Plasma diagnostics is the field of study that focuses on developing and using techniques to diagnose and characterize plasmas. Plasmas are ionized gases that are commonly found in various natural and industrial settings, such as in stars, lightning, and plasma processing tools. Plasma diagnostics typically involves the use of various instruments and techniques, such as spectroscopy, interferometry, and Langmuir probes, to measure parameters such as temperature, density, composition, and electric fields within a plasma. These measurements are crucial for understanding the properties and behavior of plasmas, which in turn is essential for improving various plasma-based technologies and processes. Overall, plasma diagnostics plays a key role in advancing our understanding of plasmas and optimizing their use in a wide range of applications, from fusion energy research to semiconductor manufacturing.