Knock-on Tail Formation Due to Nuclear Elastic Scattering and Its Observation Method Using &lt;i&gt;γ&lt;/i&gt;-Ray-Generating &lt;sup&gt;6&lt;/sup&gt;Li+d Reaction in Tokamak Deuterium Plasmas

Matsuura, Hideaki; Sugiyama, Satomi; Kajimoto, Shogo; Sawada, Daisuke; Nishimura, Yuichi; Kawamoto, Yasuko

doi:10.1585/pfr.11.1403105

Cited by 7 publications

(10 citation statements)

References 22 publications

(61 reference statements)

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“…For detailed evaluation, more sophisticated simulations considering the anisotropy of the plasma would be necessary. Currently the analysis using the particle simulation code considering the NES phenomena is developing 20 . The discussion including anisotropic effects will be made in the subsequent analysis.…”

Section: Discussionmentioning

confidence: 99%

Indirect energy transfer channel between fast ions via nuclear elastic scattering observed on the large helical device

et al. 2022

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An energy transfer phenomenon between energetic ions, which cannot be explained only considering the Coulomb scattering process, was observed on a large helical device (LHD). This phenomenon often occurs in fusion reactivity enhancement and fast-ion slowing-down process that can be observed as a delay in the decay time of the D(d,n)3He neutron generation rate. The transferred energy required to induce such a reactivity enhancement or delay in the fast-ion slowing-down time (neutron decay time) was examined based on the Boltzmann−Fokker−Planck analysis in which a discrete energy transfer process, called nuclear elastic scattering (NES), is included. It was shown that even though the cross section of the NES is smaller than that of the Coulomb scattering, enough knock-on population appears in the energetic region in ion distribution function to induce the observable NES effects; thus, enough energy is transferred from beam ions to fast component of bulk ion distribution function indirectly and the transferred energy per unit time via NES is comparable to the Coulomb scattering rate. This study analytically demonstrates that the observed phenomena on LHD can be explained smoothly by considering the alternative indirect energy transfer channel between energetic ions, which can be comparable with the one via Coulomb scattering.

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Section: Discussionmentioning

confidence: 99%

Indirect energy transfer channel between fast ions via nuclear elastic scattering observed on the large helical device

et al. 2022

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“…According to the treatment developed by our research group, [34][35][36][37][38][39][40] the new velocity of the scattered ion is calculated using Equation ( 1) and is shown in Figure 3.…”

Section: Treatment Of Elastic Scattering In the Orbital Calculationmentioning

confidence: 99%

Effect of elastic scattering between ions and neutral particles on ion transport perpendicular to magnetic fields in divertor plasmas

Umezaki,

Matsuura,

Hoshino

2023

Contributions to Plasma Physics

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In divertor plasmas, atomic processes play a significant role in reducing the divertor heat load. In particular, the elastic scattering between ions and neutral particles can be characterized as a large‐angle scattering; this is in contrast with Coulomb scattering, which is dominated by small‐angle scattering. In a large‐angle scattering, a large fraction of the ion energy is transferred to the neutral particle, and the particle flight direction can be changed significantly. This process can generate additional particle transport perpendicular to magnetic field lines and affect plasma density profile in neutral‐rich divertor regions. However, in most edge plasma simulation codes, the elastic scattering with neutral particles is not taken into account in the direction perpendicular to the magnetic field lines. In this study, we performed a 2D orbital calculation without other drifts such as diamagnetic and E × B drifts to assess the effect of the elastic scattering on the density profile. The peak density is found to be decreased by 11.1 (6.3)% compared with the model that ignores the transport due to the elastic scattering, even at 3.0 (5.0) T magnetic field similar to that of the JT‐60SA (JA DEMO reactor) class. In addition, the ion transport can be expressed as a diffusion model by integrating the differential cross section over the large‐angle scattering range . The proposed method may be easily introduced into any integrated codes to consider the elastic scattering.

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“…Figure 4 shows the change of the ion and neutral particle velocities before and after the elastic scattering. The scattered ion velocity is expressed by the probability distribution function [13,14]. P represents the probability that an ion velocity changes from − → v ı to − → v ı as a result of a collision with a neutral particle that has velocity − → v n in the laboratory system.…”

Section: Large-angle Elastic Scattering Transport Model: the El Modelmentioning

confidence: 99%

“…In this work, the probability distribution function [13,14] (described in section 2.4) was applied to fluid equations forthe plasma, and the transport driven by largeangle elastic scattering between ions and neutral particles was studied including the radial direction. Furthermore, Fig.…”

Section: Introductionmentioning

confidence: 99%

Effect of Large-Angle Scattering between Ions and Neutral Particles on the Density Profile at the Divertor Plate

Umezaki

Matsuura

2021

Plasma and Fusion Research

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The better radial transport modelling of the SOL/divertor plasmas is required to obtain quantitative agreements between experimental values and simulation results towards the proper SOL/divertor plasma prediction of the future magnetic fusion devices. Various SOL/divertor codes (e.g. SONIC, SOLPS-ITER, EDGE2D, UEDGE, EMC3-Eirene, etc.) have been developed and applied to the interpretative simulations of the present fusion devices. Above codes treats the radial transport as a diffusion model and there exists uncertainty to decide the value of the diffusion coefficients. The simulation by the SONIC has resulted in a few times larger ion flux towards the divertor plate than the experimental value observed in JT-60U possibly due to such an uncertainty of the diffusion process. To achieve the quantitative agreement between the experiments and the simulation results is indispensable to predict SOL/divertor plasma parameters of the future fusion devices. Here, radial transport was simulated by considering large-angle elastic scattering between ions and neutral particles and by applying the probability distribution function to fluid equations in the divertor plasma. It was found that the density peak and ion flux are reduced by about half.

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Knock-on Tail Formation Due to Nuclear Elastic Scattering and Its Observation Method Using <i>γ</i>-Ray-Generating <sup>6</sup>Li+d Reaction in Tokamak Deuterium Plasmas

Cited by 7 publications

References 22 publications

Indirect energy transfer channel between fast ions via nuclear elastic scattering observed on the large helical device

Indirect energy transfer channel between fast ions via nuclear elastic scattering observed on the large helical device

Effect of elastic scattering between ions and neutral particles on ion transport perpendicular to magnetic fields in divertor plasmas

Effect of Large-Angle Scattering between Ions and Neutral Particles on the Density Profile at the Divertor Plate

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