[21a-136-1~12] 8.5 Plasma phenomena, emerging area of plasmas and their new applications

[21a-136-9] Measurement of Argon Arc Thermal Plasma Injected into Water

Yuya Matsuoka¹, Jun Kawamura¹, Ryujiro Suzuki¹, Atsushi Nezu^2,4, Shinsuke Mori³, 〇Hiroshi Akatsuka^1,4 (1.Tokyo Tech. SE, 2.Tokyo Tech. TSD, 3.Tokyo Tech. SMCT, 4.Tokyo Tech. IIR)

Keywords:arc plasma ejected into water, spectroscopic measurement of arc plasma, transport phenomena induced by arc jet in water

Arc discharge plasma process is expected as a basic technology for decommissioning of Fukushima Daiichi Nuclear Power Plant. Laser technology is considered to be difficult due to color center formation by γ-ray. Hence, arc-cutting technology is one of the promising methods. However, the water flow and the heat transfer from the arc plasma to water is not yet clarified. The main objective of the present study is to investigate the plasma in the water and transport phenomena of the water. It was found that T_e and N_e ranges about 0.6 - 2.2 eV and 10²¹ - 10²³ m^-3, respectively, both of which become lower as it flows to the downstream direction. We found that the water flow velocity ranges about 20 - 80 cm/s with PIV method, and that it increases as the discharge current increases. We also found a peak of Nu for T_e ~ 8000 K, which can be attributed to the dominant recombination of Ar⁺ ion on the interface.