Long plasma generation using microwave slot antennas on a rectangular waveguide

Abstract

30-cm-class long plasmas were generated using 2.45-GHz microwave slot antennas on a rectangular waveguide with a T-shaped ridge for the development of high performance ion sources or for plasma reactors for large-area material processing. The microwave coupling efficiencies above 85% were achieved for Ar, N2, and O2 over large flow rate ranges. From the electric fields on the inner wall E side of the waveguide, standing waves with the maximum electric field strength of about 30 kV/m were expected to be excited in the waveguide, depending on the location of the T-shaped ridge. The plasma density for Ar was in the order of 1017 m−3 and for N2 and O2 1016 m−3 in a discharge chamber in front of the slot antennas. The electron temperature for Ar ranged from 3 to 4 eV and for N2 and O2 from 3 to 8 eV. The spatial profiles of the ion saturation current for Ar were almost flat in the discharge chamber although the profiles for N2 and O2, with large flow rates or near the antennas, were slightly rough.

Scaling of microwave slot antenna (SLAN): a concept for efficient plasma generation

“…An example for linear design has been demonstrated by Tahara et al [33]-power is distributed by use of slot antennas from a rectangular waveguide with a T-shaped ridge along the waveguide (30 cm).…”

Transient Electric Field Shaping With the Linear Combination of Configuration Field Method for Enhanced Spatial Control of Microwave Plasmas

“…Here, the plasma is produced by a propagating surface-wave along the plasma in the glass tube, while the surface-wave propagation is sustained by the plasma itself. Large-area microwave plasmas can also be generated by radiating microwave power with a slot antenna array [9], [10]. The microwave-to-plasma applicator, called the slot antenna array, can have a linear, rectangular, circular, or annular geometry depending on the plasma vessel.…”