Density transition characteristics in magnetized plasma by voltage biasing

Summary form only given, as follows. Self-excited transitions between two states were investigated by the voltage biasing to an inserted electrode in the inner region of a RP produced, magnetized plasma. Argon plasma was produced by a four-turn spiral antenna at a pressure of P/sub 0/ = 0.1 /spl sim/ 10 mTorr. The continuous output rf power and frequency of P/sub rf/ = 160 /spl sim/ 500 W and f/sub rf/ = 7 MHz, respectively, were applied to a linear device, 45 cm in diameter and 170 cm in axial length, with the uniform magnetic field of B = 500 G. In order to control the radial potential profile, we used ten concentric, segmented rings, made of stainless steel with a thickness of 0.03 cm, as biased electrodes. Repeated transition phenomena with abrupt reductions and jumps of the electron density were observed (flip-flop pattern in bistable systems), by voltage biasing to an inserted electrode in the inner region of a cylindrical magnetized plasma. These global, self-excited, density transitions and back ones between two states were accompanied by changes of the floating potential profile and the bias current tinder various parameters. Detailed spatio-temporal plasma characteristics were also investigated using a 24 channel Langmuir probe array. Control of the staying time probability in one of two states with hysteresis loops was attempted, changing the bias voltage, which showed the importance of a sheath region as well as fine structural patterns.