Experimental Study of Blob Dynamics and Turbulence Spreading in the Sol of IR-T1 Tokamak by Mix-probe

The scrape-off layer (SOL) of tokamak plasmas is characterized by complex transport phenomena, significantly influenced by transient plasma structures known as blobs. To investigate these dynamics in the IR-T1 tokamak, a novel electrostatic diagnostic, the Mix-probe, integrating both Langmuir probe (LP) and Ball-Pen probe (BPP) functionalities, was deployed. This advanced probe enabled simultaneous local measurements of electron density fluctuations ( $$\widetilde {{{n}_{e}}}$$ ), plasma potential fluctuations ( $$\widetilde {{{{{\varphi }}}_{p}}}$$ ), and electron temperature fluctuations ( $$\widetilde {{{T}_{e}}}$$ ). Conditional averaging of the ion saturation current (Isat) revealed the presence of blob-like structures at the plasma edge. Utilizing these measurements and simplified theoretical models, we estimated the turbulent particle flux ( $${{{{\Gamma }}}_{r}}$$ ) and the turbulence spreading term (S), providing initial insights into the role of blobs in particle transport and turbulence propagation in the IR-T1 SOL. The successful implementation of the Mix-probe demonstrates its potential for detailed investigations of plasma edge turbulence, contributing to a better understanding of transport mechanisms crucial for fusion energy development.