Doughnuts and the Fourth Dimension

McCarthy, Alan

doi:10.33178/boolean.2014.15

Cited by 3 publications

(3 citation statements)

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“…Diagnostic signals are processed by several advanced data processing algorithms implemented in the control system. Plasma position, shape, and β are computed in real-time using function parametrization [24,25]. This method relies on the statistical analysis of a large database of simulated equilibria to obtain a functional representation (typically quadratic polynomials) of the above mentioned physical parameters in terms of the values of the magnetic probe and flux loop measurements.…”

Section: Data Evaluation Algorithmsmentioning

confidence: 99%

Overview of advances in ASDEX Upgrade plasma control to support critical physics research for ITER and beyond

Kudlacek,

David,

Gomez

et al. 2024

Nucl. Fusion

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The successful operation of fusion reactors requires operatingscenarios with good core confinement and acceptable first wall heat loads, thatare stable and robust to external perturbations. This poses both physical andtechnological challenges. One of the technologies addressing these challengesis a complex feedback control system. They support advances in physicalunderstanding and help to ensure stable operating conditions. Operatingmarginally stable plasmas often leads to off-normal events (such as disruptions)and feedback control can prevent these to some extent.This contribution gives an overview of the main results of the developmentand operation of the feedback control algorithms on ASDEX Upgrade (AUG).Fueling actuators, using a combination of gas valves and pellet injection, cansimultaneously control neutral density of the divertor and the density of theplasma core above the Greenwald limit. Impurity injection is employed to controlthe position of the X-point radiator, allowing the creation of an ELM-suppressedH-mode with high radiation fraction. Heating actuators are used to controlthe plasma energy content, which supports advanced tokamak experiments andenables stable I-mode operation, and the electron temperature control, whichsupports turbulence studies. In control technology, AUG has pioneered the useof virtual actuators, which allow effective use of the limited number of heatingactuators, adaptive control policies, and exception handling. Such technologieswill also be used in ITER. Advanced nonlinear state observers (RAPTOR,RAPDENS) and codes to evaluate the power deposition properties (RABBIT,TORBEAM) are available for routine use in the AUG feedback controllers.Extensive use of the AUG Discharge Control System (DCS) further enhancesthe research capabilities of this machine.

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Section: Data Evaluation Algorithmsmentioning

confidence: 99%

Overview of advances in ASDEX Upgrade plasma control to support critical physics research for ITER and beyond

Kudlacek,

David,

Gomez

et al. 2024

Nucl. Fusion

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“…We have selected the AUG discharge #30411 at 5.4 s as the baseline case for our simulations. A realistic magnetic equilibrium reconstruction was performed using the CLISTE code [22]. In the simulation we also include the radial electric field derived from a typical plasma potential profile at AUG, shown in figure 3 (in black).…”

Section: Proposed Experimental Setupmentioning

confidence: 99%

Conceptual design of a scintillator based Imaging Heavy Ion Beam Probe for the ASDEX Upgrade tokamak

et al. 2017

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A conceptual design of a new diagnostic for the simultaneous space and time resolved measurement of plasma density, potential and poloidal magnetic field fluctuations at ASDEX Upgrade is proposed. The diagnostic combines the detection techniques of standard heavy ion beam probes (HIBP) and scintillator based fast ion loss detectors (FILD), making use of an atomic beam to probe plasma parameters with high spatio-temporal resolution. This new approach takes advantage of using a neutral probe beam and a scintillator plate as detection system. The combination of these two techniques makes the diagnostic more compact than standard HIBP facilitating its integration in the machine. Simulations using an orbit following code have been carried out to investigate the viability of the proposed detection method based on the displacement of the beam strike-line on the scintillator plate. Relative plasma potential fluctuations from 10% to 100% in the potential well induce localized displacements in the strike line in the range of 0.1-1.0 mm, while poloidal magnetic field fluctuations such as those arising from edge currents produce displacements in the order of mm. The use of a scintillator screen provides virtually infinite spatial resolution together with a temporal resolution up to the MHz range, needed for the identification of internal fluctuations.

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“…Plasma position and shape control on ASDEX Upgrade is performed using function parameterization [1,2]. This method relies on the statistical analysis of a large database of simulated experiments to obtain a functional representation of the intrinsic physical parameters of the plasma position and shape in terms of the values of the magnetic probe and flux loop measurements.…”

Section: Introductionmentioning

confidence: 99%

Magnetics only real-time equilibrium reconstruction on ASDEX Upgrade

Giannone,

Weiland,

Fischer

et al. 2024

Plasma Phys. Control. Fusion

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Real-time reconstruction of the magnetic equilibrium provides fundamental control of plasma shape and position in a tokamak. Details of the implementation of the equilibrium reconstruction code developed for the ASDEX Upgrade tokamak (JANET++) are summarised. Cubic Hermite splines are introduced as current density basis functions for solving the Grad-Shafranov equation. The choice of the optimal Tikhonov regularisation parameter is discussed. The code is validated by comparing the results of the equilibrium reconstruction with those of further equilibrium recon- structions available on ASDEX Upgrade (CLISTE and IDE). In a high time resolution study of a discharge with edge localised modes (ELM), the poloidal asymmetry of the fits and magnetic probe measurements suggest that the real-time equilibrium re- construction captures the essential features of the current density redistribution in an ELMing edge plasma. An efficient algorithm to locate multiple X-points and identify the active one in advanced X-divertor and snowflake divertor configurations is presented.

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Doughnuts and the Fourth Dimension

Cited by 3 publications

References 0 publications

Overview of advances in ASDEX Upgrade plasma control to support critical physics research for ITER and beyond

Overview of advances in ASDEX Upgrade plasma control to support critical physics research for ITER and beyond

Conceptual design of a scintillator based Imaging Heavy Ion Beam Probe for the ASDEX Upgrade tokamak

Magnetics only real-time equilibrium reconstruction on ASDEX Upgrade

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