Time Evolution of Power Spectrum Density in Spontaneous Transition in Cylindrical Magnetized Plasma

Abstract

Preliminary observation results are reported for a new discharge regime in the Plasma Assembly for Nonlinear Turbulent Analysis (PANTA), where spontaneous transitions in the equilibrium profile and fluctuation spectra occur. Two different states are defined by using the mean density value. Axial and radial profiles are observed for the two states, and large profile changes are found. The spatiotemporal evolution of the transition front is measured. Changes in the fluctuation spectrum are evaluated using conditional average and lock-in average.

Impact of helium neutral gas puff on plasma turbulence in linear magnetized argon plasmas

“…16,17 Different types of mode competition events were reported in previous studies. In experiment, mutual interactions between streamers and solitary waves, 9 different types of streamers, 26 drift wave eddies and zonal flows, 37 and drift waves and D'Angelo modes 17 were found. In the numerical simulation, dynamic competitions among zonal flows, streamers, and flute modes utilizing the ion-neutral collision frequency as a control parameter were investigated in detail.…”

“…With this discharge condition, the streamer structure is nonlinearly excited by drift waves. [24][25][26][27] In addition, drift waves also excite a sheared axial flow structure which secondarily drives the D'Angelo mode in the inner radii. 16,17 The helium gas injector is illustrated in Fig.…”

“…PSD after the argon gas puff is qualitatively equivalent to that observed in a discharge with a higher neutral argon pressure at the plasma source region. 26…”