A study of M=0 and M=1 helicon wave generation in a weakly magnetized inductively coupled plasma

Summary form only given, as follows.Recently, it has been observed the helicon wave generation in a weakly magnetized inductively coupled plasmas (ICP) with the floating and conducting boundaries. In this experiment, the characteristics of helicon waves coupled with the current directions of the external ICP antenna were studied. Measurements were carried out in a weakly magnetized ICP. Plasma was confined in a cylindrical S/S chamber (500 mm dia/spl Omega/600 mm length) so it was the conducting boundary condition. Ar plasma density was approximately 3/spl Omega/10/spl circ/10cm/spl circ/-3/spl sim/5/spl Omega/10/spl circ/11cm/spl circ/-3 with the input power 300 W/spl sim/1000 W, respectively. Using the Helmholtz external coils, uniform DC magnetic field was produced up to 80 Gauss. A floated B-dot probe, compensated to the capacitively coupled components in the signal, was employed to measure the wave field in the plasma. Antenna configures as two turn loops composed of an inner one with 120 mm in diameter and an outer one with 350 mm in diameter, respectively. In case of the same direction of the current flow to the inner and outer loops, it was found that m=0 mode helicon wave was launched and in contrast, when the opposite currents flow to the antenna, m=1 mode wave was generated. Observation shows that the wave number of m=1 helicon wave was proportional to the ratio of the plasma density to the strength of external magnetic field but the wave number for m=0 mode has no strong relation to the ratio. These results will be presented.