Validation of the BEAMS3D neutral beam deposition model on Wendelstein 7-X

Lazerson, S.; Ford, O.; Nuehrenberg, C.; Äkäslompolo, S.; Pölöskei, P. Zs.; Machielsen, M.; McNeely, P.; Vanó, L.; Rust, N.; Bozhenkov, S.; Neelis, T. W. C.; Graves, J. P.; Pfefferlé, David; Spanier, A.; Hartmann, D.; Marushchenko, N. B.; Turkin, Y.; Hirsch, M.; Chaudhary, N.; Hoefel, U.; Stange, T.; Weir, G.; Pablant, N.; Langenberg, A.; Traverso, P.; Valson, P.; Knauer, J.; Brunner, K. J.; Pasch, E.; Beurskens, M.; Damm, H.; Fuchert, G.; Nelde, P.; Scott, E. R.; Hergenhahn, U.; Pavone, A.; Andreeva, T.; Schilling, J.; Brandt, C.; Neuner, U.; Thomsen, H.; Jakubowski, M.; Ali, Adnan; Gao, Yu; Niemann, H.; Sitjes, A. Puig; Koenig, R.; Wolf, R. C.

doi:10.1088/1741-4326/ab8e61

Cited by 19 publications

(22 citation statements)

References 27 publications

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“…Experiments began with injection into plasmas sustained by electron cyclotron resonance heating (ECRH), allowing for control of target plasmas and densities. These experiments provided a wealth of information to help validated both neutral beam deposition [3] and wall loss estimates [4]. Discharges heated solely by neutral beam injection (NBI) were also demonstrated.…”

Section: Introductionmentioning

confidence: 96%

First neutral beam experiments on Wendelstein 7-X

Team¹,

Lazerson²,

Ford³

et al. 2021

Nucl. Fusion

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In the previous divertor campaign, the Wendelstein 7-X (W7-X) device injected 3.6 MW of neutral beam heating power allowing for the achievement of densities approaching 2 × 10 20 m −3 , and providing the first initial assessment of fast ion confinement in a drift optimized stellarator. The neutral beam injection (NBI) system on W7-X is comprised of two beam boxes with space for four radio frequency sources each. The 3.6 MW of heating reported in this work was achieved with two sources in the NI21 beam box. The effect of combined electron-cyclotron resonance heating (ECRH) and NBI was explored through a series of discharges varying both NBI and ECRH power. Discharges without ECRH saw a linear increase in the line-integrated plasma density, and strong peaking of the core density, over the

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Section: Introductionmentioning

confidence: 96%

First neutral beam experiments on Wendelstein 7-X

Team¹,

Lazerson²,

Ford³

et al. 2021

Nucl. Fusion

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“…The fast, full collisional-radiative model relies on a Gaussian beam shape description and models the halo perpendicular to the beam axis using ionization and charge-exchange fall-off lengths. At W7-X, a validated Monte-Carlo code (BEAMS3D) [11] is used, among other purposes, to calculate the beam deposition.…”

Section: Jinst 18 P10029mentioning

confidence: 99%

Fast forward modeling of neutral beam injection and halo formation including full Balmer-α emission prediction at W7-X

Bannmann,

Ford,

Hoefel

et al. 2023

J. Inst.

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A full collisional-radiative (CR) neutral beam injection model based on Gaussian pencil (Gausscil) beams and a diffusive CR neutral halo model are presented. The halo is a neutral cloud around the neutral beam forming due to multiple charge exchange (CX) reactions. Both models do not rely on Monte-Carlo techniques and are thereby orders of magnitude faster than commonly used models. To model the neutral halo a system of coupled diffusion equations is solved numerically, enforcing mixed boundary conditions. From the equilibrium hydrogen neutral densities in the second excited energy state (n = 3), the Balmer-α emission intensity is calculated and the full spectrum is predicted, including effects as Doppler shifts and broadening due to the complex neutral beam geometry and the motional Stark effect (MSE) from the magnetic field. All forward models are implemented in the Minerva [1] Bayesian analysis framework to enable detailed multivariant inference from Balmer-α spectroscopy data. The modeled neutral beam and halo densities are successfully verified against calculations with a validated Monte-Carlo code for the W7-X beam and plasma geometry, especially proving the validity of the halo diffusion ansatz. A comparison of the predicted emission spectra with the experimental data proves the accuracy of the implemented model. All important parameters defining the neutral beams are inferred and compared to available reference values.

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“…BEAMS3D's deposition model has been validated [30] and a preliminary validation and benchmarking of the slowing down model has been done [29]. The simulations for this work were done using a new feature created for BEAMS3D that models fusion births and uses the birth rates to initialize particles for simulation [19].…”

Section: Energetic Particle Simulationsmentioning

confidence: 99%

Energetic particle optimization of quasi-axisymmetric stellarator equilibria

et al. 2022

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An important goal of stellarator optimization is to achieve good confinement of energetic particles such as, in the case of a reactor, alphas created by Deuterium-Tritium (D-T) fusion. In this work, a fixed-boundary stellarator equilibrium was re-optimized for energetic particle confinement via a two-step process: first, by minimizing deviations from quasiaxisymmetry (QA) on a single flux surface near the mid-radius, and secondly by maintaining this improved quasi-axisymmetry while minimizing the analytical quantity ΓC , which represents the angle between magnetic flux surfaces and contours of J ||, the second adiabatic invariant. This was performed multiple times, resulting in a group of equilibria with significantly reduced energetic particle losses, as evaluated by Monte Carlo simulations of alpha particles in scaled-up versions of the equilibria. This is the first time that energetic particle losses in a QA stellarator have successfully been reduced by optimizing ΓC. The relationship between energetic particle losses and metrics such as QA error (E qa) and ΓC in this set of equilibria were examined via statistical methods and a nearly linear relationship between volume-averaged ΓC and prompt particle losses was found.

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Validation of the BEAMS3D neutral beam deposition model on Wendelstein 7-X

Cited by 19 publications

References 27 publications

First neutral beam experiments on Wendelstein 7-X

First neutral beam experiments on Wendelstein 7-X

Fast forward modeling of neutral beam injection and halo formation including full Balmer-α emission prediction at W7-X

Energetic particle optimization of quasi-axisymmetric stellarator equilibria

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