Kyeong K. Chi* and Rod W. Boswell

Plasma Research Laboratory, Research School of Physical Sciences and Engineering
ANU, Canberra, ACT0200, Australia
kkchi@samsung.co.kr

The helicon wave-heated plasma can produce a very high density plasma under a low pressure with a weak magnetic field configuration. The plasma has three categories of plasma heating modes: capacitive (E-), inductive (H-), and helicon wave heated (W-) modes, depending on the external parameters such as pressure, magnetic field, and rf power and so on, and there has been many works for the understanding of these modes.

In this work, we studied the mode transitions of in a helicon plasma through the electrical measurements. The plasma impedances were determined by measurements of the amplitudes and phase shift of the current and voltage on the antenna which was considered as a primary coil. It is shown that the plasma impedances determined by the electrical measurements were well-defined and undergo a corresponding transition as the mode change of E-H-W. The transitions of the equivalent resistance and reactance were investigated as a function of rf power, pressure, and magnetic field. The results were compared with the internal plasma parameters, the spatial distribution of the plasma density and the waves in the plasma using a Langmuir probe and a B-dot probe and also explained by theories of collisional and collisionless electron heating mechanisms.