Occurrence of ionization instability associated with plasma bubble in glow discharge magnetized plasma

Floating potential fluctuations of glow discharge magnetized plasma are found to expose mixed mode oscillations (MMOs) in the existence of plasma bubble. Plasma bubble has been formed by emerging density gradient in the form of a sheath around a cylindrical and spherical grid to a critical value of applied potential. Two Langmuir probes, LP₁ and LP₂, are retained in the ambient plasma to collect the plasma floating potential fluctuations at two different locations of the plasma system. The perceived instability pattern shows regular-irregular-regular MMOs under various imposed conditions. Furthermore, various nonlinear techniques such as phase space plot, recurrence plot and Hurst exponent have been executed to understand the underlying dynamical behavior of the system. Low-frequency (∼200–1200 Hz) oscillations are also supposed and are inferred as ion-acoustic waves excited by ionization instability. The observed results are then validated with the theory of the instability based on a fluid hydrodynamic approach. (paper)