A Description of the Full Particle Orbit Following SPIRAL Code for Simulating Fast-ion Experiments in Tokamaks

Kramer, G. J.; Budny, R. V.; A., Bortolon,; Fredrickson, E.; Fu, G. Y.; Heidbrink, W.W.; R., Nazikian,; Valeo, E.; Zeeland, M. A. Van

doi:10.2172/1056825

Cited by 4 publications

(8 citation statements)

References 7 publications

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“…2012) and SPIRAL (Kramer et al. 2013 a )) to compute the orbits of energetic ions in the presence of rippled 3-D magnetic fields. These codes effectively advance an ion's position with and its change in velocity vector with by computing the Lorentz force () experienced by the ion in the local magnetic field as it moves through the plasma.…”

Section: Numerical Simulation Toolsmentioning

confidence: 99%

“…2013, 2014), the interaction of magnetic perturbations, toroidal Alfvén eigenmodes (TAEs), global Alfvén eigenmodes (GAEs), and fast-ion loss on NSTX (Kramer et al. 2013 a , 2016). Earlier SPIRAL was also used to predict alpha losses in ITER (Kramer et al.…”

Section: Numerical Simulation Toolsmentioning

confidence: 99%

“…This paper evaluates ripple-induced fast-ion loss in the SPARC tokamak design (Creely et al 2020). We use two existing numerical codes, ASCOT (Varje et al 2019) and SPIRAL (Kramer et al 2013a), to compute the orbits of alpha particles in the rippled magnetic field from birth at 3.5 MeV until they either thermalize or hit the wall. Because the orbit simulations are rather time-consuming, they have been carried out not for the SPARC V2 design but for its immediate predecessor (V1E), which had slightly smaller ripple (0.15 % versus 0.3 % at the outer edge) but identical plasma conditions (toroidal field, plasma current, major radius, minor radius, elongation: B T , I p , R 0 , a, κ).…”

Section: Introductionmentioning

confidence: 99%

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Fast-ion physics in SPARC

et al. 2020

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Potential loss of energetic ions including alphas and radio-frequency tail ions due to classical orbit effects and magnetohydrodynamic instabilities (MHD) are central physics issues in the design and experimental physics programme of the SPARC tokamak. The expected loss of fusion alpha power due to ripple-induced transport is computed for the SPARC tokamak design by the ASCOT and SPIRAL orbit-simulation codes, to assess the expected surface heating of plasma-facing components. We find good agreement between the ASCOT and SPIRAL simulation results not only in integrated quantities (fraction of alpha power loss) but also in the spatial, temporal and pitch-angle dependence of the losses. If the toroidal field (TF) coils are well-aligned, the SPARC edge ripple is small (0.15–0.30 %), the computed ripple-induced alpha power loss is small ( ${\sim } 0.25\,\%$ ) and the corresponding peak surface power density is acceptable ( $244\ \textrm{kW}\ \textrm {m}^{-2}$ ). However, the ripple and ripple-induced losses increase strongly if the TF coils are assumed to suffer increasing magnitudes of misalignment. Surface heat loads may become problematic if the TF coil misalignment approaches the centimetre level. Ripple-induced losses of the energetic ion tail driven by ion cyclotron range of frequency (ICRF) heating are not expected to generate significant wall or limiter heating in the nominal SPARC plasma scenario. Because the expected classical fast-ion losses are small, SPARC will be able to observe and study fast-ion redistribution due to MHD including sawteeth and Alfvén eigenmodes (AEs). SPARC's parameter space for AE physics even at moderate $Q$ is shown to reasonably overlap that of the demonstration power plant ARC (Sorbom et al., Fusion Engng Des., vol. 100, 2015, p. 378), and thus measurements of AE mode amplitude, spectrum and associated fast-ion transport in SPARC would provide relevant guidance about AE behaviour expected in ARC.

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Section: Numerical Simulation Toolsmentioning

confidence: 99%

Section: Numerical Simulation Toolsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fast-ion physics in SPARC

et al. 2020

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“…ICRH is known to cause fast ion generation 41 , and modeling has revealed that fast ion orbits are elongated in the major radial direction 44 , which can intersect mid-plane limiters at sufficiently high energies. At Tore-Supra, a similar mid-plane surface heating associated with fast ions was observed 9 , though this phenomenon is distinct from hot spots on antenna limiters associated with rectified RF sheaths 45 .…”

Section: A Erosion and Localized Surface Heating During Ion Cyclotromentioning

confidence: 99%

Imaging of molybdenum erosion and thermography at visible wavelengths in Alcator C-Mod ICRH and LHCD discharges

James¹,

Brunner²,

LaBombard³

et al. 2013

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We describe results from imaging observations of atomic line and continuum emission in the 550.6nm region on Alcator C-Mod. Both the 550.6nm neutral molybdenum emission and the adjacent 549nm continuum emission are imaged separately to isolate line emission. A few complications of using imaging to infer erosion in this wavelength region are discussed including subtraction of continuum emission and determination of an appropriate S/XB coefficient. Diagnostics of surface erosion and thermography using these emissions are briefly reviewed, and used to study phenomenology during ohmic operation, ion cyclotron range of frequencies heating (ICRH), and lower hybrid current drive (LHCD). In addition to broadening of Mo I emission regions in the outer divertor and main limiter during ICRH compared to ohmic operation, mid-plane localized heating of the main limiter associated with fast ion impact is observed which exceeds the divertor heat flux. During LHCD operation, several localized regions of increased brightness associated with hot-spots are interpreted as heating due to localized density peaking, which re-iterates the importance of imaging continuum emission for subtraction. These sources of surface heating exacerbate plasma-material interactions at the device wall and may require additional mitigation if they cannot be avoided in future machines.

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“…SPIRAL is a full particle-orbit following code that was developed to model energetic ion behaviour in tokamaks [16,17]. Figure 4 shows the results of SPIRAL used to simulate the losses due to EGAMs.…”

Section: Modelling and Inferred Egam Loss Mechanismmentioning

confidence: 99%

Beam ion losses due to energetic particle geodesic acoustic modes

Fisher¹,

Pace²,

Kramer³

et al. 2012

Nucl. Fusion

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We report the first experimental observations of fast-ion loss in a tokamak due to energetic particle driven geodesic acoustic modes (EGAMs). A fast-ion loss detector installed on the DIII-D tokamak observes bursts of beam ion losses coherent with the EGAM frequency. The EGAM activity results in a significant loss of beam ions, comparable to the first orbit losses. The pitch angles and energies of the measured fast-ion losses agree with predictions from a full orbit simulation code SPIRAL, which includes scattering and slowing-down.

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A Description of the Full Particle Orbit Following SPIRAL Code for Simulating Fast-ion Experiments in Tokamaks

Cited by 4 publications

References 7 publications

Fast-ion physics in SPARC

Fast-ion physics in SPARC

Imaging of molybdenum erosion and thermography at visible wavelengths in Alcator C-Mod ICRH and LHCD discharges

Beam ion losses due to energetic particle geodesic acoustic modes

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