Projections of H-mode access and edge pedestal in the SPARC tokamak

Hughes, J.W.; Howard, Nathan; Rodriguez-Fernandez, P.; Creely, A. J.; Kuang, Adam; Snyder, P. B.; Wilks, Theresa; Sweeney, R.; Greenwald, M.

doi:10.1017/s0022377820001300

Cited by 24 publications

(40 citation statements)

References 85 publications

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“…Both of these phenomena, as well as others, including the ability to maintain high-quality H-mode confinement and the implications of reduced pedestal quality, are considered in greater detail in Hughes et al. (2020). It is shown in Hughes et al.…”

Section: Investigation Of Sparc Physicsmentioning

confidence: 99%

Overview of the SPARC tokamak

et al. 2020

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The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ( $B_0 = 12.2$ T), compact ( $R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ( $H_{98,y2} = 0.7$ ) and, with the nominal assumption of $H_{98,y2} = 1$ , SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ( $\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$ ), high temperature ( $\langle T_e \rangle \approx 7$ keV) and high power density ( $P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$ ) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.

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Section: Investigation Of Sparc Physicsmentioning

confidence: 99%

Overview of the SPARC tokamak

et al. 2020

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“…As shown in figure 6( a ), the EPED model indicates that the pedestal is limited by peeling modes and the strong shaping suggests a wide range of operation with a favourable density scaling, given that the ballooning boundary is far from nominal parameters (in part due to the low Greenwald fraction, ). Further examination of SPARC pedestal predictions and confinement mode transitions is presented in Hughes et al (2020). As discussed earlier, pedestal density is treated in this work as an input, and it is assumed to be achievable in H-mode operation.…”

Section: Integrated Modelling Of Sparc Plasmasmentioning

confidence: 99%

Predictions of core plasma performance for the SPARC tokamak

et al. 2020

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SPARC is designed to be a high-field, medium-size tokamak aimed at achieving net energy gain with ion cyclotron range-of-frequencies (ICRF) as its primary auxiliary heating mechanism. Empirical predictions with conservative physics indicate that SPARC baseline plasmas would reach $Q\approx 11$ , which is well above its mission objective of $Q>2$ . To build confidence that SPARC will be successful, physics-based integrated modelling has also been performed. The TRANSP code coupled with the theory-based trapped gyro-Landau fluid (TGLF) turbulence model and EPED predictions for pedestal stability find that $Q\approx 9$ is attainable in standard H-mode operation and confirms $Q > 2$ operation is feasible even with adverse assumptions. In this analysis, ion cyclotron waves are simulated with the full wave TORIC code and alpha heating is modelled with the Monte–Carlo fast ion NUBEAM module. Detailed analysis of expected turbulence regimes with linear and nonlinear CGYRO simulations is also presented, demonstrating that profile predictions with the TGLF reduced model are in reasonable agreement.

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“…Empirical scalings (Eich et al 2013;Brunner et al 2018b;Eich et al 2020) for the scrape-off layer (SOL) heat flux width, indicate that unprecedented high unmitigated peak parallel heat fluxes (q > 10 GW m −2 ) are anticipated in the SPARC divertor. Furthermore, transient events such as edge-localized modes (ELMs) and disruptions impose heat flux and structural loading conditions comparable with ITER and will pose a significant challenge for SPARC (Hughes et al 2020;Sweeney et al 2020). At the same time, it is important to note that these predictions for SPARC rely on extrapolations from the experimental databases.…”

Section: Introductionmentioning

confidence: 99%

Divertor heat flux challenge and mitigation in SPARC

et al. 2020

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Owing to its high magnetic field, high power, and compact size, the SPARC experiment will operate with divertor conditions at or above those expected in reactor-class tokamaks. Power exhaust at this scale remains one of the key challenges for practical fusion energy. Based on empirical scalings, the peak unmitigated divertor parallel heat flux is projected to be greater than 10 GW m−2. This is nearly an order of magnitude higher than has been demonstrated to date. Furthermore, the divertor parallel Edge-Localized Mode (ELM) energy fluence projections (~11–34 MJ m−2) are comparable with those for ITER. However, the relatively short pulse length (~25 s pulse, with a ~10 s flat top) provides the opportunity to consider mitigation schemes unsuited to long-pulse devices including ITER and reactors. The baseline scenario for SPARC employs a ~1 Hz strike point sweep to spread the heat flux over a large divertor target surface area to keep tile surface temperatures within tolerable levels without the use of active divertor cooling systems. In addition, SPARC operation presents a unique opportunity to study divertor heat exhaust mitigation at reactor-level plasma densities and power fluxes. Not only will SPARC test the limits of current experimental scalings and serve for benchmarking theoretical models in reactor regimes, it is also being designed to enable the assessment of long-legged and X-point target advanced divertor magnetic configurations. Experimental results from SPARC will be crucial to reducing risk for a fusion pilot plant divertor design.

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Projections of H-mode access and edge pedestal in the SPARC tokamak

Cited by 24 publications

References 85 publications

Overview of the SPARC tokamak

Overview of the SPARC tokamak

Predictions of core plasma performance for the SPARC tokamak

Divertor heat flux challenge and mitigation in SPARC

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