Plasma parameters in the vicinity of the quartz window of a low pressure surface wave discharge produced in O2

Nonlocal effect of plasma resonances on the electron energy-distribution function in microwave plasma columns

“…The existence and precise role of plasma resonances nonetheless continues to be a subject of debate, due to a lack of convincing and comprehensive experimental validation [14]. Indirect evidence by Langmuir probe measurements have been reported, such as the presence of local peaks in the plasma-floating potential near the end of a plasma column [15], and the detection of high-energy electrons near the fused-silica windows in both tubular and planar-type surface-wave discharges [16,17,18,19]. It is well-known, however, that probe measurements are problematic in wave-sustained plasmas since metallic electrodes perturbs the self-consistent wave-plasma behavior.…”

Electron energy distribution functions in low-pressure oxygen plasma columns sustained by propagating surface waves

“…27͒ is well below the surface-wave frequency ͑2.45 GHz͒, indicating that acceleration of electrons in a resonant layer is likely to occur. The presence of highenergy tails was also observed near the dielectric window in planar surface-wave plasmas in argon 8,9 and oxygen 7,10 but was found to vanish rapidly when moving away from the wave launcher. In the cylindrical geometry, however, the plasma is continuously exposed to the strongly inhomogeneous radial electric field, which explains why the highenergy tail was observed over the whole plasma length.…”

Multi-Hollow Plasma Production along Dielectric Plate in Microwave Discharge

“…1(a). Details of the experimental apparatus and measurement techniques have been reported elsewhere, 5,6) and briefly a slot antenna (165 mm length, 10 mm width) and a flat or multi-hollow quartz plate (240 Â 240 Â 35 mm 3 ) were used in the present experiment. As illustrated in Fig.…”

“…First of all, microwave plasma was produced using a flat quartz plate where standing surface waves propagating along the quartz plate were observed together with density jump. 5,7) However, such density jump was suppressed by employing a multi-hollow plate. The dimensions of hollow are much smaller than the 915 MHz free-space wavelength ( 0 ¼ 327 mm): small diameter (d ¼ 5; 10; 15 mm), shallow depth (h ¼ 5; 10 mm), and short interval between adjacent hollows (l ¼ 20; 50 mm).…”