Visualization of ion dynamics during gas puffing in the RT-1 magnetospheric plasmas using a coherence imaging spectroscopy*

Particle transport in laboratory magnetospherere is studied by using the Ring trap 1 (RT-1) device. The RT-1 imitates a self-organized plasma in a planetary magnetosphere. The plasma achieved the stable confinement of high beta plasma in a dipole magnetic field. A steep peaked electron density profile and a spontaneous toroidal rotation of ions are observed under the self-organization phenomenon. Neutral Helium gas is puffed during 5 ms at t = 0.1 s into a plasma to perturb the electron density. Just after the gas puffing, the recovery of ion temperature and flow velocity is measured by using a coherence imaging spectroscopy to elucidate the ion dynamics in self-organized plasmas. The ion temperature in a poloidal plane with the gas puffing increases at t = 0.2 s, and the increased area forms a belt structure at the outer confinement region. The acceleration and deceleration of the flow velocity is also divided into the inner and the outer areas. Near the boundary area the electron density fluctuation at the frequency of 600 Hz is observed concomitant with a magnetic fluctuation. Based on these results, the self-organization mechanism will be discussed.