A Fusion Nuclear Science Facility for a fast-track path to DEMO

Garofalo, A. M.; Abdou, Mohamed; Canik, J.; Chan, V. S.; Hyatt, A.W.; Hill, D. N.; Morley, Neil B.; Navratil, G.A.; Sawan, M.E.; Taylor, T. S.; Wong, C.P.C.; Wu, Wen; Ying, Alice

doi:10.1016/j.fusengdes.2014.03.055

Cited by 49 publications

(47 citation statements)

References 15 publications

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“…The idea of FNSF was first proposed in the US in the 1980s [4,11] and was further studied and evolved in an IEA international study [3]. More detailed considerations of the design of FNSF were evaluated in [153][154][155][156]. All these studies developed and evolved a specific vision for FNSF which we will discuss first followed by brief description of a modified vision of FNSF recently advocated by some researchers.…”

Section: Fnsf Mission and Major Design Features And Parametersmentioning

confidence: 99%

“…The two options considered for tokamak are the standard aspect ratio (A typically about 3) tokamak [153][154][155] and the very small aspect ratio (A ∼ 1.3) tokamak normally called Spherical Torus (ST) [156]. For a tokamak (standard A & ST) this leads to recommendation of:…”

Section: Fnsf Mission and Major Design Features And Parametersmentioning

confidence: 99%

“…A detailed cost estimate of FNSF has not yet been made. However, very rough estimate of the cost based on the studies in [153,154,155] is in the range of 3-4 billion dollars for standard aspect ratio tokamak. This is plausible since the size of FNSF considered in these studies is less than 20% of ITER and expensive superconducting magnets are not used.…”

Section: Fnsf Mission and Major Design Features And Parametersmentioning

confidence: 99%

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Blanket/first wall challenges and required R&D on the pathway to DEMO

Abdou

Morley

Smolentsev

et al. 2015

Fusion Engineering and Design

276

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a b s t r a c tThe breeding blanket with integrated first wall (FW) is the key nuclear component for power extraction, tritium fuel sustainability, and radiation shielding in fusion reactors. The ITER device will address plasma burn physics and plasma support technology, but it does not have a breeding blanket. Current activities to develop "roadmaps" for realizing fusion power recognize the blanket/FW as one of the principal remaining challenges. Therefore, a central element of the current planning activities is focused on the question: what are the research and major facilities required to develop the blanket/FW to a level which enables the design, construction and successful operation of a fusion DEMO? The principal challenges in the development of the blanket/FW are: (1) the Fusion Nuclear Environment -a multiple-field environment (neutrons, heat/particle fluxes, magnetic field, etc.) with high magnitudes and steep gradients and transients; (2) Nuclear Heating in a large volume with sharp gradients -the nuclear heating drives most blanket phenomena, but accurate simulation of this nuclear heating can be done only in a DT-plasma based facility; and (3) Complex Configuration with blanket/first wall/divertor inside the vacuum vessel -the consequence is low fault tolerance and long repair/replacement time.These blanket/FW development challenges result in critical consequences: (a) non-fusion facilities (laboratory experiments) need to be substantial to simulate multiple fields/multiple effects and must be accompanied by extensive modeling; (b) results from non-fusion facilities will be limited and will not fully resolve key technical issues. A DT-plasma based fusion nuclear science facility (FNSF) is required to perform "multiple effects" and "integrated" experiments in the fusion nuclear environment; and (c) the Reliability/Availability/Maintainability/Inspectability (RAMI) of fusion nuclear components is a major challenge and is one of the primary reasons why the blanket/FW will pace fusion development toward a DEMO.This paper summarizes the top technical issues and elucidates the primary challenges in developing the blanket/first wall and identifies the key R&D needs in non-fusion and fusion facilities on the path to DEMO.Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

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Section: Fnsf Mission and Major Design Features And Parametersmentioning

confidence: 99%

Section: Fnsf Mission and Major Design Features And Parametersmentioning

confidence: 99%

Section: Fnsf Mission and Major Design Features And Parametersmentioning

confidence: 99%

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Blanket/first wall challenges and required R&D on the pathway to DEMO

Abdou

Morley

Smolentsev

et al. 2015

Fusion Engineering and Design

276

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“…A study of various disruption types on JT-60U, including those caused by tearing modes, has been reported [19]. A brief study of disruptivity as a function of the safety factor and the normalized plasma beta on DIII-D has been reported [20].…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of m/n = 2/1 locked and quasi-stationary modes with rotating precursors at DIII-D

Sweeney¹,

Choi²,

Haye³

et al. 2016

Nucl. Fusion

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Abstract.A database has been developed to study the evolution, the nonlinear effects on equilibria, and the disruptivity of locked and quasi-stationary modes with poloidal and toroidal mode numbers m = 2 and n = 1 at DIII-D. The analysis of 22,500 discharges shows that more than 18% of disruptions are due to locked or quasistationary modes with rotating precursors (not including born locked modes). A parameter formulated by the plasma internal inductance l i divided by the safety factor at 95% of the poloidal flux, q 95 , is found to exhibit predictive capability over whether a locked mode will cause a disruption or not, and does so up to hundreds of milliseconds before the disruption. Within 20 ms of the disruption, the shortest distance between the island separatrix and the unperturbed last closed flux surface, referred to as d edge , performs comparably to l i /q 95 in its ability to discriminate disruptive locked modes. Out of all parameters considered, d edge also correlates best with the duration of the locked mode. Disruptivity following a m/n = 2/1 locked mode as a function of the normalized beta, β N , is observed to peak at an intermediate value, and decrease for high values. The decrease is attributed to the correlation between β N and q 95 in the DIII-D operational space. Within 50 ms of a locked mode disruption, average behavior includes exponential growth of the n = 1 perturbed field, which might be due to the 2/1 locked mode. Surprisingly, even assuming the aforementioned 2/1 growth, disruptivity following a locked mode shows little dependence on island width up to 20 ms before the disruption. Separately, greater deceleration of the rotating precursor is observed when the wall torque is large. At locking, modes are often observed to align at a particular phase, which is likely related to a residual error field. Timescales associated with the mode evolution are also studied and dictate the response times necessary for disruption avoidance and mitigation. Observations of the evolution of β N during a locked mode, the effects of poloidal beta on the saturated width, and the reduction in Shafranov shift during locking are also presented.

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“…For a fusion suclear science facility (FNSF) based on an advanced tokamak (AT), the divertor must not only promote detachment at low upstream density but also effectively confine recycled neutral particles such that the main plasma density level remains significantly lower than allowed in standard tokamak operation. The small‐angle slot (SAS) divertor, under development at DIII‐D,– is designed to provide a solution suitable for an AT‐based FNSF.…”

Section: Introductionmentioning

confidence: 99%

Drift effects and up–down asymmetry in balanced double‐null DIII‐D divertor configurations

Meier

Covele

Guo

et al. 2018

Contributions to Plasma Physics

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In a preliminary design study for a small‐angle slot (SAS) divertor configuration suitable for DIII‐D double‐null advanced tokamak (AT) plasmas, a conceptual “SAS 2” slot divertor configuration has been modelled with SOLPS‐ITER. A balanced double‐null equilibrium, representing an H‐mode AT plasma, is employed, with 5 MW neutral beam input power. In simulations with fully recycling walls and no pumping, an up–down‐symmetric open divertor geometry is compared with the SAS 2 configuration. In density scans without electric or magnetic drifts, the upstream separatrix electron density needed to achieve detachment at both target strike points (ne, sep, det.) is ∼35% lower in SAS 2 than in the open configuration, with ne, sep, det. = 1.66 and 2.59 × 1019 m−3, respectively. With drifts, the same ∼35% difference remains, but detachment density for each configuration is shifted up by ∼15%, giving ne, sep, det. = 1.94 and 2.99 × 1019 m−3, respectively. Cryopumping is modelled for the SAS 2 divertor, and with a pump duct deep in the upper slot on the common‐flux side, detachment density is shifted up by ∼15–20%. Strong pumping in the upper slot delays detachment there compared with the lower slot, regardless of drift direction. This research sets the stage for future modelling that would explore more sophisticated cryopumping configurations, and sensitivity of divertor performance to changes in magnetic balance and input power.

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A Fusion Nuclear Science Facility for a fast-track path to DEMO

Cited by 49 publications

References 15 publications

Blanket/first wall challenges and required R&D on the pathway to DEMO

Blanket/first wall challenges and required R&D on the pathway to DEMO

Statistical analysis of m/n = 2/1 locked and quasi-stationary modes with rotating precursors at DIII-D

Drift effects and up–down asymmetry in balanced double‐null DIII‐D divertor configurations

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