Ambipolar and non-ambipolar diffusion in an rf plasma source containing a magnetic filter

作者：Lafleur T^*; Aanesland A

来源：Physics of Plasmas, 2014, 21(6): 063510.

DOI：10.1063/1.4885109

By placing a magnetic filter across a rectangular plasma source (closed at one end with a ceramic plate and an rf antenna, and terminated at the opposite end by a grounded grid), we experimentally investigate the effect of conducting and insulating source walls on the nature of the plasma diffusion phenomena. The use of a magnetic filter creates a unique plasma, characterized by a high upstream electron temperature (T-eu similar to 5 eV) near the rf antenna and a low downstream electron temperature (dT(ed) similar to 1 eV) near the grid, which more clearly demonstrates the role of the source wall materials. For conducting walls a net ion current to ground is measured on the grid, and the plasma potential is determined by a mean electron temperature within the source. For insulating walls the plasma potential is determined by the downstream electron temperature (i.e., V-p similar to 5.2T(ed) in argon), and the net current to the grid is exactly zero. Furthermore, by inserting a small additional upstream conductor (that can be made floating or grounded through an external circuit switch), we demonstrate that the plasma potential can be controlled and set to a low (V-p similar to 5.2T(ed)), or high (V-p similar to 5.2T(eu)) value.

• 出版日期2014-6