Simulation and Overheating Alert Research for Beam Spot Temperatures on High-Field Side Protective Tiles in EAST-NBI

Abstract

Neutral Beam Injection (NBI), an auxiliary heating method in EAST, is evolving towards higher energy and longer pulses, leading to increased energy bombardment on the high-field side graphite protection tiles. This study explores the intricacies of theoretical injection energy and shine-through losses with respect to plasma density, NBI beam energy, and NBI pulse width. By evaluating the beam power distribution reaching the protective tiles, and subsequently assessing the temperature distribution on the tiles under varying pulse widths, a reliable comparison can be made between the simulated temperature results and experimental temperature data. To ensure the reliability of simulation results, the beam power distribution utilizes a two-dimensional Gaussian model and a particle model for contrast simulation. Similarly, the thermal deposition model employs a simplified uniform heating model, a analytic model and a finite element simulation model. As a reference, the experimentally measured data includes both infrared surface temperature measurements and buried thermocouple measurements. The objective of this study is to establish a correlation between key input variables and the protective tile temperature. By setting precise parameters, this research seeks to provide a predictive mechanism for thermal deposition, contributing to proactive overheating prevention and efficient adjustments to injection parameters and first-wall backend cooling metrics.