2026/06/22 by Masaki Uchida, H. Tanaka, Hisayoshi Etou +4 · 1 voice
Physics and Astronomy · #Magnetic confinement fusion research #Ionosphere and magnetosphere dynamics #Gyrotron and Vacuum Electronics Research
paper · doi:10.1088/1741-4326/ae8038
openalex publication_date 2026/06/22 · openalex created_date 2026/06/23 · openalex updated_date 2026/07/20
Abstract The start-up and formation of overdense spherical tokamak plasmas by electron Bernstein waves with the microwave injection from a bottom port to suppress trapped electrons have been investigated in the Low Aspect ratio Torus Experiment (LATE). Experimental results show that the development of trapped electrons outside the last closed flux surface (LCFS) is effectively suppressed compared to cases using midplane outboard injection, suggesting improved coupling to current carrying passing electrons and the bulk electrons. Soft x-ray profiles suggest that the electron temperature is higher at the plasma core with the bottom injection than with the midplane outboard injection. These results indicate that the bottom injection is advantageous for core plasma heating, as it avoids the second-harmonic EC resonance heating as well as the Doppler-shifted fundamental EC heating of trapped electrons outside the LCFS.