Real-time feedback control of the plasma density profile on ASDEX Upgrade

Mlynek, A.; Reich, M.; Giannone, L.; Treutterer, W.; Behler, K.; Blank, H. J. de; Buhler, A.; Cole, R.; Eixenberger, H.; Fischer, R.; Lohs, A.; Lüddecke, K.; Merkel, R.; Neu, G.; Ryter, F.; Zasche, D.

doi:10.1088/0029-5515/51/4/043002

Cited by 45 publications

(48 citation statements)

References 16 publications

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“…This can be understood in terms of an interplay between Trapped Electron Modes (TEM) and Ion Temperature Gradient driven modes (ITG), which is theoretically described [81] and experimentally observed [82].…”

Section: Profile Tailoring With Wave Heatingmentioning

confidence: 99%

Control of neoclassical tearing modes

Maraschek

2012

Nucl. Fusion

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Abstract. Neoclassically driven tearing modes (NTM) are a major problem for tokamaks operating in a conventional ELMy H-mode scenario. Depending on the mode numbers these pressure driven perturbations cause a mild reduction of the maximum achievable β N = β t /() before the onset of the NTM, or can even lead to disruptions at low edge safety factor, q 95 . A control of this type of modes in high β N plasmas is therefore of vital interest for magnetically confined fusion plasmas. The control consists of two major approaches, namely the control of the excitation of these modes and the removal, or at least mitigation, of these modes, once an excitation could not be avoided. For both routes examples will be given and the applicability of these approaches to ITER will be discussed.

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Section: Profile Tailoring With Wave Heatingmentioning

confidence: 99%

Control of neoclassical tearing modes

Maraschek

2012

Nucl. Fusion

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“…These diagnostics operate from separate systems on a common shared memory from which and in which they read and place their data. Major components are an equilibrium solver [17], density profile from interferometry [18], ray-tracing for all ECRH-beams and a correlation analysis of the 60 new fast ECE channels with the n=2 component (for (3,2)-NTMs) or the n=1, m=2 component of the Mirnov-signals [15]. Figure 1 summarizes the level reached so far: the ECEMirnov correlation allows reliably to localize a (3,2)-NTM.…”

Section: Ntmsmentioning

confidence: 98%

ECRH on ASDEX Upgrade - System Status, Feed-Back Control, Plasma Physics Results -

Stober

Bock

Höhnle

et al. 2012

EPJ Web of Conferences

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Abstract. The ASDEX Upgrade (AUG) ECRH system now delivers a total of 3.9 MW to the plasma at 140 GHz. Three new units are capable of 2-frequency operation and may heat the plasma alternatively with 2.1 MW at 105 GHz. The system is routinely used with X2, O2, and X3 schemes. For B t = 3.2 T also an ITER-like O1-scheme can be run using 105 GHz. The new launchers are capable of fast poloidal movements necessary for real-time control of the location of power deposition. Here real-time control of NTMs is summarized, which requires a fast analysis of massive data streams (ECE and Mirnov correlation) and extensive calculations (equilibria, ray-tracing). These were implemented at AUG using a modular concept of standardized real-time diagnostics. The new realtime capabilities have also been used during O2 heating to keep the first reflection of the non-absorbed beam fraction on the holographic reflector tile which ensures a well defined second pass of the beam through the central plasma. Sensors for the beam position are fast thermocouples at the edge of the reflector tile. The enhanced ECRH power was used for several physics studies related to the unique feature of pure electron heating without fueling and without momentum input. As an example the effect of the variation of the heating mix in moderately heated H-modes is demonstrated using the three available heating systems, i.e. ECRH, ICRH and NBI. Keeping the total input power constant, strong effects are seen on the rotation, but none on the pedestal parameters. Also global quantities as the stored energy are hardly modified. Still it is found that the central ion temperature drops as the ECRH fraction exceeds a certain threshold.

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“…For control and monitoring in DCS raw sensor signals are processed to reconstruct main physics quantities such as plasma separatrix geometry [6], magnetic flux coordinates [7], electron and neutral density and density profiles [8], radiated power, power fluxes, effective heating power components, stored energy, plasma confinement parameters [9,10], MHD and locked mode amplitudes and locations [11,12] and disruption precursors [13,14]. To distribute and parallelise the working load, part of these quantities are not computed by DCS but directly by real-time enabled digital diagnostic systems [15].…”

Section: Measurements and Plasma Reconstructionmentioning

confidence: 99%

ASDEX Upgrade Discharge Control System—A real-time plasma control framework

Treutterer

Cole²,

Lüddecke³

et al. 2014

Fusion Engineering and Design

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ASDEX Upgrade is a fusion experiment with a size and complexity to allow extrapolation of technical and physical conditions and requirements to devices like ITER and even beyond. In addressing advanced physics topics it makes extensive use of sophisticated real-time control methods. It comprises real-time diagnostic integration, dynamically adaptable multivariable feedback schemes, actuator management including load distribution schemes and a powerful monitoring and pulse supervision concept based on segment scheduling and exception handling. The Discharge Control System (DCS) supplies all this functionality on base of a modular software framework architecture designed for real-time operation. It provides system-wide services like workflow management, logging and archiving, self-monitoring and inter-process communication on Linux, VxWorks and Solaris operating systems. By default DCS supports distributed computing, and a communication layer allows multi-directional signal transfer and data-driven process synchronisation over shared memory as well as over a number of real-time networks. The entire system is built following the same common design concept combining a rich set of re-usable generic but highly customisable components with a configurationdriven component deployment method.We will give an overview on the architectural concepts as well as on the outstanding capabilities of DCS in the domains of inter-process communication, generic feedback control and pulse supervision. In each of these domains, DCS has contributed important ideas and methods to the on-going design of the ITER plasma control system. We will identify and describe these essential features and illustrate them with examples from ASDEX Upgrade operation.

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Real-time feedback control of the plasma density profile on ASDEX Upgrade

Cited by 45 publications

References 16 publications

Control of neoclassical tearing modes

Control of neoclassical tearing modes

ECRH on ASDEX Upgrade - System Status, Feed-Back Control, Plasma Physics Results -

ASDEX Upgrade Discharge Control System—A real-time plasma control framework

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