Kinetic modelling of runaway electrons in dynamic scenarios

Abstract

Improved understanding of runaway-electron formation and decay processes are of prime interest for the safe operation of large tokamaks, and the dynamics of the runaway electrons during dynamical scenarios such as disruptions are of particular concern. In this paper, we present kinetic modelling of scenarios with time-dependent plasma parameters; in particular, we investigate hot-tail runaway generation during a rapid drop in plasma temperature. With the goal of studying runaway-electron generation with a self-consistent electric-field evolution, we also discuss the implementation of a collision operator that conserves momentum and energy and demonstrate its properties. An operator for avalanche runaway-electron generation, which takes the energy dependence of the scattering cross section and the runaway distribution into account, is investigated. We show that the simplified avalanche model of Rosenbluth & Putvinskii [Nucl. Fusion 1997 37 1355] can give inaccurate results for the avalanche growth rate (either lower or higher) for many parameters, especially when the average runaway energy is modest, such as during the initial phase of the avalanche multiplication. The developments presented pave the way for improved modelling of runaway-electron dynamics during disruptions or other dynamic events.

17 pages, 7 figures

References in corpus (4)

• Effective Critical Electric Field for Runaway-Electron Generation
• Kinetic modelling of runaway electrons in dynamic scenarios
• New velocity-space discretization for continuum kinetic calculations and Fokker-Planck collisions
• Radiation reaction induced non-monotonic features in runaway electron distributions

Cited by in corpus (25)

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• Generalized collision operator for fast electrons interacting with partially ionized impurities
• Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption
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• Multi-particle collision simulations of 2D one-component plasmas: anomalous transport and dimensional crossovers
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• NORSE: A solver for the relativistic non-linear Fokker-Planck equation for electrons in a homogeneous plasma
• Measurements of runaway electron synchrotron spectra at high magnetic fields in Alcator C-Mod
• A Physics-Informed Deep Learning Model of the Hot Tail Runaway Electron Seed
• Runaway dynamics in disruptions with current relaxation
• Kinetic modelling of runaway electron generation in argon-induced disruptions in ASDEX Upgrade
• Electron runaway in ASDEX Upgrade experiments of varying core temperature
• Dynamics of positrons during relativistic electron runaway
• Modelling of runaway electron dynamics during argon-induced disruptions in ASDEX Upgrade and JET
• Experimental and synthetic measurements of polarized synchrotron emission from runaway electrons in Alcator C-Mod
• Runaway-electron formation and electron slide-away in an ITER post-disruption scenario
• Validity of models for Dreicer generation of runaway electrons in dynamic scenarios
• Self-consistent modeling of runaway electron generation in massive gas injection scenarios in ASDEX Upgrade