Measurements and modelling of diamagnetic flux in ASDEX Upgrade

Giannone, L.; Fischer, R.; Kappatou, A.; Tardini, G.; Weiland, M.; Angioni, C.; Fable, E.; Griener, M.; McDermott, R. M.; Sieglin, B.; Vuuren, A. Jansen van; Bilato, R.; Dunne, M.; Gude, A.; Kallenbach, A.; Kurz, Joachim; Maraschek, M.; Rittich, D.; Ryter, F.; Schneider, P. A.; Schuhbeck, K. H.; Stroth, U.; Zohm, H.

doi:10.1088/1741-4326/abea56

Cited by 8 publications

(5 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The diamagnetic energy is calculated as part of the equilibrium reconstruction with EFIT++. W dia is not output by TRANSP by default and is derived from the computed thermal W th and fast ion perpendicular W f⊥ energy components as W dia = W th + 1.5 W f⊥ [63].…”

Section: Consistency Checksmentioning

confidence: 99%

Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Štancar,

Kirov,

Auriemma

et al. 2023

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

In the paper we present an overview of interpretive modelling of a database of JET-ILW 2021 D-T discharges using the TRANSP code. The main aim is to assess our capability of computationally reproducing the fusion performance of various D-T plasma scenarios using different external heating and D-T mixtures, and to understand the performance driving mechanisms. We find that interpretive simulations confirm a general power-law relationship between increasing external heating power and fusion output, which is supported by absolutely calibrated neutron yield measurements. A comparison of measured and computed D-T neutron rates shows that the calculations’ discrepancy depends on the absolute neutron yield. The calculations are found to agree well with measurements for higher performing discharges with external heating power above ∼20 M W , while low-neutron shots display an average discrepancy of around +40% compared to measured neutron yields. A similar trend is found for the ratio between thermal and beam-target fusion, where larger discrepancies are seen in shots with dominant beam-driven performance. We compare the observations to studies of JET-ILW D discharges, to find that on average the fusion performance is well modelled over a range of heating power, although an increased unsystematic deviation for lower-performing shots is observed. The ratio between thermal and beam-induced D-T fusion is found to be increasing weakly with growing external heating power, with a maximum value of ≳ 1 achieved in a baseline scenario experiment. An evaluation of the fusion power computational uncertainty shows a strong dependence on the plasma scenario type and fusion drive characteristics, varying between ±25% and 35%. D-T fusion alpha simulations show that the ratio between volume-integrated electron and ion heating from alphas is ≲ 10 for the majority of analysed discharges. Alphas are computed to contribute between ∼15% and 40% to the total electron heating in the core of highest performing D-T discharges. An alternative workflow to TRANSP was employed to model JET D-T plasmas with the highest fusion yield and dominant non-thermal fusion component because of the use of fundamental radio-frequency heating of a large minority in the scenario, which is calculated to have provided ∼10% to the total fusion power.

show abstract

Section: Consistency Checksmentioning

confidence: 99%

Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Štancar,

Kirov,

Auriemma

et al. 2023

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…The main reason the absorbed NBI power is significantly below the nominal power are FI prompt losses, which are significant when counter-injection beams are used, as is the case here. Hence, while the total heating power is increased by 43% by the addition of NBI (from 7 MW to 10 MW), the plasma energy, as calculated by the integrated data analysis (IDA) for equilibrium reconstruction [32,33] and measured via the diamagnetic loop [34], increases only by about 23% (0.26 MJ to 0.32 MJ). This hints to increased transport (worse confinement) at increasing heating powers, which is usually referred to as power degradation, a common observation in both tokamaks and stellarators [35][36][37][38].…”

Section: Negative Triangulariy Plasmas In Asdex Upgradementioning

confidence: 99%

Overview of initial negative triangularity plasma studies on the ASDEX Upgrade tokamak

et al. 2022

Self Cite

View full text Add to dashboard Cite

An overview of results of negative triangularity (NT) studies from the ASDEX Upgrade tokamak (AUG) is given. Moderate values of the negative triangularity in the range of δaverage ≈ −0.2 have been obtained. Results from both unfavorable and favorable magnetic configuration in terms of high-confinement mode (H-mode) access are presented. In unfavorable configuration, the ion grad B drift points away from the active x-point, which usually results in a factor of 2 higher power thresholds to enter H-mode. In unfavorable configuration, low-confinement mode (L-mode) operation is confirmed at high auxiliary heating input powers > 10 MW at low collisionality. Under these conditions, plasmas with positive triangularity are usually in H-mode. Highest plasma energies have been obtained using a combination of neutral beam injection, electron- and ion cyclotron resonance heating, where values of the plasma beta of βN ≈ 1.7 have been reached in L-mode. While discharges with mixed auxiliary heating power input show moderate confinement on L-mode levels, plasmas heated with electron cyclotron resonance heating show H-mode like confinement. Operation in favorable configuration, however, leads to H-mode with type-I edge localized modes (ELMs). The power required for the L-H transition is comparable to the typical L-H power threshold in positive triangularity cases (< 2.6 MW), and good confinement of typical positive triangularity H-modes is obtained. The ELM frequency is demonstrated to reach 700 Hz. These results show a clear effect of the NT configuration on the ELM behavior in H-modes, and that on AUG, unfavorable configuration is an essential ingredient if H-mode operation is to be avoided in NT plasmas. So far, in all AUG NT plasmas, power degradation is observed. Initial gyrokinetic simulations of the edge plasma unfavorable configuraion reveal the ion-temperature gradient mode as the fastest growing mode with a subdominant trapped-electron-mode.

show abstract

“…The measured neutron emission rate signal (blue) approaches the classical neutron rate (TRANSP) when the TAEs are mitigated and suppressed after t ∼ 5.4 s. Also, the stored energy rises significantly and the difference between W DIA and W MHD increases while the TAEs are stabilized. This discrepancy with the condition of W MHD > W DIA indicates the beam-ion stored energy increases [51] since the beam-injection geometry of KSTAR is mainly parallel.…”

Section: Change In Spectral and Kinetic Profilesmentioning

confidence: 74%

“…Stored energy (W DIA ) is measured by the diamagnetic loop [50] and compared with the calculated energy (W MHD ) from the equilibrium reconstruction. In particular, as the geometry of NBI in KSTAR is mainly parallel, the parallel fast-ion energy produced by the parallel beam injection has a significant contribution to the W MHD when the beam-ion confinement is enhanced [51].…”

Section: Heating Current Drive and Diagnosticsmentioning

confidence: 99%

Suppression of toroidal Alfvén eigenmodes by the electron cyclotron current drive in KSTAR plasmas

et al. 2022

View full text Add to dashboard Cite

Advanced operation scenarios such as high poloidal beta (βP) or high q min are promising concepts to achieve the steady-state high-performance fusion plasmas. However, those scenarios are prone to substantial Alfvénic activity, causing fast-ion transport and losses. Recent experiments with the advanced operation scenario on KSTAR tokamak have shown that the electron cyclotron current drive (ECCD) is able to mitigate and suppress the beam-ion driven toroidal Alfvén eigenmodes (TAEs) for over several tens of global energy confinement time. Co-current directional intermediate off-axis ECCD lowers the central safety factor slightly and tilts the central q-profile shape so that the continuum damping in the core region increases. Besides, the rise of central plasma pressure and increased thermal-ion Landau damping contribute to TAE stabilization. While the TAEs are suppressed, neutron emission rate and total stored energy increase by approximately 45% and 25%, respectively. Fast-ion transport estimated by TRANSP calculations approaches the classical level during the TAE suppression period. Substantial reduction in fast-ion loss and neutron deficit is also observed. Enhancement of fast-ion confinement by suppressing the TAEs leads to an increase of non-inductive current fraction and will benefit the sustainment of the long-pulse high-performance discharges.

show abstract

Measurements and modelling of diamagnetic flux in ASDEX Upgrade

Cited by 8 publications

References 59 publications

Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Overview of initial negative triangularity plasma studies on the ASDEX Upgrade tokamak

Suppression of toroidal Alfvén eigenmodes by the electron cyclotron current drive in KSTAR plasmas

Contact Info

Product

Resources

About