTD
place of publication
BRISTOL
conference name
25th Fusion Energy Conference (FEC)
conference location
Govt Russian Federat, St Petersburg, RUSSIA
conference start
2014-10-13
conference end
2014-10-18
Web of Science type
Article; Proceedings Paper
Web of Science id
000363762900011
JCR category
PHYSICS, FLUIDS & PLASMAS
JCR impact factor
4.04 (2015)
JCR rank
2/30 (2015)
JCR quartile
1 (2015)
ISSN
0029-5515
DOI
10.1088/0029-5515/55/10/104010
language
English
UGent publication?
no
classification
A1
id
7106762
handle
http://hdl.handle.net/1854/LU-7106762
date created
2016-03-01 09:52:40
date last changed
2017-01-02 09:55:17
@article{7106762,
  abstract     = {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 (nu(*)(ped) {\textlangle} 0.4). In contrast to the previous high nu* 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 P-LH 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/L-Te 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 mass as needed for runaway electron suppression. Large locked modes can significantly decrease the fuelling efficiency and increase the asymmetry of radiated power during MGI mitigation. Concerning power exhaust, the partially detached ITER divertor scenario has been demonstrated at P-sep/R = 10 MW m(-1) in ASDEX Upgrade, with a peak time averaged target load around 5 MW m(-2), well consistent with the component limits for ITER. Developing this towards DEMO, full detachment was achieved at P-sep/R = 7 MW m(-1) and stationary discharges with core radiation fraction of the order of DEMO requirements (70\% instead of the 30\% needed for ITER) were demonstrated. Finally, it remains difficult to establish the standard ITER Q = 10 scenario at low q(95) = 3 in the all-tungsten (all-W) ASDEX Upgrade due to the observed poor confinement at low beta(N). This is mainly due to a degraded pedestal performance and hence investigations at shifting the operational point to higher beta(N) by lowering the current have been started. At higher q(95), pedestal performance can be recovered by seeding N-2 as well as CD4, which is interpreted as improved pedestal stability due to the decrease of bootstrap current with increasing Z(eff). 

Concerning advanced scenarios, the upgrade of ECRH power has allowed experiments with central ctr-ECCD to modify the q-profile in improved H-mode scenarios, showing an increase in confinement at still good MHD stability with flat elevated q-profiles at values between 1.5 and 2.},
  articleno    = {104010},
  author       = {Zohm, H and Ahn, J and Aho-Mantila, L and Auml;kaslompolo, S and Angioni, C and Asunta, O and de Baar, M and Balden, M and Orte, LB and Behler, K and Belapure, J and Bergmann, A and Bernardo, J and Bernert, M and Beurskens, M and Biancalani, A and Bilato, R and Birkenmeier, G and Bobkov, V and Bock, A and Bogomolov, A and Bolzonella, T and Boom, J and Boswirth, B and Bottereau, C and Bottino, A and van den Brand, H and Braun, F and Brezinsek, S and Brochard, F and Buhler, A and Burckhart, A and Camenen, Y and Carvalho, P and Carrasco, G and Cazzaniga, C and Carralero, D and Casali, L and Cavedon, M and Challis, C and Chankin, A and Chapman, I and Clairet, F and Classen, I and Coda, S and Coelho, R and Coenen, JW and Colas, L and Conway, G and Costea, S and Coster, DP and Croci, G and Cseh, G and Czarnecka, A and Day, C and de Marne, P and Denner, P and D'Inca, R and Douai, D and Drube, R and Dunne, M and Duval, BP and Dux, R and Eich, T and Elgeti, S and Engelhardt, K and Ertl, K and Esposito, B and Fable, E and Fantz, U and Faugel, H and Felici, F and Fietz, S and Figueredo, A and Fischer, R and Ford, O and Franzen, P and Frassinetti, L and Froschle, M and Fuchert, G and Funfgelder, H and Fuchs, JC and Gal, K and Garavaglia, S and Garcia-Munoz, M and Geiger, B and Giannone, L and Giovannozzi, E and Gleason-Gonzalez, C and Gorler, T and Goodman, T and Gorini, G and da Graca, S and Grater, A and Granucci, G and Greuner, H and Griesshammer, J and Groth, M and Gude, A and Gunter, S and Guimarais, L and Haas, G and Hakola, AH and Happel, T and Harrison, J and Hatch, D and Hauer, V and Hauff, T and Heinemann, B and Heinzel, S and Hellsten, T and Hennequin, P and Herrmann, A and Heyn, E and Hobirk, J and Holzl, M and Hoschen, T and Holm, JH and Hopf, C and Hoppe, F and Horvath, L and Houben, A and Huber, A and Igochine, V and Ilkei, T and Jacob, W and Jacobsen, AS and Jacquot, J and Janzer, M and Jaulmes, F and Jenko, F and Jensen, T and Joffrin, E and Kasemann, C and Kallenbach, A and Kalvin, S and Kantor, M and Kappatou, A and Kardaun, O and Karhunen, J and Kim, D and Kimmig, S and Kirk, A and Klingshirn, HJ and Kocan, M and Koch, F and Kocsis, G and Kohn, A and Koppen, M and Kotterl, J and Koslowski, R and Koubiti, M and Kraus, M and Krieger, K and Krivska, A and Kogut, D and Kramer-Flecken, A and Kurki-Suonio, T and Kurzan, B and Lackner, K and Laggner, F and Lang, PT and Lauber, P and Lazanyi, N and Lazaros, A and Lebschy, A and Leuterer, F and Liang, Y and Linsmeier, C and Lipschultz, B and Litnovski, A and Lohs, A and Luhmann, NC and Lunt, T and Lyssoivan, A and Madsen, J and Maier, H and Maj, O and Mailloux, J and Maljaars, E and Mancini, A and Manhard, A and Mank, K and Manso, ME and Mantica, P and Mantsinen, M and Manz, P and Maraschek, M and Markina, E and Martens, C and Martin, P and Mayer, A and Mayer, M and Mazon, D and McCarthy, PJ and McDermott, R and Meisl, G and Meister, H and Medvedeva, A and Merkel, P and Merkel, R and Mertens, V and Meyer, H and Meyer, O and Milanesio, D and Miettunen, J and Mlynek, A and Monaco, F and Moro, A and Moseev, D and Muller, HW and Muller, S and Munich, M and Nabais, F and Nemes-Czopf, A and Neu, G and Neu, R and Nielsen, AH and Nikolaeva, V and Nielsen, SK and Nocente, M and Nold, B and Noterdaeme, JM and Nowak, S and Oberkofler, M and Ochoukov, R and Odstrcil, T and Papp, G and Park, HK and Pau, A and Pautasso, G and Penzel, F and Petersson, P and Piovesan, P and Piron, C and Plaum, B and Plockl, B and Plyusnin, V and Podoba, Y and Pokol, G and Pompon, F and Poli, E and Polozhiy, K and Porte, L and Potzel, S and Preuss, R and Prisiazhniuk, D and Utterich, TP and Ramish, M and Rapson, C and Rasmussen, J and Rathgeber, SK and Raupp, G and Refy, D and Reich, M and Reimold, F and Reinke, M and Ribeiro, T and Riedl, R and Rittich, D and Rocchi, G and Rodriguez-Ramos, M and Rohde, V and Roth, J and Rott, M and Rubel, M and Ryter, F and Saarelma, S and Salewski, M and Salmi, A and Sanchis-Sanchez, L and Santos, G and Santos, J and Sauter, O and Scarabosio, A and Schall, G and Schmid, K and Schmitz, O and Schneider, PA and Schneider, W and Schneller, M and Schrittwieser, R and Schubert, M and Schwarz-Selinger, T and Schweinzer, J and Scott, B and Sehmer, T and Sertoli, M and Shalpegin, A and Sias, G and Siccinio, M and Sieglin, B and Sigalov, A and Silva, A and Silva, C and Simon, P and Simpson, J and Snicker, A and Sommer, F and Sozzi, C and Spolaore, M and Stejner, M and Stober, J and Stobbe, F and Stroth, U and Strumberger, E and Sugiyama, K and Sun, HJ and Suttrop, W and Szepesi, T and Tal, B and Tala, T and Tardini, G and Tichmann, C and Told, D and Tophoj, L and Tudisco, O and von Toussaint, U and Trevisan, G and Treutterer, W and Tripsky, M and Valisa, M and Valovic, M and Varela, P and Varoutis, S and Vezinet, D and Vianello, N and Vicente, J and Vierle, T and Viezzer, E and Vorpahl, C and Wagner, D and Wang, X and Wauters, T and Weidl, I and Weiland, M and Weller, A and Wenninger, R and Wieland, B and Wiesinger, M and Willensdorfer, M and Wiringer, B and Wischmeier, M and Wolf, R and Wolfrum, E and Wunderlich, D and Wursching, E and Yang, Z and Yu, Q and Zammuto, I and Zarzoso, D and Zasche, D and van Zeeland, M and Zehetbauer, T and Zilker, M and Zoletnik, S},
  issn         = {0029-5515},
  journal      = {NUCLEAR FUSION},
  keyword      = {tokamak physics,nuclear fusion,ITER,DEMO},
  language     = {eng},
  location     = {Govt Russian Federat, St Petersburg, RUSSIA},
  number       = {10},
  pages        = {12},
  publisher    = {IOP PUBLISHING LTD},
  title        = {Recent ASDEX upgrade research in support of ITER and DEMO},
  url          = {http://dx.doi.org/10.1088/0029-5515/55/10/104010},
  volume       = {55},
  year         = {2015},
}

Chicago
Zohm, H, J Ahn, L Aho-Mantila, S Auml;kaslompolo, C Angioni, O Asunta, M de Baar, et al. 2015. “Recent ASDEX Upgrade Research in Support of ITER and DEMO.” Nuclear Fusion 55 (10).
APA
Zohm, H., Ahn, J., Aho-Mantila, L., Auml;kaslompolo, S., Angioni, C., Asunta, O., de Baar, M., et al. (2015). Recent ASDEX upgrade research in support of ITER and DEMO. NUCLEAR FUSION, 55(10). Presented at the 25th Fusion Energy Conference (FEC).
Vancouver
1.
Zohm H, Ahn J, Aho-Mantila L, Auml;kaslompolo S, Angioni C, Asunta O, et al. Recent ASDEX upgrade research in support of ITER and DEMO. NUCLEAR FUSION. BRISTOL: IOP PUBLISHING LTD; 2015;55(10).
MLA
Zohm, H, J Ahn, L Aho-Mantila, et al. “Recent ASDEX Upgrade Research in Support of ITER and DEMO.” NUCLEAR FUSION 55.10 (2015): n. pag. Print.