辐射诊断是一种重要的核聚变等离子体诊断手段。本文发展了一系列针对球形托卡马克优化的辐射诊断及其数据处理分析方法，满足了SUNIST装置和新建的SUNIST-2球形托卡马克装置的基础诊断需求，加深了我们对SUNIST与SUNIST-2两个球形托卡马克上内部磁重联事件（IRE）的理解。本文发展了模块化AXUV/SXR阵列式热辐射诊断，并开发了基于压缩感知的辐射剖面重建方法。针对AXUV探测器的特性应用了多种创新工程方案，将诊断模块缩小到尺寸与探测器接近，可以实现低场侧任意位置安装。实现了2 cm/3 cm的空间分辨率和500 kHz以上的频率响应。开发了基于压缩感知的辐射剖面重建方法，首次将压缩感知技术引入等离子体诊断的剖面重建中，实现了准确度显著高于Tikhonov正则化方法的重建结果，并具有一定的去噪能力。本文发展了多通道杂质滤波谱仪阵列和硬X射线诊断。开发了紧凑的集成光学耦合模块，实现了7谱线42通道滤波谱仪阵列的全系统单机柜集成；开发了4通道碲锌镉探测器硬X射线诊断系统；设计了在线式偏压集成控制系统，实现了探测器响应实时、连续、线性的在线调节，保证了不同类型通道之间响应一致，并为放电自动化控制对诊断响应实时高动态范围的调节创造了条件。本文发展了首套可见光波段被动式点测量离子多普勒光谱诊断系统。通过原子物理模型估算确认了测量被动C VI谱线估计主离子温度的可行性；通过对收光系统、色散系统和光电转换系统高信噪比设计，实现了离子温度空间分布的有效被动式单点测量，系统具有22 mm的空间分辨率和小于2 ms的时间分辨率，可以实现SUNIST-2等离子体放电几乎全过程离子温度径向分布测量。本文利用辐射诊断分析了球形托卡马克上的IRE，讨论了IRE的分类和产生机制。初步确认在先兆前期m/n=3/1的压强梯度驱动的模式线性增长，先兆后期通过非线性耦合激发了m/n=7/2的磁扰动模式，磁扰动能量增强并导致全局重联。依据等离子体参数统计分析结果表现出的差异，将两代装置上的IRE分为辐射猝灭型和辐射增强型。初步推断辐射猝灭型IRE受等离子体内压强梯度不稳定性驱动，而辐射增强型IRE与等离子体边界和真空室固体表面的相互作用相关，并对相应的实验现象做了初步解释。
Radiation diagnostic systems are crucial form of diagnostics on tokamaks. In this paper, we have developed optimized radiation diagnostic systems and corresponding data processing and analysis techniques for spherical tokamak devices, which meet the needs of SUNIST and the newly built spherical tokamak SUNIST-2, and deepen our understanding of the internal reconnection event (IRE) on both SUNIST and SUNIST-2.Modular AXUV/SXR arrays for thermal radiation measuring are developed on SUNIST and SUNIST-2, and a compressive sensing-based tomography method is developed. Various innovative engineering design solutions are applied to match the characteristics of the AXUV detectors, resulting in compact AXUV modules that can be mounted anywhere on the low-field side with size approaching to that of the detector. The systems achieve spatial resolution of 2 cm/3 cm and a frequency response above 500 kHz. Furthermore, we have introduced compressive sensing technology into tomography of plasma diagnostics for the first time, and developed a tomography method based on compressive sensing. The reconstructed results by the new method surpasses that achieved by Tikhonov regularization method, and the method also exhibited certain denoising capabilities.A multi-channel filterscope array and a hard X-ray diagnostic system are developed. We developed compact integrated optical coupling modules to facilitate accommodating the 7-wavelength 42-channel filterscope array into single cabinet. A 4-channel hard X-ray diagnostic system equipped with CdZnTe detectors is also been developed. An online integrated bias control system is designed to achieve real-time, continuous, and linear adjustment of the detector response, ensuring consistent response across different channels and facilitating real-time and high dynamic range adjustment of response through automatic discharge control.The first passive and point measurement ion Doppler spectroscopy diagnostic system in visible light band is developed. The feasibility of estimating main ion temperature by measuring the passive CVI spectrum is confirmed by calculations based on an atomic physics model. By designing the optical system, dispersive system, and photoelectric conversion system to achieve high signal-to-noise ratio signal, we successfully realized effective passive and point measurement of ion temperature with spatial resolution for the first time. With a spatial resolution of 22 mm and a temporal resolution of less than 2 ms, the system is capable for measuring the radial distribution of ion temperature throughout the entire SUNIST-2 plasma discharge.We analyzed IREs on spherical tokamaks using radiation diagnostic systems and discussed their classification and generation mechanism. We preliminarily confirm that m/n=3/1 mode driven by pressure gradient grows during precursor process, then m/n=7/2 mode magnetic disturbance is excited through nonlinear coupling, leading to enhanced magnetic disturbance energy triggering reconnection events. Statistical analysis based on differences in plasma parameters classifies IREs into radiation quenching type and radiation enhancing type. It is inferred that radiation quenching IREs are driven by pressure gradient instability while radiation enhancing IREs are associated with interaction between plasma boundary and vacuum chamber surface. Preliminary explanations of the corresponding experimental phenomena were given.
