arXiv subjects

Svetlana Ratynskaia

Publications and source records attributed to Svetlana Ratynskaia.

5 recordsLinked to original sources

arXiv2026

FIREWALL: A surrogate model for the rapid assessment of tokamak wall loading and melting by runaway electrons

Runaway electron (RE) beams generated during tokamak disruptions can deposit highly localized heat loads on plasma-facing components, posing a serious risk of melting and damage. Monte Carlo particle transport simulations coupled with three-dimensional thermomechanical response modeling can quantify this damage but are too computationally demanding for device-scale assessments and extensive scenario scans. We present FIREWALL (Fast Integrated Runaway Electron WALL loads), a surrogate model that combines a database of \textsc{Geant4} volumetric energy-deposition profiles with a one-dimensional heat-diffusion solver for each wall element. FIREWALL retains the energy and incident angle distributions of impacting REs and predicts the spatiotemporal temperature evolution of detailed three-dimensional wall geometries up to the melting threshold. FIREWALL thus provides a fast physics-based framework for translating global RE simulations into global wall melting predictions, enabling large-scale screening of disruption scenarios while directing high-fidelity costly workflows to the limited wall regions where they are actually required.

physics.plasm-ph↗

arXiv2026

Wall damage due to oblique high velocity dust impacts

Runaway electron termination on plasma facing components can trigger material explosions that are accompanied by the expulsion of fast solid debris. Due to the large kinetic energies of the ejected dust particles, their subsequent mechanical impacts on the vessel lead to extensive cratering. Earlier experimental studies of high velocity micrometric tungsten dust collisions with tungsten plates focused exclusively on normal impacts. Here, oblique high velocity tungsten-on-tungsten mechanical impacts are reproduced in a controlled manner by a two-stage light gas gun shooting system. The strong dependence of the crater characteristics and crater morphology on the incident angle is documented. A reliable empirical damage law is extracted for the dependence of the crater depth on the incident angle.

physics.plasm-ph↗

arXiv2025

Modeling of runaway electron induced damage on boron-nitride tiles in WEST

The runaway electron (RE) - induced damage on boron nitride (BN) tiles mounted on the inner bumpers of the WEST tokamak is modeled employing available empirical input and experimental constraints, concerning the post-mortem documentation of the damaged material topology and infra-red camera observations of the long-time decay of the surface temperature. A newly developed work-flow for the modeling of brittle failure due to RE impacts, recently validated against a controlled DIII-D experiment, is employed. Monte Carlo simulations of RE transport into BN provide volumetric heat source maps for finite-element simulations of the linear thermoelastic material response, while the brittle failure onset is predicted on the basis of the Rankine criterion. The physics of thermal stress driven failure and explosion are well captured by this model, which exhibits high sensitivity to RE impact parameters. Despite the accidental nature of the damage events, the workflow predicts failure in accordance with observations for realistic loading specifications expected in WEST disruptions.

physics.plasm-ph↗

arXiv2023

Wall cratering upon high velocity normal dust impact

Dust-wall high speed impacts, triggered by the termination of runaway electrons on plasma facing components, constitute a source of erosion. Normal high velocity mechanical impacts of tungsten dust on bulk tungsten plates are reproduced in a controlled manner by light gas gun shooting systems. Post-mortem surface analysis revealed that three erosion regimes are realized; plastic deformation, bonding and partial disintegration. The large impact statistics allowed the extraction of reliable empirical damage laws in the latter regime, which can be employed for erosion estimates in future reactors.

physics.plasm-ph↗

arXiv2008

Scale-free vortex cascade emerging from random forcing in a strongly coupled system

The notions of self-organised criticality (SOC) and turbulence are traditionally considered to be applicable to disjoint classes of phenomena. Nevertheless, scale-free burst statistics is a feature shared by turbulent as well as self-organised critical dynamics. It has also been suggested that another shared feature is universal non-gaussian probability density functions (PDFs) of global fluctuations. Here, we elucidate the unifying aspects through analysis of data from a laboratory dusty plasma monolayer. We compare analysis of experimental data with simulations of a two-dimensional (2D) many-body system, of 2D fluid turbulence, and a 2D SOC model, all subject to random forcing at small scales. The scale-free vortex cascade is apparent from structure functions as well as spatio-temporal avalanche analysis, the latter giving similar results for the experimental and all model systems studied. The experiment exhibits global fluctuation statistics consistent with a non-gaussian universal PDF, but the model systems yield this result only in a restricted range of forcing conditions.

physics.plasm-ph↗