Drift of ablated material after pellet injection in a tokamak

TL;DR

This paper introduces a fast semi-analytical model to predict the radial drift of ablated material after pellet injection in tokamaks, aiding disruption mitigation strategies in fusion reactors like ITER.

Contribution

A novel one-dimensional semi-analytical model that efficiently estimates ablated material drift considering Alfvén and ohmic currents in tokamaks.

Findings

Model accurately predicts radial displacement of ablated material.

Enables rapid calculations for disruption mitigation planning.

Applicable to ITER pellet injection scenarios.

Abstract

Pellet injection is used for fuelling and controlling discharges in tokamaks, and it is foreseen in ITER. During pellet injection, a movement of the ablated material towards the low-field side (or outward major radius direction) occurs because of the inhomogeneity of the magnetic field. Due to the complexity of the theoretical models, computer codes developed to simulate the cross-field drift are computationally expensive. Here, we present a one-dimensional semi-analytical model for the radial displacement of ablated material after pellet injection, taking into account both the Alfv\'en and ohmic currents which short-circuit the charge separation creating the drift. The model is suitable for rapid calculation of the radial drift displacement, and can be useful for e.g. modelling of disruption mitigation via pellet injection.