ITER First Plasma (FP) operation aims to produce a plasma with current higher than 100 kA for a duration longer than 100 ms. However, the low values of plasma density and temperature associated with the initiation phase make it difficult to diagnose the plasma accurately. It is therefore essential to develop models for the available diagnostics for ITER FP operation in order to determine the necessary measurement ranges for plasma initiation and use them as inputs for controller development and assessment within the plasma control system (PCS). The use of accurate diagnostic models also helps to optimally prepare for, and analyse, ITER FP operation. A model developed for the H_α main chamber visible spectroscopy for FP shows that it is possible to measure H_α emission soon after breakdown for plasma temperatures higher than 3 eV and average plasma densities higher than 10¹⁷ m⁻³. The diagnostic model for the interferometer shows that for the proposed ITER FP scenarios, accurate measurements are possible for average plasma densities higher than 5 10¹⁷ m⁻³. The results from modelling of the hard x-ray monitor demonstrate that it can provide signals useful for runaway electron detection and can measure current levels typically down to 3 kA. Thus, these measurements can thus be used effectively by the PCS for runaway electron (RE) detection during FP operation. Improved diagnosis of the plasma state deducing, for example, parameters such as the plasma size and position, is possible by combining the measurements from the different FP diagnostics (density interferometer polarimeter and H_α main chamber visible spectroscopy), which will be available for ITER FP operation.

ITER First Plasma (FP) 操作旨在产生电流高于 100 kA、持续时间超过 100 ms 的等离子体。然而，与起始阶段相关的等离子体密度和温度的低值使得难以准确诊断等离子体。因此，必须为 ITER FP 操作的可用诊断开发模型，以确定等离子体启动所需的测量范围，并将其用作等离子体控制系统 (PCS) 内控制器开发和评估的输入。使用准确的诊断模型还有助于为 ITER FP 运行做好最佳准备和分析。为 FP的 H _α主室可见光谱开发的模型表明可以测量 H _α对于高于 3 eV 的等离子体温度和高于 10 ¹⁷ m ^{-3 的}平均等离子体密度，击穿后不久的发射。干涉仪的诊断模型表明，对于提议的 ITER FP 场景，平均等离子体密度高于 5 10 ¹⁷ m ^{-3 的}准确测量是可能的. 硬 X 射线监视器的建模结果表明，它可以提供对失控电子检测有用的信号，并且可以测量通常低至 3 kA 的电流水平。因此，PCS 可以有效地将这些测量用于 FP 操作期间的失控电子 (RE) 检测。通过结合不同 FP 诊断（密度干涉仪旋光仪和 H _α主室可见光谱仪）的测量结果，可以改进等离子体状态的诊断，例如推断等离子体尺寸和位置等参数，这可用于 ITER FP 操作。