Model predictive control of KSTAR equilibrium parameters enabled by TRANSP

Boyer, Mark D.; Yuan, Xiaolin; Ahn, Jeongmin; Hahn, S.H.; Nazikian, R.; Poli, F. M.; Sabbagh, S. A.

doi:10.1088/1741-4326/ab9c4a

Cited by 5 publications

(5 citation statements)

References 43 publications

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“…The dashed line shown is an upper limit of κ = 3.4-l i derived from the experience of NSTX for the design of future spherical tokamaks [30]. A boundary, such as this has been proposed for a model predictive control scheme for tokamaks [31]. This indicates that MAST-U still potentially has some margin to increase the elongation of its plasmas, especially as l i is lowered even further in future campaigns.…”

Section: Vertical Stabilitymentioning

confidence: 99%

Operational space and performance limiting events in the first physics campaign of MAST-U

Berkery

Sabbagh

Kogan

et al. 2023

Plasma Phys. Control. Fusion

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The MAST-U fusion plasma research device, the upgrade to the Mega Amp Spherical Tokamak, has recently completed its first campaign of physics operation. MAST-U operated with Ohmic, or one or two neutral beams for heating, at 400-800 kA plasma current, in conventional or “SuperX” divertor configurations. Equilibrium reconstructions provide key plasma physics parameters vs. time for each discharge, and diagrams are produced which show where the prevalence of operation occurred as well as the limits in various operational spaces. When compared to stability limits, the operation of MAST-U so far has generally stayed out of the low q, low density instability region, and below the high density Greenwald limit, high beta global stability limits, and high elongation vertical stability limit. MAST-U still has the potential to reach higher elongation, which could benefit the plasma performance. Despite the majority of operation happening below established stability limits, disruptions did occur in the flat-top phase of MAST-U plasmas. The reasons for these disruptions are highlighted, and possible strategies to avoid them and to extend the operational space of MAST-U in future campaigns are discussed.

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Section: Vertical Stabilitymentioning

confidence: 99%

Operational space and performance limiting events in the first physics campaign of MAST-U

Berkery

Sabbagh

Kogan

et al. 2023

Plasma Phys. Control. Fusion

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“…The pressure and safety factor evolution by the RAPTOR transport code [78], with a simple transport model, has been coupled to the free-boundary equilibrium code LIUQE [79] to compute KERs that are used by the PCS system of the TCV tokamak [80]. A similar project to include the KSTAR PCS coupled to the TRANSP code [81,82] simulation of the plasma and MHD equilibrium is underway [83]. At present only highly reduced models of the plasma fit to predictive TRANSP simulations are used in the control coupling.…”

Section: Integration Of Plasma Control Systemmentioning

confidence: 99%

Advances in prediction of tokamak experiments with theory-based models

et al. 2022

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The successful validation of theory-based models of transport, magnetohydrodynamic stability, heating and current drive, with tokamak measurements over the last 20 years, has laid the foundation for a new era where these models can be routinely used in a ‘predict first’ approach to design and predict the outcomes of experiments on tokamaks today. The capability to predict the plasma confinement and core profiles with a quantified uncertainty, based on a multi-machine, international, database of experience, will provide confidence that a proposed discharge will remain within the operational limits of the tokamak. Developing this predictive capability for the first generation of burning plasma devices, beginning with ITER, and progressing to tokamak demonstration reactors, is a critical mission of fusion energy research. Major advances have been made implementing this predict first methodology on today’s tokamaks. An overview of several of these recent advances will be presented, providing the integrated modeling foundations of the experimental successes. The first steps to include boundary plasmas, and tokamak control systems, have been made. A commitment to predicting experiments as part of the planning process is needed in order to collect predictive accuracy data and evolve the models and software into a robust whole discharge pulse design simulator.

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“…The model-based control algorithm enables multi-input multioutput control over the diverter coils to track operator specified snowflake diverter characteristics. In addition to shape control, a reduced-model-based feedback control of the safety factor profile was developed [149] and tested using the recently improved TRANSP closed-loop control modelling [150]. To enable fast profile measurements suitable for real-time applications, a scalable framework for Thomson scattering analysis was established using high speed analog-to-digital converters, a dedicated real-time server, and new analysis software optimized for fast and accurate fitting of the Thomson spectra [151,152].…”

Section: Scenario Optimization and Controlmentioning

confidence: 99%

NSTX-U theory, modeling and analysis results

Guttenfelder¹,

Battaglia²,

Белова³

et al. 2022

Nucl. Fusion

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The mission of the low aspect ratio spherical tokamak NSTX-U is to advance the physics basis and technical solutions required for optimizing the configuration of next-step steady-state tokamak fusion devices. NSTX-U will ultimately operate at up to 2 MA of plasma current and 1 T toroidal field on axis for 5 seconds, and has available up to 15 MW of Neutral Beam Injection (NBI) power at different tangency radii and 6 MW of High Harmonic Fast Wave (HHFW) heating. With these capabilities NSTX-U will develop the physics understanding and control tools to ramp-up and sustain high performance fully non-inductive plasmas with large bootstrap fraction and enhanced confinement enabled via the low aspect ratio, high beta configuration. With its unique capabilities, NSTX-U research also supports ITER and other critical fusion development needs. Super-Alfvénic ions in beam-heated NSTX-U plasmas access energetic particle parameter space that is relevant for both -heated conventional and low aspect ratio burning plasmas. NSTX-U can also generate very large target heat fluxes to test conventional and innovative plasma exhaust and plasma facing component (PFC) solutions. This paper summarizes recent analysis, theory and modelling progress to advance the tokamak physics basis in the areas of macrostability and 3D fields, energetic particle stability and fast ion transport, thermal transport and pedestal structure, boundary and plasma material interaction, RF heating, scenario optimization and real-time control.

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Model predictive control of KSTAR equilibrium parameters enabled by TRANSP

Cited by 5 publications

References 43 publications

Operational space and performance limiting events in the first physics campaign of MAST-U

Operational space and performance limiting events in the first physics campaign of MAST-U

Advances in prediction of tokamak experiments with theory-based models

NSTX-U theory, modeling and analysis results

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