TY - JOUR
T1 - Overview of physics studies on ASDEX Upgrade
JF - Nuclear Fusion
Y1 - 2019
A1 - Meyer, H.
A1 - Angioni, C.
A1 - C.G. Albert
A1 - N. Arden
A1 - R. Arredondo Parra
A1 - Asunta, O.
A1 - de Baar, M.
A1 - Balden, M.
A1 - V. Bandaru
A1 - Behler, K.
A1 - Bergmann, A.
A1 - Bernardo, J.
A1 - Bernert, M.
A1 - A. Biancalani
A1 - Bilato, R.
A1 - Birkenmeier, G.
A1 - Blanken, T. C.
A1 - Bobkov, V.
A1 - Bock, A.
A1 - Bolzonella, T.
A1 - A. Bortolon
A1 - B. Böswirth
A1 - Bottereau, C.
A1 - Bottino, A.
A1 - van den Brand, H.
A1 - Brezinsek, S.
A1 - Brida, D.
A1 - Brochard, F.
A1 - C. Bruhn
A1 - Buchanan, J.
A1 - Buhler, A.
A1 - Burckhart, A.
A1 - Camenen, Y.
A1 - D. Carlton
A1 - Carr, M.
A1 - Carralero, D.
A1 - C. Castaldo
A1 - Cavedon, M.
A1 - C. Cazzaniga
A1 - S. Ceccuzzi
A1 - Challis, C.
A1 - Chankin, A.
A1 - Chapman, S.
A1 - C. Cianfarani
A1 - Clairet, F.
A1 - Coda, S.
A1 - Coelho, R.
A1 - Coenen, J. W.
A1 - Colas, L.
A1 - Conway, G. D.
A1 - Costea, S.
A1 - Coster, D. P.
A1 - Cote, T. B.
A1 - Creely, A.
A1 - G. Croci
A1 - Cseh, G.
A1 - Czarnecka, A.
A1 - I. Cziegler
A1 - den Harder, N.
A1 - Jaulmes, F.
A1 - Kantor, M.
A1 - Karhunen, J.
A1 - Miettunen, J.
A1 - Vanovac, B.
A1 - EUROfusion MST1 Team
A1 - et al.
AB - The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q 95 = 5.5, ) at low density. Higher installed electron cyclotron resonance heating power 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m−1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of ‘natural’ no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle—measured for the first time—or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.
PB - IOP Publishing
VL - 59
IS - 11
U1 - FP
U2 - TP
U5 - 87a8b0ff65b4dc41f80072ac74a6868a
ER -
TY - JOUR
T1 - Field-Line Localized Destabilization of Ballooning Modes in Three-Dimensional Tokamaks
JF - Physical Review Letters
Y1 - 2017
A1 - Willensdorfer, M.
A1 - Cote, T. B.
A1 - Hegna, C.
A1 - Suttrop, W.
A1 - Zohm, H.
A1 - Dunne, M.
A1 - Strumberger, E.
A1 - Birkenmeier, G.
A1 - Denk, S. S.
A1 - Vanovac, B.
A1 - Mink, F.
A1 - Luhmann, N. C.
A1 - ASDEX Upgrade Team
AB - Field-line localized ballooning modes have been observed at the edge of high confinement mode plasmas in ASDEX Upgrade with rotating 3D perturbations induced by an externally applied n = 2 error field and during a moderate level of edge localized mode mitigation. The observed ballooning modes are localized to the field lines which experience one of the two zero crossings of the radial flux surface displacement during one rotation period. The localization of the ballooning modes agrees very well with the localization of the largest growth rates from infinite-n ideal ballooning stability calculations using a realistic 3D ideal magnetohydrodynamic equilibrium. This analysis predicts a lower stability with respect to the axisymmetric case. The primary mechanism for the local lower stability is the 3D distortion of the local magnetic shear
PB - American Physical Society
VL - 119
IS - 8
U1 - FP
U2 - PEPD
U5 - 1d6ed9bafa05f7cdb28d82d1f88a7a70
ER -