Optimizing the Plasma startup through ECR plasma pre-ionization in Taban Tokamak via Triple Langmuir probe

• Published in: Fusion engineering and design 2020-01, Vol.150, p.111362, Article 111362
• Main Authors: Mirzaei, H.R., Amrollahi, R., Ghasemi, M.
• Format: Article
• Language: English
• Subjects: Cyclotron resonance; Diagnostic systems; Electron cyclotron resonance; Electron energy; Gas pressure; Ionization; Langmuir waves; Optimization; Parameters; Plasma; Pre-ionization; Preionization; Startup; Tokamak; Tokamak devices; Triple Langmuir probe
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2019.111362

In the present study, a pre-ionization using a 2.45 GHz microwave through Electron Cyclotron Resonance (ECR) waves was investigated to assist the current startup in Taban tokamak. Since the characteristics of the ECR plasma depend on the gas pressure, the influence of changing the pressure of the filling gas on the ECR plasma parameters has been studied both theoretically and experimentally. Based on the obtained results, the optimum condition has been determined and the tokamak plasma parameters measured in optimal conditions are presented. A proper Triple Langmuir Probe (TLP) has been constructed and used in the experimental tests of this study. Using this diagnostic, the plasma parameters such as electron temperature, floating potential and density were measured. Steps to design and manufacture of the employed TLP are presented in detail. Due to the importance of gas pressure in low frequency ECR startup, it is crucial to determine the optimal startup conditions through controlling the filling gas pressure.