5:15 PM - 5:30 PM
[PEM31-07] Group motion of heteromorphic fine particles in HF discharge plasma
Keywords:fine particle plasma, heteromorphic particles, self organization, planetary motion, spin, dust plasma
Related with complex systems, fine-particle plasmas have much attention to scientists and engineers [1, 2]. Hence, we are trying to make fine-particle plasmas with heteromorphic particle distributions by using a high-frequency (HF) Ar plasma. And the motions of charged particles are observed. In a stainless steel chamber (150 mm in diam, 150 mmh), 100 mm in diam disk electrodes and a 80 mm in diam metal ring are set. In this experiment, HF argon discharge is produced at 10~13 Pa by applying HF voltage of about 270~290 Vrms to the lower disk-electrode with respect to the upper grounded disk-electrode. And a ring is added on the lower electrode to confine fine-particles. The particles used are silicon carbide, which has diameter of about 8 um, or silicon-nitride (about 8 um), or short hemp (about 25 um diam. 10 ? 1500 um long). They are injected from a dust dropper. A digital microscope camera (SELMIC LWD100) and a CCD video camera are used to investigate the particle behaviors. Under a condition of discharge voltage Vd= 280 Vrms, discharge current Id= 0.2 Arms and pressure p(Ar)= 13 Pa, a disk-shaped cloud is generated as shown in Fig. 1. Each particle motion and the particle-group motion are recorded by the cameras. We could observe planet-like motions like Fig. 2 (track of a SiC particle). In case of the short hemp, there are spin motions and planet-like motions. We conjecture that these motions are activated by the dust-acoustic perturbation.[1] Y. Hayashi, K. Tachibana, J. Vac. Sci. Technol. A 14 (2) (1996) 506.[2] H. Thomas, G.E. Morfill, V. Demmel, Phys. Rev. Lett. 73 (1994) 652.