Chao Shi

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 and a thermal conduction 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.

Neutral Beam Injection (NBI) is one of the four efficient ways of assistant heating on the Experimental Advanced Superconducting Tokamak (EAST) device. Measures have been taken to ensure more reliable monitoring of NBI components’ thermal data. Infrared thermometers, unlike surface-mounted thermocouples, have the advantage of non-contact and thus will not cause interference and get far less chance of malfunctioning [Childs et al., Rev Sci. Instruments 71, 2959–2978 (2000)]. In this paper, the remote infrared temperature measurement with optical fiber is reported to meet the requirement of the EAST-NBI diagnostic system. Some tests have been conducted on the remote infrared temperature measurement under the working condition, and an atmospheric propagation simulation was performed to estimate the atmosphere absorption. The results indicate that the detector’s response is in line with the theory, and the atmosphere absorption within a certain wavelength should not be ignored. Temperature measurement error is within one percent at temperatures above 200 °C. So, for the temperature range of 200–600 °C, the remote infrared temperature measurement by the optical fiber can fully meet its expectation.